77 FR 37352 - Reporting and Notice Requirements for Deferred Vested Benefits Under Section 6057

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-21

... contains proposed regulations that would provide guidance relating to automatic extensions of time for... the Income Tax Regulations on automatic extensions. The proposed regulations would also provide... to the Internal Revenue Service, Attn: IRS Reports Clearance Officer, SE:CAR:MP:T:T:SP; Washington...

The picosecond laser for tattoo removal.

PubMed

Hsu, Vincent M; Aldahan, Adam S; Mlacker, Stephanie; Shah, Vidhi V; Nouri, Keyvan

2016-11-01

The prevalence of tattoos continues to grow as modern society's stigma towards this form of body art shifts towards greater acceptance. Approximately one third of Americans aged 18-25 and 40 % of Americans aged 26-40 are tattooed. As tattoos continue to rise in popularity, so has the demand for an effective method of tattoo removal such as lasers. The various colors of tattoo inks render them ideal targets for specific lasers using the principle of selective photothermolysis. Traditional laser modalities employed for tattoo removal operate on pulse durations in the nanosecond domain. However, this pulse duration range is still too long to effectively break ink into small enough particles. Picosecond (10 -12 ) lasers have emerged at the forefront of laser tattoo removal due to their shorter pulse lengths, leading to quicker heating of the target chromophores, and consequently, more effective tattoo clearance. Recent studies have cited more effective treatment outcomes using picosecond lasers. Future comparative studies between picosecond lasers of various settings are necessary to determine optimal laser parameters for tattoo clearance.

Algorithm for Automatic Detection, Localization and Characterization of Magnetic Dipole Targets Using the Laser Scalar Gradiometer

DTIC Science & Technology

2016-06-01

TECHNICAL REPORT Algorithm for Automatic Detection, Localization and Characterization of Magnetic Dipole Targets Using the Laser Scalar...Automatic Detection, Localization and Characterization of Magnetic Dipole Targets Using the Laser Scalar Gradiometer Leon Vaizer, Jesse Angle, Neil...of Magnetic Dipole Targets Using LSG i June 2016 TABLE OF CONTENTS INTRODUCTION

Turbo machine tip clearance and vibration measurements using a fibre optic laser Doppler position sensor

NASA Astrophysics Data System (ADS)

Pfister, T.; Büttner, L.; Czarske, J.; Krain, H.; Schodl, R.

2006-07-01

This paper presents a novel fibre optic laser Doppler position sensor for single blade tip clearance and vibration measurements at turbo machines, which offers high temporal resolution and high position resolution simultaneously. The sensor principle is based on the generation of a measurement volume consisting of two superposed fan-like interference fringe systems with contrary fringe spacing gradients using wavelength division multiplexing. A flexible and robust measurement system with an all-passive fibre coupled measurement head has been realized employing diffractive and refractive optics. Measurements of tip clearance and rotor vibrations at a transonic centrifugal compressor performed during operation at up to 50 000 rpm (833 Hz) corresponding to 21.7 kHz blade frequency and 586 m s-1 blade tip velocity are presented. The results are in excellent agreement with those of capacitive probes. The mean uncertainty of the position measurement was around 20 µm and, thus, considerably better than for conventional tip clearance probes. Consequently, this sensor is capable of fulfilling the requirements for future active clearance control systems and has great potential for in situ and online tip clearance and vibration measurements at metallic and non-metallic turbine blades with high precision.

Urea clearance: a new technique based on microdialysis to assess liver blood flow studied in a pig model of ischemia/reperfusion.

PubMed

Farnebo, S; Winbladh, A; Zettersten, E K; Sandström, P; Gullstrand, P; Samuelsson, A; Theodorson, E; Sjöberg, F

2010-01-01

Delayed detection of ischemia is one of the most feared postoperative complications. Early detection of impaired blood flow and close monitoring of the organ-specific metabolic status may therefore be critical for the surgical outcome. Urea clearance is a new technique for continuous monitoring of alterations in blood flow and metabolic markers with acceptable temporal characteristics. We compare this new microdialysis technique with the established microdialysis ethanol technique to assess hepatic blood flow. Six pigs were used in a liver ischemia/reperfusion injury model. Microdialysis catheters were placed in liver segment IV and all circulation was stopped for 80 min, followed by reperfusion for 220 min. Urea and ethanol clearance was calculated from the dialysate and correlated with metabolic changes. A laser Doppler probe was used as reference of restoration of blood flow. Both urea and ethanol clearance reproducibly depicted changes in liver blood flow in relation to metabolic changes and laser Doppler measurements. The two techniques highly correlated both overall and during the reperfusion phase (r = 0.8) and the changes were paralleled by altered perfusion as recorded by laser Doppler. Copyright © 2010 S. Karger AG, Basel.

Laboratory model for the study and treatment of traumatic tattoos with the Q-switched ruby laser

NASA Astrophysics Data System (ADS)

Silverman, Richard T.; Lach, Elliot

1994-09-01

The outcome of laser tattoo removal is dependent on the type of laser and characteristics of the tattoo. A rabbit model was developed to study the Q-switched ruby laser in the treatment of traumatic tattooing. On the backs of white New Zealand rabbits, three 3 cm patches were dermabraded and dressed with carbon black and antibiotic ointment. After a healing period of eight weeks, pre-treatment biopsies were obtained, and the rabbits were treated with the Q- switched ruby laser at various fluence settings with a pulse width of 34 nsec. At set intervals, further biopsies were obtained and studied with light and electron microscopic analysis, and photodocumentation was performed. Grossly, clearance of the tattooed areas was noted in the laser treated specimens. More effective clearance was observed with higher fluence treatment. No infections occurred, and hair regrowth was noted in all cases, though the rate seemed to be altered by laser treatment.

Multiple-Diode-Laser Gas-Detection Spectrometer

NASA Technical Reports Server (NTRS)

Webster, Christopher R.; Beer, Reinhard; Sander, Stanley P.

1988-01-01

Small concentrations of selected gases measured automatically. Proposed multiple-laser-diode spectrometer part of system for measuring automatically concentrations of selected gases at part-per-billion level. Array of laser/photodetector pairs measure infrared absorption spectrum of atmosphere along probing laser beams. Adaptable to terrestrial uses as monitoring pollution or control of industrial processes.

A continuously variable beam-diameter, high-fluence, Q-switched Nd:YAG laser for tattoo removal: comparison of the maximum beam diameter to a standard 4-mm-diameter treatment beam.

PubMed

Bernstein, Eric F; Civiok, Jennifer M

2013-12-01

Laser beam diameter affects the depth of laser penetration. Q-switched lasers tend to have smaller maximum spot sizes than other dermatologic lasers, making beam diameter a potentially more significant factor in treatment outcomes. To compare the clinical effect of using the maximum-size treatment beam available for each delivered fluence during laser tattoo removal to a standard 4-mm-diameter treatment beam. Thirteen tattoos were treated in 12 subjects using a Q-switched Nd:YAG laser equipped with a treatment beam diameter that was adjustable in 1 mm increments and a setting that would enable the maximally achievable diameter ("MAX-ON" setting) with any fluence. Tattoos were randomly bisected and treated on one side with the MAX-ON setting and on the contralateral side with a standard 4-mm-diameter spot ("MAX-OFF" setting). Photographs were taken 8 weeks following each treatment and each half-tattoo was evaluated for clearance on a 10-point scale by physicians blinded to the treatment conditions. Tattoo clearance was greater on the side treated with the MAX-ON setting in a statistically significant manner following the 1st through 4th treatments, with the MAX-OFF treatment site approaching the clearance of the MAX-ON treatment site after the 5th and 6th treatments. This high-energy, Q-switched Nd:YAG laser with a continuously variable spot-size safely and effectively removes tattoos, with greater removal when using a larger spot-size. © 2013 Wiley Periodicals, Inc.

Treatment of resistant tattoos using a new generation Q-switched Nd:YAG laser: influence of beam profile and spot size on clearance success.

PubMed

Karsai, Syrus; Pfirrmann, Gudrun; Hammes, Stefan; Raulin, Christian

2008-02-01

Multiple treatments of resistant tattoos often result in fibrosis and visible textural changes that lessen response to subsequent treatments. The aim of this study is to evaluate the influence of beam profile and spot size on clearance rates and side effects in the setting of resistant tattoos. Thirty-six professional, black tattoos (32 patients) were treated unsuccessfully with a Q-switched Nd:YAG laser (MedLite C3, HoyaConBio Inc., Fremont, CA). Because of therapy resistance all tattoos were re-treated using a new generation Nd:YAG laser (MedLite C6, HoyaConBio Inc.). Maximum energy fluence (E (max)), mean energy fluence, mean spot size, level of clearance, side effects and beam profile (irradiance distribution) of both laser systems were assessed and evaluated in a retrospective study. All tattoos were previously treated with the C3 laser at 1,064 nm using a mean E(max) of 5.8+/-0.8 J/cm(2) (range 3.8-7.5 J/cm(2)) as compared with a mean E(max) of 6.4+/-1.6 J/cm(2) (range 3.2-9.0 J/cm(2)) during the C6 treatment course. Corresponding spot sizes were larger during C6 treatments as compared with C3 (5.0+/-0.9 and 3.6+/-0.2 mm, respectively). The C6 laser had a "flat top" and homogenous profile regardless of the spot size. For the C3 laser the beam shape was "Gaussian," and the homogeneity was reduced by numerous micro-spikes and micro-nadirs. After the C6 treatment course 33.3% of the tattoos showed clearance of grade 1 (0-25%), 16.7% of grade 2 (26-50%), 16.7% of grade 3 (51-75%), 30.5% of grade 4 (76-95%), 2.8% of grade 5 (96-100%). The total rate of side effects due to C6 treatment was 8.3% in all tattoos (hyperpigmentation 5.6%, hypopigmentation 2.7%, textural changes/scars 0%). This clinical study documents for the first time the impact of a 1,064-nm Nd:YAG laser with a more homogenous beam profile and a larger spot size on the management of resistant tattoos. Only a few treatment sessions were necessary to achieve an additional clearance with a low rate of side effects.

Novel technique to treat melasma in Chinese: The combination of 2940-nm fractional Er:YAG and 1064-nm Q-switched Nd:YAG laser.

PubMed

Tian, Wei Cheng Brian Anthony

2016-01-01

Melasma is one of the most common pigmented lesions in Chinese women. Although topical therapies are the mainstay treatment, lasers are being used increasingly to treat pigmented lesions. Laser treatment of melasma is however still controversial. This is because lasers have not been able to produce complete clearance of melasma and recurrence rates are high. Laser treatments also cause complications such as hypopigmentation and post-inflammatory hyperpigmentation. In this article, we report on a novel technique using a combination of fractional 2940-nm Er:YAG and 1064-nm Q-switched Nd:YAG lasers. We achieved a rapid improvement in two cases of melasma in Chinese type III skin. The improvement was seen rapidly within a month of treatment. Follow-up at 6 months showed sustained results with no complications. This novel technique is able to safely confer excellent and sustained clearance within a short treatment time.

Tattoo Removal: Options and Results

MedlinePlus

... tattoos. In recent years, FDA has cleared for marketing several types of lasers for tattoo lightening or ... Mehmet Kosoglu, Ph.D., who reviews applications for marketing clearances of laser-devices. There are several FDA- ...

Indocyanine green-augmented diode laser therapy vs. long-pulsed Nd:YAG (1064 nm) laser treatment of telangiectatic leg veins: a randomized controlled trial.

PubMed

Klein, A; Buschmann, M; Babilas, P; Landthaler, M; Bäumler, W

2013-08-01

Telangiectatic leg veins (TLV) represent a common cosmetic problem. Near infrared lasers have been widely used in treatment because of their deeper penetration into the dermis, but with varying degrees of success, particularly because of different vessel diameters. Indocyanine green (ICG)-augmented diode laser treatment (ICG+DL) may present an alternative treatment option. This trial evaluates the efficacy of ICG+DL in the treatment of TLV and compares the safety and efficacy of therapy with the standard treatment, the long-pulsed neodymium-doped yttrium aluminium garnet (Nd:YAG) laser. In a prospective randomized controlled clinical trial, 29 study participants with TLV were treated with a Nd:YAG laser (λem = 1064 nm, 160-240 J cm(-2) , 65-ms pulse duration, 5-mm spot size) and ICG+DL (λem = 810 nm, 60-110 J cm(-2) , 48-87-ms pulse duration, 6-mm spot size; total ICG dose 4 mg kg(-1) ) in a side-by-side comparison in one single treatment setting that included histological examination in four participants. Two blinded investigators and the participants assessed clearance rate, cosmetic appearance and adverse events up to 3 months after treatment. According to both the investigators' and participants' assessment, clearance rates were significantly better after ICG+DL therapy than after Nd:YAG laser treatment (P < 0·05). On a 10-point scale indicating pain during treatment, participants rated ICG+DL therapy to be more painful (6·1 ± 2·0) than Nd:YAG laser (5·4 ± 2·0). ICG+DL therapy represents a new and promising treatment modality for TLV, with high clearance rates and a very good cosmetic outcome after one single treatment session. © 2013 British Association of Dermatologists.

Beam profile measurements for target designators

NASA Astrophysics Data System (ADS)

Frank, J. D.

1985-02-01

An American aerospace company has conducted a number of investigations with the aim to improve on the tedious slow manual methods of measuring pulsed lasers for rangefinders, giving particular attention to beam divergence which is studied by varying aperture sizes and positions in the laser beam path. Three instruments have been developed to make the involved work easier to perform. One of these, the Automatic Laser Instrumentation and Measurement System (ALIMS), consists of an optical bench, a digital computer, and three bays of associated electronic instruments. ALIMS uses the aperture method to measure laser beam alignment and divergence. The Laser Intensity Profile System (LIPS) consists of a covered optical bench and a two bay electronic equipment and control console. The Automatic Laser Test Set (ALTS) utilizes a 50 x 50 silicon photodiode array to characterize military laser systems automatically. Details regarding the conducted determinations are discussed.

Automatic brightness control of laser spot vision inspection system

NASA Astrophysics Data System (ADS)

Han, Yang; Zhang, Zhaoxia; Chen, Xiaodong; Yu, Daoyin

2009-10-01

The laser spot detection system aims to locate the center of the laser spot after long-distance transmission. The accuracy of positioning laser spot center depends very much on the system's ability to control brightness. In this paper, an automatic brightness control system with high-performance is designed using the device of FPGA. The brightness is controlled by combination of auto aperture (video driver) and adaptive exposure algorithm, and clear images with proper exposure are obtained under different conditions of illumination. Automatic brightness control system creates favorable conditions for positioning of the laser spot center later, and experiment results illuminate the measurement accuracy of the system has been effectively guaranteed. The average error of the spot center is within 0.5mm.

76 FR 53529 - Agency Information Collection Activities: Requests for Comments; Clearance of Renewed Approval of...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-26

... Laser Illumination of Aircraft AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice and... collection covers the reporting of unauthorized illumination of aircraft by lasers. DATES: Written comments.... Title: Reporting of Laser Illumination of Aircraft. Form Numbers: Advisory Circular 70-2. Type of Review...

Lesion strength control by automatic temperature guided retinal photocoagulation.

PubMed

Schlott, Kerstin; Koinzer, Stefan; Baade, Alexander; Birngruber, Reginald; Roider, Johann; Brinkmann, Ralf

2016-09-01

Laser photocoagulation is an established treatment for a variety of retinal diseases. However, when using the same irradiation parameter, the size and strength of the lesions are unpredictable due to unknown inter- and intraindividual optical properties of the fundus layers. The aim of this work is to investigate a feedback system to generate desired lesions of preselectable strengths by automatically controlling the irradiation time. Optoacoustics were used for retinal temperature monitoring. A 532-nm continuous wave Nd:YAG laser was used for photocoagulation. A 75-ns/523-nm Q-switched Nd:YLF laser simultaneously excited temperature-dependent pressure transients, which were detected at the cornea by an ultrasonic transducer embedded in a contact lens. The temperature data were analyzed during the irradiation by a LabVIEW routine. The treatment laser was switched off automatically when the required lesion strength was achieved. Five different feedback control algorithms for different lesion sizes were developed and tested on rabbits in vivo. With a laser spot diameter of 133???m, five different lesion types with ophthalmoscopically visible diameters ranging mostly between 100 and 200???m, and different appearances were achieved by automatic exposure time control. The automatically controlled lesions were widely independent of the treatment laser power and the retinal pigmentation.

Lesion strength control by automatic temperature guided retinal photocoagulation

NASA Astrophysics Data System (ADS)

Schlott, Kerstin; Koinzer, Stefan; Baade, Alexander; Birngruber, Reginald; Roider, Johann; Brinkmann, Ralf

2016-09-01

Laser photocoagulation is an established treatment for a variety of retinal diseases. However, when using the same irradiation parameter, the size and strength of the lesions are unpredictable due to unknown inter- and intraindividual optical properties of the fundus layers. The aim of this work is to investigate a feedback system to generate desired lesions of preselectable strengths by automatically controlling the irradiation time. Optoacoustics were used for retinal temperature monitoring. A 532-nm continuous wave Nd:YAG laser was used for photocoagulation. A 75-ns/523-nm Q-switched Nd:YLF laser simultaneously excited temperature-dependent pressure transients, which were detected at the cornea by an ultrasonic transducer embedded in a contact lens. The temperature data were analyzed during the irradiation by a LabVIEW routine. The treatment laser was switched off automatically when the required lesion strength was achieved. Five different feedback control algorithms for different lesion sizes were developed and tested on rabbits in vivo. With a laser spot diameter of 133 μm, five different lesion types with ophthalmoscopically visible diameters ranging mostly between 100 and 200 μm, and different appearances were achieved by automatic exposure time control. The automatically controlled lesions were widely independent of the treatment laser power and the retinal pigmentation.

Semi-automatic, octave-spanning optical frequency counter.

PubMed

Liu, Tze-An; Shu, Ren-Huei; Peng, Jin-Long

2008-07-07

This work presents and demonstrates a semi-automatic optical frequency counter with octave-spanning counting capability using two fiber laser combs operated at different repetition rates. Monochromators are utilized to provide an approximate frequency of the laser under measurement to determine the mode number difference between the two laser combs. The exact mode number of the beating comb line is obtained from the mode number difference and the measured beat frequencies. The entire measurement process, except the frequency stabilization of the laser combs and the optimization of the beat signal-to-noise ratio, is controlled by a computer running a semi-automatic optical frequency counter.

A Study on the Development of a Robot-Assisted Automatic Laser Hair Removal System

PubMed Central

Lim, Hyoung-woo; Park, Sungwoo; Noh, Seungwoo; Lee, Dong-Hun; Yoon, Chiyul; Koh, Wooseok; Kim, Youdan; Chung, Jin Ho; Kim, Hee Chan

2014-01-01

Abstract Background and Objective: The robot-assisted automatic laser hair removal (LHR) system is developed to automatically detect any arbitrary shape of the desired LHR treatment area and to provide uniform laser irradiation to the designated skin area. Methods: For uniform delivery of laser energy, a unit of a commercial LHR device, a laser distance sensor, and a high-resolution webcam are attached at the six axis industrial robot's end-effector, which can be easily controlled using a graphical user interface (GUI). During the treatment, the system provides real-time treatment progress as well as the total number of “pick and place” automatically. Results: During the test, it was demonstrated that the arbitrary shapes were detected, and that the laser was delivered uniformly. The localization error test and the area-per-spot test produced satisfactory outcome averages of 1.04 mm error and 38.22 mm2/spot, respectively. Conclusions: Results showed that the system successfully demonstrated accuracy and effectiveness. The proposed system is expected to become a promising device in LHR treatment. PMID:25343281

A study on the development of a robot-assisted automatic laser hair removal system.

PubMed

Lim, Hyoung-Woo; Park, Sungwoo; Noh, Seungwoo; Lee, Dong-Hun; Yoon, Chiyul; Koh, Wooseok; Kim, Youdan; Chung, Jin Ho; Kim, Hee Chan; Kim, Sungwan

2014-11-01

Abstract Background and Objective: The robot-assisted automatic laser hair removal (LHR) system is developed to automatically detect any arbitrary shape of the desired LHR treatment area and to provide uniform laser irradiation to the designated skin area. For uniform delivery of laser energy, a unit of a commercial LHR device, a laser distance sensor, and a high-resolution webcam are attached at the six axis industrial robot's end-effector, which can be easily controlled using a graphical user interface (GUI). During the treatment, the system provides real-time treatment progress as well as the total number of "pick and place" automatically. During the test, it was demonstrated that the arbitrary shapes were detected, and that the laser was delivered uniformly. The localization error test and the area-per-spot test produced satisfactory outcome averages of 1.04 mm error and 38.22 mm(2)/spot, respectively. RESULTS showed that the system successfully demonstrated accuracy and effectiveness. The proposed system is expected to become a promising device in LHR treatment.

Comparison of Bite Registration Material Accuracy on in office Laser Scanned Digital Model Occlusion

DTIC Science & Technology

2014-05-20

School/Department/Center: Two Year Advanced Education in General Dentistry . Fort Bragg,NC 4. Phone:910-429-6626 5. Type of clearance: _X_Paper...Date: 11.~ l~ 4. Higher approval clearance required (for University-, DoD- or US Gov’t-level policy, communication systems or weapons issues review...or US Gov’t-level policy, communications systems or weapons issues review). *Note: It is DoD policy that clearance of information or material

Use of Q-switched alexandrite laser (755 nm, 100 nsec) for removal of traumatic tattoo of different origins.

PubMed

Moreno-Arias, G A; Casals-Andreu, M; Camps-Fresneda, A

1999-01-01

Q-switched laser systems have been used for removal of tattoo-related carbon, graphite, and other particles. We assessed elimination of traumatic tattoos of different origin with Q-switched alexandrite laser in nine patients. Fluence threshold was determined and a spot test was made. Q-switched alexandrite laser, with a fluence range 4.5-8.0 J/cm(2) (mean, 7.16 +/- 1.18), was used at 4-5-week intervals. Total treatment ranged from 3-12 sessions (mean, 6.1 +/- 3.6 sessions). Double-pulse technique was used in black/black-bluish areas, but single-shot was applied to slate-gray pigment. More than 95% lightening was achieved in five patients after 5.2 +/- 2.3 sessions, and >75% lightening in six subjects after 6.1 +/- 3.1 sessions of treatment. Blacktop, surgical pen, and gravel tattoos presented a better response than gunpowder/fireworks tattoos (>95% vs. 68.7 +/- 23.9% clearance), or tattoos of unknown origin (>95% vs. 62.5 +/- 53% clearance). Epidermal splattering and pinpoint bleeding were observed in one case. No pigmentary alteration or scarring was seen. The Q-switched alexandrite laser is a useful system for removal of traumatic tattoos of diverse origin. The best response (>95% clearance) was achieved in blacktop, surgical pen, and gravel tattoos, although an acceptable degree of lightening may be obtained in tattoos due to gunpowder or fireworks. Copyright 1999 Wiley-Liss, Inc.

RANGE INCREASER FOR PNEUMATIC GAUGES

DOEpatents

Fowler, A.H.; Seaborn, G.B. Jr.

1960-09-27

An improved pneumatic gage is offered in which the linear range has been increased without excessive air consumption. This has been accomplished by providing an expansible antechamber connected to the nozzle of the gage so that the position of the nozzle with respect to the workpiece is varied automatically by variation in pressure within the antechamber. This arrangement ensures that the nozzle-to-workpiece clearance is maintained within certain limits, thus obtaining a linear relation of air flow to nozzle-to-workpiece clearance over a wider range.

Image-guided automatic triggering of a fractional CO2 laser in aesthetic procedures.

PubMed

Wilczyński, Sławomir; Koprowski, Robert; Wiernek, Barbara K; Błońska-Fajfrowska, Barbara

2016-09-01

Laser procedures in dermatology and aesthetic medicine are associated with the need for manual laser triggering. This leads to pulse overlapping and side effects. Automatic laser triggering based on image analysis can provide a secure fit to each successive doses of radiation. A fractional CO2 laser was used in the study. 500 images of the human skin of healthy subjects were acquired. Automatic triggering was initiated by an application together with a camera which tracks and analyses the skin in visible light. The tracking algorithm uses the methods of image analysis to overlap images. After locating the characteristic points in analysed adjacent areas, the correspondence of graphs is found. The point coordinates derived from the images are the vertices of graphs with respect to which isomorphism is sought. When the correspondence of graphs is found, it is possible to overlap the neighbouring parts of the image. The proposed method of laser triggering owing to the automatic image fitting method allows for 100% repeatability. To meet this requirement, there must be at least 13 graph vertices obtained from the image. For this number of vertices, the time of analysis of a single image is less than 0.5s. The proposed method, applied in practice, may help reduce the number of side effects during dermatological laser procedures resulting from laser pulse overlapping. In addition, it reduces treatment time and enables to propose new techniques of treatment through controlled, precise laser pulse overlapping. Copyright © 2016 Elsevier Ltd. All rights reserved.

An accurate laser radiometer for determining visible exposure times.

PubMed

Royston, D D

1985-01-01

A laser light radiometer has been developed for the Electro-Optics Branch of the Center for Devices and Radiological Health (CDRH). The radiometer measures direct laser radiation emitted in the visible spectrum. Based upon this measurement, the instrument's microprocessor automatically determines at what time duration the exposure to the measured laser radiation would exceed either the class I accessible emission limits of the Federal Performance Standard for laser products or the maximum permissible exposure limits of laser user safety standards. The instrument also features automatic background level compensation, pulse measurement capability, and self-diagnosis. Measurement of forward surface illumination levels preceding HpD photoradiation therapy is possible.

Combination of Electronic Choledochoscopy and Holmium Laser Lithotripsy for Complicated Biliary Calculus Treatment: A New Exploration.

PubMed

Ni, Zhong-Kai; Jin, Hai-Min; Li, Xiao-Wen; Li, Ye; Huang, Hai

2018-06-01

The safety and efficacy of the combination of electronic choledochoscopy and holmium laser lithotripsy for complicated bile duct stones were assessed. In total, 20 patients participated in this study, which was conducted between 2012 and 2017. None of the patients were candidates for endoscopic retrograde cholangiopancreatography with stone extraction. Outcome measures included complete stone clearance and complications postprocedure. Mean stone size was 17±5.2 mm (8 to 30 mm) and mean number of stones was 1.7±1.3 (1 to 5). The mean number of laser sessions was 1.3±0.7 (1 to 4). A mean of 1.0 to 1.5 J/20 to 25 Hz was applied during laser lithotripsy sessions with a mean operative time of 67.8±24.8 minutes. The clearance rate of stone was 18/20 (90%). No mortality existed in this study; however, 1 patient developed acute pancreatitis. The combination of holmium laser lithotripsy and electronic choledochoscopy for complicated biliary calculi is safe, reliable, and minimally invasive and has low residual stone rate.

Effective treatment of Hailey-Hailey disease with a long-pulsed (5 ms) alexandrite laser.

PubMed

Awadalla, Farah; Rosenbach, Alan

2011-08-01

Familial benign pemphigus (Hailey-Hailey disease) is often resistant to conventional treatments. This report describes a 35-year-old Asian American male with a 12-year history of recalcitrant Hailey-Hailey disease who was treated with a long-pulsed alexandrite laser. Fluences ranged from 12 to 20 J/cm with a 5-ms pulse duration (spot sizes: 10-15 mm). Cold air cooling was used during the sessions. There was 50% improvement noted after the first treatment. Within 10 treatments, there was 95% clearance. Complete resolution was achieved by the thirteenth treatment. The lesions have been clear or nearly clear (greater than 95%) for the past 2 years. Once clearance was achieved, five maintenance laser treatments were initiated at 3-month intervals and eventually discontinued for 12 months without relapse.

Method to improve the blade tip-timing accuracy of fiber bundle sensor under varying tip clearance

NASA Astrophysics Data System (ADS)

Duan, Fajie; Zhang, Jilong; Jiang, Jiajia; Guo, Haotian; Ye, Dechao

2016-01-01

Blade vibration measurement based on the blade tip-timing method has become an industry-standard procedure. Fiber bundle sensors are widely used for tip-timing measurement. However, the variation of clearance between the sensor and the blade will bring a tip-timing error to fiber bundle sensors due to the change in signal amplitude. This article presents methods based on software and hardware to reduce the error caused by the tip clearance change. The software method utilizes both the rising and falling edges of the tip-timing signal to determine the blade arrival time, and a calibration process suitable for asymmetric tip-timing signals is presented. The hardware method uses an automatic gain control circuit to stabilize the signal amplitude. Experiments are conducted and the results prove that both methods can effectively reduce the impact of tip clearance variation on the blade tip-timing and improve the accuracy of measurements.

An expanded study of long-pulsed 1064 nm Nd:YAG laser treatment of basal cell carcinoma.

PubMed

Ortiz, Arisa E; Anderson, R Rox; DiGiorgio, Catherine; Jiang, Shang I Brian; Shafiq, Faiza; Avram, Mathew M

2018-02-13

Basal cell carcinoma (BCC) is an indolent form of skin cancer that is rarely life threatening, but can cause significant cosmetic and functional morbidity. Surgical treatments often result in disfiguring scars, while topical therapies frequently result in recurrence. The need for a more effective nonsurgical alternative has led to the investigation of laser treatment of BCC. We have previously conducted a pilot study which showed 100% histologic clearance at high fluences. Treatments were well tolerated with no significant adverse events. The objective of this larger study was to confirm preliminary results that the 1064 nm Nd:YAG laser is a safe and effective method for treating non-facial BCC. This is an IRB-approved, prospective, multi-center study evaluating the safety and efficacy of the 1064 nm Nd:YAG laser for the treatment of BCC on the trunk and extremities. Thirty-three subjects seeking treatment for biopsy-proven BCC that did not meet the criteria for Mohs surgery were recruited. Subjects on current anticoagulation therapy, or with a history of immunosuppression were excluded. Subjects received one treatment with the 1064 nm Nd:YAG laser as follows: 5-6 mm spot, fluence of 125-140 J/cm 2 and a pulse duration of 7-10 ms. Standard excision with 5 mm clinical margins was performed at 30 days after laser treatment to evaluate clinical and histologic clearance of BCC. Standardized photographs and adverse assessments were taken at the baseline visit, immediately after laser treatment and on the day of excision. Thirty-one subjects completed the study. BCC tumors had a 90% (28 of 31 BCC tumors) histologic clearance rate after one treatment with the long-pulsed 1064 nm Nd:YAG laser. Treatments were generally well tolerated without any anesthesia. Immediate side effects included edema and erythema. At 1-month follow-up, some patients had residual crusting. No significant adverse events occurred. The 1064 nm long-pulsed Nd:YAG laser is an alternative for treating non-facial BCC for those that are poor surgical candidates. Lasers Surg. Med. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

A new airborne laser rangefinder dynamic target simulator for non-stationary environment

NASA Astrophysics Data System (ADS)

Ma, Pengge; Pang, Dongdong; Yi, Yang

2017-11-01

For the non-stationary environment simulation in laser range finder product testing, a new dynamic target simulation system is studied. First of all, the three-pulsed laser ranging principle, laser target signal composition and mathematical representation are introduced. Then, the actual nonstationary working environment of laser range finder is analyzed, and points out that the real sunshine background light clutter and target shielding effect in laser echo become the main influencing factors. After that, the dynamic laser target signal simulation method is given. Eventlly, the implementation of automatic test system based on arbitrary waveform generator is described. Practical application shows that the new echo signal automatic test system can simulate the real laser ranging environment of laser range finder, and is suitable for performance test of products.

Gain Coupling VECSELs (POSTPRINT)

DTIC Science & Technology

2013-01-01

International Conference on Molecular Beam Epitaxy (MBE-XV). 10. A. Siegman , Lasers , University Sciences Books, 1986. 11. C. Hessenius, N. Terry, M...Clearance Date 28 December 2012. Report contains color. 14. ABSTRACT Vertical external cavity surface emitting lasers (VECSELs) provide a flexible...platform in order to explore curious laser designs and systems as their high-power, high-brightness make them attractive for many applications, and their

Treatment of facial telangiectasias with a diode-pumped Nd:YAG laser at 532 nm

NASA Astrophysics Data System (ADS)

Cassuto, Daniel A.; Ancona, Deborah M.; Emanuelli, Guglielmo

2000-06-01

Facial telangiectasias are a common cause of cosmetic concern. Current treatment modalities present various effects and limits. The pulsed dye laser has been considered the golden standard in efficacy and safety. Unfortunately it causes postoperative intracutaneous hematomata that discourage many patients form undergoing this treatment. Several other vascular lasers are disadvantaged by the risk of hypopigmented and atrophic scars. We assessed a recent powerful version of the potassium titanyl phosphate 532 nm laser, that can deliver sufficient energy in single pulses lasting 10-50 msec. Collateral damage is reduced while the heating of the vessel is slow enough to avoid explosive photothermolysis with its associated purpura. Sixty-six patients with facial telangiectasias were treated. In 62/66 patients, we achieved a 75 percent-100 percent clearance of the lesions, while two treatments were needed to reach an acceptable clearance in the remaining 4/66 patients. The overall need for more sessions was well tolerated, because the acceptable postoperative appearance allowed patients to continue normal business and social activities between treatments. No permanent complications or undesired effects were noted. The KTP/532nm laser is also being tested in combined laser-sclerotherapy of fine leg capillary telangiectasias with encouraging results.

Comparison of treatment with an Alexandrite picosecond laser and Nd:YAG nanosecond laser for removing blue-black Chinese eyeliner tattoos.

PubMed

Zhang, Mengli; Huang, Yuqing; Lin, Tong; Wu, Qiuju

2018-02-28

To retrospectively evaluate the efficacy of an Alexandrite picosecond laser versus Nd:YAG nanosecond laser for removing blue-black eyeliner tattoos which have existed more than 10 years. A total of 40 patients were treated with an Alexandrite picosecond laser in our department from August 2015 to July 2017, with a fluence of 1.96-6.37J/cm 2 , spot size of 2.0-3.6 mm, and pulse width of 750 ps. Another 32 patients were treated with an Nd:YAG nanosecond laser, with a fluence of 2.80-7.00 J/cm 2 , spot size of 3 mm, and pulse width of 5-20 ns. All analysed patients completed at least one treatment and follow-up. The median number of treatment for all the patients was 1 (range, 1-4). After a single session, no difference was found between the two lasers for the eyeliner removal (p > 0.05). For the people who achieved an excellent response of tattoo clearance, there was still no difference between the two groups (p > 0.05). Transient side effects were observed in two groups, but neither group had significant adverse reactions. To treat blue-black Chinese eyeliner tattoos over 10 years, Alexandrite picosecond laser does not provide better clearance than the Nd:YAG nanosecond laser.

Regulation and Measurement of the Heat Generated by Automatic Tooth Preparation in a Confined Space.

PubMed

Yuan, Fusong; Zheng, Jianqiao; Sun, Yuchun; Wang, Yong; Lyu, Peijun

2017-06-01

The aim of this study was to assess and regulate heat generation in the dental pulp cavity and circumambient temperature around a tooth during laser ablation with a femtosecond laser in a confined space. The automatic tooth preparing technique is one of the traditional oral clinical technology innovations. In this technique, a robot controlled an ultrashort pulse laser to automatically complete the three-dimensional teeth preparing in a confined space. The temperature control is the main measure for protecting the tooth nerve. Ten tooth specimens were irradiated with a femtosecond laser controlled by a robot in a confined space to generate 10 teeth preparation. During the process, four thermocouple sensors were used to record the pulp cavity and circumambient environment temperatures with or without air cooling. A statistical analysis of the temperatures was performed between the conditions with and without air cooling (p < 0.05). The recordings showed that the temperature with air cooling was lower than that without air cooling and that the heat generated in the pulp cavity was lower than the threshold for dental pulp damage. These results indicate that femtosecond laser ablation with air cooling might be an appropriate method for automatic tooth preparing.

Efficacy of percutaneous treatment of biliary tract calculi using the holmium:YAG laser.

PubMed

Hazey, J W; McCreary, M; Guy, G; Melvin, W S

2007-07-01

Few Western studies have focused on percutaneous techniques using percutaneous transhepatic choledochoscopy (PTHC) and holmium:yttrium-aluminum-garnet (YAG) laser to ablate biliary calculi in patients unable or unwilling to undergo endoscopic or surgical removal of the calculi. The authors report the efficacy of the holmium:YAG laser in clearing complex biliary calculi using percutaneous access techniques. This study retrospectively reviewed 13 non-Asian patients with complex secondary biliary calculi treated percutaneously using holmium:YAG laser. Percutaneous access was accomplished via left, right, or bilateral hepatic ducts and upsized for passage of a 7-Fr video choledochoscope. Lithotripsy was performed under choledochoscopic vision using a holmium:YAG laser with 200- or 365-microm fibers generating 0.6 to 1.0 joules at 8 to 15 Hz. Patients underwent treatment until stone clearance was confirmed by PTHC. Downsizing and subsequent removal of percutaneous catheters completed the treatment course. Seven men and six women with an average age of 69 years underwent treatment. All the patients had their biliary tract stones cleared successfully. Of the 13 patients, 3 were treated solely as outpatients. The average length of percutaneous access was 108 days. At this writing, one patient still has a catheter in place. The average number of holmium:YAG laser treatments required for stone clearance was 1.6, with no patients requiring more than 3 treatments. Of the 13 patients, 8 underwent a single holmium:YAG laser treatment to clear their calculi. Prior unsuccessful attempts at endoscopic removal of the calculi had been experienced by 7 of the 13 patients. Five patients underwent percutaneous access and subsequent stone removal as their sole therapy for biliary stones. Five patients were cleared of their calculi after percutaneous laser ablation of large stones and percutaneous basket retrieval of the remaining stone fragments. There was one complication of pain requiring admission, and no deaths. The use of PTHC with holmium:YAG laser ablation is safe and efficacious, but requires prolonged biliary access and often multiple procedures to ensure clearance of all calculi.

Blade tip clearance measurement of the turbine engines based on a multi-mode fiber coupled laser ranging system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Haotian; Duan, Fajie; Wu, Guoxiu

2014-11-15

The blade tip clearance is a parameter of great importance to guarantee the efficiency and safety of the turbine engines. In this article, a laser ranging system designed for blade tip clearance measurement is presented. Multi-mode fiber is utilized for optical transmission to guarantee that enough optical power is received by the sensor probe. The model of the tiny sensor probe is presented. The error brought by the optical path difference of different modes of the fiber is estimated and the length of the fiber is limited to reduce this error. The measurement range in which the optical power receivedmore » by the probe remains essentially unchanged is analyzed. Calibration experiments and dynamic experiments are conducted. The results of the calibration experiments indicate that the resolution of the system is about 0.02 mm and the range of the system is about 9 mm.« less

Long-term evaluation of ink clearance in tattoos with different color intensity using the 1064-nm Q-switched Nd:YAG laser.

PubMed

Mankowska, Agata; Kasprzak, Wojciech; Adamski, Zygmunt

2015-12-01

The aim of the study was to evaluate the efficacy of tattoo removal treatments using the 1064-nm Q-switched (QS) Nd:YAG laser. Today, QS lasers appear to be the most common, effective, and safest methods to treat unwanted markings. A total of 64 patients with 75 unwanted tattoos were enrolled in the study. Tattoo clearance was evaluated according to the color intensity - concentration of pigment: group I (34) - black; group II (41) - gray. Consideration included methods of tattooing and tattoo techniques. In group I, after the first treatment session the median of clearance was 30% (10-50%), while in group II, the median was 50% (40-70%). After the second treatment session, median in group I increased to 40% (30-50%). Median of group II increased to 70% (50-80%). The highest number of treatment in group I was 7. After that, the median grew to 75%, while the highest amount of treatment in group II was 5 and a median of 90% was achieved. Effects were dependent upon the amount of ink deposited in the tissue. Old amateur tattoos and tattoos containing small quantities of ink (technique: shading and lines) demonstrated the quickest and the most efficacious results. Tattoos with large quantities of ink, obtained by filling, required the greatest number of treatment sessions. The final outcome in tattoo clearing can only be assessed following treatment completion, which may in some cases take 2-3 years. Presumably, in some cases, complete clearance is impossible. © 2015 Wiley Periodicals, Inc.

Temperature controlled retinal photocoagulation

NASA Astrophysics Data System (ADS)

Schlott, Kerstin; Koinzer, Stefan; Baade, Alexander; Birngruber, Reginald; Roider, Johann; Brinkmann, Ralf

2013-06-01

Retinal photocoagulation lacks objective dosage in clinical use, thus the commonly applied lesions are too deep and strong, associated with pain reception and the risk of visual field defects and induction of choroidal neovascularisations. Optoacoustics allows real-time non-invasive temperature measurement in the fundus during photocoagulation by applying short probe laser pulses additionally to the treatment radiation, which excite the emission of ultrasonic waves. Due to the temperature dependence of the Grüneisen parameter, the amplitudes of the ultrasonic waves can be used to derive the temperature of the absorbing tissue. By measuring the temperatures in real-time and automatically controlling the irradiation by feedback to the treatment laser, the strength of the lesions can be defined. Different characteristic functions for the time and temperature dependent lesion sizes were used as rating curves for the treatment laser, stopping the irradiation automatically after a desired lesion size is achieved. The automatically produced lesion sizes are widely independent of the adjusted treatment laser power and individual absorption. This study was performed on anaesthetized rabbits and is a step towards a clinical trial with automatically controlled photocoagulation.

Automatic control system of high precision welding of workpieces in mechanical engineering

NASA Astrophysics Data System (ADS)

Kuznetsov, I. N.; Zvezdin, V. V.; Israfilov, I. H.; Portnov, S. M.

2014-12-01

In this paper, based on the conducted patent research, the system of laser welding control with different geometry of weld and shapes of parts is developed. The method of monitoring the position of the spot of laser radiation in relation to the curved weld is worked out; it is based on the tracking the edges of the welded parts by low-power laser radiation reflected from the surface of the parts. It allows to make the positioning of the focus of laser radiation in relation to the juncture of the welded parts automatically.

Treating onychomycoses of the toenail: clinical efficacy of the sub-millisecond 1,064 nm Nd: YAG laser using a 5 mm spot diameter.

PubMed

Kimura, Utako; Takeuchi, Kaori; Kinoshita, Ayako; Takamori, Kenji; Hiruma, Masataro; Suga, Yasushi

2012-04-01

Onychomycosis is a relatively common fungal infection. Current treatments have limited applicability and low cure rates. Recently introduced laser therapy has shown to be a safe and effective treatment for onychomycosis. In this study, we evaluate a submillisecond Nd:YAG 1,064 nm laser for treating onychomycoses of the tonail. Thirteen subjects (9 female, 4 male) with 37 affected toenails received 1 to 3 treatments 4 and/or 8 weeks apart with a sub-millisecond 1,064 nm Nd:YAG laser. Diagnosis of onychomycosis was confirmed with microscopy. Average follow-up time was 16 weeks post-final treatment. Photos were taken and degree of turbidity was determined using a turbidity scale (ranging from "0 = clear nail" to "10 = completely turbid nail") at each visit. Improvement in turbidity was determined by comparison of turbidity scores at baseline and 16-week follow-up on average. Efficacy was assessed by an overall improvement scale (0 to 4), which combined improvement in turbidity scores and microscopic examination. Overall improvement was classified as "4 = complete clearance" if the turbidity score indicated "0 = clear nail" accompanied by a negative microscopic result. No microscopic examination was performed unless the turbidity score showed "0 = clear nail." Treatments were well tolerated by all subjects and there were no adverse events. Of the 37 toenails treated, 30 (81%) had "moderate" to "complete" clearance average of 16 weeks post-final treatment. Nineteen toenails (51%) were completely clear and all tested negative for fungal infection on direct microscopic analysis. Seven (19%) toenails had significant clearance and four (11%) had moderate clearance. The preliminary results of this study show this treatment modality is safe and effective for the treatment of onychomycosis in the short term. Additional studies are needed to more fully assess the clinical and mycological benefits as well as optimize the treatment protocol and parameters.

Laser beam alignment apparatus and method

DOEpatents

Gruhn, C.R.; Hammond, R.B.

The disclosure related to an apparatus and method for laser beam alignment. Thermoelectric properties of a disc in a laser beam path are used to provide an indication of beam alignment and/or automatic laser alignment.

Laser beam alignment apparatus and method

DOEpatents

Gruhn, Charles R.; Hammond, Robert B.

1981-01-01

The disclosure relates to an apparatus and method for laser beam alignment. Thermoelectric properties of a disc in a laser beam path are used to provide an indication of beam alignment and/or automatic laser alignment.

Ginsenoside compound K promotes β-amyloid peptide clearance in primary astrocytes via autophagy enhancement.

PubMed

Guo, Jinhui; Chang, Li; Zhang, Xin; Pei, Sujuan; Yu, Meishuang; Gao, Jianlian

2014-10-01

The aim of the present study was to investigate the effect of ginsenoside compound K on β-amyloid (Aβ) peptide clearance in primary astrocytes. Aβ degradation in primary astrocytes was determined using an intracellular Aβ clearance assay. Aggregated LC3 in astrocyte cells, which is a marker for the level of autophagy, was detected using laser scanning confocal microscope. The effect of compound K on the mammalian target of rapamycin (mTOR)/autophagy pathway was determined using western blot analysis, and an enzyme-linked immunosorbent assay was used for Aβ detection. The results demonstrated that compound K promoted the clearance of Aβ and enhanced autophagy in primary astrocytes. In addition, it was found that phosphorylation of mTOR was inhibited by compound K, which may have contributed to the enhanced autophagy. In conclusion, compound K promotes Aβ clearance by enhancing autophagy via the mTOR signaling pathway in primary astrocytes.

Automatic concrete cracks detection and mapping of terrestrial laser scan data

NASA Astrophysics Data System (ADS)

Rabah, Mostafa; Elhattab, Ahmed; Fayad, Atef

2013-12-01

Terrestrial laser scanning has become one of the standard technologies for object acquisition in surveying engineering. The high spatial resolution of imaging and the excellent capability of measuring the 3D space by laser scanning bear a great potential if combined for both data acquisition and data compilation. Automatic crack detection from concrete surface images is very effective for nondestructive testing. The crack information can be used to decide the appropriate rehabilitation method to fix the cracked structures and prevent any catastrophic failure. In practice, cracks on concrete surfaces are traced manually for diagnosis. On the other hand, automatic crack detection is highly desirable for efficient and objective crack assessment. The current paper submits a method for automatic concrete cracks detection and mapping from the data that was obtained during laser scanning survey. The method of cracks detection and mapping is achieved by three steps, namely the step of shading correction in the original image, step of crack detection and finally step of crack mapping and processing steps. The detected crack is defined in a pixel coordinate system. To remap the crack into the referred coordinate system, a reverse engineering is used. This is achieved by a hybrid concept of terrestrial laser-scanner point clouds and the corresponding camera image, i.e. a conversion from the pixel coordinate system to the terrestrial laser-scanner or global coordinate system. The results of the experiment show that the mean differences between terrestrial laser scan and the total station are about 30.5, 16.4 and 14.3 mms in x, y and z direction, respectively.

Detection of defects in laser powder deposition (LPD) components by pulsed laser transient thermography

NASA Astrophysics Data System (ADS)

Santospirito, S. P.; Słyk, Kamil; Luo, Bin; Łopatka, Rafał; Gilmour, Oliver; Rudlin, John

2013-05-01

Detection of defects in Laser Powder Deposition (LPD) produced components has been achieved by laser thermography. An automatic in-process NDT defect detection software system has been developed for the analysis of laser thermography to automatically detect, reliably measure and then sentence defects in individual beads of LPD components. A deposition path profile definition has been introduced so all laser powder deposition beads can be modeled, and the inspection system has been developed to automatically generate an optimized inspection plan in which sampling images follow the deposition track, and automatically control and communicate with robot-arms, the source laser and cameras to implement image acquisition. Algorithms were developed so that the defect sizes can be correctly evaluated and these have been confirmed using test samples. Individual inspection images can also be stitched together for a single bead, a layer of beads or multiple layers of beads so that defects can be mapped through the additive process. A mathematical model was built up to analyze and evaluate the movement of heat throughout the inspection bead. Inspection processes were developed and positional and temporal gradient algorithms have been used to measure the flaw sizes. Defect analysis is then performed to determine if the defect(s) can be further classified (crack, lack of fusion, porosity) and the sentencing engine then compares the most significant defect or group of defects against the acceptance criteria - independent of human decisions. Testing on manufactured defects from the EC funded INTRAPID project has successful detected and correctly sentenced all samples.

MATILDA Version 2: Rough Earth TIALD Model for Laser Probabilistic Risk Assessment in Hilly Terrain - Part I

DTIC Science & Technology

2017-03-13

support of airborne laser designator use during test and training exercises on military ranges. The initial MATILDA tool, MATILDA PRO Version-1.6.1...was based on the 2007 PRA model developed to perform range safety clearances for the UK Thermal Imaging Airborne Laser Designator (TIALD) system...AFRL Technical Reports. This Technical Report, designated Part I, con- tains documentation of the computational procedures for probabilistic fault

Automatic laser welding and milling with in situ inline coherent imaging.

PubMed

Webster, P J L; Wright, L G; Ji, Y; Galbraith, C M; Kinross, A W; Van Vlack, C; Fraser, J M

2014-11-01

Although new affordable high-power laser technologies enable many processing applications in science and industry, depth control remains a serious technical challenge. In this Letter we show that inline coherent imaging (ICI), with line rates up to 312 kHz and microsecond-duration capture times, is capable of directly measuring laser penetration depth, in a process as violent as kW-class keyhole welding. We exploit ICI's high speed, high dynamic range, and robustness to interference from other optical sources to achieve automatic, adaptive control of laser welding, as well as ablation, achieving 3D micron-scale sculpting in vastly different heterogeneous biological materials.

Application research of rail transit safety protection based on laser detection

NASA Astrophysics Data System (ADS)

Wang, Zhifei

2016-10-01

Platform screen door can not only prevent the passengers fell or jumped the track danger, to passengers bring comfortable waiting environment, but also has the function of environmental protection and energy saving. But platform screen door and train the full-length gap region is insecure in the system design of a hidden, such as passengers for some reason (grab the train) in the interstitial region retention, is sandwiched between the intercity safety door and the door, and such as the region lacks security detection and alarm system, once the passengers in the gap region retention (caught), bring more serious threat to the safety of passengers and traffic safety. This paper from the point of view of the design presents the physical, infrared, laser three safety protection device setting schemes. Domestic intelligence of between rail transit shield door and train security clearance processing used is screen door system standard configuration, the obstacle detection function for avoid passengers stranded in the clearance has strong prevention function. Laser detection research and development projects can access to prevent shield door and train gap clamp safety measures. Rail safety protection method are studied applying laser detection technique. According to the laser reflection equation of foreign body, the characteristics of laser detection of foreign bodies are given in theory. By using statistical analysis method, the workflow of laser detection system is established. On this basis, protection methods is proposed. Finally the simulation and test results show that the laser detection technology in the rail traffic safety protection reliability and stability, And the future laser detection technology in is discussed the development of rail transit.

Human-in-the-Loop Assessment of Alternative Clearances in Interval Management Arrival Operations

NASA Technical Reports Server (NTRS)

Baxley, Brian T.; Wilson, Sara R.; Swieringa, Kurt A.; Johnson, William C.; Roper, Roy D.; Hubbs, Clay E.; Goess, Paul A.; Shay, Richard F.

2016-01-01

Interval Management Alternative Clearances (IMAC) was a human-in-the-loop simulation experiment conducted to explore the Air Traffic Management (ATM) Technology Demonstration (ATD-1) Concept of Operations (ConOps), which combines advanced arrival scheduling, controller decision support tools, and aircraft avionics to enable multiple time deconflicted, efficient arrival streams into a high-density terminal airspace. Interval Management (IM) is designed to support the ATD-1 concept by having an "Ownship" (IM-capable) aircraft achieve or maintain a specific time or distance behind a "Target" (preceding) aircraft. The IM software uses IM clearance information and the Ownship data (route of flight, current location, and wind) entered by the flight crew, and the Target aircraft's Automatic Dependent Surveillance-Broadcast state data, to calculate the airspeed necessary for the IM-equipped aircraft to achieve or maintain the assigned spacing goal.

Optoacoustic temperature determination and automatic coagulation control in rabbits

NASA Astrophysics Data System (ADS)

Schlott, Kerstin; Koinzer, Stefan; Ptaszynski, Lars; Luft, Susanne; Baade, Alex; Bever, Marco; Roider, Johann; Birngruber, Reginald; Brinkmann, Ralf

2011-03-01

Retinal laser photocoagulation is an established treatment method for many retinal diseases like macula edema or diabetic retinopathy. The selection of the laser parameters is so far based on post treatment evaluation of the lesion size and strength. Due to local pigment variations in the fundus and individual transmission the same laser parameters often lead to an overtreatment. Optoacoustic allows a non invasive monitoring of the retinal temperature increase during retinal laser irradiation by measuring the temperature dependent pressure amplitudes, which are induced by short probe laser pulses. A 75 ns/ 523 nm Nd:YLF was used as a probe laser at a repetition rate of 1 kHz, and a cw / 532 nm treatment laser for heating. A contact lens was modified with a ring-shaped ultrasonic transducer to detect the pressure waves at the cornea. Temperatures were collected for irradiations leading to soft or invisible lesions. Based on this data the threshold for denaturation was found. By analyzing the initial temperature increase, the further temperature development during irradiation could be predicted. An algorithm was found to calculate the irradiation time, which is needed for a soft lesion formation, from the temperature curve. By this it was possible to provide a real-time dosimetry by automatically switching off the treatment laser after the calculated irradiation time. Automatically controlled coagulations appear softer and more uniformly.

Research on large spatial coordinate automatic measuring system based on multilateral method

NASA Astrophysics Data System (ADS)

Miao, Dongjing; Li, Jianshuan; Li, Lianfu; Jiang, Yuanlin; Kang, Yao; He, Mingzhao; Deng, Xiangrui

2015-10-01

To measure the spatial coordinate accurately and efficiently in large size range, a manipulator automatic measurement system which based on multilateral method is developed. This system is divided into two parts: The coordinate measurement subsystem is consists of four laser tracers, and the trajectory generation subsystem is composed by a manipulator and a rail. To ensure that there is no laser beam break during the measurement process, an optimization function is constructed by using the vectors between the laser tracers measuring center and the cat's eye reflector measuring center, then an orientation automatically adjust algorithm for the reflector is proposed, with this algorithm, the laser tracers are always been able to track the reflector during the entire measurement process. Finally, the proposed algorithm is validated by taking the calibration of laser tracker for instance: the actual experiment is conducted in 5m × 3m × 3.2m range, the algorithm is used to plan the orientations of the reflector corresponding to the given 24 points automatically. After improving orientations of some minority points with adverse angles, the final results are used to control the manipulator's motion. During the actual movement, there are no beam break occurs. The result shows that the proposed algorithm help the developed system to measure the spatial coordinates over a large range with efficiency.

Reflectance confocal microscopy-guided laser ablation of basal cell carcinomas: initial in vivo results

NASA Astrophysics Data System (ADS)

Sierra, Heidy; Cordova, Miguel; Yelamos, Oriol; Chen, Chih-Shan Jason; Rajadhyaksha, Milind

2017-02-01

Laser ablation offers a procedure for precise, fast and minimally invasive removal of superficial and early nodular basal cell carcinomas (BCCs). However, the lack of histopathological confirmation has been a limitation toward widespread use in the clinic. A reflectance confocal microscopy (RCM) imaging-guided laser ablation approach offers cellular-level histopathology-like feedback directly on the patient, which may guide and help improve the efficacy of this procedure. We performed an initial study on 44 BCCs on 21 patients in vivo (based in an ex vivo bench-top study reported in our earlier papers), using a pulsed erbium: ytterbium aluminum garnet laser and a contrast agent (aluminum chloride). Initial 10 lesions, the RCM imaging-guided detection of either presence of residual tumor or complete clearance was immediately confirmed with histopathology. Additionally, 34 BCCs on 15 patients were treated with RCM imaging-guided laser ablation, and the clearance of tumor is currently being monitored with follow-up imaging (i. e., no histopathology) at 3, 6 and 18 months. Thus far, the imaging resolution appears to be sufficient and consistent for monitoring efficacy in the wound, both immediately post-ablation and subsequently during recovery. The efficacy appears to be promising. However, further investigation and optimization to image over the entire wound (without missing any areas) need to be investigated.

Gated high speed optical detector

NASA Technical Reports Server (NTRS)

Green, S. I.; Carson, L. M.; Neal, G. W.

1973-01-01

The design, fabrication, and test of two gated, high speed optical detectors for use in high speed digital laser communication links are discussed. The optical detectors used a dynamic crossed field photomultiplier and electronics including dc bias and RF drive circuits, automatic remote synchronization circuits, automatic gain control circuits, and threshold detection circuits. The equipment is used to detect binary encoded signals from a mode locked neodynium laser.

Influence of Pelvicaliceal Anatomy on Stone Clearance After Flexible Ureteroscopy and Holmium Laser Lithotripsy for Large Renal Stones.

PubMed

Inoue, Takaaki; Murota, Takashi; Okada, Shinsuke; Hamamoto, Shuzo; Muguruma, Kouei; Kinoshita, Hidefumi; Matsuda, Tadashi

2015-09-01

This study was performed to evaluate the impact of pelvicaliceal anatomy on stone clearance in patients with remnant fragments in the lower pole after flexible ureteroscopy and holmium laser lithotripsy (fURSL) for renal stones >15 mm. This retrospective study included 67 patients with radiopaque residual fragments (>2 mm) in the lower pole after fURSL for large renal stones (>15 mm). The preoperative infundibular length (IL), infundibular width (IW), infundibulopelvic angle (IPA), and caliceal pelvic height (CPH) were measured using intravenous urography. Multivariate analysis was performed to determine whether any of these measurements affected stone clearance. Of the 67 patients, 55 (82.1%) were stone free (SF) 3 months after fURSL. The anatomic factors significantly favorable for an SF status were a short IL, broad IW, wide IPA, and low CPH. On multivariate analysis, the IPA had a significant influence on an SF status after fURSL (p=0.010). An IPA <30° was a negative risk factor (p=0.019). Postoperative complications occurred in nine patients (13.4%), including Clavien grade I complications in two patients (2.9%), grade II in six patients (8.9%), and grade IIIa in one patient (1.8%). Almost all complications were minor. An IPA <30° is the only negative risk factor for stone clearance after fURSL for large renal stones according to our multivariate analysis. Additional studies are required to further evaluate the characteristics of the pelvicaliceal anatomy influencing stone clearance.

The guidance methodology of a new automatic guided laser theodolite system

NASA Astrophysics Data System (ADS)

Zhang, Zili; Zhu, Jigui; Zhou, Hu; Ye, Shenghua

2008-12-01

Spatial coordinate measurement systems such as theodolites, laser trackers and total stations have wide application in manufacturing and certification processes. The traditional operation of theodolites is manual and time-consuming which does not meet the need of online industrial measurement, also laser trackers and total stations need reflective targets which can not realize noncontact and automatic measurement. A new automatic guided laser theodolite system is presented to achieve automatic and noncontact measurement with high precision and efficiency which is comprised of two sub-systems: the basic measurement system and the control and guidance system. The former system is formed by two laser motorized theodolites to accomplish the fundamental measurement tasks while the latter one consists of a camera and vision system unit mounted on a mechanical displacement unit to provide azimuth information of the measured points. The mechanical displacement unit can rotate horizontally and vertically to direct the camera to the desired orientation so that the camera can scan every measured point in the measuring field, then the azimuth of the corresponding point is calculated for the laser motorized theodolites to move accordingly to aim at it. In this paper the whole system composition and measuring principle are analyzed, and then the emphasis is laid on the guidance methodology for the laser points from the theodolites to move towards the measured points. The guidance process is implemented based on the coordinate transformation between the basic measurement system and the control and guidance system. With the view field angle of the vision system unit and the world coordinate of the control and guidance system through coordinate transformation, the azimuth information of the measurement area that the camera points at can be attained. The momentary horizontal and vertical changes of the mechanical displacement movement are also considered and calculated to provide real time azimuth information of the pointed measurement area by which the motorized theodolite will move accordingly. This methodology realizes the predetermined location of the laser points which is within the camera-pointed scope so that it accelerates the measuring process and implements the approximate guidance instead of manual operations. The simulation results show that the proposed method of automatic guidance is effective and feasible which provides good tracking performance of the predetermined location of laser points.

Materials processing by use of a Ti:Sapphire laser with automatically-adjustable pulse duration

NASA Astrophysics Data System (ADS)

Kamata, M.; Imahoko, T.; Ozono, K.; Obara, M.

We have developed an automatic pulsewidth-adjustable femtosecond Ti:Sapphire laser system that can generate an output of 50 fs-1 ps in duration, and sub-mJ/pulse at a repetition rate of 1 kpps. The automatic pulse compressor enables one to control the pulsewidth in the range of 50 fs-1 ps by use of a personal computer (PC). The compressor can change the distance in-between and the tilt angle of the grating pairs by use of two stepping motors and two piezo-electric transducer(PZT) driven actuators, respectively. Both are controlled by a PC. Therefore, not only control of the pulsewidth, but also of the optical chirp becomes easy. By use of this femtosecond laser system, we fabricated a waveguide in fused quartz. The numerical aperture is chosen to 0.007 to loosely focus the femtosecond laser. The fabricated waveguides are well controllable by the incident laser pulsewidth. We also demonstrated the ablation processing of hydroxyapatite (Ca10(PO4)6(OH)2), which is a key component of human tooth and human bone for orthopedics and dentistry. With pulsewidth tunable output from 50 fs through 2 ps at 1 kpps, the chemical content of calcium and phosphorus is kept unchanged before and after 50-fs-2-ps laser ablation. We also demonstrated the precise ablation processing of human tooth enamel with 2 ps Ti:Sapphire laser.

Automatic alignment of double optical paths in excimer laser amplifier

NASA Astrophysics Data System (ADS)

Wang, Dahui; Zhao, Xueqing; Hua, Hengqi; Zhang, Yongsheng; Hu, Yun; Yi, Aiping; Zhao, Jun

2013-05-01

A kind of beam automatic alignment method used for double paths amplification in the electron pumped excimer laser system is demonstrated. In this way, the beams from the amplifiers can be transferred along the designated direction and accordingly irradiate on the target with high stabilization and accuracy. However, owing to nonexistence of natural alignment references in excimer laser amplifiers, two cross-hairs structure is used to align the beams. Here, one crosshair put into the input beam is regarded as the near-field reference while the other put into output beam is regarded as the far-field reference. The two cross-hairs are transmitted onto Charge Coupled Devices (CCD) by image-relaying structures separately. The errors between intersection points of two cross-talk images and centroid coordinates of actual beam are recorded automatically and sent to closed loop feedback control mechanism. Negative feedback keeps running until preset accuracy is reached. On the basis of above-mentioned design, the alignment optical path is built and the software is compiled, whereafter the experiment of double paths automatic alignment in electron pumped excimer laser amplifier is carried through. Meanwhile, the related influencing factors and the alignment precision are analyzed. Experimental results indicate that the alignment system can achieve the aiming direction of automatic aligning beams in short time. The analysis shows that the accuracy of alignment system is 0.63μrad and the beam maximum restoration error is 13.75μm. Furthermore, the bigger distance between the two cross-hairs, the higher precision of the system is. Therefore, the automatic alignment system has been used in angular multiplexing excimer Main Oscillation Power Amplification (MOPA) system and can satisfy the requirement of beam alignment precision on the whole.

Automatic target alignment of the Helios laser system

NASA Astrophysics Data System (ADS)

Liberman, I.; Viswanathan, V. K.; Klein, M.; Seery, B. D.

1980-05-01

An automatic target-alignment technique for the Helios laser facility is reported and verified experimentally. The desired alignment condition is completely described by an autocollimation test. A computer program examines the autocollimated return pattern from the surrogate target and correctly describes any changes required in mirror orientation to yield optimum target alignment with either aberrated or misaligned beams. Automated on-line target alignment is thus shown to be feasible.

Stainless steel manual metal arc welding fumes in rats.

PubMed Central

Kalliomäki, P L; Lakomaa, E; Kalliomäki, K; Kiilunen, M; Kivelä, R; Vaaranen, V

1983-01-01

Forty two male Wistar rats were exposed to manual metal arc (MMA) stainless steel (SS) welding fumes generated by an automatic welding device for "nose-only" exposure. The exposure simulated an actual MMA/SS welding environment as closely as possible. For the retention study, the duration of exposure was one hour per workday for one, two, three, of four weeks and for the clearance study four weeks. The retention and clearance of the chromium, nickel, and iron found in MMA/SS welding fumes in the rats' lungs were studied as was the distribution of the metals to other organs. Instrumental neutron activation analysis (INAA) was used for the multi-element chemical activation analyses. The concentrations of chromium and nickel in the blood and the urine were determined by atomic absorption method (AAS). The retention of exogenous iron was determined by a magnetic measuring method. The results indicated that the lungs were the target organs of soluble hexavalent chromates. The half times of lung clearance for Cr, Ni, and Fe were 40 +/- 4 d, 20 +/- d, and 50 +/- 10 d. When the lung clearance curves are compared, the half times of Cr and Fe lung clearance are similar but nickel disappears faster. The distribution and clearance patterns of chromium to other organs differ from those obtained after single intravenous or intratracheal injections of alkaline chromates. PMID:6830723

78 FR 23626 - Agency Information Collection Activities; Requests for Comments; Clearance of Renewed Approval of...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-19

... Dependent Surveillance--Broadcast (ADS-B) Out Performance Requirements To Support Air Traffic Control (ATC.... The final rule titled ``Automatic Dependent Surveillance-- Broadcast (ADS-B) Equipage Mandate To... System. The rule facilitates the use of ADS-B for aircraft surveillance by FAA air traffic controllers to...

Comparison of two picosecond lasers to a nanosecond laser for treating tattoos: a prospective randomized study on 49 patients.

PubMed

Lorgeou, A; Perrillat, Y; Gral, N; Lagrange, S; Lacour, J-P; Passeron, T

2018-02-01

Q-switched nanosecond lasers demonstrated their efficacy in treating most types of tattoos, but complete disappearance is not always achieved even after performing numerous laser sessions. Picosecond lasers are supposed to be more efficient in clearing tattoos than nanosecond lasers, but prospective comparative data remain limited. To compare on different types of tattoos the efficacy of a nanosecond laser with two types of picosecond lasers. We conducted a prospective randomized study performed from December 2014 to June 2016 on adult patients with all types of tattoos. The tattoos were divided into two halves of equal size. After randomization, half of the tattoo was treated with a picosecond laser and the other half with a nanosecond laser. The evaluation was performed on standardized pictures performed before treatment and 2 months after the last session, by two physicians, not involved in the treatment, blinded on the type of treatments received. The main end point was a clearance above 75% of the tattoos. A total of 49 patients were included. Professional tattoos represented 85.7%, permanent make-up 8.2% and non-professional tattoo 6.1%. The majority were black or blue and 10.2% were polychromatic. No patient was lost during follow-up. A reduction of 75% or more of the colour intensity was obtained for 33% of the tattoos treated with the picosecond lasers compared to 14% with the nanosecond laser (P = 0.008). An improvement superior to 75% was obtained in 34% monochromic black or blue tattoos with the picosecond lasers compared to 9% for the nanosecond laser. Only one of the five polychromic tattoos achieved more than 75% of improvement with the two types of laser. Our results show a statistically significant superiority of the picosecond lasers compared to the nanosecond laser for tattoo clearance. However, they do not show better efficacy for polychromic tattoos and the difference in terms of side-effects was also minimal with a tendency of picosecond lasers to be less painful. © 2017 European Academy of Dermatology and Venereology.

Choledochoscopic Holmium Laser Lithotripsy for Difficult Bile Duct Stones.

PubMed

Lv, Shangdong; Fang, Zheping; Wang, Aidong; Yang, Jian; Zhang, Wenlong

2017-01-01

The aim of this study was to evaluate the feasibility and efficacy of choledochoscopic holmium laser lithotripsy as a means of removing resistant extrahepatic and intrahepatic bile duct stones. Clinical data on 28 patients who had undergone choledochoscopic holmium laser lithotripsy were analyzed. Complete stone clearance was obtained in 24 patients; small numbers of residual stones in the left or right hepatic duct were found in 4 patients. No severe complications such as hemobilia and bile duct injuries occurred. Choledochoscopic holmium laser lithotripsy is a simple, safe, and effective treatment method for patients with resistant bile duct stones.

Automatic low-order aberrations compensator for a conduction-cooled end-pumped solid-state zigzag slab laser

NASA Astrophysics Data System (ADS)

Yu, Xin; Dong, Lizhi; Lai, Boheng; Yang, Ping; Wang, Shuai; Wang, Xun; Liu, Yong; Tang, Guomao; Xu, Bing

2017-11-01

In order to solve the problem of large low-order aberrations with solid-state zigzag slab lasers, an automatic compensator has been developed in this paper. In this compensator, three lenses are mounted on a motorized rail, whose positions can be obtained using ray tracing method based on the beam parameters detected by a wave-front sensor. The initial peak to valley (PV) values of the wave-front range up to several tens of microns. Both simulated and experimental results show that the PV values of the wave-front can be reduced to around 1 . 6 μm with the proposed automatic compensator.

In vivo wide-field multispectral scanning laser ophthalmoscopy–optical coherence tomography mouse retinal imager: longitudinal imaging of ganglion cells, microglia, and Müller glia, and mapping of the mouse retinal and choroidal vasculature

PubMed Central

Zhang, Pengfei; Zam, Azhar; Jian, Yifan; Wang, Xinlei; Li, Yuanpei; Lam, Kit S.; Burns, Marie E.; Sarunic, Marinko V.; Pugh, Edward N.; Zawadzki, Robert J.

2015-01-01

Abstract. Scanning laser ophthalmoscopy (SLO) and optical coherence tomography (OCT) provide complementary views of the retina, with the former collecting fluorescence data with good lateral but relatively low-axial resolution, and the latter collecting label-free backscattering data with comparable lateral but much higher axial resolution. To take maximal advantage of the information of both modalities in mouse retinal imaging, we have constructed a compact, four-channel, wide-field (∼50  deg) system that simultaneously acquires and automatically coregisters three channels of confocal SLO and Fourier domain OCT data. The scanner control system allows “zoomed” imaging of a region of interest identified in a wide-field image, providing efficient digital sampling and localization of cellular resolution features in longitudinal imaging of individual mice. The SLO is equipped with a “flip-in” spectrometer that enables spectral “fingerprinting” of fluorochromes. Segmentation of retina layers and en face display facilitate spatial comparison of OCT data with SLO fluorescence patterns. We demonstrate that the system can be used to image an individual retinal ganglion cell over many months, to simultaneously image microglia and Müller glia expressing different fluorochromes, to characterize the distinctive spatial distributions and clearance times of circulating fluorochromes with different molecular sizes, and to produce unequivocal images of the heretofore uncharacterized mouse choroidal vasculature. PMID:26677070

Retrieval Algorithms for Road Surface Modelling Using Laser-Based Mobile Mapping.

PubMed

Jaakkola, Anttoni; Hyyppä, Juha; Hyyppä, Hannu; Kukko, Antero

2008-09-01

Automated processing of the data provided by a laser-based mobile mapping system will be a necessity due to the huge amount of data produced. In the future, vehiclebased laser scanning, here called mobile mapping, should see considerable use for road environment modelling. Since the geometry of the scanning and point density is different from airborne laser scanning, new algorithms are needed for information extraction. In this paper, we propose automatic methods for classifying the road marking and kerbstone points and modelling the road surface as a triangulated irregular network. On the basis of experimental tests, the mean classification accuracies obtained using automatic method for lines, zebra crossings and kerbstones were 80.6%, 92.3% and 79.7%, respectively.

R-on-1 automatic mapping: A new tool for laser damage testing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hue, J.; Garrec, P.; Dijon, J.

1996-12-31

Laser damage threshold measurement is statistical in nature. For a commercial qualification or for a user, the threshold determined by the weakest point is a satisfactory characterization. When a new coating is designed, threshold mapping is very useful. It enables the technology to be improved and followed more accurately. Different statistical parameters such as the minimum, maximum, average, and standard deviation of the damage threshold as well as spatial parameters such as the threshold uniformity of the coating can be determined. Therefore, in order to achieve a mapping, all the tested sites should give data. This is the major interestmore » of the R-on-1 test in spite of the fact that the laser damage threshold obtained by this method may be different from the 1-on-1 test (smaller or greater). Moreover, on the damage laser test facility, the beam size is smaller (diameters of a few hundred micrometers) than the characteristic sizes of the components in use (diameters of several centimeters up to one meter). Hence, a laser damage threshold mapping appears very interesting, especially for applications linked to large optical components like the Megajoule project or the National Ignition Facility (N.I.F). On the test bench used, damage detection with a Nomarski microscope and scattered light measurement are almost equivalent. Therefore, it becomes possible to automatically detect on line the first defects induced by YAG irradiation. Scattered light mappings and laser damage threshold mappings can therefore be achieved using a X-Y automatic stage (where the test sample is located). The major difficulties due to the automatic capabilities are shown. These characterizations are illustrated at 355 nm. The numerous experiments performed show different kinds of scattering curves, which are discussed in relation with the damage mechanisms.« less

Tip-leakage cavitation in the clearance of a 2D hydrofoil with fillets: high-speed visualization and PIV/PTV measurements

NASA Astrophysics Data System (ADS)

Zapryagaev, Ivan I.; Timoshevskiy, Mikhail V.; Pervunin, Konstantin S.

2017-09-01

Tip-clearance cavitation is one of the most aggressive forms of cavitation as it can cause surface erosion of hydraulic machinery elements and, as a result, their fatigue damage and disturb designed operating conditions. At present, the literature lacks for detailed experimental data on the inception and development of this type of cavitation at various flow conditions. In the paper, a tip-leakage cavitation occurring in the clearance between an end face of a 2D hydrofoil (a scaled-down model of guide vanes (GV) of a Francis turbine) and a transparent wall of the test section was studied. The experiments were carried out for different cavitating regimes on the cavitation number and two attack angles of 3° and 9°, with the gap size (tip clearance width) varied in the range from 0.4 to 0.8 mm. In order to determine the cavitation inception conditions and investigate the dynamics of the tip-leakage cavitation, a high-speed visualization was applied. A modified PIV/PTV technique with a diverging laser beam instead of a laser light sheet was used to measure the mean velocity distributions within the gap. It was shown that the cavitation pattern on the suction side of the GV model impacts the dynamics of the leakage flow in the gap but does not affect the sheet cavity formed close to the foil leading edge in the clearance as well as its size and dynamics. When the gap size is increased, the tip-leakage cavitation initiates at higher cavitation numbers or, in other words, conditions for the cavitation occurrence become more favorable.

Precision CW laser automatic tracking system investigated

NASA Technical Reports Server (NTRS)

Lang, K. T.; Lucy, R. F.; Mcgann, E. J.; Peters, C. J.

1966-01-01

Precision laser tracker capable of tracking a low acceleration target to an accuracy of about 20 microradians rms is being constructed and tested. This laser tracking has the advantage of discriminating against other optical sources and the capability of simultaneously measuring range.

Treatment of facial telangiectasias with a diode-pumped Nd:YAG laser at 532 nm.

PubMed

Cassuto, D A; Ancona, D M; Emanuelli, G

2000-09-01

Facial telangiectasias are a common cause of cosmetic concern. Current treatment modalities present various untoward effects and limits. The pulsed dye laser has been considered the gold standard in efficacy and safety; unfortunately it causes postoperative intracutaneous hematomata, discouraging many patients from undergoing this treatment. Several other vascular lasers (argon, tunable dye, copper, krypton, etc.) are disadvantaged by the risk of hypopigmented and atrophic scars. We assessed a recent powerful version of the potassium titanyl phosphate (KTP) 532 nm laser, which delivers sufficient energy in single pulse lasting 10-50 msec (DioLite 532; IRIDEX, Mountain View, CA, USA). Collateral damage is reduced while the heating of the vessel is slow enough to avoid explosive photothermolysis with its associated purpura. Sixty six patients with facial telangiectasias were treated. In 62/66 patients (93.9%) we achieved a 75-100% clearance of the lesions, while two treatments were needed to reach an acceptable clearance in the remaining 4/66 patients (6.1%). The eventual need for more sessions was well tolerated because the acceptable postoperative appearance allowed patients to continue normal business and social activities between treatments. No permanent complications or undesired effects were noted. We conclude that this diode-pumped frequency-doubled Nd:YAG laser is an effective device for the treatment of facial telangiectasias, with a low profile of undesired effects that can be well tolerated by patients.

Interstitial fluid drainage is impaired in ischemic stroke and Alzheimer’s disease mouse models

PubMed Central

Arbel-Ornath, Michal; Hudry, Eloise; Eikermann-Haerter, Katharina; Hou, Steven; Gregory, Julia L.; Zhao, Lingzhi; Betensky, Rebecca A.; Frosch, Matthew P.; Greenberg, Steven M.; Bacskai, Brian J.

2013-01-01

The interstitial fluid (ISF) drainage pathway has been hypothesized to underlie the clearance of solutes and metabolites from the brain. Previous work has implicated the perivascular spaces along arteries as the likely route for ISF clearance, however it has never been demonstrated directly. The accumulation of amyloid β (Aβ) peptides in brain parenchyma is one of the pathological hallmarks of Alzheimer disease (AD), and it is likely related to an imbalance between production and clearance of the peptide. Aβ drainage along perivascular spaces has been postulated to be one of the mechanisms that mediates the peptide clearance from the brain. We therefore devised a novel method to visualize solute clearance in real time in the living mouse brain using laser guided bolus dye injections and multiphoton imaging. This methodology allows high spatial and temporal resolution and revealed the kinetics of ISF clearance. We found that the ISF drains along perivascular spaces of arteries and capillaries but not veins, and its clearance exhibits a bi-exponential profile. ISF drainage requires a functional vasculature, as solute clearance decreased when perfusion was impaired. In addition, reduced solute clearance was observed in transgenic mice with significant vascular amyloid deposition; we suggest the existence of a feed-forward mechanism, by which amyloid deposition promotes further amyloid deposition. This important finding provides a mechanistic link between cerebrovascular disease and Alzheimer disease and suggests that facilitation of Aβ clearance along the perivascular pathway should be considered as a new target for therapeutic approaches to AD and CAA. PMID:23818064

Novel Treatment Approach for Deep Palmoplantar Warts Using Long-Pulsed 1064-nm Nd:YAG Laser and a Moisturizing Cream Without Prior Paring of the Wart Surface.

PubMed

Alshami, Mohammad Ali; Mohana, Mona Jameel

2016-10-01

The present study aimed to assess the safety and efficacy of palmoplantar wart removal using long-pulsed 1064-nm Nd:YAG laser after application of a moisturizing cream. Previously described laser treatments for wart removal are associated with negative side effects and need to pare the warts before laser treatment. Two hundred forty patients (142 males, 98 females) were treated for 1-40 palmoplantar warts by long-pulsed 1064-nm Nd:YAG laser (spot size 4-6 mm, pulse duration 20 msec, fluence 200 J/cm 2 ) after covering the wart surface with a thin film of a moisturizing cream. The endpoint was lesion graying or whitening with or without development of a hemorrhagic bulla beneath the treated wart. Color photographs were taken before and immediately after each laser session and at 1, 4, and 16 weeks after the last session. The overall clearance rate was 97%, with 90% of treated patients cured after one session, 4% after two, and 3% after three. Clearance rate after three laser sessions decreased linearly with the number of warts from 100% to 95%. Less accessible wart location in interdigital spaces also decreased the cure rate after three sessions from 100% to 95%. Additionally, warts became more difficult to eradicate as they aged. Remission lasted up to 6 years, and complications were mild and infrequent (17.5%). This novel method is effective in removing palmoplantar warts. It is easier, time-saving, and safer than other methods described in previous studies conducted with ablative or nonablative lasers.

Tetrahedral Hohlraum Visualization and Pointings

NASA Astrophysics Data System (ADS)

Klare, K. A.; Wallace, J. M.; Drake, D.

1997-11-01

In designing experiments for Omega, the tetrahedral hohlraum (a sphere with four holes) can make full use of all 60 beams. There are some complications: the beams must clear the laser entrance hole (LEH), must miss a central capsule, absolutely must not go out the other LEHs, and should distribute in the interior of the hohlraum to maximize the uniformity of irradiation on the capsule while keeping reasonable laser spot sizes. We created a 15-offset coordinate system with which an IDL program computes clearances, writes a file for QuickDraw 3D (QD3D) visualization, and writes input for the viewfactor code RAYNA IV. Visualizing and adjusting the parameters by eye gave more reliable results than computer optimization. QD3D images permitted quick live rotations to determine offsets. The clearances obtained insured safe operation and good physics. The viewfactor code computes the initial irradiation of the hohlraum and capsule or of a uniform hohlraum source with the loss through the four LEHs and shows a high degree of uniformity with both, better for lasers because this deposits more energy near the LEHs to compensate for the holes.

Automatic Rejection Of Multimode Laser Pulses

NASA Technical Reports Server (NTRS)

Tratt, David M.; Menzies, Robert T.; Esproles, Carlos

1991-01-01

Characteristic modulation detected, enabling rejection of multimode signals. Monitoring circuit senses multiple longitudinal mode oscillation of transversely excited, atmospheric-pressure (TEA) CO2 laser. Facility developed for inclusion into coherent detection laser radar (LIDAR) system. However, circuit described of use in any experiment where desireable to record data only when laser operates in single longitudinal mode.

An automatic system to study sperm motility and energetics

PubMed Central

Nascimento, Jaclyn M.; Chandsawangbhuwana, Charlie; Botvinick, Elliot L.; Berns, Michael W.

2012-01-01

An integrated robotic laser and microscope system has been developed to automatically analyze individual sperm motility and energetics. The custom-designed optical system directs near-infrared laser light into an inverted microscope to create a single-point 3-D gradient laser trap at the focal spot of the microscope objective. A two-level computer structure is described that quantifies the sperm motility (in terms of swimming speed and swimming force) and energetics (measuring mid-piece membrane potential) using real-time tracking (done by the upper-level system) and fluorescent ratio imaging (done by the lower-level system). The communication between these two systems is achieved by a gigabit network. The custom-built image processing algorithm identifies the sperm swimming trajectory in real-time using phase contrast images, and then subsequently traps the sperm by automatically moving the microscope stage to relocate the sperm to the laser trap focal plane. Once the sperm is stably trapped (determined by the algorithm), the algorithm can also gradually reduce the laser power by rotating the polarizer in the laser path to measure the trapping power at which the sperm is capable of escaping the trap. To monitor the membrane potential of the mitochondria located in a sperm’s mid-piece, the sperm is treated with a ratiometrically-encoded fluorescent probe. The proposed algorithm can relocate the sperm to the center of the ratio imaging camera and the average ratio value can be measured in real-time. The three parameters, sperm escape power, sperm swimming speed and ratio values of the mid-piece membrane potential of individual sperm can be compared with respect to time. This two-level automatic system to study individual sperm motility and energetics has not only increased experimental throughput by an order of magnitude but also has allowed us to monitor sperm energetics prior to and after exposure to the laser trap. This system should have application in both the human fertility clinic and in animal husbandry. PMID:18299996

An automatic system to study sperm motility and energetics.

PubMed

Shi, Linda Z; Nascimento, Jaclyn M; Chandsawangbhuwana, Charlie; Botvinick, Elliot L; Berns, Michael W

2008-08-01

An integrated robotic laser and microscope system has been developed to automatically analyze individual sperm motility and energetics. The custom-designed optical system directs near-infrared laser light into an inverted microscope to create a single-point 3-D gradient laser trap at the focal spot of the microscope objective. A two-level computer structure is described that quantifies the sperm motility (in terms of swimming speed and swimming force) and energetics (measuring mid-piece membrane potential) using real-time tracking (done by the upper-level system) and fluorescent ratio imaging (done by the lower-level system). The communication between these two systems is achieved by a gigabit network. The custom-built image processing algorithm identifies the sperm swimming trajectory in real-time using phase contrast images, and then subsequently traps the sperm by automatically moving the microscope stage to relocate the sperm to the laser trap focal plane. Once the sperm is stably trapped (determined by the algorithm), the algorithm can also gradually reduce the laser power by rotating the polarizer in the laser path to measure the trapping power at which the sperm is capable of escaping the trap. To monitor the membrane potential of the mitochondria located in a sperm's mid-piece, the sperm is treated with a ratiometrically-encoded fluorescent probe. The proposed algorithm can relocate the sperm to the center of the ratio imaging camera and the average ratio value can be measured in real-time. The three parameters, sperm escape power, sperm swimming speed and ratio values of the mid-piece membrane potential of individual sperm can be compared with respect to time. This two-level automatic system to study individual sperm motility and energetics has not only increased experimental throughput by an order of magnitude but also has allowed us to monitor sperm energetics prior to and after exposure to the laser trap. This system should have application in both the human fertility clinic and in animal husbandry.

Experimental and computational investigation of the tip clearance flow in a transonic axial compressor rotor

NASA Astrophysics Data System (ADS)

Suder, Kenneth L.; Celestina, Mark L.

1995-06-01

Experimental and computational techniques are used to investigate tip clearance flows in a transonic axial compressor rotor at design and part speed conditions. Laser anemometer data acquired in the endwall region are presented for operating conditions near peak efficiency and near stall at 100% design speed and at near peak efficiency at 60% design speed. The role of the passage shock/leakage vortex interaction in generating endwall blockage is discussed. As a result of the shock/vortex interaction at design speed, the radial influence of the tip clearance flow extends to 20 times the physical tip clearance height. At part speed, in the absence of the shock, the radial extent is only 5 times the tip clearance height. Both measurements and analysis indicate that under part-speed operating conditions a second vortex, which does not originate from the tip leakage flow, forms in the endwall region within the blade passage and exits the passage near midpitch. Mixing of the leakage vortex with primary flow downstream of the rotor at both design and part speed conditions is also discussed.

Experimental and Computational Investigation of the Tip Clearance Flow in a Transonic Axial Compressor Rotor

NASA Technical Reports Server (NTRS)

Suder, Kenneth L.; Celestina, Mark L.

1995-01-01

Experimental and computational techniques are used to investigate tip clearance flows in a transonic axial compressor rotor at design and part speed conditions. Laser anemometer data acquired in the endwall region are presented for operating conditions near peak efficiency and near stall at 100% design speed and at near peak efficiency at 60% design speed. The role of the passage shock/leakage vortex interaction in generating endwall blockage is discussed. As a result of the shock/vortex interaction at design speed, the radial influence of the tip clearance flow extends to 20 times the physical tip clearance height. At part speed, in the absence of the shock, the radial extent is only 5 times the tip clearance height. Both measurements and analysis indicate that under part-speed operating conditions a second vortex, which does not originate from the tip leakage flow, forms in the endwall region within the blade passage and exits the passage near midpitch. Mixing of the leakage vortex with primary flow downstream of the rotor at both design and part speed conditions is also discussed.

Automatic temperature controlled retinal photocoagulation

NASA Astrophysics Data System (ADS)

Schlott, Kerstin; Koinzer, Stefan; Ptaszynski, Lars; Bever, Marco; Baade, Alex; Roider, Johann; Birngruber, Reginald; Brinkmann, Ralf

2012-06-01

Laser coagulation is a treatment method for many retinal diseases. Due to variations in fundus pigmentation and light scattering inside the eye globe, different lesion strengths are often achieved. The aim of this work is to realize an automatic feedback algorithm to generate desired lesion strengths by controlling the retinal temperature increase with the irradiation time. Optoacoustics afford non-invasive retinal temperature monitoring during laser treatment. A 75 ns/523 nm Q-switched Nd:YLF laser was used to excite the temperature-dependent pressure amplitudes, which were detected at the cornea by an ultrasonic transducer embedded in a contact lens. A 532 nm continuous wave Nd:YAG laser served for photocoagulation. The ED50 temperatures, for which the probability of ophthalmoscopically visible lesions after one hour in vivo in rabbits was 50%, varied from 63°C for 20 ms to 49°C for 400 ms. Arrhenius parameters were extracted as ΔE=273 J mol-1 and A=3.1044 s-1. Control algorithms for mild and strong lesions were developed, which led to average lesion diameters of 162+/-34 μm and 189+/-34 μm, respectively. It could be demonstrated that the sizes of the automatically controlled lesions were widely independent of the treatment laser power and the retinal pigmentation.

CMO YAG laser damage test facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hue, J.; Dijon, J.; Lyan, P.

1996-12-31

The CMO YAG laser damage test facility, which is equipped with a 30Hz laser, is presented in this paper. The main points are described below: (1) The characteristics of the laser beam and the in situ damage detection technique (a scattered light measurement system) are perfectly suited to work up to the frequency of the laser. They are monitored in real time, and work at three wavelengths: 1064 nm, 532 nm, 355 nm. (2) With this same shutter, it is possible to automatically stop the laser on the pulse which induces the first damages. These automatic capabilities enable the samplesmore » to be tested quickly. (3) A Nomarski microscope supplied with a 16-bit CCD camera enables the test sites to be photographed before and after the laser interaction. Image processing enables the authors to extract the first damages. before and after the laser interaction. Image processing enables them to extract the first damages. (4) Six pulse widths are available (between 3ns and 13ns). Therefore, with all these characterization tools, many kinds of laser tests may be considered. These different features are illustrated by experimental results (1-on-1 test or R-on-1 test).« less

Response to Laser Treatment of Café au Lait Macules Based on Morphologic Features.

PubMed

Belkin, Daniel A; Neckman, Julia P; Jeon, Hana; Friedman, Paul; Geronemus, Roy G

2017-11-01

Response to laser treatment for café au lait macules (CALMs) is inconsistent and difficult to predict. To test the hypothesis that irregularly bordered CALMs of the "coast of Maine" subtype respond better to treatment than those of the smooth-bordered "coast of California" subtype. This retrospective case series included patients from 2 multiple-clinician US practices treated from 2005 through 2016. All patients had a clinical diagnosis of CALM and were treated with a Q-switched or picosecond laser. A total of 51 consecutive patients were eligible, 6 of whom were excluded owing to ambiguous lesion subtype. Observers were blinded to final patient groupings. Treatment with 755-nm alexandrite picosecond laser, Q-switched ruby laser, Q-switched alexandrite laser, or Q-switched 1064-nm Nd:YAG laser. Main outcome was grade in a visual analog scale (VAS) consisting of 4 levels of treatment response: poor (grade 1, 0%-25% improvement), fair (grade 2, 26%-50% improvement), good (grade 3, 51%-75% improvement), and excellent (grade 4, 76%-100% improvement). Forty-five patients were included in the series, 19 with smooth-bordered lesions and 26 with irregularly bordered lesions. Thirty-four (76%) of the participants were female; 33 (73%) were white; and the mean age at the time of laser treatment was 14.5 years (range, 0-44 years). Smooth-bordered lesions received a mean VAS score of 1.76, corresponding to a fair response on average (26%-50% pigmentary clearance). Irregularly bordered lesions received a mean VAS score of 3.67, corresponding to an excellent response on average (76%-100% clearance) (P < .001). CALMs with jagged or ill-defined borders of the coast of Maine subtype tend to respond well to laser treatment, whereas those with smooth and well-defined borders of the coast of California subtype tend to have poor response. Clinicians using Q-switched or picosecond lasers to treat CALMs can use morphologic characteristics to help predict response and more effectively manage patient expectations.

A novel integration of spectral-domain optical-coherence-tomography and laser-ablation system for precision treatment.

PubMed

Fan, Yingwei; Zhang, Boyu; Chang, Wei; Zhang, Xinran; Liao, Hongen

2018-03-01

Complete resection of diseased lesions reduces the recurrence of cancer, making it critical for surgical treatment. However, precisely resecting residual tumors is a challenge during operation. A novel integrated spectral-domain optical-coherence-tomography (SD-OCT) and laser-ablation therapy system for soft-biological-tissue resection is proposed. This is a prototype optical integrated diagnosis and therapeutic system as well as an optical theranostics system. We develop an optical theranostics system, which integrates SD-OCT, a laser-ablation unit, and an automatic scanning platform. The SD-OCT image of biological tissue provides an intuitive and clear view for intraoperative diagnosis and monitoring in real time. The effect of laser ablation is analyzed using a quantitative mathematical model. The automatic endoscopic scanning platform combines an endoscopic probe and an SD-OCT sample arm to provide optical theranostic scanning motion. An optical fiber and a charge-coupled device camera are integrated into the endoscopic probe, allowing detection and coupling of the OCT-aiming beam and laser spots. The integrated diagnostic and therapeutic system combines SD-OCT imaging and laser-ablation modules with an automatic scanning platform. OCT imaging, laser-ablation treatment, and the integration and control of diagnostic and therapeutic procedures were evaluated by performing phantom experiments. Furthermore, SD-OCT-guided laser ablation provided precision laser ablation and resection for the malignant lesions in soft-biological-tissue-lesion surgery. The results demonstrated that the appropriate laser-radiation power and duration time were 10 W and 10 s, respectively. In the laser-ablation evaluation experiment, the error reached approximately 0.1 mm. Another validation experiment was performed to obtain OCT images of the pre- and post-ablated craters of ex vivo porcine brainstem. We propose an optical integrated diagnosis and therapeutic system. The primary experimental results show the high efficiency and feasibility of our theranostics system, which is promising for realizing accurate resection of tumors in vivo and in situ in the future.

ND:YAG laser for preretinal hemorrhage in diabetic retinopathy.

PubMed

Karagiannis, Dimitrios; Kontadakis, Georgios A; Flanagan, Declan

2018-06-01

To present fundus images of a case with severe preretinal hemorrhage in diabetic retinopathy that was treated with posterior hyaloidotomy with an Nd:YAG laser. A 35-year-old diabetic patient presented with sudden painless loss of vision due to severe preretinal hemorrhage over the macular area and high risk proliferative diabetic retinopathy. Her visual acuity was counting fingers. Posterior hyaloid face was treated with Nd:YAG laser (posterior hyaloidotomy). Panretinal laser photocoagulation was first performed to control the proliferative diabetic retinopathy. Blood drained inferiorly into the vitreous cavity with clearance of the premacular area. Prompt treatment with Panretinal laser photocoagulation followed by posterior hyaloidotomy with the YAG laser is a viable option in order to avoid further proliferative diabetic retinopathy complications and vision loss. The current image clearly depicts treatment efficacy.

Automatic verification of SSD and generation of respiratory signal with lasers in radiotherapy: a preliminary study.

PubMed

Prabhakar, Ramachandran

2012-01-01

Source to surface distance (SSD) plays a very important role in external beam radiotherapy treatment verification. In this study, a simple technique has been developed to verify the SSD automatically with lasers. The study also suggests a methodology for determining the respiratory signal with lasers. Two lasers, red and green are mounted on the collimator head of a Clinac 2300 C/D linac along with a camera to determine the SSD. A software (SSDLas) was developed to estimate the SSD automatically from the images captured by a 12-megapixel camera. To determine the SSD to a patient surface, the external body contour of the central axis transverse computed tomography (CT) cut is imported into the software. Another important aspect in radiotherapy is the generation of respiratory signal. The changes in the lasers separation as the patient breathes are converted to produce a respiratory signal. Multiple frames of laser images were acquired from the camera mounted on the collimator head and each frame was analyzed with SSDLas to generate the respiratory signal. The SSD as observed with the ODI on the machine and SSD measured by the SSDlas software was found to be within the tolerance limit. The methodology described for generating the respiratory signals will be useful for the treatment of mobile tumors such as lung, liver, breast, pancreas etc. The technique described for determining the SSD and the generation of respiratory signals using lasers is cost effective and simple to implement. Copyright © 2011 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

An Automatic Procedure for Combining Digital Images and Laser Scanner Data

NASA Astrophysics Data System (ADS)

Moussa, W.; Abdel-Wahab, M.; Fritsch, D.

2012-07-01

Besides improving both the geometry and the visual quality of the model, the integration of close-range photogrammetry and terrestrial laser scanning techniques directs at filling gaps in laser scanner point clouds to avoid modeling errors, reconstructing more details in higher resolution and recovering simple structures with less geometric details. Thus, within this paper a flexible approach for the automatic combination of digital images and laser scanner data is presented. Our approach comprises two methods for data fusion. The first method starts by a marker-free registration of digital images based on a point-based environment model (PEM) of a scene which stores the 3D laser scanner point clouds associated with intensity and RGB values. The PEM allows the extraction of accurate control information for the direct computation of absolute camera orientations with redundant information by means of accurate space resection methods. In order to use the computed relations between the digital images and the laser scanner data, an extended Helmert (seven-parameter) transformation is introduced and its parameters are estimated. Precedent to that, in the second method, the local relative orientation parameters of the camera images are calculated by means of an optimized Structure and Motion (SaM) reconstruction method. Then, using the determined transformation parameters results in having absolute oriented images in relation to the laser scanner data. With the resulting absolute orientations we have employed robust dense image reconstruction algorithms to create oriented dense image point clouds, which are automatically combined with the laser scanner data to form a complete detailed representation of a scene. Examples of different data sets are shown and experimental results demonstrate the effectiveness of the presented procedures.

Laser Altimeter for Flight Simulator

NASA Technical Reports Server (NTRS)

Webster, L. D.

1986-01-01

Height of flight-simulator probe above model of terrain measured by automatic laser triangulation system. Airplane simulated by probe that moves over model of terrain. Altitude of airplane scaled from height of probe above model. Height measured by triangulation of laser beam aimed at intersection of model surface with plumb line of probe.

Design concepts using ring lasers for frequency stabilization

NASA Technical Reports Server (NTRS)

Mocker, H.

1967-01-01

Laser frequency stabilization methods are based on a frequency discriminant which generates an unambiguous deviation signal used for automatic stabilization. Closed-loop control stabilizes cavity length at a null point. Some systems have a stabilized ring laser using a piezoelectric dither and others use a Doppler gain tube.

Diode-pumped DUV cw all-solid-state laser to replace argon ion lasers

NASA Astrophysics Data System (ADS)

Zanger, Ekhard; Liu, B.; Gries, Wolfgang

2000-04-01

The slim series DELTATRAINTM-worldwide the first integrated cw diode-pumped all-solid-state DUV laser at 266 nm with a compact, slim design-has been developed. The slim design minimizes the DUV DPSSL footprint and thus greatly facilitates the replacement of commonly used gas ion lasers, including these with intra-cavity frequency doubling, in numerous industrial and scientific applications. Such a replacement will result in an operation cost reduction by several thousands US$DLR each year for one unit. Owing to its unique geometry-invariant frequency doubling cavity- based on the LAS patent-pending DeltaConcept architecture- this DUV laser provides excellent beam-pointing stability of <2 (mu) rad/ degree(s)C and power stability of <2%. The newest design of the cavity block has adopted a cemented resonator with each component positioned precisely inside a compact monolithic metal block. The automatic and precise crystal shifter ensures long operation lifetime of > 5000 hours of whole 266 nm laser. The microprocessor controlled power supply provides an automatic control of the whole 266 nm laser, making this DUV laser a hands-off system which can meet tough requirements posed by numerous industrial and scientific applications. It will replace the commonplace ion laser as the future DUV laser of choice.

Intelligent Image Analysis for Image-Guided Laser Hair Removal and Skin Therapy

NASA Technical Reports Server (NTRS)

Walker, Brian; Lu, Thomas; Chao, Tien-Hsin

2012-01-01

We present the development of advanced automatic target recognition (ATR) algorithms for the hair follicles identification in digital skin images to accurately direct the laser beam to remove the hair. The ATR system first performs a wavelet filtering to enhance the contrast of the hair features in the image. The system then extracts the unique features of the targets and sends the features to an Adaboost based classifier for training and recognition operations. The ATR system automatically classifies the hair, moles, or other skin lesion and provides the accurate coordinates of the intended hair follicle locations. The coordinates can be used to guide a scanning laser to focus energy only on the hair follicles. The intended benefit would be to protect the skin from unwanted laser exposure and to provide more effective skin therapy.

Treatment of ureteric calculi--use of Holmium: YAG laser lithotripsy versus pneumatic lithoclast.

PubMed

Tipu, Salman Ahmed; Malik, Hammad Afzal; Mohhayuddin, Nazim; Sultan, Gauhar; Hussain, Manzoor; Hashmi, Altaf; Naqvi, Syed Ali Anwar; Rizvi, Syed Adibul Hasan

2007-09-01

To compare the efficacy of Holmium: YAG laser and pneumatic lithoclast in treating ureteric calculi. The study included total of 100 patients divided into two equal groups of laser lithotripsy (LL) and pneumatic lithoclast (PL). Study was conducted between September 2006 and February 2007. Inclusion criteria were patients with a ureteric stone of size 1-2 cm and negative urine culture. An x-ray KUB was mandatory. IVU and CT pyelogram were also done when required. Procedures were done under general anaesthesia after a single dose of pre-operative antibiotic. A 7.5 Fr semi rigid ureteroscope was used for ureteroscopy in all cases. Holmium: YAG laser with 365 microm wide probe was employed in laser group and frequency was set between 5 and 10 Hz at a power of 10 to 15 W. Swiss lithoclast with single or multiple fire technique was used accordingly in PL group. Postoperatively patients underwent radiography and helical CT as required at 4th week of follow up to asses stone clearance. The mean patient age in LL and PL group was 38 +/- 10 and 40 +/- 10 years respectively. The male to female ratio and stone size were similar between the groups. Stone migration up in pelvicalyceal system occurred in two patients of LL group while in eight patients of PL group. JJ Stent was placed in 5(10%) patients in laser group where as 13 (26%) patients required it in pneumatic lithoclast group. Stone free rate at 4 weeks was 92% in laser group as compared to 82% in pneumatic lithoclast group. Hospital stay was more than 24 hours in 2 patients of laser group as compared to 5 patients of pneumatic lithoclast group. Complication rate was 4% in LL group whereas it was 14% in PL group. Holmium: YAG laser lithotripsy is a superior technology compared to pneumatic lithoclast in terms of rate of stone clearance and complications, especially in upper ureteric stones.

Laser Balancing

NASA Technical Reports Server (NTRS)

1981-01-01

Mechanical Technology, Incorporated developed a fully automatic laser machining process that allows more precise balancing removes metal faster, eliminates excess metal removal and other operator induced inaccuracies, and provides significant reduction in balancing time. Manufacturing costs are reduced as a result.

Recent advances in automatic alignment system for the National Ignition Facility

NASA Astrophysics Data System (ADS)

Wilhelmsen, Karl; Awwal, Abdul A. S.; Kalantar, Dan; Leach, Richard; Lowe-Webb, Roger; McGuigan, David; Miller Kamm, Vicki

2011-03-01

The automatic alignment system for the National Ignition Facility (NIF) is a large-scale parallel system that directs all 192 laser beams along the 300-m optical path to a 50-micron focus at target chamber in less than 50 minutes. The system automatically commands 9,000 stepping motors to adjust mirrors and other optics based upon images acquired from high-resolution digital cameras viewing beams at various locations. Forty-five control loops per beamline request image processing services running on a LINUX cluster to analyze these images of the beams and references, and automatically steer the beams toward the target. This paper discusses the upgrades to the NIF automatic alignment system to handle new alignment needs and evolving requirements as related to various types of experiments performed. As NIF becomes a continuously-operated system and more experiments are performed, performance monitoring is increasingly important for maintenance and commissioning work. Data, collected during operations, is analyzed for tuning of the laser and targeting maintenance work. Handling evolving alignment and maintenance needs is expected for the planned 30-year operational life of NIF.

Note: Digital laser frequency auto-locking for inter-satellite laser ranging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luo, Yingxin; Yeh, Hsien-Chi, E-mail: yexianji@mail.hust.edu.cn; Li, Hongyin

2016-05-15

We present a prototype of a laser frequency auto-locking and re-locking control system designed for laser frequency stabilization in inter-satellite laser ranging system. The controller has been implemented on field programmable gate arrays and programmed with LabVIEW software. The controller allows initial frequency calibrating and lock-in of a free-running laser to a Fabry-Pérot cavity. Since it allows automatic recovery from unlocked conditions, benefit derives to automated in-orbit operations. Program design and experimental results are demonstrated.

Automatic laser beam alignment using blob detection for an environment monitoring spectroscopy

NASA Astrophysics Data System (ADS)

Khidir, Jarjees; Chen, Youhua; Anderson, Gary

2013-05-01

This paper describes a fully automated system to align an infra-red laser beam with a small retro-reflector over a wide range of distances. The component development and test were especially used for an open-path spectrometer gas detection system. Using blob detection under OpenCV library, an automatic alignment algorithm was designed to achieve fast and accurate target detection in a complex background environment. Test results are presented to show that the proposed algorithm has been successfully applied to various target distances and environment conditions.

System for beaming power from earth to a high altitude platform

DOEpatents

Friedman, Herbert W.; Porter, Terry J.

2002-01-01

Power is transmitted to a high altitude platform by an array of diode pumped solid state lasers each operated at a single range of laser wavelengths outside of infrared and without using adaptive optics. Each laser produces a beam with a desired arrival spot size. An aircraft avoidance system uses a radar system for automatic control of the shutters of the lasers.

Optimization of technological equipment used in the laser-radiation hardening of instruments

NASA Astrophysics Data System (ADS)

Tverdokhlebov, G. N.; Maznichenko, S. A.

Results of a statistical analysis of an instrument intended for laser hardening are presented. The kinematics of the positioning and fastening of an instrument for uniform laser-pulse treatment is analyzed. The results are used to devise an automatic device and the procedure for laser treatment under optimized conditions of various rotary cutting instruments, such as milling cutters, drills, and counterbores.

Detecting asphalt pavement raveling using emerging 3D laser technology and macrotexture analysis.

DOT National Transportation Integrated Search

2015-08-01

This research project comprehensively tested and validated the automatic raveling detection, classification, : and measurement algorithms using 3D laser technology that were developed through a project sponsored by : the National Cooperative Highway ...

An automatic robotic system for three-dimensional tooth crown preparation using a picosecond laser.

PubMed

Wang, Lei; Wang, Dangxiao; Zhang, Yuru; Ma, Lei; Sun, Yuchun; Lv, Peijun

2014-09-01

Laser techniques have been introduced into dentistry to overcome the drawbacks of traditional treatment methods. The existing methods in dental clinical operations for tooth crown preparation have several drawbacks which affect the long-term success of the dental treatment. To develop an improved robotic system to manipulate the laser beam to achieve safe and accurate three-dimensional (3D) tooth ablation, and thus to realize automatic tooth crown preparation in clinical operations. We present an automatic laser ablation system for tooth crown preparation in dental restorative operations. The system, combining robotics and laser technology, is developed to control the laser focus in three-dimensional motion aiming for high speed and accuracy crown preparation. The system consists of an end-effector, a real-time monitor and a tooth fixture. A layer-by-layer ablation method is developed to control the laser focus during the crown preparation. Experiments are carried out with picosecond laser on wax resin and teeth. The accuracy of the system is satisfying, achieving the average linear errors of 0.06 mm for wax resin and 0.05 mm for dentin. The angle errors are 4.33° for wax resin and 0.5° for dentin. The depth errors for wax resin and dentin are both within 0.1 mm. The ablation time is 1.5 hours for wax resin and 3.5 hours for dentin. The ablation experimental results show that the movement range and the resolution of the robotic system can meet the requirements of typical dental operations for tooth crown preparation. Also, the errors of tooth shape and preparation angle are able to satisfy the requirements of clinical crown preparation. Although the experimental results illustrate the potential of using picosecond lasers for 3D tooth crown preparation, many research issues still need to be studied before the system can be applied to clinical operations. © 2014 Wiley Periodicals, Inc.

Automatic Train Operation Using Autonomic Prediction of Train Runs

NASA Astrophysics Data System (ADS)

Asuka, Masashi; Kataoka, Kenji; Komaya, Kiyotoshi; Nishida, Syogo

In this paper, we present an automatic train control method adaptable to disturbed train traffic conditions. The proposed method presumes transmission of detected time of a home track clearance to trains approaching to the station by employing equipment of Digital ATC (Automatic Train Control). Using the information, each train controls its acceleration by the method that consists of two approaches. First, by setting a designated restricted speed, the train controls its running time to arrive at the next station in accordance with predicted delay. Second, the train predicts the time at which it will reach the current braking pattern generated by Digital ATC, along with the time when the braking pattern transits ahead. By comparing them, the train correctly chooses the coasting drive mode in advance to avoid deceleration due to the current braking pattern. We evaluated the effectiveness of the proposed method regarding driving conditions, energy consumption and reduction of delays by simulation.

Long-term clinical evaluation of a 800-nm long-pulsed diode laser with a large spot size and vacuum-assisted suction for hair removal.

PubMed

Ibrahimi, Omar A; Kilmer, Suzanne L

2012-06-01

The long-pulsed diode (800-810-nm) laser is one of the most commonly used and effective lasers for hair removal. Limitations of currently available devices include a small treatment spot size, treatment-associated pain, and the need for skin cooling. To evaluate the long-term hair reduction capabilities of a long-pulsed diode laser with a large spot size and vacuum assisted suction. Thirty-five subjects were enrolled in a prospective, self-controlled, single-center study of axillary hair removal. The study consisted of three treatments using a long-pulsed diode laser with a large spot size and vacuum-assisted suction at 4- to 6-week intervals with follow-up visits 6 and 15 months after the last treatment. Hair clearance was quantified using macro hair-count photographs taken at baseline and at 6- and 15-month follow-up visits. Changes in hair thickness and color, levels of treatment-associated pain, and adverse events were additional study endpoints. There was statistically significant hair clearance at the 6 (54%) and 15-month (42%) follow-up visits. Remaining hairs were thinner and lighter at the 15-month follow-up visit, and the majority of subjects reported feeling up to mild to moderate pain during treatment without the use of pretreatment anesthesia or skin cooling. A long-pulsed diode laser with a large spot size and vacuum-assisted suction is safe and effective for long-term hair removal. This is the largest prospective study to evaluate long-term hair removal and the first to quantify decreases in hair thickness and darkness with treatment. © 2012 by the American Society for Dermatologic Surgery, Inc. Published by Wiley Periodicals, Inc.

Development of the micro-scanning optical system of yellow laser applied to the ophthalmologic area

NASA Astrophysics Data System (ADS)

Ortega, Tiago A.; Mota, Alessandro D.; Costal, Glauco Z.; Fontes, Yuri C.; Rossi, Giuliano; Yasuoka, Fatima M. M.; Stefani, Mario A.; de Castro N., Jarbas C.

2012-10-01

In this work, the development of a laser scanning system for ophthalmology with micrometric positioning precision is presented. It is a semi-automatic scanning system for retina photocoagulation and laser trabeculoplasty. The equipment is a solid state laser fully integrated to the slit lamp. An optical system is responsible for producing different laser spot sizes on the image plane and a pair of galvanometer mirrors generates the scanning patterns.

Automatic Locking of Laser Frequency to an Absorption Peak

NASA Technical Reports Server (NTRS)

Koch, Grady J.

2006-01-01

An electronic system adjusts the frequency of a tunable laser, eventually locking the frequency to a peak in the optical absorption spectrum of a gas (or of a Fabry-Perot cavity that has an absorption peak like that of a gas). This system was developed to enable precise locking of the frequency of a laser used in differential absorption LIDAR measurements of trace atmospheric gases. This system also has great commercial potential as a prototype of means for precise control of frequencies of lasers in future dense wavelength-division-multiplexing optical communications systems. The operation of this system is completely automatic: Unlike in the operation of some prior laser-frequency-locking systems, there is ordinarily no need for a human operator to adjust the frequency manually to an initial value close enough to the peak to enable automatic locking to take over. Instead, this system also automatically performs the initial adjustment. The system (see Figure 1) is based on a concept of (1) initially modulating the laser frequency to sweep it through a spectral range that includes the desired absorption peak, (2) determining the derivative of the absorption peak with respect to the laser frequency for use as an error signal, (3) identifying the desired frequency [at the very top (which is also the middle) of the peak] as the frequency where the derivative goes to zero, and (4) thereafter keeping the frequency within a locking range and adjusting the frequency as needed to keep the derivative (the error signal) as close as possible to zero. More specifically, the system utilizes the fact that in addition to a zero crossing at the top of the absorption peak, the error signal also closely approximates a straight line in the vicinity of the zero crossing (see Figure 2). This vicinity is the locking range because the linearity of the error signal in this range makes it useful as a source of feedback for a proportional + integral + derivative control scheme that constantly adjusts the frequency in an effort to drive the error to zero. When the laser frequency deviates from the midpeak value but remains within the locking range, the magnitude and sign of the error signal indicate the amount of detuning and the control circuitry adjusts the frequency by what it estimates to be the negative of this amount in an effort to bring the error to zero.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sels, Seppe, E-mail: Seppe.Sels@uantwerpen.be; Ribbens, Bart; Mertens, Luc

Scanning laser Doppler vibrometers (LDV) are used to measure full-field vibration shapes of products and structures. In most commercially available scanning laser Doppler vibrometer systems the user manually draws a grid of measurement locations on a 2D camera image of the product. The determination of the correct physical measurement locations can be a time consuming and diffcult task. In this paper we present a new methodology for product testing and quality control that integrates 3D imaging techniques with vibration measurements. This procedure allows to test prototypes in a shorter period because physical measurements locations will be located automatically. The proposedmore » methodology uses a 3D time-of-flight camera to measure the location and orientation of the test-object. The 3D image of the time-of-flight camera is then matched with the 3D-CAD model of the object in which measurement locations are pre-defined. A time of flight camera operates strictly in the near infrared spectrum. To improve the signal to noise ratio in the time-of-flight measurement, a time-of-flight camera uses a band filter. As a result of this filter, the laser spot of most laser vibrometers is invisible in the time-of-flight image. Therefore a 2D RGB-camera is used to find the laser-spot of the vibrometer. The laser spot is matched to the 3D image obtained by the time-of-flight camera. Next an automatic calibration procedure is used to aim the laser at the (pre)defined locations. Another benefit from this methodology is that it incorporates automatic mapping between a CAD model and the vibration measurements. This mapping can be used to visualize measurements directly on a 3D CAD model. Secondly the orientation of the CAD model is known with respect to the laser beam. This information can be used to find the direction of the measured vibration relatively to the surface of the object. With this direction, the vibration measurements can be compared more precisely with numerical experiments.« less

Qualitative Maintenance Experience Handbook. P-3C/S-3A Supplement.

DTIC Science & Technology

1977-06-15

axle which automatically assists in disc alignment, a positive feature, in easing maintenance and preventing casual damage. Brake assemblies should...Reverse Of Removal Use brake tool to align brake discs . After Installation Actions: _ Bleed _ Rig _ Adjust X Service Lubricate - Boresight. _ Other...Hydraulic I Access Required: Test Equipment Required: Actions: 1. Check clearance of discs after brakes are put on. 2. Apply brakes . 8 ANALYST’S COMMENTS

Laser therapy for periodontitis

NASA Astrophysics Data System (ADS)

Efanov, O. I.

2001-04-01

An investigation was made of applying pulsed (lambda) equals 0.89 micrometers laser radiation in the treatment for early diagnosed periodontitis. The investigation was made on 65 patients (47 patients constituted the experimental group and 18 patients constituted a control group) affected by periodontitis. Clinical and functional tests revealed that laser therapy produced a string effect on the course of the illness. It reduced bleeding, inflammation, and pruritus. However, it did not produce an affect on electroexcitation. Biomicroscopic examinations and periodontium rheography revealed that the gingival blood flow became normal after the course of laser therapy. The capillary permeability and venous congestion decreased, which was confirmed by the increased time of vacuum tests, raised gingival temperature, reduced tissue clearance, and increased oxygen tension. Apart from that, laser therapy subsided fibrinolysis, proteolytic tissue activity, and decreased the exudative inflammation of periodontium.

Treating vascular lesions.

PubMed

Astner, Susanne; Anderson, R Rox

2005-01-01

The treatment of acquired vascular lesions is one of the most commonly requested and performed cutaneous laser procedures. Furthermore, every year, 40,000 children are born in the United States each with congenital vascular lesions and malformations. Laser treatment of vascular lesion is based on the principle of selective photothermolysis, conceived in the 1980s. A variety of different lasers and light sources have since been used in the treatment of vascular lesions: lasers with wavelengths between green and yellow, near infrared lasers, and broadband light sources. Despite limitations, this remains the treatment of choice today. This publication addresses acquired and congenital vascular lesions as different entities and proposes a separation of vascular lesions into those that can easily be treated from those where clearance is difficult. Different treatment modalities and the various endpoints of individual vascular lesions will be discussed.

Software-aided automatic laser optoporation and transfection of cells

PubMed Central

Georg Breunig, Hans; Uchugonova, Aisada; Batista, Ana; König, Karsten

2015-01-01

Optoporation, the permeabilization of a cell membrane by laser pulses, has emerged as a powerful non-invasive and highly efficient technique to induce transfection of cells. However, the usual tedious manual targeting of individual cells significantly limits the addressable cell number. To overcome this limitation, we present an experimental setup with custom-made software control, for computer-automated cell optoporation. The software evaluates the image contrast of cell contours, automatically designates cell locations for laser illumination, centres those locations in the laser focus, and executes the illumination. By software-controlled meandering of the sample stage, in principle all cells in a typical cell culture dish can be targeted without further user interaction. The automation allows for a significant increase in the number of treatable cells compared to a manual approach. For a laser illumination duration of 100 ms, 7-8 positions on different cells can be targeted every second inside the area of the microscope field of view. The experimental capabilities of the setup are illustrated in experiments with Chinese hamster ovary cells. Furthermore, the influence of laser power is discussed, with mention on post-treatment cell survival and optoporation-efficiency rates. PMID:26053047

980 nm diode laser with automatic power control mode for dermatological applications

NASA Astrophysics Data System (ADS)

Belikov, Andrey V.; Gelfond, Mark L.; Shatilova, Ksenia V.; Sosenkova, Svetlana A.; Lazareva, Anastasia A.

2015-07-01

Results of nevus, papilloma, dermatofibroma, and basal cell skin cancer removal by a 980+/-10 nm diode laser with "blackened" tip operating in continuous (CW) mode and automatic power control (APC) mode are compared. It was demonstrated that using APC mode decreases the width of collateral damage at removing of these nosological neoplasms of human skin. The mean width of collateral damage reached 0.846+/-0.139 mm for patient group with nevus removing by 980 nm diode laser operating in CW mode, papilloma - 0.443+/-0.312 mm, dermatofibroma - 0.923+/-0.271 mm, and basal cell skin cancer - 0.787+/-0.325 mm. The mean width of collateral damage reached 0.592+/-0.197 mm for patient group with nevus removing by 980 nm diode laser operating in APC mode, papilloma - 0.191+/-0.162 mm, dermatofibroma - 0.476+/-0.366 mm, and basal cell skin cancer - 0.517+/-0.374 mm. It was found that the percentage of laser wounds with collateral damage less than 300 μm of quantity of removed nosological neoplasms in APC mode is 50%, that significantly higher than the percentage of laser wounds obtained using CW mode (13.4%).

New software tools for enhanced precision in robot-assisted laser phonomicrosurgery.

PubMed

Dagnino, Giulio; Mattos, Leonardo S; Caldwell, Darwin G

2012-01-01

This paper describes a new software package created to enhance precision during robot-assisted laser phonomicrosurgery procedures. The new software is composed of three tools for camera calibration, automatic tumor segmentation, and laser tracking. These were designed and developed to improve the outcome of this demanding microsurgical technique, and were tested herein to produce quantitative performance data. The experimental setup was based on the motorized laser micromanipulator created by Istituto Italiano di Tecnologia and the experimental protocols followed are fully described in this paper. The results show the new tools are robust and effective: The camera calibration tool reduced residual errors (RMSE) to 0.009 ± 0.002 mm under 40× microscope magnification; the automatic tumor segmentation tool resulted in deep lesion segmentations comparable to manual segmentations (RMSE= 0.160 ± 0.028 mm under 40× magnification); and the laser tracker tool proved to be reliable even during cutting procedures (RMSE= 0.073 ± 0.023 mm under 40× magnification). These results demonstrate the new software package can provide excellent improvements to the previous microsurgical system, leading to important enhancements in surgical outcome.

Development of a Novel System to Measure a Clearance of a Passenger Platform

NASA Astrophysics Data System (ADS)

Shimizu, M.; Oizumi, J.; Matsuoka, R.; Takeda, H.; Okukura, H.; Ooya, A.; Koike, A.

2016-06-01

Clearances of a passenger platform at a railway station should be appropriately maintained for safety of both trains and passengers. In most Japanese railways clearances between a platform and a train car is measured precisely once or twice a year. Because current measurement systems operate on a track, the closure of the track is unavoidable. Since the procedure of the closure of a track is time-consuming and bothersome, we decided to develop a new system to measure clearances without the closure of a track. A new system is required to work on a platform and the required measurement accuracy is less than several millimetres. We have adopted a 3D laser scanner and stop-and-go operation for a new system. The current systems on a track measure clearances continuously at walking speed, while our system on a platform measures clearances at approximately ten metres intervals. The scanner controlled by a PC acquires a set of point data at each measuring station. Edge points of the platform, top and side points of two rails are detected from the acquired point data. Finally clearances of the platform are calculated by using the detected feature points of the platform and the rails. The results of an experiment using a prototype of our system show that the measurement accuracy by our system would be satisfactory, but our system would take more time than the current systems. Since our system requires no closure of a track, we conclude that our system would be convenient and effective.

JT9D performance deterioration results from a simulated aerodynamic load test

NASA Technical Reports Server (NTRS)

Stakolich, E. G.; Stromberg, W. J.

1981-01-01

The results of testing to identify the effects of simulated aerodynamic flight loads on JT9D engine performance are presented. The test results were also used to refine previous analytical studies on the impact of aerodynamic flight loads on performance losses. To accomplish these objectives, a JT9D-7AH engine was assembled with average production clearances and new seals as well as extensive instrumentation to monitor engine performance, case temperatures, and blade tip clearance changes. A special loading device was designed and constructed to permit application of known moments and shear forces to the engine by the use of cables placed around the flight inlet. The test was conducted in the Pratt & Whitney Aircraft X-Ray Test Facility to permit the use of X-ray techniques in conjunction with laser blade tip proximity probes to monitor important engine clearance changes. Upon completion of the test program, the test engine was disassembled, and the condition of gas path parts and final clearances were documented. The test results indicate that the engine lost 1.1 percent in thrust specific fuel consumption (TSFC), as measured under sea level static conditions, due to increased operating clearances caused by simulated flight loads. This compares with 0.9 percent predicted by the analytical model and previous study efforts.

Recommendations for Achieving Accurate Numerical Simulation of Tip Clearance Flows in Transonic Compressor Rotors

NASA Technical Reports Server (NTRS)

VanZante, Dale E.; Strazisar, Anthony J.; Wood, Jerry R,; Hathaway, Michael D.; Okiishi, Theodore H.

2000-01-01

The tip clearance flows of transonic compressor rotors are important because they have a significant impact on rotor and stage performance. While numerical simulations of these flows are quite sophisticated. they are seldom verified through rigorous comparisons of numerical and measured data because these kinds of measurements are rare in the detail necessary to be useful in high-speed machines. In this paper we compare measured tip clearance flow details (e.g. trajectory and radial extent) with corresponding data obtained from a numerical simulation. Recommendations for achieving accurate numerical simulation of tip clearance flows are presented based on this comparison. Laser Doppler Velocimeter (LDV) measurements acquired in a transonic compressor rotor, NASA Rotor 35, are used. The tip clearance flow field of this transonic rotor was simulated using a Navier-Stokes turbomachinery solver that incorporates an advanced k-epsilon turbulence model derived for flows that are not in local equilibrium. Comparison between measured and simulated results indicates that simulation accuracy is primarily dependent upon the ability of the numerical code to resolve important details of a wall-bounded shear layer formed by the relative motion between the over-tip leakage flow and the shroud wall. A simple method is presented for determining the strength of this shear layer.

76 FR 36169 - Agency Information Collection Activities: Requests for Comments; Clearance of Renewed Approval of...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-21

.... The requested reporting involves an immediate broadcast notification to Air Traffic Control (ATC) when... INFORMATION: OMB Control Number: 2120-0698. Title: Reporting of Laser Illumination of Aircraft. Form Numbers: Advisory Circular 70-2. Type of Review: Renewal of an information collection. Background: Advisory Circular...

Automatic Suppression of Intense Monochromatic Light in Electro-Optical Sensors

PubMed Central

Ritt, Gunnar; Eberle, Bernd

2012-01-01

Electro-optical imaging sensors are widely distributed and used for many different tasks. Due to technical improvements, their pixel size has been steadily decreasing, resulting in a reduced saturation capacity. As a consequence, this progress makes them susceptible to intense point light sources. Developments in laser technology have led to very compact and powerful laser sources of any wavelength in the visible and near infrared spectral region, offered as laser pointers. The manifold of wavelengths makes it difficult to encounter sensor saturation over the complete operating waveband by conventional measures like absorption or interference filters. We present a concept for electro-optical sensors to suppress overexposure in the visible spectral region. The key element of the concept is a spatial light modulator in combination with wavelength multiplexing. This approach allows spectral filtering within a localized area in the field of view of the sensor. The system offers the possibility of automatic reduction of overexposure by monochromatic laser radiation. PMID:23202039

Extrinsic Calibration of a Laser Galvanometric Setup and a Range Camera.

PubMed

Sels, Seppe; Bogaerts, Boris; Vanlanduit, Steve; Penne, Rudi

2018-05-08

Currently, galvanometric scanning systems (like the one used in a scanning laser Doppler vibrometer) rely on a planar calibration procedure between a two-dimensional (2D) camera and the laser galvanometric scanning system to automatically aim a laser beam at a particular point on an object. In the case of nonplanar or moving objects, this calibration is not sufficiently accurate anymore. In this work, a three-dimensional (3D) calibration procedure that uses a 3D range sensor is proposed. The 3D calibration is valid for all types of objects and retains its accuracy when objects are moved between subsequent measurement campaigns. The proposed 3D calibration uses a Non-Perspective-n-Point (NPnP) problem solution. The 3D range sensor is used to calculate the position of the object under test relative to the laser galvanometric system. With this extrinsic calibration, the laser galvanometric scanning system can automatically aim a laser beam to this object. In experiments, the mean accuracy of aiming the laser beam on an object is below 10 mm for 95% of the measurements. This achieved accuracy is mainly determined by the accuracy and resolution of the 3D range sensor. The new calibration method is significantly better than the original 2D calibration method, which in our setup achieves errors below 68 mm for 95% of the measurements.

Automatic Method for Building Indoor Boundary Models from Dense Point Clouds Collected by Laser Scanners

PubMed Central

Valero, Enrique; Adán, Antonio; Cerrada, Carlos

2012-01-01

In this paper we present a method that automatically yields Boundary Representation Models (B-rep) for indoors after processing dense point clouds collected by laser scanners from key locations through an existing facility. Our objective is particularly focused on providing single models which contain the shape, location and relationship of primitive structural elements of inhabited scenarios such as walls, ceilings and floors. We propose a discretization of the space in order to accurately segment the 3D data and generate complete B-rep models of indoors in which faces, edges and vertices are coherently connected. The approach has been tested in real scenarios with data coming from laser scanners yielding promising results. We have deeply evaluated the results by analyzing how reliably these elements can be detected and how accurately they are modeled. PMID:23443369

A novel dual‐wavelength, Nd:YAG, picosecond‐domain laser safely and effectively removes multicolor tattoos

PubMed Central

Schomacker, Kevin T.; Basilavecchio, Lisa D.; Plugis, Jessica M.; Bhawalkar, Jayant D.

2015-01-01

Background and Objectives Although nanosecond‐domain lasers have been the mainstay of laser tattoo removal for decades, recent disruptive innovations in laser design have introduced a new class of commercial Q‐switched lasers that generate picosecond‐domain pulses. Study A picosecond‐domain, Nd:YAG laser with a KTP frequency‐doubling crystal was used to treat 31 decorative tattoos in 21 subjects. Safety and effectiveness were determined by blinded evaluation of digital images in this prospective clinical study. Results The average clearance overall as evaluated by blinded observers evaluating randomized digital photographs was 79 ± 0.9% (mean ± sem) after an average of 6.5 treatments. Of the 31 tattoos completing treatment, 6 had evidence of mild hyper‐ or hypo‐pigmentation by evaluation of photographs. Conclusion The 350 picosecond, 532 nm, and 450 picosecond 1,064 nm Nd:YAG laser is safe and effective for removing decorative tattoos. Lasers Surg. Med. 47:542–548, 2015. © 2015 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc. PMID:26175187

A split face study to document the safety and efficacy of clearance of melasma with a 5 ns q switched Nd YAG laser versus a 50 ns q switched Nd YAG laser.

PubMed

Alsaad, Salman M S; Ross, E Victor; Mishra, Vineet; Miller, Lee

2014-12-01

To determine the safety and efficacy of a 50 ns Q switched Nd YAG laser vs. a 5 ns Q switched Nd YAG laser for clearance of melasma. To compare subject satisfaction, efficacy, and comfort level between the two lasers. This is a prospective, randomized split face clinical study. The study was approved by the Scripps IRB. Ten healthy female subjects with moderate to severe melasma were enrolled. Each subject had three laser treatments one month apart. Patients were followed up approximately 1 month, 3 months, and 6 months after the final laser treatment. A treatment session consisted of a microdermabrasion, 1064 nm QS laser, and topicals. Subjects were asked to rate treatment pain based on a numerical scale range 0-10 (0 = no pain and 10 = worst pain). A melasma area and severity index (MASI) grading system was applied. Also, melanin measurements were acquired by a reflectance spectrophotometer. Side effects were documented during the study including post treatment erythema. Eight patients completed the study. Subjects showed improvement on both sides of the face. From baseline to 1 month post the final laser treatment, the average MASI scores showed a 16% reduction for the 50 ns QS 1064 nm laser vs. a 27% reduction for the 5 ns QS 1064 nm laser (both significant versus baseline pigment, P < 0.05). This difference in MASI scores between the two lasers was not statistically significant (P = 0.87930). Laser treatments displayed mild erythema that resolved after one day. The melanin meter measurements showed a reduction in pigment readings on both sides. Three months after the final treatment there was some relapse in the melasma, as the mean pigment reduction fell to 12% for the 50 ns laser and 11% for the 5 ns laser. By 3 months pigment reduction was not statistically significant for either laser, and no significant differences in pigment reduction were noted between the two pulse durations. There was a statistically significant difference (P < 0.05) in pain scores reported by the subjects (scale 0-10), the mean pain score for 50 ns QS 1064 nm laser was 1.2 and for the 5 ns QS 2.9 the score was 2.9. In this study, we showed that a combination of microdermabrasion, QS1064 nm laser, and topicals decreased the MASI and meter scores without clinically significant side effects. Moreover, the longer pulsed Q switched 1064 nm laser i.e. (50 ns) was associated with less pain than its shorter pulse width counterpart. © 2014 Wiley Periodicals, Inc.

A dual growing method for the automatic extraction of individual trees from mobile laser scanning data

NASA Astrophysics Data System (ADS)

Li, Lin; Li, Dalin; Zhu, Haihong; Li, You

2016-10-01

Street trees interlaced with other objects in cluttered point clouds of urban scenes inhibit the automatic extraction of individual trees. This paper proposes a method for the automatic extraction of individual trees from mobile laser scanning data, according to the general constitution of trees. Two components of each individual tree - a trunk and a crown can be extracted by the dual growing method. This method consists of coarse classification, through which most of artifacts are removed; the automatic selection of appropriate seeds for individual trees, by which the common manual initial setting is avoided; a dual growing process that separates one tree from others by circumscribing a trunk in an adaptive growing radius and segmenting a crown in constrained growing regions; and a refining process that draws a singular trunk from the interlaced other objects. The method is verified by two datasets with over 98% completeness and over 96% correctness. The low mean absolute percentage errors in capturing the morphological parameters of individual trees indicate that this method can output individual trees with high precision.

Grammar-based Automatic 3D Model Reconstruction from Terrestrial Laser Scanning Data

NASA Astrophysics Data System (ADS)

Yu, Q.; Helmholz, P.; Belton, D.; West, G.

2014-04-01

The automatic reconstruction of 3D buildings has been an important research topic during the last years. In this paper, a novel method is proposed to automatically reconstruct the 3D building models from segmented data based on pre-defined formal grammar and rules. Such segmented data can be extracted e.g. from terrestrial or mobile laser scanning devices. Two steps are considered in detail. The first step is to transform the segmented data into 3D shapes, for instance using the DXF (Drawing Exchange Format) format which is a CAD data file format used for data interchange between AutoCAD and other program. Second, we develop a formal grammar to describe the building model structure and integrate the pre-defined grammars into the reconstruction process. Depending on the different segmented data, the selected grammar and rules are applied to drive the reconstruction process in an automatic manner. Compared with other existing approaches, our proposed method allows the model reconstruction directly from 3D shapes and takes the whole building into account.

Treatment of psoriasis and long-term maintenance using 308 nm excimer laser, clobetasol spray, and calcitriol ointment: a case series.

PubMed

Wong, Jillian W; Nguyen, Tien V; Bhutani, Tina; Koo, John Y M

2012-08-01

Psoriasis is a chronic inflammatory skin disease that is characterized by thickened red plaques covered with silvery scales. Excimer laser therapy is a cutting-edge advancement in UVB phototherapy. In contrast to traditional phototherapy, the 308 nm excimer laser only targets psoriasis plaques, while it spares uninvolved skin. It allows for treatment with a supra-erythmogenic dose of UVB irradiation. Targeted UVB therapy is a possible treatment especially for many who have failed topical treatments, systemic therapy, and traditional phototherapy. For safe and effective psoriasis treatment, a combination of therapies may be used, including a combination of laser treatment with topical medications. We present two cases demonstrating effective treatment with excimer laser in conjunction with clobetasol spray and calcitriol ointment for 12 weeks. Long-term near-clearance of psoriasis was sustained after 6 months and one-year follow up periods without further therapy.

New ultra-high resolution dye laser spectrometer utilizing a non-tunable reference resonator

NASA Astrophysics Data System (ADS)

Helmcke, J.; Snyder, J. J.; Morinaga, A.; Mensing, F.; Gläser, M.

1987-06-01

A new dye laser spectrometer utilizing a non-tunable reference resonator is described. The resonator consists of two Zerodur mirrors optically contacted to a Zerodur spacer. Frequency scanning of the laser is provided by acoustooptic modulation. Residual drifts of the resonator frequency — measured on line — are compensated automatically by corresponding corrections of the modulation frequency. The stability during several hours and the resettability of the dye laser frequency are±2.5 kHz and±10 kHz, respectively.

Efficacious insect and disease control with laser-guided air-assisted sprayer

USDA-ARS?s Scientific Manuscript database

Efficacy of a newly developed air-assisted variable-rate sprayer was investigated for the control of arthropod pests and plant diseases in six commercial fields. The sprayer was integrated with a high-speed laser scanning sensor, a custom-designed signal processing program, an automatic flow control...

Development of a laser-guided embedded-computer-controlled air-assisted precision sprayer

USDA-ARS?s Scientific Manuscript database

An embedded computer-controlled, laser-guided, air-assisted, variable-rate precision sprayer was developed to automatically adjust spray outputs on both sides of the sprayer to match presence, size, shape, and foliage density of tree crops. The sprayer was the integration of an embedded computer, a ...

Dust-concentration measurement based on Mie scattering of a laser beam

PubMed Central

Yu, Xiaoyu; Shi, Yunbo; Wang, Tian; Sun, Xu

2017-01-01

To realize automatic measurement of the concentration of dust particles in the air, a theory for dust concentration measurement was developed, and a system was designed to implement the dust concentration measurement method based on laser scattering. In the study, the principle of dust concentration detection using laser scattering is studied, and the detection basis of Mie scattering theory is determined. Through simulation, the influence of the incident laser wavelength, dust particle diameter, and refractive index of dust particles on the scattered light intensity distribution are obtained for determining the scattered light intensity curves of single suspended dust particles under different characteristic parameters. A genetic algorithm was used to study the inverse particle size distribution, and the reliability of the measurement system design is proven theoretically. The dust concentration detection system, which includes a laser system, computer circuitry, air flow system, and control system, was then implemented according to the parameters obtained from the theoretical analysis. The performance of the designed system was evaluated. Experimental results show that the system performance was stable and reliable, resulting in high-precision automatic dust concentration measurement with strong anti-interference ability. PMID:28767662

Chinese Journal of Lasers (Selected Articles),

DTIC Science & Technology

1986-04-22

properties We first investigated silicate based glasses, then the other inorganic glasses such as borate, phosphate, germanate. tellurate ...of the growth of high melting temperature I.~ oxides, several upward pulling single crystal furnaces with nigh precision mechanical movement and high...automatic electronic weighting systems, and programmable automatic movement correction systems. The reliability of most of these control systems

Optical Radiation: Susceptibility and Countermeasures

DTIC Science & Technology

1998-12-01

1995). "Early Visual Acuity Side Effects After Laser Retinal Photocoagulation in Diabetic Retinopathy ," W.D. Kosnik, L. Marouf, and M. Myers...tests. The automatic positioner (AMPS) coupled with the automatic optical test system (PEATS) permits timely and consistent evaluation of candidate...Science and Engineering OR:S&C Optical Radiation: Susceptibility and Countermeasures OSADS Optical Signature, Acquisition, and Detection System

Combined 595-nm and 1,064-nm laser irradiation of recalcitrant and hypertrophic port-wine stains in children and adults.

PubMed

Alster, Tina S; Tanzi, Elizabeth L

2009-06-01

Although pulsed dye laser (PDL) treatment of port-wine stain (PWS) has long been proven safe and effective, incomplete clearance of these vascular malformations can be problematic. In addition, advanced PWS with deeper coloration and tissue hypertrophy can be particularly difficult to treat because of the superficial dermal penetration of 585- to 595-nm light. The purpose of this study was to evaluate the safety and efficacy of a novel device that delivers sequential pulses of 595- and 1,064-nm wavelengths in the treatment of recalcitrant and hypertrophic PWS. Twenty-five children and adults (skin phototypes I-III) with recalcitrant or hypertrophic PWS showing incomplete clearance after 10 prior PDL treatments were included in the study. Successive treatments using a 595-nm PDL and a 1,064-nm neodymium-doped yttrium-aluminum-garnet (Nd:YAG) laser were delivered at 6- to 8-week intervals. Two masked assessors determined clinical improvement of treatment areas using independent evaluation of comparative photographs at baseline and 3 months after treatment using a standard quartile grading scale. The use of dual 595-/1,064-nm wavelengths provided continued improvement of PWS that were previously recalcitrant to ongoing PDL therapy. Side effects were limited to transient erythema, edema, and mild purpura. Rare vesicle formation was observed, with no subsequent scarring or undesirable pigmentary changes. The novel dual 595-nm PDL and 1,064-nm Nd:YAG laser is an effective treatment for PWS that are recalcitrant to PDL therapy alone.

Analysis of separation test for automatic brake adjuster based on linear radon transformation

NASA Astrophysics Data System (ADS)

Luo, Zai; Jiang, Wensong; Guo, Bin; Fan, Weijun; Lu, Yi

2015-01-01

The linear Radon transformation is applied to extract inflection points for online test system under the noise conditions. The linear Radon transformation has a strong ability of anti-noise and anti-interference by fitting the online test curve in several parts, which makes it easy to handle consecutive inflection points. We applied the linear Radon transformation to the separation test system to solve the separating clearance of automatic brake adjuster. The experimental results show that the feature point extraction error of the gradient maximum optimal method is approximately equal to ±0.100, while the feature point extraction error of linear Radon transformation method can reach to ±0.010, which has a lower error than the former one. In addition, the linear Radon transformation is robust.

A bootstrapped, low-noise, and high-gain photodetector for shot noise measurement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Haijun; Yang, Wenhai; Li, Zhixiu

2014-01-15

We presented a low-noise, high-gain photodetector based on the bootstrap structure and the L-C (inductance and capacitance) combination. Electronic characteristics of the photodetector, including electronic noise, gain and frequency response, and dynamic range, were verified through a single-frequency Nd:YVO{sub 4} laser at 1064 nm with coherent output. The measured shot noise of 50 μW laser was 13 dB above the electronic noise at the analysis frequency of 2 MHz, and 10 dB at 3 MHz. And a maximum clearance of 28 dB at 2 MHz was achieved when 1.52 mW laser was illuminated. In addition, the photodetector showed excellent linearitiesmore » for both DC and AC amplifications in the laser power range between 12.5 μW and 1.52 mW.« less

Prospective Evaluation of the Safety and Efficacy of a 1060-nm Large Spot Size, Vacuum-Assisted Hair Removal Diode Laser System in Asian/Pacific Fitzpatrick's Skin Types IV-V Patients.

PubMed

Tahiliani, Sushil T; Tahiliani, Harsh S

2016-11-01

Laser-based photoepilation of dark skin types demands a delicate combination of appropriate light wavelengths and spot size to achieve optimal epidermal-to-follicular energy absorption ratios. This prospective study assessed the axillary, arm, thigh, and back hair clearing ef cacy of the LightSheer In nity 1060 nm diode laser in 10 Fitzpatrick skin type IV-V patients. Each area was treated up to ve times, at 4-6-week intervals, after which immediate skin responses and adverse events were recorded. Hair count, color and coarseness were assessed before each treatment session, as well as 1, 3, and 6 months following the last session. Both patients and the treating physician rated the degree of improvement with time, and patients also ranked their satisfaction with the treatment outcome. Percent hair reduction from baseline gradually increased with treatment and peaked at 74.6%, 68.4%, and 65.7% for axillary, arm and thigh regions, respectively, 6 months following the last treatment session. Baseline hair growth patterns precluded effective selection of a representative area for hair counting. Patients satisfaction was consistently higher for axillary hair clearance rates, followed by thigh and arm responses. Throughout the follow-up period, the investigator rated 50-67% of the treated axillae as presenting "good" or "very good" hair clearance, and provided similar ratings for 67% of the treated thigh regions at both the 1 and 6 month follow-up sessions. Immediate responses to treatment were mild to moderate and short-lived and no incidents of brosis or scarring were reported. Taken together, the LightSheer In nity 1060 HS Handpiece provided for an ideal ef cacy-safety balance in treating dark-skinned patients, providing for long-term hair clearance with minimal downtime. J Drugs Dermatol. 2016;15(11):1427-1434.

Automatic irradiation control by an optical feedback technique for selective retina treatment (SRT) in a rabbit model

NASA Astrophysics Data System (ADS)

Seifert, Eric; Roh, Young-Jung; Fritz, Andreas; Park, Young Gun; Kang, Seungbum; Theisen-Kunde, Dirk; Brinkmann, Ralf

2013-06-01

Selective Retina Therapy (SRT) targets the Retinal Pigment Epithelium (RPE) without effecting neighboring layers as the photoreceptors or the choroid. SRT related RPE defects are ophthalmoscopically invisible. Owing to this invisibility and the variation of the threshold radiant exposure for RPE damage the treating physician does not know whether the treatment was successful or not. Thus measurement techniques enabling a correct dosing are a demanded element in SRT devices. The acquired signal can be used for monitoring or automatic irradiation control. Existing monitoring techniques are based on the detection of micro-bubbles. These bubbles are the origin of RPE cell damage for pulse durations in the ns and μs time regime 5μs. The detection can be performed by optical or acoustical approaches. Monitoring based on an acoustical approach has already been used to study the beneficial effects of SRT on diabetic macula edema and central serous retinopathy. We have developed a first real time feedback technique able to detect micro-bubble induced characteristics in the backscattered laser light fast enough to cease the laser irradiation within a burst. Therefore the laser energy within a burst of at most 30 pulses is increased linearly with every pulse. The laser irradiation is ceased as soon as micro-bubbles are detected. With this automatic approach it was possible to observe invisible lesions, an intact photoreceptor layer and a reconstruction of the RPE within one week.

Double Pass 595 nm Pulsed Dye Laser Does Not Enhance the Efficacy of Port Wine Stains Compared with Single Pass: A Randomized Comparison with Histological Examination.

PubMed

Yu, Wenxin; Zhu, Jiafang; Wang, Lizhen; Qiu, Yajing; Chen, Yijie; Yang, Xi; Chang, Lei; Ma, Gang; Lin, Xiaoxi

2018-03-27

To compare the efficacy and safety of double-pass pulsed dye laser (DWL) and single-pass PDL (SWL) in treating virgin port wine stain (PWS). The increase in the extent of vascular damage attributed to the use of double-pass techniques for PWS remains inconclusive. A prospective, side-by-side comparison with a histological study for virgin PWS is still lacking. Twenty-one patients (11 flat PWS, 10 hypertrophic PWS) with untreated PWS underwent 3 treatments at 2-month intervals. Each PWS was divided into three treatment sites: SWL, DWL, and untreated control. Chromametric and visual evaluation of the efficacy and evaluation of side effects were conducted 3 months after final treatment. Biopsies were taken at the treated sites immediately posttreatment. Chromametric and visual evaluation suggested that DWL sites showed no significant improvement compared with SWL (p > 0.05) in treating PWS. The mean depth of photothermal damage to the vessels was limited to a maximum of 0.36-0.41 mm in both SWL and DWL sides. Permanent side effects were not observed in any patients. Double-pass PDL does not enhance PWS clearance. To improve the clearance of PWS lesions, either the depth of laser penetration should be increased or greater photothermal damage to vessels should be generated.

KrF laser amplifier with phase-conjugate Brillouin retroreflectors.

PubMed

Gower, M C

1982-09-01

We have demonstrated the use of phase-conjugate stimulated Brillouin scattering mirrors to produce high-quality, short-pulse KrF laser beams from angular multiplexed and regenerative amplifiers. The mirror was also shown to isolate systems optically from amplifier spontaneous emission. Automatic alignment of targets using this mirror as a retroreflector was also demonstrated.

Co-Registration of DSMs Generated by Uav and Terrestrial Laser Scanning Systems

NASA Astrophysics Data System (ADS)

Ancil Persad, Ravi; Armenakis, Costas

2016-06-01

An approach for the co-registration of Digital Surface Models (DSMs) derived from Unmanned Aerial Vehicles (UAVs) and Terrestrial Laser Scanners (TLS) is proposed. Specifically, a wavelet-based feature descriptor for matching surface keypoints on the 2.5D DSMs is developed. DSMs are useful in wide-scope of various applications such as 3D building modelling and reconstruction, cultural heritage, urban and environmental planning, aircraft navigation/path routing, accident and crime scene reconstruction, mining as well as, topographic map revision and change detection. For these listed applications, it is not uncommon that there will be a need for automatically aligning multi-temporal DSMs which may have been acquired from multiple sensors, with different specifications over a period of time, and may have various overlaps. Terrestrial laser scanners usually capture urban facades in an accurate manner; however this is not the case for building roof structures. On the other hand, vertical photography from UAVs can capture the roofs. Therefore, the automatic fusion of UAV and laser-scanning based DSMs is addressed here as it serves various geospatial applications.

Successful Treatment of Tattoo-Induced Pseudolymphoma with Sequential Ablative Fractional Resurfacing Followed by Q-Switched Nd: YAG 532 nm Laser

PubMed Central

Lucinda, Tan Siyun; Hazel, Oon Hwee Boon; Joyce, Lee Siong Siong; Hon, Chua Sze

2013-01-01

Decorative tattooing has been linked with a range of complications, with pseudolymphoma being unusual and challenging to manage. We report a case of tattoo-induced pseudolymphoma, who failed treatment with potent topical and intralesional steroids. She responded well to sequential treatment with ablative fractional resurfacing (AFR) followed by Q-Switched (QS) Nd:YAG 532 nm laser. Interestingly, we managed to document the clearance of her tattoo pigments after laser treatments on histology and would like to highlight the use of special stains such as the Grocott's Methenamine Silver (GMS) stain as a useful method to assess the presence of tattoo pigment in cases where dense inflammatory infiltrates are present. PMID:24470721

Re-recognizing serological change patterns and antiviral therapy opportunity of patients with acute hepatitis B through highly sensitive detection technology.

PubMed

Ma, Haixia; Gao, Min; Li, Jia; Zhou, Li; Guo, Jie; Liu, Junjuan; Han, Xu; Zhai, Lu; Wu, Ting

2016-11-01

This study was conducted to re-recognize serological change patterns of patients with acute hepatitis B (AHB) by a highly sensitive detection technology, as well as to explore methods to select the optimal treatment opportunity. The biochemical and virological parameters of 558 AHB patients were analyzed retrospectively. The serological markers of hepatitis B virus and HBV DNA were detected by electrochemiluminescence immunoassay and automatic real-time fluorescent quantitative PCR, respectively. At baseline, the positive rate of hepatitis B surface antigen (HBsAg) (86.2%) was significantly higher than the positive rate of HBV DNA (51.9%). Among the 58 patients with HBsAg-negative AHB, 16 were detected with trace amounts of HBV DNA at baseline. At 12 weeks, the HBsAg of 43 cases remained positive, and the mean level of HBsAg was 587.5IU/mL±313.4IU/mL. A total of 18 patients with HBsAg levels greater than 1500IU/mL at 12 weeks received interferon α-1b treatment and achieved HBsAg clearance within 24 weeks. Unlike traditional changing patterns, the clearance of HBV DNA in peripheral circulation for a few patients with AHB occurred later than HBsAg clearance. Detection of HBV DNA in peripheral circulation by highly sensitive detection technology could provide a diagnostic basis for those AHB patients who rapidly achieved HBsAg clearance before achieving HBV DNA clearance in their peripheral circulation and prevent misdiagnosis. Dynamic monitoring of the changes in HBsAg levels through highly sensitive detection technology could be used as a guide for the timely adoption of antiviral treatment with interferon and then AHB chronicity would be prevented. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

A Laser-Based Measuring System for Online Quality Control of Car Engine Block.

PubMed

Li, Xing-Qiang; Wang, Zhong; Fu, Lu-Hua

2016-11-08

For online quality control of car engine production, pneumatic measurement instrument plays an unshakeable role in measuring diameters inside engine block because of its portability and high-accuracy. To the limitation of its measuring principle, however, the working space between the pneumatic device and measured surface is too small to require manual operation. This lowers the measuring efficiency and becomes an obstacle to perform automatic measurement. In this article, a high-speed, automatic measuring system is proposed to take the place of pneumatic devices by using a laser-based measuring unit. The measuring unit is considered as a set of several measuring modules, where each of them acts like a single bore gauge and is made of four laser triangulation sensors (LTSs), which are installed on different positions and in opposite directions. The spatial relationship among these LTSs was calibrated before measurements. Sampling points from measured shaft holes can be collected by the measuring unit. A unified mathematical model was established for both calibration and measurement. Based on the established model, the relative pose between the measuring unit and measured workpiece does not impact the measuring accuracy. This frees the measuring unit from accurate positioning or adjustment, and makes it possible to realize fast and automatic measurement. The proposed system and method were finally validated by experiments.

The role and mechanics of dendritic cells in tumor antigen acquisition and presentation following laser immunotherapy

NASA Astrophysics Data System (ADS)

Laverty, Sean M.; Dawkins, Bryan A.; Chen, Wei R.

2018-02-01

We extend our model of the antitumor immune response initiated by laser-immunotherapy treatment to more closely examine key steps in the immune response 1) tumor antigen acquisition by antigen-presenting dendritic cells (DCs) and 2) cytotoxic T cell (CTL) priming by lymphatic DCs. Specifically we explore the formation of DC-CTL complexes that lead to CTL priming. We find that the bias in the dissociation rate of the complex influences the outcome of treatment. In particular, a bias towards priming favors a rapid activated CTL response and the clearance of tumors.

Photodynamic therapy in combination with CO2 laser for the treatment of Bowen's disease.

PubMed

Cai, Hong; Wang, Yi-xia; Zheng, Ji-Chun; Sun, Ping; Yang, Zhi-yong; Li, Yuan-li; Liu, Xiao-yong; Li, Qiang; Liu, Wei

2015-07-01

Photodynamic therapy (PDT) involves the activation of a previously administered photosensitizing agent by visible light to induce tumor necrosis. Photosensitizers are topically applied in the treatment of skin tumors to avoid systemic side effects. In this study, we evaluated the feasibility and efficacy of aminolevulinic acid (ALA) as a photosensitizer (ALA-PDT) in combination with CO2 laser in the treatment of Bowen's disease (BD; intraepithelial squamous cell carcinoma). Twenty-two lesions from 18 patients were randomized into two groups: 11 lesions were treated with topical ALA-PDT (180 J/cm(2) at 100 mW/cm(2)) + CO2 laser for one to three sessions. The remaining 11 lesions were treated with CO2 laser alone, serving as control group. All patients were reviewed at ≤1-week intervals. Biopsies were taken from BD lesions prior to treatment. The initial evaluation was undertaken 1 month after treatment, and biopsies were harvested for histological evaluation. Patients who did not respond to the three sessions of treatment were referred to surgical treatment. In the ALA-PDT + CO2 laser group, 72.73 % (8/11) of BD lesions showed complete remission, with an overall clearance of 90.91 %, and only one recurred (9 %) during follow-up. Local side effects included mild erythema, edema, erosion, and burning and/or stinging sensation. No systemic side effects were observed. In the control group, 63.63 % (7/11) of lesions had complete remission and the overall clearance was 54.55 %. However, five lesions (45.45 %) had recurrence. Local side effects included mild to moderate edema, erosion, ulceration, delayed healing, prolonged pain, and scarring. There existed a significant difference in recurrence rate between the two groups (P < 0.05). Moreover, after ALA-PDT plus CO2 laser treatment, complete necrosis was observed in responsive lesions, and 3 months later, the atypical BD cells were replaced by normal keratinocytes. Topical ALA-PDT in combination with CO2 laser is safe, effective, and is associated with low recurrence and reduced side effects.

Multi Sensor Data Integration for AN Accurate 3d Model Generation

NASA Astrophysics Data System (ADS)

Chhatkuli, S.; Satoh, T.; Tachibana, K.

2015-05-01

The aim of this paper is to introduce a novel technique of data integration between two different data sets, i.e. laser scanned RGB point cloud and oblique imageries derived 3D model, to create a 3D model with more details and better accuracy. In general, aerial imageries are used to create a 3D city model. Aerial imageries produce an overall decent 3D city models and generally suit to generate 3D model of building roof and some non-complex terrain. However, the automatically generated 3D model, from aerial imageries, generally suffers from the lack of accuracy in deriving the 3D model of road under the bridges, details under tree canopy, isolated trees, etc. Moreover, the automatically generated 3D model from aerial imageries also suffers from undulated road surfaces, non-conforming building shapes, loss of minute details like street furniture, etc. in many cases. On the other hand, laser scanned data and images taken from mobile vehicle platform can produce more detailed 3D road model, street furniture model, 3D model of details under bridge, etc. However, laser scanned data and images from mobile vehicle are not suitable to acquire detailed 3D model of tall buildings, roof tops, and so forth. Our proposed approach to integrate multi sensor data compensated each other's weakness and helped to create a very detailed 3D model with better accuracy. Moreover, the additional details like isolated trees, street furniture, etc. which were missing in the original 3D model derived from aerial imageries could also be integrated in the final model automatically. During the process, the noise in the laser scanned data for example people, vehicles etc. on the road were also automatically removed. Hence, even though the two dataset were acquired in different time period the integrated data set or the final 3D model was generally noise free and without unnecessary details.

Automatic variable selection method and a comparison for quantitative analysis in laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Duan, Fajie; Fu, Xiao; Jiang, Jiajia; Huang, Tingting; Ma, Ling; Zhang, Cong

2018-05-01

In this work, an automatic variable selection method for quantitative analysis of soil samples using laser-induced breakdown spectroscopy (LIBS) is proposed, which is based on full spectrum correction (FSC) and modified iterative predictor weighting-partial least squares (mIPW-PLS). The method features automatic selection without artificial processes. To illustrate the feasibility and effectiveness of the method, a comparison with genetic algorithm (GA) and successive projections algorithm (SPA) for different elements (copper, barium and chromium) detection in soil was implemented. The experimental results showed that all the three methods could accomplish variable selection effectively, among which FSC-mIPW-PLS required significantly shorter computation time (12 s approximately for 40,000 initial variables) than the others. Moreover, improved quantification models were got with variable selection approaches. The root mean square errors of prediction (RMSEP) of models utilizing the new method were 27.47 (copper), 37.15 (barium) and 39.70 (chromium) mg/kg, which showed comparable prediction effect with GA and SPA.

Automatic Feature Detection, Description and Matching from Mobile Laser Scanning Data and Aerial Imagery

NASA Astrophysics Data System (ADS)

Hussnain, Zille; Oude Elberink, Sander; Vosselman, George

2016-06-01

In mobile laser scanning systems, the platform's position is measured by GNSS and IMU, which is often not reliable in urban areas. Consequently, derived Mobile Laser Scanning Point Cloud (MLSPC) lacks expected positioning reliability and accuracy. Many of the current solutions are either semi-automatic or unable to achieve pixel level accuracy. We propose an automatic feature extraction method which involves utilizing corresponding aerial images as a reference data set. The proposed method comprise three steps; image feature detection, description and matching between corresponding patches of nadir aerial and MLSPC ortho images. In the data pre-processing step the MLSPC is patch-wise cropped and converted to ortho images. Furthermore, each aerial image patch covering the area of the corresponding MLSPC patch is also cropped from the aerial image. For feature detection, we implemented an adaptive variant of Harris-operator to automatically detect corner feature points on the vertices of road markings. In feature description phase, we used the LATCH binary descriptor, which is robust to data from different sensors. For descriptor matching, we developed an outlier filtering technique, which exploits the arrangements of relative Euclidean-distances and angles between corresponding sets of feature points. We found that the positioning accuracy of the computed correspondence has achieved the pixel level accuracy, where the image resolution is 12cm. Furthermore, the developed approach is reliable when enough road markings are available in the data sets. We conclude that, in urban areas, the developed approach can reliably extract features necessary to improve the MLSPC accuracy to pixel level.

Semi-Automatic Modelling of Building FAÇADES with Shape Grammars Using Historic Building Information Modelling

NASA Astrophysics Data System (ADS)

Dore, C.; Murphy, M.

2013-02-01

This paper outlines a new approach for generating digital heritage models from laser scan or photogrammetric data using Historic Building Information Modelling (HBIM). HBIM is a plug-in for Building Information Modelling (BIM) software that uses parametric library objects and procedural modelling techniques to automate the modelling stage. The HBIM process involves a reverse engineering solution whereby parametric interactive objects representing architectural elements are mapped onto laser scan or photogrammetric survey data. A library of parametric architectural objects has been designed from historic manuscripts and architectural pattern books. These parametric objects were built using an embedded programming language within the ArchiCAD BIM software called Geometric Description Language (GDL). Procedural modelling techniques have been implemented with the same language to create a parametric building façade which automatically combines library objects based on architectural rules and proportions. Different configurations of the façade are controlled by user parameter adjustment. The automatically positioned elements of the façade can be subsequently refined using graphical editing while overlaying the model with orthographic imagery. Along with this semi-automatic method for generating façade models, manual plotting of library objects can also be used to generate a BIM model from survey data. After the 3D model has been completed conservation documents such as plans, sections, elevations and 3D views can be automatically generated for conservation projects.

Free-space QKD system hacking by wavelength control using an external laser.

PubMed

Lee, Min Soo; Woo, Min Ki; Jung, Jisung; Kim, Yong-Su; Han, Sang-Wook; Moon, Sung

2017-05-15

We develop a way to hack free-space quantum key distribution (QKD) systems by changing the wavelength of the quantum signal laser using an external laser. Most free-space QKD systems use four distinct lasers for each polarization, thereby making the characteristics of each laser indistinguishable. We also discover a side-channel that can distinguish the lasers by using an external laser. Our hacking scheme identifies the lasers by automatically applying the external laser to each signal laser at different intensities and detecting the wavelength variation according to the amount of incident external laser power. We conduct a proof-of-principle experiment to verify the proposed hacking structure and confirm that the wavelength varies by several gigahertzes to several nanometers, depending on the intensity of the external laser. The risk of hacking is successfully proven through the experimental results. Methods for prevention are also suggested.

The development and progress of XeCl Excimer laser system

NASA Astrophysics Data System (ADS)

Zhang, Yongsheng; Ma, Lianying; Wang, Dahui; Zhao, Xueqing; Zhu, Yongxiang; Hu, Yun; Qian, Hang; Shao, Bibo; Yi, Aiping; Liu, Jingru

2015-05-01

A large angularly multiplexed XeCl Excimer laser system is under development at the Northwest Institute of Nuclear Technology (NINT). It is designed to explore the technical issues of uniform and controllable target illumination. Short wavelength, uniform and controllable target illumination is the fundamental requirement of high energy density physics research using large laser facility. With broadband, extended light source and multi-beam overlapping techniques, rare gas halide Excimer laser facility will provide uniform target illumination theoretically. Angular multiplexing and image relay techniques are briefly reviewed and some of the limitations are examined to put it more practical. The system consists of a commercial oscillator front end, three gas discharge amplifiers, two electron beam pumped amplifiers and the optics required to relay, encode and decode the laser beam. An 18 lens array targeting optics direct and focus the laser in the vacuum target chamber. The system is operational and currently undergoing tests. The total 18 beams output energy is more than 100J and the pulse width is 7ns (FWHM), the intensities on the target will exceed 1013W/cm2. The aberration of off-axis imaging optics at main amplifier should be minimized to improve the final image quality at the target. Automatic computer controlled alignment of the whole system is vital to efficiency and stability of the laser system, an array of automatic alignment model is under test and will be incorporated in the system soon.

Hypertrichotic Becker's nevi treated with combination 1,550 nm non-ablative fractional photothermolysis and laser hair removal.

PubMed

Balaraman, Brundha; Friedman, Paul M

2016-04-01

The removal of Becker's nevi poses a significant challenge due to limited available therapeutic options and increased risk of adverse effects, including scarring and dyspigmentation. Herein, we present the use of the non-ablative fractional photothermolysis in combination with laser hair removal for the treatment of hypertrichotic Becker's nevi. Retrospective analysis of three patients with Becker's nevi revealed that two patients with hypertrichotic Becker's nevi had greater than 75% clearance with combination therapy, and one patient with atrichotic Becker's nevus had a similar result with monotherapy non-ablative fractional photothermolysis. This report demonstrates the utility and safety of combination non-ablative fractional resurfacing and laser hair removal for the treatment of hypertrichotic Becker's nevi, and monotherapy non-ablative fractional photothermolysis for atrichotic Becker's nevi. Further comparative studies are necessary to determine optimal laser parameters, treatment schedules, and response duration. © 2016 Wiley Periodicals, Inc.

Arbitrary temporal shape pulsed fiber laser based on SPGD algorithm

NASA Astrophysics Data System (ADS)

Jiang, Min; Su, Rongtao; Zhang, Pengfei; Zhou, Pu

2018-06-01

A novel adaptive pulse shaping method for a pulsed master oscillator power amplifier fiber laser to deliver an arbitrary pulse shape is demonstrated. Numerical simulation has been performed to validate the feasibility of the scheme and provide meaningful guidance for the design of the algorithm control parameters. In the proof-of-concept experiment, information on the temporal property of the laser is exchanged and evaluated through a local area network, and the laser adjusted the parameters of the seed laser according to the monitored output of the system automatically. Various pulse shapes, including a rectangular shape, ‘M’ shape, and elliptical shape are achieved through experimental iterations.

Non-ablative scar revision using a long pulsed frequency doubled Nd:YAG laser.

PubMed

Cassuto, Daniel; Emanuelli, Guglielmo

2003-12-01

Unsightly scars often are the only reminder of a previous surgical or traumatic wound. Surgical or ablative scar revision is sought by patients, sometimes unnecessarily. When the aesthetic drawback is mainly a result of hypervascularity or hyperpigmentation, these problems can be specifically targeted with a wavelength that is well absorbed by the two above mentioned chromophores. Some degree of epidermal tightening can also be achieved, which is sometimes useful in slightly atrophic scars. The average improvement after 2-3 sessions was 81% (75%-100%) clearance, as judged by an independent observer who reviewed pre- and post-treatment photographs. No undesired effects were reported. All our patients were satisfied and required no further treatment. Selective photothermolysis by means of a long pulsed frequency doubled Nd:YAG laser (DioLite 532, IRIDEX Corporation, Mountain View, CA, USA) was used to eliminate the unsightly vascular and pigmented components of 23 mature scars (scars older than 2 years) in 22 consecutive patients. Energy densities of 17-22 j/cm2 were used with a 500 micron spot, or 65-90 j/cm2 with a 200 micron spot. overall scar clearance averaged 81% after 2.4 treatments. Facial scars showed the best clearance averaging 94% after 2 treatments. Inframammary scars were the most difficult to clear averaging 46%. Postoperative undesired effects were immediate erythema and swelling that subsided within 2-10 hours and microcrusting on 19/22 (88%) patients that resolved within one week. No other temporary or permanent undesired effects such as purpura, hypo- or hyperpigmentation were noticed, even in patients with darker skin types.

a New Approach for the Semi-Automatic Texture Generation of the Buildings Facades, from Terrestrial Laser Scanner Data

NASA Astrophysics Data System (ADS)

Oniga, E.

2012-07-01

The result of the terrestrial laser scanning is an impressive number of spatial points, each of them being characterized as position by the X, Y and Z co-ordinates, by the value of the laser reflectance and their real color, expressed as RGB (Red, Green, Blue) values. The color code for each LIDAR point is taken from the georeferenced digital images, taken with a high resolution panoramic camera incorporated in the scanner system. In this article I propose a new algorithm for the semiautomatic texture generation, using the color information, the RGB values of every point that has been taken by terrestrial laser scanning technology and the 3D surfaces defining the buildings facades, generated with the Leica Cyclone software. The first step is when the operator defines the limiting value, i.e. the minimum distance between a point and the closest surface. The second step consists in calculating the distances, or the perpendiculars drawn from each point to the closest surface. In the third step we associate the points whose 3D coordinates are known, to every surface, depending on the limiting value. The fourth step consists in computing the Voronoi diagram for the points that belong to a surface. The final step brings automatic association between the RGB value of the color code and the corresponding polygon of the Voronoi diagram. The advantage of using this algorithm is that we can obtain, in a semi-automatic manner, a photorealistic 3D model of the building.

Efficacy of the Q-switched Neodymium: Yttrium Aluminum Garnet Laser in the Treatment of Blue-black Amateur and Professional Tattoos.

PubMed

Lakshmi, Chembolli; Krishnaswamy, Gayathri

2015-01-01

Q-switched neodymium: yttrium aluminum garnet (Nd: YAG) laser at a wavelength of 1064 nm primarily targets dermal melanin and black tattoo ink. Recent studies have shown that this laser is effective in treating black tattoos. There are few studies conducted in India for the same. The aim was to assess the effectiveness of Q-switched Nd: YAG laser (QSNYL) in the treatment of blue-black tattoos following 3 treatment sessions. This study, a prospective interventional study included a total of 12 blue-black tattoos. Following informed consent for the procedure, as well as for photographs, a questionnaire was administered, and improvement perceived by the patient was recorded. In addition, global assessment score (GAS) by a blinded physician was also recorded. Photographs were taken at baseline and at every follow-up. Each patient underwent three treatment sessions with 1064 nm QSNYL at 4-6 weekly intervals. Fluences ranged from 1.8 to 9 J/cm(2). The follow-up was done monthly for 4 months from the first treatment session. The response was assessed by patient assessment (PA) and GAS by comparing photographs. After three treatment sessions, although no patient achieved clearance, most patients showed good response with few adverse effects. An average of 64.1% (GAS) and 54.2% (PA) improvement was observed in 12 tattoos. Tattoos more than 10-year-old showed quicker clearing than those less than 10-year-old. Amateur tattoos also showed a better response in comparison to professional tattoos. Totally, 1064 nm QSNYL is safe and effective for lightening blue-black tattoos in pigmented Indian skin. All patients achieved near complete clearance following the continuation of treatment (an average of six sessions) although this was spaced at longer intervals.

Topical application of ALA PDT for the treatment of moderate to severe acne vulgaris

NASA Astrophysics Data System (ADS)

Wang, Xiu-Li; Wang, Hong-Wei; Zhang, Ling-Lin; Su, Lina; Guo, Ming-Xia; Huang, Zheng

2009-06-01

Objectives: To evaluate the effectiveness of topical 5-aminolevulinic acid (ALA)- medicated photodynamic therapy (ALA PDT) for the treatment of moderate to severe acne vulgaris. Methods: Sixteen Chinese patients with moderate to severe facial acne were treated with 1-3 courses of ALA PDT. ALA cream (3%) was freshly prepared and applied to acne lesions for 3-4 h. The lesions were irradiated by a 635 nm diode laser at dose levels of 60 - 80 J/cm2 at 100 mW/cm2. Clinical assessments were conducted before and after treatment up to 3 months. Results: All patents showed response to ALA PDT. Complete clearance was seen in 10 patients (62.5%) and partial clearance in 6 patients (37.5%). One case showed recurrence after complete clearance at 2 months and another two showed recurrence after complete clearance at 3 months. However, the number of new lesions were significantly reduced. Adverse effects were minimal. Conclusions: The results of this preliminary clinical study is encouraging. ALA PDT is a simple, safe and useful therapeutic option for the treatment of moderate to severe acne. Further studies to evaluate the treatment with a larger number of patients and for a longer period of follow-up are needed.

Treatment of port wine stains using Pulsed Dye Laser, Erbium YAG Laser, and topical rapamycin (sirolimus)-A randomized controlled trial.

PubMed

Greveling, Karin; Prens, Errol P; van Doorn, Martijn B

2017-01-01

Pulsed Dye Laser (PDL) is currently the gold standard treatment for port wine stains (PWS), although the degree of lesion blanching is variable and often unpredictable. This appears to be due to reformation and reperfusion of blood vessels. Rapamycin has shown potential as an antiangiogenic agent and may prevent the revascularization after PDL treatment. The objective of this study was to evaluate the efficacy of adjuvant use of (commercially available) topical rapamycin after PDL treatment in patients with PWS. We conducted a prospective, intra-patient, randomized controlled trial. Four treatment areas of 1 cm 2 were created in each PWS. PDL-only treatment was compared to the following three treatments: PDL + rapamycin, PDL + Erbium YAG laser ablation of the stratum corneum + rapamycin, and rapamycin monotherapy. We also compared PDL + Erbium YAG + rapamycin with PDL + rapamycin. The primary endpoint was the percentage clearance assessed colorimetrically at 6 months follow-up. Secondary outcomes were photographic evaluation by an expert panel, patient satisfaction, treatment related pain, and safety. Fourteen patients completed the treatment protocol. The highest percentage clearance was achieved with PDL-only treatment (mean [SD] 16% [34]), but there were no statistically significant differences between treatments. The best photographic evaluation and highest patient satisfaction were also achieved with PDL-only treatment, but only the difference between PDL-only and rapamycin monotherapy was statistically significant. The treatment related pain was well tolerated. Application-site pruritus was a frequent occurring adverse event. Allergic contact dermatitis to rapamycin occurred in one patient. There were no serious adverse events. Topical application of the commercially available solution of rapamycin (Rapamune ® 0.1%) as an adjuvant to PDL treatment does not appear to improve PWS blanching. Lasers Surg. Med. 49:104-109, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

An Experimental Investigation of the Flow Physics Associated With End Wall Losses and Large Rotor Tip Clearances as Found in the Rear Stages of a High Pressure Compressor

NASA Technical Reports Server (NTRS)

Berdanier, Reid A.; Key, Nicole L.

2015-01-01

The focus of this work was to characterize the fundamental flow physics and the overall performance effects due to increased rotor tip clearance heights in axial compressors. Data have been collected in the three-stage axial research compressor at Purdue University with a specific focus on analyzing the multistage effects resulting from the tip leakage flow. Three separate rotor tip clearance heights were studied with nominal tip clearance heights of 1.5%, 3.0%, and 4.0% based on a constant annulus height. Overall compressor performance was investigated at four corrected speedlines (100%, 90%, 80%, and 68%) for each of the three tip clearance configurations using total pressure and total temperature rakes distributed throughout the compressor. The results have confirmed results from previous authors showing a decrease of total pressure rise, isentropic efficiency, and stall margin which is approximately linear with increasing tip clearance height. The stall inception mechanisms have also been evaluated at the same corrected speeds for each of the tip clearance configurations. Detailed flow field measurements have been collected at two loading conditions, nominal loading (NL) and high loading (HL), on the 100% corrected speedline for the smallest and largest tip clearance heights (1.5% and 4.0%). Steady detailed radial traverses of total pressure at the exit of each stator row have been supported by flow visualization techniques to identify regions of flow recirculation and separation. Furthermore, detailed radial traverses of time-resolved total pressures at the exit of each rotor row have been measured with a fast-response pressure probe. These data have helped to quantify the size of the leakage flow at the exit of each rotor. Thermal anemometry has also been implemented to evaluate the time-resolved three-dimensional components of velocity throughout the compressor and calculate blockage due to the rotor tip leakage flow throughout the compressor. These measurements have also been used to calculate streamwise vorticity. Time-resolved static pressure measurements have been collected over the rotor tips for all rotors with each of the three tip clearance configurations for up to five loading conditions along the 100% corrected speedline using fast-response piezoresistive pressure sensors. These time-resolved static pressure measurements, as well as the time-resolved total pressures and velocities have helped to reveal a profound influence of the upstream stator vane on the size and shape of the rotor tip leakage flow. Finally, a novel particle image velocimetry (PIV) technique has been developed as a proof-of- concept. In contrast to PIV methods that have been typically been utilized for turbomachinery applications in the past, the method used for this study introduced the laser light through the same access window that was also used to image the flow. This new method addresses potential concerns related to the intrusive laser-introducing techniques that have typically been utilized by other authors in the past. Ultimately, the data collected for this project represent a unique data set which contributes to build a better understanding of the tip leakage flow field and its associated loss mechanisms. These data will facilitate future engine design goals leading to small blade heights in the rear stages of high pressure compressors and aid in the development of new blade designs which are desensitized to the performance penalties attributed to rotor tip leakage flows.

Automatic registration of panoramic image sequence and mobile laser scanning data using semantic features

NASA Astrophysics Data System (ADS)

Li, Jianping; Yang, Bisheng; Chen, Chi; Huang, Ronggang; Dong, Zhen; Xiao, Wen

2018-02-01

Inaccurate exterior orientation parameters (EoPs) between sensors obtained by pre-calibration leads to failure of registration between panoramic image sequence and mobile laser scanning data. To address this challenge, this paper proposes an automatic registration method based on semantic features extracted from panoramic images and point clouds. Firstly, accurate rotation parameters between the panoramic camera and the laser scanner are estimated using GPS and IMU aided structure from motion (SfM). The initial EoPs of panoramic images are obtained at the same time. Secondly, vehicles in panoramic images are extracted by the Faster-RCNN as candidate primitives to be matched with potential corresponding primitives in point clouds according to the initial EoPs. Finally, translation between the panoramic camera and the laser scanner is refined by maximizing the overlapping area of corresponding primitive pairs based on the Particle Swarm Optimization (PSO), resulting in a finer registration between panoramic image sequences and point clouds. Two challenging urban scenes were experimented to assess the proposed method, and the final registration errors of these two scenes were both less than three pixels, which demonstrates a high level of automation, robustness and accuracy.

Precision Targeting With a Tracking Adaptive Optics Scanning Laser Ophthalmoscope

DTIC Science & Technology

2006-01-01

automatic high- resolution mosaic generation, and automatic blink detection and tracking re-lock were also tested. The system has the potential to become an...structures can lead to earlier detection of retinal diseases such as age-related macular degeneration (AMD) and diabetic retinopathy (DR). Combined...optics systems sense perturbations in the detected wave-front and apply corrections to an optical element that flatten the wave-front and allow near

Fast and automatic thermographic material identification for the recycling process

NASA Astrophysics Data System (ADS)

Haferkamp, Heinz; Burmester, Ingo

1998-03-01

Within the framework of the future closed loop recycling process the automatic and economical sorting of plastics is a decisive element. The at the present time available identification and sorting systems are not yet suitable for the sorting of technical plastics since essential demands, as the realization of high recognition reliability and identification rates considering the variety of technical plastics, can not be guaranteed. Therefore the Laser Zentrum Hannover e.V. in cooperation with the Hoerotron GmbH and the Preussag Noell GmbH has carried out investigations on a rapid thermographic and laser-supported material- identification-system for automatic material-sorting- systems. The automatic identification of different engineering plastics coming from electronic or automotive waste is possible. Identification rates up to 10 parts per second are allowed by the effort from fast IR line scanners. The procedure is based on the following principle: within a few milliseconds a spot on the relevant sample is heated by a CO2 laser. The samples different and specific chemical and physical material properties cause different temperature distributions on their surfaces that are measured by a fast IR-linescan system. This 'thermal impulse response' has to be analyzed by means of a computer system. Investigations have shown that it is possible to analyze more than 18 different sorts of plastics at a frequency of 10 Hz. Crucial for the development of such a system is the rapid processing of imaging data, the minimization of interferences caused by oscillating samples geometries, and a wide range of possible additives in plastics in question. One possible application area is sorting of plastics coming from car- and electronic waste recycling.

A Laser-Based Measuring System for Online Quality Control of Car Engine Block

PubMed Central

Li, Xing-Qiang; Wang, Zhong; Fu, Lu-Hua

2016-01-01

For online quality control of car engine production, pneumatic measurement instrument plays an unshakeable role in measuring diameters inside engine block because of its portability and high-accuracy. To the limitation of its measuring principle, however, the working space between the pneumatic device and measured surface is too small to require manual operation. This lowers the measuring efficiency and becomes an obstacle to perform automatic measurement. In this article, a high-speed, automatic measuring system is proposed to take the place of pneumatic devices by using a laser-based measuring unit. The measuring unit is considered as a set of several measuring modules, where each of them acts like a single bore gauge and is made of four laser triangulation sensors (LTSs), which are installed on different positions and in opposite directions. The spatial relationship among these LTSs was calibrated before measurements. Sampling points from measured shaft holes can be collected by the measuring unit. A unified mathematical model was established for both calibration and measurement. Based on the established model, the relative pose between the measuring unit and measured workpiece does not impact the measuring accuracy. This frees the measuring unit from accurate positioning or adjustment, and makes it possible to realize fast and automatic measurement. The proposed system and method were finally validated by experiments. PMID:27834839

Performance of a nonlaser light source for photodynamic therapy

NASA Astrophysics Data System (ADS)

Whitehurst, Colin; Byrne, Karen T.; Morton, Colin; Moore, James V.

1995-03-01

Advances in short arc technology and optical filter coatings led to the design and construction of a table-top light source in 1989; the first viable and cost-effective alternative to a laser. The device can deliver over 3 W within a 30 nm band centered at any wavelength from 200 nm to 1200 nm at fluence rates of over 1 W cm-2. Its relative biological effectiveness (RBE) in vitro has been proven alongside an argon pumped dye laser and a copper vapor pumped dye laser. These in vitro tests showed an efficiency of hematoporphyrin derivative (HPD) induced cellular photoinactivation close to that of the argon/dye laser (RBE 100%), with a mean RBE for the lamp of 87 +/- 3% (p < 0.05). The lamp proved to be superior to that of the copper/dye laser system with an RBE of up to 150% at fluence rates above 50 mWcm-2. In vivo tests show that the extent and depth of tumor necrosis are comparable to that of an argon/dye laser. An in situ bioassay using tumor regrowth delay is currently underway. Early clinical trials show clearance of Bowen's disease and actinic keratosis using the same light fluences as costly PDT lasers.

A retrospective analysis of the influencing factors and complications of Q-switched lasers in tattoo removal in China.

PubMed

Zhang, Mengli; Gong, Xiangdong; Lin, Tong; Wu, Qiuju; Ge, Yiping; Huang, Yuqing; Ge, LiYu

2018-04-01

Q-switched (QS) lasers are the gold standard for tattoo removal. The purpose of the present study was to gain a more comprehensive understanding of the factors that influence the efficacy of QS lasers and their associated complications in the removal of tattoos in China. Clinical data of 266 patients were analyzed retrospectively. The tattoo clearance rate was evaluated using the 4-point scale. The Cox regression model was applied to analyze the factors that affected the efficacy of QS lasers in tattoo removal. In addition, treatment-related adverse reactions were analyzed. The results showed that several variables had a statistically significant effect (p < 0.05) on the efficacy of QS laser-mediated tattoo removal treatment, including the patients' age, the tattoo's age, type, color, or ink density and the number of treatments. A variety of adverse responses occurred during the laser treatment. The overall incidence of adverse responses was approximately 24.06%, including pigmentation, hypopigmentation, bulla formation, allergic reactions, and skin texture changes or hypertrophic scarring. Some factors may influence the efficacy of QS lasers in the treatment of tattoos and certain adverse reactions may occur during this process.

Velocimetry of fast microscopic liquid jets by nanosecond dual-pulse laser illumination for megahertz X-ray free-electron lasers.

PubMed

Grünbein, Marie Luise; Shoeman, Robert L; Doak, R Bruce

2018-03-19

To conduct X-ray Free-Electron Laser (XFEL) measurements at megahertz (MHz) repetition rates, sample solution must be delivered in a micron-sized liquid free-jet moving at up to 100 m/s. This exceeds by over a factor of two the jet speeds measurable with current high-speed camera techniques. Accordingly we have developed and describe herein an alternative jet velocimetry based on dual-pulse nanosecond laser illumination. Three separate implementations are described, including a small laser-diode system that is inexpensive and highly portable. We have also developed and describe analysis techniques to automatically and rapidly extract jet speed from dual-pulse images.

Laser surface alloying of coins for authenticity

NASA Astrophysics Data System (ADS)

Liu, Zhu; Watkins, Kenneth G.; Steen, William M.; Hatherley, P. G.

1997-08-01

This paper presents an exploratory investigation on verifying the feasibility of using a laser surface alloying technique to produce designs in the surface of coinage blanks. The specific aim of the work concerns the production of design features in coins that are difficult to produce by other techniques and which hence act as a barrier to forgery and features which permit automatic recognition in vending machines, particularly as a means of establishing the authenticity of the coins. Coins in many countries today are commonly manufactured from metal composites, where one substrate metal or alloy is coated with another by a process of electrodeposition or by mechanical bonding. The technique here described entails the use of a high power CO2 laser to bring about localized melting of the two layers. Visible distinction between alloyed and unalloyed regions or difference in other physical properties such as conductivity or magnetic properties can be obtained. The work also involved a fundamental study of the influence of the thermal properties of the materials on the CO2 laser alloying process. It was found that the thermal properties such as thermal conductivity of the substrate materials and the difference of the melting points between the coating layer and the substrate materials played an important role in the process. Laser control variables required for localized alloying for different substrate and coatings types were determined. The influence of both thermal properties and laser control variables on alloy type and alloy depth were investigated. Initial work on coin validation showed promising results of an automatic recognition of laser treated coins.

Trans-scleral selective laser trabeculoplasty (SLT) without a gonioscopy lens (Conference Presentation)

NASA Astrophysics Data System (ADS)

Belkin, Michael; Geffen, Noa; Goldenfeld, Modi; Ofir, Shay; Belkin, Avner; Assia, Ehud

2016-03-01

Developing a one-second automatic glaucoma treatment using trans-scleral laser trabeculoplasty (LTP) without a gonioscopy lens Purpose: Developing an LTP device for delivering multiple simultaneous trans-scleral applications of low energy laser irradiation to the trabecular meshwork (TM) for reducing Intraocular Pressure (IOP). Methods: Concept proof: A randomized, masked, controlled one was performed on open angle glaucoma patients. The control group underwent conventional SLT (100 laser spots through a gonioscope for 360 degrees directly on the TM). The trial group underwent irradiation by the same laser at the same irradiation parameters on the sclera overlying the TM. Topical glaucoma therapy was not changed during the 12 months trial. Feasibility trial: Using optimized laser parameters, 60 discrete applications were administered on similar locations of patients' sclera. Results: Concept proof: Trans-scleral applications: (N=15), IOP decrease from 20.21 mmHg before treatment to 16.00 (27.1%) at one year. The corresponding numbers for the control group (n=15), were 21.14 mmHg and 14.30 (23.4%). There was no statistical difference between the two groups in IOP reduction. The complications rate was significantly higher in the control group. Trial 2: IOP was reduced from an of 25.3 mmHg to 19.3 (23.7%) in the 11 patients. Conclusions: Laser coherency, lost in tissue transmission, is not required for the therapeutic effect. The new method will possibly enable treatment of angle closure glaucoma as well as simultaneous applications of all laser spots to the sclera. When used conjointly with target acquisition, will make feasible an automatic glaucoma treatment in less than one second.

Annulus wall boundary layer development in a compressor stage, including the effects of tip clearance

NASA Technical Reports Server (NTRS)

Lakshminarayana, B.; Murthy, K. N. S.; Pouagare, M.; Govindan, T. R.

1983-01-01

The end-wall boundary layer development in a compressor stage, including the inlet guide vane (IGV) passage and the rotor passage, was measured. The measurement upstream of the rotor and inside the IGV passage were carried out with a five-hole probe. The data (blade-to-blade) inside the IGV passage were carried out with a five-hole probe. The data (blade-to-blade) inside the rotor passage were measured using a three-sensor rotating hot-wire below the tip clearance region and "V' configuration probe inside the clearance region. The rotor exit measurements (blade-to-blade) were acquired with a laser Doppler velocimeter. The velocity profiles and the integral properties are presented and interpreted. The boundary layer is comparatively well behaved up to the leading edge of the rotor, beyond which complex interactions result in very unconventional profiles. The momentum thicknesses decrease in the leakage flow region of the rotor. The momentum thicknesses and the limiting streamline angles predicted from a momentum integral technique agree well with the data up to the leading edge of the rotor.

3D model assisted fully automated scanning laser Doppler vibrometer measurements

NASA Astrophysics Data System (ADS)

Sels, Seppe; Ribbens, Bart; Bogaerts, Boris; Peeters, Jeroen; Vanlanduit, Steve

2017-12-01

In this paper, a new fully automated scanning laser Doppler vibrometer (LDV) measurement technique is presented. In contrast to existing scanning LDV techniques which use a 2D camera for the manual selection of sample points, we use a 3D Time-of-Flight camera in combination with a CAD file of the test object to automatically obtain measurements at pre-defined locations. The proposed procedure allows users to test prototypes in a shorter time because physical measurement locations are determined without user interaction. Another benefit from this methodology is that it incorporates automatic mapping between a CAD model and the vibration measurements. This mapping can be used to visualize measurements directly on a 3D CAD model. The proposed method is illustrated with vibration measurements of an unmanned aerial vehicle

Automatic low-order aberration correction based on geometrical optics for slab lasers.

PubMed

Yu, Xin; Dong, Lizhi; Lai, Boheng; Yang, Ping; Liu, Yong; Kong, Qingfeng; Yang, Kangjian; Tang, Guomao; Xu, Bing

2017-02-20

In this paper, we present a method based on geometry optics to simultaneously correct low-order aberrations and reshape the beams of slab lasers. A coaxial optical system with three lenses is adapted. The positions of the three lenses are directly calculated based on the beam parameters detected by wavefront sensors. The initial sizes of the input beams are 1.8  mm×11  mm, and peak-to-valley (PV) values of the wavefront range up to several tens of microns. After automatic correction, the dimensions may reach nearly 22  mm×22  mm as expected, and PV values of the wavefront are less than 2 μm. The effectiveness and precision of this method are verified with experiments.

Automatic neutron dosimetry system based on fluorescent nuclear track detector technology.

PubMed

Akselrod, M S; Fomenko, V V; Bartz, J A; Haslett, T L

2014-10-01

For the first time, the authors are describing an automatic fluorescent nuclear track detector (FNTD) reader for neutron dosimetry. FNTD is a luminescent integrating type of detector made of aluminium oxide crystals that does not require electronics or batteries during irradiation. Non-destructive optical readout of the detector is performed using a confocal laser scanning fluorescence imaging with near-diffraction limited resolution. The fully automatic table-top reader allows one to load up to 216 detectors on a tray, read their engraved IDs using a CCD camera and optical character recognition, scan and process simultaneously two types of images in fluorescent and reflected laser light contrast to eliminate false-positive tracks related to surface and volume crystal imperfections. The FNTD dosimetry system allows one to measure neutron doses from 0.1 mSv to 20 Sv and covers neutron energies from thermal to 20 MeV. The reader is characterised by a robust, compact optical design, fast data processing electronics and user-friendly software. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Automatic analysis for neuron by confocal laser scanning microscope

NASA Astrophysics Data System (ADS)

Satou, Kouhei; Aoki, Yoshimitsu; Mataga, Nobuko; Hensh, Takao K.; Taki, Katuhiko

2005-12-01

The aim of this study is to develop a system that recognizes both the macro- and microscopic configurations of nerve cells and automatically performs the necessary 3-D measurements and functional classification of spines. The acquisition of 3-D images of cranial nerves has been enabled by the use of a confocal laser scanning microscope, although the highly accurate 3-D measurements of the microscopic structures of cranial nerves and their classification based on their configurations have not yet been accomplished. In this study, in order to obtain highly accurate measurements of the microscopic structures of cranial nerves, existing positions of spines were predicted by the 2-D image processing of tomographic images. Next, based on the positions that were predicted on the 2-D images, the positions and configurations of the spines were determined more accurately by 3-D image processing of the volume data. We report the successful construction of an automatic analysis system that uses a coarse-to-fine technique to analyze the microscopic structures of cranial nerves with high speed and accuracy by combining 2-D and 3-D image analyses.

Intelligent surgical laser system configuration and software implementation

NASA Astrophysics Data System (ADS)

Hsueh, Chi-Fu T.; Bille, Josef F.

1992-06-01

An intelligent surgical laser system, which can help the ophthalmologist to achieve higher precision and control during their procedures, has been developed by ISL as model CLS 4001. In addition to the laser and laser delivery system, the system is also equipped with a vision system (IPU), robotics motion control (MCU), and a tracking closed loop system (ETS) that tracks the eye in three dimensions (X, Y and Z). The initial patient setup is computer controlled with guidance from the vision system. The tracking system is automatically engaged when the target is in position. A multi-level tracking system is developed by integrating our vision and tracking systems which have been able to maintain our laser beam precisely on target. The capabilities of the automatic eye setup and the tracking in three dimensions provides for improved accuracy and measurement repeatability. The system is operated through the Surgical Control Unit (SCU). The SCU communicates with the IPU and the MCU through both ethernet and RS232. Various scanning pattern (i.e., line, curve, circle, spiral, etc.) can be selected with given parameters. When a warning is activated, a voice message is played that will normally require a panel touch acknowledgement. The reliability of the system is ensured in three levels: (1) hardware, (2) software real time monitoring, and (3) user. The system is currently under clinical validation.

[Study on the appropriate parameters of automatic full crown tooth preparation for dental tooth preparation robot].

PubMed

Yuan, F S; Wang, Y; Zhang, Y P; Sun, Y C; Wang, D X; Lyu, P J

2017-05-09

Objective: To further study the most suitable parameters for automatic full crown preparation using oral clinical micro robot. Its purpose is to improve the quality of automated tooth preparing for the system and to lay the foundation for clinical application. Methods: Twenty selected artificial resin teeth were used as sample teeth. The micro robot automatic tooth preparation system was used in dental clinic to control the picosecond laser beam to complete two dimensional cutting on the resin tooth sample according to the motion planning path. Using the laser scanning measuring microscope, each layer of cutting depth values was obtained and the average value was calculated. The monolayer cutting depth was determined. The three-dimensional (3D) data of the target resin teeth was obtained using internal scanner, and the CAD data of full-crown tooth preparation was designed by CAD self-develged software. According to the depth of the single layer, 11 complete resin teeth in phantom head were automatically prepared by the robot controlling the laser focused spot in accordance with the layer-cutting way. And the accuracy of resin tooth preparation was evaluated with the software. Using the same method, monolayer cutting depth parameter for cutting dental hard tissue was obtained. Then 15 extracted mandibular and maxillary first molars went through automatic full crown tooth preparation. And the 3D data of tooth preparations were obtained with intra oral scanner. The software was used to evaluate the accuracy of tooth preparation. Results: The results indicated that the single cutting depth of cutting resin teeth and in vitro teeth by picosecond laser were (60.0±2.6) and (45.0±3.6) μm, respectively. Using the tooth preparation robot, 11 artificial resin teeth and 15 complete natural teeth were automatically prepared, and the average time were (13.0±0.7), (17.0±1.8) min respectively. Through software evaluation, the average preparation depth of the occlusal surface of 11 resin teeth was approximately (2.089±0.026) mm, the error was about (0.089±0.026) mm; the average convergence angle was about 6.56°±0.30°, the error was about 0.56°±0.30°. Compared with the target preparation shape, the average shape error of the 11 resin tooth preparations was about 0.02-0.11 mm. And the average preparation depth of the occlusal surface of 15 natural teeth was approximately (2.097±0.022) mm, the error was about (0.097±0.022) mm; the average convergence angle was about 6.98°±0.35°, the error was about 0.98°±0.35°. Compared with the target preparation shape, the average shape error of the 15 natural tooth preparations was about 0.05-0.17 mm. Conclusions: The experimental results indicate that the automatic tooth preparation for resin teeth and the teeth were completed according to the specific parameters of the single cutting depth by the micro robot controlling picosecond laser respectively, its preparation accuracy met the clinical needs. And the suitability of the parameter was confirmed.

OPTICAL correlation identification technology applied in underwater laser imaging target identification

NASA Astrophysics Data System (ADS)

Yao, Guang-tao; Zhang, Xiao-hui; Ge, Wei-long

2012-01-01

The underwater laser imaging detection is an effective method of detecting short distance target underwater as an important complement of sonar detection. With the development of underwater laser imaging technology and underwater vehicle technology, the underwater automatic target identification has gotten more and more attention, and is a research difficulty in the area of underwater optical imaging information processing. Today, underwater automatic target identification based on optical imaging is usually realized with the method of digital circuit software programming. The algorithm realization and control of this method is very flexible. However, the optical imaging information is 2D image even 3D image, the amount of imaging processing information is abundant, so the electronic hardware with pure digital algorithm will need long identification time and is hard to meet the demands of real-time identification. If adopt computer parallel processing, the identification speed can be improved, but it will increase complexity, size and power consumption. This paper attempts to apply optical correlation identification technology to realize underwater automatic target identification. The optics correlation identification technology utilizes the Fourier transform characteristic of Fourier lens which can accomplish Fourier transform of image information in the level of nanosecond, and optical space interconnection calculation has the features of parallel, high speed, large capacity and high resolution, combines the flexibility of calculation and control of digital circuit method to realize optoelectronic hybrid identification mode. We reduce theoretical formulation of correlation identification and analyze the principle of optical correlation identification, and write MATLAB simulation program. We adopt single frame image obtained in underwater range gating laser imaging to identify, and through identifying and locating the different positions of target, we can improve the speed and orientation efficiency of target identification effectively, and validate the feasibility of this method primarily.

Consistent comparison of angle Kappa adjustment between Oculyzer and Topolyzer Vario topography guided LASIK for myopia by EX500 excimer laser.

PubMed

Sun, Ming-Shen; Zhang, Li; Guo, Ning; Song, Yan-Zheng; Zhang, Feng-Ju

2018-01-01

To evaluate and compare the uniformity of angle Kappa adjustment between Oculyzer and Topolyzer Vario topography guided ablation of laser in situ keratomileusis (LASIK) by EX500 excimer laser for myopia. Totally 145 cases (290 consecutive eyes )with myopia received LASIK with a target of emmetropia. The ablation for 86 cases (172 eyes) was guided manually based on Oculyzer topography (study group), while the ablation for 59 cases (118 eyes) was guided automatically by Topolyzer Vario topography (control group). Measurement of adjustment values included data respectively in horizontal and vertical direction of cornea. Horizontally, synclastic adjustment between manually actual values (dx manu ) and Oculyzer topography guided data (dx ocu ) accounts 35.5% in study group, with mean dx manu /dx ocu of 0.78±0.48; while in control group, synclastic adjustment between automatically actual values (dx auto ) and Oculyzer topography data (dx ocu ) accounts 54.2%, with mean dx auto /dx ocu of 0.79±0.66. Vertically, synclastic adjustment between dy manu and dy ocu accounts 55.2% in study group, with mean dy manu /dy ocu of 0.61±0.42; while in control group, synclastic adjustment between dy auto and dy ocu accounts 66.1%, with mean dy auto /dy ocu of 0.66±0.65. There was no statistically significant difference in ratio of actual values/Oculyzer topography guided data in horizontal and vertical direction between two groups ( P =0.951, 0.621). There is high consistency in angle Kappa adjustment guided manually by Oculyzer and guided automatically by Topolyzer Vario topography during corneal refractive surgery by WaveLight EX500 excimer laser.

Using the ultra-long pulse width pulsed dye laser and elliptical spot to treat resistant nasal telangiectasia.

PubMed

Madan, Vishal; Ferguson, Janice

2010-01-01

Thick linear telangiectasia on the ala nasi and nasolabial crease can be resistant to treatment with the potassium-titanyl-phosphate (KTP) laser and the traditional round spot on a pulsed dye laser (PDL). We evaluated the efficacy of a 3 mm x 10 mm elliptical spot using the ultra-long pulse width on a Candela Vbeam(R) PDL for treatment of PDL- and KTP laser-resistant nasal telangiectasia. Nasal telangiectasia resistant to PDL (12 patients) and KTP laser (12 patients) in 18 patients were treated with a 3 mm x 10 mm elliptical spot on the ultra-long pulse pulsed dye laser (ULPDL) utilising long pulse width [595 nm, 40 ms, double pulse, 30:20 dynamic cooling device (DCD)]. Six patients had previously received treatment with both PDL and KTP laser prior to ULPDL (40 treatments, range1-4, mean 2.2). Complete clearance was seen in ten patients, and eight patients displayed more than 80% improvement after ULPDL treatment. Self-limiting purpura occurred with round spot PDL and erythema with KTP laser and ULPDL. Subtle linear furrows along the treatment sites were seen in three patients treated with the KTP laser. ULPDL treatment delivered using a 3 mm x 10 mm elliptical spot was non-purpuric and highly effective in the treatment of nasal telangiectasia resistant to KTP laser and PDL.

Ultrasonic Ranging System With Increased Resolution

NASA Technical Reports Server (NTRS)

Meyer, William E.; Johnson, William G.

1987-01-01

Master-oscillator frequency increased. Ultrasonic range-measuring system with 0.1-in. resolution provides continuous digital display of four distance readings, each updated four times per second. Four rangefinder modules in system are modified versions of rangefinder used for automatic focusing in commercial series of cameras. Ultrasonic pulses emitted by system innocuous to both people and equipment. Provides economical solutions to such distance-measurement problems as posed by boats approaching docks, truck backing toward loading platform, runway-clearance readout for tail of airplane with high angle attack, or burglar alarm.

Automatic Recognition of Underground Targets Using Time-Frequency Analysis and Optimization Techniques

NASA Astrophysics Data System (ADS)

Gaunaurd, Guillermo C.; Strifors, Hans C.

Landmines have been laid in conflicts around the world, and they cause enormous humanitarian problems in more than 60 countries, killing, mutilating, or maiming the innocent every day. They do not differentiate between elderly, men, women, children, or animals, and they are triggered off by the victims themselves. Detection and clearance of landmines, however, have turned out to be an immensely challenging problem. A traditional means for detecting mines is the metal detector. The detector head is slowly moved over the suspicious terrain, and it gives out audible alerts when metal in the ground disturbs the magnetic field the detector generates. In general, the number of false alarms caused by various (man-made) metal objects in the ground is a great deal larger than the number of mines. This makes mine clearance a tiring task that demands the highest level of concentration. Moreover, a hazard involved is that the metal detector could be too insensitive to mines of low-metal content.

Electrical capacitance clearanceometer

NASA Technical Reports Server (NTRS)

Hester, Norbert J. (Inventor); Hornbeck, Charles E. (Inventor); Young, Joseph C. (Inventor)

1992-01-01

A hot gas turbine engine capacitive probe clearanceometer is employed to measure the clearance gap or distance between blade tips on a rotor wheel and its confining casing under operating conditions. A braze sealed tip of the probe carries a capacitor electrode which is electrically connected to an electrical inductor within the probe which is inserted into a turbine casing to position its electrode at the inner surface of the casing. Electrical power is supplied through a voltage controlled variable frequency oscillator having a tuned circuit in which the probe is a component. The oscillator signal is modulated by a change in electrical capacitance between the probe electrode and a passing blade tip surface while an automatic feedback correction circuit corrects oscillator signal drift. A change in distance between a blade tip and the probe electrode is a change in capacitance therebetween which frequency modulates the oscillator signal. The modulated oscillator signal which is then processed through a phase detector and related circuitry to provide an electrical signal is proportional to the clearance gap.

Long-term Comparison of a Large Spot Vacuum Assisted Handpiece vs the Small Spot Size Traditional Handpiece of the 800 nm Diode Laser.

PubMed

Youssef, Nour J; Rizk, Alain G; Ibrahimi, Omar A; Tannous, Zeina S

2017-09-01

BACKGROUND The 800 nm long-pulsed diode laser machine is safe and effective for permanent hair reduction. Traditionally, most long-pulsed diode lasers used for hair removal had a relatively small spot size. Recently, a long-pulsed diode laser with a large spot size and vacuum assisted suction handpiece was introduced. The treatment parameters of each type of handpiece differ. Short and long-term clinical efficacy, treatment associated pain, and patient satisfaction are important factors to be considered. This study aims to conduct a direct head to head comparison of both handpieces of the 800nm long-pulsed diode laser by evaluating long term hair reduction, treatment associated pain and patient satisfaction. Thirteen subjects were enrolled in this prospective, self-controlled, single-center study of axillary laser hair removal. The study involved 4 treatments using a long pulsed diode laser with a large spot size HS handpiece (single pass), HS handpiece (double pass), and a small spot size ET handpiece according to a randomized choice. The treatment sessions were done at 4-8 week intervals with follow up visits taken at 6 and 12 months after the last treatment session. Hair clearance and thickness analysis were assessed using macro hair count photographs taken at baseline visit, at each treatment session visit and at follow up visits. Other factors including pain, treatment duration, and patients' preference were secondary study endpoints. At 6 months follow up visits after receiving four laser treatments, there was statistically significant hair clearance in the three treatment arms with 66.1 % mean percentage hair reduction with the ET handpiece, 43.6% with the HSS (single pass) and 64.1 % with the HSD (double). However, at one year follow up, the results significantly varied from the 6 months follow up. The mean percentage hair reduction was 57.8% with the ET handpiece treated axillas (n=9), 16.5% with the HSS (single pass) handpiece treated axillas (n=7), and 46.9% with the HSD (double pass) handpiece treated axillas (n=6). Thus, at one year follow up, there was a significant hair reduction that was similar in both the ET and HSD treated axillae (57.8% and 46.9 %), but only minimal hair reduction (16.5%)was observed in the HSS treated axillae. This is the first study that compared the long-term efficacy of the ET and HS handpieces after four treatment sessions with up to 12 months follow up after the last treatment session. It is also the first study that provided head to head comparison between HS (double pass), HS (single pass), and ET handpiece taking into consideration the end hair reduction result, the time consumed, the pain score experienced, and the overall patient satisfaction. HSD had better hair clearance and patient satisfaction when compared to ET and HSS. The long term follow up results showed that ET was superior to HSS (P less than .05), but was not superior to HSD (P greater than 0.05). However, HSD treated patients had lower pain scores with HSD than with ET. We conclude that ET handpiece is almost as efficacious as HSD handpiece, and the desired end results could be achieved with HDD with better patient satisfaction, less treatment duration and less pain.

J Drugs Dermatol. 2017;16(9):893-898.

Treatment of port wine stains with pulsed dye laser: a retrospective study of 848 cases in Shandong Province, People’s Republic of China

PubMed Central

Shi, Wenhao; Wang, Jinliang; Lin, Yan; Geng, Jianhui; Wang, Haixia; Gong, Yueqin; Liu, Huaxu; Zhang, Furen

2014-01-01

Background Currently, 595 nm pulsed dye laser (PDL) therapy is offered as one of the effective treatments of port wine stains (PWSs). However, the efficacy of PDL differs in different populations. Objective The purpose of the study was to investigate the efficacy, and related factors, of 595 nm PDL in the treatment of PWSs in Chinese patients with skin type III to IV. Methods A total of 848 cases that were treated with PDL were enrolled and analyzed in this study. An independent dermatologist evaluated these lesions according to the before and after photographs. Results The response rate (RR) of all the 848 PWS patients was 69.9%, within which the cure rate was 6.3%. The patients aged ≤1 year had the highest RR (93.9%), whereas those treated after age 50 reacted the worst (RR =25%). We analyzed the anatomical distribution of the lesion and found that the temporal region had the highest lesion clearance (RR =75.3%), while the extremities had the lowest clearance (RR =44.5%). Compared with the patients whose lesion size was larger than 80 cm2, the patients with small lesion size, of 0–20 cm2, had better clinical effect (RR =73.8% vs 53.2%). The reactions of the patients with hyperplastic lesion were worse than those with red patches (RR =36.4% vs 71.7%). As well, increasing treatment numbers could achieve higher clearance rates (P=0.005). Conclusion The PDL had a relatively high RR but a low clearance rate in Chinese patients with PWS, although the earlier the intervention, the better was the efficacy. The response of PDL was, not only related to the anatomical area, but also, to the lesion size, type of lesion (ie, the presence of existing hyperplastic lesions), and the number of treatment, all of which are essential for the evaluation of therapeutic effect and acquisition of patients consent before treatment. PMID:25548515

Treatment of pigmentary disorders in patients with skin of color with a novel 755 nm picosecond, Q-switched ruby, and Q-switched Nd:YAG nanosecond lasers: A retrospective photographic review.

PubMed

Levin, Melissa Kanchanapoomi; Ng, Elise; Bae, Yoon-Soo Cindy; Brauer, Jeremy A; Geronemus, Roy G

2016-02-01

Laser procedures in skin of color (SOC) patients are challenging due to the increased risk of dyspigmentation and scarring. A novel 755 nm alexandrite picosecond laser has demonstrated effectiveness for tattoo removal and treatment of acne scars. No studies to date have evaluated its applications in pigmentary disorders. The purpose of this retrospective study was to evaluate the safety profile and efficacy of the picosecond alexandrite laser compared to the current standard treatment, Q-switched ruby and neodynium (Nd):YAG nanosecond lasers, for pigmentary disorders in SOC patients. A retrospective photographic and chart evaluation of seventy 755 nm alexandrite picosecond, ninety-two Q-switched frequency doubled 532 nm and 1,064 nm Nd:YAG nanosecond, and forty-seven Q-switched 694 nm ruby nanosecond laser treatments, in forty-two subjects of Fitzpatrick skin types III-VI was conducted in a single laser specialty center. The picosecond laser was a research prototype device. Treatment efficacy was assessed by two blinded physician evaluators, using a visual analog scale for percentage of pigmentary clearance in standard photographs. Subject assessment of efficacy, satisfaction, and adverse events was performed using a questionnaire survey. The most common pigmentary disorder treated was Nevus of Ota (38.1%), followed by solar lentigines (23.8%). Other pigmentary disorders included post-inflammatory hyperpigmentation, congenital nevus, café au lait macule, dermal melanocytosis, Nevus of Ito, and Becker's nevus. Clinical efficacy of the Q-switched nanosecond lasers and picosecond laser treatments were comparable for lesions treated on the face with a mean visual analog score of 2.57 and 2.44, respectively, corresponding to approximately 50% pigmentary clearance. Subject questionnaires were completed in 58.8% of the picosecond subjects and 52.0% of the Q-switched subjects. Eighty four percent of subjects receiving Q-switched nanosecond laser treatments and 50% of the subjects receiving alexandrite 755 nm picosecond laser treatments felt satisfied to completely satisfied. Side effects observed in subjects treated with the alexandrite 755 nm picosecond laser were similar to those commonly observed and reported with the nanosecond Q-switched technology. All side effects were temporary, resolving within one month, and no long-term complications were noted. All patients who were very satisfied with their picosecond laser treatment for Nevus of Ota noted a delayed improvement only after 3 months. The 755 nm alexandrite picosecond, 694 nm ruby, 532 nm, and 1064 nm neodynium:YAG nanosecond lasers appear to be safe and effective modalities for removal of pigmentary disorders in skin of color patients with no long-term complications if used appropriately. This study demonstrates the potential of the 755 nm alexandrite picosecond laser in further clinical applications beyond tattoo removal. While the Q-switched lasers were effective, promising results were also observed using an early version of the novel picosecond laser for the removal of pigmentary lesions in SOC patients. As we continue to improve our understanding of the 755 nm picosecond laser, this device may prove to be a safe and effective alternative to the Q-switched lasers for the treatment of facial pigmented lesions in patients with skin of color. © 2016 Wiley Periodicals, Inc.

Laser Doppler position sensor for position and shape measurements of fast rotating objects

NASA Astrophysics Data System (ADS)

Czarske, Jürgen; Pfister, Thorsten; Büttner, Lars

2006-08-01

We report about a novel optical method based on laser Doppler velocimetry for position and shape measurements of moved solid state surfaces with approximately one micrometer position resolution. 3D shape measurements of a rotating cylinder inside a turning machine as well as tip clearance measurements at a transonic centrifugal compressor performed during operation at 50,000 rpm and 586 m/s blade tip velocity are presented. All results are in good agreement with conventional reference probes. The measurement accuracy of the laser Doppler position sensor is investigated in dependence of the speckle pattern. Furthermore, it is shown that this sensor offers high temporal resolution and high position resolution simultaneously and that shading can be reduced compared to triangulation. Consequently, the presented laser Doppler position sensor opens up new perspectives in the field of real-time manufacturing metrology and process control, for example controlling the turning and the grinding process or for future developments of turbo machines.

Long-Pulsed 532-Nm Neodymium-Doped Yttrium Aluminium Garnet Laser for Treatment of Facial Plane Warts in 160 Yemeni Patients.

PubMed

Alshami, Mohammad Ali; Mohana, Mona Jameel; Alshami, Ahlam Mohammad

2016-11-01

Warts in general and plane warts in particular pose a therapeutic challenge for dermatologists. Many treatment modalities exist, with variable success rates, side effect profiles, and precautions. The long-pulsed 532-nm neodymium-doped yttrium aluminium garnet (LP Nd:YAG) laser has not been previously used for this indication. This study was conducted to assess the efficacy and safety of the LP Nd:YAG laser for treating facial plane warts. A total of 160 Yemeni patients (62 women, 98 men; age range, 5-55 years) were exposed to 1 laser treatment session with the following parameters: wavelength, 532 nm; pulse duration, 20 millisecond; spot size, 2 to 3 mm; and fluence, 25 J/cm. The end point was graying or whitening of the lesion. Color photographs were taken before and immediately after treatment and at follow-up visits 1, 4, and 16 weeks after the laser session. An overall clearance rate of 92% after only one session was achieved, with minimal and transient side effects. The LP Nd:YAG laser is safe and effective for treating facial plane warts, with a success rate of 92% after only one session.

Validation of lower limb segmental volumetry with hand-held, self-positioning three-dimensional laser scanner against water displacement.

PubMed

Mestre, Sandrine; Veye, Florent; Perez-Martin, Antonia; Behar, Thomas; Triboulet, Jean; Berron, Nicolas; Demattei, Christophe; Quéré, Isabelle

2014-01-01

Measurement of limb volume is helpful for the evaluation and follow-up of edema, especially in patients with chronic venous insufficiency (CVI) or lymphedema. Water displacement (WD) is the reference method for limb volumetry but is not really suitable for clinical routine. Indirect volumetry based on circumference measurements as well as the more expansive but automatic optoelectronic techniques do not allow detailed measurement at the extremity of the limb. We used a self-positioning laser scanner with dynamic referencing for acquisition and real-time three-dimensional (3D) reconstruction of the lower limb volume in 30 patients with CVI, 30 patients with lymphedema, and 30 healthy controls. Two independent observers performed either one or two laser scans, whose results were tested for intra- and interobserver reproducibility and compared with WD volumetry by Lin's concordance correlation coefficient and Bland and Altman graphic analysis. Automatic volume calculation from 3D laser scanning data failed in one patient with major lymphedema. Lin's concordance correlation coefficient was 0.99 and 0.98, respectively, for intraobserver no. 1 and no. 2, 0.98 for interobserver reproducibility, and 0.98 and 0.96, respectively, for observer no. 1 and observer no. 2 vs WD comparison. The 3D laser scanning yielded 1.99% precision. Accuracy was 3.12% for observer no. 1 and 2.71% for observer no. 2, laser scanning values being 90 mL higher than WD, which could be attributed to the different posture during measurement. Three-dimensional laser scanning is accurate and reproducible, and appears suitable for the evaluation of limb volume in patients with CVI or lymphedema. Copyright © 2014 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

Automatic camera to laser calibration for high accuracy mobile mapping systems using INS

NASA Astrophysics Data System (ADS)

Goeman, Werner; Douterloigne, Koen; Gautama, Sidharta

2013-09-01

A mobile mapping system (MMS) is a mobile multi-sensor platform developed by the geoinformation community to support the acquisition of huge amounts of geodata in the form of georeferenced high resolution images and dense laser clouds. Since data fusion and data integration techniques are increasingly able to combine the complementary strengths of different sensor types, the external calibration of a camera to a laser scanner is a common pre-requisite on today's mobile platforms. The methods of calibration, nevertheless, are often relatively poorly documented, are almost always time-consuming, demand expert knowledge and often require a carefully constructed calibration environment. A new methodology is studied and explored to provide a high quality external calibration for a pinhole camera to a laser scanner which is automatic, easy to perform, robust and foolproof. The method presented here, uses a portable, standard ranging pole which needs to be positioned on a known ground control point. For calibration, a well studied absolute orientation problem needs to be solved. In many cases, the camera and laser sensor are calibrated in relation to the INS system. Therefore, the transformation from camera to laser contains the cumulated error of each sensor in relation to the INS. Here, the calibration of the camera is performed in relation to the laser frame using the time synchronization between the sensors for data association. In this study, the use of the inertial relative movement will be explored to collect more useful calibration data. This results in a better intersensor calibration allowing better coloring of the clouds and a more accurate depth mask for images, especially on the edges of objects in the scene.

Remotely-interrogated high data rate free space laser communications link

DOEpatents

Ruggiero, Anthony J [Livermore, CA

2007-05-29

A system and method of remotely extracting information from a communications station by interrogation with a low power beam. Nonlinear phase conjugation of the low power beam results in a high power encoded return beam that automatically tracks the input beam and is corrected for atmospheric distortion. Intracavity nondegenerate four wave mixing is used in a broad area semiconductor laser in the communications station to produce the return beam.

Pseudo colour visualization of fused multispectral laser scattering images for optical diagnosis of rheumatoid arthritis

NASA Astrophysics Data System (ADS)

Zabarylo, U.; Minet, O.

2010-01-01

Investigations on the application of optical procedures for the diagnosis of rheumatism using scattered light images are only at the beginning both in terms of new image-processing methods and subsequent clinical application. For semi-automatic diagnosis using laser light, the multispectral scattered light images are registered and overlapped to pseudo-coloured images, which depict diagnostically essential contents by visually highlighting pathological changes.

Automatic Docking System Sensor Design, Test, and Mission Performance

NASA Technical Reports Server (NTRS)

Jackson, John L.; Howard, Richard T.; Cole, Helen J.

1998-01-01

The Video Guidance Sensor is a key element of an automatic rendezvous and docking program administered by NASA that was flown on STS-87 in November of 1997. The system used laser illumination of a passive target in the field of view of an on-board camera and processed the video image to determine the relative position and attitude between the target and the sensor. Comparisons of mission results with theoretical models and laboratory measurements will be discussed.

Acquisition of the Navy Rapid Airborne Mine Clearance System

DTIC Science & Technology

2007-04-11

will fire a supercavitating * projectile from the MH-60S helicopter using laser targeting. By supercavitating , the projectile maintains its...258 Mod 1 Armor Piercing Fin Stabilized Discarding Sabot Tracer cartridge (the Mod 1 incorporates a modified projectile nose to allow supercavitation ... Supercavitation is the use of cavitation (forcing water to move at extremely high speed) effects to create a bubble of air around the projectile, which enables

UNC Pembroke Laser Scanning Confocal Microscopy Facility

DTIC Science & Technology

2016-04-29

cultures. INVASIVE FIRE ANTS Professor Lisa Kelly of UNC Pembroke has been trained on the new confocal system. Dr. Kelly’s research...interest in the trophic ecology of the invasive fire ant has begun to benefit from the wide field view and long working distances of a confocal imaging...of protein clearance pathways in living brain tissue cultures. INVASIVE FIRE ANTS Professor Lisa Kelly of UNC Pembroke has been trained on

Randomized, Controlled Trial of Fractional Carbon Dioxide Laser Resurfacing Followed by Ultrashort Incubation Aminolevulinic Acid Blue Light Photodynamic Therapy for Actinic Keratosis.

PubMed

Alexiades, Macrene

2017-08-01

Aminolevulinic acid (ALA) photodynamic therapy (PDT) is an established treatment option for actinic keratosis (AK), and recently fractional carbon dioxide (CO2) laser was shown to improve outcomes; but studies of short incubation photosensitizer are lacking. Assess the efficacy of short incubation ALA followed by blue light PDT with and without previous fractional CO2 treatment for the treatment of AK. Randomized, paired split-design, controlled trial of fractional CO2 followed by ultrashort 15-minute versus 30-minute incubation ALA and blue light PDT for the treatment of AK on the face. The complete clearance rates (CRs) at 8 weeks after ALA PDT with and without FxCO2 at 30- and 15-minute ALA incubation times were 89.78% (+FxCO2) versus 71.20% CR (-FxCO2) at 30', and 86.38% (+FxCO2) versus 69.23% (-FxCO2) at 15' ALA incubation. All lesion improvements were statistically significant. This randomized, comparative paired group controlled clinical study demonstrates that ultrashort 15- and 30-minute incubation ALA PDTs are of limited efficacy for the treatment of AK. Pretreatment with fractional ablative resurfacing yields statistically significant greater AK clearance with ALA-PDT at ultrashort ALA incubations followed by blue light.

Theory and simulent design of a type of auto-self-protecting optical switches

NASA Astrophysics Data System (ADS)

Li, Binhong; Peng, Songcun

1990-06-01

As the use of lasers in the military and in the civilian economy increases with each passing day, it is often necessary for the human eye or sensitive instruments to observe weak lasers, such as the return waves of laser radar and laser communications signals; but it is also necessary to provide protection against damage to the eye from the strong lasers of enemy laser weapons. For this reason, it is necessary to have a kind of automatic optical self-protecting switch. Based upon a study of the transmitting and scattering characteristics of multilayer dielectric optical waveguides, a practical computer program is set up for designing a type of auto-self-protecting optical switch with a computer model by using the nonlinear property of dielectric layers and the plasma behavior of metal substrates. This technique can be used to protect the human eye and sensitive detectors from damage caused by strong laser beams.

Violence reduction and assailant control with integral laser-sighted police pistols

NASA Astrophysics Data System (ADS)

Houde-Walter, Will

1997-01-01

Laser sighting systems have been proven effective in reducing violence during tactical police operations. the laser sight plays two roles, one as an extremely intimidating pointer that informs the assailant of potential bullet placement and the other as a low light sighting device to increase the probability of hitting the target. Laser sighting gives the officer an additional alternative to lethal force. The statistical base of police data from laser assisted confrontations indicates that the assailant will capitulate, even when heavily armed, in the vast majority of cases. In this paper, we will introduce a new police technology; micro-visible diode lasers for semi- automatic piston recoil spring guide mounting of laser sights. This approach provides many advantages as the laser is concealed and protected by the pistol frame and the point of aim is aligned at the same mounting locations as the barrel. The laser can be field issues and installed or removed from the pistol in a minute with no permanent modification to the pistol.

Differential Laser Doppler based Non-Contact Sensor for Dimensional Inspection with Error Propagation Evaluation

PubMed Central

Mekid, Samir; Vacharanukul, Ketsaya

2006-01-01

To achieve dynamic error compensation in CNC machine tools, a non-contact laser probe capable of dimensional measurement of a workpiece while it is being machined has been developed and presented in this paper. The measurements are automatically fed back to the machine controller for intelligent error compensations. Based on a well resolved laser Doppler technique and real time data acquisition, the probe delivers a very promising dimensional accuracy at few microns over a range of 100 mm. The developed optical measuring apparatus employs a differential laser Doppler arrangement allowing acquisition of information from the workpiece surface. In addition, the measurements are traceable to standards of frequency allowing higher precision.

Benefits of Using Pairwise Trajectory Management in the Central East Pacific

NASA Technical Reports Server (NTRS)

Chartrand, Ryan; Ballard, Kathryn

2016-01-01

Pairwise Trajectory Management (PTM) is a concept that utilizes airborne and ground-based capabilities to enable airborne spacing operations in oceanic regions. The goal of PTM is to use enhanced surveillance, along with airborne tools, to manage the spacing between aircraft. Due to the enhanced airborne surveillance of Automatic Dependent Surveillance-Broadcast (ADS-B) information and reduced communication, the PTM minimum spacing distance will be less than distances currently required of an air traffic controller. Reduced minimum distance will increase the capacity of aircraft operations at a given altitude or volume of airspace, thereby increasing time on desired trajectory and overall flight efficiency. PTM is designed to allow a flight crew to resolve a specific traffic conflict (or conflicts), identified by the air traffic controller, while maintaining the flight crew's desired altitude. The air traffic controller issues a PTM clearance to a flight crew authorized to conduct PTM operations in order to resolve a conflict for the pair (or pairs) of aircraft (i.e., the PTM aircraft and a designated target aircraft). This clearance requires the flight crew of the PTM aircraft to use their ADS-B-enabled onboard equipment to manage their spacing relative to the designated target aircraft to ensure spacing distances that are no closer than the PTM minimum distance. When the air traffic controller determines that PTM is no longer required, the controller issues a clearance to cancel the PTM operation.

Efficacy of the Q-switched Neodymium: Yttrium Aluminum Garnet Laser in the Treatment of Blue-black Amateur and Professional Tattoos

PubMed Central

Lakshmi, Chembolli; Krishnaswamy, Gayathri

2015-01-01

Background: Q-switched neodymium: yttrium aluminum garnet (Nd: YAG) laser at a wavelength of 1064 nm primarily targets dermal melanin and black tattoo ink. Recent studies have shown that this laser is effective in treating black tattoos. There are few studies conducted in India for the same. Aim: The aim was to assess the effectiveness of Q-switched Nd: YAG laser (QSNYL) in the treatment of blue-black tattoos following 3 treatment sessions. Materials and Methods: This study, a prospective interventional study included a total of 12 blue-black tattoos. Following informed consent for the procedure, as well as for photographs, a questionnaire was administered, and improvement perceived by the patient was recorded. In addition, global assessment score (GAS) by a blinded physician was also recorded. Photographs were taken at baseline and at every follow-up. Each patient underwent three treatment sessions with 1064 nm QSNYL at 4–6 weekly intervals. Fluences ranged from 1.8 to 9 J/cm2. The follow-up was done monthly for 4 months from the first treatment session. The response was assessed by patient assessment (PA) and GAS by comparing photographs. Results: After three treatment sessions, although no patient achieved clearance, most patients showed good response with few adverse effects. An average of 64.1% (GAS) and 54.2% (PA) improvement was observed in 12 tattoos. Tattoos more than 10-year-old showed quicker clearing than those less than 10-year-old. Amateur tattoos also showed a better response in comparison to professional tattoos. Conclusion: Totally, 1064 nm QSNYL is safe and effective for lightening blue-black tattoos in pigmented Indian skin. All patients achieved near complete clearance following the continuation of treatment (an average of six sessions) although this was spaced at longer intervals. PMID:26677271

A comparative study of pulsed dye laser versus long pulsed Nd:YAG laser treatment in recalcitrant viral warts.

PubMed

Shin, Yo Sup; Cho, Eun Byul; Park, Eun Joo; Kim, Kwang Ho; Kim, Kwang Joong

2017-08-01

Viral warts are common infectious skin disease induced by human papillomavirus (HPV). But the treatment of recalcitrant warts is still challenging. In this study, we compared the effectiveness of pulsed dye laser (PDL) and long pulsed Nd:YAG (LPNY) laser in the treatment of recalcitrant viral warts. We retrospectively analyzed the medical records of patients with recalcitrant warts treated with laser therapy between January 2013 and February 2016. Seventy-two patients with recalcitrant warts were evaluated. Thirty-nine patients were treated with pulsed dye laser and thirty-three patients were treated with LPNY laser. The following parameters were used: PDL (spot size, 7 mm; pulse duration, 1.5 ms; and fluence, 10-14 J/cm 2 ) and LPNY (spot size, 5 mm; pulse duration, 20 ms; and fluence, 240-300 J/cm 2 ). Complete clearance of two patients (5.1%) in PDL group, and three patients (9.1%) in LPNY group were observed without significant side effects. The patients who achieved at least 50% improvement from baseline were 20 (51.3%) in PDL and 22 (66.7%) in LPNY, respectively. This research is meaningful because we compared the effectiveness of the PDL and LPNY in the recalcitrant warts. Both PDL and LPNY laser could be used as a safe and alternative treatment for recalcitrant warts.

Automatic Classification of Trees from Laser Scanning Point Clouds

NASA Astrophysics Data System (ADS)

Sirmacek, B.; Lindenbergh, R.

2015-08-01

Development of laser scanning technologies has promoted tree monitoring studies to a new level, as the laser scanning point clouds enable accurate 3D measurements in a fast and environmental friendly manner. In this paper, we introduce a probability matrix computation based algorithm for automatically classifying laser scanning point clouds into 'tree' and 'non-tree' classes. Our method uses the 3D coordinates of the laser scanning points as input and generates a new point cloud which holds a label for each point indicating if it belongs to the 'tree' or 'non-tree' class. To do so, a grid surface is assigned to the lowest height level of the point cloud. The grids are filled with probability values which are calculated by checking the point density above the grid. Since the tree trunk locations appear with very high values in the probability matrix, selecting the local maxima of the grid surface help to detect the tree trunks. Further points are assigned to tree trunks if they appear in the close proximity of trunks. Since heavy mathematical computations (such as point cloud organization, detailed shape 3D detection methods, graph network generation) are not required, the proposed algorithm works very fast compared to the existing methods. The tree classification results are found reliable even on point clouds of cities containing many different objects. As the most significant weakness, false detection of light poles, traffic signs and other objects close to trees cannot be prevented. Nevertheless, the experimental results on mobile and airborne laser scanning point clouds indicate the possible usage of the algorithm as an important step for tree growth observation, tree counting and similar applications. While the laser scanning point cloud is giving opportunity to classify even very small trees, accuracy of the results is reduced in the low point density areas further away than the scanning location. These advantages and disadvantages of two laser scanning point cloud sources are discussed in detail.

Crackscope : automatic pavement cracking inspection system.

DOT National Transportation Integrated Search

2008-08-01

The CrackScope system is an automated pavement crack rating system consisting of a : digital line scan camera, laser-line illuminator, and proprietary crack detection and classification : software. CrackScope is able to perform real-time pavement ins...

A Ground-Based Near Infrared Camera Array System for UAV Auto-Landing in GPS-Denied Environment.

PubMed

Yang, Tao; Li, Guangpo; Li, Jing; Zhang, Yanning; Zhang, Xiaoqiang; Zhang, Zhuoyue; Li, Zhi

2016-08-30

This paper proposes a novel infrared camera array guidance system with capability to track and provide real time position and speed of a fixed-wing Unmanned air vehicle (UAV) during a landing process. The system mainly include three novel parts: (1) Infrared camera array and near infrared laser lamp based cooperative long range optical imaging module; (2) Large scale outdoor camera array calibration module; and (3) Laser marker detection and 3D tracking module. Extensive automatic landing experiments with fixed-wing flight demonstrate that our infrared camera array system has the unique ability to guide the UAV landing safely and accurately in real time. Moreover, the measurement and control distance of our system is more than 1000 m. The experimental results also demonstrate that our system can be used for UAV automatic accurate landing in Global Position System (GPS)-denied environments.

Automatic detection of spermatozoa for laser capture microdissection.

PubMed

Vandewoestyne, Mado; Van Hoofstat, David; Van Nieuwerburgh, Filip; Deforce, Dieter

2009-03-01

In sexual assault crimes, differential extraction of spermatozoa from vaginal swab smears is often ineffective, especially when only a few spermatozoa are present in an overwhelming amount of epithelial cells. Laser capture microdissection (LCM) enables the precise separation of spermatozoa and epithelial cells. However, standard sperm-staining techniques are non-specific and rely on sperm morphology for identification. Moreover, manual screening of the microscope slides is time-consuming and labor-intensive. Here, we describe an automated screening method to detect spermatozoa stained with Sperm HY-LITER. Different ratios of spermatozoa and epithelial cells were used to assess the automatic detection method. In addition, real postcoital samples were also screened. Detected spermatozoa were isolated using LCM and DNA analysis was performed. Robust DNA profiles without allelic dropout could be obtained from as little as 30 spermatozoa recovered from postcoital samples, showing that the staining had no significant influence on DNA recovery.

Automatic Construction of 3D Basic-Semantic Models of Inhabited Interiors Using Laser Scanners and RFID Sensors

PubMed Central

Valero, Enrique; Adan, Antonio; Cerrada, Carlos

2012-01-01

This paper is focused on the automatic construction of 3D basic-semantic models of inhabited interiors using laser scanners with the help of RFID technologies. This is an innovative approach, in whose field scarce publications exist. The general strategy consists of carrying out a selective and sequential segmentation from the cloud of points by means of different algorithms which depend on the information that the RFID tags provide. The identification of basic elements of the scene, such as walls, floor, ceiling, windows, doors, tables, chairs and cabinets, and the positioning of their corresponding models can then be calculated. The fusion of both technologies thus allows a simplified 3D semantic indoor model to be obtained. This method has been tested in real scenes under difficult clutter and occlusion conditions, and has yielded promising results. PMID:22778609

Optimal and safe treatment of spider leg veins measuring less than 1.5 mm on skin type IV patients, using repeated low-fluence Nd:YAG laser pulses after polidocanol injection.

PubMed

Moreno-Moraga, Javier; Hernández, Esteban; Royo, Josefina; Alcolea, Justo; Isarría, M Jose; Pascu, Mihail Lucian; Smarandache, Adriana; Trelles, Mario

2013-05-01

Treatment of micro-veins of less than 1.5 mm with laser and with chemical sclerosis is technically challenging because of their difficulty to remedy. Laser treatment is even more difficult when dark phototypes are involved.Three groups of 30 patients each, skin type IV, and vessels measuring less than 1.5 mm in diameter, were enrolled for two treatment sessions 8 weeks apart: group A, polidocanol (POL) micro-foam injection; group B, Nd:YAG laser alone; and group C, laser after POL injection. Repeated 8-Hz low-fluence pulses, moving the hand piece over a 3-cm vein segment with an average of five laser passes maximum and with a total time irradiation of 1 s were used. Sixteen weeks after the second treatment, statistically, degree of clearance after examining photographs and patients satisfaction index, plotted on a visual analogue scale and comparing results of all three groups, results were significantly better for group C (p<0.0001). No significant differences in complications were noticed between the three groups. Efficacy of combining POL and laser proved safe and satisfactory in 96 % of patients using low-fluence laser pulses with a total cumulative energy in the 3 cm venous segment, lower than that of conventional treatment. Very few and transient complications were observed. POL foam injection followed by laser pulses is safe and efficient for vein treatment in dark-skinned patients.

Lethal photosensitization of Helicobacter species

NASA Astrophysics Data System (ADS)

Millson, Charles E.; Wilson, Michael; MacRobert, Alexander J.; Thurrell, Wendy; Mlkvy, Peter; Davies, Claire; Bown, Stephen G.

1995-01-01

Helicobacter pylori (H. pylori) is associated with a large number of gastroduodenal disorders. Clearance of the bacteria has been shown to benefit patients with duodenal ulcers, gastric ulcers, and certain rare types of gastric tumors. Broad-spectrum antibiotics are the mainstay of current treatment strategies but side-effects, poor compliance, and drug resistance limit their usefulness. We sensitized H. pylori with toluidine blue, haematoporphyrin derivative, aluminum disulphonated phthalocyanine, methylene blue or protoporphyrin IX prior to exposure to low-power laser light from either a gallium aluminum arsenide laser or a helium neon gas laser. All 5 sensitizers caused reductions of greater than 1000-fold in the number of viable bacteria. Light alone had no effect and only HpD caused a significant decrease in bacterial numbers without laser light. Next, we sensitized H. mustelae on explanted ferret gastric mucosa (ex vivo) with the same sensitizers and exposed them to light from a copper vapor pumped dye laser tuned appropriately. MB caused significant reductions in bacterial counts. Successful lethal photosensitization of Helicobacter pylori both in vitro and ex vivo raises the possibility of a local method for eradicating the bacteria, especially as the bacteria are only found in those parts of the upper gastrointestinal tract that are accessible to the endoscope.

Dynamic in vivo imaging of small animal brain using pulsed laser diode-based photoacoustic tomography system

NASA Astrophysics Data System (ADS)

Upputuri, Paul Kumar; Pramanik, Manojit

2017-09-01

We demonstrate dynamic in vivo imaging using a low-cost portable pulsed laser diode (PLD)-based photoacoustic tomography system. The system takes advantage of an 803-nm PLD having high-repetition rate ˜7000 Hz combined with a fast-scanning single-element ultrasound transducer leading to a 5 s cross-sectional imaging. Cortical vasculature is imaged in scan time of 5 s with high signal-to-noise ratio ˜48. To examine the ability for dynamic imaging, we monitored the fast uptake and clearance process of indocyanine green in the rat brain. The system will find applications to study neurofunctional activities, characterization of pharmacokinetic, and biodistribution profiles in the development process of drugs or imaging agents.

Estimation of Tree Position and STEM Diameter Using Simultaneous Localization and Mapping with Data from a Backpack-Mounted Laser Scanner

NASA Astrophysics Data System (ADS)

Holmgren, J.; Tulldahl, H. M.; Nordlöf, J.; Nyström, M.; Olofsson, K.; Rydell, J.; Willén, E.

2017-10-01

A system was developed for automatic estimations of tree positions and stem diameters. The sensor trajectory was first estimated using a positioning system that consists of a low precision inertial measurement unit supported by image matching with data from a stereo-camera. The initial estimation of the sensor trajectory was then calibrated by adjustments of the sensor pose using the laser scanner data. Special features suitable for forest environments were used to solve the correspondence and matching problems. Tree stem diameters were estimated for stem sections using laser data from individual scanner rotations and were then used for calibration of the sensor pose. A segmentation algorithm was used to associate stem sections to individual tree stems. The stem diameter estimates of all stem sections associated to the same tree stem were then combined for estimation of stem diameter at breast height (DBH). The system was validated on four 20 m radius circular plots and manual measured trees were automatically linked to trees detected in laser data. The DBH could be estimated with a RMSE of 19 mm (6 %) and a bias of 8 mm (3 %). The calibrated sensor trajectory and the combined use of circle fits from individual scanner rotations made it possible to obtain reliable DBH estimates also with a low precision positioning system.

New progress of ranging technology at Wuhan Satellite Laser Ranging Station

NASA Technical Reports Server (NTRS)

Xia, Zhiz-Hong; Ye, Wen-Wei; Cai, Qing-Fu

1993-01-01

A satellite laser ranging system with an accuracy of the level of centimeter has been successfully developed at the Institute of Seismology, State Seismological Bureau with the cooperation of the Institute of Geodesy and Geophysics, Chinese Academy of Science. With significant improvements on the base of the second generation SLR system developed in 1985, ranging accuracy of the new system has been upgraded from 15 cm to 3-4 cm. Measuring range has also been expanded, so that the ETALON satellite with an orbit height of 20,000 km launched by the former U.S.S.R. can now be tracked. Compared with the 2nd generation SLR system, the newly developed system has the following improvements. A Q modulated laser is replaced by a mode-locked YAG laser. The new device has a pulse width of 150 ps and a repetition rate of 1-4 pps. A quick response photomultiplier has been adopted as the receiver for echo; for example, the adoption of the MCP tube has obviously reduced the jitter error of the transit time and has improved the ranging accuracy. The whole system is controlled by an IBM PC/XT Computer to guide automatic tracking and measurement. It can carry out these functions for satellite orbit calculation, real-time tracking and adjusting, data acquisition and the preprocessed of observing data, etc. The automatization level and reliability of the observation have obviously improved.

In-situ position and vibration measurement of rough surfaces using laser Doppler distance sensors

NASA Astrophysics Data System (ADS)

Czarske, J.; Pfister, T.; Günther, P.; Büttner, L.

2009-06-01

In-situ measurement of distances and shapes as well as dynamic deformations and vibrations of fast moving and especially rotating objects, such as gear shafts and turbine blades, is an important task at process control. We recently developed a laser Doppler distance frequency sensor, employing two superposed fan-shaped interference fringe systems with contrary fringe spacing gradients. Via two Doppler frequency evaluations the non-incremental position (i.e. distance) and the tangential velocity of rotating bodies are determined simultaneously. The distance uncertainty is in contrast to e.g. triangulation in principle independent of the object velocity. This unique feature allows micrometer resolutions of fast moved rough surfaces. The novel sensor was applied at turbo machines in order to control the tip clearance. The measurements at a transonic centrifugal compressor were performed during operation at up to 50,000 rpm, i.e. 586 m/s velocity of the blade tips. Due to the operational conditions such as temperatures of up to 300 °C, a flexible and robust measurement system with a passive fiber-coupled sensor, using diffractive optics, has been realized. Since the tip clearance of individual blades could be temporally resolved an analysis of blade vibrations was possible. A Fourier transformation of the blade distances results in an average period of 3 revolutions corresponding to a frequency of 1/3 of the rotary frequency. Additionally, a laser Doppler distance sensor using two tilted fringe systems and phase evaluation will be presented. This phase sensor exhibits a minimum position resolution of σz = 140 nm. It allows precise in-situ shape measurements at grinding and turning processes.

Treatment of resistant port wine stains (PWS) with pulsed dye laser and non-contact vacuum: a pilot study.

PubMed

Kautz, Gerd; Kautz, Ingrid; Segal, Jenny; Zehren, Sabrina

2010-07-01

The blanching of resistant port wine stains (PWS) with a pulsed dye laser (PDL) requires a large number of treatments, resulting in substantial discomfort to patients, many of them children. Pneumatic skin flattening (PSF - Serenity Pro) is a new technology that generates a vacuum over the skin and reduces pain in laser-based treatments of the skin, while creating contact between the skin and an upper window. The same technology can be utilized to increase skin blood fraction while operated in a non-contact mode. The objective of this study was to test the enhancement in the efficacy of PWS treatment with PDL and Serenity Pro while vacuum is being utilized in the non-contact, blood-enrichment mode. Fifteen patients with resistant PWS underwent 1-4 treatments (interval of 5-20 weeks) under general anesthesia with a 595-nm PDL at 10-14 J/cm(2), 1.5-3 ms pulse duration, and 7-mm spot size. Lesion blanching with DCD chilling and with vacuum were photographed and compared. Better blanching of various degrees was observed on resistant PWS with the blood-enrichment technique in seven out of 11 patients who returned for follow-up. There were no cases of decrease in efficacy. Blood enrichment with the Serenity Pro non-contact vacuum technology has the potential of enhancing the capability of treating resistant port wine stains in over 50% of cases. Further studies will better quantify the number of treatments necessary for better lesion clearance. The vacuum-assisted technique may be of particular importance in view of the fact that achieving complete lesion clearance remains a challenge in PWS treatments.

Determination of the human spine curve based on laser triangulation.

PubMed

Poredoš, Primož; Čelan, Dušan; Možina, Janez; Jezeršek, Matija

2015-02-05

The main objective of the present method was to automatically obtain a spatial curve of the thoracic and lumbar spine based on a 3D shape measurement of a human torso with developed scoliosis. Manual determination of the spine curve, which was based on palpation of the thoracic and lumbar spinous processes, was found to be an appropriate way to validate the method. Therefore a new, noninvasive, optical 3D method for human torso evaluation in medical practice is introduced. Twenty-four patients with confirmed clinical diagnosis of scoliosis were scanned using a specially developed 3D laser profilometer. The measuring principle of the system is based on laser triangulation with one-laser-plane illumination. The measurement took approximately 10 seconds at 700 mm of the longitudinal translation along the back. The single point measurement accuracy was 0.1 mm. Computer analysis of the measured surface returned two 3D curves. The first curve was determined by manual marking (manual curve), and the second was determined by detecting surface curvature extremes (automatic curve). The manual and automatic curve comparison was given as the root mean square deviation (RMSD) for each patient. The intra-operator study involved assessing 20 successive measurements of the same person, and the inter-operator study involved assessing measurements from 8 operators. The results obtained for the 24 patients showed that the typical RMSD between the manual and automatic curve was 5.0 mm in the frontal plane and 1.0 mm in the sagittal plane, which is a good result compared with palpatory accuracy (9.8 mm). The intra-operator repeatability of the presented method in the frontal and sagittal planes was 0.45 mm and 0.06 mm, respectively. The inter-operator repeatability assessment shows that that the presented method is invariant to the operator of the computer program with the presented method. The main novelty of the presented paper is the development of a new, non-contact method that provides a quick, precise and non-invasive way to determine the spatial spine curve for patients with developed scoliosis and the validation of the presented method using the palpation of the spinous processes, where no harmful ionizing radiation is present.

Monitoring sodium removal and delivered dialysis by conductivity.

PubMed

Locatelli, F; Di Filippo, S; Manzoni, C; Corti, M; Andrulli, S; Pontoriero, G

1995-11-01

As cardiovascular stability and the delivery of the prescribed dialysis "dose" seem to be the main factors in determining the morbidity and mortality of hemodialyzer patients today, it is of paramount importance to match hydro-sodium removal with interdialytic load and to verify the delivered dialysis at each session. A specially designed Biofeedback Module (BM--COT Hospal) allows the automatic determination of plasma water conductivity and effective ionic dialysance with no need for blood samples. Using BM, we evaluated the validity of "conductivity kinetic modelling" (CKM) and the possibility that this may substitute "sodium kinetic modelling". Moreover, we evaluated the "in vivo" relationship between ionic dialysance and effective urea clearance. Our results demonstrate that: 1) CKM makes it possible to obtain programmed end-dialysis plasma water conductivity with an error of less than +/- 0.14 mS/cm, roughly equivalent to a sodium concentration of +/- 1.4 mEq/L. 2). Ionic dialysance and effective urea clearance are not equivalent but, as the interrelationship between these is known, the BM allows the routine monitoring of delivered dialysis.

Laser Scanning In Inspection

NASA Astrophysics Data System (ADS)

West, Patricia; Baker, Lionel R.

1989-03-01

This paper is a review of the applications of laser scanning in inspection. The reasons for the choice of a laser in flying spot scanning and the optical properties of a laser beam which are of value in a scanning instrument will be given. The many methods of scanning laser beams in both one and two dimensions will be described. The use of one dimensional laser scanners for automatic surface inspection for transmitting and reflective products will be covered in detail, with particular emphasis on light collection techniques. On-line inspection applications which will be mentioned include: photographic film web, metal strip products, paper web, glass sheet, car body paint surfaces and internal cylinder bores. Two dimensional laser scanning is employed in applications where increased resolution, increased depth of focus, and better contrast are required compared with conventional vidicon TV or solid state array cameras. Such examples as special microscope laser scanning systems and a TV compatible system for use in restricted areas of a nuclear reactor will be described. The technical and economic benefits and limitations of laser scanning video systems will be compared with conventional TV and CCD array devices.

A low-fluence 1064-nm Q-switched neodymium-doped yttrium aluminium garnet laser for the treatment of café-au-lait macules.

PubMed

Kim, Hyeong-Rae; Ha, Jeong-Min; Park, Min-Soo; Lee, Young; Seo, Young-Joon; Kim, Chang-Deok; Lee, Jeung-Hoon; Im, Myung

2015-09-01

Café-au-lait macules (CALMs) are a common pigmentary disorder. Although a variety of laser modalities have been used to treat CALMs, their efficacies vary and dyspigmentation may develop. We evaluated the clinical efficacy and safety of a low-fluence 1064-nm Q-switched neodymium-doped yttrium aluminium garnet (Nd:YAG) laser for the treatment of CALMs. In a preliminary investigation, 6 patients underwent a split-lesion comparative study with 532- and 1064-nm Q-switched Nd:YAG laser treatment. In total, 32 patients with 39 CALMs were enrolled in a subsequent prospective trial to evaluate the treatment with a low-fluence 1064-nm Q-switched Nd:YAG laser. In the preliminary study, the 1064-nm treatment group had a more favorable response and a shorter recovery time. In a subsequent prospective trial of a 1064-nm laser, 74.4% of the lesions showed a clinical response with clearance of ≥50.0%. The treatment regimen was well tolerated; 15.4% of patients experienced adverse events. The study participants were followed for 6 months, and there were no relevant treatment controls in the prospective trial group. Low-fluence 1064-nm Q-switched Nd:YAG laser therapy afforded good clinical improvement for treating CALMs. Copyright © 2015 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.

Strategies for registering range images from unknown camera positions

NASA Astrophysics Data System (ADS)

Bernardini, Fausto; Rushmeier, Holly E.

2000-03-01

We describe a project to construct a 3D numerical model of Michelangelo's Florentine Pieta to be used in a study of the sculpture. Here we focus on the registration of the range images used to construct the model. The major challenge was the range of length scales involved. A resolution of 1 mm or less required for the 2.25 m tall piece. To achieve this resolution, we could only acquire an area of 20 by 20 cm per scan. A total of approximately 700 images were required. Ideally, a tracker would be attached to the scanner to record position and pose. The use of a tracker was not possible in the field. Instead, we used a crude-to-fine approach to registering the meshes to one another. The crudest level consisted of pairwise manual registration, aided by texture maps containing laser dots that were projected onto the sculpture. This crude alignment was refined by an automatic registration of laser dot centers. In this phase, we found that consistency constraints on dot matches were essential to obtaining accurate results. The laser dot alignment was refined by an automatic registration of laser dot centers. In this phase, we found that consistency constraints on dot matches were essential to obtaining accurate results. The laser dot alignment was further refined using a variation of the ICP algorithm developed by Besl and McKay. In the application of ICP to global registration, we developed a method to avoid one class of local minima by finding a set of points, rather than the single point, that matches each candidate point.

A 3D Laser Profiling System for Rail Surface Defect Detection

PubMed Central

Li, Qingquan; Mao, Qingzhou; Zou, Qin

2017-01-01

Rail surface defects such as the abrasion, scratch and peeling often cause damages to the train wheels and rail bearings. An efficient and accurate detection of rail defects is of vital importance for the safety of railway transportation. In the past few decades, automatic rail defect detection has been studied; however, most developed methods use optic-imaging techniques to collect the rail surface data and are still suffering from a high false recognition rate. In this paper, a novel 3D laser profiling system (3D-LPS) is proposed, which integrates a laser scanner, odometer, inertial measurement unit (IMU) and global position system (GPS) to capture the rail surface profile data. For automatic defect detection, first, the deviation between the measured profile and a standard rail model profile is computed for each laser-imaging profile, and the points with large deviations are marked as candidate defect points. Specifically, an adaptive iterative closest point (AICP) algorithm is proposed to register the point sets of the measured profile with the standard rail model profile, and the registration precision is improved to the sub-millimeter level. Second, all of the measured profiles are combined together to form the rail surface through a high-precision positioning process with the IMU, odometer and GPS data. Third, the candidate defect points are merged into candidate defect regions using the K-means clustering. At last, the candidate defect regions are classified by a decision tree classifier. Experimental results demonstrate the effectiveness of the proposed laser-profiling system in rail surface defect detection and classification. PMID:28777323

Automatic low-order aberration compensator for solid-state slab lasers

NASA Astrophysics Data System (ADS)

Yu, Xin; Dong, Lizhi; Lai, Boheng; Yang, Ping; Kong, Qingfeng; Yang, Kangjian; Liu, Yong; Tang, Guomao; Xu, Bing

2016-09-01

Slab geometry is a promising architecture for power scaling of solid-state lasers. By propagating the laser beams along zigzag path in the gain medium, the thermal effects can be well compensated. However, in the non-zigzag direction, the thermal effects are not compensated. Among the overall aberrations in the slab lasers, the major contributors are two low-order aberrations: astigmatism and defocus, which can range up to over 100 microns (peak to valley), leading to detracted beam quality. Another problem with slab lasers is that the output beams are generally in a rectangular aperture with high aspect ratio (normally 1:10), where square beams are favorable for many applications. In order to solve these problems, we propose an automatic low-order aberration compensation system. This system is composed of three lenses fixed on a motorized rail, one is a spherical lens and the others are cylindrical lenses. Astigmatism and defocus can be compensated by merely adjusting the distances between the lenses. Two wave-front sensors are employed in this compensation system, one is used for detecting the initial parameters of the beams, and the other one is used for detecting the remaining aberrations after correction. The adjustments of the three lenses are directly calculated based on beam parameters using ray tracing method. The initial size of the beam is 3.2mm by 26mm, and peak to valley(PV) value of the wave-front is 33.07λ(λ=1064nm). After correction, the dimension becomes 40mm by 40mm, and peak to valley (PV) value of the wave-front is less than 2 microns.

Precision targeting with a tracking adaptive optics scanning laser ophthalmoscope

NASA Astrophysics Data System (ADS)

Hammer, Daniel X.; Ferguson, R. Daniel; Bigelow, Chad E.; Iftimia, Nicusor V.; Ustun, Teoman E.; Noojin, Gary D.; Stolarski, David J.; Hodnett, Harvey M.; Imholte, Michelle L.; Kumru, Semih S.; McCall, Michelle N.; Toth, Cynthia A.; Rockwell, Benjamin A.

2006-02-01

Precise targeting of retinal structures including retinal pigment epithelial cells, feeder vessels, ganglion cells, photoreceptors, and other cells important for light transduction may enable earlier disease intervention with laser therapies and advanced methods for vision studies. A novel imaging system based upon scanning laser ophthalmoscopy (SLO) with adaptive optics (AO) and active image stabilization was designed, developed, and tested in humans and animals. An additional port allows delivery of aberration-corrected therapeutic/stimulus laser sources. The system design includes simultaneous presentation of non-AO, wide-field (~40 deg) and AO, high-magnification (1-2 deg) retinal scans easily positioned anywhere on the retina in a drag-and-drop manner. The AO optical design achieves an error of <0.45 waves (at 800 nm) over +/-6 deg on the retina. A MEMS-based deformable mirror (Boston Micromachines Inc.) is used for wave-front correction. The third generation retinal tracking system achieves a bandwidth of greater than 1 kHz allowing acquisition of stabilized AO images with an accuracy of ~10 μm. Normal adult human volunteers and animals with previously-placed lesions (cynomolgus monkeys) were tested to optimize the tracking instrumentation and to characterize AO imaging performance. Ultrafast laser pulses were delivered to monkeys to characterize the ability to precisely place lesions and stimulus beams. Other advanced features such as real-time image averaging, automatic highresolution mosaic generation, and automatic blink detection and tracking re-lock were also tested. The system has the potential to become an important tool to clinicians and researchers for early detection and treatment of retinal diseases.

Self-aligned spatial filtering using laser optical tweezers.

PubMed

Birkbeck, Aaron L; Zlatanovic, Sanja; Esener, Sadik C

2006-09-01

We present an optical spatial filtering device that has been integrated into a microfluidic system and whose motion and alignment is controlled using a laser optical tweezer. The lithographically patterned micro-optical spatial filter device filters out higher frequency additive noise components by automatically aligning itself in three dimensions to the focus of the laser beam. This self-alignment capability is achieved through the attachment of a refractive optical element directly over the circular aperture or pinhole of the spatial filter. A discussion of two different spatial filter designs is presented along with experimental results that demonstrate the effectiveness of the self-aligned micro-optic spatial filter.

Stabilizing operation point technique based on the tunable distributed feedback laser for interferometric sensors

NASA Astrophysics Data System (ADS)

Mao, Xuefeng; Zhou, Xinlei; Yu, Qingxu

2016-02-01

We describe a stabilizing operation point technique based on the tunable Distributed Feedback (DFB) laser for quadrature demodulation of interferometric sensors. By introducing automatic lock quadrature point and wavelength periodically tuning compensation into an interferometric system, the operation point of interferometric system is stabilized when the system suffers various environmental perturbations. To demonstrate the feasibility of this stabilizing operation point technique, experiments have been performed using a tunable-DFB-laser as light source to interrogate an extrinsic Fabry-Perot interferometric vibration sensor and a diaphragm-based acoustic sensor. Experimental results show that good tracing of Q-point was effectively realized.

Carbachol-induced fluid movement through methazolamide-sensitive bicarbonate production in rat parotid intralobular ducts: quantitative analysis of fluorescence images using fluorescent dye sulforhodamine under a confocal laser scanning microscope.

PubMed

Nakamoto, Tetsuji; Shiba, Yoshiki; Hirono, Chikara; Sugita, Makoto; Takemoto, Kazuhisa; Iwasa, Yoshiko; Akagawa, Yasumasa

2002-09-01

Fluid secretion is observed at the openings of ducts in the exocrine gland. It remains unclear whether the ducts are involved in fluid secretion in the salivary glands. In the present study, we investigated the exclusion of fluorescent dye from the duct lumen by carbachol (CCh) in isolated parotid intralobular duct segments to clarify the ability of the ducts for the fluid secretion. When the membrane-impermeable fluorescent dye, sulforhodamine, was added to the superfused extracellular solution, quantitative fluorescence images of the duct lumen were obtained under the optical sectioning at the level of the duct lumen using a confocal laser scanning microscope. CCh decreased the fluorescent intensity in the duct lumen during the superfusion of the fluorescent dye, and CCh flushed out small viscous substances stained with the fluorescent dye from isolated duct lumen, suggesting that CCh might induce fluid secretion in the duct, leading to the clearance of the dye and small stained clumps from the duct lumen. CCh-induced clearance of the fluorescent dye was divided into two phases by the sensitivity to external Ca2+ and methazolamide, an inhibitor for carbonic anhydrase. The initial phase was insensitive to these, and the subsequent late phase was sensitive to these. A major portion in the late phase was inhibited by removal of bicarbonate in the superfusion solution and DPC, but not low concentration of external Cl-, bumetanide or DIDS, suggesting that methazolamide-sensitive production of HCO3-, but not the Cl- uptake mechanism, might contribute to the CCh-induced clearance of the dye from the duct lumen. These results represent the first measurements of fluid movement in isolated duct segments, and suggest that carbachol might evoke fluid secretion possibly through Ca2+-activated, DPC-sensitive anion channels with HCO3- secretion in the rat parotid intralobular ducts.

A Spherical Electro Optic High Voltage Sensor

DTIC Science & Technology

1989-06-01

electro - optic (EO) crystal is introduced for photonic measurement of pulsed high-voltage fields. A spherical shape is used in order to reduce electric field gradients in the vicinity of the sensor. The sensor is pure dielectric and is interrogated remotely using a laser. The sensor does not require the connection of any conducting components, which results in the highest electrical isolation. The spherical nature of the crystal coupled with the incident laser beam, and crossed polarizers (intensity modulation scheme). automatically produces interference figures. The

Hybrid tracking and control system for computer-aided retinal surgery

NASA Astrophysics Data System (ADS)

Ferguson, R. D.; Wright, Cameron H. G.; Rylander, Henry G., III; Welch, Ashley J.; Barrett, Steven F.

1996-05-01

We describe initial experimental results of a new hybrid digital and analog design for retinal tracking and laser beam control. Initial results demonstrate tracking rates which exceed the equivalent of 50 degrees per second in the eye, with automatic lesion pattern creation and robust loss of lock detection. Robotically assisted laser surgery to treat conditions such as diabetic retinopathy, macular degeneration, and retinal tears can now be realized under clinical conditions with requisite safety using standard video hardware and inexpensive optical components.

Array Automated Assembly Task Low Cost Silicon Solar Array Project, Phase 2

NASA Technical Reports Server (NTRS)

Rhee, S. S.; Jones, G. T.; Allison, K. L.

1978-01-01

Progress in the development of solar cells and module process steps for low-cost solar arrays is reported. Specific topics covered include: (1) a system to automatically measure solar cell electrical performance parameters; (2) automation of wafer surface preparation, printing, and plating; (3) laser inspection of mechanical defects of solar cells; and (4) a silicon antireflection coating system. Two solar cell process steps, laser trimming and holing automation and spray-on dopant junction formation, are described.

CFD simulation of a screw compressor including leakage flows and rotor heating

NASA Astrophysics Data System (ADS)

Spille-Kohoff, Andreas, Dr.; Hesse, Jan; El Shorbagy, Ahmed

2015-08-01

Computational Fluid Dynamics (CFD) simulations have promising potential to become an important part in the development process of positive displacement (PD) machines. CFD delivers deep insights into the flow and thermodynamic behaviour of PD machines. However, the numerical simulation of such machines is more complex compared to dynamic pumps like turbines or fans. The fluid transport in size-changing chambers with very small clearances between the rotors, and between rotors and casing, demands complex meshes that change with each time step. Additionally, the losses due to leakage flows and the heat transfer to the rotors need high-quality meshes so that automatic remeshing is almost impossible. In this paper, setup steps and results for the simulation of a dry screw compressor are shown. The rotating parts are meshed with TwinMesh, a special hexahedral meshing program for gear pumps, gerotors, lobe pumps and screw compressors. In particular, these meshes include axial and radial clearances between housing and rotors, and beside the fluid volume the rotor solids are also meshed. The CFD simulation accounts for gas flow with compressibility and turbulence effects, heat transfer between gas and rotors, and leakage flows through the clearances. We show time- resolved results for torques, forces, interlobe pressure, mass flow, and heat flow between gas and rotors, as well as time- and space-resolved results for pressure, velocity, temperature etc. for different discharge ports and working points of the screw compressor. These results are also used as thermal loads for deformation simulations of the rotors.

Automatic readout micrometer

DOEpatents

Lauritzen, Ted

1982-01-01

A measuring system is disclosed for surveying and very accurately positioning objects with respect to a reference line. A principal use of this surveying system is for accurately aligning the electromagnets which direct a particle beam emitted from a particle accelerator. Prior art surveying systems require highly skilled surveyors. Prior art systems include, for example, optical surveying systems which are susceptible to operator reading errors, and celestial navigation-type surveying systems, with their inherent complexities. The present invention provides an automatic readout micrometer which can very accurately measure distances. The invention has a simplicity of operation which practically eliminates the possibilities of operator optical reading error, owning to the elimination of traditional optical alignments for making measurements. The invention has an extendable arm which carries a laser surveying target. The extendable arm can be continuously positioned over its entire length of travel by either a coarse or fine adjustment without having the fine adjustment outrun the coarse adjustment until a reference laser beam is centered on the target as indicated by a digital readout. The length of the micrometer can then be accurately and automatically read by a computer and compared with a standardized set of alignment measurements. Due to its construction, the micrometer eliminates any errors due to temperature changes when the system is operated within a standard operating temperature range.

Automatic readout micrometer

DOEpatents

Lauritzen, T.

A measuring system is described for surveying and very accurately positioning objects with respect to a reference line. A principle use of this surveying system is for accurately aligning the electromagnets which direct a particle beam emitted from a particle accelerator. Prior art surveying systems require highly skilled surveyors. Prior art systems include, for example, optical surveying systems which are susceptible to operator reading errors, and celestial navigation-type surveying systems, with their inherent complexities. The present invention provides an automatic readout micrometer which can very accurately measure distances. The invention has a simplicity of operation which practically eliminates the possibilities of operator optical reading error, owning to the elimination of traditional optical alignments for making measurements. The invention has an extendable arm which carries a laser surveying target. The extendable arm can be continuously positioned over its entire length of travel by either a coarse of fine adjustment without having the fine adjustment outrun the coarse adjustment until a reference laser beam is centered on the target as indicated by a digital readout. The length of the micrometer can then be accurately and automatically read by a computer and compared with a standardized set of alignment measurements. Due to its construction, the micrometer eliminates any errors due to temperature changes when the system is operated within a standard operating temperature range.

Cell optoporation with a sub-15 fs and a 250-fs laser

NASA Astrophysics Data System (ADS)

Breunig, Hans Georg; Batista, Ana; Uchugonova, Aisada; König, Karsten

2016-06-01

We employed two commercially available femtosecond lasers, a Ti:sapphire and a ytterbium-based oscillator, to directly compare from a user's practical point-of-view in one common experimental setup the efficiencies of transient laser-induced cell membrane permeabilization, i.e., of so-called optoporation. The experimental setup consisted of a modified multiphoton laser-scanning microscope employing high-NA focusing optics. An automatic cell irradiation procedure was realized with custom-made software that identified cell positions and controlled relevant hardware components. The Ti:sapphire and ytterbium-based oscillators generated broadband sub-15-fs pulses around 800 nm and 250-fs pulses at 1044 nm, respectively. A higher optoporation rate and posttreatment viability were observed for the shorter fs pulses, confirming the importance of multiphoton effects for efficient optoporation.

Equipment and New Products

ERIC Educational Resources Information Center

Poitras, Adrian W., Ed.

1973-01-01

The following items are discussed: Digital Counters and Readout Devices, Automatic Burette Outfits, Noise Exposure System, Helium-Cadmium Laser, New pH Buffers and Flip-Top Dispenser, Voltage Calibrator Transfer Standard, Photomicrographic Stereo Zoom Microscope, Portable pH Meter, Micromanipulators, The Snuffer, Electronic Top-Loading Balances,…

Automated survey of pavement distress based on 2D and 3D laser images.

DOT National Transportation Integrated Search

2011-11-01

Despite numerous efforts in recent decades, currently most information on pavement surface distresses cannot be obtained automatically, at high-speed, and at acceptable precision and bias levels. This research provided seed funding to produce a funct...

High-efficency stable 213-nm generation for LASIK application

NASA Astrophysics Data System (ADS)

Wang, Zhenglin; Alameh, Kamal; Zheng, Rong

2005-01-01

213nm Solid-state laser technology provides an alternative method to replace toxic excimer laser in LASIK system. In this paper, we report a compact fifth harmonic generation system to generate high pulse energy 213nm laser from Q-switched Nd:YAG laser for LASIK application based on three stages harmonic generation procedures. A novel crystal housing was specifically designed to hold the three crystals with each crystal has independent, precise angular adjustment structure and automatic tuning control. The crystal temperature is well maintained at ~130°C to improve harmonic generation stability and crystal operation lifetime. An output pulse energy 35mJ is obtained at 213nm, corresponding to total conversion efficiency ~10% from 1064nm pump laser. In system verification tests, the 213nm output power drops less than 5% after 5 millions pulse shots and no significant damage appears in the crystals.

Laser megajoule 1.06-μm mirror production with very high laser damage threshold

NASA Astrophysics Data System (ADS)

Pinot, B.; Leplan, Herve; Houbre, Francois; Lavastre, Eric; Poncetta, Jean-Christophe; Chabassier, Genevieve

2002-03-01

As part of the LMJ (Laser Megajoule) program, CEA is building the LIL laser with full size optics and LMJ requirements. SAGEM has been selected as the supplier of large optical components and coatings with very high laser- induced damage threshold. Including spare parts, about 100 mirrors 610*430 mm2 with LIDT-3ns>25 J/cm2 have to be produced. Using a 5 m3 vacuum chamber and the 100 J/cm2 mirror coating process developed at CEA-LETI, with Hafnium and SiO2 materials, we are now typically in a serial production phase. To date, about thirty mirrors have been delivered. This paper focuses on the acceptance tests performed after coating, at SAGEM then CEA: LIDT measurement and Raster-Scan on samples; reflectance mapping on CEA automatic photometer; reflected wavefront deformation with \

Turbulence measurements of high shear flow fields in a turbomachine seal configuration

NASA Technical Reports Server (NTRS)

Morrison, Gerald L.; Deotte, Robert E., Jr.; Thames, H. Davis, III.

1992-01-01

The mean velocity and Reynolds stress tensor throughout a whirling annular seal are presented. The data was collected with a three dimensional laser Doppler velocimeter using phase averaging. Two axial flow conditions (Re = 12,000 and 24,000) were studied at one shaft speed (Ta = 6,600). The eccentricity and whirl ratios were 50 and 100 percent, respectively. There is a region of high axial momentum in this region is higher in the low Reynolds number case due to an axial recirculation zone that occurs on the suction side of the rotor at the inlet. The recirculation zone does not occur in the high Reynolds number case. At both Reynolds numbers, there is a recirculation zone on the rotor surface in the pressure side of the inlet. This recirculation zone extends from 20 to 200 degrees rotor zenith in the tangential direction, and is one third of a clearance wide radially. The high Reynolds number recirculation zone is 1.5 mean clearances long, while the low Reynolds number zone extends 2 mean clearances downstream. When compared to previous studies, it is apparent that the tangential momentum is no greater for a seal with whirl than for one without if other parameters are constant. Areas of high tangential momentum occur in the clearance where the axial momentum is low. Average exit plane tangential velocities in the high Reynolds number case are 1.5 times greater than those in the other flow case. These results are in general agreement with predictions made by other investigators.

Solenoid for Laser Induced Plasma Experiments at Janus

NASA Astrophysics Data System (ADS)

Klein, Sallee; Leferve, Heath; Kemp, Gregory; Mariscal, Derek; Rasmus, Alex; Williams, Jackson; Gillespie, Robb; Manuel, Mario; Kuranz, Carolyn; Keiter, Paul; Drake, R.

2017-10-01

Creating invariant magnetic fields for experiments involving laser induced plasmas is particularly challenging due to the high voltages at which the solenoid must be pulsed. Creating a solenoid resilient enough to survive through large numbers of voltage discharges, enabling it to endure a campaign lasting several weeks, is exceptionally difficult. Here we present a solenoid that is robust through 40 μs pulses at a 13 kV potential. This solenoid is a vast improvement over our previously fielded designs in peak magnetic field capabilities and robustness. Designed to be operated at small-scale laser facilities, the solenoid housing allows for versatility of experimental set-ups among diagnostic and target positions. Within the perpendicular field axis at the center there is 300 degrees of clearance which can be easily modified to meet the needs of a specific experiment, as well as an f/3 cone for transmitted or backscattered light. After initial design efforts, these solenoids are relatively inexpensive to manufacture.

Automatic vision system for analysis of microscopic behavior of flow and transport in porous media

NASA Astrophysics Data System (ADS)

Rashidi, Mehdi; Dehmeshki, Jamshid; Dickenson, Eric; Daemi, M. Farhang

1997-10-01

This paper describes the development of a novel automated and efficient vision system to obtain velocity and concentration measurement within a porous medium. An aqueous fluid lace with a fluorescent dye to microspheres flows through a transparent, refractive-index-matched column packed with transparent crystals. For illumination purposes, a planar sheet of laser passes through the column as a CCD camera records all the laser illuminated planes. Detailed microscopic velocity and concentration fields have been computed within a 3D volume of the column. For measuring velocities, while the aqueous fluid, laced with fluorescent microspheres, flows through the transparent medium, a CCD camera records the motions of the fluorescing particles by a video cassette recorder. The recorded images are acquired automatically frame by frame and transferred to the computer for processing, by using a frame grabber an written relevant algorithms through an RS-232 interface. Since the grabbed image is poor in this stage, some preprocessings are used to enhance particles within images. Finally, these enhanced particles are monitored to calculate velocity vectors in the plane of the beam. For concentration measurements, while the aqueous fluid, laced with a fluorescent organic dye, flows through the transparent medium, a CCD camera sweeps back and forth across the column and records concentration slices on the planes illuminated by the laser beam traveling simultaneously with the camera. Subsequently, these recorded images are transferred to the computer for processing in similar fashion to the velocity measurement. In order to have a fully automatic vision system, several detailed image processing techniques are developed to match exact images that have different intensities values but the same topological characteristics. This results in normalized interstitial chemical concentrations as a function of time within the porous column.

An improved schlieren method for measurement and automatic reconstruction of the far-field focal spot

PubMed Central

Wang, Zhengzhou; Hu, Bingliang; Yin, Qinye

2017-01-01

The schlieren method of measuring far-field focal spots offers many advantages at the Shenguang III laser facility such as low cost and automatic laser-path collimation. However, current methods of far-field focal spot measurement often suffer from low precision and efficiency when the final focal spot is merged manually, thereby reducing the accuracy of reconstruction. In this paper, we introduce an improved schlieren method to construct the high dynamic-range image of far-field focal spots and improve the reconstruction accuracy and efficiency. First, a detection method based on weak light beam sampling and magnification imaging was designed; images of the main and side lobes of the focused laser irradiance in the far field were obtained using two scientific CCD cameras. Second, using a self-correlation template matching algorithm, a circle the same size as the schlieren ball was dug from the main lobe cutting image and used to change the relative region of the main lobe cutting image within a 100×100 pixel region. The position that had the largest correlation coefficient between the side lobe cutting image and the main lobe cutting image when a circle was dug was identified as the best matching point. Finally, the least squares method was used to fit the center of the side lobe schlieren small ball, and the error was less than 1 pixel. The experimental results show that this method enables the accurate, high-dynamic-range measurement of a far-field focal spot and automatic image reconstruction. Because the best matching point is obtained through image processing rather than traditional reconstruction methods based on manual splicing, this method is less sensitive to the efficiency of focal-spot reconstruction and thus offers better experimental precision. PMID:28207758

Semi-automatic mapping of cultural heritage from airborne laser scanning using deep learning

NASA Astrophysics Data System (ADS)

Due Trier, Øivind; Salberg, Arnt-Børre; Holger Pilø, Lars; Tonning, Christer; Marius Johansen, Hans; Aarsten, Dagrun

2016-04-01

This paper proposes to use deep learning to improve semi-automatic mapping of cultural heritage from airborne laser scanning (ALS) data. Automatic detection methods, based on traditional pattern recognition, have been applied in a number of cultural heritage mapping projects in Norway for the past five years. Automatic detection of pits and heaps have been combined with visual interpretation of the ALS data for the mapping of deer hunting systems, iron production sites, grave mounds and charcoal kilns. However, the performance of the automatic detection methods varies substantially between ALS datasets. For the mapping of deer hunting systems on flat gravel and sand sediment deposits, the automatic detection results were almost perfect. However, some false detections appeared in the terrain outside of the sediment deposits. These could be explained by other pit-like landscape features, like parts of river courses, spaces between boulders, and modern terrain modifications. However, these were easy to spot during visual interpretation, and the number of missed individual pitfall traps was still low. For the mapping of grave mounds, the automatic method produced a large number of false detections, reducing the usefulness of the semi-automatic approach. The mound structure is a very common natural terrain feature, and the grave mounds are less distinct in shape than the pitfall traps. Still, applying automatic mound detection on an entire municipality did lead to a new discovery of an Iron Age grave field with more than 15 individual mounds. Automatic mound detection also proved to be useful for a detailed re-mapping of Norway's largest Iron Age grave yard, which contains almost 1000 individual graves. Combined pit and mound detection has been applied to the mapping of more than 1000 charcoal kilns that were used by an iron work 350-200 years ago. The majority of charcoal kilns were indirectly detected as either pits on the circumference, a central mound, or both. However, kilns with a flat interior and a shallow ditch along the circumference were often missed by the automatic detection method. The successfulness of automatic detection seems to depend on two factors: (1) the density of ALS ground hits on the cultural heritage structures being sought, and (2) to what extent these structures stand out from natural terrain structures. The first factor may, to some extent, be improved by using a higher number of ALS pulses per square meter. The second factor is difficult to change, and also highlights another challenge: how to make a general automatic method that is applicable in all types of terrain within a country. The mixed experience with traditional pattern recognition for semi-automatic mapping of cultural heritage led us to consider deep learning as an alternative approach. The main principle is that a general feature detector has been trained on a large image database. The feature detector is then tailored to a specific task by using a modest number of images of true and false examples of the features being sought. Results of using deep learning are compared with previous results using traditional pattern recognition.

Automatic Matching of Large Scale Images and Terrestrial LIDAR Based on App Synergy of Mobile Phone

NASA Astrophysics Data System (ADS)

Xia, G.; Hu, C.

2018-04-01

The digitalization of Cultural Heritage based on ground laser scanning technology has been widely applied. High-precision scanning and high-resolution photography of cultural relics are the main methods of data acquisition. The reconstruction with the complete point cloud and high-resolution image requires the matching of image and point cloud, the acquisition of the homonym feature points, the data registration, etc. However, the one-to-one correspondence between image and corresponding point cloud depends on inefficient manual search. The effective classify and management of a large number of image and the matching of large image and corresponding point cloud will be the focus of the research. In this paper, we propose automatic matching of large scale images and terrestrial LiDAR based on APP synergy of mobile phone. Firstly, we develop an APP based on Android, take pictures and record related information of classification. Secondly, all the images are automatically grouped with the recorded information. Thirdly, the matching algorithm is used to match the global and local image. According to the one-to-one correspondence between the global image and the point cloud reflection intensity image, the automatic matching of the image and its corresponding laser radar point cloud is realized. Finally, the mapping relationship between global image, local image and intensity image is established according to homonym feature point. So we can establish the data structure of the global image, the local image in the global image, the local image corresponding point cloud, and carry on the visualization management and query of image.

Wideband Holographic Digital Recording and Reproduction. Phase IV.

DTIC Science & Technology

1980-02-01

array of 128 acousto-optic ele- meats. The electrical energy is converted to acoustic waves within a glass crystal, so that when the light passes through...systems. An AO device is a block of transparent material (various types of glass , for example) through which we pass the laser beam that we want to...Clearance - .60 mm from cell Vignetting None None Glass Type Optional SF6 R ecord Mode Input Aperture 14 mm x 52mm 14mrm x 52rm Field Angle +12. 0

Material Processing with High Power CO2-Lasers

NASA Astrophysics Data System (ADS)

Bakowsky, Lothar

1986-10-01

After a period of research and development lasertechnique now is regarded as an important instrument for flexible, economic and fully automatic manufacturing. Especially cutting of flat metal sheets with high power C02-lasers and CNC controlled two or three axes handling systems is a wide spread. application. Three dimensional laser cutting, laser-welding and -heat treatment are just at the be ginning of industrial use in production lines. The main. advantages of laser technology. are - high. accuracy - high, processing velocity - law thermal distortion. - no tool abrasion. The market for laser material processing systems had 1985 a volume of 300 Mio S with growth rates between, 20 % and 30 %. The topic of this lecture are hiTrh. power CO2-lasers. Besides this systems two others are used as machining tools, Nd-YAG- and Eximer lasers. All applications of high. power CO2-lasers to industrial material processing show that high processing velocity and quality are only guaranteed in case of a stable intensity. profile on the workpiece. This is only achieved by laser systems without any power and mode fluctuations and by handling systems of high accuracy. Two applications in the automotive industry are described, below as examples for laser cutting and laser welding of special cylindrical motor parts.

Application of ESPI techniques for the study of dynamic vibrations

NASA Astrophysics Data System (ADS)

Krupka, Rene

2004-06-01

Full field optical measurement techniques have already entered into various fields of industrial applications covering static as well as dynamic phenomena. The electronic speckle pattern interferometry (ESPI) allows the non contact, sensitive and three dimensional measurement of displacements in the sub micron range of objects with dimensions from mm2 to m2. For dynamic and transient phenomena, the use of pulsed laser have already been reported for various applications and successfully proven for the determination of the structural response of different components. In this paper we would like to present recent developments in the field of pulsed ESPI applications where emphasis is put onto the full field measurement result. The use of a completely computer controlled system allows easy access to mode shape characterization, deformation measurements and the characterization of transient events like shock wave propagation. Recent developments of the 3D-PulseESPI technique led to a very compact and complete system with improved characteristics regarding robustness and operation. The integrated design of the illumination laser and sensors for image acquisition allows easy aiming and adjustments with respect to the object of inspection. The laser is completely computer controlled which is advantageously used in a completely automatic brake squeal inspection system, which captures the squealing signal, automatically fires the laser and provides the complete deformation map of the component under test. Examples of recent applications in the field of dynamic structure response, with an emphasis in the field of automotive applications are given.

Calculation of impulse laser rangefinders' utmost operating range with sensitivity in different weather

NASA Astrophysics Data System (ADS)

Chen, Yu-dan; Zhou, Bing; Ying, Jia-ju; Mao, Shao-juan; Qian, Xian-mei

2015-10-01

As one of the main weapons, impulse laser rangefinders have become the main object of the electro-optical countermeasures. So its real maximum range (defined as utmost operating range in the paper) becomes the most concerned index to evaluate the performance of electro-optical countermeasure weapons. A method for calculating laser rangefinders' utmost operating range by its sensitivity in different weather is obtained. Then a method by experiment for getting the sensitivity is supplied. By analyzing the experiment data which the detectivity is 40%-60%, the laser rangefinders' sensitivity is in the range of 1.7×10-5 W to 9.8×10-5 W. For the reason that in order to get an exact utmost operating range, the experiment accuracy of sensitivity is very important, in the last part of paper, the factors which influence the experiment accuracy of sensitivity are analyzed, such as circuit of automatic gain control, the fluctuation of laser power, incident angle of laser.

A Structured Light Sensor System for Tree Inventory

NASA Technical Reports Server (NTRS)

Chien, Chiun-Hong; Zemek, Michael C.

2000-01-01

Tree Inventory is referred to measurement and estimation of marketable wood volume in a piece of land or forest for purposes such as investment or for loan applications. Exist techniques rely on trained surveyor conducting measurements manually using simple optical or mechanical devices, and hence are time consuming subjective and error prone. The advance of computer vision techniques makes it possible to conduct automatic measurements that are more efficient, objective and reliable. This paper describes 3D measurements of tree diameters using a uniquely designed ensemble of two line laser emitters rigidly mounted on a video camera. The proposed laser camera system relies on a fixed distance between two parallel laser planes and projections of laser lines to calculate tree diameters. Performance of the laser camera system is further enhanced by fusion of information induced from structured lighting and that contained in video images. Comparison will be made between the laser camera sensor system and a stereo vision system previously developed for measurements of tree diameters.

A new approach to the form and position error measurement of the auto frame surface based on laser

NASA Astrophysics Data System (ADS)

Wang, Hua; Li, Wei

2013-03-01

Auto frame is a very large workpiece, with length up to 12 meters and width up to 2 meters, and it's very easy to know that it's inconvenient and not automatic to measure such a large workpiece by independent manual operation. In this paper we propose a new approach to reconstruct the 3D model of the large workpiece, especially the auto truck frame, based on multiple pulsed lasers, for the purpose of measuring the form and position errors. In a concerned area, it just needs one high-speed camera and two lasers. It is a fast, high-precision and economical approach.

Protection method for an optical information carrier

NASA Astrophysics Data System (ADS)

Pitsyuga, Vitaly V.; Kolesnikov, Michael Y.; Kosyak, Igor V.

1997-02-01

Now information protection on personal carriers (for example, cards) from an unauthorized access (UA) is a very important problem in connection with wide introduction of proper automatic systems for information processing in different spheres of human activity. These are financial, medical and information services, an access to restricted units and so on. There is proposed to use physical parameters of the special coating part (so-called restricted zone) to information protection on optical carriers (laser cards). There is formed restricted zone on the surface of the recording coating of a laser card. The unique information about every laser card to creating a protective passport from UA is obtained by readout of defects parameters.

Treatment of Previously Treated Facial Capillary Malformations: Results of Single-Center Retrospective Objective 3-Dimensional Analysis of the Efficacy of Large Spot 532 nm Lasers.

PubMed

Kwiek, Bartłomiej; Ambroziak, Marcin; Osipowicz, Katarzyna; Kowalewski, Cezary; Rożalski, Michał

2018-06-01

Current treatment of facial capillary malformations (CM) has limited efficacy. To assess the efficacy of large spot 532 nm lasers for the treatment of previously treated facial CM with the use of 3-dimensional (3D) image analysis. Forty-three white patients aged 6 to 59 were included in this study. Patients had 3D photography performed before and after treatment with a 532 nm Nd:YAG laser with large spot and contact cooling. Objective analysis of percentage improvement based on 3D digital assessment of combined color and area improvement (global clearance effect [GCE]) were performed. The median maximal improvement achieved during the treatment (GCE) was 59.1%. The mean number of laser procedures required to achieve this improvement was 6.2 (range 1-16). Improvement of minimum 25% (GCE25) was achieved by 88.4% of patients, a minimum of 50% (GCE50) by 61.1%, a minimum of 75% (GCE75) by 25.6%, and a minimum of 90% (GCE90) by 4.6%. Patients previously treated with pulsed dye lasers had a significantly less response than those treated with other modalities (GCE 37.3% vs 61.8%, respectively). A large spot 532 nm laser is effective in previously treated patients with facial CM.

Control Method for Video Guidance Sensor System

NASA Technical Reports Server (NTRS)

Howard, Richard T. (Inventor); Book, Michael L. (Inventor); Bryan, Thomas C. (Inventor)

2005-01-01

A method is provided for controlling operations in a video guidance sensor system wherein images of laser output signals transmitted by the system and returned from a target are captured and processed by the system to produce data used in tracking of the target. Six modes of operation are provided as follows: (i) a reset mode; (ii) a diagnostic mode; (iii) a standby mode; (iv) an acquisition mode; (v) a tracking mode; and (vi) a spot mode wherein captured images of returned laser signals are processed to produce data for all spots found in the image. The method provides for automatic transition to the standby mode from the reset mode after integrity checks are performed and from the diagnostic mode to the reset mode after diagnostic operations are commands is permitted only when the system is in the carried out. Further, acceptance of reset and diagnostic standby mode. The method also provides for automatic transition from the acquisition mode to the tracking mode when an acceptable target is found.

Automated diagnosis of fetal alcohol syndrome using 3D facial image analysis

PubMed Central

Fang, Shiaofen; McLaughlin, Jason; Fang, Jiandong; Huang, Jeffrey; Autti-Rämö, Ilona; Fagerlund, Åse; Jacobson, Sandra W.; Robinson, Luther K.; Hoyme, H. Eugene; Mattson, Sarah N.; Riley, Edward; Zhou, Feng; Ward, Richard; Moore, Elizabeth S.; Foroud, Tatiana

2012-01-01

Objectives Use three-dimensional (3D) facial laser scanned images from children with fetal alcohol syndrome (FAS) and controls to develop an automated diagnosis technique that can reliably and accurately identify individuals prenatally exposed to alcohol. Methods A detailed dysmorphology evaluation, history of prenatal alcohol exposure, and 3D facial laser scans were obtained from 149 individuals (86 FAS; 63 Control) recruited from two study sites (Cape Town, South Africa and Helsinki, Finland). Computer graphics, machine learning, and pattern recognition techniques were used to automatically identify a set of facial features that best discriminated individuals with FAS from controls in each sample. Results An automated feature detection and analysis technique was developed and applied to the two study populations. A unique set of facial regions and features were identified for each population that accurately discriminated FAS and control faces without any human intervention. Conclusion Our results demonstrate that computer algorithms can be used to automatically detect facial features that can discriminate FAS and control faces. PMID:18713153

Rapid measurement and compensation method of eccentricity in automatic profile measurement of the ICF capsule.

PubMed

Li, Shaobai; Wang, Yun; Wang, Qi; Ma, Xianxian; Wang, Longxiao; Zhao, Weiqian; Zhang, Xusheng

2018-05-10

In this paper, we propose a new measurement and compensation method for the eccentricity of the inertial confinement fusion (ICF) capsule, which combines computer vision and the laser differential confocal method to align the capsule in rotation measurement. This technique measures the eccentricity of the capsule by obtaining the sub-pixel profile with a moment-based algorithm, then performs the preliminary alignment by the two-dimensional adjustment. Next, we use the laser differential confocal sensor to measure the height data of the equatorial surface of the capsule by turning it around, then obtain and compensate the remaining eccentricity ultimately. This method is a non-contact, automatic, rapid, high-precision measurement and compensation technique of eccentricity for the capsule. Theoretical analyses and preliminary experiments indicate that the maximum measurement range of eccentricity of this proposed method is 1.8 mm for the capsule with a diameter of 1 mm, and it could eliminate the eccentricity to less than 0.5 μm in 30 s.

Control method for video guidance sensor system

NASA Technical Reports Server (NTRS)

Howard, Richard T. (Inventor); Book, Michael L. (Inventor); Bryan, Thomas C. (Inventor)

2005-01-01

A method is provided for controlling operations in a video guidance sensor system wherein images of laser output signals transmitted by the system and returned from a target are captured and processed by the system to produce data used in tracking of the target. Six modes of operation are provided as follows: (i) a reset mode; (ii) a diagnostic mode; (iii) a standby mode; (iv) an acquisition mode; (v) a tracking mode; and (vi) a spot mode wherein captured images of returned laser signals are processed to produce data for all spots found in the image. The method provides for automatic transition to the standby mode from the reset mode after integrity checks are performed and from the diagnostic mode to the reset mode after diagnostic operations are carried out. Further, acceptance of reset and diagnostic commands is permitted only when the system is in the standby mode. The method also provides for automatic transition from the acquisition mode to the tracking mode when an acceptable target is found.

High-precision radius automatic measurement using laser differential confocal technology

NASA Astrophysics Data System (ADS)

Jiang, Hongwei; Zhao, Weiqian; Yang, Jiamiao; Guo, Yongkui; Xiao, Yang

2015-02-01

A high precision radius automatic measurement method using laser differential confocal technology is proposed. Based on the property of an axial intensity curve that the null point precisely corresponds to the focus of the objective and the bipolar property, the method uses the composite PID (proportional-integral-derivative) control to ensure the steady movement of the motor for process of quick-trigger scanning, and uses least-squares linear fitting to obtain the position of the cat-eye and confocal positions, then calculates the radius of curvature of lens. By setting the number of measure times, precision auto-repeat measurement of the radius of curvature is achieved. The experiment indicates that the method has the measurement accuracy of better than 2 ppm, and the measuring repeatability is better than 0.05 μm. In comparison with the existing manual-single measurement, this method has a high measurement precision, a strong environment anti-interference capability, a better measuring repeatability which is only tenth of former's.

Development of automatic pre-tracking system for fillet weld based on laser trigonometry

NASA Astrophysics Data System (ADS)

Shen, Xiaoqin; Yu, Fusheng

2005-01-01

In this paper, an automatic fillet weld pre-tracking system for welding the work piece of lorry back boards with several bend in haul automobile is developed basing on laser trigonometry. The optical measuring head based on laser-PSD trigonometry is used as position sensor. It is placed in front of the traveling direction of welding wire to get the distances from welding wire to the two side boards of the welding lines, upper board and bottom board of the fillet weld respectively. A chip of AT89S52 is used as the micro controller in this system. The AC servomotors, ball-screws and straight guide rails constitute the sliding table to take welding wire move. The laser-PSD sensors pass through the vertical board, upper board and bottom board of the fillet weld when welding wire moves and then get the distance. The laser-PSD sensors output the analog signals. After A/D conversion, the digital signal is input into AT89S52 and calculated. Then the information of the position and lateral deviation of the welding wire when welding a certain position are gotten to control welding wires. So the weld pre-tracking for welding the work piece with long distance and large bend in haul automobile is realized. The position information is input into EEPROM to be saved for short time after handled by AT89S52. The information is as the welding position information as well as the speed adjusting data of the welding wire when it welds the several bend of the work piece. The practice indicates that this system has high pre-tracking precision, good anti-disturb ability, excellent reliability, easy operating ability and good adaptability to the field of production.

SU-E-T-99: Design and Development of Isocenter Parameter System for CT Simulation Laser Based On DICOM RT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luo, G

2014-06-01

Purpose: In order to receive DICOM files from treatment planning system and generate patient isocenter positioning parameter file for CT laser system automatically, this paper presents a method for communication with treatment planning system and calculation of isocenter parameter for each radiation field. Methods: Coordinate transformation and laser positioning file formats were analyzed, isocenter parameter was calculated via data from DICOM CT Data and DICOM RTPLAN file. An in-house software-DicomGenie was developed based on the object-oriented program platform-Qt with DCMTK SDK (Germany OFFIS company DICOM SDK) . DicomGenie was tested for accuracy using Philips CT simulation plan system (Tumor LOC,more » Philips) and A2J CT positioning laser system (Thorigny Sur Marne, France). Results: DicomGenie successfully established DICOM communication between treatment planning system, DICOM files were received by DicomGenie and patient laser isocenter information was generated accurately. Patient laser parameter data files can be used for for CT laser system directly. Conclusion: In-house software DicomGenie received and extracted DICOM data, isocenter laser positioning data files were created by DicomGenie and can be use for A2J laser positioning system.« less

Subsurface defects of fused silica optics and laser induced damage at 351 nm.

PubMed

Hongjie, Liu; Jin, Huang; Fengrui, Wang; Xinda, Zhou; Xin, Ye; Xiaoyan, Zhou; Laixi, Sun; Xiaodong, Jiang; Zhan, Sui; Wanguo, Zheng

2013-05-20

Many kinds of subsurface defects are always present together in the subsurface of fused silica optics. It is imperfect that only one kind of defects is isolated to investigate its impact on laser damage. Therefore it is necessary to investigate the impact of subsurface defects on laser induced damage of fused silica optics with a comprehensive vision. In this work, we choose the fused silica samples manufactured by different vendors to characterize subsurface defects and measure laser induced damage. Contamination defects, subsurface damage (SSD), optical-thermal absorption and hardness of fused silica surface are characterized with time-of-flight secondary ion mass spectrometry (TOF-SIMS), fluorescence microscopy, photo-thermal common-path interferometer and fully automatic micro-hardness tester respectively. Laser induced damage threshold and damage density are measured by 351 nm nanosecond pulse laser. The correlations existing between defects and laser induced damage are analyzed. The results show that Cerium element and SSD both have a good correlation with laser-induced damage thresholds and damage density. Research results evaluate process technology of fused silica optics in China at present. Furthermore, the results can provide technique support for improving laser induced damage performance of fused silica.

A spectroscopic approach to monitor the cut processing in pulsed laser osteotomy.

PubMed

Henn, Konrad; Gubaidullin, Gail G; Bongartz, Jens; Wahrburg, Jürgen; Roth, Hubert; Kunkel, Martin

2013-01-01

During laser osteotomy surgery, plasma arises at the place of ablation. It was the aim of this study to explore whether a spectroscopic analysis of this plasma would allow identification of the type of tissue that was affected by the laser. In an experimental setup (Rofin SCx10, CO(2) Slab Laser, wavelength 10.6 μm, pulse duration 80 μs, pulse repetition rate 200 Hz, max. output in cw-mode 100 W), the plasma spectra evoked by a pulsed laser, cutting 1-day postmortem pig and cow bones, were recorded. Spectra were compared to the reference spectrum of bone via correlation analysis. Our measurements show a clear differentiation between the plasma spectra when cutting either a bone or a soft tissue. The spectral changes could be detected from one to the next spectrum within 200 ms. Continuous surveillance of plasma spectra allows us to differentiate whether bone or soft tissue is hit by the last laser pulse. With this information, it may be possible to stop the laser when cutting undesired soft tissue and to design an automatic control of the ablation process.

Modular flexible ureteroscopy and holmium laser lithotripsy for the treatment of renal and proximal ureteral calculi: A single-surgeon experience of 382 cases.

PubMed

Yan, Zejun; Xie, Guohai; Yuan, Hesheng; Cheng, Yue

2015-10-01

To determine the safety and efficacy of modular flexible ureteroscopy and holmium laser lithotripsy for the treatment of renal and proximal ureteral calculi, a retrospective chart review of a single surgeon's 3-year modular flexible ureteroscopy experience was performed. All of the patients were treated with modular flexible ureteroscopy and holmium laser lithotripsy by a single surgeon. Stone-free status was defined as no fragments or a single fragment ≤4 mm in diameter at the 3-month follow-up. The procedure number, operative time, stone-free rates, repeat usage of the multilumen catheter, and perioperative complications were documented. The present study included 215 male patients and 167 female patients, with an average age of 48.5±13.7 years (range, 17-84 years). The mean stone size was 11.5±4.1 mm (range, 4-28 mm), and the mean total stone burden was 17.5±5.7 mm (range 15-46 mm). A total of 305 patients (79.8%) had a stone burden ≤20 mm, and 77 patients (20.2%) had a stone burden >20 mm. The mean number of primary procedures was 1.3±0.2 (range, 1-3). The stone-free rate following the first and the second procedure was 73.4 and 86.9%, respectively. The mean postoperative hospital stay was 3.1±1.2 days (range, 2-6 days). The highest clearance rates were observed for proximal ureteral stones (100%) and renal pelvic stones (88.7%), whereas the lowest clearance rates were observed for lower calyx stones (76.7%) and multiple calyx stones (77.8%). The higher the initial stone burden, the lower the postoperative stone-free rate (≤20 vs. >20 mm; 89.8 vs. 75.3%). The overall complication rate was 8.1%. The results of the present study suggest that modular flexible ureteroscopy with holmium laser lithotripsy may be considered the primary method for the treatment of renal and proximal ureteral calculi in select patients, due to its acceptable efficacy, low morbidity, and relatively low maintenance costs.

Pulsed dye laser treatment of rosacea using a novel 15 mm diameter treatment beam.

PubMed

Bernstein, Eric F; Schomacker, Kevin; Paranjape, Amit; Jones, Christopher J

2018-04-10

The pulsed-dye laser has been used to treat facial redness and rosacea for decades. Recent advances in dye laser technology enable 50% higher output energies supporting 50% larger treatment areas, and beam-diameters up to 15 mm with clinically-relevant fluences. In this study, we investigate this novel pulsed-dye laser using a 15 mm diameter beam for treatment of rosacea. Twenty subjects with erythemato-telangiectatic rosacea were enrolled in the study. A total of 4 monthly treatments were administered, first treating linear vessels with a 3 × 10 mm elliptical beam, then diffuse redness with a 15-mm diameter circular beam. Blinded assessment of digital, cross-polarized photographs taken 2 months following the last treatment was performed using an 11-point clearance scale. Nineteen subjects completed the study. Blinded reviewers correctly identified baseline photos in 55 out of the total of 57 images (96.5%). The blinded reviewers scored 17 of the 19 subjects with an improvement greater than 40%, and 11 of the 19 subjects greater than 50%. The average improvement was 53.9%. Side effects were limited to mild edema, mild to moderate erythema, and mild to moderate bruising. This study demonstrates that a newly designed pulsed-dye laser having a novel 15-mm diameter treatment beam improves the appearance of rosacea with a favorable safety profile. Lasers Surg. Med. 9999:1-5, 2018. © 2018 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc. © 2018 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.

Spray deposition inside multiple-row nursery trees with a laser-guided sprayer

USDA-ARS?s Scientific Manuscript database

Multiple-row container-grown trees require specially designed sprayers to achieve efficient spray delivery quality. A five-port air-assisted sprayer with both automatic and manual control modes was developed to discharge adequate spray deposition inside multiple-row tree plants. The sprayer resulted...

Recent Developments in the VISRAD 3-D Target Design and Radiation Simulation Code

NASA Astrophysics Data System (ADS)

Macfarlane, Joseph; Golovkin, Igor; Sebald, James

2017-10-01

The 3-D view factor code VISRAD is widely used in designing HEDP experiments at major laser and pulsed-power facilities, including NIF, OMEGA, OMEGA-EP, ORION, Z, and LMJ. It simulates target designs by generating a 3-D grid of surface elements, utilizing a variety of 3-D primitives and surface removal algorithms, and can be used to compute the radiation flux throughout the surface element grid by computing element-to-element view factors and solving power balance equations. Target set-up and beam pointing are facilitated by allowing users to specify positions and angular orientations using a variety of coordinates systems (e.g., that of any laser beam, target component, or diagnostic port). Analytic modeling for laser beam spatial profiles for OMEGA DPPs and NIF CPPs is used to compute laser intensity profiles throughout the grid of surface elements. VISRAD includes a variety of user-friendly graphics for setting up targets and displaying results, can readily display views from any point in space, and can be used to generate image sequences for animations. We will discuss recent improvements to conveniently assess beam capture on target and beam clearance of diagnostic components, as well as plans for future developments.

A comparative clinical and mycological study of Nd-YAG laser versus topical terbinafine in the treatment of onychomycosis.

PubMed

El-Tatawy, Rania A; Abd El-Naby, Naeim M; El-Hawary, Esraa E; Talaat, Raghda A Z

2015-10-01

Topical treatment of onychomycoses is time consuming, cost-intensive and subject to relatively high failure rates. Light-based devices may be effective treatment modalities. Aim of this work: To compare the clinical and mycological efficacy of Nd-YAG laser versus topical terbinafine in the treatment of onychomycosis. This study included 40 patients with onychomycosis randomized to receive four sessions of Nd-YAG laser (group A) or topical terbinafine twice daily for six months (group B). Follow-up was performed monthly. Mycological examination was done at third and sixth months following the start of treatment. After six months, all patients in group A showed marked improvement, while in group B only 50% of patients showed mild to moderate improvement. In addition, by the end of six months, 80% of the patients in group A showed mycological clearance, while all patients in group B still had positive cultures. Long pulse Nd-YAG laser therapy of onychomycosis is a safe and efficient method for treating onychomycosis. It is especially beneficial in elderly, compromised and hepatopathic patients for whom other alternative treatments could present some risks.

Two-dimensional surface strain measurement based on a variation of Yamaguchi's laser-speckle strain gauge

NASA Technical Reports Server (NTRS)

Barranger, John P.

1990-01-01

A novel optical method of measuring 2-D surface strain is proposed. Two linear strains along orthogonal axes and the shear strain between those axes is determined by a variation of Yamaguchi's laser-speckle strain gage technique. It offers the advantages of shorter data acquisition times, less stringent alignment requirements, and reduced decorrelation effects when compared to a previously implemented optical strain rosette technique. The method automatically cancels the translational and rotational components of rigid body motion while simplifying the optical system and improving the speed of response.

Remote laser spectroscopy of oil and gas deposits

NASA Astrophysics Data System (ADS)

Zhevlakov, A. P.; Bespalov, V. G.; Elizarov, V. V.; Grishkanich, A. S.; Kascheev, S. V.; Makarov, E. A.; Bogoslovsky, S. A.; Il'inskiy, A. A.

2014-06-01

We developed a Raman lidar with ultraspectral resolution for automatic airborne monitoring of pipeline leaks and for oil and gas exploration. Test flights indicate that a sensitivity of 6 ppm for methane and 2 ppm for hydrogen sulfide has been reached for leakage detection. The lidar is based on the CARS method with a Ti:Sapphire pump laser and a frequencydoubled YLF:Nd probe beam whose frequency is displaced by a BBO crystal. In ground-based experiments, a detection level of 3 to 10 molecules has been reached.

Laser-assisted chemical vapor deposition setup for fast synthesis of graphene patterns

NASA Astrophysics Data System (ADS)

Zhang, Chentao; Zhang, Jianhuan; Lin, Kun; Huang, Yuanqing

2017-05-01

An automatic setup based on the laser-assisted chemical vapor deposition method has been developed for the rapid synthesis of graphene patterns. The key components of this setup include a laser beam control and focusing unit, a laser spot monitoring unit, and a vacuum and flow control unit. A laser beam with precision control of laser power is focused on the surface of a nickel foil substrate by the laser beam control and focusing unit for localized heating. A rapid heating and cooling process at the localized region is induced by the relative movement between the focalized laser spot and the nickel foil substrate, which causes the decomposing of gaseous hydrocarbon and the out-diffusing of excess carbon atoms to form graphene patterns on the laser scanning path. All the fabrication parameters that affect the quality and number of graphene layers, such as laser power, laser spot size, laser scanning speed, pressure of vacuum chamber, and flow rates of gases, can be precisely controlled and monitored during the preparation of graphene patterns. A simulation of temperature distribution was carried out via the finite element method, providing a scientific guidance for the regulation of temperature distribution during experiments. A multi-layer graphene ribbon with few defects was synthesized to verify its performance of the rapid growth of high-quality graphene patterns. Furthermore, this setup has potential applications in other laser-based graphene synthesis and processing.

Guinea pig cochlear blood flow under definite sound exposure-hydrogen clearance measurement.

PubMed

Meyer, P; Kuhl, K D; Schmidt, R; Grützmacher, W

1991-01-01

Blood flow measurements were carried out on 18 coloured guinea pigs (8 animals served as control group) before and during definite sound exposure (12 kHz, 110 dB SPL). The exposure time amounted to 60 min. The anaesthesia was carried out according to the following schedule: a mixture consisting of 70 mg alpha-chloralose/kg b.w. and 400 mg urethane/kg b.w. was injected intraperitoneally. The relaxation was performed by means of i.p. application of 3 mg Tricuran/kg b.w./h. The hydrogen clearance measurements (HCM) were carried out under artificial respiration with control of arterial pH, endexpiratory CO2 content, as well as blood pressure and body temperature. After a duration of noise exposure of 30-45 min the cochlear blood flow reached an average level of 80% of the initial point. This level remained mainly unchanged until the end of noise exposure (60 min). Our HMC's confirm Laser Doppler flowmetry findings.

Performance Optimization of a Rotor Alone Nacelle for Acoustic Fan Testing

NASA Technical Reports Server (NTRS)

Cunningham, C. C.; Thompson, W. K.; Hughes, C. E.

2000-01-01

This paper describes the techniques, equipment, and results from the optimization of a two-axis traverse actuation system used to maintain concentricity between a sting-mounted fan and a wall-mounted nacelle in the 9 x 15 (9 Foot by 15 Foot Test Section) Low Speed Wind Tunnel (LSWT) at the NASA Glenn Research Center (GRC). The Rotor Alone Nacelle (RAN) system, developed at GRC by the Engineering Design and Analysis Division (EDAD) and the Acoustics Branch, used nacelle-mounted lasers and an automated control system to maintain concentricity as thermal and thrust operating loads displace the fan relative to the nacelle. This effort was critical to ensuring rig/facility safety and experimental consistency of the acoustic data from a statorless, externally supported nacelle configuration. Although the tip clearances were originally predicted to be about 0.020 in. at maximum rotor (fan) operating speed, proximity probe measurements showed that the nominal clearance was less than 0.004 in. As a result, the system was optimized through control-loop modifications, active laser cooling, data filtering and averaging, and the development of strict operational procedures. The resultant concentricity error of RAN was reduced to +/- 0.0031 in. in the Y-direction (horizontal) and +0.0035 in./-0.001 3 in. in the Z-direction (vertical), as determined by error analysis and experimental results. Based on the success of this project, the RAN system will be transitioned to other wind tunnel research programs at NASA GRC.

Insights on correlation dimension from dynamics mapping of three experimental nonlinear laser systems.

PubMed

McMahon, Christopher J; Toomey, Joshua P; Kane, Deb M

2017-01-01

We have analysed large data sets consisting of tens of thousands of time series from three Type B laser systems: a semiconductor laser in a photonic integrated chip, a semiconductor laser subject to optical feedback from a long free-space-external-cavity, and a solid-state laser subject to optical injection from a master laser. The lasers can deliver either constant, periodic, pulsed, or chaotic outputs when parameters such as the injection current and the level of external perturbation are varied. The systems represent examples of experimental nonlinear systems more generally and cover a broad range of complexity including systematically varying complexity in some regions. In this work we have introduced a new procedure for semi-automatically interrogating experimental laser system output power time series to calculate the correlation dimension (CD) using the commonly adopted Grassberger-Proccacia algorithm. The new CD procedure is called the 'minimum gradient detection algorithm'. A value of minimum gradient is returned for all time series in a data set. In some cases this can be identified as a CD, with uncertainty. Applying the new 'minimum gradient detection algorithm' CD procedure, we obtained robust measurements of the correlation dimension for many of the time series measured from each laser system. By mapping the results across an extended parameter space for operation of each laser system, we were able to confidently identify regions of low CD (CD < 3) and assign these robust values for the correlation dimension. However, in all three laser systems, we were not able to measure the correlation dimension at all parts of the parameter space. Nevertheless, by mapping the staged progress of the algorithm, we were able to broadly classify the dynamical output of the lasers at all parts of their respective parameter spaces. For two of the laser systems this included displaying regions of high-complexity chaos and dynamic noise. These high-complexity regions are differentiated from regions where the time series are dominated by technical noise. This is the first time such differentiation has been achieved using a CD analysis approach. More can be known of the CD for a system when it is interrogated in a mapping context, than from calculations using isolated time series. This has been shown for three laser systems and the approach is expected to be useful in other areas of nonlinear science where large data sets are available and need to be semi-automatically analysed to provide real dimensional information about the complex dynamics. The CD/minimum gradient algorithm measure provides additional information that complements other measures of complexity and relative complexity, such as the permutation entropy; and conventional physical measurements.

Insights on correlation dimension from dynamics mapping of three experimental nonlinear laser systems

PubMed Central

McMahon, Christopher J.; Toomey, Joshua P.

2017-01-01

Background We have analysed large data sets consisting of tens of thousands of time series from three Type B laser systems: a semiconductor laser in a photonic integrated chip, a semiconductor laser subject to optical feedback from a long free-space-external-cavity, and a solid-state laser subject to optical injection from a master laser. The lasers can deliver either constant, periodic, pulsed, or chaotic outputs when parameters such as the injection current and the level of external perturbation are varied. The systems represent examples of experimental nonlinear systems more generally and cover a broad range of complexity including systematically varying complexity in some regions. Methods In this work we have introduced a new procedure for semi-automatically interrogating experimental laser system output power time series to calculate the correlation dimension (CD) using the commonly adopted Grassberger-Proccacia algorithm. The new CD procedure is called the ‘minimum gradient detection algorithm’. A value of minimum gradient is returned for all time series in a data set. In some cases this can be identified as a CD, with uncertainty. Findings Applying the new ‘minimum gradient detection algorithm’ CD procedure, we obtained robust measurements of the correlation dimension for many of the time series measured from each laser system. By mapping the results across an extended parameter space for operation of each laser system, we were able to confidently identify regions of low CD (CD < 3) and assign these robust values for the correlation dimension. However, in all three laser systems, we were not able to measure the correlation dimension at all parts of the parameter space. Nevertheless, by mapping the staged progress of the algorithm, we were able to broadly classify the dynamical output of the lasers at all parts of their respective parameter spaces. For two of the laser systems this included displaying regions of high-complexity chaos and dynamic noise. These high-complexity regions are differentiated from regions where the time series are dominated by technical noise. This is the first time such differentiation has been achieved using a CD analysis approach. Conclusions More can be known of the CD for a system when it is interrogated in a mapping context, than from calculations using isolated time series. This has been shown for three laser systems and the approach is expected to be useful in other areas of nonlinear science where large data sets are available and need to be semi-automatically analysed to provide real dimensional information about the complex dynamics. The CD/minimum gradient algorithm measure provides additional information that complements other measures of complexity and relative complexity, such as the permutation entropy; and conventional physical measurements. PMID:28837602

Pairwise Trajectory Management (PTM): Concept Overview

NASA Technical Reports Server (NTRS)

Jones, Kenneth M.; Graff, Thomas J.; Chartrand, Ryan C.; Carreno, Victor; Kibler, Jennifer L.

2017-01-01

Pairwise Trajectory Management (PTM) is an Interval Management (IM) concept that utilizes airborne and ground-based capabilities to enable the implementation of airborne pairwise spacing capabilities in oceanic regions. The goal of PTM is to use airborne surveillance and tools to manage an "at or greater than" inter-aircraft spacing. Due to the precision of Automatic Dependent Surveillance-Broadcast (ADS-B) information and the use of airborne spacing guidance, the PTM minimum spacing distance will be less than distances a controller can support with current automation systems that support oceanic operations. Ground tools assist the controller in evaluating the traffic picture and determining appropriate PTM clearances to be issued. Avionics systems provide guidance information that allows the flight crew to conform to the PTM clearance issued by the controller. The combination of a reduced minimum distance and airborne spacing management will increase the capacity and efficiency of aircraft operations at a given altitude or volume of airspace. This paper provides an overview of the proposed application, description of a few key scenarios, high level discussion of expected air and ground equipment and procedure changes, overview of a potential flight crew human-machine interface that would support PTM operations and some initial PTM benefits results.

Mobile Laser Scanning Systems for Measuring the Clearance Gauge of Railways: State of Play, Testing and Outlook

PubMed Central

Mikrut, Sławomir; Kohut, Piotr; Pyka, Krystian; Tokarczyk, Regina; Barszcz, Tomasz; Uhl, Tadeusz

2016-01-01

The paper contains a survey of mobile scanning systems for measuring the railway clearance gauge. The research was completed as part of the project carried out for the PKP (PKP Polish Railway Lines S.A., Warsaw, Poland) in 2011–2013. The authors conducted experiments, including a search for the latest solutions relating to mobile measurement systems that meet the basic requirement. At the very least, these solutions needed to be accurate and have the ability for quick retrieval of data. In the paper, specifications and the characteristics of the component devices of the scanning systems are described. Based on experiments, the authors did some examination of the selected mobile systems to be applied for measuring the clearance gauge. The Riegl (VMX-250) and Z+F (Zoller + Fröhlich) Solution were tested. Additional test measurements were carried out within a 30-kilometer section of the Warsaw-Kraków route. These measurements were designed so as to provide various elements of the railway infrastructure, the track geometry and the installed geodetic control network. This ultimately made it possible to reduce the time for the preparation of geodetic reference measurements for the testing of the accuracy of the selected systems. Reference measurements included the use of the polar method to select profiles perpendicular to the axis of the track. In addition, the coordinates selected were well defined as measuring points of the objects of the infrastructure of the clearance gauge. All of the tested systems meet the accuracy requirements initially established (within the range of 2 cm as required by the PKP). The tested systems have shown their advantages and disadvantages. PMID:27187400

Dynamic in vivo imaging of small animal brain using pulsed laser diode-based photoacoustic tomography system.

PubMed

Upputuri, Paul Kumar; Pramanik, Manojit

2017-09-01

We demonstrate dynamic in vivo imaging using a low-cost portable pulsed laser diode (PLD)-based photoacoustic tomography system. The system takes advantage of an 803-nm PLD having high-repetition rate ∼7000  Hz combined with a fast-scanning single-element ultrasound transducer leading to a 5 s cross-sectional imaging. Cortical vasculature is imaged in scan time of 5 s with high signal-to-noise ratio ∼48. To examine the ability for dynamic imaging, we monitored the fast uptake and clearance process of indocyanine green in the rat brain. The system will find applications to study neurofunctional activities, characterization of pharmacokinetic, and biodistribution profiles in the development process of drugs or imaging agents. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Ultrasensitive dual-beam absorption and gain spectroscopy: applications for near-infrared and visible diode laser sensors

NASA Astrophysics Data System (ADS)

Allen, Mark G.; Carleton, Karen L.; Davis, Steven J.; Kessler, William J.; Otis, Charles E.; Palombo, Daniel A.; Sonnenfroh, David M.

1995-06-01

A dual-beam detection strategy with automatic balancing is described for ultrasensitive spectroscopy. Absorbances of 2 \\times 10-7 Hz-1/2 in free-space configurations and 5 \\times 10-6 Hz -1/2 in fiber-coupled configurations are demonstrated. With the dual-beam technique, atmospherically broadened absorption transitions may be resolved with InGaAsP, AlGaAs, and AlGaInP single-longitudinal-mode diode lasers. Applications to trace measurements of NO2 , O2, and H2O are described by the use of simple, inexpensive laser and detector systems. Small signal gain measurements on optically pumped I2 with a sensitivity of 10-5 are also reported.

The Use of Computer Vision Algorithms for Automatic Orientation of Terrestrial Laser Scanning Data

NASA Astrophysics Data System (ADS)

Markiewicz, Jakub Stefan

2016-06-01

The paper presents analysis of the orientation of terrestrial laser scanning (TLS) data. In the proposed data processing methodology, point clouds are considered as panoramic images enriched by the depth map. Computer vision (CV) algorithms are used for orientation, which are applied for testing the correctness of the detection of tie points and time of computations, and for assessing difficulties in their implementation. The BRISK, FASRT, MSER, SIFT, SURF, ASIFT and CenSurE algorithms are used to search for key-points. The source data are point clouds acquired using a Z+F 5006h terrestrial laser scanner on the ruins of Iłża Castle, Poland. Algorithms allowing combination of the photogrammetric and CV approaches are also presented.

Laser-based structural sensing and surface damage detection

NASA Astrophysics Data System (ADS)

Guldur, Burcu

Damage due to age or accumulated damage from hazards on existing structures poses a worldwide problem. In order to evaluate the current status of aging, deteriorating and damaged structures, it is vital to accurately assess the present conditions. It is possible to capture the in situ condition of structures by using laser scanners that create dense three-dimensional point clouds. This research investigates the use of high resolution three-dimensional terrestrial laser scanners with image capturing abilities as tools to capture geometric range data of complex scenes for structural engineering applications. Laser scanning technology is continuously improving, with commonly available scanners now capturing over 1,000,000 texture-mapped points per second with an accuracy of ~2 mm. However, automatically extracting meaningful information from point clouds remains a challenge, and the current state-of-the-art requires significant user interaction. The first objective of this research is to use widely accepted point cloud processing steps such as registration, feature extraction, segmentation, surface fitting and object detection to divide laser scanner data into meaningful object clusters and then apply several damage detection methods to these clusters. This required establishing a process for extracting important information from raw laser-scanned data sets such as the location, orientation and size of objects in a scanned region, and location of damaged regions on a structure. For this purpose, first a methodology for processing range data to identify objects in a scene is presented and then, once the objects from model library are correctly detected and fitted into the captured point cloud, these fitted objects are compared with the as-is point cloud of the investigated object to locate defects on the structure. The algorithms are demonstrated on synthetic scenes and validated on range data collected from test specimens and test-bed bridges. The second objective of this research is to combine useful information extracted from laser scanner data with color information, which provides information in the fourth dimension that enables detection of damage types such as cracks, corrosion, and related surface defects that are generally difficult to detect using only laser scanner data; moreover, the color information also helps to track volumetric changes on structures such as spalling. Although using images with varying resolution to detect cracks is an extensively researched topic, damage detection using laser scanners with and without color images is a new research area that holds many opportunities for enhancing the current practice of visual inspections. The aim is to combine the best features of laser scans and images to create an automatic and effective surface damage detection method, which will reduce the need for skilled labor during visual inspections and allow automatic documentation of related information. This work enables developing surface damage detection strategies that integrate existing condition rating criteria for a wide range damage types that are collected under three main categories: small deformations already existing on the structure (cracks); damage types that induce larger deformations, but where the initial topology of the structure has not changed appreciably (e.g., bent members); and large deformations where localized changes in the topology of the structure have occurred (e.g., rupture, discontinuities and spalling). The effectiveness of the developed damage detection algorithms are validated by comparing the detection results with the measurements taken from test specimens and test-bed bridges.

Kinect4FOG: monitoring and improving mobility in people with Parkinson's using a novel system incorporating the Microsoft Kinect v2.

PubMed

Amini, Amin; Banitsas, Konstantinos; Young, William R

2018-05-23

Parkinson's is a neurodegenerative condition associated with several motor symptoms including tremors and slowness of movement. Freezing of gait (FOG); the sensation of one's feet being "glued" to the floor, is one of the most debilitating symptoms associated with advanced Parkinson's. FOG not only contributes to falls and related injuries, but also compromises quality of life as people often avoid engaging in functional daily activities both inside and outside the home. In the current study, we describe a novel system designed to detect FOG and falling in people with Parkinson's (PwP) as well as monitoring and improving their mobility using laser-based visual cues cast by an automated laser system. The system utilizes a RGB-D sensor based on Microsoft Kinect v2 and a laser casting system consisting of two servo motors and an Arduino microcontroller. This system was evaluated by 15 PwP with FOG. Here, we present details of the system along with a summary of feedback provided by PwP. Despite limitations regarding its outdoor use, feedback was very positive in terms of domestic usability and convenience, where 12/15 PwP showed interest in installing and using the system at their homes. Implications for Rehabilitation Providing an automatic and remotely manageable monitoring system for PwP gait analysis and fall detection. Providing an automatic, unobtrusive and dynamic visual cue system for PwP based on laser line projection. Gathering feedback from PwP about the practical usage of the implemented system through focus group events.

a Low-Cost and Portable System for 3d Reconstruction of Texture-Less Objects

NASA Astrophysics Data System (ADS)

Hosseininaveh, A.; Yazdan, R.; Karami, A.; Moradi, M.; Ghorbani, F.

2015-12-01

The optical methods for 3D modelling of objects can be classified into two categories including image-based and range-based methods. Structure from Motion is one of the image-based methods implemented in commercial software. In this paper, a low-cost and portable system for 3D modelling of texture-less objects is proposed. This system includes a rotating table designed and developed by using a stepper motor and a very light rotation plate. The system also has eight laser light sources with very dense and strong beams which provide a relatively appropriate pattern on texture-less objects. In this system, regarding to the step of stepper motor, images are semi automatically taken by a camera. The images can be used in structure from motion procedures implemented in Agisoft software.To evaluate the performance of the system, two dark objects were used. The point clouds of these objects were obtained by spraying a light powders on the objects and exploiting a GOM laser scanner. Then these objects were placed on the proposed turntable. Several convergent images were taken from each object while the laser light sources were projecting the pattern on the objects. Afterward, the images were imported in VisualSFM as a fully automatic software package for generating an accurate and complete point cloud. Finally, the obtained point clouds were compared to the point clouds generated by the GOM laser scanner. The results showed the ability of the proposed system to produce a complete 3D model from texture-less objects.

Local measurement and numerical modeling of mass/heat transfer from a turbine blade in a linear cascade with tip clearance

NASA Astrophysics Data System (ADS)

Jin, Peitong

2000-11-01

Local mass/heat transfer measurements from the turbine blade near-tip and the tip surfaces are performed using the naphthalene sublimation technique. The experiments are conducted in a linear cascade consisting of five high-pressure blades with a central test-blade configuration. The incoming flow conditions are close to those of the gas turbine engine environment (boundary layer displacement thickness is about 0.01 of chord) with an exit Reynolds number of 6.2 x 105. The effects of tip clearance level (0.86%--6.90% of chord), mainstream Reynolds number and turbulence intensity (0.2 and 12.0%) are investigated. Two methods of flow visualization---oil and lampblack, laser light sheet smoke wire---as well as static pressure measurement on the blade surface are used to study the tip leakage flow and vortex in the cascade. In addition, numerical modeling of the flow and heat transfer processes in the linear cascade with different tip clearances is conducted using commercial software incorporating advanced turbulence models. The present study confirms many important results on the tip leakage flow and vortex from the literature, contributes to the current understanding in the effects of tip leakage flow and vortex on local heat transfer from the blade near-tip and the tip surfaces, and provides detailed local and average heat/mass transfer data applicable to turbine blade tip cooling design.

Effect of width and boundary conditions on meeting maneuvers on two-way separated cycle tracks.

PubMed

Garcia, Alfredo; Gomez, Fernando Agustin; Llorca, Carlos; Angel-Domenech, Antonio

2015-05-01

Cycle track design guidelines are rarely based on scientific studies. In the case of off-road two-way cycle tracks, a minimum width must facilitate both passing and meeting maneuvers, being meeting maneuvers the most frequent. This study developed a methodology to observe meeting maneuvers using an instrumented bicycle, equipped with video cameras, a GPS tracker, laser rangefinders and speed sensors. This bicycle collected data on six two-way cycle tracks ranging 1.3-2.15m width delimitated by different boundary conditions. The meeting maneuvers between the instrumented bicycle and every oncoming bicycle were characterized by the meeting clearance between the two bicycles, the speed of opposing bicycle and the reaction of the opposing rider: change in trajectory, stop pedaling or braking. The results showed that meeting clearance increased with the cycle track width and decreased if the cycle track had lateral obstacles, especially if they were higher than the bicycle handlebar. The speed of opposing bicycle shown the same tendency, although were more disperse. Opposing cyclists performed more reaction maneuvers on narrower cycle tracks and on cycle tracks with lateral obstacles to the handlebar height. Conclusions suggested avoiding cycle tracks narrower than 1.6m, as they present lower meeting clearances, lower bicycle speeds and frequent reaction maneuvers. Copyright © 2015 Elsevier Ltd. All rights reserved.

Automated Mounting Bias Calibration for Airborne LIDAR System

NASA Astrophysics Data System (ADS)

Zhang, J.; Jiang, W.; Jiang, S.

2012-07-01

Mounting bias is the major error source of Airborne LIDAR system. In this paper, an automated calibration method for estimating LIDAR system mounting parameters is introduced. LIDAR direct geo-referencing model is used to calculate systematic errors. Due to LIDAR footprints discretely sampled, the real corresponding laser points are hardly existence among different strips. The traditional corresponding point methodology does not seem to apply to LIDAR strip registration. We proposed a Virtual Corresponding Point Model to resolve the corresponding problem among discrete laser points. Each VCPM contains a corresponding point and three real laser footprints. Two rules are defined to calculate tie point coordinate from real laser footprints. The Scale Invariant Feature Transform (SIFT) is used to extract corresponding points in LIDAR strips, and the automatic flow of LIDAR system calibration based on VCPM is detailed described. The practical examples illustrate the feasibility and effectiveness of the proposed calibration method.

CO2 DIAL system: construction, measurements, and future development

NASA Astrophysics Data System (ADS)

Vicenik, Jiri

1999-07-01

A miniature CO2 DIAL system has been constructed. Dimension of the system are 500 X 450 X 240 mm, its mass is only 28 kg. The system consists of two tunable TEA CO2 lasers, receiving optics, IR detector, signal processing electronics and single chip microcomputer with display. The lasers are tuned manually by means of micrometric screw and are capable to generate pulses on more than 50 CO2 laser lines. The output energy is 50 mJ. The system was tested using various toxic gases and simulants, mostly at range 300 m, most of the measurements were done using pyrodetector in the receiver. The system shows good sensitivity, but it exhibits substantial instability of zero concentration. In the next stage the work will be concentrated on use of high-sensitivity MCT detector in the receiver and implementation of automatic tuning of lasers to the system.

Simplifications of the RELIEF flow tagging system for laboratory use. [Raman Excitation plus Laser Induced Electronic Fluorescence

NASA Technical Reports Server (NTRS)

Lempert, Walter R.; Zhang, Boying; Miles, Richard B.; Diskin, Glenn

1991-01-01

The use of an O2:He stimulated Raman cell to generate the Stokes beam for the Raman vibrational pumping step of the RELIEF (Raman Excitation plus Laser-Induced Electronic Fluorescence) flow tagging method is reported. Use of the Raman cell rather than a dye laser provides pump and Stokes beams which are automatically frequency matched and temporally and spatially overlapped. The Nd:YAG pump laser is operated multilongitudinal mode, which eliminates the need for injection seeding, resulting in decreased operation complexity and improved stability with respect to acoustic noise. Results are presented for 1st Stokes conversion efficiency and stimulated Brillouin backscattering loss and are compared to the case of pure O2. Scanning CARS measurements of the Q-branch lineshape for both pure O2 and the O2:He mixture are also presented.

Demonstration of multi-wavelength tunable fiber lasers based on a digital micromirror device processor.

PubMed

Ai, Qi; Chen, Xiao; Tian, Miao; Yan, Bin-bin; Zhang, Ying; Song, Fei-jun; Chen, Gen-xiang; Sang, Xin-zhu; Wang, Yi-quan; Xiao, Feng; Alameh, Kamal

2015-02-01

Based on a digital micromirror device (DMD) processor as the multi-wavelength narrow-band tunable filter, we demonstrate a multi-port tunable fiber laser through experiments. The key property of this laser is that any lasing wavelength channel from any arbitrary output port can be switched independently over the whole C-band, which is only driven by single DMD chip flexibly. All outputs display an excellent tuning capacity and high consistency in the whole C-band with a 0.02 nm linewidth, 0.055 nm wavelength tuning step, and side-mode suppression ratio greater than 60 dB. Due to the automatic power control and polarization design, the power uniformity of output lasers is less than 0.008 dB and the wavelength fluctuation is below 0.02 nm within 2 h at room temperature.

In situ industrial applications of optics; Proceedings of the Meeting, Brussels, Belgium, June 25-27, 1986

NASA Astrophysics Data System (ADS)

Ebbeni, Jean

Included in this volume are papers on real-time image enhancement by simple video systems, automatic identification and data collection via barcode laser scanning, the optimization of the cutting up of a strip of float glass, optical sensors for factory automation, and the use of a digital theodolite with infrared radiation. Attention is also given to ISIS (integrated shape imaging system), a new system for follow-up of scoliosis; optical diffraction extensometers; a cross-spectrum technique for high-sensitivity remote vibration analysis by optical interferometry; the compensation and measurement of any motion of three-dimensional objects in holographic interferometry; and stereoscreen. Additional papers are on holographic double pulse YAG lasers, miniature optic connectors, stress-field analysis in an adhesively bonded joint with laser photoelasticimetry, and the locking of the light pulse delay in externally triggered gas lasers.

New method for measuring the laser-induced damage threshold of optical thin film

NASA Astrophysics Data System (ADS)

Su, Jun-hong; Wang, Hong; Xi, Ying-xue

2012-10-01

The laser-induced damage threshold (LIDT) of thin film means that the thin film can withstand a maximum intensity of laser radiation. The film will be damaged when the irradiation under high laser intensity is greater than the value of LIDT. In this paper, an experimental platform with measurement operator interfaces and control procedures in the VB circumstance is built according to ISO11254-1. In order to obtain more accurate results than that with manual measurement, in the software system, a hardware device can be controlled by control widget on the operator interfaces. According to the sample characteristic, critical parameters of the LIDT measurement system such as spot diameter, damage threshold region, and critical damage pixel number are set up on the man-machine conversation interface, which could realize intelligent measurements of the LIDT. According to experimental data, the LIDT is obtained by fitting damage curve automatically.

Method using laser irradiation for the production of atomically clean crystalline silicon and germanium surfaces

DOEpatents

Ownby, Gary W.; White, Clark W.; Zehner, David M.

1981-01-01

This invention relates to a new method for removing surface impurities from crystalline silicon or germanium articles, such as off-the-shelf p- or n-type wafers to be doped for use as junction devices. The principal contaminants on such wafers are oxygen and carbon. The new method comprises laser-irradiating the contaminated surface in a non-reactive atmosphere, using one or more of Q-switched laser pulses whose parameters are selected to effect melting of the surface without substantial vaporization thereof. In a typical application, a plurality of pulses is used to convert a surface region of an off-the-shelf silicon wafer to an automatically clean region. This can be accomplished in a system at a pressure below 10.sup.-8 Torr, using Q-switched ruby-laser pulses having an energy density in the range of from about 60 to 190 MW/cm.sup.2.

Dual-beam laser autofocusing system based on liquid lens

NASA Astrophysics Data System (ADS)

Zhang, Fumin; Yao, Yannan; Qu, Xinghua; Zhang, Tong; Pei, Bing

2017-02-01

A dual-beam laser autofocusing system is designed in this paper. The autofocusing system is based on a liquid lens with less moving parts and fast response time, which makes the system simple, reliable, compact and fast. A novel scheme ;Time-sharing focus, fast conversion; is innovatively proposed. The scheme effectively solves the problem that the guiding laser and the working laser cannot focus at the same target point because of the existence of chromatic aberration. This scheme not only makes both guiding laser and working laser achieve optimal focusing in guiding stage and working stage respectively, but also greatly reduces the system complexity and simplifies the focusing process as well as makes autofocusing time of the working laser reduce to about 10 ms. In the distance range of 1 m to 30 m, the autofocusing spot size is kept under 4.3 mm at 30 m and just 0.18 mm at 1 m. The spot size is much less influenced by the target distance compared with the collimated laser with a micro divergence angle for its self-adaptivity. The dual-beam laser autofocusing system based on liquid lens is fully automatic, compact and efficient. It is fully meet the need of dynamicity and adaptivity and it will play an important role in a number of long-range control applications.

Beam uniformity of flat top lasers

NASA Astrophysics Data System (ADS)

Chang, Chao; Cramer, Larry; Danielson, Don; Norby, James

2015-03-01

Many beams that output from standard commercial lasers are multi-mode, with each mode having a different shape and width. They show an overall non-homogeneous energy distribution across the spot size. There may be satellite structures, halos and other deviations from beam uniformity. However, many scientific, industrial and medical applications require flat top spatial energy distribution, high uniformity in the plateau region, and complete absence of hot spots. Reliable standard methods for the evaluation of beam quality are of great importance. Standard methods are required for correct characterization of the laser for its intended application and for tight quality control in laser manufacturing. The International Organization for Standardization (ISO) has published standard procedures and definitions for this purpose. These procedures have not been widely adopted by commercial laser manufacturers. This is due to the fact that they are unreliable because an unrepresentative single-pixel value can seriously distort the result. We hereby propose a metric of beam uniformity, a way of beam profile visualization, procedures to automatically detect hot spots and beam structures, and application examples in our high energy laser production.

Multipixel frequency-domain imaging of spontaneous canine breast disease using fluorescent contrast agents

NASA Astrophysics Data System (ADS)

Reynolds, Jeffery S.; Thompson, Alan B.; Troy, Tamara L.; Mayer, Ralf H.; Waters, David J.; Sevick-Muraca, Eva M.

1999-07-01

In this paper we demonstrate the ability to detect the frequency-domain fluorescent signal from the contrast agent indocyanine green within the mammary chain of dogs with spontaneous mammary tumors. We use a gain-modulated image intensifier to rapidly capture multi-pixel images of the fluorescent modulation amplitude, modulation phase, and average intensity signals. Excitation is provided by a 100 MHz amplitude-modulated, 780 nm laser diode. Time series images of the uptake and clearance of the contrast agent in the diseased tissue are also presented.

Interior Reconstruction Using the 3d Hough Transform

NASA Astrophysics Data System (ADS)

Dumitru, R.-C.; Borrmann, D.; Nüchter, A.

2013-02-01

Laser scanners are often used to create accurate 3D models of buildings for civil engineering purposes, but the process of manually vectorizing a 3D point cloud is time consuming and error-prone (Adan and Huber, 2011). Therefore, the need to characterize and quantify complex environments in an automatic fashion arises, posing challenges for data analysis. This paper presents a system for 3D modeling by detecting planes in 3D point clouds, based on which the scene is reconstructed at a high architectural level through removing automatically clutter and foreground data. The implemented software detects openings, such as windows and doors and completes the 3D model by inpainting.

Efficacy and safety of Ho:YAG laser lithotripsy for ureteroscopic removal of proximal and distal ureteral calculi.

PubMed

Khoder, Wael Y; Bader, Markus; Sroka, Ronald; Stief, Christian; Waidelich, Raphaela

2014-08-08

Laser lithotripsy is an established endourological modality. Ho:YAG laser have broadened the indications for ureteroscopic stone managements to include larger stone sizes throughout the whole upper urinary tract. Aim of current work is to assess efficacy and safety of Ho:YAG laser lithotripsy during retrograde ureteroscopic management of ureteral calculi in different locations. 88 patients were treated with ureteroscopic Ho:YAG laser lithotripsy in our institute. Study endpoint was the number of treatments until the patient was stone-free. Patients were classified according to the location of their stones as Group I (distal ureteric stones, 51 patients) and group II (proximal ureteral stones, 37). Group I patients have larger stones as Group II (10.70 mm vs. 8.24 mm, respectively, P = 0.020). Overall stone free rate for both groups was 95.8%. The mean number of procedures for proximal calculi was 1.1 ± 0.1 (1-3) and for distal calculi was 1.0 ± 0.0. The initial treatment was more successful in patients with distal ureteral calculi (100% vs. 82.40%, respectively, P = 0.008). No significant difference in the stone free rate was noticed after the second laser procedure for stones smaller versus larger than 10 mm (100% versus 94.1%, P = 0.13). Overall complication rate was 7.9% (Clavien II und IIIb). Overall and grade-adjusted complication rates were not dependent on the stone location. No laser induced complications were noticed. The use of the Ho:YAG laser appears to be an adequate tool to disintegrate ureteral calculi independent of primary location. Combination of the semirigid and flexible ureteroscopes as well as the appropriate endourologic tools could likely improve the stone clearance rates for proximal calculi regardless of stone-size.

Carbon Dioxide Laser Ablation of Basal Cell Carcinoma with Visual Guidance by Reflectance Confocal Microscopy: A Proof of Principle Pilot Study

PubMed Central

Hibler, B.P.; Sierra, H.; Cordova, M.; Phillips, W.; Rajadhyaksha, M.; Nehal, K.S.; Rossi, A.M.

2016-01-01

Background Laser ablation is an alternative, non-surgical treatment modality for low-risk basal cell carcinoma (BCC); however, lack of confirmative tumour destruction or residual tumour presence has been a limiting factor to adoption. Reflectance confocal microscopy (RCM) provides non-invasive, cellular-level resolution imaging of the skin and is capable of identifying tumour. Objective To evaluate the use of RCM to guide carbon dioxide (CO2) laser ablation of BCC, confirm destruction, and correlate findings with histology. Methods RCM was used pre-ablation to evaluate for features of BCC. Ablation was performed with a CO2 laser, and the response rapidly assessed using handheld RCM to evaluate for residual tumour. Confirmative pathology was used to verify confocal imaging. Results RCM imaging identified tumour pre-ablation with features not identified on normal, surrounding skin. Post-ablation, RCM documented complete removal of tumour in six cases and residual tumour in two. Histologic examination identified the ablated area and confirmed clearance of tumour in the six aforementioned cases and corroborated confocal findings for residual tumour in the other two cases. Conclusions We report successful treatment of superficial and nodular BCC using CO2 laser ablation augmented by RCM imaging for pre-ablation guidance and verification of tumour removal post-ablation. Akin to complete circumferential and deep margin control techniques, using RCM helps to map peripheral and deep BCC margins to hone in on areas exhibiting persistent tumour after ablation. CO2 laser ablation visually guided by RCM can help circumvent previously cited limiting factors of laser ablation for tumour destruction by providing cellular-level resolution imaging of tumour and margin assessment in between each laser pass and post-ablation. PMID:26800657

Carbon dioxide laser ablation of basal cell carcinoma with visual guidance by reflectance confocal microscopy: a proof-of-principle pilot study.

PubMed

Hibler, B P; Sierra, H; Cordova, M; Phillips, W; Rajadhyaksha, M; Nehal, K S; Rossi, A M

2016-06-01

Laser ablation is an alternative, nonsurgical treatment modality for low-risk basal cell carcinoma (BCC). However, lack of confirmative tumour destruction or residual tumour presence has been a limiting factor to its adoption. Reflectance confocal microscopy (RCM) provides noninvasive, cellular-level resolution imaging of the skin and is capable of identifying tumour. To evaluate the use of RCM to guide carbon dioxide (CO2 ) laser ablation of BCC, confirm destruction and correlate findings with histology. RCM was used preablation to evaluate for features of BCC. Ablation was performed with a CO2 laser, and the response rapidly assessed using handheld RCM to evaluate for residual tumour. Confirmative pathology was used to verify confocal imaging. Preablation RCM imaging identified tumour with features not identified on normal, surrounding skin. Postablation, RCM documented complete removal of tumour in six cases and residual tumour in two. Histological examination identified the ablated area and confirmed clearance of tumour in the six aforementioned cases and corroborated confocal findings for residual tumour in the other two cases. We report successful treatment of superficial and nodular BCC using CO2 laser ablation augmented by RCM imaging for preablation guidance and verification of tumour removal postablation. Akin to complete circumferential and deep margin control techniques, using RCM helps to map peripheral and deep BCC margins to hone in on areas exhibiting persistent tumour after ablation. CO2 laser ablation visually guided by RCM can help circumvent previously cited limiting factors of laser ablation for tumour destruction by providing cellular-level resolution imaging of tumour and margin assessment in between each laser pass and postablation. © 2016 British Association of Dermatologists.

Automatic Extraction of Road Markings from Mobile Laser Scanning Data

NASA Astrophysics Data System (ADS)

Ma, H.; Pei, Z.; Wei, Z.; Zhong, R.

2017-09-01

Road markings as critical feature in high-defination maps, which are Advanced Driver Assistance System (ADAS) and self-driving technology required, have important functions in providing guidance and information to moving cars. Mobile laser scanning (MLS) system is an effective way to obtain the 3D information of the road surface, including road markings, at highway speeds and at less than traditional survey costs. This paper presents a novel method to automatically extract road markings from MLS point clouds. Ground points are first filtered from raw input point clouds using neighborhood elevation consistency method. The basic assumption of the method is that the road surface is smooth. Points with small elevation-difference between neighborhood are considered to be ground points. Then ground points are partitioned into a set of profiles according to trajectory data. The intensity histogram of points in each profile is generated to find intensity jumps in certain threshold which inversely to laser distance. The separated points are used as seed points to region grow based on intensity so as to obtain road mark of integrity. We use the point cloud template-matching method to refine the road marking candidates via removing the noise clusters with low correlation coefficient. During experiment with a MLS point set of about 2 kilometres in a city center, our method provides a promising solution to the road markings extraction from MLS data.

Automatic registration of Iphone images to LASER point clouds of the urban structures using shape features

NASA Astrophysics Data System (ADS)

Sirmacek, B.; Lindenbergh, R. C.; Menenti, M.

2013-10-01

Fusion of 3D airborne laser (LIDAR) data and terrestrial optical imagery can be applied in 3D urban modeling and model up-dating. The most challenging aspect of the fusion procedure is registering the terrestrial optical images on the LIDAR point clouds. In this article, we propose an approach for registering these two different data from different sensor sources. As we use iPhone camera images which are taken in front of the interested urban structure by the application user and the high resolution LIDAR point clouds of the acquired by an airborne laser sensor. After finding the photo capturing position and orientation from the iPhone photograph metafile, we automatically select the area of interest in the point cloud and transform it into a range image which has only grayscale intensity levels according to the distance from the image acquisition position. We benefit from local features for registering the iPhone image to the generated range image. In this article, we have applied the registration process based on local feature extraction and graph matching. Finally, the registration result is used for facade texture mapping on the 3D building surface mesh which is generated from the LIDAR point cloud. Our experimental results indicate possible usage of the proposed algorithm framework for 3D urban map updating and enhancing purposes.

Visual servoing of a laser ablation based cochleostomy

NASA Astrophysics Data System (ADS)

Kahrs, Lüder A.; Raczkowsky, Jörg; Werner, Martin; Knapp, Felix B.; Mehrwald, Markus; Hering, Peter; Schipper, Jörg; Klenzner, Thomas; Wörn, Heinz

2008-03-01

The aim of this study is a defined, visually based and camera controlled bone removal by a navigated CO II laser on the promontory of the inner ear. A precise and minimally traumatic opening procedure of the cochlea for the implantation of a cochlear implant electrode (so-called cochleostomy) is intended. Harming the membrane linings of the inner ear can result in damage of remaining organ functions (e.g. complete deafness or vertigo). A precise tissue removal by a laser-based bone ablation system is investigated. Inside the borehole the pulsed laser beam is guided automatically over the bone by using a two mirror galvanometric scanner. The ablation process is controlled by visual servoing. For the detection of the boundary layers of the inner ear the ablation area is monitored by a color camera. The acquired pictures are analyzed by image processing. The results of this analysis are used to control the process of laser ablation. This publication describes the complete system including image processing algorithms and the concept for the resulting distribution of single laser pulses. The system has been tested on human cochleae in ex-vivo studies. Further developments could lead to safe intraoperative openings of the cochlea by a robot based surgical laser instrument.

Mechanisms and time course of menthol-induced cutaneous vasodilation

PubMed Central

Craighead, Daniel H.; McCartney, Nathaniel B.; Tumlinson, James H.; Alexander, Lacy M.

2017-01-01

Menthol is a vasoactive compound that is widely used in topical analgesic agents. Menthol induces cutaneous vasodilation, however the underlying mechanisms are unknown. Determining the rates of appearance and clearance of menthol in the skin is important for optimizing topical treatment formulation and dosing. The purpose of this study was to determine the mechanisms contributing to menthol-mediated cutaneous vasodilation and to establish a time course for menthol appearance/clearance in the skin. Ten young (23±1 years, 5 males 5 females) subjects participated in two protocols. In study 1, four intradermal microdialysis fibers were perfused with increasing doses of menthol (0.1-500mM) and inhibitors for nitric oxide (NO), endothelium derived hyperpolarizing factors (EDHFs), and sensory nerves. Skin blood flow was measured with laser Doppler flowmetry and normalized to %CVCmax. In study 2, two intradermal microdialysis fibers were perfused with lactated Ringer's solution. 0.017mL•cm-2 of a 4% menthol gel was placed over each fiber. 5μL samples of dialysate from the microdialysis fibers were collected every 30 minutes and analyzed for the presence of menthol with high performance gas chromatography/mass spectrometry. Skin blood flow (laser speckle contrast imaging) and subjective ratings of menthol sensation were simultaneously obtained with dialysate samples. In study 1, menthol induced cutaneous vasodilation at all doses ≥100mM (all p<0.05). However, inhibition of either NO, EDHFs, or sensory nerves fully inhibited menthol-mediated vasodilation (all p>0.05). In study 2, significant menthol was detected in dialysate 30 minutes post menthol application (0.89ng, p=0.0002). Relative to baseline, cutaneous vasodilation was elevated from minutes 15-45 and ratings of menthol sensation were elevated from minute 5-60 post menthol application (all p<0.05). Menthol induces cutaneous vasodilation in the skin through multiple vasodilator pathways, including NO, EDHF, and sensory nerves. Topical menthol is detectable in the skin within 30 minutes and is cleared by 60 minutes. Skin blood flow and perceptual measures follow a similar time course as menthol appearance/clearance. PMID:27899298

Tuneable powerful UV laser system with UV noise eater

NASA Astrophysics Data System (ADS)

Kobtsev, Sergey; Radnatarov, Daba; Khripunov, Sergey; Zarudnev, Yurii

2018-02-01

The present work for the first time presents the study of a laser system delivering into the fibre up to 250 mW of CW radiation tuneable across the 275-310-nm range with the output line width less than 5 GHz and stability of UV output power within 1%. This system can automatically set the output radiation wavelength within the range of 275-310 nm to the precision of 2 pm. UV output power stabilisation is provided by a newly proposed by the authors noise eating technology. This paper discusses details of the developed technology and the results of its application.

Laser triangulation method for measuring the size of parking claw

NASA Astrophysics Data System (ADS)

Liu, Bo; Zhang, Ming; Pang, Ying

2017-10-01

With the development of science and technology and the maturity of measurement technology, the 3D profile measurement technology has been developed rapidly. Three dimensional measurement technology is widely used in mold manufacturing, industrial inspection, automatic processing and manufacturing, etc. There are many kinds of situations in scientific research and industrial production. It is necessary to transform the original mechanical parts into the 3D data model on the computer quickly and accurately. At present, many methods have been developed to measure the contour size, laser triangulation is one of the most widely used methods.

CMOS Active-Pixel Image Sensor With Intensity-Driven Readout

NASA Technical Reports Server (NTRS)

Langenbacher, Harry T.; Fossum, Eric R.; Kemeny, Sabrina

1996-01-01

Proposed complementary metal oxide/semiconductor (CMOS) integrated-circuit image sensor automatically provides readouts from pixels in order of decreasing illumination intensity. Sensor operated in integration mode. Particularly useful in number of image-sensing tasks, including diffractive laser range-finding, three-dimensional imaging, event-driven readout of sparse sensor arrays, and star tracking.

From Laser Scanning to Finite Element Analysis of Complex Buildings by Using a Semi-Automatic Procedure.

PubMed

Castellazzi, Giovanni; D'Altri, Antonio Maria; Bitelli, Gabriele; Selvaggi, Ilenia; Lambertini, Alessandro

2015-07-28

In this paper, a new semi-automatic procedure to transform three-dimensional point clouds of complex objects to three-dimensional finite element models is presented and validated. The procedure conceives of the point cloud as a stacking of point sections. The complexity of the clouds is arbitrary, since the procedure is designed for terrestrial laser scanner surveys applied to buildings with irregular geometry, such as historical buildings. The procedure aims at solving the problems connected to the generation of finite element models of these complex structures by constructing a fine discretized geometry with a reduced amount of time and ready to be used with structural analysis. If the starting clouds represent the inner and outer surfaces of the structure, the resulting finite element model will accurately capture the whole three-dimensional structure, producing a complex solid made by voxel elements. A comparison analysis with a CAD-based model is carried out on a historical building damaged by a seismic event. The results indicate that the proposed procedure is effective and obtains comparable models in a shorter time, with an increased level of automation.

Nonlinear automatic landing control of unmanned aerial vehicles on moving platforms via a 3D laser radar

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hervas, Jaime Rubio; Tang, Hui; Reyhanoglu, Mahmut

2014-12-10

This paper presents a motion tracking and control system for automatically landing Unmanned Aerial Vehicles (UAVs) on an oscillating platform using Laser Radar (LADAR) observations. The system itself is assumed to be mounted on a ship deck. A full nonlinear mathematical model is first introduced for the UAV. The ship motion is characterized by a Fourier transform based method which includes a realistic characterization of the sea waves. LADAR observation models are introduced and an algorithm to process those observations for yielding the relative state between the vessel and the UAV is presented, from which the UAV's state relative tomore » an inertial frame can be obtained and used for feedback purposes. A sliding mode control algorithm is derived for tracking a landing trajectory defined by a set of desired waypoints. An extended Kalman filter (EKF) is proposed to account for process and observation noises in the design of a state estimator. The effectiveness of the control algorithm is illustrated through a simulation example.« less

Automatic alternative phase-shift mask CAD layout tool for gate shrinkage of embedded DRAM in logic below 0.18 μm

NASA Astrophysics Data System (ADS)

Ohnuma, Hidetoshi; Kawahira, Hiroichi

1998-09-01

An automatic alternative phase shift mask (PSM) pattern layout tool has been newly developed. This tool is dedicated for embedded DRAM in logic device to shrink gate line width with improving line width controllability in lithography process with a design rule below 0.18 micrometers by the KrF excimer laser exposure. The tool can crete Levenson type PSM used being coupled with a binary mask adopting a double exposure method for positive photo resist. By using graphs, this tool automatically creates alternative PSM patterns. Moreover, it does not give any phase conflicts. By adopting it to actual embedded DRAM in logic cells, we have provided 0.16 micrometers gate resist patterns at both random logic and DRAM areas. The patterns were fabricated using two masks with the double exposure method. Gate line width has been well controlled under a practical exposure-focus window.

Diagnostic support for glaucoma using retinal images: a hybrid image analysis and data mining approach.

PubMed

Yu, Jin; Abidi, Syed Sibte Raza; Artes, Paul; McIntyre, Andy; Heywood, Malcolm

2005-01-01

The availability of modern imaging techniques such as Confocal Scanning Laser Tomography (CSLT) for capturing high-quality optic nerve images offer the potential for developing automatic and objective methods for diagnosing glaucoma. We present a hybrid approach that features the analysis of CSLT images using moment methods to derive abstract image defining features. The features are then used to train classifers for automatically distinguishing CSLT images of normal and glaucoma patient. As a first, in this paper, we present investigations in feature subset selction methods for reducing the relatively large input space produced by the moment methods. We use neural networks and support vector machines to determine a sub-set of moments that offer high classification accuracy. We demonstratee the efficacy of our methods to discriminate between healthy and glaucomatous optic disks based on shape information automatically derived from optic disk topography and reflectance images.

Reflector automatic acquisition and pointing based on auto-collimation theodolite.

PubMed

Luo, Jun; Wang, Zhiqian; Wen, Zhuoman; Li, Mingzhu; Liu, Shaojin; Shen, Chengwu

2018-01-01

An auto-collimation theodolite (ACT) for reflector automatic acquisition and pointing is designed based on the principle of autocollimators and theodolites. First, the principle of auto-collimation and theodolites is reviewed, and then the coaxial ACT structure is developed. Subsequently, the acquisition and pointing strategies for reflector measurements are presented, which first quickly acquires the target over a wide range and then points the laser spot to the charge coupled device zero position. Finally, experiments are conducted to verify the acquisition and pointing performance, including the calibration of the ACT, the comparison of the acquisition mode and pointing mode, and the accuracy measurement in horizontal and vertical directions. In both directions, a measurement accuracy of ±3″ is achieved. The presented ACT is suitable for automatic pointing and monitoring the reflector over a small scanning area and can be used in a wide range of applications such as bridge structure monitoring and cooperative target aiming.

Evaluation of Model Recognition for Grammar-Based Automatic 3d Building Model Reconstruction

NASA Astrophysics Data System (ADS)

Yu, Qian; Helmholz, Petra; Belton, David

2016-06-01

In recent years, 3D city models are in high demand by many public and private organisations, and the steadily growing capacity in both quality and quantity are increasing demand. The quality evaluation of these 3D models is a relevant issue both from the scientific and practical points of view. In this paper, we present a method for the quality evaluation of 3D building models which are reconstructed automatically from terrestrial laser scanning (TLS) data based on an attributed building grammar. The entire evaluation process has been performed in all the three dimensions in terms of completeness and correctness of the reconstruction. Six quality measures are introduced to apply on four datasets of reconstructed building models in order to describe the quality of the automatic reconstruction, and also are assessed on their validity from the evaluation point of view.

Precision digital control systems

NASA Astrophysics Data System (ADS)

Vyskub, V. G.; Rozov, B. S.; Savelev, V. I.

This book is concerned with the characteristics of digital control systems of great accuracy. A classification of such systems is considered along with aspects of stabilization, programmable control applications, digital tracking systems and servomechanisms, and precision systems for the control of a scanning laser beam. Other topics explored are related to systems of proportional control, linear devices and methods for increasing precision, approaches for further decreasing the response time in the case of high-speed operation, possibilities for the implementation of a logical control law, and methods for the study of precision digital control systems. A description is presented of precision automatic control systems which make use of electronic computers, taking into account the existing possibilities for an employment of computers in automatic control systems, approaches and studies required for including a computer in such control systems, and an analysis of the structure of automatic control systems with computers. Attention is also given to functional blocks in the considered systems.

Reflector automatic acquisition and pointing based on auto-collimation theodolite

NASA Astrophysics Data System (ADS)

Luo, Jun; Wang, Zhiqian; Wen, Zhuoman; Li, Mingzhu; Liu, Shaojin; Shen, Chengwu

2018-01-01

An auto-collimation theodolite (ACT) for reflector automatic acquisition and pointing is designed based on the principle of autocollimators and theodolites. First, the principle of auto-collimation and theodolites is reviewed, and then the coaxial ACT structure is developed. Subsequently, the acquisition and pointing strategies for reflector measurements are presented, which first quickly acquires the target over a wide range and then points the laser spot to the charge coupled device zero position. Finally, experiments are conducted to verify the acquisition and pointing performance, including the calibration of the ACT, the comparison of the acquisition mode and pointing mode, and the accuracy measurement in horizontal and vertical directions. In both directions, a measurement accuracy of ±3″ is achieved. The presented ACT is suitable for automatic pointing and monitoring the reflector over a small scanning area and can be used in a wide range of applications such as bridge structure monitoring and cooperative target aiming.

Design and Implementation of Multifunctional Automatic Drilling End Effector

NASA Astrophysics Data System (ADS)

Wang, Zhanxi; Qin, Xiansheng; Bai, Jing; Tan, Xiaoqun; Li, Jing

2017-03-01

In order to realize the automatic drilling in aircraft assembly, a drilling end effector is designed by integrating the pressure unit, drilling unit, measurement unit, control system and frame structure. In order to reduce the hole deviation, this paper proposes a vertical normal adjustment program based on 4 laser distance sensors. The actual normal direction of workpiece surface can be calculated through the sensors measurements, and then robot posture is adjusted to realize the hole deviation correction. A base detection method is proposed to detect and locate the hole automatically by using the camera and the reference hole. The experiment results show that the position accuracy of the system is less than 0.3mm, and the normal precision is less than 0.5°. The drilling end effector and robot can greatly improve the efficiency of the aircraft parts and assembly quality, and reduce the product development cycle.

Novel use of non-ablative fractional photothermolysis for café-au-lait macules in darker skin types.

PubMed

Balaraman, Brundha; Ravanfar-Jordan, Parisa; Friedman, Paul M

2017-01-01

The removal of café-au-lait macules (CALMs) in patients with darker skin phototypes poses a significant challenge due to limited available therapeutic options and increased risk of adverse effects, including permanent scarring and further dyspigmentation. Herein, we demonstrate the novel use of non-ablative fractional photothermolysis for the safe removal of CALMs in individuals with Fitzpatrick skin type (FST) IV-V. Retrospective analysis of four patients (FST IV-V) with CALMs revealed that three of these patients had greater than 50% clearance after multiple treatment sessions with the non-ablative fractional 1,550-nm erbium-doped fiber laser. This report demonstrates the utility and safety of non-ablative fractional resurfacing in the treatment of CALMs in darker skin phototypes. Lasers Surg. Med. 49:84-87, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Development and creation of a remote-controlled underwater laser induced breakdown spectrometer for analysis of the chemical composition of sea water and bottom sediments

NASA Astrophysics Data System (ADS)

Golik, Sergey S.; Mayor, Alexsander Yu.; Proschenko, Dmitriy Yu.; Ilyin, Alexey A.; Nagorniy, Ivan G.; Biryukova, Yuliya S.; Babiy, Michael Yu.; Golik, Natalia N.; Gevorgyan, Tigran A.; Lisitsa, Vladimir V.; Borovskiy, Anton V.; Kulchin, Yuri N.

2017-10-01

The developed underwater laser induced breakdown spectrometer consists of two units: 1- remotely operated vehicle (ROV) with the next main characteristics: work deep - up to 150 meters, maximum speed of immersion 1 m/s, maximum cruise velocity - 2 m/s and 2 - spectrometer unit (SU) consist of a DPSS Nd: YAG laser excitation source (double pulse with 50 mJ energy for each pulse at wavelength 1064 nm, pulse width 12 ns and pulse repetition rate 1-15 Hz, DF251, SOL Instruments), a spectrum recording system (Maya HR4000 or 2000 Pro spectrometer, Ocean Optics) and microcomputer. These two units are connected by Ethernet network and registered spectral data are automatically processed in a MATLAB platform.

Digital dental surface registration with laser scanner for orthodontics set-up planning

NASA Astrophysics Data System (ADS)

Alcaniz-Raya, Mariano L.; Albalat, Salvador E.; Grau Colomer, Vincente; Monserrat, Carlos A.

1997-05-01

We present an optical measuring system based on laser structured light suitable for its diary use in orthodontics clinics that fit four main requirements: (1) to avoid use of stone models, (2) to automatically discriminate geometric points belonging to teeth and gum, (3) to automatically calculate diagnostic parameters used by orthodontists, (4) to make use of low cost and easy to use technology for future commercial use. Proposed technique is based in the use of hydrocolloids mould used by orthodontists for stone model obtention. These mould of the inside of patient's mouth are composed of very fluent materials like alginate or hydrocolloids that reveal fine details of dental anatomy. Alginate mould are both very easy to obtain and very low costly. Once captured, alginate moulds are digitized by mean of a newly developed and patented 3D dental scanner. Developed scanner is based in the optical triangulation method based in the projection of a laser line on the alginate mould surface. Line deformation gives uncalibrated shape information. Relative linear movements of the mould with respect to the sensor head gives more sections thus obtaining a full 3D uncalibrated dentition model. Developed device makes use of redundant CCD in the sensor head and servocontrolled linear axis for mould movement. Last step is calibration to get a real and precise X, Y, Z image. All the process is done automatically. The scanner has been specially adapted for 3D dental anatomy capturing in order to fulfill specific requirements such as: scanning time, accuracy, security and correct acquisition of 'hidden points' in alginate mould. Measurement realized on phantoms with known geometry quite similar to dental anatomy present errors less than 0,1 mm. Scanning of global dental anatomy is 2 minutes, and generation of 3D graphics of dental cast takes approximately 30 seconds in a Pentium-based PC.

IR lasers in a struggle against dangerous cosmic objects

NASA Astrophysics Data System (ADS)

Kuzyakov, Boris A.

2001-03-01

Humanity can struggle with the small dangerous cosmic objects in our time and its parameter knowledge are needed. A present paper deals with prospects for the perspective of the laser methods applications for a dangerous asteroids discovering and a remote sensing and for the course correction systems of the influence expedients. The cosmic IR lasers will be used for remote sensing measurement of the various cosmic objects parameters: dimensions are more than 50 m, velocity is more than 10 km/s. The laser methods have the good perspectives among a large fleet of diagnostics technical means. The more effective CO2-laser parameters were defined for the solar systems smaller bodies velocity analysis. The laser is supplied with modulated laser radiation and an automatic tuning optical system. The CO2-lidars are needed for the asteroids detections and remote sensing at the distances of 30,000 km to 1 Mkm. A laser Doppler anemometer method with adaptive selection is used. The power calculations were made for the various asteroids in a cosmic space. The possibilities are estimated for remote sensing and for the course correction systems of the influence expedients also. The such system must be good for the distances nearby 12600 km, as the asteroids velocity can be more than 70 km/s.

Effective treatment of etanercept and phototherapy-resistant psoriasis using the excimer laser.

PubMed

Park, Kelly K; Swan, James; Koo, John

2012-03-15

Treatment of moderate-to-severe plaque psoriasis often requires the use of phototherapy or systemic therapy, which includes immunosuppressants, retinoids, and biologic agents. Although biologic use is becoming increasingly popular, it is not uncommon for patients to experience treatment failure. We describe a patient who had a suboptimal response to etanercept monotherapy after twelve weeks of induction dosing (50 mg twice weekly), as well as to a combination of etanercept (50 mg once weekly-maintenance dosing) and narrowband ultraviolet B (NB-UVB) phototherapy three times weekly for an additional twelve weeks. Noticeable improvement was noted after the addition of NB-UVB and the patient's promising response to phototherapy influenced further management. Etanercept and NB-UVB were discontinued and the patient was initiated on excimer laser treatments twice weekly. After 4 weeks, the patient had a 75 percent reduction in Psoriasis Area Severity Index (PASI) score and after 7 weeks had over 95 percent clearance of psoriasis. The unique properties of the excimer laser may account for its clinical efficacy in our patient as well as in other cases of recalcitrant psoriasis. We propose that the excimer laser be considered in cases of biologic or conventional phototherapy failure in addition to being a standard treatment option or adjunct for the treatment of psoriasis.

Complete resolution of minocycline pigmentation following a single treatment with non-ablative 1550-nm fractional resurfacing in combination with the 755-nm Q-switched alexandrite laser.

PubMed

Vangipuram, Ramya K; DeLozier, Whitney L; Geddes, Elizabeth; Friedman, Paul M

2016-03-01

Pigmentation secondary to minocycline ingestion is an uncommon adverse event affecting 3.7-14.8% of treated individuals for which few effective therapies are available. Three patterns of minocycline pigmentation have a characteristic clinical and histological appearance. The pigment composition in each variety is different and occurs at varying skin depths. Accordingly, a tailored approach according to the type of minocycline pigmentation is crucial for treatment success. The purpose of this intervention was to evaluate the efficacy of non-ablative fractional photothermolysis in combination with the Q-switched alexandrite laser for the treatment of type I minocycline pigmentation on the face. A patient with type I minocycline pigmentation was treated with non-ablative 1550-nm fractional photothermolysis followed immediately by 755-nm Q-switched alexandrite laser and then observed clinically to determine the outcome of this modality. The patient was seen in clinic 1 month later following her single treatment session and 100% clearance of all blue facial pigment was observed. Non-ablative fractional photothermolysis in combination with the 755-nm Q-switched alexandrite laser should be considered for treatment of type I minocycline pigmentation. © 2015 Wiley Periodicals, Inc.

Laser Anemometer Measurements of the Flow Field in a 4:1 Pressure Ratio Centrifugal Impeller

NASA Technical Reports Server (NTRS)

Skoch, G. J.; Prahst, P. S.; Wernet, M. P.; Wood, J. R.; Strazisar, A. J.

1997-01-01

A laser-doppler anemometer was used to obtain flow-field velocity measurements in a 4:1 pressure ratio, 4.54 kg/s (10 lbm/s), centrifugal impeller, with splitter blades and backsweep, which was configured with a vaneless diffuser. Measured through-flow velocities are reported for ten quasi-orthogonal survey planes at locations ranging from 1% to 99% of main blade chord. Measured through-flow velocities are compared to those predicted by a 3-D viscous steady flow analysis (Dawes) code. The measurements show the development and progression through the impeller and vaneless diffuser of a through-flow velocity deficit which results from the tip clearance flow and accumulation of low momentum fluid centrifuged from the blade and hub surfaces. Flow traces from the CFD analysis show the origin of this deficit which begins to grow in the inlet region of the impeller where it is first detected near the suction surface side of the passage. It then moves toward the pressure side of the channel, due to the movement of tip clearance flow across the impeller passage, where it is cut by the splitter blade leading edge. As blade loading increases toward the rear of the channel the deficit region is driven back toward the suction surface by the cross-passage pressure gradient. There is no evidence of a large wake region that might result from flow separation and the impeller efficiency is relatively high. The flow field in this impeller is quite similar to that documented previously by NASA Lewis in a large low-speed backswept impeller.

Miniature solid-state lasers for pointing, illumination, and warning devices

NASA Astrophysics Data System (ADS)

Brown, D. C.; Singley, J. M.; Yager, E.; Kowalewski, K.; Lotito, B.; Guelzow, J.; Hildreth, J.; Kuper, J. W.

2008-04-01

In this paper we review the current status of and progress towards higher power and more wavelength diverse diode-pumped solid-state miniature lasers. Snake Creek Lasers now offers unprecedented continuous wave (CW) output power from 9.0 mm and 5.6 mm TO type packages, including the smallest green laser in the world, the MicroGreen TM laser, and the highest density green laser in the world, the MiniGreen TM laser. In addition we offer an infrared laser, the MiniIR TM, operating at 1064 nm, and have just introduced a blue Mini laser operating at 473 nm in a 9.0 mm package. Recently we demonstrated over 1 W of output power at 1064 nm from a 12 mm TO type package, and green output power from 300-500 mW from the same 12 mm package. In addition, the company is developing a number of other innovative new miniature CW solid-state lasers operating at 750 nm, 820 nm, 458 nm, and an eye-safe Q-switched laser operating at 1550 nm. We also review recently demonstrated combining volume Bragg grating (VBG) technology has been combined with automatic power control (APC) to produce high power MiniGreen TM lasers whose output is constant to +/- 10 % over a wide temperature range, without the use of a thermoelectric cooler (TEC). This technology is expected to find widespread application in military and commercial applications where wide temperature operation is particularly important. It has immediate applications in laser pointers, illuminators, and laser flashlights, and displays.

Expression of key ion channels in the rat cardiac conduction system by laser capture microdissection and quantitative real-time PCR.

PubMed

Ou, Yan; Niu, Xiao-lin; Ren, Fu-xian

2010-09-01

The objective of this study was to investigate the molecular basis of the inferior nodal extension (INE) in the atrioventricular junctional area that accounts for arrhythmias. The INE was separated from the adult rat heart by laser capture microdissection. The mRNA expression of ion channels was detected by quantitative real-time PCR. Hierarchical clustering was used to demonstrate clustering of expression of genes in sections. The mRNA expression of HCN4, Ca(v)3.1 and Ca(v)3.2 was high in the INE, atrioventricular node and sino-atrial node, and that of Ca(v)3.2 high in Purkinje fibres. Although the expression of HCN1 and Ca(v)1.3 was low in the rat heart, it was relatively higher in the INE, atrioventricular node and sino-atrial node than in right atrial and right ventricular (working) myocytes. Both HCN2 and Ca(v)1.2 were expressed at higher levels in working myocytes than in nodal tissues and in the INE. Hierarchical clustering analysis demonstrated that the expression of the HCN and calcium channels in INE was similar to that in the slow-response automatic cells and different from that in working myocytes and Purkinje fibres. The expression of HCN and calcium channels in the INE of the adult rat heart is similar to that of slow-response automatic cells and provides a substrate for automatic phase 4 depolarization in cells.

Automatic detection of measurement points for non-contact vibrometer-based diagnosis of cardiac arrhythmias

NASA Astrophysics Data System (ADS)

Metzler, Jürgen; Kroschel, Kristian; Willersinn, Dieter

2017-03-01

Monitoring of the heart rhythm is the cornerstone of the diagnosis of cardiac arrhythmias. It is done by means of electrocardiography which relies on electrodes attached to the skin of the patient. We present a new system approach based on the so-called vibrocardiogram that allows an automatic non-contact registration of the heart rhythm. Because of the contactless principle, the technique offers potential application advantages in medical fields like emergency medicine (burn patient) or premature baby care where adhesive electrodes are not easily applicable. A laser-based, mobile, contactless vibrometer for on-site diagnostics that works with the principle of laser Doppler vibrometry allows the acquisition of vital functions in form of a vibrocardiogram. Preliminary clinical studies at the Klinikum Karlsruhe have shown that the region around the carotid artery and the chest region are appropriate therefore. However, the challenge is to find a suitable measurement point in these parts of the body that differs from person to person due to e. g. physiological properties of the skin. Therefore, we propose a new Microsoft Kinect-based approach. When a suitable measurement area on the appropriate parts of the body are detected by processing the Kinect data, the vibrometer is automatically aligned on an initial location within this area. Then, vibrocardiograms on different locations within this area are successively acquired until a sufficient measuring quality is achieved. This optimal location is found by exploiting the autocorrelation function.

Controlled study of excimer and pulsed dye lasers in the treatment of psoriasis.

PubMed

Taibjee, S M; Cheung, S-T; Laube, S; Lanigan, S W

2005-11-01

The excimer laser delivers high energy monochromatic ultraviolet (UV) B at 308 nm. Advantages over conventional UV sources include targeting of lesional skin, reducing cumulative dose and inducing faster clearance. Studies of the pulsed dye laser (PDL) in psoriasis report between 57% and 82% response rates; remission may extend to 15 months. To our knowledge, this is the first study assessing both excimer and PDL in psoriasis. We conducted a within-patient controlled prospective trial of treatment of localized plaque psoriasis. Twenty-two adult patients, mean Psoriasis Area and Severity Index 7.1, were recruited. Fifteen patients completed the full treatment, of which 13 were followed up to 1 year. Two selected plaques were treated with excimer twice weekly and V Beam PDL, pretreated with salicylic acid (SA), every 4 weeks, respectively. Two additional plaques, treated with SA alone or untreated, served as controls. The primary outcome measures were: (i) changes in plaque-modified Psoriasis Activity and Severity Index (PSI) scores from baseline to end of treatment; (ii) clinical response to treatment (CR(T)), assessed by serial photographs; (iii) percentage of plaques clear at the end of treatment; and (iv) percentage of plaques clear at 1-year follow-up. The secondary outcome measures were: (i) number of laser treatments to clearance; (ii) time to relapse; (iii) frequency of side-effects; and (iv) qualitative observations with SIAscope. The mean improvement in PSI was 4.7 (SD 2.1) with excimer and 2.7 (SD 2.4) with PDL. PSI improvement was significantly greater in excimer than PDL (P = 0.003) or both control plaques (P < 0.001). CR(T) indicated 13 patients responded best with excimer, two patients best with PDL, and in seven patients there was no difference between the two lasers. CR(T) was significantly greater for excimer than PDL (P = 0.003) or both controls (P < 0.001). CR(T) was also significantly greater for PDL than SA alone (P = 0.004) or untreated control (P =0.002). Nine (41%) patients cleared with excimer, after mean 8.7, median 10 weeks treatment. Seven of these nine patients were followed up to 1 year; four remained clear, two relapsed at 1 month, and one at 6 months. Six (27%) patients cleared with PDL, after mean 3.3, median four treatments. All six patients were followed up to 1 year; four remained clear, one relapsed at 4 months and one at 9 months. Despite common side-effects including blistering and hyperpigmentation, patient satisfaction was high. Serial images obtained with the SIAscope during treatment indicated different mechanisms of action of the two lasers. Excimer and V Beam PDL are useful treatments for plaque psoriasis. Although the excimer appears to be on average more efficacious, a subset of patients may respond better to PDL. Long-term remission is achievable with both lasers.

Helios: a Multi-Purpose LIDAR Simulation Framework for Research, Planning and Training of Laser Scanning Operations with Airborne, Ground-Based Mobile and Stationary Platforms

NASA Astrophysics Data System (ADS)

Bechtold, S.; Höfle, B.

2016-06-01

In many technical domains of modern society, there is a growing demand for fast, precise and automatic acquisition of digital 3D models of a wide variety of physical objects and environments. Laser scanning is a popular and widely used technology to cover this demand, but it is also expensive and complex to use to its full potential. However, there might exist scenarios where the operation of a real laser scanner could be replaced by a computer simulation, in order to save time and costs. This includes scenarios like teaching and training of laser scanning, development of new scanner hardware and scanning methods, or generation of artificial scan data sets to support the development of point cloud processing and analysis algorithms. To test the feasibility of this idea, we have developed a highly flexible laser scanning simulation framework named Heidelberg LiDAR Operations Simulator (HELIOS). HELIOS is implemented as a Java library and split up into a core component and multiple extension modules. Extensible Markup Language (XML) is used to define scanner, platform and scene models and to configure the behaviour of modules. Modules were developed and implemented for (1) loading of simulation assets and configuration (i.e. 3D scene models, scanner definitions, survey descriptions etc.), (2) playback of XML survey descriptions, (3) TLS survey planning (i.e. automatic computation of recommended scanning positions) and (4) interactive real-time 3D visualization of simulated surveys. As a proof of concept, we show the results of two experiments: First, a survey planning test in a scene that was specifically created to evaluate the quality of the survey planning algorithm. Second, a simulated TLS scan of a crop field in a precision farming scenario. The results show that HELIOS fulfills its design goals.

SigVox - A 3D feature matching algorithm for automatic street object recognition in mobile laser scanning point clouds

NASA Astrophysics Data System (ADS)

Wang, Jinhu; Lindenbergh, Roderik; Menenti, Massimo

2017-06-01

Urban road environments contain a variety of objects including different types of lamp poles and traffic signs. Its monitoring is traditionally conducted by visual inspection, which is time consuming and expensive. Mobile laser scanning (MLS) systems sample the road environment efficiently by acquiring large and accurate point clouds. This work proposes a methodology for urban road object recognition from MLS point clouds. The proposed method uses, for the first time, shape descriptors of complete objects to match repetitive objects in large point clouds. To do so, a novel 3D multi-scale shape descriptor is introduced, that is embedded in a workflow that efficiently and automatically identifies different types of lamp poles and traffic signs. The workflow starts by tiling the raw point clouds along the scanning trajectory and by identifying non-ground points. After voxelization of the non-ground points, connected voxels are clustered to form candidate objects. For automatic recognition of lamp poles and street signs, a 3D significant eigenvector based shape descriptor using voxels (SigVox) is introduced. The 3D SigVox descriptor is constructed by first subdividing the points with an octree into several levels. Next, significant eigenvectors of the points in each voxel are determined by principal component analysis (PCA) and mapped onto the appropriate triangle of a sphere approximating icosahedron. This step is repeated for different scales. By determining the similarity of 3D SigVox descriptors between candidate point clusters and training objects, street furniture is automatically identified. The feasibility and quality of the proposed method is verified on two point clouds obtained in opposite direction of a stretch of road of 4 km. 6 types of lamp pole and 4 types of road sign were selected as objects of interest. Ground truth validation showed that the overall accuracy of the ∼170 automatically recognized objects is approximately 95%. The results demonstrate that the proposed method is able to recognize street furniture in a practical scenario. Remaining difficult cases are touching objects, like a lamp pole close to a tree.

A modular approach to detection and identification of defects in rough lumber

Treesearch

Sang Mook Lee; A. Lynn Abbott; Daniel L. Schmoldt

2001-01-01

This paper describes a prototype scanning system that can automatically identify several important defects on rough hardwood lumber. The scanning system utilizes 3 laser sources and an embedded-processor camera to capture and analyze profile and gray-scale images. The modular approach combines the detection of wane (the curved sides of a board, possibly containing...

Aesthetic ultrasound therapy

NASA Astrophysics Data System (ADS)

Barthe, Peter G.; Slayton, Michael H.

2012-10-01

Ultrasound provides key benefits in aesthetic surgery compared to laser and RF based energy sources. We present results of research, development, pre-clinical and clinical studies, regulatory clearance and commercialization of a revolutionary non-invasive aesthetic ultrasound imaging and therapy system. Clinical applications for this platform include non-invasive face-lifts, brow-lifts, and neck-lifts achieved through fractionated treatment of the superficial musculoaponeurotic system (SMAS) and subcutaneous tissue. Treatment consists of placing a grid of micro-coagulative lesions on the order of 1 mm3 at depths in skin of 1 to 6 mm, source energy levels of 0.1 to 3 J, and spacing on the order of 1.5 mm, from 4 to 10 MHz dual-mode image/treat transducers. System details are described, as well as a regulatory pathway consisting of acoustic and bioheat simulations, source characterization (hydrophone, radiation force, and Schlieren), pre-clinical studies (porcine skin ex vivo, in vivo, and human cadaver), human safety studies (treat and resect) and efficacy trials which culminated in FDA clearance (2009) under a new device classification and world-wide usage. Clinical before and after photographs are presented which validate the clinical approach.

Novel treatment of Hori's nevus: A combination of fractional nonablative 2,940-nm Er:YAG and low-fluence 1,064-nm Q-switched Nd:YAG laser.

PubMed

Tian, Brian Wei Cheng Anthony

2015-01-01

To demonstrate a combination laser therapy to treat Hori's nevus. A prospective study. A Singapore-based clinic. Five female patients, aged 30-46 years, with bilateral malar Hori's nevus. Photographs were taken before treatment and 1 month after laser treatment was completed. These were graded by three independent physicians. The patients were also asked to grade their treatment response subjectively. They were followed up for a total of 3 months after laser treatment to monitor recurrence. The fractional nonablative 2,940-nm Er:YAG laser with a fluence of 0.7 J/cm(2), spot size 12 mm, and frequency 15 Hz was used to perform a full-face single-pass treatment. Subsequently, a second pass and third pass over Hori's nevi were done bilaterally till the clinical endpoint of skin whitening. The 1,064-nm Q-switched (QS) Nd:YAG at a fluence of 2.0 J/cm(2), frequency 2 Hz, and 4-mm spot size was used to deliver multiple passes over Hori's nevus till erythema with mild petechiae appeared. We repeated the treatment once a week for 3 more consecutive weeks. All five patients had above 80% improvement in their pigmentation and two (skin type III) achieved complete 100% clearance. Based on the patients' subjective assessments, all five of them expressed satisfaction and felt that their pigmentation had improved. There were no complications noted. The fractional nonablative 2940 nm Er:YAG laser and Q-switched 1064nm laser Nd:YAG combination is an effective and safe treatment for Hori's nevus.

Novel treatment of Hori's nevus: A combination of fractional nonablative 2,940-nm Er:YAG and low-fluence 1,064-nm Q-switched Nd:YAG laser

PubMed Central

Tian, Brian Wei Cheng Anthony

2015-01-01

Objective: To demonstrate a combination laser therapy to treat Hori's nevus. Design: A prospective study. Setting: A Singapore-based clinic. Participants: Five female patients, aged 30-46 years, with bilateral malar Hori's nevus. Measurements: Photographs were taken before treatment and 1 month after laser treatment was completed. These were graded by three independent physicians. The patients were also asked to grade their treatment response subjectively. They were followed up for a total of 3 months after laser treatment to monitor recurrence. Materials and Methods: The fractional nonablative 2,940-nm Er:YAG laser with a fluence of 0.7 J/cm2, spot size 12 mm, and frequency 15 Hz was used to perform a full-face single-pass treatment. Subsequently, a second pass and third pass over Hori's nevi were done bilaterally till the clinical endpoint of skin whitening. The 1,064-nm Q-switched (QS) Nd:YAG at a fluence of 2.0 J/cm2, frequency 2 Hz, and 4-mm spot size was used to deliver multiple passes over Hori's nevus till erythema with mild petechiae appeared. We repeated the treatment once a week for 3 more consecutive weeks. Results: All five patients had above 80% improvement in their pigmentation and two (skin type III) achieved complete 100% clearance. Based on the patients’ subjective assessments, all five of them expressed satisfaction and felt that their pigmentation had improved. There were no complications noted. Conclusion: The fractional nonablative 2940 nm Er:YAG laser and Q-switched 1064nm laser Nd:YAG combination is an effective and safe treatment for Hori's nevus. PMID:26865788

Treatment of Laugier-Hunziker syndrome with the Q-switched alexandrite laser in 22 Chinese patients.

PubMed

Zuo, Ya-Gang; Ma, Dong-Lai; Jin, Hong-Zhong; Liu, Yue-Hua; Wang, Hong-Wei; Sun, Qiu-Ning

2010-03-01

Laugier-Hunziker syndrome (LHS), a rare, acquired pigmentary disorder of the lips, oral mucosa, and fingers, is known to be an entirely benign disease with no systemic manifestations. In the past, the pigmentation has been treated efficiently in a few patients with the Q-switched neodymium: yttrium-aluminum-garnet (Nd:YAG) laser and the Q-switched alexandrite laser (QSAL). In order to evaluate the efficacy and safety of QSAL on Chinese patients of LHS, we treated 22 patients with QSAL in the past 5 years. Treatments were delivered on a bimonthly or trimonthly basis until the abnormal pigmentation totally disappeared. Patients were evaluated at each visit for evidence of dyspigmentation, scarring, or other untoward effects from the laser treatment. Our 22 subjects consisted of 18 females and 4 males with a mean age of 42.4 years. After only one session of laser treatment, the clearing on the lips was as follow: 18 (81.8%) excellent, 2 (9.1%) good, 1 (4.5%) fair and 1 (4.5%) poor. Eighteen patients (81.8%) with LHS, who had achieved excellent clearing after only one session of laser treatment, did not receive further treatment. Among the left four patients, three patients (13.6%) achieved complete results after three laser treatments. Only one patient required six sessions to achieve complete clearance. No scarring was noted after any of the treatments. The appearance of pigmentation on mucous membranes in a middle-aged patient without a significant family history for skin disorders should prompt consideration for the possible diagnosis of LHS. Our study has also demonstrated QSAL to be highly effective and safe in the treatment of LHS.

Fixing clearance as early as lead optimization using high throughput in vitro incubations in combination with exact mass detection and automatic structure elucidation of metabolites.

PubMed

Zimmerlin, Alfred; Kiffe, Michael

2013-01-01

New enabling MS technologies have made it possible to elucidate metabolic pathways present in ex vivo (blood, bile and/or urine) or in vitro (liver microsomes, hepatocytes and/or S9) samples. When investigating samples from high throughput assays the challenge that the user is facing now is to extract the appropriate information and compile it so that it is understandable to all. Medicinal chemist may then design the next generation of (better) drug candidates combining the needs for potency and metabolic stability and their synthetic creativity. This review focuses on the comparison of these enabling MS technologies and the IT tools developed for their interpretation.

Turbine-blade tip clearance and tip timing measurements using an optical fiber bundle sensor

NASA Astrophysics Data System (ADS)

Garcia, Iker; Beloki, Josu; Zubia, Joseba; Durana, Gaizka; Aldabaldetreku, Gotzon

2013-04-01

Traditional limitations of capacitive, inductive or discharging probe sensor for tip timing and tip clearance measurements are overcome by reflective intensity modulated optical fiber sensors. This paper presents the signals and results corresponding to a one stage turbine rig which rotor has 146 blades, obtained from a transonic wind-tunnel test. The probe is based on a trifurcated bundle of optical fibers that is mounted on turbine casing. It is composed of a central illuminating fiber that guides the light from a laser to the turbine blade, and two concentric rings of receiving fibers that collect the reflected light. Two photodetectors turn this reflected light signal from the receiving rings into voltage. The electrical signals are acquired and saved by a high-sample-rate oscilloscope. In tip clearance calculations the ratio of the signals provided by each ring of receiving fibers is evaluated and translated into distance. In the case of tip timing measurements, only one of the signals is considered to get the arrival time of the blade. The differences between the real and theoretical arrival times of the blades are used to obtain the deflections amplitude. The system provides the travelling wave spectrum, which presents the average vibration amplitude of the blades at a certain nodal diameter. The reliability of the results in the turbine rig testing facilities suggests the possibility of performing these measurements in real turbines under real working conditions.

Skin glucose metabolism and microvascular blood flow during local insulin delivery and after an oral glucose load.

PubMed

Iredahl, Fredrik; Högstedt, Alexandra; Henricson, Joakim; Sjöberg, Folke; Tesselaar, Erik; Farnebo, Simon

2016-10-01

Insulin causes capillary recruitment in muscle and adipose tissue, but the metabolic and microvascular effects of insulin in the skin have not been studied in detail. The aim of this study was to measure glucose metabolism and microvascular blood flow in the skin during local insulin delivery and after an oral glucose load. Microdialysis catheters were inserted intracutanously in human subjects. In eight subjects two microdialysis catheters were inserted, one perfused with insulin and one with control solution. First the local effects of insulin was studied, followed by a systemic provocation by an oral glucose load. Additionally, as control experiment, six subjects did not recieve local delivery of insulin or the oral glucose load. During microdialysis the local blood flow was measured by urea clearance and by laser speckle contrast imaging (LSCI). Within 15 minutes of local insulin delivery, microvascular blood flow in the skin increased (urea clearance: P=.047, LSCI: P=.002) paralleled by increases in pyruvate (P=.01) and lactate (P=.04), indicating an increase in glucose uptake. An oral glucose load increased urea clearance from the catheters, indicating an increase in skin perfusion, although no perfusion changes were detected with LSCI. The concentration of glucose, pyruvate and lactate increased in the skin after the oral glucose load. Insulin has metabolic and vasodilatory effects in the skin both when given locally and after systemic delivery through an oral glucose load. © 2016 John Wiley & Sons Ltd.

L-arginine reverses alterations in drug disposition induced by spinal cord injury by increasing hepatic blood flow.

PubMed

Vertiz-Hernandez, Antonio; Castaneda-Hernandez, Gilberto; Martinez-Cruz, Angelina; Cruz-Antonio, Leticia; Grijalva, Israel; Guizar-Sahagun, Gabriel

2007-12-01

High hepatic extraction drugs--such as phenacetin, methylprednisolone, and cyclosporine--exhibit an increased bioavailability after acute spinal cord injury (SCI) due to an impaired clearance. For these drugs, metabolic clearance depends on hepatic blood flow. Thus, it is possible that pharmacokinetic alterations can be reversed by increasing liver perfusion. Therefore, we evaluated the effect of L-arginine, a nitric oxide precursor, on the pharmacokinetics of a prototype drug with high hepatic extraction, and on hepatic microvascular blood flow (MVBF) after acute SCI. Pharmacokinetics of i.v. phenacetin was studied in rats 24 h after a severe T-5 spinal cord contusion; animals being pretreated with L-arginine 100 mg/kg i.v. or vehicle. MVBF was assessed under similar experimental conditions using laser Doppler flowmetry. SCI significantly altered phenacetin pharmacokinetics. Clearance was significantly reduced, resulting in a prolonged half-life and an increase in bioavailability, while volume of distribution was decreased. Pharmacokinetic alterations were reversed when injured rats were pretreated with L -arginine. It was also observed that L-arginine significantly increased hepatic MVBF in injured rats, notwithstanding it exhibited a limited effect on sham-injured animals. Our data hence suggest that L-arginine is able to reverse SCI-induced alterations in phenacetin pharmacokinetics due to an impaired hepatic MVBF, likely by increased nitric oxide synthesis leading to vasodilation. Further studies are warranted to examine the potential usefulness of nitric oxide supplementation in a clinical setting.

Combined multiphoton imaging and automated functional enucleation of porcine oocytes using femtosecond laser pulses

NASA Astrophysics Data System (ADS)

Kuetemeyer, Kai; Lucas-Hahn, Andrea; Petersen, Bjoern; Lemme, Erika; Hassel, Petra; Niemann, Heiner; Heisterkamp, Alexander

2010-07-01

Since the birth of ``Dolly'' as the first mammal cloned from a differentiated cell, somatic cell cloning has been successful in several mammalian species, albeit at low success rates. The highly invasive mechanical enucleation step of a cloning protocol requires sophisticated, expensive equipment and considerable micromanipulation skill. We present a novel noninvasive method for combined oocyte imaging and automated functional enucleation using femtosecond (fs) laser pulses. After three-dimensional imaging of Hoechst-labeled porcine oocytes by multiphoton microscopy, our self-developed software automatically identified the metaphase plate. Subsequent irradiation of the metaphase chromosomes with the very same laser at higher pulse energies in the low-density-plasma regime was used for metaphase plate ablation (functional enucleation). We show that fs laser-based functional enucleation of porcine oocytes completely inhibited the parthenogenetic development without affecting the oocyte morphology. In contrast, nonirradiated oocytes were able to develop parthenogenetically to the blastocyst stage without significant differences to controls. Our results indicate that fs laser systems have great potential for oocyte imaging and functional enucleation and may improve the efficiency of somatic cell cloning.

Closed-loop wavelength stabilization of an optical parametric oscillator as a front end of a high-power iodine laser chain.

PubMed

Kral, L

2007-05-01

We present a complex stabilization and control system for a commercially available optical parametric oscillator. The system is able to stabilize the oscillator's output wavelength at a narrow spectral line of atomic iodine with subpicometer precision, allowing utilization of this solid-state parametric oscillator as a front end of a high-power photodissociation laser chain formed by iodine gas amplifiers. In such setup, a precise wavelength matching between the front end and the amplifier chain is necessary due to extremely narrow spectral lines of the gaseous iodine (approximately 20 pm). The system is based on a personal computer, a heated iodine cell, and a few other low-cost components. It automatically identifies the proper peak within the iodine absorption spectrum, and then keeps the oscillator tuned to this peak with high precision and reliability. The use of the solid-state oscillator as the front end allows us to use the whole iodine laser system as a pump laser for the optical parametric chirped pulse amplification, as it enables precise time synchronization with a signal Ti:sapphire laser.

Coherent infrared radiation from the ALS generated via femtosecond laser modulation of the electron beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Byrd, J.M.; Hao, Z.; Martin, M.C.

2004-07-01

Interaction of an electron beam with a femtosecond laser pulse co-propagating through a wiggler at the ALS produces large modulation of the electron energies within a short {approx}100 fs slice of the electron bunch. Propagating around the storage ring, this bunch develops a longitudinal density perturbation due to the dispersion of electron trajectories. The length of the perturbation evolves with a distance from the wiggler but is much shorter than the electron bunch length. This perturbation causes the electron bunch to emit short pulses of temporally and spatially coherent infrared light which are automatically synchronized to the modulating laser. Themore » intensity and spectra of the infrared light were measured in two storage ring locations for a nominal ALS lattice and for an experimental lattice with the higher momentum compaction factor. The onset of instability stimulated by laser e-beam interaction had been discovered. The infrared signal is now routinely used as a sensitive monitor for a fine tuning of the laser beam alignment during data accumulation in the experiments with femtosecond x-ray pulses.« less

Optoelectronic imaging of speckle using image processing method

NASA Astrophysics Data System (ADS)

Wang, Jinjiang; Wang, Pengfei

2018-01-01

A detailed image processing of laser speckle interferometry is proposed as an example for the course of postgraduate student. Several image processing methods were used together for dealing with optoelectronic imaging system, such as the partial differential equations (PDEs) are used to reduce the effect of noise, the thresholding segmentation also based on heat equation with PDEs, the central line is extracted based on image skeleton, and the branch is removed automatically, the phase level is calculated by spline interpolation method, and the fringe phase can be unwrapped. Finally, the imaging processing method was used to automatically measure the bubble in rubber with negative pressure which could be used in the tire detection.

A robust and hierarchical approach for the automatic co-registration of intensity and visible images

NASA Astrophysics Data System (ADS)

González-Aguilera, Diego; Rodríguez-Gonzálvez, Pablo; Hernández-López, David; Luis Lerma, José

2012-09-01

This paper presents a new robust approach to integrate intensity and visible images which have been acquired with a terrestrial laser scanner and a calibrated digital camera, respectively. In particular, an automatic and hierarchical method for the co-registration of both sensors is developed. The approach integrates several existing solutions to improve the performance of the co-registration between range-based and visible images: the Affine Scale-Invariant Feature Transform (A-SIFT), the epipolar geometry, the collinearity equations, the Groebner basis solution and the RANdom SAmple Consensus (RANSAC), integrating a voting scheme. The approach presented herein improves the existing co-registration approaches in automation, robustness, reliability and accuracy.

Application of optoelectronic sensors for precise, automatic monitoring of vibration, tilt, and deformation of building subjected to static and dynamic effects of the environment

NASA Astrophysics Data System (ADS)

Bochenek, Wojciech; Passia, Henryk; Szade, Adam

2003-09-01

A measuring system composed of optoelectronic and electronic sensors was constructed. These are: laser tilt sensor (CMI- developed), acceleration sensor, and the one to measure the propagation fissures. They are characterized by high precision of measurement, combined with automatic, multichannel data acquisition. These assemblies of sensors are installed in the buildings and industrial structures such as: churches, hospitals, chimneys, bridges, towers, apartment buildings for which particular protection is needed because of adverse impacts of environmental agents such as mining, water and climatic conditions. The paper presents examples of application, illustrated by the most interesting results of measurements.

Automatic classification of bottles in crates

NASA Astrophysics Data System (ADS)

Aas, Kjersti; Eikvil, Line; Bremnes, Dag; Norbryhn, Andreas

1995-03-01

This paper presents a statistical method for classification of bottles in crates for use in automatic return bottle machines. For the automatons to reimburse the correct deposit, a reliable recognition is important. The images are acquired by a laser range scanner coregistering the distance to the object and the strength of the reflected signal. The objective is to identify the crate and the bottles from a library with a number of legal types. The bottles with significantly different size are separated using quite simple methods, while a more sophisticated recognizer is required to distinguish the more similar bottle types. Good results have been obtained when testing the method developed on bottle types which are difficult to distinguish using simple methods.

Three-dimensional imaging and remote sensing imaging; Proceedings of the Meeting, Los Angeles, CA, Jan. 14, 15, 1988

NASA Astrophysics Data System (ADS)

Robbins, Woodrow E.

1988-01-01

The present conference discusses topics in novel technologies and techniques of three-dimensional imaging, human factors-related issues in three-dimensional display system design, three-dimensional imaging applications, and image processing for remote sensing. Attention is given to a 19-inch parallactiscope, a chromostereoscopic CRT-based display, the 'SpaceGraph' true three-dimensional peripheral, advantages of three-dimensional displays, holographic stereograms generated with a liquid crystal spatial light modulator, algorithms and display techniques for four-dimensional Cartesian graphics, an image processing system for automatic retina diagnosis, the automatic frequency control of a pulsed CO2 laser, and a three-dimensional display of magnetic resonance imaging of the spine.

Extracting the distribution of laser damage precursors on fused silica surfaces for 351 nm, 3 ns laser pulses at high fluences (20-150 J/cm2).

PubMed

Laurence, Ted A; Bude, Jeff D; Ly, Sonny; Shen, Nan; Feit, Michael D

2012-05-07

Surface laser damage limits the lifetime of optics for systems guiding high fluence pulses, particularly damage in silica optics used for inertial confinement fusion-class lasers (nanosecond-scale high energy pulses at 355 nm/3.5 eV). The density of damage precursors at low fluence has been measured using large beams (1-3 cm); higher fluences cannot be measured easily since the high density of resulting damage initiation sites results in clustering. We developed automated experiments and analysis that allow us to damage test thousands of sites with small beams (10-30 µm), and automatically image the test sites to determine if laser damage occurred. We developed an analysis method that provides a rigorous connection between these small beam damage test results of damage probability versus laser pulse energy and the large beam damage results of damage precursor densities versus fluence. We find that for uncoated and coated fused silica samples, the distribution of precursors nearly flattens at very high fluences, up to 150 J/cm2, providing important constraints on the physical distribution and nature of these precursors.

Research on the laser transmission characteristics simulation and comprehensive test in complex channel environment

NASA Astrophysics Data System (ADS)

Fu, Qiang; Liu, Jianhua; Wang, Xiaoman; Jiang, Huilin; Liu, Zhi

2014-12-01

The laser transmission characteristics affected in the complex channel environment, which limits the performance of laser equipment and engineering application severely. The article aim at the influence of laser transmission in atmospheric and seawater channels, summarizes the foreign researching work of the simulation and comprehensive test regarding to the laser transmission characteristics in complex environment. And researched the theory of atmospheric turbulence effect, water attenuation features, and put forward the corresponding theoretical model. And researched the simulate technology of atmospheric channel and sea water channel, put forward the analog device plan, adopt the similar theory of flowing to simulate the atmosphere turbulence .When the flowing has the same condition of geometric limits including the same Reynolds, they must be similar to each other in the motivation despite of the difference in the size, speed, and intrinsic quality. On this basis, set up a device for complex channel simulation and comprehensive testing, the overall design of the structure of the device, Hot and Cold Air Convection Simulation of Atmospheric Turbulence, mainly consists of cell body, heating systems, cooling systems, automatic control system. he simulator provides platform and method for the basic research of laser transmission characteristics in the domestic.

A Medical Manipulator System with Lasers in Photodynamic Therapy of Port Wine Stains

PubMed Central

Wang, Xingtao; Tian, Chunlai; Duan, Xingguang; Gu, Ying; Huang, Naiyan

2014-01-01

Port wine stains (PWS) are a congenital malformation and dilation of the superficial dermal capillary. Photodynamic therapy (PDT) with lasers is an effective treatment of PWS with good results. However, because the laser density is uneven and nonuniform, the treatment is carried out manually by a doctor thus providing little accuracy. Additionally, since the treatment of a single lesion can take between 30 and 60 minutes, the doctor can become fatigued after only a few applications. To assist the medical staff with this treatment method, a medical manipulator system (MMS) was built to operate the lasers. The manipulator holds the laser fiber and, using a combination of active and passive joints, the fiber can be operated automatically. In addition to the control input from the doctor over a human-computer interface, information from a binocular vision system is used to guide and supervise the operation. Clinical results are compared in nonparametric values between treatments with and without the use of the MMS. The MMS, which can significantly reduce the workload of doctors and improve the uniformity of laser irradiation, was safely and helpfully applied in PDT treatment of PWS with good therapeutic results. PMID:25302297

Surface imaging, laser positioning or volumetric imaging for breast cancer with nodal involvement treated by helical TomoTherapy.

PubMed

Crop, Frederik; Pasquier, David; Baczkiewic, Amandine; Doré, Julie; Bequet, Lena; Steux, Emeline; Gadroy, Anne; Bouillon, Jacqueline; Florence, Clement; Muszynski, Laurence; Lacour, Mathilde; Lartigau, Eric

2016-09-08

A surface imaging system, Catalyst (C-Rad), was compared with laser-based positioning and daily mega voltage computed tomography (MVCT) setup for breast patients with nodal involvement treated by helical TomoTherapy. Catalyst-based positioning performed better than laser-based positioning. The respective modalities resulted in a standard deviation (SD), 68% confidence interval (CI) of positioning of left-right, craniocaudal, anterior-posterior, roll: 2.4 mm, 2.7 mm, 2.4 mm, 0.9° for Catalyst positioning, and 6.1 mm, 3.8 mm, 4.9 mm, 1.1° for laser-based positioning, respectively. MVCT-based precision is a combination of the interoperator variability for MVCT fusion and the patient movement during the time it takes for MVCT and fusion. The MVCT fusion interoperator variability for breast patients was evaluated at one SD left-right, craniocaudal, ant-post, roll as: 1.4 mm, 1.8 mm, 1.3 mm, 1.0°. There was no statistically significant difference between the automatic MVCT registration result and the manual adjustment; the automatic fusion results were within the 95% CI of the mean result of 10 users, except for one specific case where the patient was positioned with large yaw. We found that users add variability to the roll correction as the automatic registration was more consistent. The patient position uncertainty confidence interval was evaluated as 1.9 mm, 2.2 mm, 1.6 mm, 0.9° after 4 min, and 2.3 mm, 2.8 mm, 2.2 mm, 1° after 10 min. The combination of this patient movement with MVCT fusion interoperator variability results in total standard deviations of patient posi-tion when treatment starts 4 or 10 min after initial positioning of, respectively: 2.3 mm, 2.8 mm, 2.0 mm, 1.3° and 2.7 mm, 3.3 mm, 2.6 mm, 1.4°. Surface based positioning arrives at the same precision when taking into account the time required for MVCT imaging and fusion. These results can be used on a patient-per-patient basis to decide which positioning system performs the best after the first 5 fractions and when daily MVCT can be omitted. Ideally, real-time monitoring is required to reduce important intrafraction movement. © 2016 The Authors.

Laser Metal Deposition as Repair Technology for Stainless Steel and Titanium Alloys

NASA Astrophysics Data System (ADS)

Graf, Benjamin; Gumenyuk, Andrey; Rethmeier, Michael

In a repair process chain, damaged areas or cracks can be removed by milling and subsequently be reconditioned with new material deposition. The use of laser metal deposition has been investigated for this purpose. The material has been deposited into different groove shapes, using both stainless steel and Ti-6Al-4 V. The influence of welding parameters on the microstructure and the heat affected zone has been studied. The parameters have been modified in order to achieve low heat input and consequently low distortion as well as low metallurgical impact. Finally, an evaluation of the opportunities for an automatized repair process is made.

Phase-amplitude imaging: its application to fully automated analysis of magnetic field measurements in laser-produced plasmas.

PubMed

Kalal, M; Nugent, K A; Luther-Davies, B

1987-05-01

An interferometric technique which enables simultaneous phase and amplitude imaging of optically transparent objects is discussed with respect to its application for the measurement of spontaneous toroidal magnetic fields generated in laser-produced plasmas. It is shown that this technique can replace the normal independent pair of optical systems (interferometry and shadowgraphy) by one system and use computer image processing to recover both the plasma density and magnetic field information with high accuracy. A fully automatic algorithm for the numerical analysis of the data has been developed and its performance demonstrated for the case of simulated as well as experimental data.

Phase-amplitude imaging: its application to fully automated analysis of magnetic field measurements in laser-produced plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kalal, M.; Nugent, K.A.; Luther-Davies, B.

1987-05-01

An interferometric technique which enables simultaneous phase and amplitude imaging of optically transparent objects is discussed with respect to its application for the measurement of spontaneous toroidal magnetic fields generated in laser-produced plasmas. It is shown that this technique can replace the normal independent pair of optical systems (interferometry and shadowgraphy) by one system and use computer image processing to recover both the plasma density and magnetic field information with high accuracy. A fully automatic algorithm for the numerical analysis of the data has been developed and its performance demonstrated for the case of simulated as well as experimental data.

Arduino Due based tool to facilitate in vivo two-photon excitation microscopy.

PubMed

Artoni, Pietro; Landi, Silvia; Sato, Sebastian Sulis; Luin, Stefano; Ratto, Gian Michele

2016-04-01

Two-photon excitation spectroscopy is a powerful technique for the characterization of the optical properties of genetically encoded and synthetic fluorescent molecules. Excitation spectroscopy requires tuning the wavelength of the Ti:sapphire laser while carefully monitoring the delivered power. To assist laser tuning and the control of delivered power, we developed an Arduino Due based tool for the automatic acquisition of high quality spectra. This tool is portable, fast, affordable and precise. It allowed studying the impact of scattering and of blood absorption on two-photon excitation light. In this way, we determined the wavelength-dependent deformation of excitation spectra occurring in deep tissues in vivo.

X-ray online detection for laser welding T-joint of Al-Li alloy

NASA Astrophysics Data System (ADS)

Zhan, Xiaohong; Bu, Xing; Qin, Tao; Yu, Haisong; Chen, Jie; Wei, Yanhong

2017-05-01

In order to detect weld defects in laser welding T-joint of Al-Li alloy, a real-time X-ray image system is set up for quality inspection. Experiments on real-time radiography procedure of the weldment are conducted by using this system. Twin fillet welding seam radiographic arrangement is designed according to the structural characteristics of the weldment. The critical parameters including magnification times, focal length, tube current and tube voltage are studied to acquire high quality weld images. Through the theoretical and data analysis, optimum parameters are settled and expected digital images are captured, which is conductive to automatic defect detection.

Stop-and-Go Mode: Sensor Manipulation as Essential as Sensor Development in Terrestrial Laser Scanning

PubMed Central

Lin, Yi; Hyyppä, Juha; Kukko, Antero

2013-01-01

This study was dedicated to illustrating the significance of sensor manipulation in the case of terrestrial laser scanning, which is a field now in quick development. In fact, this quickness was mainly rooted in the emergence of new sensors with better performance, while the implications of sensor manipulation have not been fully recognized by the whole community. For this technical gap, the stop-and-go mapping mode can be reckoned as one of the potential solution plans. Stop-and-go was first proposed to handle the low efficiency of traditional static terrestrial laser scanning, and then, it was re-emphasized to improve the stability of sample collections for the state-of-the-art technology of mobile laser scanning. This work reviewed the previous efforts of trying the stop-and-go mode for improving the performance of static and mobile terrestrial laser scanning and generalized their principles respectively. This work also analyzed its advantages compared to the fully-static and fully-kinematic terrestrial laser scanning, and suggested the plans with more automatic measures for raising the efficacy of terrestrial laser scanning. Overall, this literature review indicated that the stop-and-go mapping mode as a case with generic sense can verify the presumption of sensor manipulation as essential as sensor development. PMID:23799493

Infrared techniques for detecting carbonization at onset of device failure

NASA Astrophysics Data System (ADS)

Farr, Norman; Sinofsky, Edward L.

1997-05-01

We describe the design, and development of an infrared detection system which detects the onset of carbonization of fluoropolymers in the presence of up to 60 watts of 1.06 micrometer laser energy. This system is used to shut down a therapeutic laser system before significant damage is done to a laser delivery device and patient. Black body radiation emitting from the diffusion tip is transmitted, backwards, through the same optical fiber as the therapeutic wavelength. Using a high power 1.06 micrometer laser mirror at 45 degrees, most of the 1.06 micrometer light is reflected while the black body radiation is passed to a holographic notch filter which further filters the signal. Still more filtering was needed before the 1.1 to 2 micrometer signal could be detected within the presence the therapeutic light using an extended indium gallium arsenide photodetector. There was still a significant detected offset which increased with laser power which necessitated a means to automatically null the offset for different laser power settings. The system is designed to be used with any unmodified laser system. It interfaces directly to or in series with most common external safety interlocks and can be used with various diffusing tips, probes or bare fibers.

Optimizing laser crater enhanced Raman spectroscopy.

PubMed

Lednev, V N; Sdvizhenskii, P A; Grishin, M Ya; Filichkina, V A; Shchegolikhin, A N; Pershin, S M

2018-03-20

Raman signal enhancement by laser crater production was systematically studied for 785 nm continuous wave laser pumping. Laser craters were produced in L-aspartic acid powder by a nanosecond pulsed solid state neodymium-doped yttrium aluminum garnet laser (532 nm, 8 ns, 1 mJ/pulse), while Raman spectra were then acquired by using a commercial spectrometer with 785 nm laser beam pumping. The Raman signal enhancement effect was studied in terms of the number of ablating pulses used, the lens-to-sample distance, and the crater-center-laser-spot offset. The influence of the experiment parameters on Raman signal enhancement was studied for different powder materials. Maximum Raman signal enhancement reached 11 fold for loose powders but decreased twice for pressed tablets. Raman signal enhancement was demonstrated for several diverse powder materials like gypsum or ammonium nitrate with better results achieved for the samples tending to give narrow and deep craters upon the laser ablation stage. Alternative ways of cavity production (steel needle tapping and hole drilling) were compared with the laser cratering technique in terms of Raman signal enhancement. Drilling was found to give the poorest enhancement of the Raman signal, while both laser ablation and steel needle tapping provided comparable results. Here, we have demonstrated for the first time, to the best of our knowledge, that a Raman signal can be enhanced 10 fold with the aid of simple cavity production by steel needle tapping in rough highly reflective materials. Though laser crater enhancement Raman spectroscopy requires an additional pulsed laser, this technique is more appropriate for automatization compared to the needle tapping approach.

Toward automated selective retina treatment (SRT): an optical microbubble detection technique

NASA Astrophysics Data System (ADS)

Seifert, Eric; Park, Young-Gun; Theisen-Kunde, Dirk; Roh, Young-Jung; Brinkmann, Ralf

2018-02-01

Selective retina therapy (SRT) is an ophthalmological laser technique, targeting the retinal pigment epithelium (RPE) with repetitive microsecond laser pulses, while causing no thermal damage to the neural retina, the photoreceptors as well as the choroid. The RPE cells get damaged mechanically by microbubbles originating, at the intracellular melanosomes. Beneficial effects of SRT on Central Serous Retinopathy (CSR) and Diabetic Macula Edema (DME) have already been shown. Variations in the transmission of the anterior eye media and pigmentation variation of RPE yield in intra- and inter- individual thresholds of the pulse energy required for selective RPE damage. Those selective RPE lesions are not visible. Thus, dosimetry-systems, designed to detect microbubbles as an indicator for RPE cell damage, are demanded elements to facilitate SRT application. Therefore, a technique based on the evaluation of backscattered treatment light has been developed. Data of 127 spots, acquired during 10 clinical treatments of CSR patients, were assigned to a RPE cell damage class, validated by fluorescence angiography (FLA). An algorithm has been designed to match the FLA based information. A sensitivity of 0.9 with a specificity close to 1 is achieved. The data can be processed within microseconds. Thus, the process can be implemented in existing SRT lasers with an automatic pulse wise increasing energy and an automatic irradiation ceasing ability to enable automated treatment close above threshold to prevent adverse effects caused by too high pulse energy. Alternatively, a guidance procedure, informing the treating clinician about the adequacy of the actual settings, is possible.

Tracking scanning laser ophthalmoscope (TSLO)

NASA Astrophysics Data System (ADS)

Hammer, Daniel X.; Ferguson, R. Daniel; Magill, John C.; White, Michael A.; Elsner, Ann E.; Webb, Robert H.

2003-07-01

The effectiveness of image stabilization with a retinal tracker in a multi-function, compact scanning laser ophthalmoscope (TSLO) was demonstrated in initial human subject tests. The retinal tracking system uses a confocal reflectometer with a closed loop optical servo system to lock onto features in the fundus. The system is modular to allow configuration for many research and clinical applications, including hyperspectral imaging, multifocal electroretinography (MFERG), perimetry, quantification of macular and photo-pigmentation, imaging of neovascularization and other subretinal structures (drusen, hyper-, and hypo-pigmentation), and endogenous fluorescence imaging. Optical hardware features include dual wavelength imaging and detection, integrated monochromator, higher-order motion control, and a stimulus source. The system software consists of a real-time feedback control algorithm and a user interface. Software enhancements include automatic bias correction, asymmetric feature tracking, image averaging, automatic track re-lock, and acquisition and logging of uncompressed images and video files. Normal adult subjects were tested without mydriasis to optimize the tracking instrumentation and to characterize imaging performance. The retinal tracking system achieves a bandwidth of greater than 1 kHz, which permits tracking at rates that greatly exceed the maximum rate of motion of the human eye. The TSLO stabilized images in all test subjects during ordinary saccades up to 500 deg/sec with an inter-frame accuracy better than 0.05 deg. Feature lock was maintained for minutes despite subject eye blinking. Successful frame averaging allowed image acquisition with decreased noise in low-light applications. The retinal tracking system significantly enhances the imaging capabilities of the scanning laser ophthalmoscope.

An open source digital servo for atomic, molecular, and optical physics experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leibrandt, D. R., E-mail: david.leibrandt@nist.gov; Heidecker, J.

2015-12-15

We describe a general purpose digital servo optimized for feedback control of lasers in atomic, molecular, and optical physics experiments. The servo is capable of feedback bandwidths up to roughly 1 MHz (limited by the 320 ns total latency); loop filter shapes up to fifth order; multiple-input, multiple-output control; and automatic lock acquisition. The configuration of the servo is controlled via a graphical user interface, which also provides a rudimentary software oscilloscope and tools for measurement of system transfer functions. We illustrate the functionality of the digital servo by describing its use in two example scenarios: frequency control of themore » laser used to probe the narrow clock transition of {sup 27}Al{sup +} in an optical atomic clock, and length control of a cavity used for resonant frequency doubling of a laser.« less

An open source digital servo for atomic, molecular, and optical physics experiments.

PubMed

Leibrandt, D R; Heidecker, J

2015-12-01

We describe a general purpose digital servo optimized for feedback control of lasers in atomic, molecular, and optical physics experiments. The servo is capable of feedback bandwidths up to roughly 1 MHz (limited by the 320 ns total latency); loop filter shapes up to fifth order; multiple-input, multiple-output control; and automatic lock acquisition. The configuration of the servo is controlled via a graphical user interface, which also provides a rudimentary software oscilloscope and tools for measurement of system transfer functions. We illustrate the functionality of the digital servo by describing its use in two example scenarios: frequency control of the laser used to probe the narrow clock transition of (27)Al(+) in an optical atomic clock, and length control of a cavity used for resonant frequency doubling of a laser.

Auto-calibrated scanning-angle prism-type total internal reflection microscopy for nanometer-precision axial position determination and optional variable-illumination-depth pseudo total internal reflection microscopy

DOEpatents

Fang, Ning; Sun, Wei

2015-04-21

A method, apparatus, and system for improved VA-TIRFM microscopy. The method comprises automatically controlled calibration of one or more laser sources by precise control of presentation of each laser relative a sample for small incremental changes of incident angle over a range of critical TIR angles. The calibration then allows precise scanning of the sample for any of those calibrated angles for higher and more accurate resolution, and better reconstruction of the scans for super resolution reconstruction of the sample. Optionally the system can be controlled for incident angles of the excitation laser at sub-critical angles for pseudo TIRFM. Optionally both above-critical angle and sub critical angle measurements can be accomplished with the same system.

Semantic Labelling of Road Furniture in Mobile Laser Scanning Data

NASA Astrophysics Data System (ADS)

Li, F.; Oude Elberink, S.; Vosselman, G.

2017-09-01

Road furniture semantic labelling is vital for large scale mapping and autonomous driving systems. Much research has been investigated on road furniture interpretation in both 2D images and 3D point clouds. Precise interpretation of road furniture in mobile laser scanning data still remains unexplored. In this paper, a novel method is proposed to interpret road furniture based on their logical relations and functionalities. Our work represents the most detailed interpretation of road furniture in mobile laser scanning data. 93.3 % of poles are correctly extracted and all of them are correctly recognised. 94.3 % of street light heads are detected and 76.9 % of them are correctly identified. Despite errors arising from the recognition of other components, our framework provides a promising solution to automatically map road furniture at a detailed level in urban environments.

Multi-channel automotive night vision system

NASA Astrophysics Data System (ADS)

Lu, Gang; Wang, Li-jun; Zhang, Yi

2013-09-01

A four-channel automotive night vision system is designed and developed .It is consist of the four active near-infrared cameras and an Mulit-channel image processing display unit,cameras were placed in the automobile front, left, right and rear of the system .The system uses near-infrared laser light source，the laser light beam is collimated, the light source contains a thermoelectric cooler (TEC),It can be synchronized with the camera focusing, also has an automatic light intensity adjustment, and thus can ensure the image quality. The principle of composition of the system is description in detail,on this basis, beam collimation,the LD driving and LD temperature control of near-infrared laser light source,four-channel image processing display are discussed.The system can be used in driver assistance, car BLIS, car parking assist system and car alarm system in day and night.

Semiconductor laser self-mixing micro-vibration measuring technology based on Hilbert transform

NASA Astrophysics Data System (ADS)

Tao, Yufeng; Wang, Ming; Xia, Wei

2016-06-01

A signal-processing synthesizing Wavelet transform and Hilbert transform is employed to measurement of uniform or non-uniform vibrations in self-mixing interferometer on semiconductor laser diode with quantum well. Background noise and fringe inclination are solved by decomposing effect, fringe counting is adopted to automatic determine decomposing level, a couple of exact quadrature signals are produced by Hilbert transform to extract vibration. The tempting potential of real-time measuring micro vibration with high accuracy and wide dynamic response bandwidth using proposed method is proven by both simulation and experiment. Advantages and error sources are presented as well. Main features of proposed semiconductor laser self-mixing interferometer are constant current supply, high resolution, simplest optical path and much higher tolerance to feedback level than existing self-mixing interferometers, which is competitive for non-contact vibration measurement.

An open source digital servo for atomic, molecular, and optical physics experiments

NASA Astrophysics Data System (ADS)

Leibrandt, D. R.; Heidecker, J.

2015-12-01

We describe a general purpose digital servo optimized for feedback control of lasers in atomic, molecular, and optical physics experiments. The servo is capable of feedback bandwidths up to roughly 1 MHz (limited by the 320 ns total latency); loop filter shapes up to fifth order; multiple-input, multiple-output control; and automatic lock acquisition. The configuration of the servo is controlled via a graphical user interface, which also provides a rudimentary software oscilloscope and tools for measurement of system transfer functions. We illustrate the functionality of the digital servo by describing its use in two example scenarios: frequency control of the laser used to probe the narrow clock transition of 27Al+ in an optical atomic clock, and length control of a cavity used for resonant frequency doubling of a laser.

An open source digital servo for atomic, molecular, and optical physics experiments

PubMed Central

Leibrandt, D. R.; Heidecker, J.

2016-01-01

We describe a general purpose digital servo optimized for feedback control of lasers in atomic, molecular, and optical physics experiments. The servo is capable of feedback bandwidths up to roughly 1 MHz (limited by the 320 ns total latency); loop filter shapes up to fifth order; multiple-input, multiple-output control; and automatic lock acquisition. The configuration of the servo is controlled via a graphical user interface, which also provides a rudimentary software oscilloscope and tools for measurement of system transfer functions. We illustrate the functionality of the digital servo by describing its use in two example scenarios: frequency control of the laser used to probe the narrow clock transition of 27Al+ in an optical atomic clock, and length control of a cavity used for resonant frequency doubling of a laser. PMID:26724014

Maintaining a stationary laser footprint during angular scan in internal-reflection experiments.

PubMed

Fontana, Eduardo; Cavalcanti, Gustavo Oliveira

2013-11-10

In internal-reflection metrology using prisms, the prism is usually mounted on a rotation/translation stage to enable adjusting angle and location of the laser footprint on the surface. If a visual inspection method is used to find the laser footprint, the task becomes impossible if invisible radiation in the near infrared is employed. In addition, it may be desirable to perform angular scan experiments with a stationary footprint on the surface during scans, or even to automatically probe specific points on an extended prism face for predetermined incidence angles. In this paper, a formulation is developed to determine the required translation along the prism face to allow maintaining the laser footprint stationary under a given rotation. A web-based app developed under the scope of this work demonstrates the applicability of the approach for silica, BK7 and SF2 glasses, in the wavelength range from 500 to 1500 nm and for an arbitrary geometry of the glass prism.

Fragment size distribution statistics in dynamic fragmentation of laser shock-loaded tin

NASA Astrophysics Data System (ADS)

He, Weihua; Xin, Jianting; Zhao, Yongqiang; Chu, Genbai; Xi, Tao; Shui, Min; Lu, Feng; Gu, Yuqiu

2017-06-01

This work investigates the geometric statistics method to characterize the size distribution of tin fragments produced in the laser shock-loaded dynamic fragmentation process. In the shock experiments, the ejection of the tin sample with etched V-shape groove in the free surface are collected by the soft recovery technique. Subsequently, the produced fragments are automatically detected with the fine post-shot analysis techniques including the X-ray micro-tomography and the improved watershed method. To characterize the size distributions of the fragments, a theoretical random geometric statistics model based on Poisson mixtures is derived for dynamic heterogeneous fragmentation problem, which reveals linear combinational exponential distribution. The experimental data related to fragment size distributions of the laser shock-loaded tin sample are examined with the proposed theoretical model, and its fitting performance is compared with that of other state-of-the-art fragment size distribution models. The comparison results prove that our proposed model can provide far more reasonable fitting result for the laser shock-loaded tin.

A study on new method of noninvasive esophageal venous pressure measurement based on the airflow and laser detection technology.

PubMed

Hu, Chenghuan; Huang, Feizhou; Zhang, Rui; Zhu, Shaihong; Nie, Wanpin; Liu, Xunyang; Liu, Yinglong; Li, Peng

2015-01-01

Using optics combined with automatic control and computer real-time image detection technology, a novel noninvasive method of noncontact pressure manometry was developed based on the airflow and laser detection technology in this study. The new esophageal venous pressure measurement system was tested in-vitro experiments. A stable and adjustable pulse stream was produced from a self-developed pump and a laser emitting apparatus could generate optical signals which can be captured by image acquisition and analysis system program. A synchronization system simultaneous measured the changes of air pressure and the deformation of the vein wall to capture the vascular deformation while simultaneously record the current pressure value. The results of this study indicated that the pressure values tested by the new method have good correlation with the actual pressure value in animal experiments. The new method of noninvasive pressure measurement based on the airflow and laser detection technology is accurate, feasible, repeatable and has a good application prospects.

Laser profiling of 3D microturbine blades

NASA Astrophysics Data System (ADS)

Holmes, Andrew S.; Heaton, Mark E.; Hong, Guodong; Pullen, Keith R.; Rumsby, Phil T.

2003-11-01

We have used KrF excimer laser ablation in the fabrication of a novel MEMS power conversion device based on an axial-flow turbine with an integral axial-flux electromagnetic generator. The device has a sandwich structure, comprising a pair of silicon stators either side of an SU8 polymer rotor. The curved turbine rotor blades were fabricated by projection ablation of SU8 parts performed by conventional UV lithography. A variable aperture mask, implemented by stepping a moving aperture in front of a fixed one, was used to achieve the desired spatial variation in the ablated depth. An automatic process was set up on a commercial laser workstation, with the laser firing and mask motion being controlled by computer. High quality SU8 rotor parts with diameters of 13 mm and depths of 1 mm were produced at a fluence of 0.7 J/cm2, corresponding to a material removal rate of approximately 0.3 μm per pulse. A similar approach was used to form SU8 guide vane inserts for the stators.

Research of infrared laser based pavement imaging and crack detection

NASA Astrophysics Data System (ADS)

Hong, Hanyu; Wang, Shu; Zhang, Xiuhua; Jing, Genqiang

2013-08-01

Road crack detection is seriously affected by many factors in actual applications, such as some shadows, road signs, oil stains, high frequency noise and so on. Due to these factors, the current crack detection methods can not distinguish the cracks in complex scenes. In order to solve this problem, a novel method based on infrared laser pavement imaging is proposed. Firstly, single sensor laser pavement imaging system is adopted to obtain pavement images, high power laser line projector is well used to resist various shadows. Secondly, the crack extraction algorithm which has merged multiple features intelligently is proposed to extract crack information. In this step, the non-negative feature and contrast feature are used to extract the basic crack information, and circular projection based on linearity feature is applied to enhance the crack area and eliminate noise. A series of experiments have been performed to test the proposed method, which shows that the proposed automatic extraction method is effective and advanced.

Alignment system for SGII-Up laser facility

NASA Astrophysics Data System (ADS)

Gao, Yanqi; Cui, Yong; Li, Hong; Gong, Lei; Lin, Qiang; Liu, Daizhong; Zhu, Baoqiang; Ma, Weixin; Zhu, Jian; Lin, Zunqi

2018-03-01

The SGII-Up laser facility in Shanghai is one of the most important high-power laser facilities in China. It is designed to obtain 24 kJ (3ω) of energy with a square pulse of 3 ns using eight laser beams (two bundles). To satisfy the requirements for the safety, efficiency, and quality, an alignment system is developed for this facility. This alignment system can perform automatic alignment of the preamplifier system, main amplifier system, and harmonic conversion system within 30 min before every shot during the routine operation of the facility. In this article, an overview of the alignment system is first presented. Then, its alignment characteristics are discussed, along with the alignment process. Finally, experimental results, including the alignment results and the facility performance, are reported. The results show that the far-field beam pointing alignment accuracy is better than 3 μrad, and the alignment error of the near-field beam centering is no larger than 1 mm. These satisfy the design requirements very well.

Automated real-time detection of defects during machining of ceramics

DOEpatents

Ellingson, W.A.; Sun, J.

1997-11-18

Apparatus for the automated real-time detection and classification of defects during the machining of ceramic components employs an elastic optical scattering technique using polarized laser light. A ceramic specimen is continuously moved while being machined. Polarized laser light is directed onto the ceramic specimen surface at a fixed position just aft of the machining tool for examination of the newly machined surface. Any foreign material near the location of the laser light on the ceramic specimen is cleared by an air blast. As the specimen is moved, its surface is continuously scanned by the polarized laser light beam to provide a two-dimensional image presented in real-time on a video display unit, with the motion of the ceramic specimen synchronized with the data acquisition speed. By storing known ``feature masks`` representing various surface and sub-surface defects and comparing measured defects with the stored feature masks, detected defects may be automatically characterized. Using multiple detectors, various types of defects may be detected and classified. 14 figs.

Automated real-time detection of defects during machining of ceramics

DOEpatents

Ellingson, William A.; Sun, Jiangang

1997-01-01

Apparatus for the automated real-time detection and classification of defects during the machining of ceramic components employs an elastic optical scattering technique using polarized laser light. A ceramic specimen is continuously moved while being machined. Polarized laser light is directed onto the ceramic specimen surface at a fixed position just aft of the machining tool for examination of the newly machined surface. Any foreign material near the location of the laser light on the ceramic specimen is cleared by an air blast. As the specimen is moved, its surface is continuously scanned by the polarized laser light beam to provide a two-dimensional image presented in real-time on a video display unit, with the motion of the ceramic specimen synchronized with the data acquisition speed. By storing known "feature masks" representing various surface and sub-surface defects and comparing measured defects with the stored feature masks, detected defects may be automatically characterized. Using multiple detectors, various types of defects may be detected and classified.

Investigation of temperature feedback signal parameters during neoplasms treatment by diode laser radiation

NASA Astrophysics Data System (ADS)

Belikov, Andrey V.; Gelfond, Mark L.; Shatilova, Ksenia V.; Semyashkina, Yulia V.

2016-04-01

Dynamics of temperature signal in operation area and laser power at nevus, papilloma, and keratoma in vivo removal by a 980+/-10 nm diode laser with "blackened" tip operating in continuous (CW) mode and with temperature feedback (APC) mode are presented. Feedback allows maintaining temperature in the area of laser treatment at a preset level by regulating power of diode laser radiation (automatic power control). Temperature in the area of laser treatment was controlled by measuring the amplitude of thermal radiation, which occurs when tissue is heated by laser radiation. Removal of neoplasm was carried out in CW mode with laser radiation average power of 12.5+/-0.5 W; mean temperature in the area of laser treatment was 900+/-10°C for nevus, 800+/-15°C for papilloma, and 850+/-20°C for keratoma. The same laser radiation maximal power (12.5 W) and targeted temperature (900°C) were set for nevus removal in APC mode. The results of investigation are real time oscillograms of the laser power and temperature in the area of laser treatment at neoplasms removal in two described above modes. Simultaneously with the measurement of laser power and the temperature in the area of laser treatment video recording of surgeon manipulations was carried out. We discuss the correlation between the power of the laser radiation, the temperature in the area of laser treatment and consistency of surgeon manipulation. It is shown that the method of removal (excision with or without traction, scanning) influences the temperature in the area of laser treatment. It was found, that at removal of nevus with temperature feedback (APC) mode to achieve comparable with CW mode temperature in the area of laser treatment (900+/-10°C) 20-50% less laser power is required. Consequently, removing these neoplasms in temperature feedback mode can be less traumatic than the removal in CW mode.

Automated grading, upgrading, and cuttings prediction of surfaced dry hardwood lumber

Treesearch

Sang-Mook Lee; Phil Araman; A.Lynn Abbott; Matthew F. Winn

2010-01-01

This paper concerns the scanning, sawing, and grading of kiln-dried hardwood lumber. A prototype system is described that uses laser sources and a video camera to scan boards. The system automatically detects defects and wane, searches for optimal sawing solutions, and then estimates the grades of the boards that would result. The goal is to derive maximum commercial...

Hardwood lumber scanning tests to determine NHLA lumber grades

Treesearch

Philip A. Araman; Ssang-Mook Lee; A. Lynn Abbott; Matthew F. Winn

2011-01-01

This paper concerns the scanning, and grading of kiln-dried hardwood lumber. A prototype system is described that uses laser sources and a video camera to scan boards. The system automatically detects defects and wane, grades the boards, and then searches for higher value boards within the original board. The goal is to derive maximum commercial value based on current...

Automatic Beam Path Analysis of Laser Wakefield Particle Acceleration Data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rubel, Oliver; Geddes, Cameron G.R.; Cormier-Michel, Estelle

2009-10-19

Numerical simulations of laser wakefield particle accelerators play a key role in the understanding of the complex acceleration process and in the design of expensive experimental facilities. As the size and complexity of simulation output grows, an increasingly acute challenge is the practical need for computational techniques that aid in scientific knowledge discovery. To that end, we present a set of data-understanding algorithms that work in concert in a pipeline fashion to automatically locate and analyze high energy particle bunches undergoing acceleration in very large simulation datasets. These techniques work cooperatively by first identifying features of interest in individual timesteps,more » then integrating features across timesteps, and based on the information derived perform analysis of temporally dynamic features. This combination of techniques supports accurate detection of particle beams enabling a deeper level of scientific understanding of physical phenomena than hasbeen possible before. By combining efficient data analysis algorithms and state-of-the-art data management we enable high-performance analysis of extremely large particle datasets in 3D. We demonstrate the usefulness of our methods for a variety of 2D and 3D datasets and discuss the performance of our analysis pipeline.« less

From Laser Scanning to Finite Element Analysis of Complex Buildings by Using a Semi-Automatic Procedure

PubMed Central

Castellazzi, Giovanni; D’Altri, Antonio Maria; Bitelli, Gabriele; Selvaggi, Ilenia; Lambertini, Alessandro

2015-01-01

In this paper, a new semi-automatic procedure to transform three-dimensional point clouds of complex objects to three-dimensional finite element models is presented and validated. The procedure conceives of the point cloud as a stacking of point sections. The complexity of the clouds is arbitrary, since the procedure is designed for terrestrial laser scanner surveys applied to buildings with irregular geometry, such as historical buildings. The procedure aims at solving the problems connected to the generation of finite element models of these complex structures by constructing a fine discretized geometry with a reduced amount of time and ready to be used with structural analysis. If the starting clouds represent the inner and outer surfaces of the structure, the resulting finite element model will accurately capture the whole three-dimensional structure, producing a complex solid made by voxel elements. A comparison analysis with a CAD-based model is carried out on a historical building damaged by a seismic event. The results indicate that the proposed procedure is effective and obtains comparable models in a shorter time, with an increased level of automation. PMID:26225978

Traffic sign detection in MLS acquired point clouds for geometric and image-based semantic inventory

NASA Astrophysics Data System (ADS)

Soilán, Mario; Riveiro, Belén; Martínez-Sánchez, Joaquín; Arias, Pedro

2016-04-01

Nowadays, mobile laser scanning has become a valid technology for infrastructure inspection. This technology permits collecting accurate 3D point clouds of urban and road environments and the geometric and semantic analysis of data became an active research topic in the last years. This paper focuses on the detection of vertical traffic signs in 3D point clouds acquired by a LYNX Mobile Mapper system, comprised of laser scanning and RGB cameras. Each traffic sign is automatically detected in the LiDAR point cloud, and its main geometric parameters can be automatically extracted, therefore aiding the inventory process. Furthermore, the 3D position of traffic signs are reprojected on the 2D images, which are spatially and temporally synced with the point cloud. Image analysis allows for recognizing the traffic sign semantics using machine learning approaches. The presented method was tested in road and urban scenarios in Galicia (Spain). The recall results for traffic sign detection are close to 98%, and existing false positives can be easily filtered after point cloud projection. Finally, the lack of a large, publicly available Spanish traffic sign database is pointed out.

Image-guided biopsy in the esophagus through comprehensive optical frequency domain imaging and laser marking: a study in living swine.

PubMed

Suter, Melissa J; Jillella, Priyanka A; Vakoc, Benjamin J; Halpern, Elkan F; Mino-Kenudson, Mari; Lauwers, Gregory Y; Bouma, Brett E; Nishioka, Norman S; Tearney, Guillermo J

2010-02-01

Random biopsy esophageal surveillance can be subject to sampling errors, resulting in diagnostic uncertainty. Optical frequency domain imaging (OFDI) is a high-speed, 3-dimensional endoscopic microscopy technique. When deployed through a balloon-centering catheter, OFDI can automatically image the entire distal esophagus (6.0 cm length) in approximately 2 minutes. To test a new platform for guided biopsy that allows the operator to select target regions of interest on an OFDI dataset, and then use a laser to mark the esophagus at corresponding locations. The specific goals include determining the optimal laser parameters, testing the accuracy of the laser marking process, evaluating the endoscopic visibility of the laser marks, and assessing the amount of mucosal damage produced by the laser. Experimental study conducted in 5 swine in vivo. Massachusetts General Hospital. Success rate, including endoscopic visibility of laser marks and accuracy of the laser marking process for selected target sites, and extent of the thermal damage caused by the laser marks. All of the laser-induced marks were visible by endoscopy. Target locations were correctly marked with a success rate of 97.07% (95% confidence interval, 89.8%-99.7%). Thermal damage was limited to the superficial layers of the mucosa and was observed to partially heal within 2 days. An animal study with artificially placed targets to simulate pathology. The study demonstrates that laser marking of esophageal sites identified in comprehensive OFDI datasets is feasible and can be performed with sufficient accuracy, precision, and visibility to guide biopsy in vivo.

An automatic tooth preparation technique: A preliminary study

NASA Astrophysics Data System (ADS)

Yuan, Fusong; Wang, Yong; Zhang, Yaopeng; Sun, Yuchun; Wang, Dangxiao; Lyu, Peijun

2016-04-01

The aim of this study is to validate the feasibility and accuracy of a new automatic tooth preparation technique in dental healthcare. An automatic tooth preparation robotic device with three-dimensional motion planning software was developed, which controlled an ultra-short pulse laser (USPL) beam (wavelength 1,064 nm, pulse width 15 ps, output power 30 W, and repeat frequency rate 100 kHz) to complete the tooth preparation process. A total of 15 freshly extracted human intact first molars were collected and fixed into a phantom head, and the target preparation shapes of these molars were designed using customised computer-aided design (CAD) software. The accuracy of tooth preparation was evaluated using the Geomagic Studio and Imageware software, and the preparing time of each tooth was recorded. Compared with the target preparation shape, the average shape error of the 15 prepared molars was 0.05-0.17 mm, the preparation depth error of the occlusal surface was approximately 0.097 mm, and the error of the convergence angle was approximately 1.0°. The average preparation time was 17 minutes. These results validated the accuracy and feasibility of the automatic tooth preparation technique.

An automatic tooth preparation technique: A preliminary study.

PubMed

Yuan, Fusong; Wang, Yong; Zhang, Yaopeng; Sun, Yuchun; Wang, Dangxiao; Lyu, Peijun

2016-04-29

The aim of this study is to validate the feasibility and accuracy of a new automatic tooth preparation technique in dental healthcare. An automatic tooth preparation robotic device with three-dimensional motion planning software was developed, which controlled an ultra-short pulse laser (USPL) beam (wavelength 1,064 nm, pulse width 15 ps, output power 30 W, and repeat frequency rate 100 kHz) to complete the tooth preparation process. A total of 15 freshly extracted human intact first molars were collected and fixed into a phantom head, and the target preparation shapes of these molars were designed using customised computer-aided design (CAD) software. The accuracy of tooth preparation was evaluated using the Geomagic Studio and Imageware software, and the preparing time of each tooth was recorded. Compared with the target preparation shape, the average shape error of the 15 prepared molars was 0.05-0.17 mm, the preparation depth error of the occlusal surface was approximately 0.097 mm, and the error of the convergence angle was approximately 1.0°. The average preparation time was 17 minutes. These results validated the accuracy and feasibility of the automatic tooth preparation technique.

Reproducing the internal and external anatomy of fossil bones: Two new automatic digital tools.

PubMed

Profico, Antonio; Schlager, Stefan; Valoriani, Veronica; Buzi, Costantino; Melchionna, Marina; Veneziano, Alessio; Raia, Pasquale; Moggi-Cecchi, Jacopo; Manzi, Giorgio

2018-04-21

We present two new automatic tools, developed under the R environment, to reproduce the internal and external structures of bony elements. The first method, Computer-Aided Laser Scanner Emulator (CA-LSE), provides the reconstruction of the external portions of a 3D mesh by simulating the action of a laser scanner. The second method, Automatic Segmentation Tool for 3D objects (AST-3D), performs the digital reconstruction of anatomical cavities. We present the application of CA-LSE and AST-3D methods to different anatomical remains, highly variable in terms of shape, size and structure: a modern human skull, a malleus bone, and a Neanderthal deciduous tooth. Both methods are developed in the R environment and embedded in the packages "Arothron" and "Morpho," where both the codes and the data are fully available. The application of CA-LSE and AST-3D allows the isolation and manipulation of the internal and external components of the 3D virtual representation of complex bony elements. In particular, we present the output of the four case studies: a complete modern human endocast and the right maxillary sinus, the dental pulp of the Neanderthal tooth and the inner network of blood vessels of the malleus. Both methods demonstrated to be much faster, cheaper, and more accurate than other conventional approaches. The tools we presented are available as add-ons in existing software within the R platform. Because of ease of application, and unrestrained availability of the methods proposed, these tools can be widely used by paleoanthropologists, paleontologists and anatomists. © 2018 Wiley Periodicals, Inc.

Novel 3-D free-form surface profilometry for reverse engineering

NASA Astrophysics Data System (ADS)

Chen, Liang-Chia; Huang, Zhi-Xue

2005-01-01

This article proposes an innovative 3-D surface contouring approach for automatic and accurate free-form surface reconstruction using a sensor integration concept. The study addresses a critical problem in accurate measurement of free-form surfaces by developing an automatic reconstruction approach. Unacceptable measuring accuracy issues are mainly due to the errors arising from the use of inadequate measuring strategies, ending up with inaccurate digitised data and costly post-data processing in Reverse Engineering (RE). This article is thus aimed to develop automatic digitising strategies for ensuring surface reconstruction efficiency, as well as accuracy. The developed approach consists of two main stages, namely the rapid shape identification (RSI) and the automated laser scanning (ALS) for completing 3-D surface profilometry. This developed approach effectively utilises the advantages of on-line geometric information to evaluate the degree of satisfaction of user-defined digitising accuracy under a triangular topological patch. An industrial case study was used to attest the feasibility of the approach.

Efficacy and Safety of Hair Removal with a Long-Pulsed Diode Laser Depending on the Spot Size: A Randomized, Evaluators-Blinded, Left-Right Study.

PubMed

Jo, Seong Jin; Kim, Jin Yong; Ban, Juhee; Lee, Youngjoo; Kwon, Ohsang; Koh, Wooseok

2015-10-01

The efficacy of the long-pulsed diode laser (LPDL) in hair removal is determined with various physical parameters. Recently, LPDLs with a larger spot size are commercially available; however, the independent effect of spot size on hair removal has not been studied. This study aimed to compare the efficacy of the LPDL in hair removal depending on the spot size. A randomized, evaluators-blind, intrapatient comparison (left vs. right) trial was designed. Ten healthy Korean women received three hair removal treatment sessions on both armpits with the 805-nm LPDL and followed for 3 months. A 10×10 mm handpiece (D1) or a 10×30 mm handpiece (D3) was randomly assigned to the right or left axilla. The fluence, pulse duration, and epidermal cooling temperature were identical for both armpits. Hair clearance was quantified with high-resolution photos taken at each visit. Postprocedural pain was quantified on a visual analogue scale. Adverse events were evaluated by physical examination and the patients' self-report. The mean hair clearance at 3 months after three treatment sessions was 38.7% and 50.1% on the armpits treated with D1 and D3, respectively (p=0.028). Procedural pain was significantly greater in the side treated with D3 (p=0.009). Serious adverse events were not observed. Given that the pulse duration, fluence, and epidermal cooling were identical, the 805-nm LPDL at the three times larger spot size showed an efficacy improvement of 29.5% in axillary hair removal without serious adverse events.

Synergistic effects of dendritic cell targeting and laser-microporation on enhancing epicutaneous skin vaccination efficacy.

PubMed

Machado, Yoan; Duinkerken, Sanne; Hoepflinger, Veronika; Mayr, Melissa; Korotchenko, Evgeniia; Kurtaj, Almedina; Pablos, Isabel; Steiner, Markus; Stoecklinger, Angelika; Lübbers, Joyce; Schmid, Maximillian; Ritter, Uwe; Scheiblhofer, Sandra; Ablinger, Michael; Wally, Verena; Hochmann, Sarah; Raninger, Anna M; Strunk, Dirk; van Kooyk, Yvette; Thalhamer, Josef; Weiss, Richard

2017-11-28

Due to its unique immunological properties, the skin is an attractive target tissue for allergen-specific immunotherapy. In our current work, we combined a dendritic cell targeting approach with epicutaneous immunization using an ablative fractional laser to generate defined micropores in the upper layers of the skin. By coupling the major birch pollen allergen Bet v 1 to mannan from S. cerevisiae via mild periodate oxidation we generated hypoallergenic Bet-mannan neoglycoconjugates, which efficiently targeted CD14 + dendritic cells and Langerhans cells in human skin explants. Mannan conjugation resulted in sustained release from the skin and retention in secondary lymphoid organs, whereas unconjugated antigen showed fast renal clearance. In a mouse model, Bet-mannan neoglycoconjugates applied via laser-microporated skin synergistically elicited potent humoral and cellular immune responses, superior to intradermal injection. The induced antibody responses displayed IgE-blocking capacity, highlighting the therapeutic potential of the approach. Moreover, application via micropores, but not by intradermal injection, resulted in a mixed TH1/TH17-biased immune response. Our data clearly show that applying mannan-neoglycoconjugates to an organ rich in dendritic cells using laser-microporation is superior to intradermal injection. Due to their low IgE binding capacity and biodegradability, mannan neoglycoconjugates therefore represent an attractive formulation for allergen-specific epicutaneous immunotherapy. Copyright © 2017 Elsevier B.V. All rights reserved.

Prognosis and response to laser treatment of early-onset hypertrophic port-wine stains (PWS).

PubMed

Passeron, Thierry; Salhi, Aicha; Mazer, Jean-Michel; Lavogiez, Céline; Mazereeuw-Hautier, Juliette; Galliot, Chrystèle; Collet-Villette, Anne-Marie; Labreze, Christine; Boon, Laurence; Hardy, Jean-Philippe; Fayard, Virginie; Livideanu, Cristina Bulai; Toubel, Gérard; Georgescou, Gabriela; Gral, Nathalie; Maza, Aude; Lacour, Jean-Philippe

2016-07-01

There is limited information regarding early development of soft-tissue and/or bone hypertrophy with facial port-wine stains (PWS). We sought to characterize patients with hypertrophic PWS presenting during childhood. Patients with a facial PWS and underlying hypertrophy that developed before the age of 18 years were included in a multicenter retrospective study. Age at onset of the hypertrophy, its location, association with odontologic problems, presence of other associated complications, and response to laser treatment were recorded. A total of 98 patients were included. The mean age at onset of hypertrophy, retrieved for 77 of 98 patients, was 5.6 years. The hypertrophy was congenital in 26%. Odontologic problems were noted in 39.8% of cases. Other complications, including cataract, asymmetric development of the maxillary bone, and speech delay/disorders, were reported in 18.4%. In all, 67 patients received laser treatment. Only 3% achieved complete or nearly complete clearance of the PWS. As only cases of PWS with early-onset hypertrophy were included, we were unable to calculate the prevalence of this manifestation. PWS with early-onset hypertrophy are associated with a high rate of complications and a poor response to laser treatment. Periodic monitoring is recommended for early detection and treatment of complications. Copyright © 2016 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.

Automatic determination of trunk diameter, crown base and height of scots pine (Pinus Sylvestris L.) Based on analysis of 3D point clouds gathered from multi-station terrestrial laser scanning. (Polish Title: Automatyczne okreslanie srednicy pnia, podstawy korony oraz wysokosci sosny zwyczajnej (Pinus Silvestris L.) Na podstawie analiz chmur punktow 3D pochodzacych z wielostanowiskowego naziemnego skanowania laserowego)

NASA Astrophysics Data System (ADS)

Ratajczak, M.; Wężyk, P.

2015-12-01

Rapid development of terrestrial laser scanning (TLS) in recent years resulted in its recognition and implementation in many industries, including forestry and nature conservation. The use of the 3D TLS point clouds in the process of inventory of trees and stands, as well as in the determination of their biometric features (trunk diameter, tree height, crown base, number of trunk shapes), trees and lumber size (volume of trees) is slowly becoming a practice. In addition to the measurement precision, the primary added value of TLS is the ability to automate the processing of the clouds of points 3D in the direction of the extraction of selected features of trees and stands. The paper presents the original software (GNOM) for the automatic measurement of selected features of trees, based on the cloud of points obtained by the ground laser scanner FARO. With the developed algorithms (GNOM), the location of tree trunks on the circular research surface was specified and the measurement was performed; the measurement covered the DBH (l: 1.3m), further diameters of tree trunks at different heights of the tree trunk, base of the tree crown and volume of the tree trunk (the selection measurement method), as well as the tree crown. Research works were performed in the territory of the Niepolomice Forest in an unmixed pine stand (Pinussylvestris L.) on the circular surface with a radius of 18 m, within which there were 16 pine trees (14 of them were cut down). It was characterized by a two-storey and even-aged construction (147 years old) and was devoid of undergrowth. Ground scanning was performed just before harvesting. The DBH of 16 pine trees was specified in a fully automatic way, using the algorithm GNOM with an accuracy of +2.1%, as compared to the reference measurement by the DBH measurement device. The medium, absolute measurement error in the cloud of points - using semi-automatic methods "PIXEL" (between points) and PIPE (fitting the cylinder) in the FARO Scene 5.x., showed the error, 3.5% and 5.0%,.respectively The reference height was assumed as the measurement performed by the tape on the cut tree. The average error of automatic determination of the tree height by the algorithm GNOM based on the TLS point clouds amounted to 6.3% and was slightly higher than when using the manual method of measurements on profiles in the TerraScan (Terrasolid; the error of 5.6%). The relatively high value of the error may be mainly related to the small number of points TLS in the upper parts of crowns. The crown height measurement showed the error of +9.5%. The reference in this case was the tape measurement performed already on the trunks of cut pine trees. Processing the clouds of points by the algorithms GNOM for 16 analyzed trees took no longer than 10 min. (37 sec. /tree). The paper mainly showed the TLS measurement innovation and its high precision in acquiring biometric data in forestry, and at the same time also the further need to increase the degree of automation of processing the clouds of points 3D from terrestrial laser scanning.

Efficacy and safety of Ho:YAG Laser Lithotripsy for ureteroscopic removal of proximal and distal ureteral calculi

PubMed Central

2014-01-01

Background Laser lithotripsy is an established endourological modality. Ho:YAG laser have broadened the indications for ureteroscopic stone managements to include larger stone sizes throughout the whole upper urinary tract. Aim of current work is to assess efficacy and safety of Ho:YAG laser lithotripsy during retrograde ureteroscopic management of ureteral calculi in different locations. Methods 88 patients were treated with ureteroscopic Ho:YAG laser lithotripsy in our institute. Study endpoint was the number of treatments until the patient was stone-free. Patients were classified according to the location of their stones as Group I (distal ureteric stones, 51 patients) and group II (proximal ureteral stones, 37). Group I patients have larger stones as Group II (10.70 mm vs. 8.24 mm, respectively, P = 0.020). Results Overall stone free rate for both groups was 95.8%. The mean number of procedures for proximal calculi was 1.1 ± 0.1 (1–3) and for distal calculi was 1.0 ± 0.0. The initial treatment was more successful in patients with distal ureteral calculi (100% vs. 82.40%, respectively, P = 0.008). No significant difference in the stone free rate was noticed after the second laser procedure for stones smaller versus larger than 10 mm (100% versus 94.1%, P = 0.13). Overall complication rate was 7.9% (Clavien II und IIIb). Overall and grade-adjusted complication rates were not dependant on the stone location. No laser induced complications were noticed. Conclusions The use of the Ho:YAG laser appears to be an adequate tool to disintegrate ureteral calculi independent of primary location. Combination of the semirigid and flexible ureteroscopes as well as the appropriate endourologic tools could likely improve the stone clearance rates for proximal calculi regardless of stone-size. PMID:25107528

The Fringe Reading Facility at the Max-Planck-Institut fuer Stroemungsforschung

NASA Astrophysics Data System (ADS)

Becker, F.; Meier, G. E. A.; Wegner, H.; Timm, R.; Wenskus, R.

1987-05-01

A Mach-Zehnder interferometer is used for optical flow measurements in a transonic wind tunnel. Holographic interferograms are reconstructed by illumination with a He-Ne-laser and viewed by a video camera through wide angle optics. This setup was used for investigating industrial double exposure holograms of truck tires in order to develop methods of automatic recognition of certain manufacturing faults. Automatic input is achieved by a transient recorder digitizing the output of a TV camera and transferring the digitized data to a PDP11-34. Interest centered around sequences of interferograms showing the interaction of vortices with a profile and subsequent emission of sound generated by this process. The objective is the extraction of quantitative data which relates to the emission of noise.

The Fringe Reading Facility at the Max-Planck-Institut fuer Stroemungsforschung

NASA Technical Reports Server (NTRS)

Becker, F.; Meier, G. E. A.; Wegner, H.; Timm, R.; Wenskus, R.

1987-01-01

A Mach-Zehnder interferometer is used for optical flow measurements in a transonic wind tunnel. Holographic interferograms are reconstructed by illumination with a He-Ne-laser and viewed by a video camera through wide angle optics. This setup was used for investigating industrial double exposure holograms of truck tires in order to develop methods of automatic recognition of certain manufacturing faults. Automatic input is achieved by a transient recorder digitizing the output of a TV camera and transferring the digitized data to a PDP11-34. Interest centered around sequences of interferograms showing the interaction of vortices with a profile and subsequent emission of sound generated by this process. The objective is the extraction of quantitative data which relates to the emission of noise.

Differential GPS/inertial navigation approach/landing flight test results

NASA Technical Reports Server (NTRS)

Snyder, Scott; Schipper, Brian; Vallot, Larry; Parker, Nigel; Spitzer, Cary

1992-01-01

In November of 1990 a joint Honeywell/NASA-Langley differential GPS/inertial flight test was conducted at Wallops Island, Virginia. The test objective was to acquire a system performance database and demonstrate automatic landing using an integrated differential GPS/INS (Global Positioning System/inertial navigation system) with barometric and radar altimeters. The flight test effort exceeded program objectives with over 120 landings, 36 of which were fully automatic differential GPS/inertial landings. Flight test results obtained from post-flight data analysis are discussed. These results include characteristics of differential GPS/inertial error, using the Wallops Island Laser Tracker as a reference. Data on the magnitude of the differential corrections and vertical channel performance with and without radar altimeter augmentation are provided.

High efficient bone ablation with diode pumped Erbium and Thulium lasers including different delivery fibers: a comparative in vitro study

NASA Astrophysics Data System (ADS)

Stock, Karl; Hausladen, Florian; Stegmayer, Thomas; Wurm, Holger

2018-02-01

Er:YAG lasers (3μm) allow efficient bone ablation caused by the strong absorption in water. Unfortunately, there are only a few and comparable expensive fiber materials for this wavelength available which are suitable for high laser power. The bone ablation efficiency of the Tm:YAG laser is minor (2μm) but inexpensive silica fibers can be used. The aim of this study was to investigate the bone ablation, using novel diode pumped high power Er:YAG (laser power 40W) and Tm:YAG laser system (60W) and adaptive fiber delivery systems. Expected advantage of these lasers is the longer lifetime of the fibers because of the high repetition rate and low pulse energy compared to the flash lamp pumped laser systems. The bare fiber output ends of a sapphire fiber (Er:YAG laser) and of a silica fiber (Tm:YAG laser) were attached under water and a water filled container including the fixed sample (bovine bone slices) was moved by a computer controlled translation stage. In a second set-up we provided a focusing unit and appropriate water spray unit. The generated cut kerfs were analyzed by light microcopy and laser scanning microscopy. The results show that with the diode pumped Er:YAG laser and sapphire fiber a particular high efficient bone ablation (> 0.16mm2/J) is possible both with bare fiber under water and focusing unit with water spray. The higher power of the Tm:YAG laser also results in high ablation rates but causes enlarged thermal damages. In conclusion, this study demonstrates that efficient bone ablation is possible with both diode pumped laser systems. In terms of efficiency the Er:YAG laser is outstanding. The Tm:YAG laser also allows fast bone ablation, provided that the thermal impact is limited by effective cooling and high movement velocity of the laser spot, for example by using an automatic scanner.

Study of working principle and thermal balance process of a double longitudinal-mode He-Ne laser

NASA Astrophysics Data System (ADS)

Wang, Li-qiang

2009-07-01

A double longitudinal mode He-Ne laser with frequency stabilization is proposed. Compared with general methods, such as Lamb dip, Zeeman splitting and molecule saturation absorption method, this design has some advantages, such as no piezocrystal or magnetic field, a short frequency-stabilized time, lower cost, and higher frequency stability and reproducibility. The metal wire is uniformly wrapped on the discharge tube of the laser. When the metal wire is heated up, the resonant cavity changes with the temperature field around the discharge tube to make the frequency of the laser to be tuned. The polarizations of the two longitudinal modes from the laser must be orthogonal. The parallelly polarized light and the vertically polarized light compete with each other, i. e., the parallelly polarized light generates a larger output power, while, the vertically polarized light correspondingly generates a smaller one, but an equal value is found at the reference frequencies by automatically adjusting the length of the resonant cavity, due to change of the temperature in the discharge tube. Consequently the frequencies of the laser are stabilized. In my experiment, an intracavity He-Ne laser whose length of the resonant cavity is larger than 50mm and smaller than 300mm is selected for the double longitudinal-mode laser. Influence factors of frequency stability of this laser is only change of the length of the resonant cavity. The laser includes three stages: mode hopping, transition stage, and modes stability from startup to laser stability. When this laser is in modes stability, the waveform of heating metal wire is observed to a pulse whose duty is almost 50%, and thermal balances of the resonant cavity mainly rely on discharge tube.

Pulsed dye laser double-pass treatment of patients with resistant capillary malformations.

PubMed

Rajaratnam, Ratna; Laughlin, Sharyn A; Dudley, Denis

2011-07-01

The pulsed dye laser is an effective and established treatment for port-wine stains and has become the generally accepted standard of care. However, in many cases, complete clearance cannot be achieved as a significant proportion of lesions become resistant to treatment. Multiple passes or pulse-stacking techniques have been used to improve the extent and rate of fading, but concerns over increased adverse effects have limited this clinical approach. In this work, a double-pass technique with the pulsed dye laser has been described, which may allow for increased depth of vascular injury, greater efficacy, and an acceptable risk profile. Our aim was to determine the efficacy and the rate of side-effects for a double-pass protocol with a pulsed dye laser (PDL) to treat patients previously treated with PDL and/or other laser modalities. A retrospective chart review was conducted of 26 patients treated with a minimum of three double-pass treatments alone, or in combination, with single pass conventional PDL. Almost half of the patients (n = 12) showed either a moderate or significant improvement in fading compared to pre-treatment photographs with the double-pass technique. In a further 12 patients, there was a mild improvement. In two patients, there was no change. Sixteen patients developed mild side-effects: blisters (n = 5), dry scabs (n = 11) and transient hyperpigmentation (n = 4). This preliminary experience suggests that a double-pass technique at defined intervals between the first and second treatment with PDL can further lighten some port-wine stains, which are resistant to conventional single-pass treatments. This technique may be a useful addition to the laser treatment of PWS and deserves further scrutiny with randomized prospective studies and histological analysis to confirm the increased depth of vascular injury.

High speed pulsed laser cutting of LiCoO2 Li-ion battery electrodes

NASA Astrophysics Data System (ADS)

Lutey, Adrian H. A.; Fortunato, Alessandro; Carmignato, Simone; Fiorini, Maurizio

2017-09-01

Laser cutting of Li-ion battery electrodes represents an alternative to mechanical blanking that avoids complications associated with tool wear and allows assembly of different cell geometries with a single device. In this study, laser cutting of LiCoO2 Li-ion battery electrodes is performed at up to 5m /s with a 1064nm wavelength nanosecond pulsed fiber laser with a maximum average power of 500W and a repetition rate of up to 2MHz . Minimum average cutting power for cathode and anode multi-layer films is established for 12 parameter groups with velocities over the range 1 - 5m /s , varying laser pulse fluence and overlap. Within the tested parameter range, minimum energy per unit cut length is found to decrease with increasing repetition rate and velocity. SEM analysis of the resulting cut edges reveals visible clearance widths in the range 20 - 50 μm , with cut quality found to improve with velocity due to a reduction in lateral heat conduction losses. Raman line map spectra reveal changes in the cathode at 60 μm from the cut edge, where bands at 486cm-1 and 595cm-1 , corresponding to the Eg and A1g modes of LiCoO2 , are replaced with a single wide band centered at 544cm-1 , and evidence of carbon black is no longer present. No changes in Raman spectra are observed in the anode. The obtained results suggest that further improvements in cutting efficiency and quality could be achieved by increasing the repetition rate above 2MHz , thereby improving ablation efficiency of the metallic conductor layers. The laser source utilized in the present study nonetheless represents an immediately available solution for repeatability and throughput that are superior to mechanical blanking.

Retrospective single center study of the efficacy of large spot 532 nm laser for the treatment of facial capillary malformations in 44 patients with the use of three-dimensional image analysis.

PubMed

Kwiek, Bartłomiej; Rożalski, Michał; Kowalewski, Cezary; Ambroziak, Marcin

2017-10-01

We wanted to asses the efficacy of large spot 532 nm laser for the treatment of facial capillary malformations with the use of three-dimensional (3D) image analysis. Retrospective single center study on previously non-treated patients with facial capillary malformations (CM) was performed. A total of 44 consecutive Caucasian patients aged 5-66 were included. Patients had 3D photography performed before and after and had at least one single session of treatment with 532 nm neodymium-doped yttrium aluminum garnet (Nd:YAG) laser with contact cooling, fluencies ranging from 8 to 11.5 J/cm 2 , pulse duration ranging from 5 to 9 milliseconds and spot size ranging from 5 to 10 mm. Objective analysis of percentage improvement based on 3D digital assessment of combined color and area improvement (global clearance effect [GCE]) were performed. Median maximal improvement achieved during the treatment (GCE max ) was 70.4%. Mean number of laser procedures required to achieve this improvement was 7.1 (ranging from 2 to 14)). Improvement of minimum 25% (GCE 25) was achieved by all patients, of minimum 50% (GCE 50) by 77.3%, of minimum 75% (GCE 75) by 38.6%, and of minimum 90% (GCE 90) by 13.64. Large spot 532 nm laser is highly effective in the treatment of facial CM. 3D color and area image analysis provides an objective method to compare different methods of facial CM treatment in future studies. Lasers Surg. Med. 49:743-749, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Laser-aided material identification for the waste sorting process

NASA Astrophysics Data System (ADS)

Haferkamp, Heinz; Burmester, Ingo; Engel, Kai

1994-03-01

The LZH has carried out investigations in the field of rapid laser-supported material- identification systems for automatic material-sorting systems. The aim of this research is the fast identification of different sorts of plastics coming from recycled rubbish or electronic waste. Within a few milliseconds a spot on the sample which has to be identified is heated with a CO2 laser. The different and specific chemical and physical material properties of the examined sample cause a different temperature distribution on the surface which is measured with an IR thermographic system. This `thermal impulse response' has to be analyzed by means of a computer system. The results of previous investigations have shown that material identification of different sorts of plastics can possibly be done at a frequency of 30 Hz. Due to economic efficiency, a high velocity identification process is necessary to sort huge waste currents.

Self-starting, self-regulating Fourier domain mode locked fiber laser for OCT imaging

PubMed Central

Murari, Kartikeya; Mavadia, Jessica; Xi, Jiefeng; Li, Xingde

2011-01-01

We present a Fourier domain mode locking (FDML) fiber laser with a feedback loop allowing automatic startup without a priori knowledge of the fundamental drive frequency. The feedback can also regulate the drive frequency making the source robust against environmental variations. A control system samples the energy of the light traversing the FDML cavity and uses a voltage controlled oscillator (VCO) to drive the tunable fiber Fabry-Perot filter in order to maximize that energy. We demonstrate a prototype self-starting, self-regulating FDML operating at 40 kHz with a full width tuning range of 140 nm around 1305 nm and a power output of ~40 mW. The laser starts up with no operator intervention in less than 5 seconds and exhibits improved spectral stability over a conventional FDML source. In OCT applications the source achieved over 120 dB detection sensitivity and an ~8.9-µm axial resolution. PMID:21750775

Fast, precise, and widely tunable frequency control of an optical parametric oscillator referenced to a frequency comb.

PubMed

Prehn, Alexander; Glöckner, Rosa; Rempe, Gerhard; Zeppenfeld, Martin

2017-03-01

Optical frequency combs (OFCs) provide a convenient reference for the frequency stabilization of continuous-wave lasers. We demonstrate a frequency control method relying on tracking over a wide range and stabilizing the beat note between the laser and the OFC. The approach combines fast frequency ramps on a millisecond timescale in the entire mode-hop free tuning range of the laser and precise stabilization to single frequencies. We apply it to a commercially available optical parametric oscillator (OPO) and demonstrate tuning over more than 60 GHz with a ramping speed up to 3 GHz/ms. Frequency ramps spanning 15 GHz are performed in less than 10 ms, with the OPO instantly relocked to the OFC after the ramp at any desired frequency. The developed control hardware and software are able to stabilize the OPO to sub-MHz precision and to perform sequences of fast frequency ramps automatically.

Investigation of Cutting Quality of Remote DOE Laser Cutting in 0.5 mm Stainless Steel

NASA Astrophysics Data System (ADS)

Villumsen, Sigurd Lazic; Kristiansen, Morten

It has previously been shown that the stability of the remote fusion cutting (RFC) process can be increased by modifying the intensity profile of the laser by means of a diffractive optical element (DOE). This paper investigates the quality of remote DOE cutting (RDC) conducted with a 3 kW single mode fiber laser in 0.5 mm stainless steel. An automatic measurement system is used to investigate how the travel speed, focus offset and angle of incidence effect the kerf width and kerf variance. The study shows that the RDC process has a very low kerf width variance, and that the kerf width decreases with cutting speed. Furthermore, selected etched samples show a significant increase in the perpendicularity of the cuts when compared to RFC. Also, on average, the depth of the layer of molten material for RFC is 83% deeper than for RDC.

Laser Scanner For Automatic Storage

NASA Astrophysics Data System (ADS)

Carvalho, Fernando D.; Correia, Bento A.; Rebordao, Jose M.; Rodrigues, F. Carvalho

1989-01-01

The automated magazines are beeing used at industry more and more. One of the problems related with the automation of a Store House is the identification of the products envolved. Already used for stock management, the Bar Codes allows an easy way to identify one product. Applied to automated magazines, the bar codes allows a great variety of items in a small code. In order to be used by the national producers of automated magazines, a devoted laser scanner has been develloped. The Prototype uses an He-Ne laser whose beam scans a field angle of 75 degrees at 16 Hz. The scene reflectivity is transduced by a photodiode into an electrical signal, which is then binarized. This digital signal is the input of the decodifying program. The machine is able to see barcodes and to decode the information. A parallel interface allows the comunication with the central unit, which is responsible for the management of automated magazine.

Fast and automatic depth control of iterative bone ablation based on optical coherence tomography data

NASA Astrophysics Data System (ADS)

Fuchs, Alexander; Pengel, Steffen; Bergmeier, Jan; Kahrs, Lüder A.; Ortmaier, Tobias

2015-07-01

Laser surgery is an established clinical procedure in dental applications, soft tissue ablation, and ophthalmology. The presented experimental set-up for closed-loop control of laser bone ablation addresses a feedback system and enables safe ablation towards anatomical structures that usually would have high risk of damage. This study is based on combined working volumes of optical coherence tomography (OCT) and Er:YAG cutting laser. High level of automation in fast image data processing and tissue treatment enables reproducible results and shortens the time in the operating room. For registration of the two coordinate systems a cross-like incision is ablated with the Er:YAG laser and segmented with OCT in three distances. The resulting Er:YAG coordinate system is reconstructed. A parameter list defines multiple sets of laser parameters including discrete and specific ablation rates as ablation model. The control algorithm uses this model to plan corrective laser paths for each set of laser parameters and dynamically adapts the distance of the laser focus. With this iterative control cycle consisting of image processing, path planning, ablation, and moistening of tissue the target geometry and desired depth are approximated until no further corrective laser paths can be set. The achieved depth stays within the tolerances of the parameter set with the smallest ablation rate. Specimen trials with fresh porcine bone have been conducted to prove the functionality of the developed concept. Flat bottom surfaces and sharp edges of the outline without visual signs of thermal damage verify the feasibility of automated, OCT controlled laser bone ablation with minimal process time.

Encapsulation of indocyanine green into cell membrane capsules for photothermal cancer therapy.

PubMed

Sheng, Guoping; Chen, Ying; Han, Lijie; Huang, Yong; Liu, Xiaoli; Li, Lanjuan; Mao, Zhengwei

2016-10-01

Although indocyanine green (ICG) has promising applications in photothermal therapy (PPT) because of its low toxicity and high efficiency in inducing heat and singlet oxygen formation in response to near-infrared light with a wavelength of approximately 800nm, its clinical application has been restricted because of its rapid body clearance and poor water stability. Therefore, cell membrane capsules (CMCs) derived from mammalian cells were used to encapsulate negatively charged ICG by temporarily permeating the plasma membrane and resealing using positively charged doxorubicin hydrochloride (DOX). The resulting CMCs@DOX/ICG exhibited a spherical shape, with a diameter of approximately 800nm. The DOX and ICG encapsulation was confirmed by the UV-vis spectrum; a very small amount of DOX (0.8μg) and a very high amount of ICG (∼110μg) were encapsulated in 200μg CMCs. Encapsulation in the CMCs leads to sustained release of ICG, especially in the presence of positively charged DOX. The temperature enhancement and generation of ROS by ICG encapsulated in CMCs were confirmed upon laser irradiation in vitro, leading to cell death. CMCs@DOX/ICG also can significantly enhance the retention of ICG in a tumor after intratumoral injection in vivo. As a result, combination treatment with CMCs@DOX/ICG and laser irradiation demonstrated much better anticancer efficacy than that of free DOX/ICG and CMCs@ICG. The encapsulation of ICG into CMCs, especially with the assistance of DOX, significantly slows down the body clearance of ICG, with a retained PPT effect against tumors, an important step forward in the practical application of ICG in cancer therapy. In this study, cell membrane capsules (CMCs) derived from mammalian cells were used to encapsulate negatively charged indocyanine green (ICG) by temporarily permeating the plasma membrane and resealing, in the presence of positively charged doxorubicin hydrochloride (DOX). The resulting CMCs@DOX/ICG exhibited a spherical shape, with a diameter of approximately 800nm. Encapsulation in the CMCs leads to sustained release of ICG and thus slower clearance inside body, especially in the presence of positively charged DOX. The system provides a better photothermal effect against tumors, an important step forward in the practical application of ICG in cancer therapy. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Using airborne LiDAR in geoarchaeological contexts: Assessment of an automatic tool for the detection and the morphometric analysis of grazing archaeological structures (French Massif Central).

NASA Astrophysics Data System (ADS)

Roussel, Erwan; Toumazet, Jean-Pierre; Florez, Marta; Vautier, Franck; Dousteyssier, Bertrand

2014-05-01

Airborne laser scanning (ALS) of archaeological regions of interest is nowadays a widely used and established method for accurate topographic and microtopographic survey. The penetration of the vegetation cover by the laser beam allows the reconstruction of reliable digital terrain models (DTM) of forested areas where traditional prospection methods are inefficient, time-consuming and non-exhaustive. The ALS technology provides the opportunity to discover new archaeological features hidden by vegetation and provides a comprehensive survey of cultural heritage sites within their environmental context. However, the post-processing of LiDAR points clouds produces a huge quantity of data in which relevant archaeological features are not easily detectable with common visualizing and analysing tools. Undoubtedly, there is an urgent need for automation of structures detection and morphometric extraction techniques, especially for the "archaeological desert" in densely forested areas. This presentation deals with the development of automatic detection procedures applied to archaeological structures located in the French Massif Central, in the western forested part of the Puy-de-Dôme volcano between 950 and 1100 m a.s.l.. These unknown archaeological sites were discovered by the March 2011 ALS mission and display a high density of subcircular depressions with a corridor access. The spatial organization of these depressions vary from isolated to aggregated or aligned features. Functionally, they appear to be former grazing constructions built from the medieval to the modern period. Similar grazing structures are known in other locations of the French Massif Central (Sancy, Artense, Cézallier) where the ground is vegetation-free. In order to develop a reliable process of automatic detection and mapping of these archaeological structures, a learning zone has been delineated within the ALS surveyed area. The grazing features were mapped and typical morphometric attributes were calculated based on 2 methods: (i) The mapping of the archaeological structures by a human operator using common visualisation tools (DTM, multi-direction hillshading & local relief models) within a GIS environment; (ii) The automatic detection and mapping performed by a recognition algorithm based on a user defined geometric pattern of the grazing structures. The efficiency of the automatic tool has been assessed by comparing the number of structures detected and the morphometric attributes calculated by the two methods. Our results indicate that the algorithm is efficient for the detection and the location of grazing structures. Concerning the morphometric results, there is still a discrepancy between automatic and expert calculations, due to both the expert mapping choices and the algorithm calibration.

Refractive index change mechanisms in different glasses induced by femtosecond laser irradiation

NASA Astrophysics Data System (ADS)

Fuerbach, A.; Gross, S.; Little, D.; Arriola, A.; Ams, M.; Dekker, P.; Withford, M.

2016-07-01

Tightly focused femtosecond laser pulses can be used to alter the refractive index of virtually all optical glasses. As the laser-induced modification is spatially limited to the focal volume of the writing beam, this technique enables the fabrication of fully three-dimensional photonic structures and devices that are automatically embedded within the host material. While it is well understood that the laser-material interaction process is initiated by nonlinear, typically multiphoton absorption, the actual mechanism that results in an increase or sometimes decrease of the refractive index of the glass strongly depends on the composition of the material and the process parameters and is still subject to scientific studies. In this paper, we present an overview of our recent work aimed at uncovering the physical and chemical processes that contribute to the observed material modification. Raman microscopy and electron microprobe analysis was used to study the induced modifications that occur within the glass matrix and the influence of atomic species migration forced by the femtosecond laser writing beam. In particular, we concentrate on borosilicate, heavy metal fluoride and phosphate glasses. We believe that our results represent an important step towards the development of engineered glass types that are ideally suited for the fabrication of photonic devices via the femtosecond laser direct write technique.

Optical Coherence Tomography Guided Laser Cochleostomy: Towards the Accuracy on Tens of Micrometer Scale

PubMed Central

Weller, Marcel; Wieser, Wolfgang; Huber, Robert; Raczkowsky, Jörg; Schipper, Jörg; Wörn, Heinz; Klenzner, Thomas

2014-01-01

Lasers have been proven to be precise tools for bone ablation. Applying no mechanical stress to the patient, they are potentially very suitable for microsurgery on fragile structures such as the inner ear. However, it remains challenging to control the laser-bone ablation without injuring embedded soft tissue. In this work, we demonstrate a closed-loop control of a short-pulsed CO2 laser to perform laser cochleostomy under the monitoring of an optical coherence tomography (OCT) system. A foresighted detection of the bone-endosteum-perilymph boundary several hundred micrometers before its exposure has been realized. Position and duration of the laser pulses are planned based on the residual bone thickness distribution. OCT itself is also used as a highly accurate tracking system for motion compensation between the target area and the optics. During ex vivo experimental evaluation on fresh porcine cochleae, the ablation process terminated automatically when the thickness of the residual tissue layer uniformly reached a predefined value. The shape of the resulting channel bottom converged to the natural curvature of the endosteal layer without injuring the critical structure. Preliminary measurements in OCT scans indicated that the mean absolute accuracy of the shape approximation was only around 20 μm. PMID:25295253

Arduino Due based tool to facilitate in vivo two-photon excitation microscopy

PubMed Central

Artoni, Pietro; Landi, Silvia; Sato, Sebastian Sulis; Luin, Stefano; Ratto, Gian Michele

2016-01-01

Two-photon excitation spectroscopy is a powerful technique for the characterization of the optical properties of genetically encoded and synthetic fluorescent molecules. Excitation spectroscopy requires tuning the wavelength of the Ti:sapphire laser while carefully monitoring the delivered power. To assist laser tuning and the control of delivered power, we developed an Arduino Due based tool for the automatic acquisition of high quality spectra. This tool is portable, fast, affordable and precise. It allowed studying the impact of scattering and of blood absorption on two-photon excitation light. In this way, we determined the wavelength-dependent deformation of excitation spectra occurring in deep tissues in vivo. PMID:27446677

NIF Ignition Target 3D Point Design

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, O; Marinak, M; Milovich, J

2008-11-05

We have developed an input file for running 3D NIF hohlraums that is optimized such that it can be run in 1-2 days on parallel computers. We have incorporated increasing levels of automation into the 3D input file: (1) Configuration controlled input files; (2) Common file for 2D and 3D, different types of capsules (symcap, etc.); and (3) Can obtain target dimensions, laser pulse, and diagnostics settings automatically from NIF Campaign Management Tool. Using 3D Hydra calculations to investigate different problems: (1) Intrinsic 3D asymmetry; (2) Tolerance to nonideal 3D effects (e.g. laser power balance, pointing errors); and (3) Syntheticmore » diagnostics.« less

Characterization of silicon micro-strip sensors with a pulsed infra-red laser system for the CBM experiment at FAIR

NASA Astrophysics Data System (ADS)

Ghosh, P.

2015-03-01

The Compressed Baryonic Matter (CBM) experiment at FAIR is composed of 8 tracking stations consisting of 1292 double sided silicon micro-strip sensors. For the quality assurance of produced prototype sensors a laser test system (LTS) has been developed. The aim of the LTS is to scan sensors with a pulsed infra-red laser driven by step motor to determine the charge sharing in-between strips and to measure qualitative uniformity of the sensor response over the whole active area. The prototype sensors which are tested with the LTS so far have 256 strips with a pitch of 50 μm on each side. They are read-out using a self-triggering prototype read-out electronic ASIC called n-XYTER. The LTS is designed to measure sensor response in an automatized procedure at several thousand positions across the sensor with focused infra-red laser light (spot size ≈ 12 μm , wavelength = 1060 nm). The pulse with duration (≈ 10 ns) and power (≈ 5 mW) of the laser pulses is selected such, that the absorption of the laser light in the 300 μm thick silicon sensors produces a number of about 24000 electrons, which is similar to the charge created by minimum ionizing particles (MIP) in these sensors. Laser scans different prototype sensors is reported.

Functional enucleation of porcine oocytes for somatic cell nuclear transfer using femtosecond laser pulses

NASA Astrophysics Data System (ADS)

Kuetemeyer, K.; Lucas-Hahn, A.; Petersen, B.; Hassel, P.; Lemme, E.; Niemann, H.; Heisterkamp, A.

2010-02-01

Cloning of several mammalian species has been achieved by somatic cell nuclear transfer over the last decade. However, this method still results in very low efficiencies originating from biological and technical aspects. The highly-invasive mechanical enucleation belongs to the technical aspects and requires considerable micromanipulation skill. In this paper, we present a novel non-invasive method for combined oocyte imaging and automated functional enucleation using femtosecond (fs) laser pulses. After three-dimensional imaging of Hoechst-labeled porcine oocytes by multiphoton microscopy, our self-developed software automatically determined the metaphase plate position and shape. Subsequent irradiation of this volume with the very same laser at higher pulse energies in the low-density-plasma regime was used for metaphase plate ablation. We show that functional fs laser-based enucleation of porcine oocytes completely inhibited further embryonic development while maintaining intact oocyte morphology. In contrast, non-irradiated oocytes were able to develop to the blastocyst stage without significant differences to control oocytes. Our results indicate that fs laser systems offer great potential for oocyte imaging and enucleation as a fast, easy to use and reliable tool which may improve the efficiency of somatic cell clone production.

Progress toward a practical laser driven ion source using variable thickness liquid crystal targets

NASA Astrophysics Data System (ADS)

Poole, Patrick; Cochran, Ginevra; Zeil, Karl; Metzkes, Josephine; Obst, Lieselotte; Kluge, Thomas; Schlenvoigt, Hans-Peter; Prencipe, Irene; Cowan, Tom; Schramm, Uli; Schumacher, Douglass

2016-10-01

Ion acceleration from ultra-intense laser interaction has been long investigated in pursuit of requisite energies and spectral distributions for applications like proton cancer therapy. However, the details of ion acceleration mechanisms and their laser intensity scaling are not fully understood, especially the complete role of pulse contrast and target thickness. Additionally, target delivery and alignment at appropriate rates for study and subsequent treatment pose significant challenges. We present results from a campaign on the Draco laser using liquid crystal targets that have on-demand, in-situ thickness tunability over more than three orders of magnitude, enabling rapid data collection due to <1 minute, automatically aligned target formation. Diagnostics include spectral and spatial measurement of ions, electrons, and reflected and transmitted light, all with thickness, laser focus, and pulse contrast variations. In particular we discuss optimal thickness vs. contrast and details of ultra-thin target normal ion acceleration, along with supporting particle-in-cell studies. This work was supported by the DARPA PULSE program through AMRDEC, by the NNSA (DE-NA0001976), by EC Horizon 2020 LASERLAB-EUROPE/LEPP (654148), and by the German Federal Ministry of Education and Research (BMBF, 03Z1O511).

Integrated calibration between digital camera and laser scanner from mobile mapping system for land vehicles

NASA Astrophysics Data System (ADS)

Zhao, Guihua; Chen, Hong; Li, Xingquan; Zou, Xiaoliang

The paper presents the concept of lever arm and boresight angle, the design requirements of calibration sites and the integrated calibration method of boresight angles of digital camera or laser scanner. Taking test data collected by Applanix's LandMark system as an example, the camera calibration method is introduced to be piling three consecutive stereo images and OTF-Calibration method using ground control points. The laser calibration of boresight angle is proposed to use a manual and automatic method with ground control points. Integrated calibration between digital camera and laser scanner is introduced to improve the systemic precision of two sensors. By analyzing the measurement value between ground control points and its corresponding image points in sequence images, a conclusion is that position objects between camera and images are within about 15cm in relative errors and 20cm in absolute errors. By comparing the difference value between ground control points and its corresponding laser point clouds, the errors is less than 20cm. From achieved results of these experiments in analysis, mobile mapping system is efficient and reliable system for generating high-accuracy and high-density road spatial data more rapidly.

Investigation of Laser Induced Breakdown Spectroscopy (LIBS) for the Differentiation of Nerve and Gland Tissue—A Possible Application for a Laser Surgery Feedback Control Mechanism

NASA Astrophysics Data System (ADS)

Mehari, F.; Rohde, M.; Knipfer, C.; Kanawade, R.; Klämpfl, F.; W., Adler; Oetter, N.; Stelzle, F.; Schmidt, M.

2016-06-01

Laser surgery provides clean, fast and accurate modeling of tissue. However, the inability to determine what kind of tissue is being ablated at the bottom of the cut may lead to the iatrogenic damage of structures that were meant to be preserved. In this context, nerve preservation is one of the key challenges in any surgical procedure. One example is the treatment of parotid gland pathologies, where the facial nerve (N. VII) and its main branches run through and fan out inside the glands parenchyma. A feedback system that automatically stops the ablation to prevent nerve-tissue damage could greatly increase the applicability and safety of surgical laser systems. In the present study, Laser Induced Breakdown Spectroscopy (LIBS) is used to differentiate between nerve and gland tissue of an ex-vivo pig animal model. The LIBS results obtained in this preliminary experiment suggest that the measured spectra, containing atomic and molecular emissions, can be used to differentiate between the two tissue types. The measurements and differentiation were performed in open air and under normal stray light conditions.

D Model of AL Zubarah Fortress in Qatar - Terrestrial Laser Scanning VS. Dense Image Matching

NASA Astrophysics Data System (ADS)

Kersten, T.; Mechelke, K.; Maziull, L.

2015-02-01

In September 2011 the fortress Al Zubarah, built in 1938 as a typical Arabic fortress and restored in 1987 as a museum, was recorded by the HafenCity University Hamburg using terrestrial laser scanning with the IMAGER 5006h and digital photogrammetry for the Qatar Museum Authority within the framework of the Qatar Islamic Archaeology and Heritage Project. One goal of the object recording was to provide detailed 2D/3D documentation of the fortress. This was used to complete specific detailed restoration work in the recent years. From the registered laser scanning point clouds several cuttings and 2D plans were generated as well as a 3D surface model by triangle meshing. Additionally, point clouds and surface models were automatically generated from digital imagery from a Nikon D70 using the open-source software Bundler/PMVS2, free software VisualSFM, Autodesk Web Service 123D Catch beta, and low-cost software Agisoft PhotoScan. These outputs were compared with the results from terrestrial laser scanning. The point clouds and surface models derived from imagery could not achieve the same quality of geometrical accuracy as laser scanning (i.e. 1-2 cm).

Cells and Stripes: A novel quantitative photo-manipulation technique

PubMed Central

Mistrik, Martin; Vesela, Eva; Furst, Tomas; Hanzlikova, Hana; Frydrych, Ivo; Gursky, Jan; Majera, Dusana; Bartek, Jiri

2016-01-01

Laser micro-irradiation is a technology widely used in the DNA damage response, checkpoint signaling, chromatin remodeling and related research fields, to assess chromatin modifications and recruitment of diverse DNA damage sensors, mediators and repair proteins to sites of DNA lesions. While this approach has aided numerous discoveries related to cell biology, maintenance of genome integrity, aging and cancer, it has so far been limited by a tedious manual definition of laser-irradiated subcellular regions, with the ensuing restriction to only a small number of cells treated and analyzed in a single experiment. Here, we present an improved and versatile alternative to the micro-irradiation approach: Quantitative analysis of photo-manipulated samples using innovative settings of standard laser-scanning microscopes. Up to 200 cells are simultaneously exposed to a laser beam in a defined pattern of collinear rays. The induced striation pattern is then automatically evaluated by a simple algorithm, which provides a quantitative assessment of various laser-induced phenotypes in live or fixed cells. Overall, this new approach represents a more robust alternative to existing techniques, and provides a versatile tool for a wide range of applications in biomedicine. PMID:26777522

Microalbuminuria in obese patients with or without hypertension.

PubMed

Valensi, P; Assayag, M; Busby, M; Pariès, J; Lormeau, B; Attali, J R

1996-06-01

To evaluate the prevalence in obese patients of an increased urinary albumin excretion rate (UAER) and the factors involved in this parameter. Two hundred and seven nondiabetic obese patients with BMI = 34.7 +/- 5.7 (SD) kg/m2. None had proteinuria or a history of nephropathy or uropathy. Fifty-two had moderate hypertension. A control group of 22 lean healthy subjects was also studied. The UAER was determined from 24-h urine samples by means of immunonephelemetry laser method. Creatinine clearance was calculated. Glycemia and plasma C peptide at fasting and 120 mine after glucose oral administration, HbA1c, serum fructosamine, plasma total cholesterol and triglycerides, HDL and LDL cholesterol were measured. Food intakes were determined by dietary history. Compared with the control group, the UAER was significantly higher in the obese patients (18.0 +/- 20.1 mg/24 h vs 3.2 +/- 2.8 mg/24 h, P < 0.0001). It was elevated (> 30 mg/24 h) in 25 obese patients (12.1%) and in particular, in 19.2% of the obese patients with hypertension. It was significantly higher in the patients with android or mixed (both android and gynoid) obesity than in those with gynoid obesity (p = 0.050). Log UAER correlated negatively with the duration of hypertension (p = 0.038) and was higher in the patients with familial hypertension than in those without (p = 0.002). Log UAER correlated strongly with log creatinine clearance (p < 0.0001) and fractional albumin clearance (p < 0.0001). It correlated significantly with fasting and 120 min after glucose plasma C peptide concentrations (p = 0.018 and p = 0.046, respectively). Creatinine clearance was significantly higher in the patients with android or mixed obesity than in those with gynoid obesity (p = 0.001). Log creatinine clearance correlated negatively with age (p = 0.046), and log LDL cholesterol (p = 0.025) and positively with log lipid caloric intake (p = 0.014). These results show the high prevalence of microalbuminuria in nondiabetic obese patients and suggest the involvement of renal hyperfiltration. Microalbuminuria may be an indicator of familial hypertension in obese subjects. Insulin resistance may be involved in the increase in the UAER. Nutritional factors, particularly lipid intake, may contribute to this increase in the UAER via an increase in glomerular hyperfiltration.

Clinical assessment of a new 755 nm diode laser for hair removal: Efficacy, safety and practicality in 56 patients.

PubMed

Royo, Josefina; Moreno-Moraga, Javier; Trelles, Mario A

2017-04-01

Recently, the first diode laser with a wavelength of 755 nm for in-motion hair removal came on the market. The objective of this study was to check its efficacy, safety, and practicality under different options for its use. A prospective study in a heterogeneous group of 56 patients who had hair removed from various areas of their bodies using three different treatment methods. Four sessions were scheduled in all cases, with a gap of 3 months between each session. Efficacy was assessed by counting of hairs per cm 2 and the adverse effects in each session were recorded in detail in the patients' clinical histories. The three tested options achieved a significant reduction in the number of hairs (P < 0.0001). The average clearances achieved using the conventional method (HR), the in-motion method (SHR) and the stacking method were 75.5%, 70.1%, and 41.9%, respectively. The degree of satisfaction of the participants on a scale of 0-10 was 7.7, 8.1 and 6.8, respectively. Erythema and perifollicular edema, which are characteristic responses in laser hair removal, were observed. The incidence of burns was 1.33%. The 755-nm diode laser performed efficiently and safely in all the tested areas, using high total accumulated energy per surface unit. Based on our prior experience with other equipment, the results are promising. Lasers Surg. Med. 49:355-360, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Automatic Detection and Classification of Pole-Like Objects for Urban Cartography Using Mobile Laser Scanning Data

PubMed Central

Ordóñez, Celestino; Cabo, Carlos; Sanz-Ablanedo, Enoc

2017-01-01

Mobile laser scanning (MLS) is a modern and powerful technology capable of obtaining massive point clouds of objects in a short period of time. Although this technology is nowadays being widely applied in urban cartography and 3D city modelling, it has some drawbacks that need to be avoided in order to strengthen it. One of the most important shortcomings of MLS data is concerned with the fact that it provides an unstructured dataset whose processing is very time-consuming. Consequently, there is a growing interest in developing algorithms for the automatic extraction of useful information from MLS point clouds. This work is focused on establishing a methodology and developing an algorithm to detect pole-like objects and classify them into several categories using MLS datasets. The developed procedure starts with the discretization of the point cloud by means of a voxelization, in order to simplify and reduce the processing time in the segmentation process. In turn, a heuristic segmentation algorithm was developed to detect pole-like objects in the MLS point cloud. Finally, two supervised classification algorithms, linear discriminant analysis and support vector machines, were used to distinguish between the different types of poles in the point cloud. The predictors are the principal component eigenvalues obtained from the Cartesian coordinates of the laser points, the range of the Z coordinate, and some shape-related indexes. The performance of the method was tested in an urban area with 123 poles of different categories. Very encouraging results were obtained, since the accuracy rate was over 90%. PMID:28640189

Image-Guided Biopsy in the Esophagus through Comprehensive Optical Frequency Domain Imaging and Laser Marking: A Study in Living Swine

PubMed Central

Suter, Melissa J.; Jillella, Priyanka A.; Vakoc, Benjamin J.; Halpern, Elkan F.; Mino-Kenudson, Mari; Lauwers, Gregory Y.; Bouma, Brett E.; Nishioka, Norman S.; Tearney, Guillermo J.

2010-01-01

Background Random biopsy esophageal surveillance can be subject to sampling errors, resulting in diagnostic uncertainty. Optical frequency domain imaging (OFDI) is a high-speed, three-dimensional endoscopic microscopy technique. When deployed through a balloon-centering catheter, OFDI can automatically image the entire distal esophagus (6.0 cm length) in approximately 2 minutes. Objective To test a new platform for guided biopsy that allows the operator to select target regions of interest on an OFDI dataset, and then use a laser to mark the esophagus at corresponding locations. The specific goals include determining the optimal laser parameters, testing the accuracy of the laser marking process, evaluating the endoscopic visibility of the laser marks, and assessing the amount of mucosal damage produced by the laser. Design Experimental study conducted in five swine in vivo. Setting Massachusetts General Hospital. Main Outcome Measurements Success rate, including endoscopic visibility of laser marks and accuracy of the laser marking process for selected target sites, and extent of the thermal damage caused by the laser marks. Results All of the laser-induced marks were visible by endoscopy. Target locations were correctly marked with a success rate of 97.07% (95% CI, 89.8%-99.7%). Thermal damage was limited to the superficial layers of the mucosa and was observed to partially heal within 2 days. Limitations An animal study with artificially placed targets to simulate pathology. Conclusions The study demonstrates that laser marking of esophageal sites identified in comprehensive OFDI datasets is feasible and can be performed with sufficient accuracy, precision, and visibility to guide biopsy in vivo. PMID:19879573

Catastrophic optical bulk degradation (COBD) in high-power single- and multi-mode InGaAs-AlGaAs strained quantum well lasers

NASA Astrophysics Data System (ADS)

Sin, Yongkun; Lingley, Zachary; Brodie, Miles; Presser, Nathan; Moss, Steven C.

2017-02-01

High-power single-mode (SM) and multi-mode (MM) InGaAs-AlGaAs strained quantum well (QW) lasers are critical components for both telecommunications and space satellite communications systems. However, little has been reported on failure modes and degradation mechanisms of high-power SM and MM InGaAs-AlGaAs strained QW lasers although it is crucial to understand failure modes and underlying degradation mechanisms in developing these lasers that meet lifetime requirements for space satellite systems, where extremely high reliability of these lasers is required. Our present study addresses the aforementioned issues by performing long-term life-tests followed by failure mode analysis (FMA) and physics of failure investigation. We performed long-term accelerated life-tests on state-of-the-art SM and MM InGaAs-AlGaAs strained QW lasers under ACC (automatic current control) mode. Our life-tests have accumulated over 25,000 test hours for SM lasers and over 35,000 test hours for MM lasers. FMA was performed on failed SM lasers using electron beam induced current (EBIC). This technique allowed us to identify failure types by observing dark line defects. All the SM failures we studied showed catastrophic and sudden degradation and all of these failures were bulk failures. Our group previously reported that bulk failure or COBD (catastrophic optical bulk damage) is the dominant failure mode of MM InGaAs-AlGaAs strained QW lasers. Since degradation mechanisms responsible for COBD are still not well understood, we also employed other techniques including focused ion beam (FIB) processing and high-resolution TEM to further study dark line defects and dislocations in post-aged lasers. Our long-term life-test results and FMA results are reported.

Quantitative in vivo studies of hyperemia in the course of the tissue response to biomaterial implantation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bouet, T.; Schmitt, M.; Desuzinges, C.

1990-11-01

Hyperemia associated with an inflammatory response has been investigated in rats, by using four different experimental models, i.e., positive and negative polymer implants from the pharmacopea, operative control, and abscess induced by turpentine oil. 133Xenon clearance, infrared thermography and Laser Doppler Flowmetry (LDF) were used to monitor the subcutaneous local hemodynamic changes from 1 to 40 postoperative days. LDF proved to be a sensitive, reproducible method, able to discriminate positive from negative implants already at the 3rd postoperative day and up to 40 days. This increased local blood flow was also visualized at the site of positive implants at themore » 14th and 21st postoperative days by means of 133Xe Clearance. Additional information obtained by infrared thermography allowed discrimination between positive implants and control sites but only at the very early stage (1 to 3 days). The significance of the different data collected by the three techniques was correlated with histological events occurring at the different implant sites. LDF may therefore represent a useful technique for noninvasive semiquantitative assessment of tissue response to biomaterials.« less

Entropy-Based Registration of Point Clouds Using Terrestrial Laser Scanning and Smartphone GPS.

PubMed

Chen, Maolin; Wang, Siying; Wang, Mingwei; Wan, Youchuan; He, Peipei

2017-01-20

Automatic registration of terrestrial laser scanning point clouds is a crucial but unresolved topic that is of great interest in many domains. This study combines terrestrial laser scanner with a smartphone for the coarse registration of leveled point clouds with small roll and pitch angles and height differences, which is a novel sensor combination mode for terrestrial laser scanning. The approximate distance between two neighboring scan positions is firstly calculated with smartphone GPS coordinates. Then, 2D distribution entropy is used to measure the distribution coherence between the two scans and search for the optimal initial transformation parameters. To this end, we propose a method called Iterative Minimum Entropy (IME) to correct initial transformation parameters based on two criteria: the difference between the average and minimum entropy and the deviation from the minimum entropy to the expected entropy. Finally, the presented method is evaluated using two data sets that contain tens of millions of points from panoramic and non-panoramic, vegetation-dominated and building-dominated cases and can achieve high accuracy and efficiency.

Design of high-brightness TEM00-mode solar-pumped laser for renewable material processing

NASA Astrophysics Data System (ADS)

Liang, D.; Almeida, J.

2014-08-01

The conversion of sunlight into laser light by direct solar pumping is of ever-increasing importance because broadband, temporally constant, sunlight is converted into laser light, which can be a source of narrowband, collimated, rapidly pulsed, radiation with the possibility of obtaining extremely high brightness and intensity. Nonlinear processes, such as harmonic generation, might be used to obtain broad wavelength coverage, including the ultraviolet wavelengths, where the solar flux is very weak. The direct excitation of large lasers by sunlight offers the prospect of a drastic reduction in the cost of coherent optical radiation for high average power materials processing. This renewable laser has a large potential for many applications such as high-temperature materials processing, renewable magnesium-hydrogen energy cycle and so on. We propose here a scalable TEM00 mode solar laser pumping scheme, which is composed of four firststage 1.13 m diameter Fresnel lenses with its respective folding mirrors mounted on a two-axis automatic solar tracker. Concentrated solar power at the four focal spots of these Fresnel lenses are focused individually along a common 3.5 mm diameter, 70 mm length Nd:YAG rod via four pairs of second-stage fused-silica spherical lenses and third-stage 2D-CPCs (Compound Parabolic Concentrator), sitting just above the laser rod which is also double-pass pumped by four V-shaped pumping cavities. Distilled water cools both the rod and the concentrators. 15.4 W TEM00 solar laser power is numerically calculated, corresponding to 6.7 times enhancement in laser beam brightness.

Automatic detection of diabetic retinopathy features in ultra-wide field retinal images

NASA Astrophysics Data System (ADS)

Levenkova, Anastasia; Sowmya, Arcot; Kalloniatis, Michael; Ly, Angelica; Ho, Arthur

2017-03-01

Diabetic retinopathy (DR) is a major cause of irreversible vision loss. DR screening relies on retinal clinical signs (features). Opportunities for computer-aided DR feature detection have emerged with the development of Ultra-WideField (UWF) digital scanning laser technology. UWF imaging covers 82% greater retinal area (200°), against 45° in conventional cameras3 , allowing more clinically relevant retinopathy to be detected4 . UWF images also provide a high resolution of 3078 x 2702 pixels. Currently DR screening uses 7 overlapping conventional fundus images, and the UWF images provide similar results1,4. However, in 40% of cases, more retinopathy was found outside the 7-field ETDRS) fields by UWF and in 10% of cases, retinopathy was reclassified as more severe4 . This is because UWF imaging allows examination of both the central retina and more peripheral regions, with the latter implicated in DR6 . We have developed an algorithm for automatic recognition of DR features, including bright (cotton wool spots and exudates) and dark lesions (microaneurysms and blot, dot and flame haemorrhages) in UWF images. The algorithm extracts features from grayscale (green "red-free" laser light) and colour-composite UWF images, including intensity, Histogram-of-Gradient and Local binary patterns. Pixel-based classification is performed with three different classifiers. The main contribution is the automatic detection of DR features in the peripheral retina. The method is evaluated by leave-one-out cross-validation on 25 UWF retinal images with 167 bright lesions, and 61 other images with 1089 dark lesions. The SVM classifier performs best with AUC of 94.4% / 95.31% for bright / dark lesions.

Empirical study on neural network based predictive techniques for automatic number plate recognition

NASA Astrophysics Data System (ADS)

Shashidhara, M. S.; Indrakumar, S. S.

2011-10-01

The objective of this study is to provide an easy, accurate and effective technology for the Bangalore city traffic control. This is based on the techniques of image processing and laser beam technology. The core concept chosen here is an image processing technology by the method of automatic number plate recognition system. First number plate is recognized if any vehicle breaks the traffic rules in the signals. The number is fetched from the database of the RTO office by the process of automatic database fetching. Next this sends the notice and penalty related information to the vehicle owner email-id and an SMS sent to vehicle owner. In this paper, we use of cameras with zooming options & laser beams to get accurate pictures further applied image processing techniques such as Edge detection to understand the vehicle, Identifying the location of the number plate, Identifying the number plate for further use, Plain plate number, Number plate with additional information, Number plates in the different fonts. Accessing the database of the vehicle registration office to identify the name and address and other information of the vehicle number. The updates to be made to the database for the recording of the violation and penalty issues. A feed forward artificial neural network is used for OCR. This procedure is particularly important for glyphs that are visually similar such as '8' and '9' and results in training sets of between 25,000 and 40,000 training samples. Over training of the neural network is prevented by Bayesian regularization. The neural network output value is set to 0.05 when the input is not desired glyph, and 0.95 for correct input.

Fluorescence measurement of diode (805 nm) laser-induced release of 5,6-CF from DSPC liposomes for monitoring of temperature: an in vivo study in rat liver using indocyanine green potentiation

NASA Astrophysics Data System (ADS)

Mordon, Serge R.; Desmettre, Thomas; Devoisselle, Jean-Marie; Soulie-Begu, Sylvie

1995-05-01

This in-vivo study examines the validity of fluorescence measurement of laser-induced release of temperature sensitive liposome-encapsulated dye for monitoring of temperature and prediction of tissue thermal damage. It is performed in rat liver after i.v. injection of liposomes loaded with a fluorescent dye and i.v. injection of Indocyanine Green (ICG) for diode laser potentiation. Temperature sensitive liposomes (DSPC: Di- Stearoyl-Phosphatidyl-Choline) are loaded with 5,6-Carboxyfluorescein (5,6-CF). These liposomes (1.5 ml solution) and ICG (1.5 ml solution-5 mg/kg) are injected to adult male wistar rats. Two hours later, the liver is exposed and irradiated with a 0.8 W diode laser using pulses lasting from 1 s to 6 s (fluence ranging from 16 to 98 J/cm+2)). Simultaneously, the fluorescence emission is measured with a fluorescent imaging system. Results show that the fluorescence intensity increases linearly form 18 J/cm2 up to 75 J/cm2. These fluences correspond to surface temperatures between 42°C to 64°C. The measurements appear to be highly reproducible. In this temperature range, the accuracy is +/- 3°C. The maximum intensity is observed immediately after the laser is switched off and a decrease of the fluorescence intensity is observed (27% in 20 minutes) due to the 5.6-CF clearance. However, the ratio (IF/Ibck) remains almost stable over this period of time and the determination of the temperature is still possible with a good accuracy even 20 minutes after laser irradiation. In conclusion, temperature monitoring by using fluorescence measurement of laser-induced release of liposome-encapsulated dye is clearly demonstrated. This procedure could conceivably prove useful for controlling the thermal coagulation of biological tissues.

Generation-V dual-Purkinje-image eyetracker

NASA Technical Reports Server (NTRS)

Crane, H. D.; Steele, C. M.

1985-01-01

Major advances characterize the Generation-V dual-Purkinje-image eyetracker compared with the Generation-III version previously described. These advances include a large reduction in size, major improvements in frequency response and noise level, automatic alignment to a subject, and automatic adjustment for different separation between the visual and optic axes, which can vary considerably from subject to subject. In a number of applications described in the paper, the eyetracker is coupled with other highly specialized optical devices. These applications include accurately stabilizing an image on a subject's retina; accurately simulating a visually dead retinal region (i.e., a scotoma) of arbitrary shape, size, and position; and, for clinical purposes, stabilizing the position of a laser coagulator beam on a patient's retina so that the point of contact is unaffected by the patient's own eye movements.

A Computer-Controlled Laser Bore Scanner

NASA Astrophysics Data System (ADS)

Cheng, Charles C.

1980-08-01

This paper describes the design and engineering of a laser scanning system for production applications. The laser scanning techniques, the timing control, the logic design of the pattern recognition subsystem, the digital computer servo control for the loading and un-loading of parts, and the laser probe rotation and its synchronization will be discussed. The laser inspection machine is designed to automatically inspect the surface of precision-bored holes, such as those in automobile master cylinders, without contacting the machined surface. Although the controls are relatively sophisticated, operation of the laser inspection machine is simple. A laser light beam from a commercially available gas laser, directed through a probe, scans the entire surface of the bore. Reflected light, picked up through optics by photoelectric sensors, generates signals that are fed to a mini-computer for processing. A pattern recognition techniques program in the computer determines acceptance or rejection of the part being inspected. The system's acceptance specifications are adjustable and are set to the user's established tolerances. However, the computer-controlled laser system is capable of defining from 10 to 75 rms surface finish, and voids or flaws from 0.0005 to 0.020 inch. Following the successful demonstration with an engineering prototype, the described laser machine has proved its capability to consistently ensure high-quality master brake cylinders. It thus provides a safety improvement for the automotive braking system. Flawless, smooth cylinder bores eliminate premature wearing of the rubber seals, resulting in a longer-lasting master brake cylinder and a safer and more reliable automobile. The results obtained from use of this system, which has been in operation about a year for replacement of a tedious, manual operation on one of the high-volume lines at the Bendix Hydraulics Division, have been very satisfactory.

New Navy Fighting Machine in the South China Sea

DTIC Science & Technology

2012-06-01

documents/SD_WhitePaper_Mil6. pdf . Rubel, Robert C. "The Future of the Aircraft Carrier." Naval War College Review, Autumn 2011, http:// www.usnwc.edu...50 Figure 8. CT USV Disbursement Amongst Combatants Tactic...51 Figure 9. FALCON Laser Node Affixed to DC-3 Aircraft ...Area Denial AAC Air-to-Air Combat AAD Anti- Aircraft Defense AGC Automatic Gain Control AGS Advanced Gun System ARIES Airborne Reconnaissance

Manufacturing Methods and Technology Program for Ruggedized Tactical Fiber Optic Cable.

DTIC Science & Technology

1979-10-26

cores manufactured on this unit since the improvements were incorporated. An automatic diameter control unit with a laser micrometer sensor has been...fiber optic sensor systems for the TACA-MO aircraft and power encoding, an 18-port single fiber data bus for the Autonetics information transfer...echnica del Estado, Santiago, Chile in 1958. He received a degree in Industrial Chemical Engineering from Escuela de Ingenieros Industriales , Santiago

Diffraction Pattern Analysis as an Optical Inspection Technique

DTIC Science & Technology

1991-08-01

BACKGROUND Diameters of fiber samples have commonly been measured manually with an optical microscope. Marcuse and Presby developed an automatic...by analyzing the back-scattered light when a beam of laser light impinged upon the fiber [2]. Presby and Marcuse extended this back-scattering tech...be im- proved further in order to become a feasible method for detecting a small number of blocked openings in CRT screens. 20 REFERENCES 1. Marcuse

Automatic diagnostic system for measuring ocular refractive errors

NASA Astrophysics Data System (ADS)

Ventura, Liliane; Chiaradia, Caio; de Sousa, Sidney J. F.; de Castro, Jarbas C.

1996-05-01

Ocular refractive errors (myopia, hyperopia and astigmatism) are automatic and objectively determined by projecting a light target onto the retina using an infra-red (850 nm) diode laser. The light vergence which emerges from the eye (light scattered from the retina) is evaluated in order to determine the corresponding ametropia. The system basically consists of projecting a target (ring) onto the retina and analyzing the scattered light with a CCD camera. The light scattered by the eye is divided into six portions (3 meridians) by using a mask and a set of six prisms. The distance between the two images provided by each of the meridians, leads to the refractive error of the referred meridian. Hence, it is possible to determine the refractive error at three different meridians, which gives the exact solution for the eye's refractive error (spherical and cylindrical components and the axis of the astigmatism). The computational basis used for the image analysis is a heuristic search, which provides satisfactory calculation times for our purposes. The peculiar shape of the target, a ring, provides a wider range of measurement and also saves parts of the retina from unnecessary laser irradiation. Measurements were done in artificial and in vivo eyes (using cicloplegics) and the results were in good agreement with the retinoscopic measurements.

Quality assurance in the production of pipe fittings by automatic laser-based material identification

NASA Astrophysics Data System (ADS)

Moench, Ingo; Peter, Laszlo; Priem, Roland; Sturm, Volker; Noll, Reinhard

1999-09-01

In plants of the chemical, nuclear and off-shore industry, application specific high-alloyed steels are used for pipe fittings. Mixing of different steel grades can lead to corrosion with severe consequential damages. Growing quality requirements and environmental responsibilities demand a 100% material control in the production of the pipe fittings. Therefore, LIFT, an automatic inspection machine, was developed to insure against any mix of material grades. LIFT is able to identify more than 30 different steel grades. The inspection method is based on Laser-Induced Breakdown Spectrometry (LIBS). An expert system, which can be easily trained and recalibrated, was developed for the data evaluation. The result of the material inspection is transferred to an external handling system via a PLC interface. The duration of the inspection process is 2 seconds. The graphical user interface was developed with respect to the requirements of an unskilled operator. The software is based on a realtime operating system and provides a safe and reliable operation. An interface for the remote maintenance by modem enables a fast operational support. Logged data are retrieved and evaluated. This is the basis for an adaptive improvement of the configuration of LIFT with respect to changing requirements in the production line. Within the first six months of routine operation, about 50000 pipe fittings were inspected.

Simultaneous Detection and Tracking of Pedestrian from Panoramic Laser Scanning Data

NASA Astrophysics Data System (ADS)

Xiao, Wen; Vallet, Bruno; Schindler, Konrad; Paparoditis, Nicolas

2016-06-01

Pedestrian traffic flow estimation is essential for public place design and construction planning. Traditional data collection by human investigation is tedious, inefficient and expensive. Panoramic laser scanners, e.g. Velodyne HDL-64E, which scan surroundings repetitively at a high frequency, have been increasingly used for 3D object tracking. In this paper, a simultaneous detection and tracking (SDAT) method is proposed for precise and automatic pedestrian trajectory recovery. First, the dynamic environment is detected using two different methods, Nearest-point and Max-distance. Then, all the points on moving objects are transferred into a space-time (x, y, t) coordinate system. The pedestrian detection and tracking amounts to assign the points belonging to pedestrians into continuous trajectories in space-time. We formulate the point assignment task as an energy function which incorporates the point evidence, trajectory number, pedestrian shape and motion. A low energy trajectory will well explain the point observations, and have plausible trajectory trend and length. The method inherently filters out points from other moving objects and false detections. The energy function is solved by a two-step optimization process: tracklet detection in a short temporal window; and global tracklet association through the whole time span. Results demonstrate that the proposed method can automatically recover the pedestrians trajectories with accurate positions and low false detections and mismatches.

Integrating machine learning to achieve an automatic parameter prediction for practical continuous-variable quantum key distribution

NASA Astrophysics Data System (ADS)

Liu, Weiqi; Huang, Peng; Peng, Jinye; Fan, Jianping; Zeng, Guihua

2018-02-01

For supporting practical quantum key distribution (QKD), it is critical to stabilize the physical parameters of signals, e.g., the intensity, phase, and polarization of the laser signals, so that such QKD systems can achieve better performance and practical security. In this paper, an approach is developed by integrating a support vector regression (SVR) model to optimize the performance and practical security of the QKD system. First, a SVR model is learned to precisely predict the time-along evolutions of the physical parameters of signals. Second, such predicted time-along evolutions are employed as feedback to control the QKD system for achieving the optimal performance and practical security. Finally, our proposed approach is exemplified by using the intensity evolution of laser light and a local oscillator pulse in the Gaussian modulated coherent state QKD system. Our experimental results have demonstrated three significant benefits of our SVR-based approach: (1) it can allow the QKD system to achieve optimal performance and practical security, (2) it does not require any additional resources and any real-time monitoring module to support automatic prediction of the time-along evolutions of the physical parameters of signals, and (3) it is applicable to any measurable physical parameter of signals in the practical QKD system.

The Iqmulus Urban Showcase: Automatic Tree Classification and Identification in Huge Mobile Mapping Point Clouds

NASA Astrophysics Data System (ADS)

Böhm, J.; Bredif, M.; Gierlinger, T.; Krämer, M.; Lindenberg, R.; Liu, K.; Michel, F.; Sirmacek, B.

2016-06-01

Current 3D data capturing as implemented on for example airborne or mobile laser scanning systems is able to efficiently sample the surface of a city by billions of unselective points during one working day. What is still difficult is to extract and visualize meaningful information hidden in these point clouds with the same efficiency. This is where the FP7 IQmulus project enters the scene. IQmulus is an interactive facility for processing and visualizing big spatial data. In this study the potential of IQmulus is demonstrated on a laser mobile mapping point cloud of 1 billion points sampling ~ 10 km of street environment in Toulouse, France. After the data is uploaded to the IQmulus Hadoop Distributed File System, a workflow is defined by the user consisting of retiling the data followed by a PCA driven local dimensionality analysis, which runs efficiently on the IQmulus cloud facility using a Spark implementation. Points scattering in 3 directions are clustered in the tree class, and are separated next into individual trees. Five hours of processing at the 12 node computing cluster results in the automatic identification of 4000+ urban trees. Visualization of the results in the IQmulus fat client helps users to appreciate the results, and developers to identify remaining flaws in the processing workflow.

Automatic Detection of Storm Damages Using High-Altitude Photogrammetric Imaging

NASA Astrophysics Data System (ADS)

Litkey, P.; Nurminen, K.; Honkavaara, E.

2013-05-01

The risks of storms that cause damage in forests are increasing due to climate change. Quickly detecting fallen trees, assessing the amount of fallen trees and efficiently collecting them are of great importance for economic and environmental reasons. Visually detecting and delineating storm damage is a laborious and error-prone process; thus, it is important to develop cost-efficient and highly automated methods. Objective of our research project is to investigate and develop a reliable and efficient method for automatic storm damage detection, which is based on airborne imagery that is collected after a storm. The requirements for the method are the before-storm and after-storm surface models. A difference surface is calculated using two DSMs and the locations where significant changes have appeared are automatically detected. In our previous research we used four-year old airborne laser scanning surface model as the before-storm surface. The after-storm DSM was provided from the photogrammetric images using the Next Generation Automatic Terrain Extraction (NGATE) algorithm of Socet Set software. We obtained 100% accuracy in detection of major storm damages. In this investigation we will further evaluate the sensitivity of the storm-damage detection process. We will investigate the potential of national airborne photography, that is collected at no-leaf season, to automatically produce a before-storm DSM using image matching. We will also compare impact of the terrain extraction algorithm to the results. Our results will also promote the potential of national open source data sets in the management of natural disasters.

[Impact of low level laser therapy on skin blood flow].

PubMed

Podogrodzki, Jacek; Lebiedowski, Michał; Szalecki, Mieczysław; Kępa, Izabela; Syczewska, Małgorzata; Jóźwiak, Sergiusz

2016-01-01

The aim of this study was to objectively assess the impact of low level laser therapy on skin blood flow, in terms of two of its components - the flow and trophic and therapeutic effect. Nineteen children aged 3-15 years have been included in the study (seven boys and twelve girls) with a diagnosis of meningomyelocele in the lumbosacral area. In nine of them (47.3%) bedsores were found in the area of paresis location. Studies of skin blood flow were performed using xenon 133 clearance in the Department of Nuclear Medicine of the Children's Memorial Health Institute. Xenon 133 radioisotope in saline with intrinsic activity 74 MBq in 1 ml was used as the marker. Laser application was performed immediately prior to the application of the marker with a tag shower 60 mW probe, emitting 680 nm red light with surface power density of 0.5 J/cm2. Within the tested children the laser application resulted in a significantly increased skin blood flow. Average results in tested group before LLLT are 7.47 ml/100 g/min, after LLLT 11.08 ml/100 g/min. 1. LLLT significantly increases the perfusion of the skin. 2. The effect of the increased perfusion as the result of laserotherapy in the most evident in children with skin trophic abnormalities. 3. Results confirmed by clinical observation indicate, that perfusion increase in relation to LLLT takes place with participation of trophic component of skin blood circulation.

Percutaneous endoscopic holmium laser lithotripsy for management of complicated biliary calculi.

PubMed

Healy, Kelly; Chamsuddin, Abbas; Spivey, James; Martin, Louis; Nieh, Peter; Ogan, Kenneth

2009-01-01

Advances in endoscopic techniques have transformed the management of urolithiasis. We sought to evaluate the role of such urological interventions for the treatment of complex biliary calculi. We conducted a retrospective review of all patients (n=9) undergoing percutaneous holmium laser lithotripsy for complicated biliary calculi over a 4-year period (12/2003 to 12/2007). All previously failed standard techniques include ERCP with sphincterotomy (n=6), PTHC (n=7), or both of these. Access to the biliary system was obtained via an existing percutaneous transhepatic catheter or T-tube tracts. Endoscopic holmium laser lithotripsy was performed via a flexible cystoscope or ureteroscope. Stone clearance was confirmed intra- and post-operatively. A percutaneous transhepatic drain was left indwelling for follow-up imaging. Mean patient age was 65.6 years (range, 38 to 92). Total stone burden ranged from 1.7 cm to 5 cm. All 9 patients had stones located in the CBD, with 2 patients also having additional stones within the hepatic ducts. All 9 patients (100%) were visually stone-free after one endoscopic procedure. No major perioperative complications occurred. Mean length of stay was 2.4 days. At a mean radiological follow-up of 5.4 months (range, 0.5 to 21), no stone recurrence was noted. Percutaneous endoscopic holmium laser lithotripsy is a minimally invasive alternative to open salvage surgery for complex biliary calculi refractory to standard approaches. This treatment is both safe and efficacious. Success depends on a multidisciplinary approach.

Percutaneous Endoscopic Holmium Laser Lithotripsy for Management of Complicated Biliary Calculi

PubMed Central

Healy, Kelly; Chamsuddin, Abbas; Spivey, James; Martin, Louis; Nieh, Peter

2009-01-01

Background and Objectives: Advances in endoscopic techniques have transformed the management of urolithiasis. We sought to evaluate the role of such urological interventions for the treatment of complex biliary calculi. Methods: We conducted a retrospective review of all patients (n=9) undergoing percutaneous holmium laser lithotripsy for complicated biliary calculi over a 4-year period (12/2003 to 12/2007). All previously failed standard techniques include ERCP with sphincterotomy (n=6), PTHC (n=7), or both of these. Access to the biliary system was obtained via an existing percutaneous transhepatic catheter or T-tube tracts. Endoscopic holmium laser lithotripsy was performed via a flexible cystoscope or ureteroscope. Stone clearance was confirmed intra- and postoperatively. A percutaneous transhepatic drain was left indwelling for follow-up imaging. Results: Mean patient age was 65.6 years (range, 38 to 92). Total stone burden ranged from 1.7 cm to 5 cm. All 9 patients had stones located in the CBD, with 2 patients also having additional stones within the hepatic ducts. All 9 patients (100%) were visually stone-free after one endoscopic procedure. No major perioperative complications occurred. Mean length of stay was 2.4 days. At a mean radiological follow-up of 5.4 months (range, 0.5 to 21), no stone recurrence was noted. Conclusions: Percutaneous endoscopic holmium laser lithotripsy is a minimally invasive alternative to open salvage surgery for complex biliary calculi refractory to standard approaches. This treatment is both safe and efficacious. Success depends on a multidisciplinary approach. PMID:19660213

Vision and spectroscopic sensing for joint tracing in narrow gap laser butt welding

NASA Astrophysics Data System (ADS)

Nilsen, Morgan; Sikström, Fredrik; Christiansson, Anna-Karin; Ancona, Antonio

2017-11-01

The automated laser beam butt welding process is sensitive to positioning the laser beam with respect to the joint because a small offset may result in detrimental lack of sidewall fusion. This problem is even more pronounced in case of narrow gap butt welding, where most of the commercial automatic joint tracing systems fail to detect the exact position and size of the gap. In this work, a dual vision and spectroscopic sensing approach is proposed to trace narrow gap butt joints during laser welding. The system consists of a camera with suitable illumination and matched optical filters and a fast miniature spectrometer. An image processing algorithm of the camera recordings has been developed in order to estimate the laser spot position relative to the joint position. The spectral emissions from the laser induced plasma plume have been acquired by the spectrometer, and based on the measurements of the intensities of selected lines of the spectrum, the electron temperature signal has been calculated and correlated to variations of process conditions. The individual performances of these two systems have been experimentally investigated and evaluated offline by data from several welding experiments, where artificial abrupt as well as gradual deviations of the laser beam out of the joint were produced. Results indicate that a combination of the information provided by the vision and spectroscopic systems is beneficial for development of a hybrid sensing system for joint tracing.

Validation of a new noniterative method for accurate position determination of a scanning laser vibrometer

NASA Astrophysics Data System (ADS)

Pauwels, Steven; Boucart, Nick; Dierckx, Benoit; Van Vlierberghe, Pieter

2000-05-01

The use of a scanning laser Doppler vibrometer for vibration testing is becoming a popular instrument. The scanning laser Doppler vibrometer is a non-contacting transducer that can measure many points at a high spatial resolution in a short time. Manually aiming the laser beam at the points that need to be measured is very time consuming. In order to use it effectively, the position of the laser Doppler vibrometer needs to be determined relative to the structure. If the position of the laser Doppler vibrometer is known, any visible point on the structure can be hit and measured automatically. A new algorithm for this position determination is developed, based on a geometry model of the structure. After manually aiming the laser beam at 4 or more known points, the laser position and orientation relative to the structure is determined. Using this calculated position and orientation a list with the mirror angles for every measurement point is generated, which is used during the measurement. The algorithm is validated using 3 practical cases. In the first case a plate is used of which the points are measured very accurately, so the geometry model is assumed to be perfect. The second case is a brake disc. Here the geometry points are measured with a ruler, thus not so accurate. The final validation is done on a body in white of a car. A reduced finite element model is used as geometry model. This calibration shows that the new algorithm is very effective and practically usable.

Coherent Doppler lidar for automated space vehicle, rendezvous, station-keeping and capture

NASA Technical Reports Server (NTRS)

Dunkin, James A.

1991-01-01

Recent advances in eye-safe, short wavelength solid-state lasers offer real potential for the development of compact, reliable, light-weight, efficient coherent lidar. Laser diode pumping of these devices has been demonstrated, thereby eliminating the need for flash lamp pumping, which has been a major drawback to the use of these lasers in space based applications. Also these lasers now have the frequency stability required to make them useful in coherent lidar, which offers all of the advantages of non-coherent lidar, but with the additional advantage that direct determination of target velocity is possible by measurement of the Doppler shift. By combining the Doppler velocity measurement capability with the inherent high angular resolution and range accuracy of lidar it is possible to construct Doppler images of targets for target motion assessment. A coherent lidar based on a Tm,Ho:YAG 2-micrometer wavelength laser was constructed and successfully field tested on atmospheric targets in 1990. This lidar incorporated an all solid state (laser diode pumped) master oscillator, in conjunction with a flash lamp pumped slave oscillator. Solid-state laser technology is rapidly advancing, and with the advent of high efficiency, high power, semiconductor laser diodes as pump sources, all-solid-state, coherent lidars are a real possibility in the near future. MSFC currently has a feasibility demonstration effort under way which will involve component testing, and preliminary design of an all-solid-state, coherent lidar for automatic rendezvous, and capture. This two year effort, funded by the Director's Discretionary Fund is due for completion in 1992.

Optical system for UV-laser technological equipment

NASA Astrophysics Data System (ADS)

Fedosov, Yuri V.; Romanova, Galina E.; Afanasev, Maxim Ya.

2017-09-01

Recently there has been an intensive development of intelligent industrial equipment that is highly automated and can be rapidly adjusted for certain details. This equipment can be robotics systems, automatic wrappers and markers, CNC machines and 3D printers. The work equipment considered is the system for selective curing of photopolymers using a UV-laser and UV-radiation in such equipment that leads to additional technical difficulties. In many cases for transporting the radiation from the laser to the point processed, a multi-mirror system is used: however, such systems are usually difficult to adjust. Additionally, such multi-mirror systems are usually used as a part of the equipment for laser cutting of metals using high-power IR-lasers. For the UV-lasers, using many mirrors leads to crucial radiation losses because of many reflections. Therefore, during the development of the optical system for technological equipment using UV-laser we need to solve two main problems: to transfer the radiation for the working point with minimum losses and to include the system for controlling/handling the radiation spot position. We introduce a system for working with UV-lasers with 450mW of power and a wavelength of 0.45 μm based on a fiber system. In our modelling and design, we achieve spot sizes of about 300 μm, and the designed optical and mechanical systems (prototypes) were manufactured and assembled. In this paper, we present the layout of the technological unit, the results of the theoretical modelling of some parts of the system and some experimental results.

Is gut the "motor" for producing hepatocellular dysfunction after trauma and hemorrhagic shock?

PubMed

Wang, P; Ba, Z F; Cioffi, W G; Bland, K I; Chaudry, I H

1998-02-01

Although studies suggest that the gut may be the "motor" responsible for producing sepsis and multiple organ failure after injury, it is not known whether enterectomy prior to the onset of hemorrhage alters proinflammatory cytokines TNF and IL-6 and, if so, whether hepatocellular dysfunction and damage are prevented or attenuated under such conditions. Under methoxyflurane anesthesia, an enterectomy in the rat was performed by excision of the duodenum, jejunum, and ileum. The rats were then bled to and maintained at a mean arterial pressure of 40 mm Hg until 40% of the maximal shed volume was returned in the form of Ringer's lactate. The animals were then resuscitated with four times the volume of shed blood with Ringer's lactate over 1 h. At 1.5 h after the completion of resuscitation, hepatocellular function [i.e., the maximal velocity (Vmax) and transport efficiency (Km) of indocyanine green (ICG) clearance] was assessed by an in vivo ICG clearance technique. Blood samples were taken for the measurement of TNF, IL-6, and liver enzymes (i.e., SGPT and SGOT). Cardiac output and microvascular blood flow were determined by ICG dilution and laser Doppler flowmetry, respectively. The increase in circulating levels of TNF but not IL-6 was prevented by enterectomy prior to hemorrhage. The reduced Vmax and K(m) and elevated SGPT and SGOT following hemorrhage and resuscitation, however, were not significantly affected by prior enterectomy. Moreover, enterectomy before hemorrhage further reduced hepatic perfusion. Since enterectomy prior to the onset of hemorrhage does not prevent or attenuate the reduced ICG clearance and elevated liver enzymes despite downregulation of TNF production, it appears that the small intestine does not play a significant role in producing hepatocellular dysfunction and injury following trauma and hemorrhagic shock.

3D Geometrical Inspection of Complex Geometry Parts Using a Novel Laser Triangulation Sensor and a Robot

PubMed Central

Brosed, Francisco Javier; Aguilar, Juan José; Guillomía, David; Santolaria, Jorge

2011-01-01

This article discusses different non contact 3D measuring strategies and presents a model for measuring complex geometry parts, manipulated through a robot arm, using a novel vision system consisting of a laser triangulation sensor and a motorized linear stage. First, the geometric model incorporating an automatic simple module for long term stability improvement will be outlined in the article. The new method used in the automatic module allows the sensor set up, including the motorized linear stage, for the scanning avoiding external measurement devices. In the measurement model the robot is just a positioning of parts with high repeatability. Its position and orientation data are not used for the measurement and therefore it is not directly “coupled” as an active component in the model. The function of the robot is to present the various surfaces of the workpiece along the measurement range of the vision system, which is responsible for the measurement. Thus, the whole system is not affected by the robot own errors following a trajectory, except those due to the lack of static repeatability. For the indirect link between the vision system and the robot, the original model developed needs only one first piece measuring as a “zero” or master piece, known by its accurate measurement using, for example, a Coordinate Measurement Machine. The strategy proposed presents a different approach to traditional laser triangulation systems on board the robot in order to improve the measurement accuracy, and several important cues for self-recalibration are explored using only a master piece. Experimental results are also presented to demonstrate the technique and the final 3D measurement accuracy. PMID:22346569

Design and development of a compact lidar/DIAL system for aerial surveillance of urban areas

NASA Astrophysics Data System (ADS)

Gaudio, P.; Gelfusa, M.; Malizia, A.; Richetta, M.; Antonucci, A.; Ventura, P.; Murari, A.; Vega, J.

2013-10-01

Recently surveying large areas in an automatic way, for early detection of harmful chemical agents, has become a strategic objective of defence and public health organisations. The Lidar-Dial techniques are widely recognized as a cost-effective alternative to monitor large portions of the atmosphere but, up to now, they have been mainly deployed as ground based stations. The design reported in this paper concerns the development of a Lidar-Dial system compact enough to be carried by a small airplane and capable of detecting sudden releases in air of harmful and/or polluting substances. The proposed approach consists of continuous monitoring of the area under surveillance with a Lidar type measurement. Once a significant increase in the density of backscattering substances is revealed, it is intended to switch to the Dial technique to identify the released chemicals and to determine its concentration. In this paper, the design of the proposed system is described and the simulations carried out to determine its performances are reported. For the Lidar measurements, commercially available Nd- YAG laser sources have already been tested and their performances, in combination with avalanche photodiodes, have been experimentally verified to meet the required specifications. With regard to the DIAL measurements, new compact CO2 laser sources are being investigated. The most promising candidate presents an energy per pulse of about 50 mJ typical, sufficient for a range of at least 500m. The laser also provides the so called "agile tuning" option that allows to quickly tune the wavelength. To guarantee continuous, automatic surveying of large areas, innovative solutions are required for the data acquisition, self monitoring of the system and data analysis. The results of the design, the simulations and some preliminary tests illustrate the potential of the chosen, integrated approach.

[Evaluation of YAG-laser vitreolysis effectiveness based on quantitative characterization of vitreous floaters].

PubMed

Shaimova, V A; Shaimov, T B; Shaimov, R B; Galin, A Yu; Goloshchapova, Zh A; Ryzhkov, P K; Fomin, A V

2018-01-01

To develop methods for evaluating effectiveness of YAG-laser vitreolysis of vitreous floaters. The study included 144 patients (173 eyes) who had underwent YAG-laser vitreolysis and were under observation from 01.09.16 to 31.01.18. The patients were 34 to 86 years old (mean age 62.7±10.2 years), 28 (19.4%) patients were male, 116 (80.6%) - female. All patients underwent standard and additional examination: ultrasonography (Accutome B-scan plus, U.S.A.), optic biometry (Lenstar 900, Haag-Streit, Switzerland), spectral optical coherence tomography using RTVue XR Avanti scanner (Optovue, U.S.A.) in modes Enhanced HD Line, 3D Retina, 3D Widefield MCT, Cross Line, Angio Retina, and scanning laser ophthalmoscopy (SLO) using Navilas 577s system. Laser vitreolysis was performed using the Ultra Q Reflex laser (Ellex, Australia). This paper presents methods of objective quantitative and qualitative assessment of artifactual shadows of vitreous floaters with spectral optical coherence tomographic scanner RTVue xR Avanti employing an algorithm of automatic detection of non-perfusion zones in modes Angio Retina, HD Angio Retina, as well as foveal avascular zone (FAZ) measurement with Angio Analytics® software. SLO performed with Navilas 577s was used as method of visualizing floaters and artifactual shadows in retinal surface layers prior to surgical treatment and after YAG-laser vitreolysis. Suggested methods of quantitative and qualitative assessment of artifactual shadows of the floaters in retinal layers are promising and may prove to be highly relevant for clinical monitoring of patients, optimization of treatment indications and evaluating effectiveness of YAG-laser vitreolysis. Further research of laser vitreolysis effectiveness in patients with vitreous floaters is necessary.

Bringing PW-class lasers to XFELs (Conference Presentation)

NASA Astrophysics Data System (ADS)

Tomizawa, Hiromitsu

2017-06-01

Experimental researches using high power optical lasers combined with free electron lasers (FELs) open new frontiers in high energy density (HED) sciences. Probing and pumping capabilities are dramatically improved due to the brightness of the XFEL pulses with ultrafast duration. Besides, the peak intensities of Ti:sapphire laser Chirped Pulse Amplification (CPA) systems reach petawatt (PW)-class with operating in few tens of fs and commercially available at a few Hz of repetition rate. We have been developing an experimental platform for HED sciences using high power, high intensity optical lasers at the XFEL facility, SACLA.Currently, an experimental platform with a dual 0.5 PW Ti:Sapphire laser system is under beam commissioning for experiments combined with the SACLA's x-ray beam for research objectives that require more peak power in the optical laser pulses with a few tens of fs. The optical laser system is designed to deliver two laser beams simultaneously with the maximum power of 0.5 PW in each into a target chamber located in an experimental hutch 6 (EH6) at BL2, which was recently commissioned as a SACLA's 2nd hard x-ray beamline. A focusing capability using sets of compound refractive lenses will be applied to increase the x-ray fluence on the target sample. One of the most key issues for the integrated experimental platform is development of diagnostics that meets requirements both from the high power laser (e.g. resistance to harsh environments) and from the XFEL (e.g. adaptation to the available data acquisition system). The status and future perspective of the development including automatic laser alignment systems will be reported in the presentation. We will discuss the most promising and important new physics experiments that will be enabled by the combination of PW-class lasers and the world-class FEL's x-ray beam.

Motorized control for mirror mount apparatus

DOEpatents

Cutburth, Ronald W.

1989-01-01

A motorized control and automatic braking system for adjusting mirror mount apparatus is disclosed. The motor control includes a planetary gear arrangement to provide improved pitch adjustment capability while permitting a small packaged design. The motor control for mirror mount adjustment is suitable for laser beam propagation applications. The brake is a system of constant contact, floating detents which engage the planetary gear at selected between-teeth increments to stop rotation instantaneously when the drive motor stops.

Integration of Point Clouds from Terrestrial Laser Scanning and Image-Based Matching for Generating High-Resolution Orthoimages

NASA Astrophysics Data System (ADS)

Salach, A.; Markiewicza, J. S.; Zawieska, D.

2016-06-01

An orthoimage is one of the basic photogrammetric products used for architectural documentation of historical objects; recently, it has become a standard in such work. Considering the increasing popularity of photogrammetric techniques applied in the cultural heritage domain, this research examines the two most popular measuring technologies: terrestrial laser scanning, and automatic processing of digital photographs. The basic objective of the performed works presented in this paper was to optimize the quality of generated high-resolution orthoimages using integration of data acquired by a Z+F 5006 terrestrial laser scanner and a Canon EOS 5D Mark II digital camera. The subject was one of the walls of the "Blue Chamber" of the Museum of King Jan III's Palace at Wilanów (Warsaw, Poland). The high-resolution images resulting from integration of the point clouds acquired by the different methods were analysed in detail with respect to geometric and radiometric correctness.

Automated polarization control for the precise alignment of laser-induced self-organized nanostructures

NASA Astrophysics Data System (ADS)

Hermens, Ulrike; Pothen, Mario; Winands, Kai; Arntz, Kristian; Klocke, Fritz

2018-02-01

Laser-induced periodic surface structures (LIPSS) found in particular applications in the fields of surface functionalization have been investigated since many years. The direction of these ripple structures with a periodicity in the nanoscale can be manipulated by changing the laser polarization. For industrial use, it is useful to manipulate the direction of these structures automatically and to obtain smooth changes of their orientation without any visible inhomogeneity. However, currently no system solution exists that is able to control the polarization direction completely automated in one software solution so far. In this paper, a system solution is presented that includes a liquid crystal polarizer to control the polarization direction. It is synchronized with a scanner, a dynamic beam expander and a five axis-system. It provides fast switching times and small step sizes. First results of fabricated structures are also presented. In a systematic study, the conjunction of LIPSS with different orientation in two parallel line scans has been investigated.

Experimental investigation on densification behavior and surface roughness of AlSi10Mg powders produced by selective laser melting

NASA Astrophysics Data System (ADS)

Wang, Lin-zhi; Wang, Sen; Wu, Jiao-jiao

2017-11-01

Effects of laser energy density (LED) on densities and surface roughness of AlSi10Mg samples processed by selective laser melting were studied. The densification behaviors of the SLM manufactured AlSi10Mg samples at different LEDs were characterized by a solid densitometer, an industrial X-ray and CT detection system. A field emission scanning electron microscope, an automatic optical measuring system, and a surface profiler were used for measurements of surface roughness. The results show that relatively high density can be obtained with the point distance of 80-105 μm and the exposure time of 140-160 μs. The LED has an important influence on the surface morphology of the forming part, too high LED may lead to balling effect, while too low LED tends to produce defects, such as porosity and microcrack, and then affect surface roughness and porosities of the parts finally.

Automatic Tracking Algorithm in Coaxial Near-Infrared Laser Ablation Endoscope for Fetus Surgery

NASA Astrophysics Data System (ADS)

Hu, Yan; Yamanaka, Noriaki; Masamune, Ken

2014-07-01

This article reports a stable vessel object tracking method for the treatment of twin-to-twin transfusion syndrome based on our previous 2 DOF endoscope. During the treatment of laser coagulation, it is necessary to focus on the exact position of the target object, however it moves by the mother's respiratory motion and still remains a challenge to obtain and track the position precisely. In this article, an algorithm which uses features from accelerated segment test (FAST) to extract the features and optical flow as the object tracking method, is proposed to deal with above problem. Further, we experimentally simulate the movement due to the mother's respiration, and the results of position errors and similarity verify the effectiveness of the proposed tracking algorithm for laser ablation endoscopy in-vitro and under water considering two influential factors. At average, the errors are about 10 pixels and the similarity over 0.92 are obtained in the experiments.

A time domain simulation of a beam control system

NASA Astrophysics Data System (ADS)

Mitchell, J. R.

1981-02-01

The Airborne Laser Laboratory (ALL) is being developed by the Air Force to investigate the integration and operation of high energy laser components in a dynamic airborne environment and to study the propagation of laser light from an airborne vehicle to an airborne target. The ALL is composed of several systems; among these are the Airborne Pointing and Tracking System (APT) and the Automatic Alignment System (AAS). This report presents the results of performing a time domain dynamic simulation for an integrated beam control system composed of the APT and AAS. The simulation is performed on a digital computer using the MIMIC language. It includes models of the dynamics of the system and of disturbances. Also presented in the report are the rationales and developments of these models. The data from the simulation code is summarized by several plots. In addition results from massaging the data with waveform analysis packages are presented. The results are discussed and conclusions are drawn.

[Research on direct forming of comminuted fracture surgery orienting model by selective laser melting].

PubMed

He, Xingrong; Yang, Yongqiang; Wu, Weihui; Wang, Di; Ding, Huanwen; Huang, Weihong

2010-06-01

In order to simplify the distal femoral comminuted fracture surgery and improve the accuracy of the parts to be reset, a kind of surgery orienting model for the surgery operation was designed according to the scanning data of computer tomography and the three-dimensional reconstruction image. With the use of DiMetal-280 selective laser melting rapid prototyping system, the surgery orienting model of 316L stainless steel was made through orthogonal experiment for processing parameter optimization. The technology of direct manufacturing of surgery orienting model by selective laser melting was noted to have obvious superiority with high speed, precise profile and good accuracy in size when compared with the conventional one. The model was applied in a real surgical operation for thighbone replacement; it worked well. The successful development of the model provides a new method for the automatic manufacture of customized surgery model, thus building a foundation for more clinical applications in the future.

A fast data acquisition system for the study of transient events by high repetition rate time-of-flight mass spectrometry

NASA Technical Reports Server (NTRS)

Lincoln, K. A.; Bechtel, R. D.

1986-01-01

Recent advances in commercially available data acquisition electronics embodying high speed A/D conversion coupled to increased memory storage have now made practical (at least within time intervals of a third of a millisecond or more) the capturing of all of the data generated by a high repetition rate time-of-flight mass spectrometer producing complete spectra every 25 to 35 microseconds. Such a system was assembled and interfaced with a personal computer for control and management of data. The applications are described for recording time-resolved spectra of individual vapor plumes induced from the pulsed-laser heating of material. Each laser pulse triggers the system to generate automatically a 3-dimensional (3-D) presentation of the time-resolved spectra with m/z labeling of the major mass peaks, plus an intensity versus time display of both the laser pulse and the resulting vapor pulse. The software also permits storing of data and its presentation in various additional forms.

High-flexibility combinatorial peptide synthesis with laser-based transfer of monomers in solid matrix material.

PubMed

Loeffler, Felix F; Foertsch, Tobias C; Popov, Roman; Mattes, Daniela S; Schlageter, Martin; Sedlmayr, Martyna; Ridder, Barbara; Dang, Florian-Xuan; von Bojničić-Kninski, Clemens; Weber, Laura K; Fischer, Andrea; Greifenstein, Juliane; Bykovskaya, Valentina; Buliev, Ivan; Bischoff, F Ralf; Hahn, Lothar; Meier, Michael A R; Bräse, Stefan; Powell, Annie K; Balaban, Teodor Silviu; Breitling, Frank; Nesterov-Mueller, Alexander

2016-06-14

Laser writing is used to structure surfaces in many different ways in materials and life sciences. However, combinatorial patterning applications are still limited. Here we present a method for cost-efficient combinatorial synthesis of very-high-density peptide arrays with natural and synthetic monomers. A laser automatically transfers nanometre-thin solid material spots from different donor slides to an acceptor. Each donor bears a thin polymer film, embedding one type of monomer. Coupling occurs in a separate heating step, where the matrix becomes viscous and building blocks diffuse and couple to the acceptor surface. Furthermore, we can consecutively deposit two material layers of activation reagents and amino acids. Subsequent heat-induced mixing facilitates an in situ activation and coupling of the monomers. This allows us to incorporate building blocks with click chemistry compatibility or a large variety of commercially available non-activated, for example, posttranslationally modified building blocks into the array's peptides with >17,000 spots per cm(2).

Single-trial laser-evoked potentials feature extraction for prediction of pain perception.

PubMed

Huang, Gan; Xiao, Ping; Hu, Li; Hung, Yeung Sam; Zhang, Zhiguo

2013-01-01

Pain is a highly subjective experience, and the availability of an objective assessment of pain perception would be of great importance for both basic and clinical applications. The objective of the present study is to develop a novel approach to extract pain-related features from single-trial laser-evoked potentials (LEPs) for classification of pain perception. The single-trial LEP feature extraction approach combines a spatial filtering using common spatial pattern (CSP) and a multiple linear regression (MLR). The CSP method is effective in separating laser-evoked EEG response from ongoing EEG activity, while MLR is capable of automatically estimating the amplitudes and latencies of N2 and P2 from single-trial LEP waveforms. The extracted single-trial LEP features are used in a Naïve Bayes classifier to classify different levels of pain perceived by the subjects. The experimental results show that the proposed single-trial LEP feature extraction approach can effectively extract pain-related LEP features for achieving high classification accuracy.

A CityGML extension for traffic-sign objects that guides the automatic processing of data collected using Mobile Mapping technology

NASA Astrophysics Data System (ADS)

Varela-González, M.; Riveiro, B.; Arias-Sánchez, P.; González-Jorge, H.; Martínez-Sánchez, J.

2014-11-01

The rapid evolution of integral schemes, accounting for geometric and semantic data, has been importantly motivated by the advances in the last decade in mobile laser scanning technology; automation in data processing has also recently influenced the expansion of the new model concepts. This paper reviews some important issues involved in the new paradigms of city 3D modelling: an interoperable schema for city 3D modelling (cityGML) and mobile mapping technology to provide the features that composing the city model. This paper focuses in traffic signs, discussing their characterization using cityGML in order to ease the implementation of LiDAR technology in road management software, as well as analysing some limitations of the current technology in the labour of automatic detection and classification.

Laser cutting: industrial relevance, process optimization, and laser safety

NASA Astrophysics Data System (ADS)

Haferkamp, Heinz; Goede, Martin; von Busse, Alexander; Thuerk, Oliver

1998-09-01

Compared to other technological relevant laser machining processes, up to now laser cutting is the application most frequently used. With respect to the large amount of possible fields of application and the variety of different materials that can be machined, this technology has reached a stable position within the world market of material processing. Reachable machining quality for laser beam cutting is influenced by various laser and process parameters. Process integrated quality techniques have to be applied to ensure high-quality products and a cost effective use of the laser manufacturing plant. Therefore, rugged and versatile online process monitoring techniques at an affordable price would be desirable. Methods for the characterization of single plant components (e.g. laser source and optical path) have to be substituted by an omnivalent control system, capable of process data acquisition and analysis as well as the automatic adaptation of machining and laser parameters to changes in process and ambient conditions. At the Laser Zentrum Hannover eV, locally highly resolved thermographic measurements of the temperature distribution within the processing zone using cost effective measuring devices are performed. Characteristic values for cutting quality and plunge control as well as for the optimization of the surface roughness at the cutting edges can be deducted from the spatial distribution of the temperature field and the measured temperature gradients. Main influencing parameters on the temperature characteristic within the cutting zone are the laser beam intensity and pulse duration in pulse operation mode. For continuous operation mode, the temperature distribution is mainly determined by the laser output power related to the cutting velocity. With higher cutting velocities temperatures at the cutting front increase, reaching their maximum at the optimum cutting velocity. Here absorption of the incident laser radiation is drastically increased due to the angle between the normal of the cutting front and the laser beam axis. Beneath process optimization and control further work is focused on the characterization of particulate and gaseous laser generated air contaminants and adequate safety precautions like exhaust and filter systems.

Small molecule LX2343 ameliorates cognitive deficits in AD model mice by targeting both amyloid β production and clearance.

PubMed

Guo, Xiao-Dan; Sun, Guang-Long; Zhou, Ting-Ting; Xu, Xin; Zhu, Zhi-Yuan; Rukachaisirikul, Vatcharin; Hu, Li-Hong; Shen, Xu

2016-09-01

Streptozotocin (STZ) is widely used to induce oxidative damage and to impair glucose metabolism, apoptosis, and tau/Aβ pathology, eventually leading to cognitive deficits in both in vitro and in vivo models of Alzheimer's disease (AD). In this study, we constructed a cell-based platform using STZ to induce stress conditions mimicking the complicated pathologies of AD in vitro, and evaluated the anti-amyloid effects of a small molecule, N-(1,3-benzodioxol-5-yl)-2-[5-chloro-2-methoxy(phenylsulfonyl)anilino]acetamide (LX2343) in the amelioration of cognitive deficits in AD model mice. Cell-based assays for screening anti-amyloid compounds were established by assessing Aβ accumulation in HEK293-APP sw and CHO-APP cells, and Aβ clearance in primary astrocytes and SH-SY5Y cells after the cells were treated with STZ in the presence of the test compounds. Autophagic flux was observed using confocal laser scanning microscopy. APP/PS1 transgenic mice were administered LX2343 (10 mg·kg -1 ·d -1 , ip) for 100 d. After LX2343 administration, cognitive ability of the mice was evaluated using Morris water maze test, and senile plaques in the brains were detected using Thioflavine S staining. ELISA assay was used to evaluate Aβ and sAPPβ levels, while Western blot analysis was used to measure the signaling proteins in both cell and animal brains. LX2343 (5-20 μmol/L) dose-dependently decreased Aβ accumulation in HEK293-APP sw and CHO-APP cells, and promoted Aβ clearance in SH-SY5Y cells and primary astrocytes. The anti-amyloid effects of LX2343 were attributed to suppressing JNK-mediated APP Thr668 phosphorylation, thus inhibiting APP cleavage on one hand, and inhibiting BACE1 enzymatic activity with an IC 50 value of 11.43±0.36 μmol/L, on the other hand. Furthermore, LX2343 acted as a non-ATP competitive PI3K inhibitor to negatively regulate AKT/mTOR signaling, thus promoting autophagy, and increasing Aβ clearance. Administration of LX2343 in APP/PS1 transgenic mice significantly ameliorated cognitive deficits and markedly ameliorated the Aβ pathology in their brains. LX2343 ameliorates cognitive dysfunction in APP/PS1 transgenic mice via both Aβ production inhibition and clearance promotion, which highlights the potential of LX2343 in the treatment of AD.

Determination of glomerular function in advanced renal failure.

PubMed Central

Manz, F; Alatas, H; Kochen, W; Lutz, P; Rebien, W; Schärer, K

1977-01-01

In 15 children with advanced chronic renal failure, glomerular filtration rate was determined by different methods. Inulin clearance correlated well with the mean of creatinine and urea clearance, and also with 51-chromium edetic acid (EDTA) clearance measured over 24 hours. The absolute values of creatinine clearance and of 51Cr-EDTA clearance measured up to 8 hours were higher than inulin clearance. In advanced renal failure both the 51Cr-EDTA clearance measured over 24 hours, and the mean of creatinine and urea clearance, provide acceptable estimates of true glomerular filtration rate. PMID:411426

Benefits And Humanisation Of The Working Environment By Using Laser Inspection Systems In The Industry

NASA Astrophysics Data System (ADS)

Mueller, Peter; Pietzsch, Karl; Feige, Christian

1989-02-01

At a time of rapid development, introduction of new technologies, and increasing world-wide competition, the quality specifications for products and materials becoming even more demanding. This also applies with regard to the avoidance of defects in the surfaces of materials. Consequently there is a need for systems which allow 100% in-line testing of materials and surfaces during the production of, e.g. textiles, data storage media, papers, films and metals. Thanks to its optical and electronical precision, its unlimited applications - even under the most severe conditions-and its absolutely constant acuity, compared with visual inspection, the Sick-Scan-System is an excellent means for improving quality and profits in industrial manufacture, reducing rejects production and thus providing even more customer satisfaction. Here we describe briefly our laser scanner technology. It will set new standards in the area of automatic inspection, and the term laser tested will stablish itself as a mark of quality. In the last few years laser scanning inspection systems have been further developed in collaboration with a large number of materials manufacturers. These systems have been adopted in modern production lines and demonstrate their economy.

Self-calibration method for rotating laser positioning system using interscanning technology and ultrasonic ranging.

PubMed

Wu, Jun; Yu, Zhijing; Zhuge, Jingchang

2016-04-01

A rotating laser positioning system (RLPS) is an efficient measurement method for large-scale metrology. Due to multiple transmitter stations, which consist of a measurement network, the position relationship of these stations must be first calibrated. However, with such auxiliary devices such as a laser tracker, scale bar, and complex calibration process, the traditional calibration methods greatly reduce the measurement efficiency. This paper proposes a self-calibration method for RLPS, which can automatically obtain the position relationship. The method is implemented through interscanning technology by using a calibration bar mounted on the transmitter station. Each bar is composed of three RLPS receivers and one ultrasonic sensor whose coordinates are known in advance. The calibration algorithm is mainly based on multiplane and distance constraints and is introduced in detail through a two-station mathematical model. The repeated experiments demonstrate that the coordinate measurement uncertainty of spatial points by using this method is about 0.1 mm, and the accuracy experiments show that the average coordinate measurement deviation is about 0.3 mm compared with a laser tracker. The accuracy can meet the requirements of most applications, while the calibration efficiency is significantly improved.

Novel micro-Raman setup with tunable laser excitation for time-efficient resonance Raman microscopy and imaging.

PubMed

Stürzl, Ninette; Lebedkin, Sergei; Klumpp, Stefanie; Hennrich, Frank; Kappes, Manfred M

2013-05-07

We describe a micro-Raman setup allowing for efficient resonance Raman spectroscopy (RRS), i.e., mapping of Raman spectra as a function of tunable laser excitation wavelength. The instrument employs angle-tunable bandpass optical filters which are integrated into software-controlled Raman and laser cleanup filter devices. These automatically follow the excitation laser wavelength and combine tunability with high bandpass transmission as well as high off-band blocking of light. Whereas the spectral intervals which can be simultaneously acquired are bandpass limited to ~350 cm(-1), they can be tuned across the spectrum of interest to access all characteristic Raman features. As an illustration of performance, we present Raman mapping of single-walled carbon nanotubes (SWNTs): (i) in a small volume of water-surfactant dispersion as well as (ii) after deposition onto a substrate. A significant improvement in the acquisition time (and efficiency) is demonstrated compared to previous RRS implementations. These results may help to establish (micro) Raman spectral mapping as a routine tool for characterization of SWNTs as well as other materials with a pronounced resonance Raman response in the visible-near-infrared spectral region.

Optically stabilized Erbium fiber frequency comb with hybrid mode-locking and a broad tunable range of repetition rate.

PubMed

Yang, Honglei; Wu, Xuejian; Zhang, Hongyuan; Zhao, Shijie; Yang, Lijun; Wei, Haoyun; Li, Yan

2016-12-01

We present an optically stabilized Erbium fiber frequency comb with a broad repetition rate tuning range based on a hybrid mode-locked oscillator. We lock two comb modes to narrow-linewidth reference lasers in turn to investigate the best performance of control loops. The control bandwidth of fast and slow piezoelectric transducers reaches 70 kHz, while that of pump current modulation with phase-lead compensation is extended to 32 kHz, exceeding laser intrinsic response. Eventually, simultaneous lock of both loops is realized to totally phase-stabilize the comb, which will facilitate precision dual-comb spectroscopy, laser ranging, and timing distribution. In addition, a 1.8-MHz span of the repetition rate is achieved by an automatic optical delay line that is helpful in manufacturing a secondary comb with a similar repetition rate. The oscillator is housed in a homemade temperature-controlled box with an accuracy of ±0.02  K, which not only keeps high signal-to-noise ratio of the beat notes with reference lasers, but also guarantees self-starting at the same mode-locking every time.

Automated motile cell capture and analysis with optical traps.

PubMed

Shao, Bing; Nascimento, Jaclyn M; Shi, Linda Z; Botvinick, Elliot L

2007-01-01

Laser trapping in the near infrared regime is a noninvasive and microfluidic-compatible biomedical tool. This chapter examines the use of optical trapping as a quantitative measure of sperm motility. The single point gradient trap is used to directly measure the swimming forces of sperm from several different species. These forces could provide useful information about the overall sperm motility and semen quality. The swimming force is measured by trapping sperm and subsequently decreasing laser power until the sperm is capable of escaping the trap. Swimming trajectories were calculated by custom built software, an automatic sperm tracking algorithm called the single sperm tracking algorithm or SSTA. A real-time automated tracking and trapping system, or RATTS, which operates at video rate, was developed to perform experiments with minimal human involvement. After the experimenter initially identifies and clicks the computer mouse on the sperm-of-interest, RATTS performs all further tracking and trapping functions without human intervention. Additionally, an annular laser trap which is potentially useful for high-throughput sperm sorting based on motility and chemotaxis was developed. This low power trap offers a more gentle way for studying the effects of laser radiation, optical force, and external obstacles on sperm swimming pattern.

Handheld laser scanner automatic registration based on random coding

NASA Astrophysics Data System (ADS)

He, Lei; Yu, Chun-ping; Wang, Li

2011-06-01

Current research on Laser Scanner often focuses mainly on the static measurement. Little use has been made of dynamic measurement, that are appropriate for more problems and situations. In particular, traditional Laser Scanner must Keep stable to scan and measure coordinate transformation parameters between different station. In order to make the scanning measurement intelligently and rapidly, in this paper ,we developed a new registration algorithm for handleheld laser scanner based on the positon of target, which realize the dynamic measurement of handheld laser scanner without any more complex work. the double camera on laser scanner can take photograph of the artificial target points to get the three-dimensional coordinates, this points is designed by random coding. And then, a set of matched points is found from control points to realize the orientation of scanner by the least-square common points transformation. After that the double camera can directly measure the laser point cloud in the surface of object and get the point cloud data in an unified coordinate system. There are three major contributions in the paper. Firstly, a laser scanner based on binocular vision is designed with double camera and one laser head. By those, the real-time orientation of laser scanner is realized and the efficiency is improved. Secondly, the coding marker is introduced to solve the data matching, a random coding method is proposed. Compared with other coding methods,the marker with this method is simple to match and can avoid the shading for the object. Finally, a recognition method of coding maker is proposed, with the use of the distance recognition, it is more efficient. The method present here can be used widely in any measurement from small to huge obiect, such as vehicle, airplane which strengthen its intelligence and efficiency. The results of experiments and theory analzing demonstrate that proposed method could realize the dynamic measurement of handheld laser scanner. Theory analysis and experiment shows the method is reasonable and efficient.

Automatic system for 3D reconstruction of the chick eye based on digital photographs.

PubMed

Wong, Alexander; Genest, Reno; Chandrashekar, Naveen; Choh, Vivian; Irving, Elizabeth L

2012-01-01

The geometry of anatomical specimens is very complex and accurate 3D reconstruction is important for morphological studies, finite element analysis (FEA) and rapid prototyping. Although magnetic resonance imaging, computed tomography and laser scanners can be used for reconstructing biological structures, the cost of the equipment is fairly high and specialised technicians are required to operate the equipment, making such approaches limiting in terms of accessibility. In this paper, a novel automatic system for 3D surface reconstruction of the chick eye from digital photographs of a serially sectioned specimen is presented as a potential cost-effective and practical alternative. The system is designed to allow for automatic detection of the external surface of the chick eye. Automatic alignment of the photographs is performed using a combination of coloured markers and an algorithm based on complex phase order likelihood that is robust to noise and illumination variations. Automatic segmentation of the external boundaries of the eye from the aligned photographs is performed using a novel level-set segmentation approach based on a complex phase order energy functional. The extracted boundaries are sampled to construct a 3D point cloud, and a combination of Delaunay triangulation and subdivision surfaces is employed to construct the final triangular mesh. Experimental results using digital photographs of the chick eye show that the proposed system is capable of producing accurate 3D reconstructions of the external surface of the eye. The 3D model geometry is similar to a real chick eye and could be used for morphological studies and FEA.

Temperature effect on laser-induced breakdown spectroscopy spectra of molten and solid salts

NASA Astrophysics Data System (ADS)

Hanson, Cynthia; Phongikaroon, Supathorn; Scott, Jill R.

2014-07-01

Laser-induced breakdown spectroscopy (LIBS) has been investigated as a potential analytical tool to improve operations and safeguards for electrorefiners, such as those used in processing spent nuclear fuel. This study set out to better understand the effect of sample temperature and physical state on LIBS spectra of molten and solid salts by building calibration curves of cerium and assessing self-absorption, plasma temperature, electron density, and local thermal equilibrium (LTE). Samples were composed of a LiCl-KCl eutectic salt, an internal standard of MnCl2, and varying concentrations of CeCl3 (0.1, 0.3, 0.5, 0.8, and 1.0 wt.% Ce) under different temperatures (773, 723, 673, 623, and 573 K). Analysis of salts in their molten form is preferred as plasma plumes from molten samples experienced less self-absorption, less variability in plasma temperature, and higher clearance of the minimum electron density required for local thermal equilibrium. These differences are attributed to plasma dynamics as a result of phase changes. Spectral reproducibility was also better in the molten state due to sample homogeneity.

Head flying characteristics in heat assisted magnetic recording considering various nanoscale heat transfer models

NASA Astrophysics Data System (ADS)

Hu, Yueqiang; Wu, Haoyu; Meng, Yonggang; Wang, Yu; Bogy, David

2018-01-01

The thermal issues in heat-assisted magnetic recording (HAMR) technology have drawn much attention in the recent literature. In this paper, the head flying characteristics and thermal performance of a HAMR system during the touch-down process considering different nanoscale heat transfer models across the head-disk interface are numerically studied. An optical-thermal-mechanical coupled model is first described. The coupling efficiency of the near field transducer is found to be dependent on the head disk clearance. The shortcomings of a constant disk-temperature model are investigated, which reveals the importance of considering the disk temperature as a variable. A study of the head flying on the disk is carried out using an air conduction model and additional near-field heat transfer models. It is shown that when the head disk interface is filled with a solid material caused by the laser-induced accumulation, the heat transfer coefficient can become unexpectedly large and the head's temperature can rise beyond desirable levels. Finally, the additional head protrusion due to the laser heating is investigated.

Automatic Detection of Electric Power Troubles (ADEPT)

NASA Technical Reports Server (NTRS)

Wang, Caroline; Zeanah, Hugh; Anderson, Audie; Patrick, Clint; Brady, Mike; Ford, Donnie

1988-01-01

Automatic Detection of Electric Power Troubles (A DEPT) is an expert system that integrates knowledge from three different suppliers to offer an advanced fault-detection system. It is designed for two modes of operation: real time fault isolation and simulated modeling. Real time fault isolation of components is accomplished on a power system breadboard through the Fault Isolation Expert System (FIES II) interface with a rule system developed in-house. Faults are quickly detected and displayed and the rules and chain of reasoning optionally provided on a laser printer. This system consists of a simulated space station power module using direct-current power supplies for solar arrays on three power buses. For tests of the system's ablilty to locate faults inserted via switches, loads are configured by an INTEL microcomputer and the Symbolics artificial intelligence development system. As these loads are resistive in nature, Ohm's Law is used as the basis for rules by which faults are located. The three-bus system can correct faults automatically where there is a surplus of power available on any of the three buses. Techniques developed and used can be applied readily to other control systems requiring rapid intelligent decisions. Simulated modeling, used for theoretical studies, is implemented using a modified version of Kennedy Space Center's KATE (Knowledge-Based Automatic Test Equipment), FIES II windowing, and an ADEPT knowledge base.

Automatic Detection of Electric Power Troubles (ADEPT)

NASA Astrophysics Data System (ADS)

Wang, Caroline; Zeanah, Hugh; Anderson, Audie; Patrick, Clint; Brady, Mike; Ford, Donnie

1988-11-01

Automatic Detection of Electric Power Troubles (A DEPT) is an expert system that integrates knowledge from three different suppliers to offer an advanced fault-detection system. It is designed for two modes of operation: real time fault isolation and simulated modeling. Real time fault isolation of components is accomplished on a power system breadboard through the Fault Isolation Expert System (FIES II) interface with a rule system developed in-house. Faults are quickly detected and displayed and the rules and chain of reasoning optionally provided on a laser printer. This system consists of a simulated space station power module using direct-current power supplies for solar arrays on three power buses. For tests of the system's ablilty to locate faults inserted via switches, loads are configured by an INTEL microcomputer and the Symbolics artificial intelligence development system. As these loads are resistive in nature, Ohm's Law is used as the basis for rules by which faults are located. The three-bus system can correct faults automatically where there is a surplus of power available on any of the three buses. Techniques developed and used can be applied readily to other control systems requiring rapid intelligent decisions. Simulated modeling, used for theoretical studies, is implemented using a modified version of Kennedy Space Center's KATE (Knowledge-Based Automatic Test Equipment), FIES II windowing, and an ADEPT knowledge base.

The efficacy of fractional carbon dioxide (CO2) laser combined with terbinafine hydrochloride 1% cream for the treatment of onychomycosis.

PubMed

Shi, Jian; Li, Jin; Huang, He; Permatasari, Felicia; Liu, Juan; Xu, Yang; Wu, Di; Zhou, Bing-Rong; Luo, Dan

2017-10-01

Although systemic and topical antifungal agents are widely used to treat onychomycosis, oral medications can cause adverse effects and the efficacy of topical agents is not satisfying. Currently, laser treatment has been studied for its efficacy in the treatment of onychomycosis. Our study was aimed to evaluate the efficacy of fractional carbon dioxide (CO 2 ) laser treatment combined with terbinafine cream for 6 months in the treatment of onychomycosis and to analyze the influencing factors. A total of 30 participants (124 nails) with clinical and mycological diagnosis of onychomycosis received fractional CO 2 laser treatment at 2-week interval combined with terbinafine cream once daily for 6 months. The clinical efficacy rate (CER) was assessed from the percentage of fully normal-appearing nails or nails with ≤5% abnormal appearance, and the mycological clearance rate (MCR) was assessed from the percentage of nails with negative fungal microscopy. The CER was evaluated at 3 time points: at the end of treatment (58.9%), at 1 month after the last treatment (63.5%), and at 3 months after the last treatment (68.5%). The MCRs at 1 month and 3 months after the last treatment were 77.4 and 74.2%, respectively. The evaluation of influencing factors showed significantly higher CER (p < 0.05) in nails of participants with age <50 years, distal lateral subungual onychomycosis (DLSO), superficial white onychomycosis (SWO), nail thickness <2 mm, affected first-to-fourth finger/toenails, Trichophyton rubrum, and Trichophyton mentagrophytes. All participants experienced tolerable mild burning sensation during laser treatment, but there were no other adverse reactions reported. Fractional CO 2 laser treatment combined with terbinafine cream for 6 months was an effective and safe method for the treatment of onychomycosis. There were 5 factors that positively influenced the treatment outcome: age, clinical type of onychomycosis, nail thickness, involved nail, and species of fungus.

Indoor space 3D visual reconstruction using mobile cart with laser scanner and cameras

NASA Astrophysics Data System (ADS)

Gashongore, Prince Dukundane; Kawasue, Kikuhito; Yoshida, Kumiko; Aoki, Ryota

2017-02-01

Indoor space 3D visual reconstruction has many applications and, once done accurately, it enables people to conduct different indoor activities in an efficient manner. For example, an effective and efficient emergency rescue response can be accomplished in a fire disaster situation by using 3D visual information of a destroyed building. Therefore, an accurate Indoor Space 3D visual reconstruction system which can be operated in any given environment without GPS has been developed using a Human-Operated mobile cart equipped with a laser scanner, CCD camera, omnidirectional camera and a computer. By using the system, accurate indoor 3D Visual Data is reconstructed automatically. The obtained 3D data can be used for rescue operations, guiding blind or partially sighted persons and so forth.

Method of recognizing the high-speed railway noise barriers based on the distance image

NASA Astrophysics Data System (ADS)

Ma, Le; Shao, Shuangyun; Feng, Qibo; Liu, Bingqian; Kim, Chol Ryong

2016-10-01

The damage or lack of the noise barriers is one of the important hidden troubles endangering the safety of high-speed railway. In order to obtain the vibration information of the noise barriers, the online detection systems based on laser vision were proposed. The systems capture images of the laser stripe on the noise barriers and export data files containing distance information between the detection systems on the train and the noise barriers. The vibration status or damage of the noise barriers can be estimated depending on the distance information. In this paper, we focused on the method of separating the area of noise barrier from the background automatically. The test results showed that the proposed method is in good efficiency and accuracy.

Effect of Internal Clearance on Load Distribution and Life of Radially Loaded Ball and Roller Bearings

NASA Technical Reports Server (NTRS)

Oswald, Fred B.; Zaretsky, Erwin V.; Poplawski, Joseph V.

2012-01-01

The effect of internal clearance on radially loaded deepgroove ball and cylindrical roller bearing load distribution and fatigue life was determined for four clearance groups defined in the bearing standards. The analysis was extended to negative clearance (interference) conditions to produce a curve of life factor versus internal clearance. Rolling-element loads can be optimized and bearing life maximized for a small negative operating clearance. Life declines gradually with positive clearance and rapidly with increasing negative clearance. Relationships were found between bearing life and internal clearance as a function of ball or roller diameter, adjusted for load. Results are presented as life factors for radially loaded bearings independent of bearing size or applied load. In addition, a modified Stribeck Equation is presented that relates the maximum rolling-element load to internal bearing clearance.

The modern trends of the evolution laser information technology in oncology

NASA Astrophysics Data System (ADS)

Mikov, A. A.; Svirin, V. N.

2008-04-01

Laser-optical information technologies and devices develop since the 70- years at the end of 20 century and are broadly used for diagnostics and treatment of oncological diseases to date. Although such methods as photodynamic therapy (PDT), laser-induce thermotherapy (LITT), fluorescent diagnostics and spectrophotometry already more than 30 years are used for treatment and diagnostics of oncological diseases, nevertheless, they are enough new methods and, as a rule, are used in large scientific centers and medical institutions. This is bound, first of all, with lack of information on modern method of cancer treatment, the absence of widely available laser procedures and corresponding devices in the polyclinics and even in district hospitals, as well as insufficient understanding of application areas, where laser methods has an advantage by comparison, for instance, with beam or chemotherapy. At present day laser methods are fast upcoming direction of the treatment oncological diseases. This is explained by progress in development essentially laser, particularly diode, improvement electronic and computing components and broad introduction software-algorithmic methods of control the undertaking therapeutic and diagnostic procedures. In article are considered new laser methods of the undertaking diagnostic and therapeutic procedures and is shown that introduction multiwave laser radiation for probe and influences on tissue, the different methods of the determination of the functional state of tissues, realization of the on-line diagnostics when carrying out the therapeutic procedures, automatic control systems of the power laser radiation, which depends on state patient tissue, as well as software-algorithmic methods of management session therapeutic and diagnostic procedures greatly raises efficiency of the treatment oncological diseases. On an example of the multipurpose laser therapeutic devices("MLTA") developed and introduced in clinical practice and multipurpose laser diagnostic complexes ("MLDC"), the realizing offered methods, are shown the basic tendencies of development laser methods in oncology, concrete technical decisions and the experimental clinical material showing increase of efficiency of treatment of a cancer at their realization are resulted. It is shown, that realization of the offered methods and technical technologies opens new competitive advantages laser technologies in comparison with beam and chemical-therapy at treatment of oncological diseases.

The application of image processing in the measurement for three-light-axis parallelity of laser ranger

NASA Astrophysics Data System (ADS)

Wang, Yang; Wang, Qianqian

2008-12-01

When laser ranger is transported or used in field operations, the transmitting axis, receiving axis and aiming axis may be not parallel. The nonparallelism of the three-light-axis will affect the range-measuring ability or make laser ranger not be operated exactly. So testing and adjusting the three-light-axis parallelity in the production and maintenance of laser ranger is important to ensure using laser ranger reliably. The paper proposes a new measurement method using digital image processing based on the comparison of some common measurement methods for the three-light-axis parallelity. It uses large aperture off-axis paraboloid reflector to get the images of laser spot and white light cross line, and then process the images on LabVIEW platform. The center of white light cross line can be achieved by the matching arithmetic in LABVIEW DLL. And the center of laser spot can be achieved by gradation transformation, binarization and area filter in turn. The software system can set CCD, detect the off-axis paraboloid reflector, measure the parallelity of transmitting axis and aiming axis and control the attenuation device. The hardware system selects SAA7111A, a programmable vedio decoding chip, to perform A/D conversion. FIFO (first-in first-out) is selected as buffer.USB bus is used to transmit data to PC. The three-light-axis parallelity can be achieved according to the position bias between them. The device based on this method has been already used. The application proves this method has high precision, speediness and automatization.

Comparing the accuracy of terrestrial laser scanner in measuring forest inventory variables to enhance better decision making for potential fire hazards

NASA Astrophysics Data System (ADS)

Ghimire, Suman; Xystrakis, Fotios; Koutsias, Nikos

2017-04-01

Forest inventory variables are essential in accessing the potential of wildfire hazard, obtaining above ground biomass and carbon sequestration which helps developing strategies for sustainable management of forests. Effective management of forest resources relies on the accuracy of such inventory variables. This study aims to compare the accuracy in obtaining the forest inventory variables like diameter at breast height (DBH) and tree height from Terrestrial Laser Scanner (Faro Focus 3D X 330) with that from the traditional forest inventory techniques in the Mediterranean forests of Greece. The data acquisition was carried out on an area of 9,539.8 m2 with six plots each of radius 6 m. Computree algorithm was applied for automatic detection of DBH from terrestrial laser scanner data. Similarly, tree height was estimated manually using CloudCompare software for the terrestrial laser scanner data. The field estimates of DBH and tree height was carried out using calipers and Nikon Forestry 550 Laser Rangefinder. The comparison of DBH measured between field estimates and Terrestrial Laser Scanner (TLS), resulted in R squared values ranging from 0.75 to 0.96 at the plot level. An average R2 and RMSE value of 0.80 and 1.07 m respectively was obtained when comparing the tree height between TLS and field data. Our results confirm that terrestrial laser scanner can provide nondestructive, high-resolution, and precise determination of forest inventory for better decision making in sustainable forest management and assessing potential of forest fire hazards.

Polymeric capsule-cushioned leukocyte cell membrane vesicles as a biomimetic delivery platform

NASA Astrophysics Data System (ADS)

Gao, Changyong; Wu, Zhiguang; Lin, Zhihua; Lin, Xiankun; He, Qiang

2016-02-01

We report a biomimetic delivery of microsized capsule-cushioned leukocyte membrane vesicles (CLMVs) through the conversion of freshly reassembled leukocyte membrane vesicles (LMVs), including membrane lipids and membrane-bound proteins onto the surface of layer-by-layer assembled polymeric multilayer microcapsules. The leukocyte membrane coating was verified by using electron microscopy, a quartz crystal microbalance, dynamic light scattering, and confocal laser scanning microscopy. The resulting CLMVs have the ability to effectively evade clearance by the immune system and thus prolong the circulation time in mice. Moreover, we also show that the right-side-out leukocyte membrane coating can distinctly improve the accumulation of capsules in tumor sites through the molecular recognition of membrane-bound proteins of CLMVs with those of tumor cells in vitro and in vivo. The natural cell membrane camouflaged polymeric multilayer capsules with the immunosuppressive and tumor-recognition functionalities of natural leukocytes provide a new biomimetic delivery platform for disease therapy.We report a biomimetic delivery of microsized capsule-cushioned leukocyte membrane vesicles (CLMVs) through the conversion of freshly reassembled leukocyte membrane vesicles (LMVs), including membrane lipids and membrane-bound proteins onto the surface of layer-by-layer assembled polymeric multilayer microcapsules. The leukocyte membrane coating was verified by using electron microscopy, a quartz crystal microbalance, dynamic light scattering, and confocal laser scanning microscopy. The resulting CLMVs have the ability to effectively evade clearance by the immune system and thus prolong the circulation time in mice. Moreover, we also show that the right-side-out leukocyte membrane coating can distinctly improve the accumulation of capsules in tumor sites through the molecular recognition of membrane-bound proteins of CLMVs with those of tumor cells in vitro and in vivo. The natural cell membrane camouflaged polymeric multilayer capsules with the immunosuppressive and tumor-recognition functionalities of natural leukocytes provide a new biomimetic delivery platform for disease therapy. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08407e

Laser range profiling for small target recognition

NASA Astrophysics Data System (ADS)

Steinvall, Ove; Tulldahl, Michael

2016-05-01

The detection and classification of small surface and airborne targets at long ranges is a growing need for naval security. Long range ID or ID at closer range of small targets has its limitations in imaging due to the demand on very high transverse sensor resolution. It is therefore motivated to look for 1D laser techniques for target ID. These include vibrometry, and laser range profiling. Vibrometry can give good results but is also sensitive to certain vibrating parts on the target being in the field of view. Laser range profiling is attractive because the maximum range can be substantial, especially for a small laser beam width. A range profiler can also be used in a scanning mode to detect targets within a certain sector. The same laser can also be used for active imaging when the target comes closer and is angular resolved. The present paper will show both experimental and simulated results for laser range profiling of small boats out to 6-7 km range and a UAV mockup at close range (1.3 km). We obtained good results with the profiling system both for target detection and recognition. Comparison of experimental and simulated range waveforms based on CAD models of the target support the idea of having a profiling system as a first recognition sensor and thus narrowing the search space for the automatic target recognition based on imaging at close ranges. The naval experiments took place in the Baltic Sea with many other active and passive EO sensors beside the profiling system. Discussion of data fusion between laser profiling and imaging systems will be given. The UAV experiments were made from the rooftop laboratory at FOI.

Performance scaling via passive pulse shaping in cavity-enhanced optical parametric chirped-pulse amplification.

PubMed

Siddiqui, Aleem M; Moses, Jeffrey; Hong, Kyung-Han; Lai, Chien-Jen; Kärtner, Franz X

2010-06-15

We show that an enhancement cavity seeded at the full repetition rate of the pump laser can automatically reshape small-signal gain across the interacting pulses in an optical parametric chirped-pulse amplifier for close-to-optimal operation, significantly increasing both the gain bandwidth and the conversion efficiency, in addition to boosting gain for high-repetition-rate amplification. Applied to a degenerate amplifier, the technique can provide an octave-spanning gain bandwidth.

Automatic extraction of pavement markings on streets from point cloud data of mobile LiDAR

NASA Astrophysics Data System (ADS)

Gao, Yang; Zhong, Ruofei; Tang, Tao; Wang, Liuzhao; Liu, Xianlin

2017-08-01

Pavement markings provide an important foundation as they help to keep roads users safe. Accurate and comprehensive information about pavement markings assists the road regulators and is useful in developing driverless technology. Mobile light detection and ranging (LiDAR) systems offer new opportunities to collect and process accurate pavement markings’ information. Mobile LiDAR systems can directly obtain the three-dimensional (3D) coordinates of an object, thus defining spatial data and the intensity of (3D) objects in a fast and efficient way. The RGB attribute information of data points can be obtained based on the panoramic camera in the system. In this paper, we present a novel method process to automatically extract pavement markings using multiple attribute information of the laser scanning point cloud from the mobile LiDAR data. This method process utilizes a differential grayscale of RGB color, laser pulse reflection intensity, and the differential intensity to identify and extract pavement markings. We utilized point cloud density to remove the noise and used morphological operations to eliminate the errors. In the application, we tested our method process on different sections of roads in Beijing, China, and Buffalo, NY, USA. The results indicated that both correctness (p) and completeness (r) were higher than 90%. The method process of this research can be applied to extract pavement markings from huge point cloud data produced by mobile LiDAR.

Volumetric vessel reconstruction method for absolute blood flow velocity measurement in Doppler OCT images

NASA Astrophysics Data System (ADS)

Qi, Li; Zhu, Jiang; Hancock, Aneeka M.; Dai, Cuixia; Zhang, Xuping; Frostig, Ron D.; Chen, Zhongping

2017-02-01

Doppler optical coherence tomography (DOCT) is considered one of the most promising functional imaging modalities for neuro biology research and has demonstrated the ability to quantify cerebral blood flow velocity at a high accuracy. However, the measurement of total absolute blood flow velocity (BFV) of major cerebral arteries is still a difficult problem since it not only relates to the properties of the laser and the scattering particles, but also relates to the geometry of both directions of the laser beam and the flow. In this paper, focusing on the analysis of cerebral hemodynamics, we presents a method to quantify the total absolute blood flow velocity in middle cerebral artery (MCA) based on volumetric vessel reconstruction from pure DOCT images. A modified region growing segmentation method is first used to localize the MCA on successive DOCT B-scan images. Vessel skeletonization, followed by an averaging gradient angle calculation method, is then carried out to obtain Doppler angles along the entire MCA. Once the Doppler angles are determined, the absolute blood flow velocity of each position on the MCA is easily found. Given a seed point position on the MCA, our approach could achieve automatic quantification of the fully distributed absolute BFV. Based on experiments conducted using a swept-source optical coherence tomography system, our approach could achieve automatic quantification of the fully distributed absolute BFV across different vessel branches in the rodent brain.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Fan; Wang, Yuanqing, E-mail: yqwang@nju.edu.cn; Li, Fenfang

The avalanche-photodiode-array (APD-array) laser detection and ranging (LADAR) system has been continually developed owing to its superiority of nonscanning, large field of view, high sensitivity, and high precision. However, how to achieve higher-efficient detection and better integration of the LADAR system for real-time three-dimensional (3D) imaging continues to be a problem. In this study, a novel LADAR system using four linear mode APDs (LmAPDs) is developed for high-efficient detection by adopting a modulation and multiplexing technique. Furthermore, an automatic control system for the array LADAR system is proposed and designed by applying the virtual instrumentation technique. The control system aimsmore » to achieve four functions: synchronization of laser emission and rotating platform, multi-channel synchronous data acquisition, real-time Ethernet upper monitoring, and real-time signal processing and 3D visualization. The structure and principle of the complete system are described in the paper. The experimental results demonstrate that the LADAR system is capable of achieving real-time 3D imaging on an omnidirectional rotating platform under the control of the virtual instrumentation system. The automatic imaging LADAR system utilized only 4 LmAPDs to achieve 256-pixel-per-frame detection with by employing 64-bit demodulator. Moreover, the lateral resolution is ∼15 cm and range accuracy is ∼4 cm root-mean-square error at a distance of ∼40 m.« less

Precise 3D Lug Pose Detection Sensor for Automatic Robot Welding Using a Structured-Light Vision System

PubMed Central

Park, Jae Byung; Lee, Seung Hun; Lee, Il Jae

2009-01-01

In this study, we propose a precise 3D lug pose detection sensor for automatic robot welding of a lug to a huge steel plate used in shipbuilding, where the lug is a handle to carry the huge steel plate. The proposed sensor consists of a camera and four laser line diodes, and its design parameters are determined by analyzing its detectable range and resolution. For the lug pose acquisition, four laser lines are projected on both lug and plate, and the projected lines are detected by the camera. For robust detection of the projected lines against the illumination change, the vertical threshold, thinning, Hough transform and separated Hough transform algorithms are successively applied to the camera image. The lug pose acquisition is carried out by two stages: the top view alignment and the side view alignment. The top view alignment is to detect the coarse lug pose relatively far from the lug, and the side view alignment is to detect the fine lug pose close to the lug. After the top view alignment, the robot is controlled to move close to the side of the lug for the side view alignment. By this way, the precise 3D lug pose can be obtained. Finally, experiments with the sensor prototype are carried out to verify the feasibility and effectiveness of the proposed sensor. PMID:22400007

Industrial applications of shearography for inspections of aircraft components

NASA Astrophysics Data System (ADS)

Krupka, Rene; Waltz, T.; Ettemeyer, Andreas

2003-05-01

Shearography has been validated as fast and reliable inspection technique for aerospace components. Following several years phase of evaluation of the technique, meanwhile, shearography has entered the industrial production inspection. The applications basically range from serial inspection in the production line to field inspection in assembly and to applications in the maintenance and repair area. In all applications, the main advantages of shearography, as very fast and full field inspection and high sensitivity even on very complex composite materials have led to the decision for laser shearography as inspection tool. In this paper, we present examples of recent industrial shearography inspection systems in the field of aerospace. One of the first industrial installations of laser shearography in Europe was a fully automatic inspection system for helicopter rotorblades. Complete rotor blades are inspected within 10 minutes on delaminations and debondings in the composite structure. In case of more complex components, robotic manipulation of the shearography camera has proven to be the optimum solution. An industry 6-axis robot gives utmost flexibility to position the camera in any angle and distance. Automatic defect marking systems have also been introduced to indicate the exact position of the defect directly on the inspected component. Other applications cover the inspection of abradable seals in jet engines and portable shearography inspection systems for maintenance and repair inspection in the field.