Stand-off laser Raman spectroscopy and its advancement in explosives detection

NASA Astrophysics Data System (ADS)

Liu, Sheng-run; Xue, Bin; Li, Yi-zhe; Wang, Hui

2017-10-01

The explosives detection has been a hot and difficult issue in the field of security it is particularly important to detect explosives quickly and reliably. There are many methods to detect explosives currently, stand-off Raman spectroscopy is one of the most promising and practical technologies, this technique can be used for non-contact and nondestructive detection, ensure the safety of attendants, at the same time the precision and speed of detection are also very high and be characterized by rapid response. This paper mainly gives an account of the fundamental principle of Raman spectroscopy, as well as recount major challenges of Standoff Laser Raman Spectroscopy applied in explosives detection and corresponding solutions. From the perspective of the system, this paper sums up related theories and techniques of the excitation laser and telescopic system etc.. Ultimately, a brief analysis and summary of the development trend of this technology is given.

Damage Detection in Rotorcraft Composite Structures Using Thermography and Laser-Based Ultrasound

NASA Technical Reports Server (NTRS)

Anastasi, Robert F.; Zalameda, Joseph N.; Madaras, Eric I.

2004-01-01

New rotorcraft structural composite designs incorporate lower structural weight, reduced manufacturing complexity, and improved threat protection. These new structural concepts require nondestructive evaluation inspection technologies that can potentially be field-portable and able to inspect complex geometries for damage or structural defects. Two candidate technologies were considered: Thermography and Laser-Based Ultrasound (Laser UT). Thermography and Laser UT have the advantage of being non-contact inspection methods, with Thermography being a full-field imaging method and Laser UT a point scanning technique. These techniques were used to inspect composite samples that contained both embedded flaws and impact damage of various size and shape. Results showed that the inspection techniques were able to detect both embedded and impact damage with varying degrees of success.

The application and research of the multi-receiving telescopes technology in laser ranging to space targets

NASA Astrophysics Data System (ADS)

Wu, Zhibo; Zhang, Haifeng; Zhang, Zhongping; Deng, Huarong; Li, Pu; Meng, Wendong; Cheng, Zhien; Shen, Lurun; Tang, Zhenhong

2014-11-01

Laser ranging technology can directly measure the distance between space targets and ground stations with the highest measurement precision and will play an irreplaceable role in orbit check and calibrating microwave measurement system. The precise orbit determination and accurate catalogue of space targets can also be realized by laser ranging with multi-stations. Among space targets, most of ones are inactive targets and space debris, which should be paid the great attentions for the safety of active spacecrafts. Because of laser diffuse reflection from the surface of targets, laser ranging to space debris has the characteristics of wide coverage and weak strength of laser echoes, even though the powerful laser system is applied. In order to increase the receiving ability of laser echoes, the large aperture telescope should be adopted. As well known, some disadvantages for one set of large aperture telescope, technical development difficulty and system running and maintenance complexity, will limit its flexible applications. The multi-receiving telescopes technology in laser ranging to space targets is put forward to realize the equivalent receiving ability produced by one larger aperture telescope by way of using multi-receiving telescopes, with the advantages of flexibility and maintenance. The theoretical analysis of the feasibility and key technologies of multi-receiving telescopes technology in laser ranging to space targets are presented in this paper. The experimental measurement system based on the 60cm SLR system and 1.56m astronomical telescopes with a distance of about 50m is established to provide the platform for researching on the multi-receiving telescopes technology. The laser ranging experiments to satellites equipped with retro-reflectors are successfully performed by using the above experimental system and verify the technical feasibility to increase the ability of echo detection. And the multi-receiving telescopes technology will become a novel effective way to improve the detection ability of laser ranging to space debris.

Navy/Marine Corps innovative science and technology developments for future enhanced mine detection capabilities

NASA Astrophysics Data System (ADS)

Holloway, John H., Jr.; Witherspoon, Ned H.; Miller, Richard E.; Davis, Kenn S.; Suiter, Harold R.; Hilton, Russell J.

2000-08-01

JMDT is a Navy/Marine Corps 6.2 Exploratory Development program that is closely coordinated with the 6.4 COBRA acquisition program. The objective of the program is to develop innovative science and technology to enhance future mine detection capabilities. The objective of the program is to develop innovative science and technology to enhance future mine detection capabilities. Prior to transition to acquisition, the COBRA ATD was extremely successful in demonstrating a passive airborne multispectral video sensor system operating in the tactical Pioneer unmanned aerial vehicle (UAV), combined with an integrated ground station subsystem to detect and locate minefields from surf zone to inland areas. JMDT is investigating advanced technology solutions for future enhancements in mine field detection capability beyond the current COBRA ATD demonstrated capabilities. JMDT has recently been delivered next- generation, innovative hardware which was specified by the Coastal System Station and developed under contract. This hardware includes an agile-tuning multispectral, polarimetric, digital video camera and advanced multi wavelength laser illumination technologies to extend the same sorts of multispectral detections from a UAV into the night and over shallow water and other difficult littoral regions. One of these illumination devices is an ultra- compact, highly-efficient near-IR laser diode array. The other is a multi-wavelength range-gateable laser. Additionally, in conjunction with this new technology, algorithm enhancements are being developed in JMDT for future naval capabilities which will outperform the already impressive record of automatic detection of minefields demonstrated by the COBAR ATD.

A novel Laser Ion Mobility Spectrometer

NASA Astrophysics Data System (ADS)

Göbel, J.; Kessler, M.; Langmeier, A.

2009-05-01

IMS is a well know technology within the range of security based applications. Its main advantages lie in the simplicity of measurement, along with a fast and sensitive detection method. Contemporary technology often fails due to interference substances, in conjunction with saturation effects and a low dynamic detection range. High throughput facilities, such as airports, require the analysis of many samples at low detection limits within a very short timeframe. High detection reliability is a requirement for safe and secure operation. In our present work we developed a laser based ion-mobility-sensor which shows several advantages over known IMS sensor technology. The goal of our research was to increase the sensitivity compared to the range of 63Ni based instruments. This was achieved with an optimised geometric drift tube design and a pulsed UV laser system at an efficient intensity. In this intensity range multi-photon ionisation is possible, which leads to higher selectivity in the ion-formation process itself. After high speed capturing of detection samples, a custom designed pattern recognition software toolbox provides reliable auto-detection capability with a learning algorithm and a graphical user interface.

Fractional CO2 Laser Resurfacing Complications

PubMed Central

Ramsdell, William M.

2012-01-01

Fractionated CO2 laser technology has allowed physicians to resurface patients with a lower rate of complications than nonfractionated ablative laser treatment. Unfortunately, adverse effects can still occur even with the best technology and physician care. Complication prevention, detection, and treatment are an important part of a physician's ability to provide the best result when treating a patient with fractionated CO2 resurfacing. PMID:23904822

Detection technique of targets for missile defense system

NASA Astrophysics Data System (ADS)

Guo, Hua-ling; Deng, Jia-hao; Cai, Ke-rong

2009-11-01

Ballistic missile defense system (BMDS) is a weapon system for intercepting enemy ballistic missiles. It includes ballistic-missile warning system, target discrimination system, anti-ballistic-missile guidance systems, and command-control communication system. Infrared imaging detection and laser imaging detection are widely used in BMDS for surveillance, target detection, target tracking, and target discrimination. Based on a comprehensive review of the application of target-detection techniques in the missile defense system, including infrared focal plane arrays (IRFPA), ground-based radar detection technology, 3-dimensional imaging laser radar with a photon counting avalanche photodiode (APD) arrays and microchip laser, this paper focuses on the infrared and laser imaging detection techniques in missile defense system, as well as the trends for their future development.

Pulse Shape Correlation for Laser Detection and Ranging (LADAR)

DTIC Science & Technology

2010-03-01

with the incoming measured laser pulse [3]. All of these shapes are symmetric. Siegman and Liu’s findings indicate that the pulse is seldom symmetric...of Engineering, Air Force Institute of Technology (AETC), Wright Pat- terson AFB, OH, March 2007. 10. Siegman , Anthony E. Lasers . University Science...Pulse Shape Correlation for Laser Detection and Ranging (LADAR) THESIS Brian T. Deas, Major, USAF AFIT/GE/ENG/10-07 DEPARTMENT OF THE AIR FORCE AIR

Coherent Doppler Laser Radar: Technology Development and Applications

NASA Technical Reports Server (NTRS)

Kavaya, Michael J.; Arnold, James E. (Technical Monitor)

2000-01-01

NASA's Marshall Space Flight Center has been investigating, developing, and applying coherent Doppler laser radar technology for over 30 years. These efforts have included the first wind measurement in 1967, the first airborne flights in 1972, the first airborne wind field mapping in 1981, and the first measurement of hurricane eyewall winds in 1998. A parallel effort at MSFC since 1982 has been the study, modeling and technology development for a space-based global wind measurement system. These endeavors to date have resulted in compact, robust, eyesafe lidars at 2 micron wavelength based on solid-state laser technology; in a factor of 6 volume reduction in near diffraction limited, space-qualifiable telescopes; in sophisticated airborne scanners with full platform motion subtraction; in local oscillator lasers capable of rapid tuning of 25 GHz for removal of relative laser radar to target velocities over a 25 km/s range; in performance prediction theory and simulations that have been validated experimentally; and in extensive field campaign experience. We have also begun efforts to dramatically improve the fundamental photon efficiency of the laser radar, to demonstrate advanced lower mass laser radar telescopes and scanners; to develop laser and laser radar system alignment maintenance technologies; and to greatly improve the electrical efficiency, cooling technique, and robustness of the pulsed laser. This coherent Doppler laser radar technology is suitable for high resolution, high accuracy wind mapping; for aerosol and cloud measurement; for Differential Absorption Lidar (DIAL) measurements of atmospheric and trace gases; for hard target range and velocity measurement; and for hard target vibration spectra measurement. It is also suitable for a number of aircraft operations applications such as clear air turbulence (CAT) detection; dangerous wind shear (microburst) detection; airspeed, angle of attack, and sideslip measurement; and fuel savings through headwind minimization. In addition to the airborne and space platforms, a coherent Doppler laser radar system in an unmanned aerial vehicle (UAV) could provide battlefield weather and target identification.

New laser technologies in ophthalmology for normalisation of intraocular pressure and correction of refraction

NASA Astrophysics Data System (ADS)

Baum, O. I.; Yuzhakov, A. V.; Bolshunov, A. V.; Siplivyi, V. I.; Khomchik, O. V.; Zheltov, G. I.; Sobol, E. N.

2017-09-01

We present the results of recent studies that develop principally new approaches to solving the problem of visual impairment and provide the basis for new laser technologies in ophthalmology for the treatment of glaucoma, myopia and hypermetropia. The considered theoretical models and optical methods for detecting laser-induced structural changes in eye tissues pave the way to the invention of control systems with feedback, providing efficient and safe laser treatment.

Laser-ultrasonic inspection of hybrid laser-arc welded HSLA-65 steel

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

Lévesque, D.; Rousseau, G.; Monchalin, J.-P.

2014-02-18

The hybrid laser-arc welding (HLAW) process is a relatively low heat input joining technology that combines the synergistic qualities of both the high energy density laser beam for deep penetration and the arc for wide fit-up gap tolerance. This process is especially suitable for the shipbuilding industry where thick-gauge section, long steel plates have been widely used in a butt joint configuration. In this study, preliminary exploration was carried out to detect and visualize the welding defects using laser ultrasonics combined with the synthetic aperture focusing technique (SAFT). Results obtained on 9.3 mm thick butt-welded HSLA-65 steel plates indicated thatmore » the laser-ultrasonic SAFT inspection technique can successfully detect and visualize the presence of porosity, lack of fusion and internal crack defects. This was further confirmed by X-ray digital radiography and metallography. The results obtained clearly show the potential of using the laser-ultrasonic technology for the automated inspection of hybrid laser-arc welds.« less

Laser-ultrasonic inspection of hybrid laser-arc welded HSLA-65 steel

NASA Astrophysics Data System (ADS)

Lévesque, D.; Rousseau, G.; Wanjara, P.; Cao, X.; Monchalin, J.-P.

2014-02-01

The hybrid laser-arc welding (HLAW) process is a relatively low heat input joining technology that combines the synergistic qualities of both the high energy density laser beam for deep penetration and the arc for wide fit-up gap tolerance. This process is especially suitable for the shipbuilding industry where thick-gauge section, long steel plates have been widely used in a butt joint configuration. In this study, preliminary exploration was carried out to detect and visualize the welding defects using laser ultrasonics combined with the synthetic aperture focusing technique (SAFT). Results obtained on 9.3 mm thick butt-welded HSLA-65 steel plates indicated that the laser-ultrasonic SAFT inspection technique can successfully detect and visualize the presence of porosity, lack of fusion and internal crack defects. This was further confirmed by X-ray digital radiography and metallography. The results obtained clearly show the potential of using the laser-ultrasonic technology for the automated inspection of hybrid laser-arc welds.

Low-cost lightweight airborne laser-based sensors for pipeline leak detection and reporting

NASA Astrophysics Data System (ADS)

Frish, Michael B.; Wainner, Richard T.; Laderer, Matthew C.; Allen, Mark G.; Rutherford, James; Wehnert, Paul; Dey, Sean; Gilchrist, John; Corbi, Ron; Picciaia, Daniele; Andreussi, Paolo; Furry, David

2013-05-01

Laser sensing enables aerial detection of natural gas pipeline leaks without need to fly through a hazardous gas plume. This paper describes adaptations of commercial laser-based methane sensing technology that provide relatively low-cost lightweight and battery-powered aerial leak sensors. The underlying technology is near-infrared Standoff Tunable Diode Laser Absorption Spectroscopy (sTDLAS). In one configuration, currently in commercial operation for pipeline surveillance, sTDLAS is combined with automated data reduction, alerting, navigation, and video imagery, integrated into a single-engine single-pilot light fixed-wing aircraft or helicopter platform. In a novel configuration for mapping landfill methane emissions, a miniaturized ultra-lightweight sTDLAS sensor flies aboard a small quad-rotor unmanned aerial vehicle (UAV).

Remote explosive and chemical agent detection using broadly tunable mid-infrared external cavity quantum cascade lasers

NASA Astrophysics Data System (ADS)

Rayner, Timothy; Weida, Miles; Pushkarsky, Michael; Day, Timothy

2007-04-01

Terrorists both with IEDs and suicide bombers are targeting civilian infrastructures such as transportation systems. Although explosive detection technologies exist and are used effectively in aviation, these technologies do not lend themselves well to protecting open architecture soft targets, as they are focused on a checkpoint form factor that limits throughput. However, remote detection of explosives and other chemicals would enable these kinds of targets to be protected without interrupting the flow of commerce. Tunable mid-IR laser technology offers the opportunity to detect explosives and other chemicals remotely and quickly. Most chemical compounds, including explosives, have their fundamental vibrational modes in the mid-infrared region (3 to 15μm). There are a variety of techniques that focus on examining interactions that have proven effective in the laboratory but could never work in the field due to complexity, size, reliability and cost. Daylight Solutions has solved these problems by integrating quantum cascade gain media into external tunable cavities. This has resulted in miniaturized, broadly tunable mid-IR laser sources. The laser sources have a capability to tune to +/- 5% of their center wavelength, which means they can sweep through an entire absorption spectrum to ensure very good detection and false alarm performance compared with fixed wavelength devices. These devices are also highly portable, operate at room temperature, and generate 10's to 100's of mW in optical power, in pulsed and continuous wave configurations. Daylight Solutions is in the process of developing a variety of standoff explosive and chemical weapon detection systems using this technology.

Feasibility of airborne detection of laser-induced fluorescence emissions from green terrestrial plants

NASA Technical Reports Server (NTRS)

Hoge, F. E.; Swift, R. N.; Yungel, J. K.

1983-01-01

The present investigation provides a demonstration of the feasibility of the airborne detection of the laser-induced fluorescence spectral emissions from living terrestrial grasses, shrubs, and trees using existing levels of lidar technology. Airborne studies were performed to ascertain system requirements necessary to detect laser-induced fluorescence from living terrestrial plants, to assess the practical acquisition of useful single-shot laser-induced fluorescence (LIF) waveforms over vegetative canopies, and to determine the comparative suitability of laser system, airborne platform, and terrestrial environmental parameters. The field experiment was conducted on May 3, 1982, over the northern portion of Wallops Island, VA. Attention is given to airborne lidar results and the description of laboratory investigations.

Application and the key technology on high power fiber-optic laser in laser weapon

NASA Astrophysics Data System (ADS)

Qu, Zhou; Li, Qiushi; Meng, Haihong; Sui, Xin; Zhang, Hongtao; Zhai, Xuhua

2014-12-01

The soft-killing laser weapon plays an important role in photoelectric defense technology. It can be used for photoelectric detection, search, blinding of photoelectric sensor and other devices on fire control and guidance devices, therefore it draws more and more attentions by many scholars. High power fiber-optic laser has many virtues such as small volume, simple structure, nimble handling, high efficiency, qualified light beam, easy thermal management, leading to blinding. Consequently, it may be used as the key device of soft-killing laser weapon. The present study introduced the development of high power fiber-optic laser and its main features. Meanwhile the key technology of large mode area (LMA) optical fiber design, the beam combination technology, double-clad fiber technology and pumping optical coupling technology was stated. The present study is aimed to design high doping LMA fiber, ensure single mode output by increasing core diameter and decrease NA. By means of reducing the spontaneous emission particle absorbed by fiber core and Increasing the power density in the optical fiber, the threshold power of nonlinear effect can increase, and the power of single fiber will be improved. Meantime, high power will be obtained by the beam combination technology. Application prospect of high power fiber laser in photoelectric defense technology was also set forth. Lastly, the present study explored the advantages of high power fiber laser in photoelectric defense technology.

Study of ocean red tide multi-parameter monitoring technology based on double-wavelength airborne lidar system

NASA Astrophysics Data System (ADS)

Lin, Hong; Wang, Xinming; Liang, Kun

2010-10-01

For monitoring and forecasting of the ocean red tide in real time, a marine environment monitoring technology based on the double-wavelength airborne lidar system is proposed. An airborne lidar is father more efficient than the traditional measure technology by the boat. At the same time, this technology can detect multi-parameter about the ocean red tide by using the double-wavelength lidar.It not only can use the infrared laser to detect the scattering signal under the water and gain the information about the red tise's density and size, but also can use the blue-green laser to detect the Brillouin scattering signal and deduce the temperature and salinity of the seawater.The red tide's density detecting model is firstly established by introducing the concept about the red tide scattering coefficient based on the Mie scattering theory. From the Brillouin scattering theory, the relationship about the blue-green laser's Brillouin scattering frequency shift value and power value with the seawater temperature and salinity is found. Then, the detecting mode1 of the saewater temperature and salinity can be established. The value of the red tide infrared scattering signal is evaluated by the simulation, and therefore the red tide particles' density can be known. At the same time, the blue-green laser's Brillouin scattering frequency shift value and power value are evaluated by simulating, and the temperature and salinity of the seawater can be known. Baed on the multi-parameters, the ocean red tide's growth can be monitored and forecasted.

Quantitative Detection of Combustion Species using Ultra-Violet Diode Lasers

NASA Technical Reports Server (NTRS)

Pilgrim, J. S.; Peterson, K. A.

2001-01-01

Southwest Sciences is developing a new microgravity combustion diagnostic based on UV diode lasers. The instrument will allow absolute concentration measurements of combustion species on a variety of microgravity combustion platforms including the Space Station. Our approach uses newly available room temperature UV diode lasers, thereby keeping the instrument compact, rugged and energy efficient. The feasibility of the technique was demonstrated by measurement of CH radicals in laboratory flames. Further progress in fabrication technology of UV diode lasers at shorter wavelengths and higher power will result in detection of transient species in the deeper UV. High sensitivity detection of combustion radicals is provided with wavelength modulation absorption spectroscopy.

Noncontact Acousto-Ultrasonics for Material Characterization

NASA Technical Reports Server (NTRS)

Kautz, Harold E.

1998-01-01

A NdYAG 1064 nm, laser pulse was employed to produce ultrasonic waves in specimens of SiC/SiC and SiC/Ti 6-4 composites which are high temperature materials of interest for aerospace applications. Air coupled transducers were used to detect and collect the signals used for acousto-ultrasonic analysis. Conditions for detecting ultrasonic decay signals were examined. The results were compared to those determined on the same specimens with contact coupling. Some non-contact measurements were made employing conventional air focused detectors. Others were performed with a more novel micromachined capacitance transducer. Concerns of the laser-in technology include potential destructiveness of the laser pulse. Repeated laser pulsing at the same location does lead to deterioration of the ultrasonic signal in some materials, but seems to recover with time. Also, unlike contact AU, the frequency regime employed is a function of laser-material interaction rather than the choice of transducers. Concerns of the air coupled-out technology include the effect of air attenuation. This imposes a practical upper limit to frequency of detection. In the case of the experimental specimens studied ultrasonic decay signals could be imaged satisfactorily.

Quantum Cascade Laser (QCL) based sensor for the detection of explosive compounds

NASA Astrophysics Data System (ADS)

Normand, Erwan; Howieson, Iain; McCulloch, Michael; Black, Paul

2006-09-01

Following Cascade Technologies first success at using Quantum Cascade Lasers (QCL) for trace gas detection in the continuous emission monitoring market, the core technology platform is now being developed towards homeland security applications. This paper will highlight the potential of QCL based trace gas sensor for detecting vapours of explosives. Furthermore we will present results that let foresee the use of such technologies at addressing security gaps for protection against terrorism in infrastructures where high throughput screening of individuals or items is required. Preliminary measurements have shown that rapid identification, or fingerprinting, of explosive is achievable in 10ms at extrapolated sensitivities in the sub-part per billion range. The experiments were carried out with support form the Home Office Scientific Development Branch (HOSDB) in the UK and were focused at selecting a variety of explosive compounds and showing their detection using a novel sniffer platform system based on the use of quantum cascade lasers. Preliminary studies on the technology have indicated that direct fingerprinting (detection - identification) of explosive compounds such as NG and tagging agents such as EGDN by sniffing surrounding ambient air is achievable. Furthermore these studies have also indicated that detection of such compounds on packaging used to ship the sealed compounds is possible, making this platform a strong contender for detection through cross contamination on material that have been in contact with each other. Additionally, it was also possible to detect breakdown products associated with sample material NG providing a further capability that could be exploited to enhance the detection and identification of explosive compounds.

Research on airborne infrared leakage detection of natural gas pipeline

NASA Astrophysics Data System (ADS)

Tan, Dongjie; Xu, Bin; Xu, Xu; Wang, Hongchao; Yu, Dongliang; Tian, Shengjie

2011-12-01

An airborne laser remote sensing technology is proposed to detect natural gas pipeline leakage in helicopter which carrying a detector, and the detector can detect a high spatial resolution of trace of methane on the ground. The principle of the airborne laser remote sensing system is based on tunable diode laser absorption spectroscopy (TDLAS). The system consists of an optical unit containing the laser, camera, helicopter mount, electronic unit with DGPS antenna, a notebook computer and a pilot monitor. And the system is mounted on a helicopter. The principle and the architecture of the airborne laser remote sensing system are presented. Field test experiments are carried out on West-East Natural Gas Pipeline of China, and the results show that airborne detection method is suitable for detecting gas leak of pipeline on plain, desert, hills but unfit for the area with large altitude diversification.

Inner structure detection by optical tomography technology based on feedback of microchip Nd:YAG lasers.

PubMed

Xu, Chunxin; Zhang, Shulian; Tan, Yidong; Zhao, Shijie

2013-05-20

We describe a new optical tomography technology based on feedback of microchip Nd:YAG lasers. In the case of feedback light frequency-shifted, light can be magnified by a fact of 10(6) in the Nd:YAG microchip lasers, which makes it possible to realize optical tomography with a greater depth than current optical tomography. The results of the measuring and imaging of kinds of samples are presented, which demonstrate the feasibility and potential of this approach in the inner structure detection. The system has a lateral resolution of ~1 μm, a vertical resolution of 15 μm and a longitudinal scanning range of over 10mm.

DAWN Coherent Wind Profiling Lidar Flights on NASA's DC-8 During GRIP

NASA Technical Reports Server (NTRS)

Kavaya, Michael J.; Beyon, Jeffrey Y.; Creary, Garfield A.; Koch, Grady J.; Petros, Mulugeta; Petzar, Paul J.; Singh, Upendra N.; Trieu, Bo C.; Yu, Jirong

2011-01-01

Almost from their invention, lasers have been used to measure the velocity of wind and objects; over distances of cm to 10s of km. Long distance (remote) sensing of wind has been accomplished with continuous-wave (CW), focused pulsed, and collimated pulsed lasers; with direct and coherent (heterodyne) optical detection; and with a multitude of laser wavelengths. Airborne measurement of wind with pulsed, coherent-detection lidar was first performed in 1971 with a CW CO2 laser1, in 1972 with a pulsed CO2 laser2, in 1993 with a pulsed 2-micron laser3, and in 1999 with a pulsed CO2 laser and nadir-centered conical scanning4. Of course there were many other firsts and many other groups doing lidar wind remote sensing with coherent and direct detection. A very large FOM coherent wind lidar has been built by LaRC and flown on a DC-8. However a burn on the telescope secondary mirror prevented the full demonstration of high FOM. Both the GRIP science product and the technology and technique demonstration from aircraft are important to NASA. The technology and technique demonstrations contribute to our readiness for the 3D Winds space mission. The data analysis is beginning and we hope to present results at the conference.

Gas sensing using wavelength modulation spectroscopy

NASA Astrophysics Data System (ADS)

Viveiros, D.; Ribeiro, J.; Flores, D.; Ferreira, J.; Frazao, O.; Santos, J. L.; Baptista, J. M.

2014-08-01

An experimental setup has been developed for different gas species sensing based on the Wavelength Modulation Spectroscopy (WMS) principle. The target is the measurement of ammonia, carbon dioxide and methane concentrations. The WMS is a rather sensitive technique for detecting atomic/molecular species presenting the advantage that it can be used in the near-infrared region using optical telecommunications technology. In this technique, the laser wavelength and intensity are modulated applying a sine wave signal through the injection current, which allows the shift of the detection bandwidth to higher frequencies where laser intensity noise is reduced. The wavelength modulated laser light is tuned to the absorption line of the target gas and the absorption information can be retrieved by means of synchronous detection using a lock-in amplifier, where the amplitude of the second harmonic of the laser modulation frequency is proportional to the gas concentration. The amplitude of the second harmonic is normalised by the average laser intensity and detector gain through a LabVIEW® application, where the main advantage of normalising is that the effects of laser output power fluctuations and any variations in laser transmission, or optical-electrical detector gain are eliminated. Two types of sensing heads based on free space light propagation with different optical path length were used, permitting redundancy operation and technology validation.

Status of 2 micron laser technology program

NASA Technical Reports Server (NTRS)

Storm, Mark

1991-01-01

The status of 2 micron lasers for windshear detection is described in viewgraph form Theoretical atmospheric and instrument system studies have demonstrated that the 2.1 micron Ho:YAG lasers can effectively measure wind speeds in both wet and dry conditions with accuracies of 1 m/sec. Two micron laser technology looks very promising in the near future, but several technical questions remain. The Ho:YAG laser would be small, compact, and efficient, requiring little or no maintenance. Since the Ho:YAG laser is laser diode pumped and has no moving part, the lifetime of this laser would be directly related to the diode laser lifetimes which can perform in excess of 10,000 hours. Efficiencies of 3 to 12 percent are expected, but laser demonstrations confirming the ability to Q-switch this laser are required. Coherent laser operation has been demonstrated for both the CW and Q-switched lasers.

Human-technology interaction for standoff IED detection

NASA Astrophysics Data System (ADS)

Zhang, Evan; Zou, Yiyang; Zachrich, Liping; Fulton, Jack

2011-03-01

IEDs kill our soldiers and innocent people every day. Lessons learned from Iraq and Afghanistan clearly indicated that IEDs cannot be detected/defeated by technology alone; human-technology interaction must be engaged. In most cases, eye is the best detector, brain is the best computer, and technologies are tools, they must be used by human being properly then can achieve full functionality. In this paper, a UV Raman/fluorescence, CCD and LWIR 3 sensor fusion system for standoff IED detection and a handheld fusion system for close range IED detection are developed and demonstrated. We must train solders using their eyes or CCD/LWIR cameras to do wide area search while on the move to find small suspected area first then use the spectrometer because the laser spot is too small, to scan a one-mile long and 2-meter wide road needs 185 days although our fusion system can detect the IED in 30m with 1s interrogating time. Even if the small suspected area (e.g., 0.5mx0.5m) is found, human eyes still cannot detect the IED, soldiers must use or interact with the technology - laser based spectrometer to scan the area then they are able to detect and identify the IED in 10 minutes not 185 days. Therefore, the human-technology interaction approach will be the best solution for IED detection.

[Analysis and experimental verification of sensitivity and SNR of laser warning receiver].

PubMed

Zhang, Ji-Long; Wang, Ming; Tian, Er-Ming; Li, Xiao; Wang, Zhi-Bin; Zhang, Yue

2009-01-01

In order to countermeasure increasingly serious threat from hostile laser in modern war, it is urgent to do research on laser warning technology and system, and the sensitivity and signal to noise ratio (SNR) are two important performance parameters in laser warning system. In the present paper, based on the signal statistical detection theory, a method for calculation of the sensitivity and SNR in coherent detection laser warning receiver (LWR) has been proposed. Firstly, the probabilities of the laser signal and receiver noise were analyzed. Secondly, based on the threshold detection theory and Neyman-Pearson criteria, the signal current equation was established by introducing detection probability factor and false alarm rate factor, then, the mathematical expressions of sensitivity and SNR were deduced. Finally, by using method, the sensitivity and SNR of the sinusoidal grating laser warning receiver developed by our group were analyzed, and the theoretic calculation and experimental results indicate that the SNR analysis method is feasible, and can be used in performance analysis of LWR.

ALMDS laser system

NASA Astrophysics Data System (ADS)

Kushina, Mark E.; Heberle, Geoff; Hope, Michael; Hall, David; Bethel, Michael; Calmes, Lonnie K.

2003-06-01

The ALMDS (Airborne Laser Mine Detection System) has been developed utilizing a solid-state laser operating at 532nm for naval mine detection. The laser system is integrated into a pod that mounts externally on a helicopter. This laser, along with other receiver systems, enables detailed underwater bathymetry. CEO designs and manufactures the laser portion of this system. Arete Associates integrates the laser system into the complete LIDAR package that utilizes sophisticated streak tube detection technology. Northrop Grumman is responsible for final pod integration. The laser sub-system is comprised of two separate parts: the LTU (Laser Transmitter Unit) and the LEU (Laser Electronics Unit). The LTU and LEU are undergoing MIL-STD-810 testing for vibration, shock, temperature storage and operation extremes, as well as MIL-STD-704E electrical power testing and MIL-STD-461E EMI testing. The Nd:YAG MOPA laser operates at 350 Hz pulse repetition frequency at 45 Watts average 532nm power and is controlled at the system level from within the helicopter. Power monitor circuits allow real time laser health monitoring, which enables input parameter adjustments for consistent laser behavior.

[Application Progress of Three-dimensional Laser Scanning Technology in Medical Surface Mapping].

PubMed

Zhang, Yonghong; Hou, He; Han, Yuchuan; Wang, Ning; Zhang, Ying; Zhu, Xianfeng; Wang, Mingshi

2016-04-01

The booming three-dimensional laser scanning technology can efficiently and effectively get spatial three-dimensional coordinates of the detected object surface and reconstruct the image at high speed,high precision and large capacity of information.Non-radiation,non-contact and the ability of visualization make it increasingly popular in three-dimensional surface medical mapping.This paper reviews the applications and developments of three-dimensional laser scanning technology in medical field,especially in stomatology,plastic surgery and orthopedics.Furthermore,the paper also discusses the application prospects in the future as well as the biomedical engineering problems it would encounter with.

Light detection and ranging (LIDAR): an emerging tool for multiple resource inventory.

Treesearch

Stephen E. Reutebuch; Hans-Erik Andersen; Robert J. McGaughey

2005-01-01

Airborne laser scanning of forests has been shown to provide accurate terrain models and, at the same time, estimates of multiple resource inventory variables through active sensing of three-dimensional (3D) forest vegetation. Brief overviews of airborne laser scanning technology [often referred to as "light detection and ranging" (LIDAR)] and research...

Laser radar: historical prospective-from the East to the West

NASA Astrophysics Data System (ADS)

Molebny, Vasyl; McManamon, Paul; Steinvall, Ove; Kobayashi, Takao; Chen, Weibiao

2017-03-01

This article discusses the history of laser radar development in America, Europe, and Asia. Direct detection laser radar is discussed for range finding, designation, and topographic mapping of Earth and of extraterrestrial objects. Coherent laser radar is discussed for environmental applications, such as wind sensing and for synthetic aperture laser radar development. Gated imaging is discussed through scattering layers for military, medical, and security applications. Laser microradars have found applications in intravascular studies and in ophthalmology for vision correction. Ghost laser radar has emerged as a new technology in theoretical and simulation applications. Laser radar is now emerging as an important technology for applications such as self-driving cars and unmanned aerial vehicles. It is also used by police to measure speed, and in gaming, such as the Microsoft Kinect.

Measurement of Irradiated Pyroprocessing Samples via Laser Induced Breakdown Spectroscopy

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

Phongikaroon, Supathorn

The primary objective of this research is to develop an applied technology and provide an assessment to remotely measure and analyze the real time or near real time concentrations of used nuclear fuel (UNF) dissolute in electrorefiners. Here, Laser-Induced Breakdown Spectroscopy (LIBS), in UNF pyroprocessing facilities will be investigated. LIBS is an elemental analysis method, which is based on the emission from plasma generated by focusing a laser beam into the medium. This technology has been reported to be applicable in the media of solids, liquids (includes molten metals), and gases for detecting elements of special nuclear materials. The advantagesmore » of applying the technology for pyroprocessing facilities are: (i) Rapid real-time elemental analysis|one measurement/laser pulse, or average spectra from multiple laser pulses for greater accuracy in < 2 minutes; (ii) Direct detection of elements and impurities in the system with low detection limits|element specific, ranging from 2-1000 ppm for most elements; and (iii) Near non-destructive elemental analysis method (about 1 g material). One important challenge to overcome is achieving high-resolution spectral analysis to quantitatively analyze all important fission products and actinides. Another important challenge is related to accessibility of molten salt, which is heated in a heavily insulated, remotely operated furnace in a high radiation environment with an argon atmosphere.« less

Research on the high-precision non-contact optical detection technology for banknotes

NASA Astrophysics Data System (ADS)

Jin, Xiaofeng; Liang, Tiancai; Luo, Pengfeng; Sun, Jianfeng

2015-09-01

The technology of high-precision laser interferometry was introduced for optical measurement of the banknotes in this paper. Taking advantage of laser short wavelength and high sensitivity, information of adhesive tape and cavity about the banknotes could be checked efficiently. Compared with current measurement devices, including mechanical wheel measurement device, Infrared measurement device, ultrasonic measurement device, the laser interferometry measurement has higher precision and reliability. This will improve the ability of banknotes feature information in financial electronic equipment.

Laser Shearography Inspection of TPS (Thermal Protection System) Cork on RSRM (Reusable Solid Rocket Motors)

NASA Technical Reports Server (NTRS)

Lingbloom, Mike; Plaia, Jim; Newman, John

2006-01-01

Laser Shearography is a viable inspection method for detection of de-bonds and voids within the external TPS (thermal protection system) on to the Space Shuttle RSRM (reusable solid rocket motors). Cork samples with thicknesses up to 1 inch were tested at the LTI (Laser Technology Incorporated) laboratory using vacuum-applied stress in a vacuum chamber. The testing proved that the technology could detect cork to steel un-bonds using vacuum stress techniques in the laboratory environment. The next logical step was to inspect the TPS on a RSRM. Although detailed post flight inspection has confirmed that ATK Thiokol's cork bonding technique provides a reliable cork to case bond, due to the Space Shuttle Columbia incident there is a great interest in verifying bond-lines on the external TPS. This interest provided and opportunity to inspect a RSRM motor with Laser Shearography. This paper will describe the laboratory testing and RSRM testing that has been performed to date. Descriptions of the test equipment setup and techniques for data collection and detailed results will be given. The data from the test show that Laser Shearography is an effective technology and readily adaptable to inspect a RSRM.

Laser-Ultrasonic Testing and its Applications to Nuclear Reactor Internals

NASA Astrophysics Data System (ADS)

Ochiai, M.; Miura, T.; Yamamoto, S.

2008-02-01

A new nondestructive testing technique for surface-breaking microcracks in nuclear reactor components based on laser-ultrasonics is developed. Surface acoustic wave generated by Q-switched Nd:YAG laser and detected by frequency-stabilized long pulse laser coupled with confocal Fabry-Perot interferometer is used to detect and size the cracks. A frequency-domain signal processing is developed to realize accurate sizing capability. The laser-ultrasonic testing allows the detection of surface-breaking microcrack having a depth of less than 0.1 mm, and the measurement of their depth with an accuracy of 0.2 mm when the depth exceeds 0.5 mm including stress corrosion cracking. The laser-ultrasonic testing system combined with laser peening system, which is another laser-based maintenance technology to improve surface stress, for inner surface of small diameter tube is developed. The generation laser in the laser-ultrasonic testing system can be identical to the laser source of the laser peening. As an example operation of the system, the system firstly works as the laser-ultrasonic testing mode and tests the inner surface of the tube. If no cracks are detected, the system then changes its work mode to the laser peening and improves surface stress to prevent crack initiation. The first nuclear industrial application of the laser-ultrasonic testing system combined with the laser peening was completed in Japanese nuclear power plant in December 2004.

Single-silicon CCD-CMOS platform for multi-spectral detection from terahertz to x-rays.

PubMed

Shalaby, Mostafa; Vicario, Carlo; Hauri, Christoph P

2017-11-15

Charge-coupled devices (CCDs) are a well-established imaging technology in the visible and x-ray frequency ranges. However, the small quantum photon energies of terahertz radiation have hindered the use of this mature semiconductor technological platform in this frequency range, leaving terahertz imaging totally dependent on low-resolution bolometer technologies. Recently, it has been shown that silicon CCDs can detect terahertz photons at a high field, but the detection sensitivity is limited. Here we show that silicon, complementary metal-oxide-semiconductor (CMOS) technology offers enhanced detection sensitivity of almost two orders of magnitude, compared to CCDs. Our findings allow us to extend the low-frequency terahertz cutoff to less than 2 THz, nearly closing the technological gap with electronic imagers operating up to 1 THz. Furthermore, with the silicon CCD/CMOS technology being sensitive to mid-infrared (mid-IR) and the x-ray ranges, we introduce silicon as a single detector platform from 1 EHz to 2 THz. This overcomes the present challenge in spatially overlapping a terahertz/mid-IR pump and x-ray probe radiation at facilities such as free electron lasers, synchrotron, and laser-based x-ray sources.

[The error analysis and experimental verification of laser radar spectrum detection and terahertz time domain spectroscopy].

PubMed

Liu, Wen-Tao; Li, Jing-Wen; Sun, Zhi-Hui

2010-03-01

Terahertz waves (THz, T-ray) lie between far-infrared and microwave in electromagnetic spectrum with frequency from 0.1 to 10 THz. Many chemical agent explosives show characteristic spectral features in the terahertz. Compared with conventional methods of detecting a variety of threats, such as weapons and chemical agent, THz radiation is low frequency and non-ionizing, and does not give rise to safety concerns. The present paper summarizes the latest progress in the application of terahertz time domain spectroscopy (THz-TDS) to chemical agent explosives. A kind of device on laser radar detecting and real time spectrum measuring was designed which measures the laser spectrum on the bases of Fourier optics and optical signal processing. Wedge interferometer was used as the beam splitter to wipe off the background light and detect the laser and measure the spectrum. The result indicates that 10 ns laser radar pulse can be detected and many factors affecting experiments are also introduced. The combination of laser radar spectrum detecting, THz-TDS, modern pattern recognition and signal processing technology is the developing trend of remote detection for chemical agent explosives.

Detection of Neisseria meningitidis in cerebrospinal fluid using a multiplex PCR and the Luminex detection technology.

PubMed

Møller, Jens Kjølseth

2012-01-01

Rapid clinical and laboratory diagnoses are the foundation for a successful management of serious infections with Neisseria meningitidis. A species-specific multiplex polymerase chain reaction (PCR) coupled with fluidic microarrays using microbeads (the Luminex xMAP™ Technology) can detect pathogens most frequently found in the cerebrospinal fluid of patients. The Luminex suspension array system uniquely combines flow cytometry, microspheres, laser technology, digital signal processing, and traditional chemistry. In this method, the reaction is carried out in one vessel, in which distinctly color-coded bead sets, each conjugated with a different specific nucleic acid reactant, are hybridized with the PCR products, and a reporter molecule is used to quantify the interaction. The flow-based Luminex array reader identifies each reaction (bead set) after excitation by a red classification laser. Reporter signals from each reaction are simultaneously quantified by fluorescence generated by a green reporter laser. This nonculture, multiplex assay may prove to be an important tool for optimal laboratory diagnosis, not only of meningococcal meningitis, but also of meningitis caused by other bacterial or viral pathogens.

Laser Spot Center Detection and Comparison Test

NASA Astrophysics Data System (ADS)

Zhu, Jun; Xu, Zhengjie; Fu, Deli; Hu, Cong

2018-04-01

High efficiency and precision of the pot center detection are the foundations of avionics instrument navigation and optics measurement basis for many applications. It has noticeable impact on overall system performance. Among them, laser spot detection is very important in the optical measurement technology. In order to improve the low accuracy of the spot center position, the algorithm is improved on the basis of the circle fitting. The pretreatment is used by circle fitting, and the improved adaptive denoising filter for TV repair technology can effectively improves the accuracy of the spot center position. At the same time, the pretreatment and de-noising can effectively reduce the influence of Gaussian white noise, which enhances the anti-jamming capability.

Handheld lasers allow efficient detection of fluorescent marked organisms in the field.

PubMed

Rice, Kevin B; Fleischer, Shelby J; De Moraes, Consuelo M; Mescher, Mark C; Tooker, John F; Gish, Moshe

2015-01-01

Marking organisms with fluorescent dyes and powders is a common technique used in ecological field studies that monitor movement of organisms to examine life history traits, behaviors, and population dynamics. External fluorescent marking is relatively inexpensive and can be readily employed to quickly mark large numbers of individuals; however, the ability to detect marked organisms in the field at night has been hampered by the limited detection distances provided by portable fluorescent ultraviolet lamps. In recent years, significant advances in LED lamp and laser technology have led to development of powerful, low-cost ultraviolet light sources. In this study, we evaluate the potential of these new technologies to improve detection of fluorescent-marked organisms in the field and to create new possibilities for tracking marked organisms in visually challenging environments such as tree canopies and aquatic habitats. Using handheld lasers, we document a method that provides a fivefold increase in detection distance over previously available technologies. This method allows easy scouting of tree canopies (from the ground), as well as shallow aquatic systems. This novel detection method for fluorescent-marked organisms thus promises to significantly enhance the use of fluorescent marking as a non-destructive technique for tracking organisms in natural environments, facilitating field studies that aim to document otherwise inaccessible aspects of the movement, behavior, and population dynamics of study organisms, including species with significant economic impacts or relevance for ecology and human health.

Laser discrimination by stimulated emission of a phosphor

NASA Technical Reports Server (NTRS)

Mathur, V. K.; Chakrabarti, K.

1991-01-01

A method for discriminating sources of UV, near infrared, and far infrared laser radiation was discovered. This technology is based on the use of a single magnesium sulfide phosphor doubly doped with rare earth ions, which is thermally/optically stimulated to generate colors correlatable to the incident laser radiation. The phosphor, after initial charging by visible light, exhibits green stimulated luminescence when exposed to a near infrared source (Nd: YAG laser). On exposure to far infrared sources (CO2 laser) the phosphor emission changes to orange color. A UV laser produces both an orange red as well as green color. A device using this phosphor is useful for detecting the laser and for discriminating between the near infrared, far infrared, and UV lasers. The technology is also capable of infrared laser diode beam profiling since the radiation source leaves an imprint on the phosphor that can be photographed. Continued development of the technology offers potential for discrimination between even smaller bandwidths within the infrared spectrum, a possible aid to communication or wavemixing devices that need to rapidly identify and process optical signals.

Near infrared lasers in flow cytometry.

PubMed

Telford, William G

2015-07-01

Technology development in flow cytometry has closely tracked laser technology, the light source that flow cytometers almost exclusively use to excite fluorescent probes. The original flow cytometers from the 1970s and 1980s used large water-cooled lasers to produce only one or two laser lines at a time. Modern cytometers can take advantage of the revolution in solid state laser technology to use almost any laser wavelength ranging from the ultraviolet to the near infrared. Commercial cytometers can now be equipped with many small solid state lasers, providing almost any wavelength needed for cellular analysis. Flow cytometers are now equipped to analyze 20 or more fluorescent probes simultaneously, requiring multiple laser wavelengths. Instrument developers are now trying to increase this number by designing fluorescent probes that can be excited by laser wavelength at the "edges" of the visible light range, in the near ultraviolet and near-infrared region. A variety of fluorescent probes have been developed that excite with violet and long wavelength ultraviolet light; however, the near-infrared range (660-800 nm) has yet seen only exploitation in flow cytometry. Fortunately, near-infrared laser diodes and other solid state laser technologies appropriate for flow cytometry have been in existence for some time, and can be readily incorporated into flow cytometers to accelerate fluorescent probe development. The near infrared region represents one of the last "frontiers" to maximize the number of fluorescent probes that can be analyzed by flow cytometry. In addition, near infrared fluorescent probes used in biomedical tracking and imaging could also be employed for flow cytometry with the correct laser wavelengths. This review describes the available technology, including lasers, fluorescent probes and detector technology optimal for near infrared signal detection. Published by Elsevier Inc.

Multi-point laser coherent detection system and its application on vibration measurement

NASA Astrophysics Data System (ADS)

Fu, Y.; Yang, C.; Xu, Y. J.; Liu, H.; Yan, K.; Guo, M.

2015-05-01

Laser Doppler vibrometry (LDV) is a well-known interferometric technique to measure the motions, vibrations and mode shapes of machine components and structures. The drawback of commercial LDV is that it can only offer a pointwise measurement. In order to build up a vibrometric image, a scanning device is normally adopted to scan the laser point in two spatial axes. These scanning laser Doppler vibrometers (SLDV) assume that the measurement conditions remain invariant while multiple and identical, sequential measurements are performed. This assumption makes SLDVs impractical to do measurement on transient events. In this paper, we introduce a new multiple-point laser coherent detection system based on spatial-encoding technology and fiber configuration. A simultaneous vibration measurement on multiple points is realized using a single photodetector. A prototype16-point laser coherent detection system is built and it is applied to measure the vibration of various objects, such as body of a car or a motorcycle when engine is on and under shock tests. The results show the prospect of multi-point laser coherent detection system in the area of nondestructive test and precise dynamic measurement.

Biomedical Investigations with Laser-Polarized Noble Gas Magnetic Resonance

NASA Technical Reports Server (NTRS)

Walsworth, Ronald L.

2003-01-01

We pursued advanced technology development of laser-polarized noble gas nuclear magnetic resonance (NMR) as a novel biomedical imaging tool for ground-based and eventually space-based application. This new multidisciplinary technology enables high-resolution gas-space magnetic resonance imaging (MRI)-e.g., of lung ventilation-as well as studies of tissue perfusion. In addition, laser-polarized noble gases (3He and 129Xe) do not require a large magnetic field for sensitive detection, opening the door to practical MRI at very low magnetic fields with an open, lightweight, and low-power device. We pursued two technology development specific aims: (1) development of low-field (less than 0.01 T) noble gas MRI of humans; and (2) development of functional MRI of the lung using laser-polarized noble gas and related techniques.

Emerging enhanced imaging technologies of the esophagus: spectroscopy, confocal laser endomicroscopy, and optical coherence tomography.

PubMed

Robles, Lourdes Y; Singh, Satish; Fisichella, Piero Marco

2015-05-15

Despite advances in diagnoses and therapy, esophageal adenocarcinoma remains a highly lethal neoplasm. Hence, a great interest has been placed in detecting early lesions and in the detection of Barrett esophagus (BE). Advanced imaging technologies of the esophagus have then been developed with the aim of improving biopsy sensitivity and detection of preplastic and neoplastic cells. The purpose of this article was to review emerging imaging technologies for esophageal pathology, spectroscopy, confocal laser endomicroscopy (CLE), and optical coherence tomography (OCT). We conducted a PubMed search using the search string "esophagus or esophageal or oesophageal or oesophagus" and "Barrett or esophageal neoplasm" and "spectroscopy or optical spectroscopy" and "confocal laser endomicroscopy" and "confocal microscopy" and "optical coherence tomography." The first and senior author separately reviewed all articles. Our search identified: 19 in vivo studies with spectroscopy that accounted for 1021 patients and 4 ex vivo studies; 14 clinical CLE in vivo studies that accounted for 941 patients and 1 ex vivo study with 13 patients; and 17 clinical OCT in vivo studies that accounted for 773 patients and 2 ex vivo studies. Human studies using spectroscopy had a very high sensitivity and specificity for the detection of BE. CLE showed a high interobserver agreement in diagnosing esophageal pathology and an accuracy of predicting neoplasia. We also found several clinical studies that reported excellent diagnostic sensitivity and specificity for the detection of BE using OCT. Advanced imaging technology for the detection of esophageal lesions is a promising field that aims to improve the detection of early esophageal lesions. Although advancing imaging techniques improve diagnostic sensitivities and specificities, their integration into diagnostic protocols has yet to be perfected. Copyright © 2015 Elsevier Inc. All rights reserved.

New technologies in dentistry

NASA Astrophysics Data System (ADS)

Zanin, Fatima A. A.; Brugnera, Aldo, Jr.; Pecora, Jesus D.

1999-05-01

The technology in dentistry has been developed significantly lately, increasing the technological level of new materials, methods and equipment have been developed. Undoubtedly the CO2 laser has contributed to this evolution particular to the treatment of the infected dentin. CO2 laser can sterilize and promote increase 6 to 8 times of dentin resistance, through the transformation the hydroxyapatite in calcium-phosphato-hydroxyapatite. We can reassure our patients about the use of pulsed CO2 laser due to better preservation of dental structure and its benefits permitting advanced esthetic treatments. The CEREC system, registers a tri-dimensional image of the preparation through a scan system, and sends it to the computer and the operator will edit the restorations so the equipment will finish porcelain restoration. The authors used a new laser 650 nm for caries detection and the other low lever laser (670 nm and 730 nm) considered an auxiliary method to prevent and treat the hypersensitivity in dentin.

Research progress of free space coherent optical communication

NASA Astrophysics Data System (ADS)

Tan, Zhenkun; Ke, Xizheng

2018-02-01

This paper mainly introduces the research progress of free space coherent optical communication in Xi'an University of Technology. In recent years, the research on the outer modulation technology of the laser, free-space-to-fiber coupling technique, the design of transmitting and receiving optical antenna, adaptive optical technology with or without wave-front sensor, automatic polarization control technology, frequency stabilization technology, heterodyne detection technology and high speed signal processing technology. Based on the above related research, the digital signal modulation, transmission, detection and data recovery are realized by the heterodyne detection technology in the free space optical communication system, and finally the function of smooth viewing high-definition video is realized.

Ultrafast Laser Interaction Processes for Libs and Other Sensing Technologies

DTIC Science & Technology

2013-04-05

Wang. Propagation of ultrashort pulses through water, Optics Express, (02 2007): . doi: 12/02/2009 8.00 Z. Chen, S. Mao. Femtosecond laser -induced...Richardson, "Nd:YAG-CO2 double- pulse laser -induced breakdown spectroscopy for explosive residues detection" SPIE Defense, Security, Sensing; Orlando, FL... Ultrashort Pulse Laser Workshop, Directed Energy Professional Society; Newton, MA, USA; 06/29,2009. 63. Martin C. Richardson, Michael Sigman

Ultrafast Laser Interaction Processes for LIBS and Other Sensing Technologies

DTIC Science & Technology

2013-04-05

Propagation of ultrashort pulses through water, Optics Express, (02 2007): . doi: 12/02/2009 8.00 Z. Chen, S. Mao. Femtosecond laser -induced electronic...CO2 double- pulse laser -induced breakdown spectroscopy for explosive residues detection" SPIE Defense, Security, Sensing; Orlando, FL, USA; 04/07...Matthieu Baudelet, Michael Sigman, Paul J Dagdigian, Martin C. Richardson, "Nd:YAG-CO2 Double- Pulse Laser Induced Breakdown Spectroscopy for Explosive

Light detection and ranging (LiDAR) technology evaluation.

DOT National Transportation Integrated Search

2010-10-01

Evaluation project was undertaken to provide an analysis on the current state of Laser based technology and its applicability, : potential accuracies and information content with respect to Missouri Department of Transportation( MODOT) applications.

Technology and the Environment

NASA Technical Reports Server (NTRS)

1977-01-01

Forest Service officials consulted NASA and found a solution in the application of laser technology originally developed for satellites. NASA/Goddard built a system called a "laser range pole," a portable battery operated back-packed device that allows direct sightings no matter how rough the intervening terrain or how thick the forest. The equipment consists of a laser transmitter and a receiver. From a given property marker, the transmitter pulses a laser beam vertically, several thousand feet in some cases. At a second surveying point about a mile away, the receiver detects the laser pulse high above the trees, and locks in on the exact direction. Thus provided a bearing between the two points, a ground crew can extend the border line back to the sending point by conventional surveying techniques.

Fiber Laser methane sensor with the function of self-diagnose

NASA Astrophysics Data System (ADS)

Li, Yan-fang; Wei, Yu-bin; Shang, Ying; Wang, Chang; Liu, Tong-yu

2012-02-01

Using the technology of tunable diode laser absorption spectroscopy and the technology of micro-electronics, a fiber laser methane sensor based on the microprocessor C8051F410 is given. In this paper, we use the DFB Laser as the light source of the sensor. By tuning temperature and driver current of the DFB laser, we can scan the laser over the methane absorption line, Based on the Beer-Lambert law, through detect the variation of the light power before and after the absorption we realize the methane detection. It makes the real-time and online detection of methane concentration to be true, and it has the advantages just as high accuracy, immunity to other gases , long calibration cycle and so on. The sensor has the function of adaptive gain and self-diagnose. By introducing digital potentiometers, the gain of the photoelectric conversion operational amplifier can be controlled by the microprocessor according to the light power. When the gain and the conversion voltage achieve the set value, then we can consider the sensor in a fault status, and then the software will alarm us to check the status of the probe. So we improved the dependence and the stability of the measured results. At last we give some analysis on the sensor according the field application and according the present working, we have a look of our next work in the distance.

Laser restorative dentistry in children and adolescents.

PubMed

Olivi, G; Genovese, M D

2011-04-01

The idea of substituting a drill with a laser light, has led to its introduction in dentistry. Besides being more accepted to patients, in paediatric dentistry the laser has demonstrated safety compared with rotating instruments. A review of the past 20 years of the dental literature concerning laser use in dentistry, including paediatric dentistry was completed. The findings of that review are presented. The various types of lasers and their uses for caries detection, tooth sealing and caries removal are described. Laser caries detection demonstrated a good reproducibility, reliability and predictability to monitor the caries process over time. Erbium lasers have been found to be efficient for caries removal, tooth cleaning and decontamination. The laser erbium technology represents a safe device to effectively and selectively remove carious tissues from decayed teeth. For children, all the recognized advantages of this technique play a decisive role in the successful day-to-day treatment of dental caries.

Laser Doppler technology applied to atmospheric environmental operating problems

NASA Technical Reports Server (NTRS)

Weaver, E. A.; Bilbro, J. W.; Dunkin, J. A.; Jeffreys, H. B.

1976-01-01

Carbon dioxide laser Doppler ground wind data were very favorably compared with data from standard anemometers. As a result of these measurements, two breadboard systems were developed for taking research data: a continuous wave velocimeter and a pulsed Doppler system. The scanning continuous wave laser Doppler velocimeter developed for detecting, tracking and measuring aircraft wake vortices was successfully tested at an airport where it located vortices to an accuracy of 3 meters at a range of 150 meters. The airborne pulsed laser Doppler system was developed to detect and measure clear air turbulence (CAT). This system was tested aboard an aircraft, but jet stream CAT was not encountered. However, low altitude turbulence in cumulus clouds near a mountain range was detected by the system and encountered by the aircraft at the predicted time.

Project ORION: Orbital Debris Removal Using Ground-Based Sensors and Lasers

NASA Technical Reports Server (NTRS)

Campbell, J. W.

1996-01-01

About 100,000 pieces of 1 to 10-cm debris in low-Earth orbit are too small to track reliably but large enough to cripple or destroy spacecraft. The ORION team studied the feasibility of removing the debris with ground-based laser impulses. Photoablation experiments were surveyed and applied to likely debris materials. Laser intensities needed for debris orbit modification call for pulses on the order of lOkJ or continuous wave lasers on the order of 1 MW. Adaptive optics are necessary to correct for atmospheric turbulence. Wavelength and pulse duration windows were found that limit beam degradation due to nonlinear atmospheric processes. Debris can be detected and located to within about 10 microrads with existing radar and passive optical technology. Fine targeting would be accomplished with laser illumination, which might also be used for detection. Bistatic detection with communications satellites may also be possible. We recommend that existing technology be used to demonstrate the concept at a loss of about $20 million. We calculate that an installation to clear altitudes up to 800 km of 1 to 10-cm debris over 2 years of operation would cost about $80 million. Clearing altitudes up to 1,500 km would take about 3 years and cost about $160 million.

Handheld Lasers Allow Efficient Detection of Fluorescent Marked Organisms in the Field

PubMed Central

Fleischer, Shelby J.; De Moraes, Consuelo M.; Mescher, Mark C.; Tooker, John F.

2015-01-01

Marking organisms with fluorescent dyes and powders is a common technique used in ecological field studies that monitor movement of organisms to examine life history traits, behaviors, and population dynamics. External fluorescent marking is relatively inexpensive and can be readily employed to quickly mark large numbers of individuals; however, the ability to detect marked organisms in the field at night has been hampered by the limited detection distances provided by portable fluorescent ultraviolet lamps. In recent years, significant advances in LED lamp and laser technology have led to development of powerful, low-cost ultraviolet light sources. In this study, we evaluate the potential of these new technologies to improve detection of fluorescent-marked organisms in the field and to create new possibilities for tracking marked organisms in visually challenging environments such as tree canopies and aquatic habitats. Using handheld lasers, we document a method that provides a fivefold increase in detection distance over previously available technologies. This method allows easy scouting of tree canopies (from the ground), as well as shallow aquatic systems. This novel detection method for fluorescent-marked organisms thus promises to significantly enhance the use of fluorescent marking as a non-destructive technique for tracking organisms in natural environments, facilitating field studies that aim to document otherwise inaccessible aspects of the movement, behavior, and population dynamics of study organisms, including species with significant economic impacts or relevance for ecology and human health. PMID:26035303

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.

Research on the trace detection of carbon dioxide gas and modulation parameter optimization based on the TDLAS technology

NASA Astrophysics Data System (ADS)

Zhao, Peng; Tao, Jun; Yu, Chang-rui; Li, Ye

2014-02-01

Based on the technology of tunable diode laser absorption spectroscopy, modulation of the center wavelength of 2004 nm distributed feedback laser diode at a room-temperature, the second harmonic amplitude of CO2 at 2004nm can be obtained. The CO2 concentration can be calculated via the Beer-Lambert law. Sinusoidal modulation parameter is an important factor that affects the sensitivity and accuracy of the system, through the research on the relationship between sinusoidal modulation signal frequency, amplitude and Second harmonic linetype, we finally achieve the detection limit of 10ppm under 12 m optical path.

Quantum Cascade Lasers in Biomedical Infrared Imaging.

PubMed

Bird, Benjamin; Baker, Matthew J

2015-10-01

Technological advances, namely the integration of quantum cascade lasers (QCLs) within an infrared (IR) microscope, are enabling the development of valuable label-free biomedical-imaging tools capable of targeting and detecting salient chemical species within practical clinical timeframes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Reconfigurable Computing As an Enabling Technology for Single-Photon-Counting Laser Altimetry

NASA Technical Reports Server (NTRS)

Powell, Wesley; Hicks, Edward; Pinchinat, Maxime; Dabney, Philip; McGarry, Jan; Murray, Paul

2003-01-01

Single-photon-counting laser altimetry is a new measurement technique offering significant advantages in vertical resolution, reducing instrument size, mass, and power, and reducing laser complexity as compared to analog or threshold detection laser altimetry techniques. However, these improvements come at the cost of a dramatically increased requirement for onboard real-time data processing. Reconfigurable computing has been shown to offer considerable performance advantages in performing this processing. These advantages have been demonstrated on the Multi-KiloHertz Micro-Laser Altimeter (MMLA), an aircraft based single-photon-counting laser altimeter developed by NASA Goddard Space Flight Center with several potential spaceflight applications. This paper describes how reconfigurable computing technology was employed to perform MMLA data processing in real-time under realistic operating constraints, along with the results observed. This paper also expands on these prior results to identify concepts for using reconfigurable computing to enable spaceflight single-photon-counting laser altimeter instruments.

16-element photodiode array for the angular microdeflection detector and for stabilization of a laser radiation direction

NASA Astrophysics Data System (ADS)

Wegrzecki, Maciej; Piotrowski, Tadeusz; Bar, Jan; Dobrowolski, Rafał; Klimov, Andrii; Klos, Helena; Marchewka, Michał; Nieprzecki, Marek; Panas, Andrzej; Prokaryn, Piotr; Seredyński, Bartłomiej; Sierakowski, Andrzej; Słysz, Wojciech; Szmigiel, Dariusz; Zaborowski, Michal

2016-12-01

In this paper, the design and technology of two types of 16-element photodiode arrays is described. The arrays were developed by the ITE and are to be used in detection of microdeflection of laser radiation at the Institute of Metrology and Biomedical Engineering in the Faculty of Mechatronics of Warsaw University of Technology. The electrical and photoelectrical parameters of the arrays are presented.

Study of application and key technology of the high-energy laser weapon in optoelectronic countermeasure

NASA Astrophysics Data System (ADS)

Qu, Zhou; Xing, Hao; Wang, Dawei; Wang, Qiugui

2015-10-01

High-energy Laser weapon is a new-style which is developing rapidly nowadays. It is a one kind of direction energy weapon which can destroy the targets or make them invalid. High-energy Laser weapon has many merits such as concentrated energy, fast transmission, long operating range, satisfied precision, fast shift fire, anti-electromagnetic interference, reusability, cost-effectiveness. High-energy Laser weapon has huge potential for modern warfare since its laser beam launch attack to the target by the speed of light. High-energy Laser weapon can be deployed by multiple methods such as skyborne, carrier borne, vehicle-mounted, foundation, space platform. Besides the connection with command and control system, High-energy Laser weapon is consist of high-energy laser and beam steering. Beam steering is comprised of Large diameter launch system and Precision targeting systems. Meanwhile, beam steering includes the distance measurement of target location, detection system of television and infrared sensor, adaptive optical system of Laser atmospheric distortion correction. The development of laser technology is very fast in recent years. A variety of laser sources have been regarded as the key component in many optoelectronic devices. For directed energy weapon, the progress of laser technology has greatly improved the tactical effectiveness, such as increasing the range and strike precision. At the same time, the modern solid-state laser has become the ideal optical source for optical countermeasure, because it has high photoelectric conversion efficiency and small volume or weight. However, the total performance is limited by the mutual cooperation between different subsystems. The optical countermeasure is a complex technique after many years development. The key factor to evaluate the laser weapon can be formulated as laser energy density to target. This article elaborated the laser device technology of optoelectronic countermeasure and Photoelectric tracking technology. Also the allocation of optoelectronic countermeasure was discussed in this article. At last, this article prospected the future development of high-energy laser.

Laser light scattering instrument advanced technology development

NASA Technical Reports Server (NTRS)

Wallace, J. F.

1993-01-01

The objective of this advanced technology development (ATD) project has been to provide sturdy, miniaturized laser light scattering (LLS) instrumentation for use in microgravity experiments. To do this, we assessed user requirements, explored the capabilities of existing and prospective laser light scattering hardware, and both coordinated and participated in the hardware and software advances needed for a flight hardware instrument. We have successfully breadboarded and evaluated an engineering version of a single-angle glove-box instrument which uses solid state detectors and lasers, along with fiber optics, for beam delivery and detection. Additionally, we have provided the specifications and written verification procedures necessary for procuring a miniature multi-angle LLS instrument which will be used by the flight hardware project which resulted from this work and from this project's interaction with the laser light scattering community.

Understanding Fire Through Improved Technology

NASA Technical Reports Server (NTRS)

2004-01-01

Aztec(TradeMark) is the commercial name for Southwest Sciences laser. The laser has coarse tuning ranges of 10 nanometers (nm) to 30 nm at wavelengths ranging from 630 nm to 2,300 nm, making it the only commercially available external cavity diode laser with wavelengths beyond 1,650 nm. The laser's high-speed tuning in both coarse and fine wavelength regimes allows for increased trace gas detection. With the automated coarse tuning option, the Aztec sweeps through its wavelength range in less than 1 millisecond. While some diode lasers can only detect one type, or species, of a trace gas, the Aztec's broad wavelength tuning provides access to multiple trace gas species. The Aztec has a wide range of applications for both NASA and commercial users, from protecting astronauts in space to improving combustion processes on Earth. It may serve as a new tool for planetary exploration, as it can detect a wide range of multiple gas species in planetary atmospheres. The laser could optically detect gaseous indicators of incipient fires on the International Space Station and Space Shuttle, as well as detect low concentrations of potentially toxic gases in spacecraft crew habitats. The laser could also provide more accurate fire detection in aircraft cargo compartments. Since the Aztec can detect several gases that only evolve during an actual fire, its implementation could reduce the large number of commercial aircraft landings that currently occur due to false alarms. Other applications include environmental and industrial process monitoring.

New semiconductor laser technology for gas sensing applications in the 1650nm range

NASA Astrophysics Data System (ADS)

Morrison, Gordon B.; Sherman, Jes; Estrella, Steven; Moreira, Renan L.; Leisher, Paul O.; Mashanovitch, Milan L.; Stephen, Mark; Numata, Kenji; Wu, Stewart; Riris, Haris

2017-08-01

Atmospheric methane (CH4) is the second most important anthropogenic greenhouse gas with approximately 25 times the radiative forcing of carbon dioxide (CO2) per molecule. CH4 also contributes to pollution in the lower atmosphere through chemical reactions leading to ozone production. Recent developments of LIDAR measurement technology for CH4 have been previously reported by Goddard Space Flight Center (GSFC). In this paper, we report on a novel, high-performance tunable semiconductor laser technology developed by Freedom Photonics for the 1650nm wavelength range operation, and for LIDAR detection of CH4. Devices described are monolithic, with simple control, and compatible with low-cost fabrication techniques. We present 3 different types of tunable lasers implemented for this application.

Detection of biogenic CO production above vascular cell cultures using a near-room-temperature QC-DFB laser

NASA Technical Reports Server (NTRS)

Kosterev, A. A.; Tittel, F. K.; Durante, W.; Allen, M.; Kohler, R.; Gmachl, C.; Capasso, F.; Sivco, D. L.; Cho, A. Y.

2002-01-01

We report the first application of pulsed, near-room-temperature quantum cascade laser technology to the continuous detection of biogenic CO production rates above viable cultures of vascular smooth muscle cells. A computer-controlled sequence of measurements over a 9-h period was obtained, resulting in a minimum detectable CO production of 20 ppb in a 1-m optical path above a standard cell-culture flask. Data-processing procedures for real-time monitoring of both biogenic and ambient atmospheric CO concentrations are described.

Development of Laser-Polarized Noble Gas Magnetic Resonance Imaging (MRI) Technology

NASA Technical Reports Server (NTRS)

Walsworth, Ronald L.

2004-01-01

We are developing technology for laser-polarized noble gas nuclear magnetic resonance (NMR), with the aim of enabling it as a novel biomedical imaging tool for ground-based and eventually space-based application. This emerging multidisciplinary technology enables high-resolution gas-space magnetic resonance imaging (MRI)-e.g., of lung ventilation, perfusion, and gas-exchange. In addition, laser-polarized noble gases (3He and 1BXe) do not require a large magnetic field for sensitive NMR detection, opening the door to practical MRI with novel, open-access magnet designs at very low magnetic fields (and hence in confined spaces). We are pursuing two specific aims in this technology development program. The first aim is to develop an open-access, low-field (less than 0.01 T) instrument for MRI studies of human gas inhalation as a function of subject orientation, and the second aim is to develop functional imaging of the lung using laser-polarized He-3 and Xe-129.

Two Dimensional Positioning and Heading Solution for Flying Vehicles using a Line-Scanning Laser Radar (LADAR)

DTIC Science & Technology

2011-03-24

6 2.4.1 Reference Frames . . . . . . . . . . . . . . . . . 6 2.4.2 Line and Feature Extraction . . . . . . . . . . . 7 2.4.3 SLAM ...Positioning System . . . . . . . . . . . . . . . . . . 1 LADAR Laser Radar . . . . . . . . . . . . . . . . . . . . . . . . . . 1 LiDAR Light Detection and...Ranging . . . . . . . . . . . . . . . . 2 SLAM Simultaneous Localization and Mapping . . . . . . . . . . 2 ANT Advanced Navigation Technology

Analysis of measurements for solid state laser remote lidar system

NASA Technical Reports Server (NTRS)

Amzajerdian, Farzin

1995-01-01

The merits of using lidar systems for remote measurements of various atmospheric processes such as wind, turbulence, moisture, and aerosol concentration are widely recognized. Although the lidar technology has progressed considerably over the past two decades, significant research particularly in the area of solid state lidars remains to be conducted in order to fully exploit this technology. The work performed by the UAH (University of Alabama in Huntsville) personnel under this Delivery Order concentrated on analyses of measurements required in support of solid state laser remote sensing lidar systems which are to be designed, deployed, and used to measure atmospheric processes and constituents. UAH personnel has studied and recommended to NASA/MSFC the requirements of the optical systems needed to characterize the detection devices suitable for solid state wavelengths and to evaluate various heterodyne detection schemes. The 2-micron solid state laser technology was investigated and several preliminary laser designs were developed and their performance for remote sensing of atmospheric winds and clouds from a spaceborne platform were specified. In addition to the laser source and the detector, the other critical technologies necessary for global wind measurements by a spaceborne solid state coherent lidar systems were identified to be developed and demonstrated. As part of this work, an analysis was performed to determine the atmospheric wind velocity estimation accuracy using the line-of-sight measurements of a scanning coherent lidar. Under this delivery order, a computer database of materials related to the theory, development, testing, and operation of lidar systems was developed to serve as a source of information for lidar research and development.

Forty-five degree backscattering-mode nonlinear absorption imaging in turbid media.

PubMed

Cui, Liping; Knox, Wayne H

2010-01-01

Two-color nonlinear absorption imaging has been previously demonstrated with endogenous contrast of hemoglobin and melanin in turbid media using transmission-mode detection and a dual-laser technology approach. For clinical applications, it would be generally preferable to use backscattering mode detection and a simpler single-laser technology. We demonstrate that imaging in backscattering mode in turbid media using nonlinear absorption can be obtained with as little as 1-mW average power per beam with a single laser source. Images have been achieved with a detector receiving backscattered light at a 45-deg angle relative to the incoming beams' direction. We obtain images of capillary tube phantoms with resolution as high as 20 microm and penetration depth up to 0.9 mm for a 300-microm tube at SNR approximately 1 in calibrated scattering solutions. Simulation results of the backscattering and detection process using nonimaging optics are demonstrated. A Monte Carlo-based method shows that the nonlinear signal drops exponentially as the depth increases, which agrees well with our experimental results. Simulation also shows that with our current detection method, only 2% of the signal is typically collected with a 5-mm-radius detector.

A laser communication experiment utilizing the ACT satellite and an airborne laser transceiver

NASA Technical Reports Server (NTRS)

Provencher, Charles E., Jr.; Spence, Rodney L.

1988-01-01

The launch of a laser communication transmitter package into geosynchronous Earth orbit onboard the Advanced Communications Technology Satellite (ACTS) will present an excellent opportunity for the experimental reception of laser communication signals transmitted from a space orbit. The ACTS laser package includes both a heterodyne transmitter (Lincoln Labs design) and a direct detection transmitter (Goddard Space Flight Center design) with both sharing some common optical components. NASA Lewis Research Center's Space Electronics Division is planning to perform a space communication experiment utilizing the GSFC direct detection laser transceiver. The laser receiver will be installed within an aircraft provided with a glass port for the reception of the signal. This paper describes the experiment and the approach to performing such an experiment. Described are the constraints placed on the NASA Lewis experiment by the performance parameters of the laser transmitter and by the ACTS spacecraft operations. The conceptual design of the receiving terminal is given; also included is the anticipated capability of the detector.

Current use and future perspectives of diagnostic and therapeutic lasers in Oral Medicine.

PubMed

Maia, A M A; Barkokebas, A; Pires, A P; Barros, L F; Carvalho, A A T; Leão, J C

2008-10-01

Several diagnostic and therapeutic methods are based on the optical properties of lasers. In therapeutic applications, laser light is absorbed in a specific manner, whereas light is scattered, reflected, or transmitted from different structures. Improvements in laser technology allow new procedures and broaden the scope of applications for both diagnosis and therapy. The focus of laser application in Oral Medicine diagnosis should be early detection of oral squamous cell carcinoma. Novel modalities for the detection of oral malignancy are urgently needed, while others must be continuously improved. Optical coherence tomography and laser-induced fluorescence spectroscopy are currently being studied. In addition to diagnosis of non-malignant lesions, laser therapy has been used based upon the biological reactions and molecular wound healing mechanisms as an alternative for the treatment of a variety of oral soft tissue lesions. The aim of the present article is to review current knowledge and future perspectives of lasers in Oral Medicine.

System and Method for Multi-Wavelength Optical Signal Detection

NASA Technical Reports Server (NTRS)

McGlone, Thomas D. (Inventor)

2017-01-01

The system and method for multi-wavelength optical signal detection enables the detection of optical signal levels significantly below those processed at the discrete circuit level by the use of mixed-signal processing methods implemented with integrated circuit technologies. The present invention is configured to detect and process small signals, which enables the reduction of the optical power required to stimulate detection networks, and lowers the required laser power to make specific measurements. The present invention provides an adaptation of active pixel networks combined with mixed-signal processing methods to provide an integer representation of the received signal as an output. The present invention also provides multi-wavelength laser detection circuits for use in various systems, such as a differential absorption light detection and ranging system.

Laser system development for gravitational-wave interferometry in space

NASA Astrophysics Data System (ADS)

Numata, Kenji; Yu, Anthony W.; Camp, Jordan B.; Krainak, Michael A.

2018-02-01

A highly stable and robust laser system is a key component of the space-based Laser Interferometer Space Antenna (LISA) mission, which is designed to detect gravitational waves from various astronomical sources. The baseline architecture for the LISA laser consists of a low-power, low-noise Nd:YAG non-planar ring oscillator (NPRO) followed by a diode-pumped Yb-fiber amplifier with 2 W output. We are developing such laser system at the NASA Goddard Space Flight Center (GSFC), as well as investigating other laser options. In this paper, we will describe our progress to date and plans to demonstrate a technology readiness level (TRL) 6 LISA laser system.

Analysis of characteristics of Si in blast furnace pig iron and calibration methods in the detection by laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Mei, Yaguang; Cheng, Yuxin; Cheng, Shusen; Hao, Zhongqi; Guo, Lianbo; Li, Xiangyou; Zeng, Xiaoyan

2017-10-01

During the iron-making process in blast furnace, the Si content in liquid pig iron was usually used to evaluate the quality of liquid iron and thermal state of blast furnace. None effective method was found for rapid detecting the Si concentration of liquid iron. Laser-induced breakdown spectroscopy (LIBS) is a kind of atomic emission spectrometry technology based on laser ablation. Its obvious advantage is realizing rapid, in-situ, online analysis of element concentration in open air without sample pretreatment. The characteristics of Si in liquid iron were analyzed from the aspect of thermodynamic theory and metallurgical technology. The relationship between Si and C, Mn, S, P or other alloy elements were revealed based on thermodynamic calculation. Subsequently, LIBS was applied on rapid detection of Si of pig iron in this work. During LIBS detection process, several groups of standard pig iron samples were employed in this work to calibrate the Si content in pig iron. The calibration methods including linear, quadratic and cubic internal standard calibration, multivariate linear calibration and partial least squares (PLS) were compared with each other. It revealed that the PLS improved by normalization was the best calibration method for Si detection by LIBS.

One-kilohertz eye tracker and active intraoperative torsion detection in the NIDEK CXIII and Quest excimer lasers.

PubMed

Waring, George O

2009-10-01

To describe recent technological additions to the NIDEK CXIII and Quest excimer lasers. A summary article with data from previous published studies outlining the benefits of newer technology. The addition of a 1-kHz infrared eye tracker decreased the spread of laser spot placement from a mean of 228.79 microm without a tracker to 38.47 microm with the eye tracker. The addition of real-time torsion error correction produced a statistically significantly lower cylinder dispersion, mean manifest refractive cylinder, and error of angle postoperatively in eyes that underwent LASIK. The incorporation of an ultrahigh speed eye tracker and active cyclotorsion correction surpasses the minimal technology criteria required for accurate wavefront-based ablations. Copyright 2009, SLACK Incorporated.

Geometric identification and damage detection of structural elements by terrestrial laser scanner

NASA Astrophysics Data System (ADS)

Hou, Tsung-Chin; Liu, Yu-Wei; Su, Yu-Min

2016-04-01

In recent years, three-dimensional (3D) terrestrial laser scanning technologies with higher precision and higher capability are developing rapidly. The growing maturity of laser scanning has gradually approached the required precision as those have been provided by traditional structural monitoring technologies. Together with widely available fast computation for massive point cloud data processing, 3D laser scanning can serve as an efficient structural monitoring alternative for civil engineering communities. Currently most research efforts have focused on integrating/calculating the measured multi-station point cloud data, as well as modeling/establishing the 3D meshes of the scanned objects. Very little attention has been spent on extracting the information related to health conditions and mechanical states of structures. In this study, an automated numerical approach that integrates various existing algorithms for geometric identification and damage detection of structural elements were established. Specifically, adaptive meshes were employed for classifying the point cloud data of the structural elements, and detecting the associated damages from the calculated eigenvalues in each area of the structural element. Furthermore, kd-tree was used to enhance the searching efficiency of plane fitting which were later used for identifying the boundaries of structural elements. The results of geometric identification were compared with M3C2 algorithm provided by CloudCompare, as well as validated by LVDT measurements of full-scale reinforced concrete beams tested in laboratory. It shows that 3D laser scanning, through the established processing approaches of the point cloud data, can offer a rapid, nondestructive, remote, and accurate solution for geometric identification and damage detection of structural elements.

Emerging technologies in Si active photonics

NASA Astrophysics Data System (ADS)

Wang, Xiaoxin; Liu, Jifeng

2018-06-01

Silicon photonics for synergistic electronic–photonic integration has achieved remarkable progress in the past two decades. Active photonic devices, including lasers, modulators, and photodetectors, are the key challenges for Si photonics to meet the requirement of high bandwidth and low power consumption in photonic datalinks. Here we review recent efforts and progress in high-performance active photonic devices on Si, focusing on emerging technologies beyond conventional foundry-ready Si photonics devices. For emerging laser sources, we will discuss recent progress towards efficient monolithic Ge lasers, mid-infrared GeSn lasers, and high-performance InAs quantum dot lasers on Si for data center applications in the near future. We will then review novel modulator materials and devices beyond the free carrier plasma dispersion effect in Si, including GeSi and graphene electro-absorption modulators and plasmonic-organic electro-optical modulators, to achieve ultralow power and high speed modulation. Finally, we discuss emerging photodetectors beyond epitaxial Ge p–i–n photodiodes, including GeSn mid-infrared photodetectors, all-Si plasmonic Schottky infrared photodetectors, and Si quanta image sensors for non-avalanche, low noise single photon detection and photon counting. These emerging technologies, though still under development, could make a significant impact on the future of large-scale electronicSilicon photonics for synergistic electronic-photonic integration has achieved remarkable progress in the past two decades. Active photonic devices, including lasers, modulators, and photodetectors, are the key challenges for Si photonics to meet the requirement of high bandwidth and low power consumption in photonic datalinks. Here we review recent efforts and progress in high-performance active photonic devices on Si, focusing on emerging technologies beyond conventional foundry-ready Si photonics devices. For emerging laser sources, we will discuss recent progress towards efficient monolithic Ge lasers, mid-infrared GeSn lasers, and high-performance InAs quantum dot lasers on Si for data center applications in the near future. We will then review novel modulator materials and devices beyond the free carrier plasma dispersion effect in Si, including GeSi and graphene electro-absorption modulators and plasmonic-organic electro–optical modulators, to achieve ultralow power and high speed modulation. Finally, we discuss emerging photodetectors beyond epitaxial Ge p–i–n photodiodes, including GeSn mid-infrared photodetectors, all-Si plasmonic Schottky infrared photodetectors, and Si quanta image sensors for non-avalanche, low noise single photon detection and photon counting. These emerging technologies, though still under development, could make a significant impact on the future of large-scale electronic–photonic integration with performance inaccessible from conventional Si photonics technologies-photonic integration with performance inaccessible from conventional Si photonics technologies.

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.

A REMOTE SENSING AND GIS-ENABLED HIGHWAY ASSET MANAGEMENT SYSTEM PHASE 2

DOT National Transportation Integrated Search

2018-02-02

The objective of this project is to validate the use of commercial remote sensing and spatial information (CRS&SI) technologies, including emerging 3D line laser imaging technology, mobile light detection and ranging (LiDAR), image processing algorit...

Fluorescence detection system for microfluidic droplets

NASA Astrophysics Data System (ADS)

Chen, Binyu; Han, Xiaoming; Su, Zhen; Liu, Quanjun

2018-05-01

In microfluidic detection technology, because of the universality of optical methods in laboratory, optical detection is an attractive solution for microfluidic chip laboratory equipment. In addition, the equipment with high stability and low cost can be realized by integrating appropriate optical detection technology on the chip. This paper reports a detection system for microfluidic droplets. Photomultiplier tubes (PMT) is used as a detection device to improve the sensitivity of detection. This system improves the signal to noise ratio by software filtering and spatial filter. The fluorescence intensity is proportional to the concentration of the fluorescence and intensity of the laser. The fluorescence micro droplets of different concentrations can be distinguished by this system.

Wide-field airborne laser diode array illuminator: demonstration results

NASA Astrophysics Data System (ADS)

Suiter, H. R.; Holloway, J. H., Jr.; Tinsley, K. R.; Pham, C. N.; Kloess, E. C., III; Witherspoon, N. H.; Stetson, S.; Crosby, F.; Nevis, A.; McCarley, K. A.; Seales, T. C.

2005-06-01

The Airborne Littoral Reconnaissance Technology (ALRT) program has successfully demonstrated the Wide-Field Airborne Laser Diode Array Illuminator (ALDAI-W). This illuminator is designed to illuminate a large area from the air with limited power, weight, and volume. A detection system, of which the ALDAI-W is a central portion, is capable of detecting surface-laid minefields in absolute darkness, extending the allowed mission times to night operations. This will be an overview report, giving processing results and suggested paths for additional development.

Standoff detection of explosive molecules using nanosecond gated Raman spectroscopy

NASA Astrophysics Data System (ADS)

Chung, Jin Hyuk; Cho, Soo Gyeong

2013-06-01

Recently, improvised explosive device (IED) has been a serious threat for many countries. One of the approaches to alleviate this threat is standoff detection of explosive molecules used in IEDs. Raman spectroscopy is a prospective method among many technologies under research to achieve this goal. It provides unique information of the target materials, through which the ingredients used in IEDs can be analyzed and identified. The main problem of standoff Raman spectroscopic detection is the large background noise hindering weak Raman signals from the target samples. Typical background noise comes from both ambient fluorescent lights indoor and sunlight outdoor whose intensities are usually much larger than that of Raman scattering from the sample. Under the proper condition using pulse laser and ICCD camera with nanosecond pulse width and gating technology, we succeed to separate and remove these background noises from Raman signals. For this experiment, we build an optical system for standoff detection of explosive molecules. We use 532 nm, 10 Hz, Q-switching Nd:YAG laser as light source, and ICCD camera triggered by laser Qswitching time with proper gate delay regarding the flight time of Raman from target materials. Our detection system is successfully applied to detect and identify more than 20 ingredients of IEDs including TNT, RDX, and HMX which are located 10 to 54 meters away from the system.

Laser Welding Process Monitoring Systems: Advanced Signal Analysis for Quality Assurance

NASA Astrophysics Data System (ADS)

D'Angelo, Giuseppe

Laser material processing today is widely used in industry. Especially laser welding became one of the key-technologies, e. g., for the automotive sector. This is due to the improvement and development of new laser sources and the increasing knowledge gained at countless scientific research projects. Nevertheless, it is still not possible to use the full potential of this technology. Therefore, the introduction and application of quality-assuring systems is required. For a long time, the statement "the best sensor is no sensor" was often heard. Today, a change of paradigm can be observed. On the one hand, ISO 9000 and other by law enforced regulations have led to the understanding that quality monitoring is an essential tool in modern manufacturing and necessary in order to keep production results in deterministic boundaries. On the other hand, rising quality requirements not only set higher and higher requirements for the process technology but also demand qualityassurance measures which ensure the reliable recognition of process faults. As a result, there is a need for reliable online detection and correction of welding faults by means of an in-process monitoring. The chapter describes an advanced signals analysis technique to extract information from signals detected, during the laser welding process, by optical sensors. The technique is based on the method of reassignment which was first applied to the spectrogram by Kodera, Gendrin and de Villedary22,23 and later generalized to any bilinear time-frequency representation by Auger and Flandrin.24 Key to the method is a nonlinear convolution where the value of the convolution is not placed at the center of the convolution kernel but rather reassigned to the center of mass of the function within the kernel. The resulting reassigned representation yields significantly improved components localization. We compare the proposed time-frequency distributions by analyzing signals detected during the laser welding of tailored blanks, demonstrating the advantages of the reassigned representation, giving practical applicability to the proposed method.

Laser Truss Sensor for Segmented Telescope Phasing

NASA Technical Reports Server (NTRS)

Liu, Duncan T.; Lay, Oliver P.; Azizi, Alireza; Erlig, Herman; Dorsky, Leonard I.; Asbury, Cheryl G.; Zhao, Feng

2011-01-01

A paper describes the laser truss sensor (LTS) for detecting piston motion between two adjacent telescope segment edges. LTS is formed by two point-to-point laser metrology gauges in a crossed geometry. A high-resolution (<30 nm) LTS can be implemented with existing laser metrology gauges. The distance change between the reference plane and the target plane is measured as a function of the phase change between the reference and target beams. To ease the bandwidth requirements for phase detection electronics (or phase meter), homodyne or heterodyne detection techniques have been used. The phase of the target beam also changes with the refractive index of air, which changes with the air pressure, temperature, and humidity. This error can be minimized by enclosing the metrology beams in baffles. For longer-term (weeks) tracking at the micron level accuracy, the same gauge can be operated in the absolute metrology mode with an accuracy of microns; to implement absolute metrology, two laser frequencies will be used on the same gauge. Absolute metrology using heterodyne laser gauges is a demonstrated technology. Complexity of laser source fiber distribution can be optimized using the range-gated metrology (RGM) approach.

In situ detection of tropospheric OH, HO2, NO2, and NO by laser-induced fluorescence in detection chambers at reduced pressures

NASA Technical Reports Server (NTRS)

Brune, William H.

1993-01-01

This report is a brief summary of the status of work on the grant entitled 'In situ detection of tropospheric OH, HO2, NO2, and NO by laser induced fluorescence in detection chambers at low pressures.' The basic instrument characteristics have been established, and have been reported in a manuscript, included as an appendix to this report, that has been accepted by the Journal of Geophysical Research. Currently, two efforts are under way. First, instrument tests and calibrations are continuing. These efforts include field measurements and an informal inter comparison in Colorado last August and September. Second, new technologies in lasers and detectors are being implemented to make the instrument smaller, lighter, and more energy efficient. Such instrument modifications are essential for measurements from aircraft, high scaffolding in forests, and ships.

Precision requirements and innovative manufacturing for ultrahigh precision laser interferometry of gravitational-wave astronomy

NASA Astrophysics Data System (ADS)

Ni, Wei-Tou; Han, Sen; Jin, Tao

2016-11-01

With the LIGO announcement of the first direct detection of gravitational waves (GWs), the GW Astronomy was formally ushered into our age. After one-hundred years of theoretical investigation and fifty years of experimental endeavor, this is a historical landmark not just for physics and astronomy, but also for industry and manufacturing. The challenge and opportunity for industry is precision and innovative manufacturing in large size - production of large and homogeneous optical components, optical diagnosis of large components, high reflectance dielectric coating on large mirrors, manufacturing of components for ultrahigh vacuum of large volume, manufacturing of high attenuating vibration isolation system, production of high-power high-stability single-frequency lasers, production of high-resolution positioning systems etc. In this talk, we address the requirements and methods to satisfy these requirements. Optical diagnosis of large optical components requires large phase-shifting interferometer; the 1.06 μm Phase Shifting Interferometer for testing LIGO optics and the recently built 24" phase-shifting Interferometer in Chengdu, China are examples. High quality mirrors are crucial for laser interferometric GW detection, so as for ring laser gyroscope, high precision laser stabilization via optical cavities, quantum optomechanics, cavity quantum electrodynamics and vacuum birefringence measurement. There are stringent requirements on the substrate materials and coating methods. For cryogenic GW interferometer, appropriate coating on sapphire or silicon are required for good thermal and homogeneity properties. Large ultrahigh vacuum components and high attenuating vibration system together with an efficient metrology system are required and will be addressed. For space interferometry, drag-free technology and weak-light manipulation technology are must. Drag-free technology is well-developed. Weak-light phase locking is demonstrated in the laboratories while weak-light manipulation technology still needs developments.

Detection of errant laser beams

NASA Astrophysics Data System (ADS)

Taylor, Arthur F. D. S.; Edwards, Stanley A.; Barrett, J. A.; Bandle, Anthony M.

1990-10-01

The new generation of automated laser machine tools poses problems for those responsible for setting safety standards. While traditional safeguarding will frustrate full exploitation of this hybrid technology, wholesale abandonment of effective containment in favour of safety monitoring and control systems is unlikely to be acceptable. Long term, quantitative risk assessment will resolve this dilemma. Short term, guide lines will have to be derived from practical considerations of the laser facility design, materials, primary safety devices and procedures. Earlier risk assessments are reviewed relative to the emerging perspective of high average power laser installations. Aspects of extended beam delivery systems and equipment utilization and maintenance are examined to assess possible interaction with operational safety and in particular the potential to adversely influence errant laser beam occurrances (ELBO). To satisfy international safety standards for a laser enclosure which offers flexibility and is cost effective a detection system is described which continuously surveys the inside of the enclosure. Extensive trials have been carried out with high average power lasers (up to 10kW) where a range of engineering materials has been exposed to a laser beam. It is shown that the ratio of detection and shut down time to the burn through time can be an acceptable risk and thus indicate which materials will prove adequate.

Online detecting system of roller wear based on laser-linear array CCD technology

NASA Astrophysics Data System (ADS)

Guo, Yuan

2010-10-01

Roller is an important metallurgy tool in the rolling mill. And the surface of a roller affects the quantity of the rolling product directly. After using a period of time, roller must be repaired or replaced. Examining the profile of a working roller between the intervals of rolling is called online detecting for roller wear. The study of online detecting roller wear is very important for selecting the grinding time in reason, reducing the exchanging times of rollers, improving the quality of the product and realizing online grinding rollers. By applying the laser-linear array CCD detective technology, a method for online non-touch detecting roller wear was brought forward. The principle, composition and the operation process of the linear array CCD detecting system were expatiated. And an error compensation algorithm is exactly calculated to offset the shift of the roller axis in this measurement system. So the stability and the accuracy were improved remarkably. The experiment proves that the accuracy of the detecting system reaches to the demand of practical production process. It can provide a new method of high speed and high accuracy online detecting for roller wear.

Enhancement of laser-induced breakdown spectroscopy (LIBS) Detection limit using a low-pressure and short-pulse laser-induced plasma process.

PubMed

Wang, Zhen Zhen; Deguchi, Yoshihiro; Kuwahara, Masakazu; Yan, Jun Jie; Liu, Ji Ping

2013-11-01

Laser-induced breakdown spectroscopy (LIBS) technology is an appealing technique compared with many other types of elemental analysis because of the fast response, high sensitivity, real-time, and noncontact features. One of the challenging targets of LIBS is the enhancement of the detection limit. In this study, the detection limit of gas-phase LIBS analysis has been improved by controlling the pressure and laser pulse width. In order to verify this method, low-pressure gas plasma was induced using nanosecond and picosecond lasers. The method was applied to the detection of Hg. The emission intensity ratio of the Hg atom to NO (IHg/INO) was analyzed to evaluate the LIBS detection limit because the NO emission (interference signal) was formed during the plasma generation and cooling process of N2 and O2 in the air. It was demonstrated that the enhancement of IHg/INO arose by decreasing the pressure to a few kilopascals, and the IHg/INO of the picosecond breakdown was always much higher than that of the nanosecond breakdown at low buffer gas pressure. Enhancement of IHg/INO increased more than 10 times at 700 Pa using picosecond laser with 35 ps pulse width. The detection limit was enhanced to 0.03 ppm (parts per million). We also saw that the spectra from the center and edge parts of plasma showed different features. Comparing the central spectra with the edge spectra, IHg/INO of the edge spectra was higher than that of the central spectra using the picosecond laser breakdown process.

Ground-based deep-space LADAR for satellite detection: A parametric study

NASA Astrophysics Data System (ADS)

Davey, Kevin F.

1989-12-01

The minimum performance requirements are determined of a ground based infrared LADAR designed to detect deep space satellites, and a candidate sensor design is presented based on current technology. The research examines LADAR techniques and detection methods to determine the optimum LADAR configuration, and then assesses the effects of atmospheric transmission, background radiance, and turbulence across the infrared region to find the optimum laser wavelengths. Diffraction theory is then used in a parametric analysis of the transmitted laser beam and received signal, using a Cassegrainian telescope design and heterodyne detection. The effects of beam truncation and obscuration, heterodyne misalignment, off-boresight detection, and image-pixel geometry are also included in the analysis. The derived equations are then used to assess the feasibility of several candidate designs under a wide range of detection conditions including daylight operation through cirrus. The results show that successful detection is theoretically possible under most conditions by transmitting a high power frequency modulated pulse train from an isotopic 13CO2 laser radiating at 11.17 micrometers, and utilizing post-detection integration and pulse compression techniques.

Testing technology

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

Not Available

1993-10-01

This bulletin from Sandia National Laboratories presents current research highlights in testing technology. Ion microscopy offers new nondestructive testing technique that detects high resolution invisible defects. An inexpensive thin-film gauge checks detonators on centrifuge. Laser trackers ride the range and track helicopters at low-level flights that could not be detected by radar. Radiation transport software predicts electron/photon effects via cascade simulation. Acoustic research in noise abatement will lead to quieter travelling for Bay Area Rapid Transport (BART) commuters.

Comparison of cap lamp and laser illumination for detecting visual escape cues in smoke

PubMed Central

Lutz, T.J.; Sammarco, J.J.; Srednicki, J.R.; Gallagher, S.

2015-01-01

The Illuminating Engineering Society of North America reports that an underground mine is the most difficult environment to illuminate (Rea, 2000). Researchers at the U.S. National Institute for Occupational Safety and Health (NIOSH) Office of Mine Safety and Health Research (OMSHR) are conducting ongoing studies designed to explore different lighting technologies for improving mine safety. Underground miners use different visual cues to escape from a smoke-filled environment. Primary and secondary escapeways are marked with reflective ceiling tags of various colors. Miners also look for mine rail tracks. The main objective of this paper is to compare different lighting types and ceiling tag colors to differentiate what works best in a smoke-filled environment. Various cap lamps (LED and incandescent) and lasers (red, blue, green) were compared to see which options resulted in the longest detection distances for red, green and blue reflective markers and a section of mine rail track. All targets advanced toward the human subject inside of a smoke-filled room to simulate the subject walking in a mine environment. Detection distances were recorded and analyzed to find the best cap lamp, laser color and target color in a smoke environment. Results show that cap lamp, laser color and target color do make a difference in detection distances and are perceived differently based on subject age. Cap lamps were superior to lasers in all circumstances of ceiling tag detection, with the exception of the green laser. The incandescent cap lamp worked best in the simulated smoke compared to the LED cap lamps. The green laser was the best color for detecting the tags and track compared to the red and blue lasers. The green tags were the easiest color to detect on the ceiling. On average, the track was easier for the subjects to detect than the ceiling tags. PMID:26236146

Comparison of cap lamp and laser illumination for detecting visual escape cues in smoke.

PubMed

Lutz, T J; Sammarco, J J; Srednicki, J R; Gallagher, S

The Illuminating Engineering Society of North America reports that an underground mine is the most difficult environment to illuminate (Rea, 2000). Researchers at the U.S. National Institute for Occupational Safety and Health (NIOSH) Office of Mine Safety and Health Research (OMSHR) are conducting ongoing studies designed to explore different lighting technologies for improving mine safety. Underground miners use different visual cues to escape from a smoke-filled environment. Primary and secondary escapeways are marked with reflective ceiling tags of various colors. Miners also look for mine rail tracks. The main objective of this paper is to compare different lighting types and ceiling tag colors to differentiate what works best in a smoke-filled environment. Various cap lamps (LED and incandescent) and lasers (red, blue, green) were compared to see which options resulted in the longest detection distances for red, green and blue reflective markers and a section of mine rail track. All targets advanced toward the human subject inside of a smoke-filled room to simulate the subject walking in a mine environment. Detection distances were recorded and analyzed to find the best cap lamp, laser color and target color in a smoke environment. Results show that cap lamp, laser color and target color do make a difference in detection distances and are perceived differently based on subject age. Cap lamps were superior to lasers in all circumstances of ceiling tag detection, with the exception of the green laser. The incandescent cap lamp worked best in the simulated smoke compared to the LED cap lamps. The green laser was the best color for detecting the tags and track compared to the red and blue lasers. The green tags were the easiest color to detect on the ceiling. On average, the track was easier for the subjects to detect than the ceiling tags.

Analysis of Technology for Compact Coherent Lidar

NASA Technical Reports Server (NTRS)

Amzajerdian, Farzin

1997-01-01

In view of the recent advances in the area of solid state and semiconductor lasers has created new possibilities for the development of compact and reliable coherent lidars for a wide range of applications. These applications include: Automated Rendezvous and Capture, wind shear and clear air turbulence detection, aircraft wake vortex detection, and automobile collision avoidance. The work performed by the UAH personnel under this Delivery Order, concentrated on design and analyses of a compact coherent lidar system capable of measuring range and velocity of hard targets, and providing air mass velocity data. The following is the scope of this work. a. Investigate various laser sources and optical signal detection configurations in support of a compact and lightweight coherent laser radar to be developed for precision range and velocity measurements of hard and fuzzy targets. Through interaction with MSFC engineers, the most suitable laser source and signal detection technique that can provide a reliable compact and lightweight laser radar design will be selected. b. Analyze and specify the coherent laser radar system configuration and assist with its optical and electronic design efforts. Develop a system design including its optical layout design. Specify all optical components and provide the general requirements of the electronic subsystems including laser beam modulator and demodulator drivers, detector electronic interface, and the signal processor. c. Perform a thorough performance analysis to predict the system measurement range and accuracy. This analysis will utilize various coherent laser radar sensitivity formulations and different target models.

Single photon ranging system using two wavelengths laser and analysis of precision

NASA Astrophysics Data System (ADS)

Chen, Yunfei; He, Weiji; Miao, Zhuang; Gu, Guohua; Chen, Qian

2013-09-01

The laser ranging system based on time correlation single photon counting technology and single photon detector has the feature of high precision and low emergent energy etc. In this paper, we established a single photon laser ranging system that use the supercontinuum laser as light source, and two wavelengths (532nm and 830nm) of echo signal as the stop signal. We propose a new method that is capable to improve the single photon ranging system performance. The method is implemented by using two single-photon detectors to receive respectively the two different wavelength signals at the same time. We extracted the firings of the two detectors triggered by the same laser pulse at the same time and then took mean time of the two firings as the combined detection time-of-flight. The detection by two channels using two wavelengths will effectively improve the detection precision and decrease the false alarm probability. Finally, an experimental single photon ranging system was established. Through a lot of experiments, we got the system precision using both single and two wavelengths and verified the effectiveness of the method.

A concept for early cancer detection and therapy

NASA Astrophysics Data System (ADS)

Waynant, Ronald W.; Ilev, Ilko K.; Mitra, Kunal

2003-06-01

Early detection and treatment of breast cancer is least costly in terms of dollars, morbidity and mortality. With new early detection x-ray technology, tumors can be found, diagnosed and treated at a much smaller size than is currently possible. This paper proposes the development of a high resolution, high quality imaging system. It is a laser-driven x-ray system with time-gated detection that removes scattering noise in the image and produces resolution on the order of 10 μm. This higher resolution and higher image quality will enable the detection of one or two millimeter tumors hopefully detecting them before metastasis. We also propose that tumor detection should be followed by an immediate needle-directed, optical fiber biopsy to instantly determine if cancer is present and, if present, the tumor should immediately be given a lethal treatment of laser or x-radiation through the same needle using fiber optics or hollow waveguides. This technology will help prevent multiple interventions resulting in both the lowest overall cost and a more efficacious therapy. The approach can be stopped at the first negative (benign) indication and will help forestall repeated examination as well as reduce patient anxiety.

Tracing Acetylene Dissolved in Transformer Oil by Tunable Diode Laser Absorption Spectrum.

PubMed

Ma, Guo-Ming; Zhao, Shu-Jing; Jiang, Jun; Song, Hong-Tu; Li, Cheng-Rong; Luo, Ying-Ting; Wu, Hao

2017-11-02

Dissolved gas analysis (DGA) is widely used in monitoring and diagnosing of power transformer, since the insulation material in the power transformer decomposes gases under abnormal operation condition. Among the gases, acetylene, as a symbol of low energy spark discharge and high energy electrical faults (arc discharge) of power transformer, is an important monitoring parameter. The current gas detection method used by the online DGA equipment suffers from problems such as cross sensitivity, electromagnetic compatibility and reliability. In this paper, an optical gas detection system based on TDLAS technology is proposed to detect acetylene dissolved in transformer oil. We selected a 1530.370 nm laser in the near infrared wavelength range to correspond to the absorption peak of acetylene, while using the wavelength modulation strategy and Herriott cell to improve the detection precision. Results show that the limit of detection reaches 0.49 ppm. The detection system responds quickly to changes of gas concentration and is easily to maintenance while has no electromagnetic interference, cross-sensitivity, or carrier gas. In addition, a complete detection process of the system takes only 8 minutes, implying a practical prospect of online monitoring technology.

Precise measurement of ultra-narrow laser linewidths using the strong coherent envelope

NASA Astrophysics Data System (ADS)

Huang, Shihong; Zhu, Tao; Liu, Min; Huang, Wei

2017-02-01

Laser linewidth narrowing down to kHz or even Hz is an important topic in areas like clock synchronization technology, laser radars, quantum optics, and high-precision detection. Conventional decoherence measurement methods like delayed self-heterodyne/homodyne interferometry cannot measure such narrow linewidths accurately. This is because a broadening of the Gaussian spectrum, which hides the laser’s intrinsic Lorentzian linewidth, cannot be avoided. Here, we introduce a new method using the strong coherent envelope to characterize the laser’s intrinsic linewidth through self-coherent detection. This method can eliminate the effect of the broadened Gaussian spectrum induced by the 1/f frequency noise. We analyze, in detail, the relationship between intrinsic laser linewidth, contrast difference with the second peak and the second trough (CDSPST) of the strong coherent envelope, and the length of the delaying fiber. The correct length for the delaying fiber can be chosen by combining the estimated laser linewidth (Δfest) with a specific CDSPST (ΔS) to obtain the accurate laser linewidth (Δf). Our results indicate that this method can be used as an accurate detection tool for measurements of narrow or super-narrow linewidths.

On the detectability of the Lense-Thirring field from rotating laboratory masses using ring laser gyroscope interferometers

NASA Astrophysics Data System (ADS)

Stedman, G. E.; Schreiber, K. U.; Bilger, H. R.

2003-07-01

The possibility of detecting the Lense-Thirring field generated by the rotating earth (also rotating laboratory masses) is reassessed in view of recent dramatic advances in the technology of ring laser gyroscopes. This possibility is very much less remote than it was a decade ago. The effect may contribute significantly to the Sagnac frequency of planned instruments. Its discrimination and detection will require an improved metrology, linking the ring to the celestial reference frame, and a fuller study of dispersion- and backscatter-induced frequency pulling. Both these requirements have been the subject of recent major progress, and our goal looks feasible.

Simulation study and guidelines to generate Laser-induced Surface Acoustic Waves for human skin feature detection

NASA Astrophysics Data System (ADS)

Li, Tingting; Fu, Xing; Chen, Kun; Dorantes-Gonzalez, Dante J.; Li, Yanning; Wu, Sen; Hu, Xiaotang

2015-12-01

Despite the seriously increasing number of people contracting skin cancer every year, limited attention has been given to the investigation of human skin tissues. To this regard, Laser-induced Surface Acoustic Wave (LSAW) technology, with its accurate, non-invasive and rapid testing characteristics, has recently shown promising results in biological and biomedical tissues. In order to improve the measurement accuracy and efficiency of detecting important features in highly opaque and soft surfaces such as human skin, this paper identifies the most important parameters of a pulse laser source, as well as provides practical guidelines to recommended proper ranges to generate Surface Acoustic Waves (SAWs) for characterization purposes. Considering that melanoma is a serious type of skin cancer, we conducted a finite element simulation-based research on the generation and propagation of surface waves in human skin containing a melanoma-like feature, determine best pulse laser parameter ranges of variation, simulation mesh size and time step, working bandwidth, and minimal size of detectable melanoma.

Optofluidic lasers and their applications in bioanalysis (Conference Presentation)

NASA Astrophysics Data System (ADS)

Fan, Xudong

2016-03-01

The optofluidic laser is an emerging technology that integrates microfluidics, miniaturized laser cavity, and laser gain medium in liquid. It is unique due to its biocompatibility, thus can be used for unconventional bioanalysis, in which biointeraction or process takes place within the optical cavity mode volume. Rather than using fluorescence, the optofluidic laser based detection employs laser emission, i.e., stimulated emission, as the sensing signal, which takes advantage of optical amplification provided by the laser cavity to achieve much higher sensitivity. In this presentation, I will first introduce the concept of optofluidic laser based bioanalysis. Then I will discuss each of the three components (cavity, gain medium, and fluidics) of the optofluidic laser and describe how to use the optofluidic laser in bioanalysis at the molecular, cellular, and tissue level. Finally, I will discuss future research and application directions.

Laser Sources for Generation of Ultrasound

NASA Technical Reports Server (NTRS)

Wagner, James W.

1996-01-01

Two laser systems have been built and used to demonstrate enhancements beyond current technology used for laser-based generation and detection of ultrasound. The first system consisted of ten Nd:YAG laser cavities coupled electronically and optically to permit sequential bursts of up to ten laser pulses directed either at a single point or configured into a phased array of sources. Significant enhancements in overall signal-to-noise ratio for laser ultrasound incorporating this new source system was demonstrated, using it first as a source of narrowband ultrasound and secondly as a phased array source producing large enhanced signal displacements. A second laser system was implemented using ultra fast optical pulses from a Ti:Sapphire laser to study a new method for making laser generated ultrasonic measurements of thin films with thicknesses on the order of hundreds of angstroms. Work by prior investigators showed that such measurements could be made based upon fluctuations in the reflectivity of thin films when they are stressed by an arriving elastic pulse. Research performed using equipment purchased under this program showed that a pulsed interferometric system could be used as well as a piezoreflective detection system to measure pulse arrivals even in thin films with very low piezoreflective coefficients.

Research of cartographer laser SLAM algorithm

NASA Astrophysics Data System (ADS)

Xu, Bo; Liu, Zhengjun; Fu, Yiran; Zhang, Changsai

2017-11-01

As the indoor is a relatively closed and small space, total station, GPS, close-range photogrammetry technology is difficult to achieve fast and accurate indoor three-dimensional space reconstruction task. LIDAR SLAM technology does not rely on the external environment a priori knowledge, only use their own portable lidar, IMU, odometer and other sensors to establish an independent environment map, a good solution to this problem. This paper analyzes the Google Cartographer laser SLAM algorithm from the point cloud matching and closed loop detection. Finally, the algorithm is presented in the 3D visualization tool RViz from the data acquisition and processing to create the environment map, complete the SLAM technology and realize the process of indoor threedimensional space reconstruction

Latest developments for low-power infrared laser-based trace gas sensors for sensor networks

NASA Astrophysics Data System (ADS)

So, Stephen; Thomazy, David; Wang, Wen; Marchat, Oscar; Wysocki, Gerard

2011-09-01

Academic and industrial researchers require ultra-low power, compact laser based trace-gas sensor systems for the most demanding environmental and space-borne applications. Here the latest results from research projects addressing these applications will be discussed: 1) an ultra-compact CO2 sensor based on a continuous wave quantum cascade laser, 2) an ultra-sensitive Faraday rotation spectrometer for O2 detection, 3) a fully ruggedized compact and low-power laser spectrometer, and 4) a novel non-paraxial nonthin multipass cell. Preliminary tests and projection for performance of future sensors based on this technology is presented.

[System design of open-path natural gas leakage detection based on Fresnel lens].

PubMed

Xia, Hui; Liu, Wen-Qing; Zhang, Yu-Jun; Kan, Rui-Feng; Cui, Yi-Ben; Wang, Min; He, Ying; Cui, Xiao-Juan; Ruan, Jun; Geng, Hui

2009-03-01

Based on the technology of tunable diode laser absorption spectroscopy (TDLAS) in conjunction with second harmonic wave detection, a long open-path TDLAS system using a 1.65 microm InGaAsP distributed feedback laser was developed, which is used for detecting pipeline leakage. In this system, a high cost performance Fresnel lens is used as the receiving optical system, which receives the laser-beam reflected by a solid corner cube reflector, and focuses the receiving laser-beam to the InGaAs detector. At the same time, the influences of the concentration to the fluctuation of light intensity were taken into account in the process of measurement, and were eliminated by the method of normalized light intensity. As a result, the measurement error caused by the fluctuation of light intensity was made less than 1%. The experiment of natural gas leakage detection was simulated, and the detection sensitivity is 0.1 x 10(-6) (ratio by volume) with a total path of 320 m. According to the receiving light efficiency of the optical system and the detectable minimum light intensity of the detector, the detectable maximal optical path of the system was counted to be 2 000 m. The results of experiment show that it is a feasible design to use the Fresnel lens as the receiving optical system and can satisfy the demand of the leakage detection of natural gas.

Research on the system scheme and experiment for the active laser polarization imaging

NASA Astrophysics Data System (ADS)

Fu, Qiang; Duan, Jin; Zhao, Rui; Li, Zheng; Zhang, Su; Zhan, Juntong; Zhu, Yong; Jiang, Hui-Lin

2015-10-01

The polarization imaging detection technology increased the polarization information on the basis of the intensity imaging, which is extensive application in the military and civil and other fields. The research present and development trend of polarization imaging detection technology was introduce, the system scheme of the active polarization imaging detection was put forward, and the key technologies such as the polarization information detection, optical system design, polarization radiation calibration and image fusion approach was analyzed. On this basis, detection system by existing equipment of laboratory was set up, and on the different materials such as wood, metal, plastic and goal was detected by polarization imaging to realize the active polarization imaging detection. The results show that image contrast of the metal and man-made objects is higher, the polarization effect is better, which provided the basis on the better performance of the polarization imaging instruments.

Application of 3D Laser Scanning Technology in Inspection and Dynamic Reserves Detection of Open-Pit Mine

NASA Astrophysics Data System (ADS)

Hu, Zhumin; Wei, Shiyu; Jiang, Jun

2017-10-01

The traditional open-pit mine mining rights verification and dynamic reserve detection means rely on the total station and RTK to collect the results of the turning point coordinates of mining surface contours. It resulted in obtaining the results of low precision and large error in the means that is limited by the traditional measurement equipment accuracy and measurement methods. The three-dimensional scanning technology can obtain the three-dimensional coordinate data of the surface of the measured object in a large area at high resolution. This paper expounds the commonly used application of 3D scanning technology in the inspection and dynamic reserve detection of open mine mining rights.

The possibility of using remote sensing technology of lidar for monitoring ecosystem health by detecting habitat condition

NASA Astrophysics Data System (ADS)

Huseyinoglu, M. F.; Salaeva, Z.; Secgin, A.; Allakhverdiev, S. R.; Allakhverdiev, K. R.

2012-01-01

Since the emergence of laser and henceforth laser remote sensing in the 1960's, lidar (light detecting and ranging) technology has became a significant tool for the detection of various phenomena like wind direction and intensity, atmospheric temperature, urban and rural topography, forest fires, ocean planktonic development, and detection of various constituants such as tropospheric aerosols, stratospheric ozone, trace chemicals and etc. In 2009, a homemade multiwavelength Raman aerosol lidar (named MRC K09) was designed, developed and installed in the Scientific and Technological Research Council of Turkey (TUBITAK) Marmara Research Center (MRC), and since 21 February 2011, it has been accepted to EARLINET (European Aerosol Research Lidar Network). Since 2009, aerosol spatio-temporal distribution and microphysical properties have been investigated in the extremely industrialized vicinity [1,2]. MRC K09 lidar uses a Quantel Brilliant B Nd:YAG laser (1064 nm) with the second and third optical harmonics at 532 and 355 nm, and a homemade Newtonian 40 cm aperture 120 cm focal length telescope. It has 7 channel spectrum analyzer detecting: parallel and perpendicular polarizations at 355 nm, elastic signals at 532 and 1064 nm, Raman signal of molecular nitrogen at 387 nm and Raman signal of water vapor at 408 nm (excited with 355 laser line), and Raman signal for molecular nitrogen at 608 nm (excited with 532 nm laser line). In Spring 2010, preliminary applications for the determination of forest tree species and of forest health in the Black Sea Area using an aeroborne lidar in collaboration with Bartin University, Bartin, Turkey have been made. In early 2011, a fluorescence module utilizing a Princeton Instruments PI-MAX3 1024x256 resolution CCD camera with a Princeton Instruments Acton SP 2500 0.500 m Imaging Triple Grating Monochromator/Spectograph was connected to the MRC K09 lidar system, and the first remote measurements of chlorophyll from different types of trees were made. Figure 1 demonstrates the results of these measurements, which must be considered as preliminary and in the future, the measurements can be carried out by the lidar mounted on an aircraft to cover large spatial areas. One of the most important reasons for biodiversity loss, habitat loss and fragmentation can be monitored in large areas by aeroborne lidars and therefore the extent of the situation can be accessed precisely, faster and more efficiently. This paper aims to give a brief overview to show the possibility of detecting the detailed situations of the habitats on terrain surfaces using lidar technology by summarizing the successful examples which have been realized thus far in different types of ecosystems like savannas, forest and grasslands.

A Search for Laser Emission with Megawatt Thresholds from 5600 FGKM Stars

NASA Astrophysics Data System (ADS)

Tellis, Nathaniel K.; Marcy, Geoffrey W.

2017-06-01

We searched high-resolution spectra of 5600 nearby stars for emission lines that are both inconsistent with a natural origin and unresolved spatially, as would be expected from extraterrestrial optical lasers. The spectra were obtained with the Keck 10 m telescope, including light coming from within 0.5 arcsec of the star, corresponding typically to within a few to tens of astronomical units of the star, and covering nearly the entire visible wavelength range from 3640 to 7890 Å. We establish detection thresholds by injecting synthetic laser emission lines into our spectra and blindly analyzing them for detections. We compute flux density detection thresholds for all wavelengths and spectral types sampled. Our detection thresholds for the power of the lasers themselves range from 3 kW to 13 MW, independent of distance to the star but dependent on the competing “glare” of the spectral energy distribution of the star and on the wavelength of the laser light, launched from a benchmark, diffraction-limited 10 m class telescope. We found no such laser emission coming from the planetary region around any of the 5600 stars. Because they contain roughly 2000 lukewarm, Earth-size planets, we rule out models of the Milky Way in which over 0.1% of warm, Earth-size planets harbor technological civilizations that, intentionally or not, are beaming optical lasers toward us. A next-generation spectroscopic laser search will be done by the Breakthrough Listen initiative, targeting more stars, especially stellar types overlooked here including spectral types O, B, A, early F, late M, and brown dwarfs, and astrophysical exotica.

Generation and characterization of biological aerosols for laser measurements

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

Cheng, Yung-Sung; Barr, E.B.

1995-12-01

Concerns for proliferation of biological weapons including bacteria, fungi, and viruses have prompted research and development on methods for the rapid detection of biological aerosols in the field. Real-time instruments that can distinguish biological aerosols from background dust would be especially useful. Sandia National Laboratories (SNL) is developing a laser-based, real-time instrument for rapid detection of biological aerosols, and ITRI is working with SNL scientists and engineers to evaluate this technology for a wide range of biological aerosols. This paper describes methods being used to generate the characterize the biological aerosols for these tests. In summary, a biosafe system hasmore » been developed for generating and characterizing biological aerosols and using those aerosols to test the SNL laser-based real-time instrument. Such tests are essential in studying methods for rapid detection of airborne biological materials.« less

Technology Development for the LISA Backlink

NASA Astrophysics Data System (ADS)

Chilton, Andrew; Hillsberry, Daniel; Ciani, Giacomo; Coneglian, Michele; Conklin, John; Mueller, Guido

2018-01-01

The LISA mission is a proposed space-based gravitational wave detector that aims to detect gravitational waves in the signal-rich frequency band between 10-4 Hz and 1 Hz. Among the many detection targets are supermassive black hole binary mergers, extreme mass ratio inspirals, and compact galactic binaries. LISA features a constellation of three satellites which fly in an equilateral triangle; by exchanging lasers between the satellites to form interferometers, it can detect passing gravitational waves. While this basic mission concept for LISA has existed for some time, it is not yet finalized. In particular, the design of the laser backlink, which exchanges laser beams between the two local optical benches is still being discussed. In this presentation we discuss the different LISA backlinks, including the classical and modified fiber backlinks, as well as options for a free space backlink. Furthermore, we present results from our free space backlink testbed and plans for future experiments.

Types of Lasers and Their Applications in Pediatric Dentistry

PubMed Central

Nazemisalman, Bahareh; Farsadeghi, Mahya; Sokhansanj, Mehdi

2015-01-01

Laser technology has been recently introduced into the dental field with the idea to replace drilling. Having a less painful first dental experience by the use of modern instruments like laser can be an efficient preventive and therapeutic strategy in pediatric dentistry. Pedodontists need to learn the new less invasive technologies and adopt them in their routine practice. This study aimed to review the available types of lasers and their applications in pediatric dentistry. An electronic search was carried out in IranMedex, InterScience, Scopus, Science Direct, PubMed, ProQuest, Medline and Google Scholar databases to find relevant articles published from 2000 to 2014. Relevant textbooks were reviewed as well. Laser can be used as a suitable alternative to many conventional diagnostic and therapeutic dental procedures. It is especially efficient for caries detection and removal, pulp therapy, lowering the risk of infection, inflammation and swelling and reducing bleeding. On the other hand, due to minimal invasion, laser treatment is well tolerated by children. Improved patient cooperation leads to higher satisfaction of the parents, dentists and the children themselves. PMID:26464775

Editorial special issue on "Laser Doppler vibrometry"

NASA Astrophysics Data System (ADS)

Vanlanduit, Steve; Dirckx, Joris

2017-12-01

The invention of the laser in 1960 has opened up many opportunities in the field of measurement science and technology. Just a few years after the invention of the laser, a novel fluid flow measurement technique based on the Doppler effect was introduced: at that moment the laser Doppler anemometer or shortly LDA [1] was born. The technique enabled fluid velocity measurement by using the light of a He-Ne beam which was scattered by very small polystyrene spheres entrained in the fluid. Later on, in the late nineteen seventees it was recognized that the detection of the Doppler frequency shift that occurs when light is scattered by a moving surface can also be used to measure the vibration velocity of an object. The instrument to perform these vibration measurements was called the laser Doppler vibrometer or LDV [2]. In the last decades several technological advances were made in the field of laser Doppler vibrometry. The result is that nowadays, velocity measurements of fluids (using LDA) and vibrating objects (using LDV) are performed in many challenging applications in different fields (microelectronics, civil structures, biomedical engineering, material science, etc.).

Coherent Doppler Wind Lidar Technology for Space Based Wind Measurements Including SPARCLE

NASA Technical Reports Server (NTRS)

Kavaya, Michael J.; Singh, Upendra N.

1999-01-01

It has been over 30 years since coherent lidar systems first measured wind velocity, and over 20 years since the "ultimate application" of measuring Earth's winds from space was conceived. Coherent or heterodyne optical detection involves the combination (or mixing) of the returned optical field with a local oscillator (LO) laser's optical field on the optical detector. This detection technique yields the benefits of dramatically improved signal-to-noise ratios; insensitivity to detector noise, background light and multiply scattered light; reduction of the returned signal's dynamic range; and preservation of the optical signal spectrum for electronic and computer processing. (Note that lidar systems are also referred to as optical radar, laser radar, and LADAR systems.) Many individuals, agencies, and countries have pursued the goal of space-based wind measurements through technology development, experiments, field campaigns and studies.

Nondestructive Inspection System for Special Nuclear Material Using Inertial Electrostatic Confinement Fusion Neutrons and Laser Compton Scattering Gamma-Rays

NASA Astrophysics Data System (ADS)

Ohgaki, H.; Daito, I.; Zen, H.; Kii, T.; Masuda, K.; Misawa, T.; Hajima, R.; Hayakawa, T.; Shizuma, T.; Kando, M.; Fujimoto, S.

2017-07-01

A Neutron/Gamma-ray combined inspection system for hidden special nuclear materials (SNMs) in cargo containers has been developed under a program of Japan Science and Technology Agency in Japan. This inspection system consists of an active neutron-detection system for fast screening and a laser Compton backscattering gamma-ray source in coupling with nuclear resonance fluorescence (NRF) method for precise inspection. The inertial electrostatic confinement fusion device has been adopted as a neutron source and two neutron-detection methods, delayed neutron noise analysis method and high-energy neutron-detection method, have been developed to realize the fast screening system. The prototype system has been constructed and tested in the Reactor Research Institute, Kyoto University. For the generation of the laser Compton backscattering gamma-ray beam, a race track microtron accelerator has been used to reduce the size of the system. For the NRF measurement, an array of LaBr3(Ce) scintillation detectors has been adopted to realize a low-cost detection system. The prototype of the gamma-ray system has been demonstrated in the Kansai Photon Science Institute, National Institutes for Quantum and Radiological Science and Technology. By using numerical simulations based on the data taken from these prototype systems and the inspection-flow, the system designed by this program can detect 1 kg of highly enriched 235U (HEU) hidden in an empty 20-ft container within several minutes.

Airborne laser scanning of forest resources: An overview of research in Italy as a commentary case study

NASA Astrophysics Data System (ADS)

Montaghi, Alessandro; Corona, Piermaria; Dalponte, Michele; Gianelle, Damiano; Chirici, Gherardo; Olsson, Håkan

2013-08-01

This article reviews the recent literature concerning airborne laser scanning for forestry purposes in Italy, and presents the current methodologies used to extract forest characteristics from discrete return ALS (Airborne Laser Scanning) data. Increasing interest in ALS data is currently being shown, especially for remote sensing-based forest inventories in Italy; the driving force for this interest is the possibility of reducing costs and providing more accurate and efficient estimation of forest characteristics. This review covers a period of approximately ten years, from the first application of laser scanning for forestry purposes in 2003 to the present day, and shows that there are numerous ongoing research activities which use these technologies for the assessment of forest attributes (e.g., number of trees, mean tree height, stem volume) and ecological issues (e.g., gap identification, fuel model detection). The basic approaches - such as single tree detection and area-based modeling - have been widely examined and commented in order to explore the trend of methods in these technologies, including their applicability and performance. Finally this paper outlines and comments some of the common problems encountered in operational use of laser scanning in Italy, offering potentially useful guidelines and solutions for other countries with similar conditions, under a rather variable environmental framework comprising Alpine, temperate and Mediterranean forest ecosystems.

Plasma spectrum peak extraction algorithm of laser film damage

NASA Astrophysics Data System (ADS)

Zhao, Dan; Su, Jun-hong; Xu, Jun-qi

2012-10-01

The plasma spectrometry is an emerging method to distinguish the thin-film laser damage. Laser irradiation film surface occurrence of flash, using the spectrometer receives the flash spectrum, extracting the spectral peak, and by means of the spectra of the thin-film materials and the atmosphere has determine the difference, as a standard to determine the film damage. Plasma spectrometry can eliminate the miscarriage of justice which caused by atmospheric flashes, and distinguish high accuracy. Plasma spectra extraction algorithm is the key technology of Plasma spectrometry. Firstly, data de noising and smoothing filter is introduced in this paper, and then during the peak is detecting, the data packet is proposed, and this method can increase the stability and accuracy of the spectral peak recognition. Such algorithm makes simultaneous measurement of Plasma spectrometry to detect thin film laser damage, and greatly improves work efficiency.

Parameters effects study on pulse laser for the generation of surface acoustic waves in human skin detection applications

NASA Astrophysics Data System (ADS)

Li, Tingting; Fu, Xing; Dorantes-Gonzalez, Dante J.; Chen, Kun; Li, Yanning; Wu, Sen

2015-10-01

Laser-induced Surface Acoustic Waves (LSAWs) has been promisingly and widely used in recent years due to its rapid, high accuracy and non-contact evaluation potential of layered and thin film materials. For now, researchers have applied this technology on the characterization of materials' physical parameters, like Young's Modulus, density, and Poisson's ratio; or mechanical changes such as surface cracks and skin feature like a melanoma. While so far, little research has been done on providing practical guidelines on pulse laser parameters to best generate SAWs. In this paper finite element simulations of the thermos-elastic process based on human skin model for the generation of LSAWs were conducted to give the effects of pulse laser parameters have on the generated SAWs. And recommendations on the parameters to generate strong SAWs for detection and surface characterization without cause any damage to skin are given.

Experimental evaluation of penetration capabilities of a Geiger-mode APD array laser radar system

NASA Astrophysics Data System (ADS)

Jonsson, Per; Tulldahl, Michael; Hedborg, Julia; Henriksson, Markus; Sjöqvist, Lars

2017-10-01

Laser radar 3D imaging has the potential to improve target recognition in many scenarios. One case that is challenging for most optical sensors is to recognize targets hidden in vegetation or behind camouflage. The range resolution of timeof- flight 3D sensors allows segmentation of obscuration and target if the surfaces are separated far enough so that they can be resolved as two distances. Systems based on time-correlated single-photon counting (TCSPC) have the potential to resolve surfaces closer to each other compared to laser radar systems based on proportional mode detection technologies and is therefore especially interesting. Photon counting detection is commonly performed with Geigermode Avalanche Photodiodes (GmAPD) that have the disadvantage that they can only detect one photon per laser pulse per pixel. A strong return from an obscuring object may saturate the detector and thus limit the possibility to detect the hidden target even if photons from the target reach the detector. The operational range where good foliage penetration is observed is therefore relatively narrow for GmAPD systems. In this paper we investigate the penetration capability through semi-transparent surfaces for a laser radar with a 128×32 pixel GmAPD array and a 1542 nm wavelength laser operating at a pulse repetition frequency of 90 kHz. In the evaluation a screen was placed behind different canvases with varying transmissions and the detected signals from the surfaces for different laser intensities were measured. The maximum return from the second surface occurs when the total detection probability is around 0.65-0.75 per pulse. At higher laser excitation power the signal from the second surface decreases. To optimize the foliage penetration capability it is thus necessary to adaptively control the laser power to keep the returned signal within this region. In addition to the experimental results, simulations to study the influence of the pulse energy on penetration through foliage in a scene with targets behind vegetation are presented. The optimum detection of targets occurs here at a slightly higher total photon count rate probability because a number of pixel have no obscuration in front the target in their field of view.

Study of noninvasive detection of latent fingerprints using UV laser

NASA Astrophysics Data System (ADS)

Li, Hong-xia; Cao, Jing; Niu, Jie-qing; Huang, Yun-gang; Mao, Lin-jie; Chen, Jing-rong

2011-06-01

Latent fingerprints present a considerable challenge in forensics, and noninvasive procedure that captures a digital image of the latent fingerprints is significant in the field of criminal investigation. The capability of photography technologies using 266nm UV Nd:YAG solid state laser as excitation light source to provide detailed images of unprocessed latent fingerprints is demonstrated. Unprocessed latent fingerprints were developed on various non-absorbent and absorbing substrates. According to the special absorption, reflection, scattering and fluorescence characterization of the various residues in fingerprints (fatty acid ester, protein, and carbosylic acid salts etc) to the UV light to weaken or eliminate the background disturbance and increase the brightness contrast of fingerprints with the background, and using 266nm UV laser as excitation light source, fresh and old latent fingerprints on the surface of four types of non-absorbent objects as magazine cover, glass, back of cellphone, wood desktop paintwork and two types of absorbing objects as manila envelope, notebook paper were noninvasive detected and appeared through reflection photography and fluorescence photography technologies, and the results meet the fingerprint identification requirements in forensic science.

Highly Sensitive Tunable Diode Laser Spectrometers for In Situ Planetary Exploration

NASA Technical Reports Server (NTRS)

Vasudev, Ram; Mansour, Kamjou; Webster, Christopher R.

2013-01-01

This paper describes highly sensitive tunable diode laser spectrometers suitable for in situ planetary exploration. The technology developed at JPL is based on wavelength modulated cavity enhanced absorption spectroscopy. It is capable of sensitively detecting chemical signatures of life through the abundance of biogenic molecules and their isotopic composition, and chemicals such as water necessary for habitats of life. The technology would be suitable for searching for biomarkers, extinct life, potential habitats of extant life, and signatures of ancient climates on Mars; and for detecting biomarkers, prebiotic chemicals and habitats of life in the outer Solar System. It would be useful for prospecting for water on the Moon and asteroids, and characterizing its isotopic composition. Deployment on the Moon could provide ground truth to the recent remote measurements and help to uncover precious records of the early bombardment history of the inner Solar System buried at the shadowed poles, and elucidate the mechanism for the generation of near-surface water in the illuminated regions. The technology would also be useful for detecting other volatile molecules in planetary atmospheres and subsurface reservoirs, isotopic characterization of planetary materials, and searching for signatures of extinct life preserved in solid matrices.

Laser-based standoff detection of surface-bound explosive chemicals

NASA Astrophysics Data System (ADS)

Huestis, David L.; Smith, Gregory P.; Oser, Harald

2010-04-01

Avoiding or minimizing potential damage from improvised explosive devices (IEDs) such as suicide, roadside, or vehicle bombs requires that the explosive device be detected and neutralized outside its effective blast radius. Only a few seconds may be available to both identify the device as hazardous and implement a response. As discussed in a study by the National Research Council, current technology is still far from capable of meeting these objectives. Conventional nitrocarbon explosive chemicals have very low vapor pressures, and any vapors are easily dispersed in air. Many pointdetection approaches rely on collecting trace solid residues from dust particles or surfaces. Practical approaches for standoff detection are yet to be developed. For the past 5 years, SRI International has been working toward development of a novel scheme for standoff detection of explosive chemicals that uses infrared (IR) laser evaporation of surfacebound explosive followed by ultraviolet (UV) laser photofragmentation of the explosive chemical vapor, and then UV laser-induced fluorescence (LIF) of nitric oxide. This method offers the potential of long standoff range (up to 100 m or more), high sensitivity (vaporized solid), simplicity (no spectrometer or library of reference spectra), and selectivity (only nitrocompounds).

Caries diagnosis using laser fluorescence

NASA Astrophysics Data System (ADS)

Zanin, Fatima A. A.; Pinheiro, Antonio L. B.; Souza-Campos, Dilma H.; Brugnera, Aldo, Jr.; Pecora, Jesus D.

2000-03-01

Caries prevention is a goal to be achieved by dentist in order to promote health. There are several methods used to detect dental caries each one presenting advantages and disadvantages, especially regarding hidden occlusal caries. The improvement of laser technology has permitted the use of laser fluorescence for early diagnosis of hidden occlusal caries. The aim of this study was to assess the efficacy of the use of 655 nm laser light on the detection of hidden occlusal caries. Forty molar teeth from patients of both sexes which ages ranging from 10 - 18 years old were used on this study. Following manufacture's instructions regarding the use of the equipment, the teeth had their occlusal surface examined with the DIAGNOdent. Twenty six of 40 teeth had hidden occlusal caries detected by the DIAGNOdent. However only 17 of these 26 teeth showed radiographic signs of caries the other 9 teeth showed no radiological signs of the lesion. Radiographic examination was able to identify 34,61% of false negative cases. This means that many caries would be left untreated due to the lack of diagnosis using both visual and radiographic examination. The use of the DIAGNOdent was effective in successfully detecting hidden occlusal caries.

DOE Center of Excellence in Medical Laser Applications. Final report

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

Jacques, S.L.

1998-01-01

An engineering network of collaborating medical laser laboratories are developing laser and optical technologies for medical diagnosis and therapy and are translating the engineering into medical centers in Portland, OR, Houston, TX, and Galveston, TX. The Center includes the University of Texas M.D. Anderson Cancer Center, the University of Texas-Austin, Texas A and M University, Rice University, the University Texas Medical Branch-Galveston, Oregon Medical Laser Center (Providence St. Vincent Medical Center, Oregon Health Sciences University, and Oregon Graduate Institute, Portland, OR), and the University of Oregon. Diagnostics include reflectance, fluorescence, Raman IR, laser photoacoustics, optical coherence tomography, and several newmore » video techniques for spectroscopy and imaging. Therapies include photocoagulation therapy, laser welding, pulsed laser ablation, and light-activated chemotherapy of cancer (photodynamic therapy, or PDT). Medical applications reaching the clinic include optical monitoring of hyperbilirubinemia in newborns, fluorescence detection of cervical dysplasia, laser thrombolysis of blood clots in heart attack and brain stroke, photothermal coagulation of benign prostate hyperplasia, and PDT for both veterinary and human cancer. New technologies include laser optoacoustic imaging of breast tumors and hemorrhage in head trauma and brain stroke, quality control monitoring of dosimetry during PDT for esophageal and lung cancer, polarization video reflectometry of skin cancer, laser welding of artificial tissue replacements, and feedback control of laser welding.« less

DOE Center of Excellence in Medical Laser Applications. Final report, December 1, 1994--November 30, 1997

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

Jacques, S.L.

1998-01-01

An engineering network of collaborating medical laser laboratories are developing laser and optical technologies for medical diagnosis and therapy and are translating the engineering into medical centers in Portland OR, Houston TX, and Galveston TX. The Center includes the University of Texas M.D. Anderson Cancer Center, the University of Texas-Austin, Texas A and M University, Rice University, the University Texas Medical Branch-Galveston, Oregon Medical Laser Center (Providence St. Vincent Medical Center, Oregon Health Sciences University, and Oregon Graduate Institute, Portland, OR), and the University of Oregon. Diagnostics include reflectance, fluorescence, Raman IR, laser photoacoustics, optical coherence tomography, and several newmore » video techniques for spectroscopy and imaging. Therapies include photocoagulation therapy, laser welding, pulsed laser ablation, and light-activated chemotherapy of cancer (photodynamic therapy, or PDT). Medical applications reaching the clinic include optical monitoring of hyperbilirubinemia in newborns, fluorescence detection of cervical dysplasia, laser thrombolysis of blood clots in heart attack and brain stroke, photothermal coagulant of benign prostate hyperplasia, and PDT for both veterinary and human cancer. New technologies include laser optoacoustic imaging of breast tumors and hemorrhage in head trauma and brain stroke, quality control monitoring of dosimetry during PDT for esophageal and lung cancer, polarization video reflectometry of skin cancer, laser welding of artificial tissue replacements, and feedback control of laser welding.« less

Integrated bio-fluorescence sensor.

PubMed

Thrush, Evan; Levi, Ofer; Ha, Wonill; Wang, Ke; Smith, Stephen J; Harris, James S

2003-09-26

Due to the recent explosion in optoelectronics for telecommunication applications, novel optoelectronic sensing structures can now be realized. In this work, we explore the integration of optoelectronic components towards miniature and portable fluorescence sensors. The integration of these micro-fabricated sensors with microfluidics and capillary networks may reduce the cost and complexity of current research instruments and open up a world of new applications in portable biological analysis systems. A novel optoelectronic design that capitalizes on current vertical-cavity surface-emitting laser (VCSEL) technology is explored. Specifically, VCSELs, optical emission filters and PIN photodetectors are fabricated as part of a monolithically integrated near-infrared fluorescence detection system. High-performance lasers and photodetectors have been characterized and integrated to form a complete sensor. Experimental results show that sensor sensitivity is limited by laser background. The laser background is caused by spontaneous emission emitted from the side of the VCSEL excitation source. Laser background will limit sensitivity in most integrated sensing designs due to locating excitation sources and photodetectors in such close proximity, and methods are proposed to reduce the laser background in such designs so that practical fluorescent detection limits can be achieved.

Measurement of tropospheric OH and HO2 by laser-induced fluorescence at low pressure

NASA Technical Reports Server (NTRS)

Stevens, P. S.; Mather, J. H.; Brune, W. H.

1994-01-01

The hydroxyl radical (OH) is the primary oxidant in the atmosphere, responsible for many photochemical reactions that affect both regional air quality and global climate change. Because of its high reactivity, abundances of OH in the troposphere are less than 1 part per trillion by volume (pptv) and thus difficult to measure accurately. This paper describes an instrument for the sensitive detection of OH in the troposphere using low-pressure laser-induced fluorescence. Ambient air is expanded into a low pressure detection chamber, and OH is both excited and detected using the A(sup 2) Epsilon(+)(v prime = 0) yields X(sup 2)Pi(v double prime = 0) transition near 308 nm. An injector upstream of the detection axis allows for the addition of reagent NO to convert ambient HO2 to OH using the fast reaction HO2 + NO yields OH + NO2. Using recent advances in laser and detector technologies, this prototype instrument is able to detect less than 1 x 10(exp 5) molecules/cu cm (0.004 pptv) of OH with an integration time of 30 s with negligible interferences.

Compact atom interferometer using single laser

NASA Astrophysics Data System (ADS)

Chiow, Sheng-Wey; Yu, Nan

2017-04-01

Atom interferometer (AI) based sensors exhibit precision and accuracy unattainable with classical sensors, thanks to the inherent stability of atomic properties. The complexity of required laser system and the size of vacuum chamber driven by optical access requirement limit the applicability of such technology in size, weight, and power (SWaP) challenging environments, such as in space. For instance, a typical physics package of AI includes six viewports for laser cooling and trapping, two for AI beams, and two more for detection and a vacuum pump. Similarly, a typical laser system for an AI includes two lasers for cooling and repumping, and two for Raman transitions as AI beam splitters. In this presentation, we report our efforts in developing a miniaturized atomic accelerometer for planetary exploration. We will describe a physics package configuration having minimum optical access (thus small volume), and a laser and optics system utilizing a single laser for the sensor operation. Preliminary results on acceleration sensitivity will be discussed. We will also illustrate a path for further packaging and integration based on the demonstrated concepts. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

Quantum cascade lasers (QCL) for active hyperspectral imaging

NASA Astrophysics Data System (ADS)

Yang, Quankui; Fuchs, Frank; Wagner, Joachim

2014-04-01

There is an increasing demand for wavelength agile laser sources covering the mid-infrared (MIR, 3.5-12 µm) wavelength range, among others in active imaging. The MIR range comprises a particularly interesting part of the electromagnetic spectrum for active hyperspectral imaging applications, due to the fact that the characteristic `fingerprint' absorption spectra of many chemical compounds lie in that range. Conventional semiconductor diode laser technology runs out of steam at such long wavelengths. For many applications, MIR coherent light sources based on solid state lasers in combination with optical parametric oscillators are too complex and thus bulky and expensive. In contrast, quantum cascade lasers (QCLs) constitute a class of very compact and robust semiconductor-based lasers, which are able to cover the mentioned wavelength range using the same semiconductor material system. In this tutorial, a brief review will be given on the state-of-the-art of QCL technology. Special emphasis will be addressed on QCL variants with well-defined spectral properties and spectral tunability. As an example for the use of wavelength agile QCL for active hyperspectral imaging, stand-off detection of explosives based on imaging backscattering laser spectroscopy will be discussed.

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

Hartemann, F V; Albert, F; Anderson, S G

Nuclear photonics is an emerging field of research requiring new tools, including high spectral brightness, tunable gamma-ray sources; high photon energy, ultrahigh-resolution crystal spectrometers; and novel detectors. This presentation focuses on the precision linac technology required for Compton scattering gamma-ray light sources, and on the optimization of the laser and electron beam pulse format to achieve unprecedented spectral brightness. Within this context, high-gradient X-band technology will be shown to offer optimal performance in a compact package, when used in conjunction with the appropriate pulse format, and photocathode illumination and interaction laser technologies. The nascent field of nuclear photonics is enabledmore » by the recent maturation of new technologies, including high-gradient X-band electron acceleration, robust fiber laser systems, and hyper-dispersion CPA. Recent work has been performed at LLNL to demonstrate isotope-specific detection of shielded materials via NRF using a tunable, quasi-monochromatic Compton scattering gamma-ray source operating between 0.2 MeV and 0.9 MeV photon energy. This technique is called Fluorescence Imaging in the Nuclear Domain with Energetic Radiation (or FINDER). This work has, among other things, demonstrated the detection of {sup 7}Li shielded by Pb, utilizing gamma rays generated by a linac-driven, laser-based Compton scattering gamma-ray source developed at LLNL. Within this context, a new facility is currently under construction at LLNL, with the goal of generating tunable {gamma}-rays in the 0.5-2.5 MeV photon energy range, at a repetition rate of 120 Hz, and with a peak brightness in the 10{sup 20} photons/(s x mm{sup 2} x mrad{sup 2} x 0.1% bw).« less

Enhanced photothermal lens using a photonic crystal surface

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

Zhao, Yunfei; Liu, Longju; Zhao, Xiangwei

2016-08-15

A photonic crystal (PC)-enhanced photothermal lens (PTL) is demonstrated for the detection of optically thin light absorption materials. The PC-enhanced PTL system is based on a pump-probe scheme consisting of a PC surface, pump laser beam, and probe laser beam. Heated by the pump beam, light absorption materials on the PC surface generate the PTL and cause a substantial change to the guided-mode resonance supported by the PC structure. The change of the PC resonance is detected using the probe laser beam by measuring its reflectivity from the PC surface. When applied to analyze dye molecules deposited on the PCmore » substrate, the developed system is capable of enhancing the PTL signal by 10-fold and reducing the lowest distinguishable concentration by 8-fold, in comparison to measuring without utilizing the PC resonance. The PC-enhanced PTL was also used to detect gold nanoparticles on the PC surface and exhibited a 20-fold improvement of the lowest distinguishable concentration. The PC-enhanced PTL technology offers a potential tool to obtain the absorption signatures of thin films in a broad spectral range with high sensitivity and inexpensive instrumentation. As a result, this technology will enable a broad range of applications of photothermal spectroscopy in chemical analysis and biomolecule sensing.« less

REAL-TIME IN SITU DETECTION OF ORGANIC CONTAMINANTS BY LASER-INDUCED FLUORESCENCE SYSTEM. Final tropical report (Task 1.3).

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

Daniel J. Stepan; James A. Sorensen; Jaroslav Solc

This report summarizes the results of the field demonstration of a laser-induced fluorescence (LIF) method for characterization of brownfields and other contaminated sites. The technology was provided and demonstrated by Dakota Technologies, Inc. (DTI), of Fargo, North Dakota. LIF generates continuous data on the distribution of polycyclic aromatic hydrocarbons (PAHs) within the soil profile. The sensor used to record real-time data is deployed into the soil using a modified truck-mounted Geoprobe percussion soil probing device. The summary of observations described in the following text represents an independent evaluation of the performance, usefulness, and economics of the demonstrated technology for characterizationmore » at PAH-contaminated sites.« less

A guide to LIDAR data acquisition and processing for the forests of the Pacific Northwest.

Treesearch

Demetrios Gatziolis; Hans-Erik Andersen

2008-01-01

Light detection and ranging (LIDAR) is an emerging remote-sensing technology with promising potential to assist in mapping, monitoring, and assessment of forest resources. Continuous technological advancement and substantial reductions in data acquisition cost have enabled acquisition of laser data over entire states and regions. These developments have triggered an...

Light Detection and Ranging-Based Terrain Navigation: A Concept Exploration

NASA Technical Reports Server (NTRS)

Campbell, Jacob; UijtdeHaag, Maarten; vanGraas, Frank; Young, Steve

2003-01-01

This paper discusses the use of Airborne Light Detection And Ranging (LiDAR) equipment for terrain navigation. Airborne LiDAR is a relatively new technology used primarily by the geo-spatial mapping community to produce highly accurate and dense terrain elevation maps. In this paper, the term LiDAR refers to a scanning laser ranger rigidly mounted to an aircraft, as opposed to an integrated sensor system that consists of a scanning laser ranger integrated with Global Positioning System (GPS) and Inertial Measurement Unit (IMU) data. Data from the laser range scanner and IMU will be integrated with a terrain database to estimate the aircraft position and data from the laser range scanner will be integrated with GPS to estimate the aircraft attitude. LiDAR data was collected using NASA Dryden's DC-8 flying laboratory in Reno, NV and was used to test the proposed terrain navigation system. The results of LiDAR-based terrain navigation shown in this paper indicate that airborne LiDAR is a viable technology enabler for fully autonomous aircraft navigation. The navigation performance is highly dependent on the quality of the terrain databases used for positioning and therefore high-resolution (2 m post-spacing) data was used as the terrain reference.

Semiconductor Reference Oscillator Development for Coherent Detection Optical Remote Sensing Applications

NASA Technical Reports Server (NTRS)

Tratt, David M.; Mansour, Kamjou; Menzies, Robert T.; Qiu, Yueming; Forouhar, Siamak; Maker, Paul D.; Muller, Richard E.

2001-01-01

The NASA Earth Science Enterprise Advanced Technology Initiatives Program is supporting a program for the development of semiconductor laser reference oscillators for application to coherent optical remote sensing from Earth orbit. Local oscillators provide the frequency reference required for active spaceborne optical remote sensing concepts that involve heterodyne (coherent) detection. Two recent examples of such schemes are Doppler wind lidar and tropospheric carbon dioxide measurement by laser absorption spectrometry, both of which are being proposed at a wavelength of 2.05 microns. Frequency-agile local oscillator technology is important to such applications because of the need to compensate for large platform-induced Doppler components that would otherwise interfere with data interpretation. Development of frequency-agile local oscillator approaches has heretofore utilized the same laser material as the transmitter laser (Tm,Ho:YLF in the case of the 2.05-micron wavelength mentioned above). However, a semiconductor laser-based frequency-agile local oscillator offers considerable scope for reduced mechanical complexity and improved frequency agility over equivalent crystal laser devices, while their potentially faster tuning capability suggest the potential for greater scanning versatility. The program we report on here is specifically tasked with the development of prototype novel architecture semiconductor lasers with the power, tunability, and spectral characteristics required for coherent Doppler lidar. The baseline approach for this work is the distributed feedback (DFB) laser, in which gratings are etched into the semiconductor waveguide structures along the entire length of the laser cavity. However, typical DFB lasers at the wavelength of interest have linewidths that exhibit unacceptable growth when driven at the high currents and powers that are required for the Doppler lidar application. Suppression of this behavior by means of corrugation pitch-modulation (using a detuned central section to prevent intensity peaking in the center of the cavity) is currently under investigation to achieve the required performance goals.

Design of a dual species atom interferometer for space

NASA Astrophysics Data System (ADS)

Schuldt, Thilo; Schubert, Christian; Krutzik, Markus; Bote, Lluis Gesa; Gaaloul, Naceur; Hartwig, Jonas; Ahlers, Holger; Herr, Waldemar; Posso-Trujillo, Katerine; Rudolph, Jan; Seidel, Stephan; Wendrich, Thijs; Ertmer, Wolfgang; Herrmann, Sven; Kubelka-Lange, André; Milke, Alexander; Rievers, Benny; Rocco, Emanuele; Hinton, Andrew; Bongs, Kai; Oswald, Markus; Franz, Matthias; Hauth, Matthias; Peters, Achim; Bawamia, Ahmad; Wicht, Andreas; Battelier, Baptiste; Bertoldi, Andrea; Bouyer, Philippe; Landragin, Arnaud; Massonnet, Didier; Lévèque, Thomas; Wenzlawski, Andre; Hellmig, Ortwin; Windpassinger, Patrick; Sengstock, Klaus; von Klitzing, Wolf; Chaloner, Chris; Summers, David; Ireland, Philip; Mateos, Ignacio; Sopuerta, Carlos F.; Sorrentino, Fiodor; Tino, Guglielmo M.; Williams, Michael; Trenkel, Christian; Gerardi, Domenico; Chwalla, Michael; Burkhardt, Johannes; Johann, Ulrich; Heske, Astrid; Wille, Eric; Gehler, Martin; Cacciapuoti, Luigi; Gürlebeck, Norman; Braxmaier, Claus; Rasel, Ernst

2015-06-01

Atom interferometers have a multitude of proposed applications in space including precise measurements of the Earth's gravitational field, in navigation & ranging, and in fundamental physics such as tests of the weak equivalence principle (WEP) and gravitational wave detection. While atom interferometers are realized routinely in ground-based laboratories, current efforts aim at the development of a space compatible design optimized with respect to dimensions, weight, power consumption, mechanical robustness and radiation hardness. In this paper, we present a design of a high-sensitivity differential dual species 85Rb/87Rb atom interferometer for space, including physics package, laser system, electronics and software. The physics package comprises the atom source consisting of dispensers and a 2D magneto-optical trap (MOT), the science chamber with a 3D-MOT, a magnetic trap based on an atom chip and an optical dipole trap (ODT) used for Bose-Einstein condensate (BEC) creation and interferometry, the detection unit, the vacuum system for 10-11 mbar ultra-high vacuum generation, and the high-suppression factor magnetic shielding as well as the thermal control system. The laser system is based on a hybrid approach using fiber-based telecom components and high-power laser diode technology and includes all laser sources for 2D-MOT, 3D-MOT, ODT, interferometry and detection. Manipulation and switching of the laser beams is carried out on an optical bench using Zerodur bonding technology. The instrument consists of 9 units with an overall mass of 221 kg, an average power consumption of 608 W (814 W peak), and a volume of 470 liters which would well fit on a satellite to be launched with a Soyuz rocket, as system studies have shown.

[Research on inorganic explosive and its principal component with laser-induced breakdown spectroscopy].

PubMed

Zhao, Hua; Wang, Qian-qian; Liu, Kai; Ge, Cong-hui

2012-03-01

Laser-induced breakdown spectroscopy is a technology that can be used for high-speed, real time, multi-component, online, remote detection, and it has considerable superiority in explosives detection. In the present experiment, using 1 064 nm Q-switch laser beam as the resource, the authors investigated a common inorganic explosive (black powder) and one of its key components (KNO3), while choosing NaNO3 as the reference. We obtained the LIBS spectroscopy of these three samples in two surrounding atmospheres (air and Ar gas) at different time delay. And we analysed the change in line intensity ratio of N, O along with the increase in time delay, and found that the maximum of the value of O/N is obtained at time delay 596 ns.

Explosive detection technology

NASA Astrophysics Data System (ADS)

Doremus, Steven; Crownover, Robin

2017-05-01

The continuing proliferation of improvised explosive devices is an omnipresent threat to civilians and members of military and law enforcement around the world. The ability to accurately and quickly detect explosive materials from a distance would be an extremely valuable tool for mitigating the risk posed by these devices. A variety of techniques exist that are capable of accurately identifying explosive compounds, but an effective standoff technique is still yet to be realized. Most of the methods being investigated to fill this gap in capabilities are laser based. Raman spectroscopy is one such technique that has been demonstrated to be effective at a distance. Spatially Offset Raman Spectroscopy (SORS) is a technique capable of identifying chemical compounds inside of containers, which could be used to detect hidden explosive devices. Coherent Anti-Stokes Raman Spectroscopy (CARS) utilized a coherent pair of lasers to excite a sample, greatly increasing the response of sample while decreasing the strength of the lasers being used, which significantly improves the eye safety issue that typically hinders laser-based detection methods. Time-gating techniques are also being developed to improve the data collection from Raman techniques, which are often hindered fluorescence of the test sample in addition to atmospheric, substrate, and contaminant responses. Ultraviolet based techniques have also shown significant promise by greatly improved signal strength from excitation of resonance in many explosive compounds. Raman spectroscopy, which identifies compounds based on their molecular response, can be coupled with Laser Induced Breakdown Spectroscopy (LIBS) capable of characterizing the sample's atomic composition using a single laser.

Novel laser induced photoacoustic spectroscopy for instantaneous trace detection of explosive materials.

PubMed

El-Sharkawy, Yasser H; Elbasuney, Sherif

2017-08-01

Laser photoacoustic spectroscopy (LPAS) is an attractive technology in terms of simplicity, ruggedness, and overall sensitivity; it detects the time dependent heat generated (thermo-elastic effect) in the target via interaction with pulsed optical radiation. This study reports on novel LPAS technique that offers instant and standoff detection capabilities of trace explosives. Over the current study, light is generated using pulsed Q-switched Nd:YAG laser; the generated photoacoustic response in stimulated explosive material offers signature values that depend on the optical, thermal, and acoustical properties. The generated acoustic waves were captured using piezoelectric transducer as well as novel customized optical sensor with remotely laser interferometer probe. A digital signal processing algorithm was employed to identify explosive material signatures via calculation of characteristic optical properties (absorption coefficient), sound velocity, and frequency response of the generated photoacoustic signal. Customized LPAS technique was employed for instantaneous trace detection of three main different high explosive materials including TNT, RDX, and HMX. The main outcome of this study is that the novel customized optical sensor signals were validated with traditional piezoelectric transducer. Furthermore, the customized optical sensor offered standoff detection capabilities (10cm), fast response, high sensitivity, and enhanced signal to noise ratio. This manuscript shaded the light on the instant detection of trace explosive materials from significant standoffs using novel customized LPAS technique. Copyright © 2017 Elsevier B.V. All rights reserved.

Detection and quantification of explosives and CWAs using a handheld widely tunable quantum cascade laser

NASA Astrophysics Data System (ADS)

Deutsch, Erik R.; Haibach, Frederick G.; Mazurenko, Alexander

2012-06-01

The requirements for standoff detection of Explosives and CWA/TICs on surfaces in the battlefield are challenging because of the low detection limits. The variety of targets, backgrounds and interferences increase the challenges. Infrared absorption spectroscopy with traditional infrared detection technologies, incandescent sources that offer broad wavelength range but poor spectral intensity, are particularly challenged in standoff applications because most photons are lost to the target, background and the environment. Using a brighter source for active infrared detection e.g. a widely-tunable quantum cascade laser (QCL) source, provides sufficient spectral intensity to achieve the needed sensitivity and selectivity for explosives, CWAs, and TICs on surfaces. Specific detection of 1-10 μg/cm2 is achieved within seconds. CWAs, and TICs in vapor and aerosol form present a different challenge. Vapors and aerosols are present at low concentrations, so long pathlengths are required to achieve the desired sensitivity. The collimated output beam from the QCL simplifies multi-reflection cells for vapor detection while also enabling large standoff distances. Results obtained by the QCL system indicate that <1 ppm for vapors can be achieved with specificity in a measurement time of seconds, and the QCL system was successfully able to detect agents in the presence of interferents. QCLs provide additional capabilities for the dismounted warfighter. Given the relatively low power consumption, small package, and instant-on capability of the QCL, a handheld device can provide field teams with early detection of toxic agents and energetic materials in standoff, vapor, or aerosol form using a single technology and device which makes it attractive compared other technologies.

Intentionally Short-Range Communications (ISRC)

NASA Astrophysics Data System (ADS)

Yen, J.; Poirier, P.; Obrien, M.

1994-02-01

The U.S. Marine Corps (USMC) desired to develop short-range communications links whose ranges are intentionally limited to very short distances. These links support tactical missions such as LAN Backbone, Wideband Data Link, and Company Radio. The short-range limitation arises from the need for low probability of detection and intercept (LPD/LPI). Since the detection of an undecipherable transmission would still provide an enemy with information regarding transmitter location and allow him to take countermeasures, the Marine Corps Systems Command (MARCORSYSCOM) is sponsoring the development of technologies that can be LPD by their very nature. The Intentionally Short-Range Communications (ISRC) project at the Naval Command, Control and Ocean Surveillance Center (NCCOSC) RDT&E Division (NRaD) is pursuing feasibility studies for these USMC missions based on such technologies as ultraviolet (LTV) lamps, UV lasers, infrared (IR) lasers, millimeter waves and direct sequence spread spectrum (DSSS) at radio frequencies.

[Open-path online monitoring of ambient atmospheric CO2 based on laser absorption spectrum].

PubMed

He, Ying; Zhang, Yu-Jun; Kan, Rui-Feng; Xia, Hui; Geng, Hui; Ruan, Jun; Wang, Min; Cui, Xiao-Juan; Liu, Wen-Qing

2009-01-01

With the conjunction of tunable diode laser absorption spectroscopy technology (TDLAS) and the open long optical path technology, the system designing scheme of CO2 on-line monitoring based on near infrared tunable diode laser absorption spectroscopy technology was discussed in detail, and the instrument for large-range measurement was set up. By choosing the infrared absorption line of CO2 at 1.57 microm whose line strength is strong and suitable for measurement, the ambient atmospheric CO2 was measured continuously with a 30 s temporal resolution at an suburb site in the autumn of 2007. The diurnal atmospheric variations of CO2 and continuous monitoring results were presented. The results show that the variation in CO2 concentration has an obvious diurnal periodicity in suburb where the air is free of interference and contamination. The general characteristic of diurnal variation is that the concentration is low in the daytime and high at night, so it matches the photosynthesis trend. The instrument can detect gas concentration online with high resolution, high sensitivity, high precision, short response time and many other advantages, the monitoring requires no gas sampling, the calibration is easy, and the detection limit is about 4.2 x 10(-7). It has been proved that the system and measurement project are feasible, so it is an effective method for gas flux continuous online monitoring of large range in ecosystem based on TDLAS technology.

Diode laser absorption sensors for gas-dynamic and combustion flows

NASA Technical Reports Server (NTRS)

Allen, M. G.

1998-01-01

Recent advances in room-temperature, near-IR and visible diode laser sources for tele-communication, high-speed computer networks, and optical data storage applications are enabling a new generation of gas-dynamic and combustion-flow sensors based on laser absorption spectroscopy. In addition to conventional species concentration and density measurements, spectroscopic techniques for temperature, velocity, pressure and mass flux have been demonstrated in laboratory, industrial and technical flows. Combined with fibreoptic distribution networks and ultrasensitive detection strategies, compact and portable sensors are now appearing for a variety of applications. In many cases, the superior spectroscopic quality of the new laser sources compared with earlier cryogenic, mid-IR devices is allowing increased sensitivity of trace species measurements, high-precision spectroscopy of major gas constituents, and stable, autonomous measurement systems. The purpose of this article is to review recent progress in this field and suggest likely directions for future research and development. The various laser-source technologies are briefly reviewed as they relate to sensor applications. Basic theory for laser absorption measurements of gas-dynamic properties is reviewed and special detection strategies for the weak near-IR and visible absorption spectra are described. Typical sensor configurations are described and compared for various application scenarios, ranging from laboratory research to automated field and airborne packages. Recent applications of gas-dynamic sensors for air flows and fluxes of trace atmospheric species are presented. Applications of gas-dynamic and combustion sensors to research and development of high-speed flows aeropropulsion engines, and combustion emissions monitoring are presented in detail, along with emerging flow control systems based on these new sensors. Finally, technology in nonlinear frequency conversion, UV laser materials, room-temperature mid-IR materials and broadly tunable multisection devices is reviewed to suggest new sensor possibilities.

Stereoscopic construction and practice of optoelectronic technology textbook

NASA Astrophysics Data System (ADS)

Zhou, Zigang; Zhang, Jinlong; Wang, Huili; Yang, Yongjia; Han, Yanling

2017-08-01

It is a professional degree course textbook for the Nation-class Specialty—Optoelectronic Information Science and Engineering, and it is also an engineering practice textbook for the cultivation of photoelectric excellent engineers. The book seeks to comprehensively introduce the theoretical and applied basis of optoelectronic technology, and it's closely linked to the current development of optoelectronic industry frontier and made up of following core contents, including the laser source, the light's transmission, modulation, detection, imaging and display. At the same time, it also embodies the features of the source of laser, the transmission of the waveguide, the electronic means and the optical processing methods.

Prospects of third-generation femtosecond laser technology in biological spectromicroscopy

NASA Astrophysics Data System (ADS)

Fattahi, Hanieh; Fattahi, Zohreh; Ghorbani, Asghar

2018-05-01

The next generation of biological imaging modalities will be a movement towards super-resolution, label-free approaches to realize subcellular images in a nonperturbative, non-invasive manner and towards new detection metrologies to reach a higher sensitivity and dynamic range. In this paper, we discuss how the third generation femtosecond laser technology in combination with the already existing concepts in time-resolved spectroscopy could fulfill the requirements of these exciting prospects. The expected enhanced specificity and sensitivity of the envisioned super-resolution microscope could lead us to a better understanding of the inter- and intra-cellular molecular transport and DNA-protein interaction.

Recent developments in aircraft protection systems for laser guide star operations

NASA Astrophysics Data System (ADS)

Stomski, Paul J.; Murphy, Thomas W.; Campbell, Randy

2012-07-01

The astronomical community's use of high power laser guide star adaptive optics (LGS-AO) systems presents a potential hazard to aviation. Historically, the most common and trusted means of protecting aircraft and their occupants has been the use of safety observers (aka spotters) armed with shut-off switches. These safety observers watch for aircraft at risk and terminate laser propagation before the aircraft can be adversely affected by the laser. Efforts to develop safer and more cost-effective automated aircraft protection systems for use by the astronomical community have been inhibited by both technological and regulatory challenges. This paper discusses recent developments in these two areas. Specifically, with regard to regulation and guidance we discuss the 2011 release of AS-6029 by the SAE as well as the potential impact of RTCA DO-278A. With regard to the recent developments in the technology used to protect aircraft from laser illumination, we discuss the novel Transponder Based Aircraft Detection (TBAD) system being installed at W. M. Keck Observatory (WMKO). Finally, we discuss our strategy for evaluating TBAD compliance with the regulations and for seeking appropriate approvals for LGS operations at WMKO using a fully automated, flexibly configured, multi-tier aircraft protection system incorporating this new technology.

Optical leak detection of oxygen using IR-laser diodes

NASA Technical Reports Server (NTRS)

Disimile, P. J.; Fox, C.; Toy, N.

1991-01-01

The ability to accurately measure the concentration of gaseous oxygen and its corresponding flow rate is becoming of greater importance. The technique being presented is based on the principal of light attenuation due to the absorption of radiation by the A-band of oxygen which is located in the 759-770 nm wavelength range. With an ability to measure the change in the light transmission to 0.05 percent, a sensitive optical leak detection system which has a rapid time response is possible. In this research program, the application of laser diode technology and its ability to be temperature tuned to a selected oxygen absorption spectral peak has allowed oxygen concentrations as low as 16,000 ppm to be detected.

A review on several key problems of standoff trace explosives detection by optical-related technology

NASA Astrophysics Data System (ADS)

Chen, Zhibin; Xiao, Cheng; Xiao, Wenjian; Qin, Mengze; Liu, Xianhong

2016-01-01

To prevent tragic disasters caused by terror acts and warfare threats, security check personnel must be capable of discovering, distinguishing and eliminating the explosives at multiple circumstances. Standoff technology for the remote detection of explosives and their traces on contaminated surfaces is a research field that has become a heightened priority in recent years for homeland security and counter-terrorism applications. There has been a huge increase in research within this area, the improvement of standoff trace explosives detection by optical-related technology. This paper provides a consolidation of information relating to recent advances in several key problems of, without being limited to one specific research area or explosive type. Working laser wavelength of detection system is discussed. Generation and collection of explosives spectra signal are summarized. Techniques for analysing explosives spectra signal are summed up.

Advances in three-dimensional rapid prototyping of microfluidic devices for biological applications

PubMed Central

O'Neill, P. F.; Ben Azouz, A.; Vázquez, M.; Liu, J.; Marczak, S.; Slouka, Z.; Chang, H. C.; Diamond, D.; Brabazon, D.

2014-01-01

The capability of 3D printing technologies for direct production of complex 3D structures in a single step has recently attracted an ever increasing interest within the field of microfluidics. Recently, ultrafast lasers have also allowed developing new methods for production of internal microfluidic channels within the bulk of glass and polymer materials by direct internal 3D laser writing. This review critically summarizes the latest advances in the production of microfluidic 3D structures by using 3D printing technologies and direct internal 3D laser writing fabrication methods. Current applications of these rapid prototyped microfluidic platforms in biology will be also discussed. These include imaging of cells and living organisms, electrochemical detection of viruses and neurotransmitters, and studies in drug transport and induced-release of adenosine triphosphate from erythrocytes. PMID:25538804

Development of a Laser for Landmine Destruction Final Report CRADA No. TC02126.0

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

Yamamoto, R.; Sheppard, C.

2017-08-31

This was one of two CRADAs between Lawrence Livermore National Security, LLC as manager and operator of Lawrence Livermore National Laboratory (LLNL) and First Alliance Technologies, LLC (First Alliance), to conduct research and development activity toward an integrated system for the detecting, locating, and destroying of landmines and unexploded ordinance using a laser to destroy landmines and unexploded ordinance and First Alliance’s Land Mine Locator (LML) system.

United States Amphibious Forcible Entry: An Expensive Necessity

DTIC Science & Technology

2011-03-17

controversial, Navy EOD teams also operate Marine Mammal Systems (MMS) such as dolphins , sea lions and beluga whales for mine detection and...such as laser weapons, touted as a ―game-changer,‖ are also being researched to counter the anti-ship missile threat.49 As Till noted, ―Throughout...Reported in Navy Laser Weapon Technology,‖ PilotOnline, (Norfolk Virginian-Pilot), 21 January 2011, http://hamptonroads.com (accessed 29 January 2011

Optical spectroscopy of laser-produced plasmas for standoff isotopic analysis

NASA Astrophysics Data System (ADS)

Harilal, S. S.; Brumfield, B. E.; LaHaye, N. L.; Hartig, K. C.; Phillips, M. C.

2018-06-01

Rapid, in-field, and non-contact isotopic analysis of solid materials is extremely important to a large number of applications, such as nuclear nonproliferation monitoring and forensics, geochemistry, archaeology, and biochemistry. Presently, isotopic measurements for these and many other fields are performed in laboratory settings. Rapid, in-field, and non-contact isotopic analysis of solid material is possible with optical spectroscopy tools when combined with laser ablation. Laser ablation generates a transient vapor of any solid material when a powerful laser interacts with a sample of interest. Analysis of atoms, ions, and molecules in a laser-produced plasma using optical spectroscopy tools can provide isotopic information with the advantages of real-time analysis, standoff capability, and no sample preparation requirement. Both emission and absorption spectroscopy methods can be used for isotopic analysis of solid materials. However, applying optical spectroscopy to the measurement of isotope ratios from solid materials presents numerous challenges. Isotope shifts arise primarily due to variation in nuclear charge distribution caused by different numbers of neutrons, but the small proportional nuclear mass differences between nuclei of various isotopes lead to correspondingly small differences in optical transition wavelengths. Along with this, various line broadening mechanisms in laser-produced plasmas and instrumental broadening generated by the detection system are technical challenges frequently encountered with emission-based optical diagnostics. These challenges can be overcome by measuring the isotope shifts associated with the vibronic emission bands from molecules or by using the techniques of laser-based absorption/fluorescence spectroscopy to marginalize the effect of instrumental broadening. Absorption and fluorescence spectroscopy probe the ground state atoms existing in the plasma when it is cooler, which inherently provides narrower lineshapes, as opposed to emission spectroscopy which requires higher plasma temperatures to be able to detect thermally excited emission. Improvements in laser and detection systems and spectroscopic techniques have allowed for isotopic measurements to be carried out at standoff distances under ambient atmospheric conditions, which have expanded the applicability of optical spectroscopy-based isotopic measurements to a variety of scientific fields. These technological advances offer an in-situ measurement capability that was previously not available. This review will focus on isotope detection through emission, absorption, and fluorescence spectroscopy of atoms and molecules in a laser-produced plasma formed from a solid sample. A description of the physics behind isotope shifts in atoms and molecules is presented, followed by the physics behind solid sampling of laser ablation plumes, optical methods for isotope measurements, the suitable physical conditions of laser-produced plasma plumes for isotopic analysis, and the current status. Finally, concluding remarks will be made on the existing knowledge/technological gaps identified from the current literature and suggestions for the future work.

Technologies for security, military police and professional policing organizations, the Department of Energy perspective

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

Steele, B.J.

1996-12-31

There are many technologies emerging from this decade that can be used to help the law enforcement community protect the public as well as public and private facilities against ever increasing threats to this country and its resources. These technologies include sensors, closed circuit television (CCTV), access control, contraband detection, communications, control and display, barriers, and various component and system modeling techniques. This paper will introduce some of the various technologies that have been examined for the Department of Energy that could be applied to various law enforcement applications. They include: (1) scannerless laser radar; (2) next generation security systems;more » (3) response force video information helmet system; (4) access delay technologies; (5) rapidly deployable intrusion detection systems; and (6) cost risk benefit analysis.« less

Quantum Limits of Space-to-Ground Optical Communications

NASA Technical Reports Server (NTRS)

Hemmati, H.; Dolinar, S.

2012-01-01

For a pure loss channel, the ultimate capacity can be achieved with classical coherent states (i.e., ideal laser light): (1) Capacity-achieving receiver (measurement) is yet to be determined. (2) Heterodyne detection approaches the ultimate capacity at high mean photon numbers. (3) Photon-counting approaches the ultimate capacity at low mean photon numbers. A number of current technology limits drive the achievable performance of free-space communication links. Approaching fundamental limits in the bandwidth-limited regime: (1) Heterodyne detection with high-order coherent-state modulation approaches ultimate limits. SOA improvements to laser phase noise, adaptive optics systems for atmospheric transmission would help. (2) High-order intensity modulation and photon-counting can approach heterodyne detection within approximately a factor of 2. This may have advantages over coherent detection in the presence of turbulence. Approaching fundamental limits in the photon-limited regime (1) Low-duty cycle binary coherent-state modulation (OOK, PPM) approaches ultimate limits. SOA improvements to laser extinction ratio, receiver dark noise, jitter, and blocking would help. (2) In some link geometries (near field links) number-state transmission could improve over coherent-state transmission

Research on propane leak detection system and device based on mid infrared laser

NASA Astrophysics Data System (ADS)

Jiang, Meng; Wang, Xuefeng; Wang, Junlong; Wang, Yizhao; Li, Pan; Feng, Qiaoling

2017-10-01

Propane is a key component of liquefied petroleum gas (LPG) and crude oil volatile. This issue summarizes the recent progress of propane detection technology. Meanwhile, base on the development trend, our latest progress is also provided. We demonstrated a mid infrared propane sensor system, which is based on wavelength modulation spectroscopy (WMS) technique with a CW interband cascade laser (ICL) emitting at 3370.4nm. The ICL laser scanned over a sharp feature in the broader spectrum of propane, and harmonic signals are obtained by lock-in amplifier for gas concentration deduction. The surrounding gas is extracted into the fine optical absorption cell through the pump to realize online detection. The absorption cell is designed in mid infrared windows range. An example experimental setup is shown. The second harmonic signals 2f and first harmonic signals1f are obtained. We present the sensor performance test data including dynamic precision and temperature stability. The propane detection sensor system and device is portable can carried on the mobile inspection vehicle platforms or intelligent robot inspection platform to realize the leakage monitoring of whole oil gas tank area.

Commercial-Aircraft Protection System

NASA Astrophysics Data System (ADS)

Case, Russell L., Jr.; Wolff, Peter H.

2004-09-01

Recent world events have identified needs for a commercial aircraft defense system against Man-Portable Air Defense Systems (MANPADS), such as SA-7 and Stinger shoulder launched surface-to-air missiles. Technical challenges include target detection, identification and countermeasures. Political and societal challenges include cost, time to deployment, ground and air safety, and reliability. These challenges, as well as many others, have been met and overcome with the development of Thor Systems' Commercial-Aircraft Protection System (C-APS). C-APS makes use of commercial technology such as radar and infrared sensors with a laser-based countermeasure. Unlike adapted military systems, C-APS detects the threat long before the military versions by employing a 360 degree hemispherical scan, identifying the threat with an infrared sensor and employing a directed laser to not only deflect the target but to permanently disable its seeker. Enhanced capabilities include multiple threat elimination and closed-loop technology for kill verification. All of this is accomplished with development costs less than half that required to convert military technology, manufacturing costs significantly less than competitive products, and a maintenance cycle coincident with standard FAA requirements, which are significantly longer than current systems.

Monitoring forests at the speed of light.

Treesearch

Valerie Rapp

2005-01-01

Airborne laser scanning is a technology developed in the last 15 years. Commonly referred to as light detection and ranging, or LIDAR, these systems can map ground with up to a 6-inch elevation accuracy in open, flat terrain. LIDAR is being rapidly adopted for topographical and flood-plain mapping and the detection of earthquake faults hidden by vegetation, among other...

2-micron Pulsed Direct Detection IPDA Lidar for Atmospheric CO2 Measurements

NASA Astrophysics Data System (ADS)

Yu, J.; Singh, U.; Petros, M.

2012-12-01

A 2-micron high energy, pulsed Integrated Path Differential Absorption (IPDA) lidar is being developed for atmospheric CO2 measurements. Development of this lidar heavily leverages the 2-micron laser technologies developed in LaRC over the last decade. The high pulse energy, direct detection lidar operating at CO2 2-micron absorption band provides an alternate approach to measure CO2 concentrations with significant advantages. It is expected to provide high-precision measurement capability by unambiguously eliminating contamination from aerosols and clouds that can bias the IPDA measurement. Our objective is to integrate an existing high energy double-pulsed 2-micron laser transmitter with a direct detection receiver and telescope to enable an airborne capability to perform a first proof of principle demonstration of airborne direct detection CO2 measurements. The 2-micron transmitter provides 100mJ at 10Hz with double pulse format specifically designed for DIAL/IPDA instrument. The compact, rugged, highly reliable transceiver is based on unique Ho:Tm:YLF high-energy 2-micron pulsed laser technology. All the optical mounts are custom designed and have space heritage. A 16-inch diameter telescope has been designed and being manufactured for the direct detection lidar. The detector is an InGaAs Positive-Intrinsic-Negative (PIN) photodiode manufactured by Hamamatsu Corporation. The performance of the detector is characterized at various operating temperatures and bias voltages for spectral response, NEP, response time, dynamic range, and linearity. A collinear lidar structure is designed to be integrated to NASA UC12 or B200 research aircrafts. This paper will describe the design of the airborne 2-micron pulsed IPDA lidar system; the lidar operation parameters; the wavelength pair selection; laser transmitter energy, pulse rate, beam divergence, double pulse generation and accurate frequency control; detector characterization; telescope design; lidar structure design; and lidar signal to noise ratio estimation. The first engineering flight is scheduled at the end of next year.

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.

Note: Large active area solid state photon counter with 20 ps timing resolution and 60 fs detection delay stability

NASA Astrophysics Data System (ADS)

Prochazka, Ivan; Kodet, Jan; Eckl, Johann; Blazej, Josef

2017-10-01

We are reporting on the design, construction, and performance of a photon counting detector system, which is based on single photon avalanche diode detector technology. This photon counting device has been optimized for very high timing resolution and stability of its detection delay. The foreseen application of this detector is laser ranging of space objects, laser time transfer ground to space and fundamental metrology. The single photon avalanche diode structure, manufactured on silicon using K14 technology, is used as a sensor. The active area of the sensor is circular with 200 μm diameter. Its photon detection probability exceeds 40% in the wavelength range spanning from 500 to 800 nm. The sensor is operated in active quenching and gating mode. A new control circuit was optimized to maintain high timing resolution and detection delay stability. In connection to this circuit, timing resolution of the detector is reaching 20 ps FWHM. In addition, the temperature change of the detection delay is as low as 70 fs/K. As a result, the detection delay stability of the device is exceptional: expressed in the form of time deviation, detection delay stability of better than 60 fs has been achieved. Considering the large active area aperture of the detector, this is, to our knowledge, the best timing performance reported for a solid state photon counting detector so far.

Three-photon fluorescence imaging of melanin with a dual-wedge confocal scanning system

NASA Astrophysics Data System (ADS)

Mega, Yair; Kerimo, Joseph; Robinson, Joseph; Vakili, Ali; Johnson, Nicolette; DiMarzio, Charles

2012-03-01

Confocal microscopy can be used as a practical tool in non-invasive applications in medical diagnostics and evaluation. In particular, it is being used for the early detection of skin cancer to identify pathological cellular components and, potentially, replace conventional biopsies. The detection of melanin and its spatial location and distribution plays a crucial role in the detection and evaluation of skin cancer. Our previous work has shown that the visible emission from melanin is strong and can be easily observed with a near-infrared CW laser using low power. This is due to a unique step-wise, (SW) three-photon excitation of melanin. This paper shows that the same SW, 3-photon fluorescence can also be achieved with an inexpensive, continuous-wave laser using a dual-prism scanning system. This demonstrates that the technology could be integrated into a portable confocal microscope for clinical applications. The results presented here are in agreement with images obtained with the larger and more expensive femtosecond laser system used earlier.

Airborne laser-diode-array illuminator assessment for the night vision's airborne mine-detection arid test

NASA Astrophysics Data System (ADS)

Stetson, Suzanne; Weber, Hadley; Crosby, Frank J.; Tinsley, Kenneth; Kloess, Edmund; Nevis, Andrew J.; Holloway, John H., Jr.; Witherspoon, Ned H.

2004-09-01

The Airborne Littoral Reconnaissance Technologies (ALRT) project has developed and tested a nighttime operational minefield detection capability using commercial off-the-shelf high-power Laser Diode Arrays (LDAs). The Coastal System Station"s ALRT project, under funding from the Office of Naval Research (ONR), has been designing, developing, integrating, and testing commercial arrays using a Cessna airborne platform over the last several years. This has led to the development of the Airborne Laser Diode Array Illuminator wide field-of-view (ALDAI-W) imaging test bed system. The ALRT project tested ALDAI-W at the Army"s Night Vision Lab"s Airborne Mine Detection Arid Test. By participating in Night Vision"s test, ALRT was able to collect initial prototype nighttime operational data using ALDAI-W, showing impressive results and pioneering the way for final test bed demonstration conducted in September 2003. This paper describes the ALDAI-W Arid Test and results, along with processing steps used to generate imagery.

Detrecting and Locating Partial Discharges in Transformers

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

Shourbaji, A.; Richards, R.; Kisner, R. A.

A collaborative research between the Oak Ridge National Laboratory (ORNL), the American Electric Power (AEP), the Tennessee Valley Authority (TVA), and the State of Ohio Energy Office (OEO) has been formed to conduct a feasibility study to detect and locate partial discharges (PDs) inside large transformers. The success of early detection of the PDs is necessary to avoid costly catastrophic failures that can occur if the process of PD is ignored. The detection method under this research is based on an innovative technology developed by ORNL researchers using optical methods to sense the acoustical energy produced by the PDs. ORNLmore » researchers conducted experimental studies to detect PD using an optical fiber as an acoustic sensor capable of detecting acoustical disturbances at any point along its length. This technical approach also has the potential to locate the point at which the PD was sensed within the transformer. Several optical approaches were experimentally investigated, including interferometric detection of acoustical disturbances along the sensing fiber, light detection and ranging (LIDAR) techniques using frequency modulation continuous wave (FMCW), frequency modulated (FM) laser with a multimode fiber, FM laser with a single mode fiber, and amplitude modulated (AM) laser with a multimode fiber. The implementation of the optical fiber-based acoustic measurement technique would include installing a fiber inside a transformer allowing real-time detection of PDs and determining their locations. The fibers are nonconductive and very small (core plus cladding are diameters of 125 μm for single-mode fibers and 230 μm for multimode fibers). The research identified the capabilities and limitations of using optical technology to detect and locate sources of acoustical disturbances such as in PDs in large transformers. Amplitude modulation techniques showed the most promising results and deserve further research to better quantify the technique’s sensitivity and its ability to characterize a PD event. Other sensing techniques have been also identified, such as the wavelength shifting fiber optics and custom fabricated fibers with special coatings.« less

Monolithically Integrated Mid-Infrared Quantum Cascade Laser and Detector

PubMed Central

Schwarz, Benedikt; Reininger, Peter; Detz, Hermann; Zederbauer, Tobias; Andrews, Aaron Maxwell; Schrenk, Werner; Strasser, Gottfried

2013-01-01

We demonstrate the monolithic integration of a mid-infrared laser and detector utilizing a bi-functional quantum cascade active region. When biased, this active region provides optical gain, while it can be used as a detector at zero bias. With our novel approach we can measure the light intensity of the laser on the same chip without the need of external lenses or detectors. Based on a bound-to-continuum design, the bi-functional active region has an inherent broad electro-luminescence spectrum of 200 cm−1, which indicate sits use for single mode laser arrays. We have measured a peak signal of 191.5 mV at theon-chip detector, without any amplification. The room-temperature pulsed emission with an averaged power consumption of 4 mW and the high-speed detection makes these devices ideal for low-power sensors. The combination of the on-chip detection functionality, the broad emission spectrum and the low average power consumption indicates the potential of our bi-functional quantum cascade structures to build a mid-infrared lab-on-a-chip based on quantum cascade laser technology. PMID:23389348

Remote laser drilling and sampling system for the detection of concealed explosives

NASA Astrophysics Data System (ADS)

Wild, D.; Pschyklenk, L.; Theiß, C.; Holl, G.

2017-05-01

The detection of hazardous materials like explosives is a central issue in national security in the field of counterterrorism. One major task includes the development of new methods and sensor systems for the detection. Many existing remote or standoff methods like infrared or raman spectroscopy find their limits, if the hazardous material is concealed in an object. Imaging technologies using x-ray or terahertz radiation usually yield no information about the chemical content itself. However, the exact knowledge of the real threat potential of a suspicious object is crucial for disarming the device. A new approach deals with a laser drilling and sampling system for the use as verification detector for suspicious objects. Central part of the system is a miniaturised, diode pumped Nd:YAG laser oscillator-amplifier. The system allows drilling into most materials like metals, synthetics or textiles with bore hole diameters in the micron scale. During the drilling process, the hazardous material can be sampled for further investigation with suitable detection methods. In the reported work, laser induced breakdown spectroscopy (LIBS) is used to monitor the drilling process and to classify the drilled material. Also experiments were carried out to show the system's ability to not ignite even sensitive explosives like triacetone triperoxide (TATP). The detection of concealed hazardous material is shown for different explosives using liquid chromatography and ion mobility spectrometry.

Laser optoacoustic tomography for medical diagnostics: principles

NASA Astrophysics Data System (ADS)

Oraevsky, Alexander A.; Esenaliev, Rinat O.; Jacques, Steven L.; Tittel, Frank K.

1996-04-01

This paper is to describe principles of laser optoacoustic tomography for medical diagnostics. Two types of imaging modes are presented. The first is the tomography in transmission mode, which utilizes detection of stress transients transmitted from the laser-excited volume toward the depth through thick layers of tissue. The second is the tomography in reflection mode which utilizes detection of stress transients generated in superficial tissue layer and reflected back toward tissue surface. To distinguish the two modes, we have abbreviated them as (1) laser optoacoustic tomography in transmission mode, LOATT, and (2) time-resolved stress detection tomography of light absorption, TRSDTLA, in reflection mode where emphasis is made on high spatial resolution of images. The basis for laser optoacoustic tomography is the time-resolved detection of laser-induced transient stress waves, selectively generated in absorbing tissues of diagnostic interest. Such a technique allows one to visualize absorbed light distribution in turbid biological tissues irradiated by short laser pulses. Laser optoacoustic tomography can be used for detection of tissue pathological changes that result in either increased concentration of various tissue chromophores such as hemoglobin or in development of enhanced microcirculation in diseased tissue. Potential areas of applications are diagnosis of cancer, brain hemorrhages, arterial atherosclerotic plaques, and other diseased tissues. In addition, it can provide feedback information during medical treatments. Both LOATT and TRSDTLA utilize laser excitation of biological tissues and sensitive detection of laser-induced stress waves. Optical selectivity is based upon differences in optical properties of pathologically different tissues. Sensitivity comes from stress generation under irradiation conditions of temporal stress confinement. The use of sensitive wide-band lithium niobate acoustic transducers expands limits of laser optoacoustic tomography. The technology allows us to determine directly temperature distributions in tissues and locate tissues volumes with different absorption. To demonstrate principles of TRSDTLA, experiments were conducted in vivo with mice-model for breast cancer using specially designed front-surface transducers- reflectometers. To present advantages and limitation of LOATT, experiments were performed in phantoms made of gel with polystyrene spheres colored with copper sulfate. Our experimental results and theoretical calculations show that TRSDTLA can be applied for non- invasive histology of layered tissues with in-depth resolution of up to 2 microns. TRSDTLA in acoustic reflection mode is promising for diagnostics of skin and ocular diseases. LOATT in acoustic transmission mode can be applied for detection of small tissue volumes with enhanced absorption located inside organs at the depth of up to 10 cm.

Active mode locking of quantum cascade lasers in an external ring cavity.

PubMed

Revin, D G; Hemingway, M; Wang, Y; Cockburn, J W; Belyanin, A

2016-05-05

Stable ultrashort light pulses and frequency combs generated by mode-locked lasers have many important applications including high-resolution spectroscopy, fast chemical detection and identification, studies of ultrafast processes, and laser metrology. While compact mode-locked lasers emitting in the visible and near infrared range have revolutionized photonic technologies, the systems operating in the mid-infrared range where most gases have their strong absorption lines, are bulky and expensive and rely on nonlinear frequency down-conversion. Quantum cascade lasers are the most powerful and versatile compact light sources in the mid-infrared range, yet achieving their mode-locked operation remains a challenge, despite dedicated effort. Here we report the demonstration of active mode locking of an external-cavity quantum cascade laser. The laser operates in the mode-locked regime at room temperature and over the full dynamic range of injection currents.

Active mode locking of quantum cascade lasers in an external ring cavity

PubMed Central

Revin, D. G.; Hemingway, M.; Wang, Y.; Cockburn, J. W.; Belyanin, A.

2016-01-01

Stable ultrashort light pulses and frequency combs generated by mode-locked lasers have many important applications including high-resolution spectroscopy, fast chemical detection and identification, studies of ultrafast processes, and laser metrology. While compact mode-locked lasers emitting in the visible and near infrared range have revolutionized photonic technologies, the systems operating in the mid-infrared range where most gases have their strong absorption lines, are bulky and expensive and rely on nonlinear frequency down-conversion. Quantum cascade lasers are the most powerful and versatile compact light sources in the mid-infrared range, yet achieving their mode-locked operation remains a challenge, despite dedicated effort. Here we report the demonstration of active mode locking of an external-cavity quantum cascade laser. The laser operates in the mode-locked regime at room temperature and over the full dynamic range of injection currents. PMID:27147409

Analysis of detection performance of multi band laser beam analyzer

NASA Astrophysics Data System (ADS)

Du, Baolin; Chen, Xiaomei; Hu, Leili

2017-10-01

Compared with microwave radar, Laser radar has high resolution, strong anti-interference ability and good hiding ability, so it becomes the focus of laser technology engineering application. A large scale Laser radar cross section (LRCS) measurement system is designed and experimentally tested. First, the boundary conditions are measured and the long range laser echo power is estimated according to the actual requirements. The estimation results show that the echo power is greater than the detector's response power. Secondly, a large scale LRCS measurement system is designed according to the demonstration and estimation. The system mainly consists of laser shaping, beam emitting device, laser echo receiving device and integrated control device. Finally, according to the designed lidar cross section measurement system, the scattering cross section of target is simulated and tested. The simulation results are basically the same as the test results, and the correctness of the system is proved.

Measurements of CO, CO2, OH, and H2O in room-temperature and combustion gases by use of a broadly current-tuned multisection InGaAsP diode laser.

PubMed

Upschulte, B L; Sonnenfroh, D M; Allen, M G

1999-03-20

A new laser technology that achieves nearly 100-nm quasi-continuous tuning with only injection-current control in a four-section grating-coupler sampled-reflector laser was used to detect CO and CO(2) simultaneously in room-temperature gas mixtures. The same grating-coupler sampled-reflector laser was used to perform in situ measurements of CO, H(2)O, and OH in the exhaust gases of a CH(4)-air flame. This laser is being evaluated for inclusion in a multispecies combustion-emissions exhaust-analysis sensor, and its operational characteristics as they have an impact on gas sensing are described. Preliminary results suggest that this single laser can be used to replace multilaser sensor configurations for some combustion-emissions monitoring applications.

Standoff detection of explosive substances at distances of up to 150 m.

PubMed

Mukherjee, Anadi; Von der Porten, Steven; Patel, C Kumar N

2010-04-10

We report detection and identification of trace quantities of explosives at standoff distances up to 150 m with high sensitivity (signal-to-noise ratio of approximately 70) and high selectivity. The technique involves illuminating the target object with laser radiation at a wavelength that is strongly absorbed by the target. The resulting temperature rise is observed by remotely monitoring the increased blackbody radiation from the sample. An unambiguous determination of the target, TNT, in soil samples collected from an explosives test site in China Lake Naval Air Weapons Station is achieved through the use of a tunable CO(2) laser that scans over the absorption fingerprint of the target explosives. The theoretical analysis supports the observation and indicates that, with optimized detectors and data processing algorithms, the measurement capability can be improved significantly, permitting rapid standoff detection of explosives at distances approaching 1 km. The detection sensitivity varies as R(-2) and, thus, with the availability of high power, room-temperature, tunable mid-wave infrared and long-wave infrared quantum cascade lasers, this technology may play an important role in screening personnel and their belongings at short distances, such as in airports, for detecting and identifying explosives material residue on persons.

DEMONSTRATION BULLETIN: RAPID OPTICAL SCREEN TOOL (ROST™) - LORAL CORPORATION

EPA Science Inventory

The Loral Rapid Optical Screen Tool (ROST™) is a tunable dye laser system used for the detection of petroleum, semi-volatile, and some volatile organic compounds in soils. The technology is used in conjunction with a cone penetrometer (CP).

Continuous section extraction and over-underbreak detection of tunnel based on 3D laser technology and image analysis

NASA Astrophysics Data System (ADS)

Wang, Weixing; Wang, Zhiwei; Han, Ya; Li, Shuang; Zhang, Xin

2015-03-01

In order to ensure safety, long term stability and quality control in modern tunneling operations, the acquisition of geotechnical information about encountered rock conditions and detailed installed support information is required. The limited space and time in an operational tunnel environment make the acquiring data challenging. The laser scanning in a tunneling environment, however, shows a great potential. The surveying and mapping of tunnels are crucial for the optimal use after construction and in routine inspections. Most of these applications focus on the geometric information of the tunnels extracted from the laser scanning data. There are two kinds of applications widely discussed: deformation measurement and feature extraction. The traditional deformation measurement in an underground environment is performed with a series of permanent control points installed around the profile of an excavation, which is unsuitable for a global consideration of the investigated area. Using laser scanning for deformation analysis provides many benefits as compared to traditional monitoring techniques. The change in profile is able to be fully characterized and the areas of the anomalous movement can easily be separated from overall trends due to the high density of the point cloud data. Furthermore, monitoring with a laser scanner does not require the permanent installation of control points, therefore the monitoring can be completed more quickly after excavation, and the scanning is non-contact, hence, no damage is done during the installation of temporary control points. The main drawback of using the laser scanning for deformation monitoring is that the point accuracy of the original data is generally the same magnitude as the smallest level of deformations that are to be measured. To overcome this, statistical techniques and three dimensional image processing techniques for the point clouds must be developed. For safely, effectively and easily control the problem of Over Underbreak detection of road and solve the problemof the roadway data collection difficulties, this paper presents a new method of continuous section extraction and Over Underbreak detection of road based on 3D laser scanning technology and image processing, the method is divided into the following three steps: based on Canny edge detection, local axis fitting, continuous extraction section and Over Underbreak detection of section. First, after Canny edge detection, take the least-squares curve fitting method to achieve partial fitting in axis. Then adjust the attitude of local roadway that makes the axis of the roadway be consistent with the direction of the extraction reference, and extract section along the reference direction. Finally, we compare the actual cross-sectional view and the cross-sectional design to complete Overbreak detected. Experimental results show that the proposed method have a great advantage in computing costs and ensure cross-section orthogonal intercept terms compared with traditional detection methods.

Development of gas fire detection system using tunable diode laser absorption spectroscopy

NASA Astrophysics Data System (ADS)

Jiang, Y. L.; Li, G.; Yang, T.; Wang, J. J.

2017-01-01

The conventional fire detection methods mainly produce an alarm through detecting the changes in smoke concentration, flame radiation, heat and other physical parameters in the environment, but are unable to provide an early warning of a fire emergency. We have designed a gas fire detection system with a high detection sensitivity and high selectivity using the tunable semiconductor diode laser as a light source and combining wavelength modulation and harmonic detection technology. This system can invert the second harmonic signal obtained to obtain the concentration of carbon monoxide gas (a fire characteristic gas) so as to provide an early warning of fire. We reduce the system offset noise and the background noise generated due to the laser interference by deducting the system background spectrum lines from the second harmonic signal. This can also eliminate the interference of other gas spectral lines to a large extent. We detected the concentration of the carbon monoxide gas generated in smoldering sandalwood fire and open beech wood fire with the homemade fire simulator, and tested the lowest detectable limit of system. The test results show that the lowest detectable limit can reach 5×10-6 the system can maintain stable operation for a long period of time and can automatically trigger a water mist fire extinguishing system, which can fully meet the needs of early fire warning.

Standoff detection of explosives: a challenging approach for optical technologies

NASA Astrophysics Data System (ADS)

Désilets, S.; Hô, N.; Mathieu, P.; Simard, J. R.; Puckrin, E.; Thériault, J. M.; Lavoie, H.; Théberge, F.; Babin, F.; Gay, D.; Forest, R.; Maheux, J.; Roy, G.; Châteauneuf, M.

2011-06-01

Standoff detection of explosives residues on surfaces at few meters was made using optical technologies based on Raman scattering, Laser-Induced Breakdown Spectroscopy (LIBS) and passive standoff FTIR radiometry. By comparison, detection and analysis of nanogram samples of different explosives was made with a microscope system where Raman scattering from a micron-size single point illuminated crystal of explosive was observed. Results from standoff detection experiments using a telescope were compared to experiments using a microscope to find out important parameters leading to the detection. While detection and spectral identification of the micron-size explosive particles was possible with a microscope, standoff detection of these particles was very challenging due to undesired light reflected and produced by the background surface or light coming from other contaminants. Results illustrated the challenging approach of detecting at a standoff distance the presence of low amount of micron or submicron explosive particles.

Demystifying LiDAR technologies for temperate rainforest in the Pacific Northwest

Treesearch

Rhonda Mazza; Demetrios Gatziolis

2013-01-01

Light detection and ranging (LiDAR), also known as airborne laser scanning, is a rapidly emerging technology for remote sensing. Used to help map, monitor, and assess natural resources, LiDAR data were first embraced by forestry professionals in Scandinavia as a tool for conducting forest inventories in the mid to late 1990s. Thus early LiDAR theory and applications...

Assessment of laser-induced acceleration effects in optical clearing of in vivo human skin by optical coherence tomography

NASA Astrophysics Data System (ADS)

Zhan, Zhigang; Wei, Huajiang; Jin, Ying

2015-02-01

Laser irradiation is considered to be a promising innovative technology which has been developed in an attempt to increase transdermal drug delivery. In this study, a near-infrared CW diode laser (785 nm) was applied to increase permeability of glycerol solutions in human skin in vivo and improve the optical clearing efficacy. Results show that for both 15%v/v and 30%v/v glycerol, the permeability coefficient increased significantly if the detected area of the skin tissue was treated with laser irradiation before optical clearing agents (OCAs) were applied. This study based on optical coherence tomography imaging technique and optical clearing effect finds laser irradiation a new approach for enhancing the penetration of OCAs and accelerating the rate of transdermal drug delivery.

[Infrared spectroscopy based on quantum cascade lasers].

PubMed

Wen, Zhong-Quan; Chen, Gang; Peng, Chen; Yuan, Wei-Qing

2013-04-01

Quantum cascade lasers (QCLs) are promising infrared coherent sources. Thanks to the quantum theory and band-gap engineering, QCL can access the wavelength in the range from 3 to 100 microm. Since the fingerprint spectrum of most gases are located in the mid-infrared range, mid-infrared quantum cascade laser based gas sensing technique has become the research focus world wide because of its high power, narrow linewidth and fast scanning. Recent progress in the QCL technology leads to a great improvement in laser output power and efficiency, which stimulates a fast development in the infrared laser spectroscopy. The present paper gives a broad review on the QCL based spectroscopy techniques according to their working principles. A discussion on their applications in gas sensing and explosive detecting is also given at the end of the paper.

PHARAO space atomic clock: new developments on the laser source

NASA Astrophysics Data System (ADS)

Saccoccio, Muriel; Loesel, Jacques; Coatantiec, Claude; Simon, Eric; Laurent, Philippe; Lemonde, Pierre; Maksimovic, I.; Abgrall, M.

2017-11-01

The PHARAO project purpose is to open the way for a new atomic clock generation in space, where laser cooling techniques and microgravity allow high frequency stability and accuracy. The French space agency, CNES is funding and managing the clock construction. The French SYRTE and LKB laboratories are scientific and technical advisers for the clock requirements and the follow-up of subsystem development in industrial companies. EADS SODERN is developing two main subsystems of the PHARAO clock: the Laser Source and the Cesium Tube where atoms are cooled, launched, selected and detected by laser beams. The Laser Source includes an optical bench and electronic devices to generate the laser beams required. This paper describes PHARAO and the role laser beams play in its principle of operation. Then we present the Laser Source design, the technologies involved, and the status of development. Lastly, we focus of a key equipment to reach the performances expected, which is the Extended Cavity Laser Diode.

High Power Laser Diode Arrays for 2-Micron Solid State Coherent Lidars Applications

NASA Technical Reports Server (NTRS)

Amzajerdian, Farzin; Meadows, Byron; Kavaya, Michael J.; Singh, Upendra; Sudesh, Vikas; Baker, Nathaniel

2003-01-01

Laser diode arrays are critical components of any diode-pumped solid state laser systems, constraining their performance and reliability. Laser diode arrays (LDAs) are used as the pump source for energizing the solid state lasing media to generate an intense coherent laser beam with a high spatial and spectral quality. The solid state laser design and the characteristics of its lasing materials define the operating wavelength, pulse duration, and power of the laser diodes. The pump requirements for high pulse energy 2-micron solid state lasers are substantially different from those of more widely used 1-micron lasers and in many aspects more challenging [1]. Furthermore, the reliability and lifetime demanded by many coherent lidar applications, such as global wind profiling from space and long-range clear air turbulence detection from aircraft, are beyond the capability of currently available LDAs. In addition to the need for more reliable LDAs with longer lifetime, further improvement in the operational parameters of high power quasi-cw LDAs, such as electrical efficiency, brightness, and duty cycle, are also necessary for developing cost-effective 2-micron coherent lidar systems for applications that impose stringent size, heat dissipation, and power constraints. Global wind sounding from space is one of such applications, which is the main driver for this work as part of NASA s Laser Risk Reduction Program. This paper discusses the current state of the 792 nm LDA technology and the technology areas being pursued toward improving their performance. The design and development of a unique characterization facility for addressing the specific issues associated with the LDAs for pumping 2-micron coherent lidar transmitters and identifying areas of technological improvement will be described. Finally, the results of measurements to date on various standard laser diode packages, as well as custom-designed packages with potentially longer lifetime, will be reported.

Design and Performance of a Miniature Lidar Wind Profiler (MLWP)

NASA Technical Reports Server (NTRS)

Cornwell, Donald M., Jr.; Miodek, Mariusz J.

1998-01-01

The directional velocity of the wind is one of the most critical components for understanding meteorological and other dynamic atmospheric processes. Altitude-resolved wind velocity measurements, also known as wind profiles or soundings, are especially necessary for providing data for meteorological forecasting and overall global circulation models (GCM's). Wind profiler data are also critical in identifying possible dangerous weather conditions for aviation. Furthermore, a system has yet to be developed for wind profiling from the surface of Mars which could also meet the stringent requirements on size, weight, and power of such a mission. Obviously, a novel wind profiling approach based on small and efficient technology is required to meet these needs. A lidar system based on small and highly efficient semiconductor lasers is now feasible due to recent developments in the laser and detector technologies. The recent development of high detection efficiency (50%), silicon-based photon-counting detectors when combined with high laser pulse repetition rates and long receiver integration times has allowed these transmitter energies to be reduced to the order of microjoules per pulse. Aerosol lidar systems using this technique have been demonstrated for both Q-switched, diode-pumped solid-state laser transmitters (lambda = 523 nm) and semiconductor diode lasers (lambda = 830 nm); however, a wind profiling lidar based on this technique has yet to be developed. We will present an investigation of a semiconductor-laser-based lidar system which uses the "edge-filter" direct detection technique to infer Doppler frequency shifts of signals backscattered from aerosols in the planetary boundary layer (PBL). Our investigation will incorporate a novel semiconductor laser design which mitigates the deleterious effects of frequency chirp in pulsed diode lasers, a problem which has limited their use in such systems in the past. Our miniature lidar could be used on a future Mars lander and perhaps find its own niche in terrestrial applications due to its potential low cost an small size.

System Model for MEMS based Laser Ultrasonic Receiver

NASA Technical Reports Server (NTRS)

Wilson, William C.

2002-01-01

A need has been identified for more advanced nondestructive Evaluation technologies for assuring the integrity of airframe structures, wiring, etc. Laser ultrasonic inspection instruments have been shown to detect flaws in structures. However, these instruments are generally too bulky to be used in the confined spaces that are typical of aerospace vehicles. Microsystems technology is one key to reducing the size of current instruments and enabling increased inspection coverage in areas that were previously inaccessible due to instrument size and weight. This paper investigates the system modeling of a Micro OptoElectroMechanical System (MOEMS) based laser ultrasonic receiver. The system model is constructed in software using MATLAB s dynamical simulator, Simulink. The optical components are modeled using geometrical matrix methods and include some image processing. The system model includes a test bench which simulates input stimuli and models the behavior of the material under test.

Advances in solid state laser technology for space and medical applications

NASA Technical Reports Server (NTRS)

Byvik, C. E.; Buoncristiani, A. M.

1988-01-01

Recent developments in laser technology and their potential for medical applications are discussed. Gas discharge lasers, dye lasers, excimer lasers, Nd:YAG lasers, HF and DF lasers, and other commonly used lasers are briefly addressed. Emerging laser technology is examined, including diode-pumped lasers and other solid state lasers.

Study on feasibility of laser reflective tomography with satellite-accompany

NASA Astrophysics Data System (ADS)

Gu, Yu; Hu, Yi-hua; Hao, Shi-qi; Gu, You-lin; Zhao, Nan-xiang; Wang, Yang-yang

2015-10-01

Laser reflective tomography is a long-range, high-resolution active detection technology, whose advantage is that the spatial resolution is unrelated with the imaging distance. Accompany satellite is a specific satellite around the target spacecraft with encircling movement. When using the accompany satellite to detect the target aircraft, multi-angle echo data can be obtained with the application of reflective tomography imaging. The feasibility of such detection working mode was studied in this article. Accompany orbit model was established with horizontal circular fleet and the parameters of accompany flight was defined. The simulation of satellite-to-satellite reflective tomography imaging with satellite-accompany was carried out. The operating mode of reflective tomographic data acquisition from monostatic laser radar was discussed and designed. The flight period, which equals to the all direction received data consuming time, is one of the important accompany flight parameters. The azimuth angle determines the plane of image formation while the elevation angle determines the projection direction. Both of the azimuth and elevation angles guide the satellite attitude stability controller in order to point the laser radar spot on the target. The influences of distance between accompany satellite and target satellite on tomographic imaging consuming time was analyzed. The influences of flight period, azimuth angle and elevation angle on tomographic imaging were analyzed as well. Simulation results showed that the satellite-accompany laser reflective tomography is a feasible and effective method to the satellite-to-satellite detection.

Laser Technology.

ERIC Educational Resources Information Center

Gauger, Robert

1993-01-01

Describes lasers and indicates that learning about laser technology and creating laser technology activities are among the teacher enhancement processes needed to strengthen technology education. (JOW)

TScan : stationary LiDAR for traffic and safety studies : object detection and tracking.

DOT National Transportation Integrated Search

2016-08-01

The ability to accurately measure and cost-effectively collect traffic data at road intersections is needed to improve their safety and operations. This study investigates the feasibility of using laser ranging technology (LiDAR) for this purpose. Th...

The technology of grating laser Doppler velocimeter for measuring transverse velocity of objects

NASA Astrophysics Data System (ADS)

Zhang, Shu; Lu, Guangfeng; Fan, Zhenfang; Luo, Hui

2014-12-01

In order to lower production cost of Laser Doppler velocimeter (LDV) and simplify the system structure, a grating Doppler detection system has been designed. This LDV was carried out by differential measurement mode. Two beams of diffracted light from the grating are mixed, and the beat frequency will be detected by a detector when the grating is moving. Fundamentals also have been introduced and partial experiment results of this system are given out. The result indicates the experimental value is agreement with the theoretical value. Errors have been analyzed and the main factors affecting the accuracy were discussed. Upon inspection, the inexpensive and ease LDV is efficient to administer and feasible.

NASA Hydrogen Research for Spaceport and Space Based Applications

NASA Technical Reports Server (NTRS)

Anderson, Tim

2006-01-01

The activities presented are a broad based approach to advancing key hydrogen related technologies in areas such as hydrogen production, distributed sensors for hydrogen-leak detection, laser instrumentation for hydrogen-leak detection, and cryogenic transport and storage. Presented are the results form 15 research projects, education, and outreach activities, system and trade studies, and project management. The work will aid in advancing the state-of-the-art for several critical technologies related to the implementation of a hydrogen infrastructure. Activities conducted are relevant to a number of propulsion and power systems for terrestrial, aeronautics, and aerospace applications.

Study on the high-frequency laser measurement of slot surface difference

NASA Astrophysics Data System (ADS)

Bing, Jia; Lv, Qiongying; Cao, Guohua

2017-10-01

In view of the measurement of the slot surface difference in the large-scale mechanical assembly process, Based on high frequency laser scanning technology and laser detection imaging principle, This paragraph designs a double galvanometer pulse laser scanning system. Laser probe scanning system architecture consists of three parts: laser ranging part, mechanical scanning part, data acquisition and processing part. The part of laser range uses high-frequency laser range finder to measure the distance information of the target shape and get a lot of point cloud data. Mechanical scanning part includes high-speed rotary table, high-speed transit and related structure design, in order to realize the whole system should be carried out in accordance with the design of scanning path on the target three-dimensional laser scanning. Data processing part mainly by FPGA hardware with LAbVIEW software to design a core, to process the point cloud data collected by the laser range finder at the high-speed and fitting calculation of point cloud data, to establish a three-dimensional model of the target, so laser scanning imaging is realized.

Constant peak-power single-frequency linearly-polarized all-fiber laser for coherent detection based on closed-loop feedback technology

NASA Astrophysics Data System (ADS)

Ding, Yaqian; Zhang, Xiang; Li, Dong; Wang, Dapeng; Zhang, Renzhong; Song, Chengying; Che, Haozhao; Wang, Rui; Guo, Baoling; Chen, Guanghui

2015-10-01

In this paper, a practical single-frequency high-repetition linearly-polarized eye-safe all-fiber laser with constant peak power is demonstrated. It is based on master-oscillator power amplifier (MOPA) system. A distributed feedback laser diode simulating at 1550nm with narrow linewidth of 2.3 kHz is employed as the seed source. It is modulated to a pulse laser with high repetition of 20 kHz and peak power of 10mW by an acousto-optic modulator (AOM). The pulse width is tunable between 100ns to 400ns. Two-stage cascade amplifier is established, which consists of a pre-amplifier and a power-amplifier. Amplified spontaneous emission (ASE) and stimulated billion scattering are well suppressed by special management. The output peak power of 30W is obtained, which has nearly diffraction-limited beam quality. It operates in linewidth of 1.2MHz, polarization-extinction ratio (PER) of 25dB and signal-to-noise ratio (SNR) of more than 40dB. Gain of the whole amplifier achieves nearly 35dB. Furthermore, an embedded control system (ECS) based on the WinCE operating system (OS) and the chip of S3C2440 is proposed. This control system based on closed-loop feedback technology makes the peak power keeping constant even the pulse width tunable, which is convenient for the end user of the radar. This robust portable laser is remarkable and fulfills the desire of coherent detection excellently.

New serum biomarkers for detection of tuberculosis using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry.

PubMed

Liu, Ji-Yan; Jin, Lei; Zhao, Meng-Yuan; Zhang, Xin; Liu, Chi-Bo; Zhang, Yu-Xiang; Li, Fu-Jian; Zhou, Jian-Min; Wang, Hua-Jun; Li, Ji-Cheng

2011-10-01

New technologies for the early detection of tuberculosis (TB) are urgently needed. Pathological changes within an organ might be reflected in proteomic patterns in serum. The aim of the present study was to screen for the potential protein biomarkers in serum for the diagnosis of TB using proteomic fingerprint technology. Proteomic fingerprint technology combining protein chips with surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) was used to profile the serum proteins from 50 patients with TB, 25 patients with lung disease other than TB, and 25 healthy volunteers. The protein fingerprint expression of all the serum samples and the resulting profiles between TB and control groups were analyzed with the Biomarker Wizard system. A total of 30 discriminating m/z peaks were detected that were related to TB (p<0.01). The model of biomarkers constructed by the Biomarker Patterns Software based on the three biomarkers (2024, 8007, and 8598 Da) generated excellent separation between the TB and control groups. The sensitivity was 84.0% and the specificity was 86.0%. Blind test data indicated a sensitivity of 80.0% and a specificity of 84.2%. The data suggested a potential application of SELDI-TOF MS as an effective technology to profile serum proteome, and with pattern analysis, a diagnostic model comprising three potential biomarkers was indicated to differentiate people with TB and healthy controls rapidly and precisely.

Vacuum birefringence detection in all-optical scenarios

NASA Astrophysics Data System (ADS)

Ataman, Stefan

2018-06-01

In this paper we propose an all-optical vacuum birefringence experiment and evaluate its feasibility for various scenarios. Many petawatt-class lasers became operational and many more are expected to enter operation in the near future, therefore unprecedented electromagnetic fields (EL˜1014-1015 V/m and intensities IL˜1021-1023W/cm 2 ) will become available for experiments. In our proposal a petawatt-class laser disturbs the quantum vacuum and creates a delay in a counterpropagating probe laser beam. Placing this delayed beam in one arm of a Mach-Zehnder interferometer (MZI), allows the measurement of the vacuum refraction coefficient via a phase shift. Coherent as well as squeezed light are both considered and the minimum phase sensitivity evaluated. We show that using existing technology with some moderately optimistic assumptions, at least part of the discussed scenarios are feasible for a vacuum birefringence detection experiment.

Analysis on laser plasma emission for characterization of colloids by video-based computer program

NASA Astrophysics Data System (ADS)

Putri, Kirana Yuniati; Lumbantoruan, Hendra Damos; Isnaeni

2016-02-01

Laser-induced breakdown detection (LIBD) is a sensitive technique for characterization of colloids with small size and low concentration. There are two types of detection, optical and acoustic. Optical LIBD employs CCD camera to capture the plasma emission and uses the information to quantify the colloids. This technique requires sophisticated technology which is often pricey. In order to build a simple, home-made LIBD system, a dedicated computer program based on MATLAB™ for analyzing laser plasma emission was developed. The analysis was conducted by counting the number of plasma emissions (breakdowns) during a certain period of time. Breakdown probability provided information on colloid size and concentration. Validation experiment showed that the computer program performed well on analyzing the plasma emissions. Optical LIBD has A graphical user interface (GUI) was also developed to make the program more user-friendly.

MS Detectors

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

Koppenaal, David W.; Barinaga, Charles J.; Denton, M Bonner B.

2005-11-01

Good eyesight is often taken for granted, a situation that everyone appreciates once vision begins to fade with age. New eyeglasses or contact lenses are traditional ways to improve vision, but recent new technology, i.e. LASIK laser eye surgery, provides a new and exciting means for marked vision restoration and improvement. In mass spectrometry, detectors are the 'eyes' of the MS instrument. These 'eyes' have also been taken for granted. New detectors and new technologies are likewise needed to correct, improve, and extend ion detection and hence, our 'chemical vision'. The purpose of this report is to review and assessmore » current MS detector technology and to provide a glimpse towards future detector technologies. It is hoped that the report will also serve to motivate interest, prompt ideas, and inspire new visions for ion detection research.« less

Structural characterization on in vitro porcine skin treated by ablative fractional laser using optical coherence tomography

NASA Astrophysics Data System (ADS)

Feng, Kairui; Zhou, Kanheng; Ling, Yuting; O'Mahoney, Paul; Ewan, Eadie; Ibbotson, Sally H.; Li, Chunhui; Huang, Zhihong

2018-02-01

Ablative fractional skin laser is widely applied for various skin conditions, especially for cosmetic repairing and promoting the located drug delivery. Although the influence of laser treatment over the skin has been explored before in means of excision and biopsy with microscopy, these approaches are invasive, only morphological and capable of distorting the skin. In this paper the authors use fresh porcine skin samples irradiated by the lasers, followed by detected by using Optical Coherence Tomography (OCT). This advanced optical technique has the ability to present the high resolution structure image of treated sample. The results shows that laser beams can produce holes left on the surface after the irradiation. The depth of holes can be affected by changes of laser energy while the diameter of holes have no corresponding relation. Plus, OCT, as a valuable imaging technology, is capable of monitoring the clinical therapy procedure and assisting the calibration.

High Accuracy Verification of a Correlated-Photon-Based Method for Determining Photon-Counting Detection Efficiency

DTIC Science & Technology

2007-01-01

Metrology; (270.5290) Photon statistics. References and links 1. W. H. Louisell, A. Yariv, and A. E. Siegman , “Quantum Fluctuations and Noise in...939–941 (1981). 7. S. R. Bowman, Y. H. Shih, and C. O. Alley, “The use of Geiger mode avalanche photodiodes for precise laser ranging at very low...light levels: An experimental evaluation”, in Laser Radar Technology and Applications I, James M. Cruickshank, Robert C. Harney eds., Proc. SPIE 663

The research of PSD location method in micro laser welding fields

NASA Astrophysics Data System (ADS)

Zhang, Qiue; Zhang, Rong; Dong, Hua

2010-11-01

In the field of micro laser welding, besides the special requirement in the parameter of lasers, the locating in welding points accurately is very important. The article adopt position sensitive detector (PSD) as hard core, combine optic system, electric circuits and PC and software processing, confirm the location of welding points. The signal detection circuits adopt the special integrate circuit H-2476 to process weak signal. It is an integrated circuit for high-speed, high-sensitivity optical range finding, which has stronger noiseproof feature, combine digital filter arithmetic, carry out repair the any non-ideal factors, increasing the measure precision. The amplifier adopt programmable amplifier LTC6915. The system adapt two dimension stepping motor drive the workbench, computer and corresponding software processing, make sure the location of spot weld. According to different workpieces to design the clamps. The system on-line detect PSD 's output signal in the moving processing. At the workbench moves in the X direction, the filaments offset is detected dynamic. Analyze the X axes moving sampling signal direction could be estimate the Y axes moving direction, and regulate the Y axes moving values. The workbench driver adopt A3979, it is a stepping motor driver with insert transducer and operate easily. It adapts the requirement of location in micro laser welding fields, real-time control to adjust by computer. It can be content up 20 μm's laser micro welding requirement on the whole. Using laser powder cladding technology achieve inter-penetration welding of high quality and reliability.

2005 6th Annual Science and Engineering Technology Conference

DTIC Science & Technology

2005-04-21

BioFAC VBAIDS Hybrid: PCR/Immuno Fast PCR Fast Immunoassay Mass Spec (Pyrolysis) SIBS UV -LIF IR Fluorochrome Charge Detect. BioCADS Trigger Advanced...Weights Beam forming Signal Processing mapped to GPU architecture Vector Processor STAP (STAP-BOY) GaN High Frequency Transistor (WBG-RF) UV Laser...Service anti- counterfeiting • Embedded security strips Technology Limitations and Barriers • Training and cost (training intensive) Land Borders North Land

Wind Measurements from a High Energy, Pulsed, 2-Micron, Coherent-Detection Doppler Lidar and Intercomparison with other sensors deployed during Field Campaign

NASA Astrophysics Data System (ADS)

Singh, Upendra; Koch, Grady; Kavaya, Michael; Yu, Jirong; Beyon, Jeffrey; Demoz, Belay

2010-05-01

This paper presents an overview of 2-micron laser transmitter development at NASA Langley Research Center (LaRC) for coherent-detection lidar profiling of winds. The novel high-energy, 2-micron, Ho:Tm:LuLiF laser technology developed at NASA Langley was employed to study laser technology currently envisioned by NASA for future global coherent Doppler lidar winds measurement. The 250 mJ, 10 Hz laser was designed as an integral part of a compact lidar transceiver developed for future aircraft flight. Ground-based wind profiles made with this transceiver will be presented. NASA Langley is currently funded to build complete Doppler lidar systems using this transceiver for the DC-8 and WB-57 aircraft. The WB-57 flights will present a more severe environment and will require autonomous operation of the lidar system. The DC-8 lidar system is a likely component of future NASA hurricane research. It will include real-time data processing and display, as well as full data archiving. The LaRC mobile lidar was deployed at Howard University facility in Beltsville, Maryland as part of NASA HQ funded (ROSES-2007, Wind Lidar Science Proposal entitled "Intercomparison of Multiple Lidars for Wind Measurements). During the campaign, testing of the lidar was combined with a field campaign to operate a 2-micron coherent lidar alongside a 355-nm direct detection lidar to demonstrate the hybrid wind lidar concept. Besides lidar, many other meteorological sensors were located at the campaign site, including wind measuring balloon sondes, sonic and propeller anemometers mounted on a tower, and a 915-MHz radio acoustic sounding system. Comparisons among these wind measurement sensors will be presented at the conference.

A Search for Laser Emission with Megawatt Thresholds from 5600 FGKM Stars

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

Tellis, Nathaniel K.; Marcy, Geoffrey W., E-mail: Nate.tellis@gmail.com

We searched high-resolution spectra of 5600 nearby stars for emission lines that are both inconsistent with a natural origin and unresolved spatially, as would be expected from extraterrestrial optical lasers. The spectra were obtained with the Keck 10 m telescope, including light coming from within 0.5 arcsec of the star, corresponding typically to within a few to tens of astronomical units of the star, and covering nearly the entire visible wavelength range from 3640 to 7890 Å. We establish detection thresholds by injecting synthetic laser emission lines into our spectra and blindly analyzing them for detections. We compute flux density detectionmore » thresholds for all wavelengths and spectral types sampled. Our detection thresholds for the power of the lasers themselves range from 3 kW to 13 MW, independent of distance to the star but dependent on the competing “glare” of the spectral energy distribution of the star and on the wavelength of the laser light, launched from a benchmark, diffraction-limited 10 m class telescope. We found no such laser emission coming from the planetary region around any of the 5600 stars. Because they contain roughly 2000 lukewarm, Earth-size planets, we rule out models of the Milky Way in which over 0.1% of warm, Earth-size planets harbor technological civilizations that, intentionally or not, are beaming optical lasers toward us. A next-generation spectroscopic laser search will be done by the Breakthrough Listen initiative, targeting more stars, especially stellar types overlooked here including spectral types O, B, A, early F, late M, and brown dwarfs, and astrophysical exotica.« less

Photonics

NASA Technical Reports Server (NTRS)

1991-01-01

Optoelectronic materials and devices are examined. Optoelectronic devices, which generate, detect, modulate, or switch electromagnetic radiation are being developed for a variety of space applications. The program includes spatial light modulators, solid state lasers, optoelectronic integrated circuits, nonlinear optical materials and devices, fiber optics, and optical networking photovoltaic technology and optical processing.

Semiconductor Laser Multi-Spectral Sensing and Imaging

PubMed Central

Le, Han Q.; Wang, Yang

2010-01-01

Multi-spectral laser imaging is a technique that can offer a combination of the laser capability of accurate spectral sensing with the desirable features of passive multispectral imaging. The technique can be used for detection, discrimination, and identification of objects by their spectral signature. This article describes and reviews the development and evaluation of semiconductor multi-spectral laser imaging systems. Although the method is certainly not specific to any laser technology, the use of semiconductor lasers is significant with respect to practicality and affordability. More relevantly, semiconductor lasers have their own characteristics; they offer excellent wavelength diversity but usually with modest power. Thus, system design and engineering issues are analyzed for approaches and trade-offs that can make the best use of semiconductor laser capabilities in multispectral imaging. A few systems were developed and the technique was tested and evaluated on a variety of natural and man-made objects. It was shown capable of high spectral resolution imaging which, unlike non-imaging point sensing, allows detecting and discriminating objects of interest even without a priori spectroscopic knowledge of the targets. Examples include material and chemical discrimination. It was also shown capable of dealing with the complexity of interpreting diffuse scattered spectral images and produced results that could otherwise be ambiguous with conventional imaging. Examples with glucose and spectral imaging of drug pills were discussed. Lastly, the technique was shown with conventional laser spectroscopy such as wavelength modulation spectroscopy to image a gas (CO). These results suggest the versatility and power of multi-spectral laser imaging, which can be practical with the use of semiconductor lasers. PMID:22315555

Semiconductor laser multi-spectral sensing and imaging.

PubMed

Le, Han Q; Wang, Yang

2010-01-01

Multi-spectral laser imaging is a technique that can offer a combination of the laser capability of accurate spectral sensing with the desirable features of passive multispectral imaging. The technique can be used for detection, discrimination, and identification of objects by their spectral signature. This article describes and reviews the development and evaluation of semiconductor multi-spectral laser imaging systems. Although the method is certainly not specific to any laser technology, the use of semiconductor lasers is significant with respect to practicality and affordability. More relevantly, semiconductor lasers have their own characteristics; they offer excellent wavelength diversity but usually with modest power. Thus, system design and engineering issues are analyzed for approaches and trade-offs that can make the best use of semiconductor laser capabilities in multispectral imaging. A few systems were developed and the technique was tested and evaluated on a variety of natural and man-made objects. It was shown capable of high spectral resolution imaging which, unlike non-imaging point sensing, allows detecting and discriminating objects of interest even without a priori spectroscopic knowledge of the targets. Examples include material and chemical discrimination. It was also shown capable of dealing with the complexity of interpreting diffuse scattered spectral images and produced results that could otherwise be ambiguous with conventional imaging. Examples with glucose and spectral imaging of drug pills were discussed. Lastly, the technique was shown with conventional laser spectroscopy such as wavelength modulation spectroscopy to image a gas (CO). These results suggest the versatility and power of multi-spectral laser imaging, which can be practical with the use of semiconductor lasers.

The Spectral Emission Characteristics of Laser Induced Plasma on Tea Samples

NASA Astrophysics Data System (ADS)

Zheng, Peichao; Shi, Minjie; Wang, Jinmei; Liu, Hongdi

2015-08-01

Laser induced breakdown spectroscopy (LIBS) provides a useful technique for food security as well as determining nutrition contents. In this paper, optical emission studies of laser induced plasma on commercial tea samples were carried out. The spectral intensities of Mg, Mn, Ca, Al, C and CN vibration bands varying with laser energy and the detection delay time of an intensified charge coupled device were studied. In addition, the relative concentrations of six microelements, i.e., Mg, Mn, Ca, Al, Na and K, were analyzed semi-quantitatively as well as H, for four kinds of tea samples. Moreover, the plasma parameters were explored, including electron temperature and electron number density. The electron temperature and electron number density were around 11000 K and 1017 cm-3, respectively. The results show that it is reasonable to consider the LIBS technique as a new method for analyzing the compositions of tea leaf samples. supported by National Natural Science Foundation of China (No. 61205149), the Scientific and Technological Talents Training Project of Chongqing, China (No. CSTC2013kjrc-qnrc40002), the Scientific and Technological Project of Nan'an District (2011) and the Visiting Scholarship of State Key Laboratory of Power Transmission Equipment & System Security and New Technology at Chongqing University, China (No. 2007DA10512714409)

Innovative mid-infrared detector concepts

NASA Astrophysics Data System (ADS)

Höfling, Sven; Pfenning, Andreas; Weih, Robert; Ratajczak, Albert; Hartmann, Fabian; Knebl, Georg; Kamp, Martin; Worschech, Lukas

2016-09-01

Gas sensing is a key technology with applications in various industrial, medical and environmental areas. Optical detection mechanisms allow for a highly selective, contactless and fast detection. For this purpose, rotational-vibrational absorption bands within the mid infrared (MIR) spectral region are exploited and probed with appropriate light sources. During the past years, the development of novel laser concepts such as interband cascade lasers (ICLs) and quantum cascade lasers (QCLs) has driven a continuous optimization of MIR laser sources. On the other hand side, there has been relatively little progress on detectors in this wavelength range. Here, we study two novel and promising GaSb-based detector concepts: Interband cascade detectors (ICD) and resonant tunneling diode (RTD) photodetectors. ICDs are a promising approach towards highly sensitive room temperature detection of MIR radiation. They make use of the cascading scheme that is enabled by the broken gap alignment of the two binaries GaSb and InAs. The interband transition in GaSb/InAs-superlattices (SL) allows for normal incidence detection. The cut-off wavelength, which determines the low energy detection limit, can be engineered via the SL period. RTD photodetectors act as low noise and high speed amplifiers of small optically generated electrical signals. In contrast to avalanche photodiodes, where the gain originates from multiplication due to impact ionization, in RTD photodetectors a large tunneling current is modulated via Coulomb interaction by the presence of photogenerated minority charge carriers. For both detector concepts, first devices operational at room temperature have been realized.

Broadband infrared imaging spectroscopy for standoff detection of trace explosives

NASA Astrophysics Data System (ADS)

Kendziora, Christopher A.; Furstenberg, Robert; Papantonakis, Michael; Nguyen, Viet; McGill, R. Andrew

2016-05-01

This manuscript describes advancements toward a mobile platform for standoff detection of trace explosives on relevant substrates using broadband infrared spectroscopic imaging. In conjunction with this, we are developing a technology for detection based on photo-thermal infrared (IR) imaging spectroscopy (PT-IRIS). PT-IRIS leverages one or more IR quantum cascade lasers (QCL), tuned to strong absorption bands in the analytes and directed to illuminate an area on a surface of interest. An IR focal plane array is used to image the surface thermal emission upon laser illumination. The PT-IRIS signal is processed as a hyperspectral image cube comprised of spatial, spectral and temporal dimensions as vectors within a detection algorithm. Here we describe methods to increase both sensitivity to trace explosives and selectivity between different analyte types by exploiting a broader spectral range than in previous configurations. Previously we demonstrated PT-IRIS at several meters of standoff distance indoors and in field tests, while operating the lasers below the infrared eye-safe intensity limit (100 mW/cm2). Sensitivity to explosive traces as small as a single 10 μm diameter particle (~1 ng) has been demonstrated.

Integration of High-Resolution Laser Displacement Sensors and 3D Printing for Structural Health Monitoring

PubMed Central

Chang, Shu-Wei; Kuo, Shih-Yu; Huang, Ting-Hsuan

2017-01-01

This paper presents a novel experimental design for complex structural health monitoring (SHM) studies achieved by integrating 3D printing technologies, high-resolution laser displacement sensors, and multiscale entropy SHM theory. A seven-story structure with a variety of composite bracing systems was constructed using a dual-material 3D printer. A wireless Bluetooth vibration speaker was used to excite the ground floor of the structure, and high-resolution laser displacement sensors (1-μm resolution) were used to monitor the displacement history on different floors. Our results showed that the multiscale entropy SHM method could detect damage on the 3D-printed structures. The results of this study demonstrate that integrating 3D printing technologies and high-resolution laser displacement sensors enables the design of cheap, fast processing, complex, small-scale civil structures for future SHM studies. The novel experimental design proposed in this study provides a suitable platform for investigating the validity and sensitivity of SHM in different composite structures and damage conditions for real life applications in the future. PMID:29271937

Integration of High-Resolution Laser Displacement Sensors and 3D Printing for Structural Health Monitoring.

PubMed

Chang, Shu-Wei; Lin, Tzu-Kang; Kuo, Shih-Yu; Huang, Ting-Hsuan

2017-12-22

This paper presents a novel experimental design for complex structural health monitoring (SHM) studies achieved by integrating 3D printing technologies, high-resolution laser displacement sensors, and multiscale entropy SHM theory. A seven-story structure with a variety of composite bracing systems was constructed using a dual-material 3D printer. A wireless Bluetooth vibration speaker was used to excite the ground floor of the structure, and high-resolution laser displacement sensors (1-μm resolution) were used to monitor the displacement history on different floors. Our results showed that the multiscale entropy SHM method could detect damage on the 3D-printed structures. The results of this study demonstrate that integrating 3D printing technologies and high-resolution laser displacement sensors enables the design of cheap, fast processing, complex, small-scale civil structures for future SHM studies. The novel experimental design proposed in this study provides a suitable platform for investigating the validity and sensitivity of SHM in different composite structures and damage conditions for real life applications in the future.

Task five report: Laser communications for data acquisition networks. [characteristics of lasers and laser systems for optical communication applications

NASA Technical Reports Server (NTRS)

1973-01-01

Laser communication technology and laser communication performance are reviewed. The subjects discussed are: (1) characteristics of laser communication systems, (2) laser technology problems, (3) means of overcoming laser technology problems, and (4) potential schedule for including laser communications into data acquisition networks. Various types of laser communication systems are described and their capabilities are defined.

Mineralogy and Astrobiology Detection Using Laser Remote Sensing Instrument

NASA Technical Reports Server (NTRS)

Abedin, M. Nurul; Bradley, Arthur T.; Sharma, Shiv K.; Misra, Anupam K.; Lucey, Paul G.; Mckay, Chistopher P.; Ismail, Syed; Sandford, Stephen P.

2015-01-01

A multispectral instrument based on Raman, laser-induced fluorescence (LIF), laser-induced breakdown spectroscopy (LIBS), and a lidar system provides high-fidelity scientific investigations, scientific input, and science operation constraints in the context of planetary field campaigns with the Jupiter Europa Robotic Lander and Mars Sample Return mission opportunities. This instrument conducts scientific investigations analogous to investigations anticipated for missions to Mars and Jupiter's icy moons. This combined multispectral instrument is capable of performing Raman and fluorescence spectroscopy out to a >100 m target distance from the rover system and provides single-wavelength atmospheric profiling over long ranges (>20 km). In this article, we will reveal integrated remote Raman, LIF, and lidar technologies for use in robotic and lander-based planetary remote sensing applications. Discussions are focused on recently developed Raman, LIF, and lidar systems in addition to emphasizing surface water ice, surface and subsurface minerals, organics, biogenic, biomarker identification, atmospheric aerosols and clouds distributions, i.e., near-field atmospheric thin layers detection for next robotic-lander based instruments to measure all the above-mentioned parameters. OCIS codes: (120.0280) Remote sensing and sensors; (130.0250) Optoelectronics; (280.3640) Lidar; (300.2530) Fluorescence, laser-induced; (300.6450) Spectroscopy, Raman; (300.6365) Spectroscopy, laser induced breakdown

Incremental yield of dysplasia detection in Barrett's esophagus using volumetric laser endomicroscopy with and without laser marking compared with a standardized random biopsy protocol.

PubMed

Alshelleh, Mohammad; Inamdar, Sumant; McKinley, Matthew; Stewart, Molly; Novak, Jeffrey S; Greenberg, Ronald E; Sultan, Keith; Devito, Bethany; Cheung, Mary; Cerulli, Maurice A; Miller, Larry S; Sejpal, Divyesh V; Vegesna, Anil K; Trindade, Arvind J

2018-02-02

Volumetric laser endomicroscopy (VLE) is a new wide-field advanced imaging technology for Barrett's esophagus (BE). No data exist on incremental yield of dysplasia detection. Our aim is to report the incremental yield of dysplasia detection in BE using VLE. This is a retrospective study from a prospectively maintained database from 2011 to 2017 comparing the dysplasia yield of 4 different surveillance strategies in an academic BE tertiary care referral center. The groups were (1) random biopsies (RB), (2) Seattle protocol random biopsies (SP), (3) VLE without laser marking (VLE), and (4) VLE with laser marking (VLEL). A total of 448 consecutive patients (79 RB, 95 SP, 168 VLE, and 106 VLEL) met the inclusion criteria. After adjusting for visible lesions, the total dysplasia yield was 5.7%, 19.6%, 24.8%, and 33.7%, respectively. When compared with just the SP group, the VLEL group had statistically higher rates of overall dysplasia yield (19.6% vs 33.7%, P = .03; odds ratio, 2.1, P = .03). Both the VLEL and VLE groups had statistically significant differences in neoplasia (high-grade dysplasia and intramucosal cancer) detection compared with the SP group (14% vs 1%, P = .001 and 11% vs 1%, P = .003). A surveillance strategy involving VLEL led to a statistically significant higher yield of dysplasia and neoplasia detection compared with a standard random biopsy protocol. These results support the use of VLEL for surveillance in BE in academic centers. Copyright © 2018 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.

Fluorescence diagnosis and photochemical treatment of diseased tissue using lasers: Part I.

PubMed

Andersson-Engels, S; Johansson, J; Svanberg, S; Svanberg, K

1989-12-15

Lasers are useful in many applications in medicine and biology. Historically, most laser use has involved heat generated in the interaction of the laser beam with the tissue. Today, however, the spectroscopic aspects of this laser use are playing a more dominant role in a number of applications. In this two-part series, Sune Svanberg and co-workers present illustrations of emerging clinical applications from cooperative work performed by the Lund Institute of Technology and the Lund University Hospital. Part I includes a survey of laser techniques for atomic and molecular analyses of samples of medical interest, spectroscopic analysis of the laser-induced plasma obtained when a high-power pulsed laser beam interacts with tissue, and the use of tumor-seeking agents in combination with laser radiation to provide new possibilities for malignant tumor detection and treatment. Part II, which will appear in the January 1, 1990, issue, describes the use of laser-induced fluorescence for tumor and plaque diagnostics. Different lasers have been used, and research efforts increasingly are being focused on excimer lasers and lasers in the IR region for the ablation of atherosclerotic plaques, cell layer by cell layer.

Nanosecond-laser induced crosstalk of CMOS image sensor

NASA Astrophysics Data System (ADS)

Zhu, Rongzhen; Wang, Yanbin; Chen, Qianrong; Zhou, Xuanfeng; Ren, Guangsen; Cui, Longfei; Li, Hua; Hao, Daoliang

2018-02-01

The CMOS Image Sensor (CIS) is photoelectricity image device which focused the photosensitive array, amplifier, A/D transfer, storage, DSP, computer interface circuit on the same silicon substrate[1]. It has low power consumption, high integration,low cost etc. With large scale integrated circuit technology progress, the noise suppression level of CIS is enhanced unceasingly, and its image quality is getting better and better. It has been in the security monitoring, biometrice, detection and imaging and even military reconnaissance and other field is widely used. CIS is easily disturbed and damaged while it is irradiated by laser. It is of great significance to study the effect of laser irradiation on optoelectronic countermeasure and device for the laser strengthening resistance is of great significance. There are some researchers have studied the laser induced disturbed and damaged of CIS. They focused on the saturation, supersaturated effects, and they observed different effects as for unsaturation, saturation, supersaturated, allsaturated and pixel flip etc. This paper research 1064nm laser interference effect in a typical before type CMOS, and observring the saturated crosstalk and half the crosstalk line. This paper extracted from cmos devices working principle and signal detection methods such as the Angle of the formation mechanism of the crosstalk line phenomenon are analyzed.

Laser Energy Monitor for Double-Pulsed 2-Micrometer IPDA Lidar Application

NASA Technical Reports Server (NTRS)

Refaat, Tamer F.; Petros, Mulugeta; Remus, Ruben; Yu, Jirong; Singh, Upendra N.

2014-01-01

Integrated path differential absorption (IPDA) lidar is a remote sensing technique for monitoring different atmospheric species. The technique relies on wavelength differentiation between strong and weak absorbing features normalized to the transmitted energy. 2-micron double-pulsed IPDA lidar is best suited for atmospheric carbon dioxide measurements. In such case, the transmitter produces two successive laser pulses separated by short interval (200 microseconds), with low repetition rate (10Hz). Conventional laser energy monitors, based on thermal detectors, are suitable for low repetition rate single pulse lasers. Due to the short pulse interval in double-pulsed lasers, thermal energy monitors underestimate the total transmitted energy. This leads to measurement biases and errors in double-pulsed IPDA technique. The design and calibration of a 2-micron double-pulse laser energy monitor is presented. The design is based on a high-speed, extended range InGaAs pin quantum detectors suitable for separating the two pulse events. Pulse integration is applied for converting the detected pulse power into energy. Results are compared to a photo-electro-magnetic (PEM) detector for impulse response verification. Calibration included comparing the three detection technologies in single-pulsed mode, then comparing the pin and PEM detectors in double-pulsed mode. Energy monitor linearity will be addressed.

Demonstration of array eddy current technology for real-time monitoring of laser powder bed fusion additive manufacturing process

NASA Astrophysics Data System (ADS)

Todorov, Evgueni; Boulware, Paul; Gaah, Kingsley

2018-03-01

Nondestructive evaluation (NDE) at various fabrication stages is required to assure quality of feedstock and solid builds. Industry efforts are shifting towards solutions that can provide real-time monitoring of additive manufacturing (AM) fabrication process layer-by-layer while the component is being built to reduce or eliminate dependence on post-process inspection. Array eddy current (AEC), electromagnetic NDE technique was developed and implemented to directly scan the component without physical contact with the powder and fused layer surfaces at elevated temperatures inside a LPBF chamber. The technique can detect discontinuities, surface irregularities, and undesirable metallurgical phase transformations in magnetic and nonmagnetic conductive materials used for laser fusion. The AEC hardware and software were integrated with the L-PBF test bed. Two layer-by-layer tests of Inconel 625 coupons with AM built discontinuities and lack of fusion were conducted inside the L-PBF chamber. The AEC technology demonstrated excellent sensitivity to seeded, natural surface, and near-surface-embedded discontinuities, while also detecting surface topography. The data was acquired and imaged in a layer-by-layer sequence demonstrating the real-time monitoring capabilities of this new technology.

Advanced technologies in the ASI MLRO towards a new generation laser ranging system

NASA Technical Reports Server (NTRS)

Varghese, Thomas; Bianco, Giuseppe

1994-01-01

Matera Laser Ranging Observatory (MLRO) is a high performance, highly automated optical and astronomical observatory currently under design and development by AlliedSignal for the Italian Space Agency (ASI). It is projected to become operational at the Centro Geodesia Spaziale in Matera, Italy, in 1997. MLRO, based on a 1.5-meter astronomical quality telescope, will perform ranging to spacecraft in earthbound orbits, lunar reflectors, and specially equipped deep space missions. The primary emphasis during design is to incorporate state-of-the-art technologies to produce an intelligent, automated, high accuracy ranging system that will mimic the characteristic features of a fifth generation laser ranging system. The telescope has multiple ports and foci to support future experiments in the areas of laser communications, lidar, astrometry, etc. The key features providing state-of-the-art ranging performance include: a diode-pumped picosecond (50 ps) laser, high speed (3-5 GHz) optoelectronic detection and signal processing, and a high accuracy (6 ps) high resolution (less than 2 ps) time measurement capability. The above combination of technologies is expected to yield millimeter laser ranging precision and accuracy on targets up to 300,000 km, surpassing the best operational instrument performance to date by a factor of five or more. Distributed processing and control using a state-of-the-art computing environment provides the framework for efficient operation, system optimization, and diagnostics. A computationally intelligent environment permits optimal planning, scheduling, tracking, and data processing. It also supports remote access, monitor, and control for joint experiments with other observatories.

Study on high power ultraviolet laser oil detection system

NASA Astrophysics Data System (ADS)

Jin, Qi; Cui, Zihao; Bi, Zongjie; Zhang, Yanchao; Tian, Zhaoshuo; Fu, Shiyou

2018-03-01

Laser Induce Fluorescence (LIF) is a widely used new telemetry technology. It obtains information about oil spill and oil film thickness by analyzing the characteristics of stimulated fluorescence and has an important application in the field of rapid analysis of water composition. A set of LIF detection system for marine oil pollution is designed in this paper, which uses 355nm high-energy pulsed laser as the excitation light source. A high-sensitivity image intensifier is used in the detector. The upper machine sends a digital signal through a serial port to achieve nanoseconds range-gated width control for image intensifier. The target fluorescence spectrum image is displayed on the image intensifier by adjusting the delay time and the width of the pulse signal. The spectral image is coupled to CCD by lens imaging to achieve spectral display and data analysis function by computer. The system is used to detect the surface of the floating oil film in the distance of 25m to obtain the fluorescence spectra of different oil products respectively. The fluorescence spectra of oil products are obvious. The experimental results show that the system can realize high-precision long-range fluorescence detection and reflect the fluorescence characteristics of the target accurately, with broad application prospects in marine oil pollution identification and oil film thickness detection.

Compact Laser Multi-gas Spectral Sensors for Spacecraft Systems

NASA Technical Reports Server (NTRS)

Tittel, Frank K.

1997-01-01

The objective of this research effort has been the development of a new gas sensor technology to meet NASA requirements for spacecraft and space station human life support systems for sensitive selective and real time detection of trace gas species in the mid-infrared spectral region.

Evaluation of "Autosense-III" laser detection technology for traffic applications on I-4

DOT National Transportation Integrated Search

2001-11-01

The major tasks of this project include procuring the two AUTOSENSE III units; selecting a site on I-4 for installation of the units, installing the units successfully on I-4, establishing a remote communication link through cellular data line to dow...

Hydrazine Detection with a Tunable Diode Laser Spectrometer

NASA Technical Reports Server (NTRS)

Houseman, John; Webster, C. R.; May, R. D.; Anderson, M. S.; Margolis, J. S.; Jackson, Julie R.; Brown, Pamela R.

1999-01-01

Several instruments have been developed to measure low concentrations of hydrazine but none completely meet the sensitivity requirements while satisfying additional criteria such as quick response, stable calibration, interference free operation, online operation, reasonable cost, etc. A brief review is presented of the current technology including the electrochemical cell, the ion mobility spectrometer, the mass spectrometer, and the gas chromatograph. A review of the advantages and disadvantages of these instruments are presented here. The review also includes commercially unavailable technology such as the electronic nose and the Tunable Diode Laser (TDL) IR Spectrometer. It was found that the TDL could meet the majority of these criteria including fast response, minimum maintenance, portability, and reasonable cost. An experiment was conducted to demonstrate the feasibility of such a system using an existing (non-portable) instrument. A lead-salt tunable diode laser, cooled to 85 degrees Kelvin was used to record direct absorption and second-derivative spectra of Hydrazine at several pressures to study the sensitivity to low levels of Hydrazine. Spectra of NH3 and CO2 were used for wavelength identification of the scanned region. With a pathlength of 80 m, detection sensitivities of about 1 ppb were achieved for hydrazine in dry nitrogen at a cell pressure of 100 mbar. For spectroscopic detection of Hydrazine, spectral regions including strong Ammonia or Carbon Dioxide lines must be avoided. Strong Hydrazine absorption features were identified at 940/cm showing minimal contribution from Ammonia interferences as suitable candidates for Hydrazine gas detection. For the studies reported here, the particular laser diode could only cover the narrow regions near 962/cm and 965/cm where strong Ammonia interferences were expected. However, the high resolution (0.001/cm) of the TDL spectrometer allowed individual lines of Hydrazine to be identified away from interferences from either Ammonia or Carbon Dioxide, especially at lower pressures. A Hydrazine line was identified at 961.75/cm which was free from Ammonia absorption and would be suitable to monitor hydrazine levels. This paper also shows data on the degradation of the detectivity of Hydrazine with increasing pressure. Several design options for a portable unit are presented, including designs with near IR and Quantum Cascade laser components which do not require liquid nitrogen cooling.

Flight phasemeter on the Laser Ranging Interferometer on the GRACE Follow-On mission

NASA Astrophysics Data System (ADS)

Bachman, B.; de Vine, G.; Dickson, J.; Dubovitsky, S.; Liu, J.; Klipstein, W.; McKenzie, K.; Spero, R.; Sutton, A.; Ware, B.; Woodruff, C.

2017-05-01

As the first inter-spacecraft laser interferometer, the Laser Ranging Interferometer (LRI) on the GRACE Follow-On Mission will demonstrate interferometry technology relevant to the LISA mission. This paper focuses on the completed LRI Laser Ranging Processor (LRP), which includes heterodyne signal phase tracking at μ {{cycle/}}\\sqrt{{{Hz}}} precision, differential wavefront sensing, offset frequency phase locking and Pound-Drever-Hall laser stabilization. The LRI design has characteristics that are similar to those for LISA: 1064 nm NPRO laser source, science bandwidth in the mHz range, MHz-range intermediate frequency and Doppler shift, detected optical power of tens of picoWatts. Laser frequency stabilization has been demonstrated at a level below 30{{Hz/}}\\sqrt{{{Hz}}}, better than the LISA requirement of 300{{Hz/}}\\sqrt{{{Hz}}}. The LRP has completed all performance testing and environmental qualification and has been delivered to the GRACE Follow-On spacecraft. The LRI is poised to test the LISA techniques of tone-assisted time delay interferometry and arm-locking. GRACE Follow-On launches in 2017.

Efficient Third Harmonic Generation for Wind Lidar Applications

NASA Technical Reports Server (NTRS)

Mordaunt, David W.; Cheung, Eric C.; Ho, James G.; Palese, Stephen P.

1998-01-01

The characterization of atmospheric winds on a global basis is a key parameter required for accurate weather prediction. The use of a space based lidar system for remote measurement of wind speed would provide detailed and highly accurate data for future weather prediction models. This paper reports the demonstration of efficient third harmonic conversion of a 1 micrometer laser to provide an ultraviolet (UV) source suitable for a wind lidar system based on atmospheric molecular scattering. Although infrared based lidars using aerosol scattering have been demonstrated to provide accurate wind measurement, a UV based system using molecular or Rayleigh scattering will provide accurate global wind measurements, even in those areas of the atmosphere where the aerosol density is too low to yield good infrared backscatter signals. The overall objective of this work is to demonstrate the maturity of the laser technology and its suitability for a near term flight aboard the space shuttle. The laser source is based on diode-pumped solid-state laser technology which has been extensively demonstrated at TRW in a variety of programs and internal development efforts. The pump laser used for the third harmonic demonstration is a breadboard system, designated the Laser for Risk Reduction Experiments (LARRE), which has been operating regularly for over 5 years. The laser technology has been further refined in an engineering model designated as the Compact Advanced Pulsed Solid-State Laser (CAPSSL), in which the laser head was packaged into an 8 x 8 x 18 inch volume with a weight of approximately 61 pounds. The CAPSSL system is a ruggedized configuration suitable for typical military applications. The LARRE and CAPSSL systems are based on Nd:YAG with an output wavelength of 1064 nm. The current work proves the viability of converting the Nd:YAG fundamental to the third harmonic wavelength at 355 nm for use in a direct detection wind lidar based on atmospheric Rayleigh scattering.

Development of a Compact, Pulsed, 2-Micron, Coherent-Detection, Doppler Wind Lidar Transceiver; and Plans for Flights on NASA's DC-8 and WB-57 Aircraft

NASA Technical Reports Server (NTRS)

Kavaya, Michael J.; Singh, Upendra N.; Koch, Grady J.; Yu, Jirong; Trieu, Bo C.; Petros, Mulugeta; Petzar, Paul J.

2009-01-01

We present results of a recently completed effort to design, fabricate, and demonstrate a compact lidar transceiver for coherent-detection lidar profiling of winds. The novel high-energy, 2-micron, Ho:Tm:LuLiF laser technology developed at NASA Langley was employed to permit study of the laser technology currently envisioned by NASA for global coherent Doppler lidar measurement of winds in the future. The 250 mJ, 10 Hz compact transceiver was also designed for future aircraft flight. Ground-based wind profiles made with this transceiver will be presented. NASA Langley is currently funded to build complete Doppler lidar systems using this transceiver for the DC-8 and WB-57 aircraft. The WB-57 flights will present a more severe environment and will require autonomous operation of the lidar system. The DC-8 lidar system is a likely component of future NASA hurricane research. It will include real-time data processing and display, as well as full data archiving. We will attempt to co-fly on both aircraft with a direct-detection Doppler wind lidar system being prepared by NASA Goddard Space Flight Center.

Modeling job sites in real time to improve safety during equipment operation

NASA Astrophysics Data System (ADS)

Caldas, Carlos H.; Haas, Carl T.; Liapi, Katherine A.; Teizer, Jochen

2006-03-01

Real-time three-dimensional (3D) modeling of work zones has received an increasing interest to perform equipment operation faster, safer and more precisely. In addition, hazardous job site environment like they exist on construction sites ask for new devices which can rapidly and actively model static and dynamic objects. Flash LADAR (Laser Detection and Ranging) cameras are one of the recent technology developments which allow rapid spatial data acquisition of scenes. Algorithms that can process and interpret the output of such enabling technologies into threedimensional models have the potential to significantly improve work processes. One particular important application is modeling the location and path of objects in the trajectory of heavy construction equipment navigation. Detecting and mapping people, materials and equipment into a three-dimensional computer model allows analyzing the location, path, and can limit or restrict access to hazardous areas. This paper presents experiments and results of a real-time three-dimensional modeling technique to detect static and moving objects within the field of view of a high-frame update rate laser range scanning device. Applications related to heavy equipment operations on transportation and construction job sites are specified.

Green fiber lasers: An alternative to traditional DPSS green lasers for flow cytometry

PubMed Central

Telford, William G.; Babin, Sergey A.; Khorev, Serge V.; Rowe, Stephen H.

2009-01-01

Green and yellow diode-pumped solid state (DPSS) lasers (532 and 561 nm) have become common fixtures on flow cytometers, due to their efficient excitation of phycoerythrin (PE) and its tandems, and their ability to excite an expanding array of expressible red fluorescent proteins. Nevertheless, they have some disadvantages. DPSS 532 nm lasers emit very close to the fluorescein bandwidth, necessitating optical modifications to permit detection of fluorescein and GFP. DPSS 561 nm lasers likewise emit very close to the PE detection bandwidth, and also cause unwanted excitation of APC and its tandems, requiring high levels of crossbeam compensation to reduce spectral overlap into the PE tandems. In this paper, we report the development of a new generation of green fiber lasers that can be engineered to emit in the range between 532 and 561 nm. A 550 nm green fiber laser was integrated into both a BD LSR II™ cuvette and FACSVantage DiVa™ jet-in-air cell sorter. This laser wavelength avoided both the fluorescein and PE bandwidths, and provided better excitation of PE and the red fluorescent proteins DsRed and dTomato than a power-matched 532 nm source. Excitation at 550 nm also caused less incidental excitation of APC and its tandems, reducing the need for crossbeam compensation. Excitation in the 550 nm range therefore proved to be a good compromise between 532 and 561 nm sources. Fiber laser technology is therefore providing the flexibility necessary for precisely matching laser wavelengths to our flow cytometry applications. PMID:19777600

Whole-field digital vibrometer system for buried landmine detection

NASA Astrophysics Data System (ADS)

Lal, Amit; Hess, Cecil; Scott, Eddie; Dang, Michael; Nichols, Robert

2005-06-01

Previous results have shown the potential of acoustic-to-seismic coupling with Laser Doppler Vibrometry for the detection of buried landmines. An important objective of the present technology is to improve the spatial resolution and the speed of the measurement. In this paper, MetroLaser reports on a whole-field digital vibrometer (WDV) that measures an entire one meter area with sub-centimeter spatial resolution in just a few seconds. The WDV is based on a dual-pulsed laser such that each pulse illuminates a one meter area on the ground, and the temporal separation between the two laser pulses can be adjusted to match the ground excitation frequency. By sweeping this excitation frequency, a displacement map of the ground at each frequency can be quickly generated. In addition, an innovative speckle repositioning strategy allows for movement of the measurement platform at reasonable speeds while still obtaining measurements with interferometric precision. This paper describes the WDV instrument and presents preliminary experimental results obtained with this system. This research is being supported by the U.S. Army RDECOM CERDEC NVESD under Contract W909MY04-C-0004.

A simulator for airborne laser swath mapping via photon counting

NASA Astrophysics Data System (ADS)

Slatton, K. C.; Carter, W. E.; Shrestha, R.

2005-06-01

Commercially marketed airborne laser swath mapping (ALSM) instruments currently use laser rangers with sufficient energy per pulse to work with return signals of thousands of photons per shot. The resulting high signal to noise level virtually eliminates spurious range values caused by noise, such as background solar radiation and sensor thermal noise. However, the high signal level approach requires laser repetition rates of hundreds of thousands of pulses per second to obtain contiguous coverage of the terrain at sub-meter spatial resolution, and with currently available technology, affords little scalability for significantly downsizing the hardware, or reducing the costs. A photon-counting ALSM sensor has been designed by the University of Florida and Sigma Space, Inc. for improved topographic mapping with lower power requirements and weight than traditional ALSM sensors. Major elements of the sensor design are presented along with preliminary simulation results. The simulator is being developed so that data phenomenology and target detection potential can be investigated before the system is completed. Early simulations suggest that precise estimates of terrain elevation and target detection will be possible with the sensor design.

[Research status and prospects of DNA test on difficult specimens].

PubMed

Dang, Hua-Wei; Mao, Jiong; Wang, Hui; Huang, Jiang-Ping; Bai, Xiao-Gang

2012-02-01

This paper reviews the advances of DNA detection on three types of difficult biological specimens including degraded samples, trace evidences and mixed samples. The source of different samples, processing methods and announcements were analyzed. New methods such as mitochondrial test system, changing the original experimental conditions, low-volume PCR amplification and new technologies such as whole genome amplification techniques, laser capture micro-dissection, and mini-STR technology in recent years are introduced.

Defect Detection on Carbon Fibre Reinforced Plastics (cfrp) with Laser Generated Lamb Waves

NASA Astrophysics Data System (ADS)

Focke, O.; Huke, P.; Hildebrandt, A.

2011-06-01

Standard ultrasound methods using a phased-array or a single transducer are commonly used for non-destructive evaluation (NDE) during manufacturing of carbon fiber reinforced plastics (CFRP) parts and certificated testing schemes were developed for individual parts and geometries. However, most testing methods need direct contact, matching gels and remain therefore time consuming. Laser-Ultrasonics is advantageous due to the contactless measurement technology and high accessibility even on complex parts. Despite the non-destructive testing with body waves, we show that the NDE can be expanded using two-dimensional surface (Lamb) waves for detection of delaminations close to the surface or small deteriorations caused by e.g. impacts. Lamb waves have been excited with a single transducer and with a short-pulse Laser with additionally producing A0-and S0-Lamb waves. The waves were detected with a shearography setup that allows for measuring two-dimensionally the displacement of a surface. Short integration times of the camera were realized using a pulsed ruby laser for illumination. As a consequence to the anisotropy the propagation in different directions exhibits individual characteristics like amplitude, damping and velocity. This has motivated to build up models for the propagation of Lamb waves and to compare them with experimental results.

Roadmap on optical sensors.

PubMed

Ferreira, Mário F S; Castro-Camus, Enrique; Ottaway, David J; López-Higuera, José Miguel; Feng, Xian; Jin, Wei; Jeong, Yoonchan; Picqué, Nathalie; Tong, Limin; Reinhard, Björn M; Pellegrino, Paul M; Méndez, Alexis; Diem, Max; Vollmer, Frank; Quan, Qimin

2017-08-01

Sensors are devices or systems able to detect, measure and convert magnitudes from any domain to an electrical one. Using light as a probe for optical sensing is one of the most efficient approaches for this purpose. The history of optical sensing using some methods based on absorbance, emissive and florescence properties date back to the 16th century. The field of optical sensors evolved during the following centuries, but it did not achieve maturity until the demonstration of the first laser in 1960. The unique properties of laser light become particularly important in the case of laser-based sensors, whose operation is entirely based upon the direct detection of laser light itself, without relying on any additional mediating device. However, compared with freely propagating light beams, artificially engineered optical fields are in increasing demand for probing samples with very small sizes and/or weak light-matter interaction. Optical fiber sensors constitute a subarea of optical sensors in which fiber technologies are employed. Different types of specialty and photonic crystal fibers provide improved performance and novel sensing concepts. Actually, structurization with wavelength or subwavelength feature size appears as the most efficient way to enhance sensor sensitivity and its detection limit. This leads to the area of micro- and nano-engineered optical sensors. It is expected that the combination of better fabrication techniques and new physical effects may open new and fascinating opportunities in this area. This roadmap on optical sensors addresses different technologies and application areas of the field. Fourteen contributions authored by experts from both industry and academia provide insights into the current state-of-the-art and the challenges faced by researchers currently. Two sections of this paper provide an overview of laser-based and frequency comb-based sensors. Three sections address the area of optical fiber sensors, encompassing both conventional, specialty and photonic crystal fibers. Several other sections are dedicated to micro- and nano-engineered sensors, including whispering-gallery mode and plasmonic sensors. The uses of optical sensors in chemical, biological and biomedical areas are described in other sections. Different approaches required to satisfy applications at visible, infrared and THz spectral regions are also discussed. Advances in science and technology required to meet challenges faced in each of these areas are addressed, together with suggestions on how the field could evolve in the near future.

[The research on separating and extracting overlapping spectral feature lines in LIBS using damped least squares method].

PubMed

Wang, Yin; Zhao, Nan-jing; Liu, Wen-qing; Yu, Yang; Fang, Li; Meng, De-shuo; Hu, Li; Zhang, Da-hai; Ma, Min-jun; Xiao, Xue; Wang, Yu; Liu, Jian-guo

2015-02-01

In recent years, the technology of laser induced breakdown spectroscopy has been developed rapidly. As one kind of new material composition detection technology, laser induced breakdown spectroscopy can simultaneously detect multi elements fast and simply without any complex sample preparation and realize field, in-situ material composition detection of the sample to be tested. This kind of technology is very promising in many fields. It is very important to separate, fit and extract spectral feature lines in laser induced breakdown spectroscopy, which is the cornerstone of spectral feature recognition and subsequent elements concentrations inversion research. In order to realize effective separation, fitting and extraction of spectral feature lines in laser induced breakdown spectroscopy, the original parameters for spectral lines fitting before iteration were analyzed and determined. The spectral feature line of' chromium (Cr I : 427.480 nm) in fly ash gathered from a coal-fired power station, which was overlapped with another line(FeI: 427.176 nm), was separated from the other one and extracted by using damped least squares method. Based on Gauss-Newton iteration, damped least squares method adds damping factor to step and adjust step length dynamically according to the feedback information after each iteration, in order to prevent the iteration from diverging and make sure that the iteration could converge fast. Damped least squares method helps to obtain better results of separating, fitting and extracting spectral feature lines and give more accurate intensity values of these spectral feature lines: The spectral feature lines of chromium in samples which contain different concentrations of chromium were separated and extracted. And then, the intensity values of corresponding spectral lines were given by using damped least squares method and least squares method separately. The calibration curves were plotted, which showed the relationship between spectral line intensity values and chromium concentrations in different samples. And then their respective linear correlations were compared. The experimental results showed that the linear correlation of the intensity values of spectral feature lines and the concentrations of chromium in different samples, which was obtained by damped least squares method, was better than that one obtained by least squares method. And therefore, damped least squares method was stable, reliable and suitable for separating, fitting and extracting spectral feature lines in laser induced breakdown spectroscopy.

Roadmap on optical sensors

NASA Astrophysics Data System (ADS)

Ferreira, Mário F. S.; Castro-Camus, Enrique; Ottaway, David J.; López-Higuera, José Miguel; Feng, Xian; Jin, Wei; Jeong, Yoonchan; Picqué, Nathalie; Tong, Limin; Reinhard, Björn M.; Pellegrino, Paul M.; Méndez, Alexis; Diem, Max; Vollmer, Frank; Quan, Qimin

2017-08-01

Sensors are devices or systems able to detect, measure and convert magnitudes from any domain to an electrical one. Using light as a probe for optical sensing is one of the most efficient approaches for this purpose. The history of optical sensing using some methods based on absorbance, emissive and florescence properties date back to the 16th century. The field of optical sensors evolved during the following centuries, but it did not achieve maturity until the demonstration of the first laser in 1960. The unique properties of laser light become particularly important in the case of laser-based sensors, whose operation is entirely based upon the direct detection of laser light itself, without relying on any additional mediating device. However, compared with freely propagating light beams, artificially engineered optical fields are in increasing demand for probing samples with very small sizes and/or weak light-matter interaction. Optical fiber sensors constitute a subarea of optical sensors in which fiber technologies are employed. Different types of specialty and photonic crystal fibers provide improved performance and novel sensing concepts. Actually, structurization with wavelength or subwavelength feature size appears as the most efficient way to enhance sensor sensitivity and its detection limit. This leads to the area of micro- and nano-engineered optical sensors. It is expected that the combination of better fabrication techniques and new physical effects may open new and fascinating opportunities in this area. This roadmap on optical sensors addresses different technologies and application areas of the field. Fourteen contributions authored by experts from both industry and academia provide insights into the current state-of-the-art and the challenges faced by researchers currently. Two sections of this paper provide an overview of laser-based and frequency comb-based sensors. Three sections address the area of optical fiber sensors, encompassing both conventional, specialty and photonic crystal fibers. Several other sections are dedicated to micro- and nano-engineered sensors, including whispering-gallery mode and plasmonic sensors. The uses of optical sensors in chemical, biological and biomedical areas are described in other sections. Different approaches required to satisfy applications at visible, infrared and THz spectral regions are also discussed. Advances in science and technology required to meet challenges faced in each of these areas are addressed, together with suggestions on how the field could evolve in the near future.

The investigation on mirrors maladjustment for RLG

NASA Astrophysics Data System (ADS)

He, Xiao-qing; Gao, Ai-hua; Hu, Shang-bin; Lu, Zhi-guo

2011-06-01

In order to meet the high demand of the entire technology processing, the error compensation method is usually used to correct them and is premised on a good understanding of error sources and the law of the errors. In this paper, based on the theories of Collins's Integral and Collins's EIKONAL Function and the MATLAB software, we simulated and calculated the spatial distribution of optical beam in the cavity of the ring laser gyro under the resonator's maladjustment caused by the technology processing. From the simulation results, we can get that to the small-gain lasers, the same amount of disorders in the different structures have different effects on the spatial distribution of the beam, and the structures using the spherical mirrors relatively have the small impact on the beam; under the same disorder in the same cavity shape, the signal light and the calibration light which are respectively detected from the mirror M1 and M4 are different; under the same structures, different mirrors with the same amount of disorder will cause the different beat frequency difference; because of the disorders, the spot centers of clockwise and counterclockwise waves happen shift and will seriously affect the normal operation of the laser gyro if the imbalance reaches a certain degree. This work has a guiding role in the mirror adjustment of the laser gyros' technology processing, and has a reference value to the survival rate of the laser gyros and the improvement of measurement accuracy.

Optical communications and a comparison of optical technologies for a high data rate return link from Mars

NASA Technical Reports Server (NTRS)

Spence, Rodney L.

1993-01-01

The important principles of direct- and heterodyne-detection optical free-space communications are reviewed. Signal-to-noise-ratio (SNR) and bit-error-rate (BER) expressions are derived for both the direct-detection and heterodyne-detection optical receivers. For the heterodyne system, performance degradation resulting from received-signal and local oscillator-beam misalignment and laser phase noise is analyzed. Determination of interfering background power from local and extended background sources is discussed. The BER performance of direct- and heterodyne-detection optical links in the presence of Rayleigh-distributed random pointing and tracking errors is described. Finally, several optical systems employing Nd:YAG, GaAs, and CO2 laser sources are evaluated and compared to assess their feasibility in providing high-data-rate (10- to 1000-Mbps) Mars-to-Earth communications. It is shown that the root mean square (rms) pointing and tracking accuracy is a critical factor in defining the system transmitting laser-power requirements and telescope size and that, for a given rms error, there is an optimum telescope aperture size that minimizes the required power. The results of the analysis conducted indicate that, barring the achievement of extremely small rms pointing and tracking errors (less than 0.2 microrad), the two most promising types of optical systems are those that use an Nd:YAG laser (lambda = 1.064 microns) and high-order pulse position modulator (PPM) and direct detection, and those that use a CO2 laser (lambda = 10.6 microns) and phase shifting keying homodyne modulation and coherent detection. For example, for a PPM order of M = 64 and an rms pointing accuracy of 0.4 microrad, an Nd:YAG system can be used to implement a 100-Mbps Mars link with a 40-cm transmitting telescope, a 20-W laser, and a 10-m receiving photon bucket. Under the same conditions, a CO2 system would require 3-m transmitting and receiving telescopes and a 32-W laser to implement such a link. Other types of optical systems, such as a semiconductor laser systems, are impractical in the presence of large rms pointing errors because of the high power requirements of the 100-Mbps Mars link, even when optimal-size telescopes are used.

ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT LASER TOUCH AND TECHNOLOGIES, LLC LASER TOUCH MODEL LT-B512

EPA Science Inventory

The Environmental Technology Verification report discusses the technology and performance of Laser Touch model LT-B512 targeting device manufactured by Laser Touch and Technologies, LLC, for manual spray painting operations. The relative transfer efficiency (TE) improved an avera...

Airborne laser sensors and integrated systems

NASA Astrophysics Data System (ADS)

Sabatini, Roberto; Richardson, Mark A.; Gardi, Alessandro; Ramasamy, Subramanian

2015-11-01

The underlying principles and technologies enabling the design and operation of airborne laser sensors are introduced and a detailed review of state-of-the-art avionic systems for civil and military applications is presented. Airborne lasers including Light Detection and Ranging (LIDAR), Laser Range Finders (LRF), and Laser Weapon Systems (LWS) are extensively used today and new promising technologies are being explored. Most laser systems are active devices that operate in a manner very similar to microwave radars but at much higher frequencies (e.g., LIDAR and LRF). Other devices (e.g., laser target designators and beam-riders) are used to precisely direct Laser Guided Weapons (LGW) against ground targets. The integration of both functions is often encountered in modern military avionics navigation-attack systems. The beneficial effects of airborne lasers including the use of smaller components and remarkable angular resolution have resulted in a host of manned and unmanned aircraft applications. On the other hand, laser sensors performance are much more sensitive to the vagaries of the atmosphere and are thus generally restricted to shorter ranges than microwave systems. Hence it is of paramount importance to analyse the performance of laser sensors and systems in various weather and environmental conditions. Additionally, it is important to define airborne laser safety criteria, since several systems currently in service operate in the near infrared with considerable risk for the naked human eye. Therefore, appropriate methods for predicting and evaluating the performance of infrared laser sensors/systems are presented, taking into account laser safety issues. For aircraft experimental activities with laser systems, it is essential to define test requirements taking into account the specific conditions for operational employment of the systems in the intended scenarios and to verify the performance in realistic environments at the test ranges. To support the development of such requirements, useful guidelines are provided for test and evaluation of airborne laser systems including laboratory, ground and flight test activities.

Detection prospects for the Cosmic Neutrino Background using laser interferometers

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

Domcke, Valerie; Spinrath, Martin, E-mail: valerie.domcke@apc.univ-paris7.fr, E-mail: martin.spinrath@cts.nthu.edu.tw

The cosmic neutrino background is a key prediction of Big Bang cosmology which has not been observed yet. The movement of the earth through this neutrino bath creates a force on a pendulum, as if it were exposed to a cosmic wind. We revise here estimates for the resulting pendulum acceleration and compare it to the theoretical sensitivity of an experimental setup where the pendulum position is measured using current laser interferometer technology as employed in gravitational wave detectors. We discuss how a significant improvement of this setup can be envisaged in a micro gravity environment. The proposed setup couldmore » also function as a dark matter detector in the sub-MeV range, which currently eludes direct detection constraints.« less

Detection prospects for the Cosmic Neutrino Background using laser interferometers

NASA Astrophysics Data System (ADS)

Domcke, Valerie; Spinrath, Martin

2017-06-01

The cosmic neutrino background is a key prediction of Big Bang cosmology which has not been observed yet. The movement of the earth through this neutrino bath creates a force on a pendulum, as if it were exposed to a cosmic wind. We revise here estimates for the resulting pendulum acceleration and compare it to the theoretical sensitivity of an experimental setup where the pendulum position is measured using current laser interferometer technology as employed in gravitational wave detectors. We discuss how a significant improvement of this setup can be envisaged in a micro gravity environment. The proposed setup could also function as a dark matter detector in the sub-MeV range, which currently eludes direct detection constraints.

Ultra-Sensitive Photoreceiver Boosts Data Transmission

NASA Technical Reports Server (NTRS)

2007-01-01

NASA depends on advanced, ultra-sensitive photoreceivers and photodetectors to provide high-data communications and pinpoint image-detection and -recognition capabilities from great distances. In 2003, Epitaxial Technologies LLC was awarded a Small Business Innovation Research (SBIR) contract from Goddard Space Flight Center to address needs for advanced sensor components. Epitaxial developed a photoreciever capable of single proton sensitivity that is also smaller, lighter, and requires less power than its predecessor. This receiver operates in several wavelength ranges; will allow data rate transmissions in the terabit range; and will enhance Earth-based missions for remote sensing of crops and other natural resources, including applications for fluorescence and phosphorescence detection. Widespread military and civilian applications are anticipated, especially through enhancing fiber optic communications, laser imaging, and laser communications.

Quantum cascade laser-based screening portal for the detection of explosive precursors

NASA Astrophysics Data System (ADS)

Lindley, Ruth; Normand, Erwan; Howieson, Iain; McCulloch, Michael; Black, Paul; Lewis, Colin; Foulger, Brian

2007-10-01

In recent years, quantum cascade lasers (QCL) have been proven in robust, high-performance gas analyzers designed for continuous emission monitoring (CEM) in harsh environments. In 2006, Cascade Technologies reported progress towards adapting its patented technology for homeland security applications by publishing initial results on explosive compound detection. This paper presents the performance and results from a QCL-based people screening portal developed during the past year and aimed at the detection of precursors used in the make up of improvised explosive devices (IED). System tests have been carried out on a large number of potential interferents, together with target precursor materials, reinforcing original assumptions that compound fingerprinting can be effectively demonstrated using this technique. Results have shown that an extremely high degree of specificity can be achieved with a sub-second response time. Furthermore, it has been shown that unambiguous precursor signature recognition can be extended to compound mixtures associated with the intermediate stages in the make up of IEDs, whilst maintaining interferent immunity. The portal sensitivity was configured for parts per billion (ppb) detection level thresholds, but is currently being reconfigured for sub-ppb detection. In summary, the results obtained from the QCL based portal indicate that development of a low cost detection system, with enhanced features such as low false positive and high throughput screening of individuals or items, is possible. Development and testing was carried out with the support of the UK government.

Improved photoacoustic dosimetry for retinal laser surgery

NASA Astrophysics Data System (ADS)

Dufour, Suzie; Brown, Robert B.; Gallant, Pascal; Mermut, Ozzy

2018-02-01

Lasers are employed for numerous medical interventions by exploiting ablative, disruptive or thermal effects. In ocular procedures, lasers have been used for decades to treat diseases such as diabetic retinopathy, macular edema and aged related macular degeneration via photocoagulation of retinal tissues. Although laser photocoagulation is well established in today's practice, efforts to improve clinical outcomes by reducing the collateral damage from thermal diffusion is leading to novel treatments using shorter (μs) laser pulses (e.g. selective retinal therapy) which result in physical rather than thermal damage. However, for these new techniques to be widely utilized, a method is required to ensure safe but sufficient dosage has been applied, since no visible effects can be seen by ophthalmoscopy directly post treatment. Photoacoustic feedback presents an attractive solution, as the signal is dependent directly on absorbed dosage. Here, we present a method that takes advantage of temporal pulse formatting technology to minimize variation in absorbed dose in ophthalmic laser treatment and provide intelligent dosimetry feedback based on photoacoustic (PA) response. This method tailors the pulse to match the frequency response of the sample and/or detection chain. Depending on the system, this may include the absorbing particle size, the laser beam diameter, the laser pulse duration, tissue acoustic properties and the acoustic detector frequency response. A significant improvement (<7x) of photoacoustic signal-to-noise ratio over equivalent traditional pulse formats have been achieved, while spectral analysis of the detected signal provides indications of cavitation events and other sample properties.

DETECTION AND IDENTIFICATION OF TOXIC AIR POLLUTANTS USING FIELD PORTABLE AND AIRBORNE REMOTE IMAGING SYSTEMS

EPA Science Inventory

Remote sensing technologies are a class of instrument and sensor systems that include laser imageries, imaging spectrometers, and visible to thermal infrared cameras. These systems have been successfully used for gas phase chemical compound identification in a variety of field e...

Windshear detection and avoidance - Airborne systems perspective

NASA Technical Reports Server (NTRS)

Bowles, Roland L.; Targ, Russell

1988-01-01

The generalized windshear hazard index presently defined is derived from aircraft-position wind data and remotely sensed data obtained along the extended flight path by such candidate sensor technologies as microwave Doppler radar, Doppler lidar, and IR radiometry. Attention is given here to the results of a comparative evaluation of CO2 and Ho:YAG lidar sensor-employing windshear-detection systems, over a range 1-3 km ahead of the aircraft (corresponding to 15-45 sec of warning time). While the technology for a 10.6-micron CO2 lidar system is available, an optimum 2-micron REE laser crystal-based system remains to be developed.

The Role of Adjunct Imaging in Endoscopic Detection of Dysplasia in Barrett's Esophagus.

PubMed

Kandel, Pujan; Wallace, Michael B

2017-07-01

Advances in imaging technologies have demonstrated promise in early detection of dysplasia and cancer in Barrett's esophagus (BE). Optical chromoendoscopy, dye-based chromoendoscopy, and novel technologies have provided the opportunity to visualize the cellular and subcellular structures. Only narrow-band imaging and acetic acid chromoendoscopy have reached benchmarks for clinical use. Volumetric laser endomicroscopy and molecular imaging are not established for routine use. Best practice in management of BE should be focused on careful endoscopic examination, resection, or ablation of the entire abnormal lesion, as well as the use of available imaging technique that has good diagnostic accuracy. Copyright © 2017 Elsevier Inc. All rights reserved.

Recent advances in the use of laser-induced breakdown spectroscopy (LIBS) as a rapid point-of-care pathogen diagnostic

NASA Astrophysics Data System (ADS)

Rehse, Steven; Trojand, Daniel; Putnam, Russell; Gillies, Derek; Woodman, Ryan; Sheikh, Khadija; Daabous, Andrew

2013-05-01

There is a well-known and urgent need in the fields of medicine, environmental health and safety, food-processing, and defense/security to develop new 21st Century technologies for the rapid and sensitive identification of bacterial pathogens. In only the last five years, the use of a real-time elemental (atomic) analysis performed with laser-induced breakdown spectroscopy (LIBS) has made tremendous progress in becoming a viable technology for rapid bacterial pathogen detection and identification. In this talk we will show how this laser-based optical emission spectroscopic technique is able to sensitively assay the elemental composition of bacterial cells in situ. We will also present the latest achievements of our lab to fully develop LIBS-based bacterial sensing including simulation of a rapid urinary tract infection diagnosis and investigation of a variety of autonomous multivariate analysis algorithms. Lastly, we will show how this technology is now ready to be transitioned from the laboratory to field-portable and potentially man-portable instrumentation. The introduction of such a technology into popular use could very well transform the field of bacterial biosensing - a market valued at approximately 10 billion/year world-wide. Funding for this project was provided in part by a Natural Sciences and Engineering Research Council of Canada Discovery Grant.

Feasibility of real-time geochemical analysis using LIBS (Laser-Induced Breakdown Spectroscopy) in oil wells

NASA Astrophysics Data System (ADS)

Shahin, Mohamed

2014-05-01

The oil and gas industry has attempted for many years to find new ways to analyze and determine the type of rocks drilled on a real time basis. Mud analysis logging is a direct method of detecting oil and gas in formations drilled, it depends on the "feel" of the bit to decide formation type, as well as, geochemical analysis which was introduced 30 years ago, starting with a pulsed-neutron generator (PNG) based wireline tool upon which LWD technology was based. In this paper, we are studying the feasibility of introducing a new technology for real-time geochemical analysis. Laser-induced breakdown spectroscopy (LIBS) is a type of atomic emission spectroscopy, It is a cutting-edge technology that is used for many applications such as determination of alloy composition, origin of manufacture (by monitoring trace components), and molecular analysis (unknown identification). LIBS can analyze any material regardless of its state (solid, liquid or gas), based upon that fact, we can analyze rocks, formation fluids' types and contacts between them. In cooperation with the National Institute of Laser Enhanced Science, Cairo University in Egypt, we've done tests on sandstone, limestone and coal samples acquired from different places using Nd: YAG Laser with in addition to other components that are explained in details through this paper to understand the ability of Laser to analyze rock samples and provide their elemental composition using LIBS technique. We've got promising results from the sample analysis via LIBS and discussed the possibility of deploying this technology in oilfields suggesting many applications and giving a base for achieving a quantitative elemental analysis method in view of its shortcomings and solutions.

ManPortable and UGV LIVAR: advances in sensor suite integration bring improvements to target observation and identification for the electronic battlefield

NASA Astrophysics Data System (ADS)

Lynam, Jeff R.

2001-09-01

A more highly integrated, electro-optical sensor suite using Laser Illuminated Viewing and Ranging (LIVAR) techniques is being developed under the Army Advanced Concept Technology- II (ACT-II) program for enhanced manportable target surveillance and identification. The ManPortable LIVAR system currently in development employs a wide-array of sensor technologies that provides the foot-bound soldier and UGV significant advantages and capabilities in lightweight, fieldable, target location, ranging and imaging systems. The unit incorporates a wide field-of-view, 5DEG x 3DEG, uncooled LWIR passive sensor for primary target location. Laser range finding and active illumination is done with a triggered, flash-lamp pumped, eyesafe micro-laser operating in the 1.5 micron region, and is used in conjunction with a range-gated, electron-bombarded CCD digital camera to then image the target objective in a more- narrow, 0.3$DEG, field-of-view. Target range determination is acquired using the integrated LRF and a target position is calculated using data from other onboard devices providing GPS coordinates, tilt, bank and corrected magnetic azimuth. Range gate timing and coordinated receiver optics focus control allow for target imaging operations to be optimized. The onboard control electronics provide power efficient, system operations for extended field use periods from the internal, rechargeable battery packs. Image data storage, transmission, and processing performance capabilities are also being incorporated to provide the best all-around support, for the electronic battlefield, in this type of system. The paper will describe flash laser illumination technology, EBCCD camera technology with flash laser detection system, and image resolution improvement through frame averaging.

Single-shot measurement of >1010 pulse contrast for ultra-high peak-power lasers

NASA Astrophysics Data System (ADS)

Wang, Yongzhi; Ma, Jingui; Wang, Jing; Yuan, Peng; Xie, Guoqiang; Ge, Xulei; Liu, Feng; Yuan, Xiaohui; Zhu, Heyuan; Qian, Liejia

2014-01-01

Real-time pulse-contrast observation with a high dynamic range is a prerequisite to tackle the contrast challenge in ultra-high peak-power lasers. However, the commonly used delay-scanning cross-correlator (DSCC) can only provide the time-consumed measurements for repetitive lasers. Single-shot cross-correlator (SSCC) becomes essential in optimizing laser systems and exploring contrast mechanisms. Here we report our progress in developing SSCC towards its practical use. By integrating both the techniques of scattering-noise reduction and sensitive parallel detection into SSCC, we demonstrate a high dynamic range of >1010, which, to our best knowledge, is the first demonstration of an SSCC with a dynamic range comparable to that of commercial DSCCs. The comparison of high-dynamic measurement performances between SSCC and a standard DSCC (Sequoia, Amplitude Technologies) is also carried out on a 200 TW Ti:sapphire laser, and the consistency of results verifies the veracity of our SSCC.

Results from the Galileo Laser Uplink: A JPL Demonstration of Deep-Space Optical Communications

NASA Technical Reports Server (NTRS)

Wilson, K. E.; Lesh, J. R.

1993-01-01

The successful completion of the Galileo Optical Experiment (GOPEX), represented the accomplishment of a significant milestone in JPL's optical communication plan. The experiment demonstrated the first transmission of a narrow laser beam to a deep-space vehicle. Laser pulses were beamed to the Galileo spacecraft by Earth-based transmitters at the Table Mountain Facility (TMF), California, and Starfire Optical Range (SOR), New Mexico. The experiment took place over an eight-day period (December 9 through December 16, 1992) as Galileo receded from Earth on its way to Jupiter, and covered ranges from 1 to 6 million kilometers (15 times the Earth-Moon distance), the laser uplink from TMF covered the longest known range for laser beam transmission and detection. This demonstration is the latest in a series of accomplishments by JPL in the development of deep-space optical communications technology.

Laser system for natural gas detection. Phase 1: Laboratory feasibility studies

NASA Technical Reports Server (NTRS)

Grant, W. B.; Hinkley, E. D., Jr.

1982-01-01

This project demonstrated the feasibility of using laser remote sensing technology as a tool for leak survey work in natural gas distribution systems. A laboratory device was assembled using a pair of helium neon (HeNe) lasers to measure methane. One HeNe laser emits radiation at a wavelength of 3.3922 micrometers, which corresponds to a strong absorption feature of methane, while the other emits radiation at a wavelength of 3.3911 micrometers, which corresponds to a weak absorption by methane. As a particular area is scanned for leaks, the laser is pointed at convenient topographic targets within its operating range, about 25 m. A portion of the backscattered radiation is collected by a receiver and focused onto an indium antimonide (InSb) photodetector, cooled to 77K. Methane concentrations were determined from the differential absorption at the two wavelengths for the backscattered radiation.

Advanced Ultrafast Spectroscopy for Chemical Detection of Nuclear Fuel Cycle Materials

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

Villa-Aleman, E.; Houk, A.; Spencer, W.

The development of new signatures and observables from processes related to proliferation activities are often related to the development of technologies. In our physical world, the intensity of observables is linearly related to the input drivers (light, current, voltage, etc.). Ultrafast lasers with high peak energies, opens the door to a new regime where the intensity of the observables is not necessarily linear with the laser energy. Potential nonlinear spectroscopic applications include chemical detection via remote sensing through filament generation, material characterization and processing, chemical reaction specificity, surface phenomena modifications, X-ray production, nuclear fusion, etc. The National Security Directorate lasermore » laboratory is currently working to develop new tools for nonproliferation research with femtosecond and picosecond lasers. Prior to this project, we could only achieve laser energies in the 5 nano-Joule range, preventing the study of nonlinear phenomena. To advance our nonproliferation research into the nonlinear regime we require laser pulses in the milli-Joule (mJ) energy range. We have procured and installed a 35 fs-7 mJ laser, operating at one-kilohertz repetition rate, to investigate elemental and molecular detection of materials in the laboratory with potential applications in remote sensing. Advanced, nonlinear Raman techniques will be used to study materials of interest that are in a matrix of many materials and currently with these nonlinear techniques we can achieve greater than three orders of magnitude signal enhancement. This work studying nuclear fuel cycle materials with nonlinear spectroscopies will advance SRNL research capabilities and grow a core capability within the DOE complex.« less

Improving the Sensitivity and Functionality of Mobile Webcam-Based Fluorescence Detectors for Point-of-Care Diagnostics in Global Health.

PubMed

Rasooly, Reuven; Bruck, Hugh Alan; Balsam, Joshua; Prickril, Ben; Ossandon, Miguel; Rasooly, Avraham

2016-05-17

Resource-poor countries and regions require effective, low-cost diagnostic devices for accurate identification and diagnosis of health conditions. Optical detection technologies used for many types of biological and clinical analysis can play a significant role in addressing this need, but must be sufficiently affordable and portable for use in global health settings. Most current clinical optical imaging technologies are accurate and sensitive, but also expensive and difficult to adapt for use in these settings. These challenges can be mitigated by taking advantage of affordable consumer electronics mobile devices such as webcams, mobile phones, charge-coupled device (CCD) cameras, lasers, and LEDs. Low-cost, portable multi-wavelength fluorescence plate readers have been developed for many applications including detection of microbial toxins such as C. Botulinum A neurotoxin, Shiga toxin, and S. aureus enterotoxin B (SEB), and flow cytometry has been used to detect very low cell concentrations. However, the relatively low sensitivities of these devices limit their clinical utility. We have developed several approaches to improve their sensitivity presented here for webcam based fluorescence detectors, including (1) image stacking to improve signal-to-noise ratios; (2) lasers to enable fluorescence excitation for flow cytometry; and (3) streak imaging to capture the trajectory of a single cell, enabling imaging sensors with high noise levels to detect rare cell events. These approaches can also help to overcome some of the limitations of other low-cost optical detection technologies such as CCD or phone-based detectors (like high noise levels or low sensitivities), and provide for their use in low-cost medical diagnostics in resource-poor settings.

Improving the Sensitivity and Functionality of Mobile Webcam-Based Fluorescence Detectors for Point-of-Care Diagnostics in Global Health

PubMed Central

Rasooly, Reuven; Bruck, Hugh Alan; Balsam, Joshua; Prickril, Ben; Ossandon, Miguel; Rasooly, Avraham

2016-01-01

Resource-poor countries and regions require effective, low-cost diagnostic devices for accurate identification and diagnosis of health conditions. Optical detection technologies used for many types of biological and clinical analysis can play a significant role in addressing this need, but must be sufficiently affordable and portable for use in global health settings. Most current clinical optical imaging technologies are accurate and sensitive, but also expensive and difficult to adapt for use in these settings. These challenges can be mitigated by taking advantage of affordable consumer electronics mobile devices such as webcams, mobile phones, charge-coupled device (CCD) cameras, lasers, and LEDs. Low-cost, portable multi-wavelength fluorescence plate readers have been developed for many applications including detection of microbial toxins such as C. Botulinum A neurotoxin, Shiga toxin, and S. aureus enterotoxin B (SEB), and flow cytometry has been used to detect very low cell concentrations. However, the relatively low sensitivities of these devices limit their clinical utility. We have developed several approaches to improve their sensitivity presented here for webcam based fluorescence detectors, including (1) image stacking to improve signal-to-noise ratios; (2) lasers to enable fluorescence excitation for flow cytometry; and (3) streak imaging to capture the trajectory of a single cell, enabling imaging sensors with high noise levels to detect rare cell events. These approaches can also help to overcome some of the limitations of other low-cost optical detection technologies such as CCD or phone-based detectors (like high noise levels or low sensitivities), and provide for their use in low-cost medical diagnostics in resource-poor settings. PMID:27196933

Erbium Laser Technology vs Traditional Drilling for Caries Removal: A Systematic Review with Meta-Analysis.

PubMed

Tao, Siying; Li, Lan; Yuan, He; Tao, Sibei; Cheng, Yiming; He, Libang; Li, Jiyao

2017-12-01

The study aimed to assess the efficacy of erbium laser technology compared with traditional drilling for caries removal. A systematic search was conducted through Medline via PubMed, Embase, Cochrane databases, CNKI till December 2016. Randomised controlled trials, quasi-randomized controlled trials, or controlled clinical trials with data comparing the efficacy of erbium laser technology versus traditional drilling for caries removal were included. Fourteen studies were selected in our meta-analysis. Erbium laser technology showed an increased time when removing caries compared with drilling (mean difference: 3.48, 95% confidence interval: 1.90-5.06, P < .0001). However, erbium laser technology reduced the requirement for local anesthesia (risk ratio: 0.28, 95% confidence interval: 0.13-0.62, P = .002). Erbium laser technology was also not significantly different to traditional drilling with regard to restoration loss, pulpal vitality, and postoperative sensitivity. Erbium laser technology showed an increased time for cavity preparation compared with traditional drilling. However, erbium laser technology reduced the requirement for local anesthesia. There was no significant difference between erbium laser technology and traditional drilling regarding restoration loss, pulpal vitality, and postoperative sensitivity. Copyright © 2017 Elsevier Inc. All rights reserved.

Laser application in neurosurgery

PubMed Central

Belykh, Evgenii; Yagmurlu, Kaan; Martirosyan, Nikolay L.; Lei, Ting; Izadyyazdanabadi, Mohammadhassan; Malik, Kashif M.; Byvaltsev, Vadim A.; Nakaji, Peter; Preul, Mark C.

2017-01-01

Background: Technological innovations based on light amplification created by stimulated emission of radiation (LASER) have been used extensively in the field of neurosurgery. Methods: We reviewed the medical literature to identify current laser-based technological applications for surgical, diagnostic, and therapeutic uses in neurosurgery. Results: Surgical applications of laser technology reported in the literature include percutaneous laser ablation of brain tissue, the use of surgical lasers in open and endoscopic cranial surgeries, laser-assisted microanastomosis, and photodynamic therapy for brain tumors. Laser systems are also used for intervertebral disk degeneration treatment, therapeutic applications of laser energy for transcranial laser therapy and nerve regeneration, and novel diagnostic laser-based technologies (e.g., laser scanning endomicroscopy and Raman spectroscopy) that are used for interrogation of pathological tissue. Conclusion: Despite controversy over the use of lasers for treatment, the surgical application of lasers for minimally invasive procedures shows promising results and merits further investigation. Laser-based microscopy imaging devices have been developed and miniaturized to be used intraoperatively for rapid pathological diagnosis. The multitude of ways that lasers are used in neurosurgery and in related neuroclinical situations is a testament to the technological advancements and practicality of laser science. PMID:29204309

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.

Mid-infrared absorption spectroscopy using quantum cascade lasers

NASA Astrophysics Data System (ADS)

Haibach, Fred; Erlich, Adam; Deutsch, Erik

2011-06-01

Block Engineering has developed an absorption spectroscopy system based on widely tunable Quantum Cascade Lasers (QCL). The QCL spectrometer rapidly cycles through a user-selected range in the mid-infrared spectrum, between 6 to 12 μm (1667 to 833 cm-1), to detect and identify substances on surfaces based on their absorption characteristics from a standoff distance of up to 2 feet with an eye-safe laser. It can also analyze vapors and liquids in a single device. For military applications, the QCL spectrometer has demonstrated trace explosive, chemical warfare agent (CWA), and toxic industrial chemical (TIC) detection and analysis. The QCL's higher power density enables measurements from diffuse and highly absorbing materials and substrates. Other advantages over Fourier Transform Infrared (FTIR) spectroscopy include portability, ruggedness, rapid analysis, and the ability to function from a distance through free space or a fiber optic probe. This paper will discuss the basic technology behind the system and the empirical data on various safety and security applications.

A novel design measuring method based on linearly polarized laser interference

NASA Astrophysics Data System (ADS)

Cao, Yanbo; Ai, Hua; Zhao, Nan

2013-09-01

The interferometric method is widely used in the precision measurement, including the surface quality of the large-aperture mirror. The laser interference technology has been developing rapidly as the laser sources become more and more mature and reliable. We adopted the laser diode as the source for the sake of the short coherent wavelength of it for the optical path difference of the system is quite shorter as several wavelengths, and the power of laser diode is sufficient for measurement and safe to human eye. The 673nm linearly laser was selected and we construct a novel form of interferometric system as we called `Closed Loop', comprised of polarizing optical components, such as polarizing prism and quartz wave plate, the light from the source split by which into measuring beam and referencing beam, they've both reflected by the measuring mirror, after the two beams transforming into circular polarization and spinning in the opposite directions we induced the polarized light synchronous phase shift interference technology to get the detecting fringes, which transfers the phase shifting in time domain to space, so that we did not need to consider the precise-controlled shift of optical path difference, which will introduce the disturbance of the air current and vibration. We got the interference fringes from four different CCD cameras well-alignment, and the fringes are shifted into four different phases of 0, π/2, π, and 3π/2 in time. After obtaining the images from the CCD cameras, we need to align the interference fringes pixel to pixel from different CCD cameras, and synthesis the rough morphology, after getting rid of systematic error, we could calculate the surface accuracy of the measuring mirror. This novel design detecting method could be applied into measuring the optical system aberration, and it would develop into the setup of the portable structural interferometer and widely used in different measuring circumstances.

Detection of trace explosives on relevant substrates using a mobile platform for photothermal infrared imaging spectroscopy (PT-IRIS)

NASA Astrophysics Data System (ADS)

Kendziora, Christopher A.; Furstenberg, Robert; Papantonakis, Michael; Nguyen, Viet; Byers, Jeff; McGill, R. Andrew

2015-05-01

This manuscript describes the results of recent tests regarding standoff detection of trace explosives on relevant substrates using a mobile platform. We are developing a technology for detection based on photo-thermal infrared (IR) imaging spectroscopy (PT-IRIS). This approach leverages one or more microfabricated IR quantum cascade lasers, tuned to strong absorption bands in the analytes and directed to illuminate an area on a surface of interest. An IR focal plane array is used to image the surface thermal emission upon laser illumination. The PT-IRIS signal is processed as a hyperspectral image cube comprised of spatial, spectral and temporal dimensions as vectors within a detection algorithm. Increased sensitivity to explosives and selectivity between different analyte types is achieved by narrow bandpass IR filters in the collection path. We have previously demonstrated the technique at several meters of stand-off distance indoors and in field tests, while operating the lasers below the infrared eye-safe intensity limit (100 mW/cm2). Sensitivity to explosive traces as small as a single 10 μm diameter particle (~1 ng) has been demonstrated. Analytes tested here include RDX, TNT, ammonium nitrate and sucrose. The substrates tested in this current work include metal, plastics, glass and painted car panels.

Towards computer-assisted TTTS: Laser ablation detection for workflow segmentation from fetoscopic video.

PubMed

Vasconcelos, Francisco; Brandão, Patrick; Vercauteren, Tom; Ourselin, Sebastien; Deprest, Jan; Peebles, Donald; Stoyanov, Danail

2018-06-27

Intrauterine foetal surgery is the treatment option for several congenital malformations. For twin-to-twin transfusion syndrome (TTTS), interventions involve the use of laser fibre to ablate vessels in a shared placenta. The procedure presents a number of challenges for the surgeon, and computer-assisted technologies can potentially be a significant support. Vision-based sensing is the primary source of information from the intrauterine environment, and hence, vision approaches present an appealing approach for extracting higher level information from the surgical site. In this paper, we propose a framework to detect one of the key steps during TTTS interventions-ablation. We adopt a deep learning approach, specifically the ResNet101 architecture, for classification of different surgical actions performed during laser ablation therapy. We perform a two-fold cross-validation using almost 50 k frames from five different TTTS ablation procedures. Our results show that deep learning methods are a promising approach for ablation detection. To our knowledge, this is the first attempt at automating photocoagulation detection using video and our technique can be an important component of a larger assistive framework for enhanced foetal therapies. The current implementation does not include semantic segmentation or localisation of the ablation site, and this would be a natural extension in future work.

Automated laser-based barely visible impact damage detection in honeycomb sandwich composite structures

NASA Astrophysics Data System (ADS)

Girolamo, D.; Girolamo, L.; Yuan, F. G.

2015-03-01

Nondestructive evaluation (NDE) for detection and quantification of damage in composite materials is fundamental in the assessment of the overall structural integrity of modern aerospace systems. Conventional NDE systems have been extensively used to detect the location and size of damages by propagating ultrasonic waves normal to the surface. However they usually require physical contact with the structure and are time consuming and labor intensive. An automated, contactless laser ultrasonic imaging system for barely visible impact damage (BVID) detection in advanced composite structures has been developed to overcome these limitations. Lamb waves are generated by a Q-switched Nd:YAG laser, raster scanned by a set of galvano-mirrors over the damaged area. The out-of-plane vibrations are measured through a laser Doppler Vibrometer (LDV) that is stationary at a point on the corner of the grid. The ultrasonic wave field of the scanned area is reconstructed in polar coordinates and analyzed for high resolution characterization of impact damage in the composite honeycomb panel. Two methodologies are used for ultrasonic wave-field analysis: scattered wave field analysis (SWA) and standing wave energy analysis (SWEA) in the frequency domain. The SWA is employed for processing the wave field and estimate spatially dependent wavenumber values, related to discontinuities in the structural domain. The SWEA algorithm extracts standing waves trapped within damaged areas and, by studying the spectrum of the standing wave field, returns high fidelity damage imaging. While the SWA can be used to locate the impact damage in the honeycomb panel, the SWEA produces damage images in good agreement with X-ray computed tomographic (X-ray CT) scans. The results obtained prove that the laser-based nondestructive system is an effective alternative to overcome limitations of conventional NDI technologies.

Biomedical Investigations with Laser-Polarized Noble Gas Magnetic Resonance

NASA Technical Reports Server (NTRS)

Walsworth, Ronald L.

2001-01-01

We are developing laser-polarized noble gas nuclear magnetic resonance (NMR) as a novel biomedical imaging tool for ground-based and eventually space-based application. This emerging multidisciplinary technology enables high-resolution gas-space magnetic resonance imaging (MRI) (e.g., of lung ventilation) as well as studies of tissue perfusion. In addition, laser-polarized noble gases (He-3 and Xe-129) do not require a large magnetic field for sensitive detection, opening the door to practical MRI at very low magnetic fields with an open, lightweight, and low-power device. We are pursuing two specific aims in this research. The first aim is to develop a low-field (< 0.01 T) instrument for noble gas MRI of humans, and the second aim is to develop functional MRI of the lung using laser-polarized Xe-129 and related techniques.

Miniaturized pulsed laser source for time-domain diffuse optics routes to wearable devices

NASA Astrophysics Data System (ADS)

Di Sieno, Laura; Nissinen, Jan; Hallman, Lauri; Martinenghi, Edoardo; Contini, Davide; Pifferi, Antonio; Kostamovaara, Juha; Mora, Alberto Dalla

2017-08-01

We validate a miniaturized pulsed laser source for use in time-domain (TD) diffuse optics, following rigorous and shared protocols for performance assessment of this class of devices. This compact source (12×6 mm2) has been previously developed for range finding applications and is able to provide short, high energy (˜100 ps, ˜0.5 nJ) optical pulses at up to 1 MHz repetition rate. Here, we start with a basic level laser characterization with an analysis of suitability of this laser for the diffuse optics application. Then, we present a TD optical system using this source and its performances in both recovering optical properties of tissue-mimicking homogeneous phantoms and in detecting localized absorption perturbations. Finally, as a proof of concept of in vivo application, we demonstrate that the system is able to detect hemodynamic changes occurring in the arm of healthy volunteers during a venous occlusion. Squeezing the laser source in a small footprint removes a key technological bottleneck that has hampered so far the realization of a miniaturized TD diffuse optics system, able to compete with already assessed continuous-wave devices in terms of size and cost, but with wider performance potentialities, as demonstrated by research over the last two decades.

Lidar instruments proposed for Eos

NASA Technical Reports Server (NTRS)

Grant, William B.; Browell, Edward V.

1990-01-01

Lidar, an acronym for light detection and ranging, represents a class of instruments that utilize lasers to send probe beams into the atmosphere or onto the surface of the Earth and detect the backscattered return in order to measure properties of the atmosphere or surface. The associated technology has matured to the point where two lidar facilities, Geodynamics Laser Ranging System (GLRS), and Laser Atmospheric Wind Sensor (LAWS) were accepted for Phase 2 studies for Eos. A third lidar facility Laser Atmospheric Sounder and Altimeter (LASA), with the lidar experiment EAGLE (Eos Atmospheric Global Lidar Experiment) was proposed for Eos. The generic lidar system has a number of components. They include controlling electronics, laser transmitters, collimating optics, a receiving telescope, spectral filters, detectors, signal chain electronics, and a data system. Lidar systems that measure atmospheric constituents or meteorological parameters record the signal versus time as the beam propagates through the atmosphere. The backscatter arises from molecular (Rayleigh) and aerosol (Mie) scattering, while attenuation arises from molecular and aerosol scattering and absorption. Lidar systems that measure distance to the Earth's surface or retroreflectors in a ranging mode record signals with high temporal resolution over a short time period. The overall characteristics and measurements objectives of the three lidar systems proposed for Eos are given.

Quantum cascade transmitters for ultrasensitive chemical agent and explosives detection

NASA Astrophysics Data System (ADS)

Schultz, John F.; Taubman, Matthew S.; Harper, Warren W.; Williams, Richard M.; Myers, Tanya L.; Cannon, Bret D.; Sheen, David M.; Anheier, Norman C., Jr.; Allen, Paul J.; Sundaram, S. K.; Johnson, Bradley R.; Aker, Pamela M.; Wu, Ming C.; Lau, Erwin K.

2003-07-01

The small size, high power, promise of access to any wavelength between 3.5 and 16 microns, substantial tuning range about a chosen center wavelength, and general robustness of quantum cascade (QC) lasers provide opportunities for new approaches to ultra-sensitive chemical detection and other applications in the mid-wave infrared. PNNL is developing novel remote and sampling chemical sensing systems based on QC lasers, using QC lasers loaned by Lucent Technologies. In recent months laboratory cavity-enhanced sensing experiments have achieved absorption sensitivities of 8.5 x 10-11 cm-1 Hz-1/2, and the PNNL team has begun monostatic and bi-static frequency modulated, differential absorption lidar (FM DIAL) experiments at ranges of up to 2.5 kilometers. In related work, PNNL and UCLA are developing miniature QC laser transmitters with the multiplexed tunable wavelengths, frequency and amplitude stability, modulation characteristics, and power levels needed for chemical sensing and other applications. Current miniaturization concepts envision coupling QC oscillators, QC amplifiers, frequency references, and detectors with miniature waveguides and waveguide-based modulators, isolators, and other devices formed from chalcogenide or other types of glass. Significant progress has been made on QC laser stabilization and amplification, and on development and characterization of high-purity chalcogenide glasses, waveguide writing techniques, and waveguide metrology.

New Diagnostic Aides for Melanoma

PubMed Central

Ferris, Laura K.; Harris, Ryan J.

2012-01-01

Synopsis Detection of melanoma at an early stage is crucial to improving survival rates in melanoma. Accurate diagnosis by current techniques including dermatoscopy remains difficult, and new tools are needed to improve our diagnostic abilities. This article discusses recent advances in diagnostic techniques including confocal scanning laser microscopy, MelaFind, Siascopy, noninvasive genomic detection, as well as other future possibilities to aid in diagnosing melanoma. Advantages and barriers to implementation of the various technologies are discussed as well. PMID:22800557

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

Fluorescence particle detector for real-time quantification of viable organisms in air

NASA Astrophysics Data System (ADS)

Luoma, Greg; Cherrier, Pierre P.; Piccioni, Marc; Tanton, Carol; Herz, Steve; DeFreez, Richard K.; Potter, Michael; Girvin, Kenneth L.; Whitney, Ronald

2002-02-01

The ability to detect viable organisms in air in real time is important in a number of applications. Detecting high levels of airborne organisms in hospitals can prevent post-operative infections and the spread of diseases. Monitoring levels of airborne viable organisms in pharmaceutical facilities can ensure safe production of drugs or vaccines. Monitoring airborne bacterial levels in meat processing plants can help to prevent contamination of food products. Monitoring the level of airborne organisms in bio-containment facilities can ensure that proper procedures are being followed. Finally, detecting viable organisms in real time is a key to defending against biological agent attacks. This presentation describes the development and performance of a detector, based on fluorescence particle counting technology, where an ultraviolet laser is used to count particles by light scattering and elicit fluorescence from specific biomolecules found only in living organisms. The resulting detector can specifically detect airborne particles containing living organisms from among the large majority of other particles normally present in air. Efforts to develop the core sensor technology, focusing on integrating an UV laser with a specially designed particle-counting cell will be highlighted. The hardware/software used to capture the information from the sensor, provide an alarm in the presence of an unusual biological aerosol content will also be described. Finally, results from experiments to test the performance of the detector will be presented.

Catalytic Converters Maintain Air Quality in Mines

NASA Technical Reports Server (NTRS)

2014-01-01

At Langley Research Center, engineers developed a tin-oxide based washcoat to prevent oxygen buildup in carbon dioxide lasers used to detect wind shears. Airflow Catalyst Systems Inc. of Rochester, New York, licensed the technology and then adapted the washcoat for use as a catalytic converter to treat the exhaust from diesel mining equipment.

UV lifetime laser demonstrator for space-based applications

NASA Astrophysics Data System (ADS)

Albert, Michael; Puffenburger, Kent; Schum, Tom; Fitzpatrick, Fran; Litvinovitch, Slava; Jones, Darrell; Rudd, Joseph; Hovis, Floyd

2015-09-01

A long-lived UV laser is an enabling technology for a number of high-priority, space-based lidar instruments. These include next generation cloud and aerosol lidars that incorporates a UV channel, direct detection 3-D wind lidars, and ozone DIAL (differential absorption lidar) system. In previous SBIR funded work we developed techniques for increasing the survivability of components in high power UV lasers and demonstrated improved operational lifetimes. In this Phase III ESTO funded effort we are designing and building a TRL (Technology Readiness Level) 6 demonstrator that will have increased output power and a space-qualifiable package that is mechanically robust and thermally-stable. For full space compatibility, thermal control will be through pure conductive cooling. Contamination control processes and optical coatings will be chosen that are compatible with lifetimes in excess of 1 billion shots. The 1064nm output will be frequency tripled to provide greater than 100mJ pulses of 355nm light at 150 Hz. After completing the laser module build in the third quarter of 2015 we will initiate lifetime testing, followed by thermal/vacuum (TVAC) and vibration testing to demonstrate that the design is at TRL 6.

Measurement of Concentration of CO2 in Atmosphere In Situ Based on TDLAS

NASA Astrophysics Data System (ADS)

Xin, Fengxin; Guo, Jinjia; Chen, Zhen; Liu, Zhishen

2014-11-01

As one of the main greenhouse gases in the atmosphere, CO2 has a significant impact on global climate change and the ecological environment. Because of close relationship between human activities and the CO2 emissions, it is very meaningful of detecting atmospheric CO2 accurately. Based on the technology of tunable diode laser absorption spectroscopy, the wavelength of distributed feedback laser is modulated, Fresnel lens is used as the receiving optical system, which receives the laser-beam reflected by corner reflector, and focuses the receiving laser-beam to the photoelectric detector. The second harmonic signal is received through lock-in amplifier and collected by AD data acquisition card, after that the system is built up. By choosing the infrared absorption line of CO2 at 1.57μm, the system is calibrated by 100% CO2 gas cell. The atmospheric CO2 in situ is measured with long open-path way. Furthermore, the results show that CO2 concentration decreases along time in the morning of day. It is proved that TDLAS technology has many advantages, including fast response, high sensitivity and resolution. This research provides a technique for monitoring secular change of CO2 in atmosphere.

Measurement of Concentration of CO2 in Atmosphere In Situ Based on TDLAS

NASA Astrophysics Data System (ADS)

Xin, Fengxin; Guo, Jinjia; Chen, Zhen; Liu, Zhishen

2014-11-01

As one of the main greenhouse gases in the atmosphere, CO2has a significant impact on global climate change and the ecological environment. Because of close relationship between human activities and the CO2 emissions, it is very meaningful of detecting atmospheric CO2accurately. Based on the technology of tunable diode laser absorption spectroscopy, the wavelength of distributed feedback laser is modulated, Fresnel lens is used as the receiving optical system, which receives the laser-beam reflected by corner reflector, and focuses the receiving laser-beam to the photoelectric detector. The second harmonic signal is received through lock-in amplifier and collected by AD data acquisition card, after that the system is built up.By choosing the infrared absorption line of CO2at 1.57μm, the system is calibrated by 100% CO2 gas cell. The atmospheric CO2 in situ is measured with long open-path way. Furthermore, the results show that CO2 concentration decreases along time in the morning of day. It is proved that TDLAS technology has many advantages, including fast response, high sensitivity and resolution. This research provides a technique for monitoring secular change of CO2 in atmosphere.

Long-range wind monitoring in real time with optimized coherent lidar

NASA Astrophysics Data System (ADS)

Dolfi-Bouteyre, Agnes; Canat, Guillaume; Lombard, Laurent; Valla, Matthieu; Durécu, Anne; Besson, Claudine

2017-03-01

Two important enabling technologies for pulsed coherent detection wind lidar are the laser and real-time signal processing. In particular, fiber laser is limited in peak power by nonlinear effects, such as stimulated Brillouin scattering (SBS). We report on various technologies that have been developed to mitigate SBS and increase peak power in 1.5-μm fiber lasers, such as special large mode area fiber designs or strain management. Range-resolved wind profiles up to a record range of 16 km within 0.1-s averaging time have been obtained thanks to those high-peak power fiber lasers. At long range, the lidar signal gets much weaker than the noise and special care is required to extract the Doppler peak from the spectral noise. To optimize real-time processing for weak carrier-to-noise ratio signal, we have studied various Doppler mean frequency estimators (MFE) and the influence of data accumulation on outliers occurrence. Five real-time MFEs (maximum, centroid, matched filter, maximum likelihood, and polynomial fit) have been compared in terms of error and processing time using lidar experimental data. MFE errors and data accumulation limits are established using a spectral method.

Space Solar Power Technology Demonstration for Lunar Polar Applications: Laser-Photovoltaic Wireless Power Transmission

NASA Technical Reports Server (NTRS)

Henley, M. W.; Fikes, J. C.; Howell, J.; Mankins, J. C.; Howell, Joe T. (Technical Monitor)

2002-01-01

Space Solar Power technology offers unique benefits for near-term NASA space science missions, which can mature this technology for other future applications. "Laser-Photo-Voltaic Wireless Power Transmission" (Laser-PV WPT) is a technology that uses a laser to beam power to a photovoltaic receiver, which converts the laser's light into electricity. Future Laser-PV WPT systems may beam power from Earth to satellites or large Space Solar Power satellites may beam power to Earth, perhaps supplementing terrestrial solar photo-voltaic receivers. In a near-term scientific mission to the moon, Laser-PV WPT can enable robotic operations in permanently shadowed lunar polar craters, which may contain ice. Ground-based technology demonstrations are proceeding, to mature the technology for this initial application, in the moon's polar regions.

Combining Frequency Doubling Technology Perimetry and Scanning Laser Polarimetry for Glaucoma Detection.

PubMed

Mwanza, Jean-Claude; Warren, Joshua L; Hochberg, Jessica T; Budenz, Donald L; Chang, Robert T; Ramulu, Pradeep Y

2015-01-01

To determine the ability of frequency doubling technology (FDT) and scanning laser polarimetry with variable corneal compensation (GDx-VCC) to detect glaucoma when used individually and in combination. One hundred ten normal and 114 glaucomatous subjects were tested with FDT C-20-5 screening protocol and the GDx-VCC. The discriminating ability was tested for each device individually and for both devices combined using GDx-NFI, GDx-TSNIT, number of missed points of FDT, and normal or abnormal FDT. Measures of discrimination included sensitivity, specificity, area under the curve (AUC), Akaike's information criterion (AIC), and prediction confidence interval lengths. For detecting glaucoma regardless of severity, the multivariable model resulting from the combination of GDx-TSNIT, number of abnormal points on FDT (NAP-FDT), and the interaction GDx-TSNIT×NAP-FDT (AIC: 88.28, AUC: 0.959, sensitivity: 94.6%, specificity: 89.5%) outperformed the best single-variable model provided by GDx-NFI (AIC: 120.88, AUC: 0.914, sensitivity: 87.8%, specificity: 84.2%). The multivariable model combining GDx-TSNIT, NAP-FDT, and interaction GDx-TSNIT×NAP-FDT consistently provided better discriminating abilities for detecting early, moderate, and severe glaucoma than the best single-variable models. The multivariable model including GDx-TSNIT, NAP-FDT, and the interaction GDx-TSNIT×NAP-FDT provides the best glaucoma prediction compared with all other multivariable and univariable models. Combining the FDT C-20-5 screening protocol and GDx-VCC improves glaucoma detection compared with using GDx or FDT alone.

Imaging of the optic nerve and retinal nerve fiber layer: an essential part of glaucoma diagnosis and monitoring.

PubMed

Kotowski, Jacek; Wollstein, Gadi; Ishikawa, Hiroshi; Schuman, Joel S

2014-01-01

Because glaucomatous damage is irreversible early detection of structural changes in the optic nerve head and retinal nerve fiber layer is imperative for timely diagnosis of glaucoma and monitoring of its progression. Significant improvements in ocular imaging have been made in recent years. Imaging techniques such as optical coherence tomography, scanning laser polarimetry and confocal scanning laser ophthalmoscopy rely on different properties of light to provide objective structural assessment of the optic nerve head, retinal nerve fiber layer and macula. In this review, we discuss the capabilities of these imaging modalities pertinent for diagnosis of glaucoma and detection of progressive glaucomatous damage and provide a review of the current knowledge on the clinical performance of these technologies. Copyright © 2014 Elsevier Inc. All rights reserved.

Widely tunable quantum cascade lasers for spectroscopic sensing

NASA Astrophysics Data System (ADS)

Wagner, J.; Ostendorf, R.; Grahmann, J.; Merten, A.; Hugger, S.; Jarvis, J.-P.; Fuchs, F.; Boskovic, D.; Schenk, H.

2015-01-01

In this paper recent advances in broadband-tuneable mid-infrared (MIR) external-cavity quantum cascade lasers (EC-QCL) technology are reported as well as their use in spectroscopic process analysis and imaging stand-off detection of hazardous substances, such as explosive and related precursors. First results are presented on rapid scan EC-QCL, employing a custom-made MOEMS scanning grating in Littrow-configuration as wavelength-selective optical feedback element. This way, a scanning rate of 1 kHz was achieved, which corresponds to 2000 full wavelength scans per second. Furthermore, exemplary case studies of EC-QCL based MIR spectroscopy will be presented. These include timeresolved analysis of catalytic reactions in chemical process control, as well as imaging backscattering spectroscopy for the detection of residues of explosives and related precursors in a relevant environment.

Intraoperative detection and elimination of microscopic tumors in head and neck (Conference Presentation)

NASA Astrophysics Data System (ADS)

Lukianova-Hleb, Ekaterina Y.; Kim, Yoo-Shin; Belatsarkouski, Ihar; Hanna, Ehab Y.; Gillenwater, Ann M.; O'Neill, Brian; Lapotko, Dmitri

2016-02-01

Failure of cancer surgery to intraoperatively detect and eliminate microscopic residual disease (MRD) causes lethal recurrence and metastases, whereas removal of important normal tissues causes excessive morbidity. We report plasmonic nanobubble (PNB) surgical technology to intraoperatively detect and eliminate MRD in surgical bed. PNBs were generated in vivo in head and neck cancer cells by systemically targeting tumor with gold colloids and locally-applied near-infrared low energy short laser pulse, and were simultaneously detected with acoustic probe. In mouse models of head and neck squamous cell carcinoma, single cancer cells and MRD (undetectable with standard histological methods) were instantaneously non-invasively detected in solid tissue in surgical bed. In resectable MRD, PNB-guided surgery prevented local recurrence and delivered 100% tumor-free survival. In unresectable MRD, PNB nano-surgery improved survival by two-fold compared to standard surgery. PNB metrics correlated with the tumor recurrence rate. PNB surgical technology precisely detects and immediately eliminates MRD at macro- and micro-scale in a simple and safe intraoperative procedure.

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.

Optical resolution photoacoustic microscopy using novel high-repetition-rate passively Q-switched microchip and fiber lasers.

PubMed

Shi, Wei; Kerr, Shaun; Utkin, Ilya; Ranasinghesagara, Janaka; Pan, Lei; Godwal, Yogesh; Zemp, Roger J; Fedosejevs, Robert

2010-01-01

Optical-resolution photoacoustic microscopy (OR-PAM) is a novel imaging technology for visualizing optically absorbing superficial structures in vivo with lateral spatial resolution determined by optical focusing rather than acoustic detection. Since scanning of the illumination spot is required, OR-PAM imaging speed is limited by both scanning speed and laser pulse repetition rate. Unfortunately, lasers with high repetition rates and suitable pulse durations and energies are not widely available and can be cost-prohibitive and bulky. We are developing compact, passively Q-switched fiber and microchip laser sources for this application. The properties of these lasers are discussed, and pulse repetition rates up to 100 kHz are demonstrated. OR-PAM imaging was conducted using a previously developed photoacoustic probe, which enabled flexible scanning of the focused output of the lasers. Phantom studies demonstrate the ability to image with lateral spatial resolution of 7±2 μm with the microchip laser system and 15±5 μm with the fiber laser system. We believe that the high pulse repetition rates and the potentially compact and fiber-coupled nature of these lasers will prove important for clinical imaging applications where real-time imaging performance is essential.

Laser-induced thermoelastic effects can evoke tactile sensations

NASA Astrophysics Data System (ADS)

Jun, Jae-Hoon; Park, Jong-Rak; Kim, Sung-Phil; Min Bae, Young; Park, Jang-Yeon; Kim, Hyung-Sik; Choi, Seungmoon; Jung, Sung Jun; Hwa Park, Seung; Yeom, Dong-Il; Jung, Gu-In; Kim, Ji-Sun; Chung, Soon-Cheol

2015-06-01

Humans process a plethora of sensory information that is provided by various entities in the surrounding environment. Among the five major senses, technology for touch, haptics, is relatively young and has relatively limited applications largely due to its need for physical contact. In this article, we suggest a new way for non-contact haptic stimulation that uses laser, which has potential advantages such as mid-air stimulation, high spatial precision, and long working distance. We demonstrate such tactile stimulation can be enabled by laser-induced thermoelastic effects by means of physical and perceptual studies, as well as simulations. In the physical study, the mechanical effect of laser on a human skin sample is detected using low-power radiation in accordance with safety guidelines. Limited increases (< ~2.5 °C) in temperature at the surface of the skin, examined by both thermal camera and the Monte Carlo simulation, indicate that laser does not evoke heat-induced nociceptive sensation. In the human EEG study, brain responses to both mechanical and laser stimulation are consistent, along with subjective reports of the non-nociceptive sensation of laser stimuli.

Laser-induced thermoelastic effects can evoke tactile sensations.

PubMed

Jun, Jae-Hoon; Park, Jong-Rak; Kim, Sung-Phil; Min Bae, Young; Park, Jang-Yeon; Kim, Hyung-Sik; Choi, Seungmoon; Jung, Sung Jun; Hwa Park, Seung; Yeom, Dong-Il; Jung, Gu-In; Kim, Ji-Sun; Chung, Soon-Cheol

2015-06-05

Humans process a plethora of sensory information that is provided by various entities in the surrounding environment. Among the five major senses, technology for touch, haptics, is relatively young and has relatively limited applications largely due to its need for physical contact. In this article, we suggest a new way for non-contact haptic stimulation that uses laser, which has potential advantages such as mid-air stimulation, high spatial precision, and long working distance. We demonstrate such tactile stimulation can be enabled by laser-induced thermoelastic effects by means of physical and perceptual studies, as well as simulations. In the physical study, the mechanical effect of laser on a human skin sample is detected using low-power radiation in accordance with safety guidelines. Limited increases (< ~2.5 °C) in temperature at the surface of the skin, examined by both thermal camera and the Monte Carlo simulation, indicate that laser does not evoke heat-induced nociceptive sensation. In the human EEG study, brain responses to both mechanical and laser stimulation are consistent, along with subjective reports of the non-nociceptive sensation of laser stimuli.

A reagentless real-time method for the multiparameter analysis of nanoparticles as a potential 'trigger' device

NASA Astrophysics Data System (ADS)

Carr, Bob; Knowles, John; Warren, Jeremy

2008-10-01

We describe the continuing development of a laser-based, light scattering detector system capable of detecting and analysing liquid-borne nanoparticles. Using a finely focussed and specially configured laser beam to illuminate a suspension of nanoparticles in a small (250ul) sample and videoing the Brownian motion of each and every particle in the detection zone should allow individual but simultaneous detection and measurement of particle size, scattered light intensity, electrophoretic mobility and, where applicable, shape asymmetry. This real-time, multi-parameter analysis capability offers the prospect of reagentlessly differentiating between different particle types within a complex sample of potentially high and variable background. Employing relatively low powered (50-100mW) laser diode modules and low resolution CCD arrays, each component could be run off battery power, allowing distributed/remote or personal deployment. Voltages needed for electrophoresis measurement s would be similarly low (e.g. 20V, low current) and 30second videos (exported at mobile/cell phone download speeds) analysed remotely. The potential of such low-cost technology as a field-deployable grid of remote, battery powered and reagentless, multi-parameter sensors for use as trigger devices is discussed.

Performance of a fire detector based on a compact laser spectroscopic carbon monoxide sensor.

PubMed

Hangauer, A; Chen, J; Strzoda, R; Fleischer, M; Amann, M-C

2014-06-02

In this paper we show the suitability of a miniaturized tunable diode laser spectroscopy (TDLS)-based carbon-monoxide (CO) sensor for fire detection applications. The sensor utilizes a vertical-cavity surface-emitting laser (VCSEL) and inherent calibration scheme with reference gas filled in the photodetector housing. The fire-detection experiments are carried out under realistic conditions as described in the European standard EN54. The CO generation of all class C fires (according to EN54) could be well resolved. The cross-sensitivity to other substances was found to be very low: the maximum CO false response from cigarette smoke, hairspray and general aerosols reaches a low value of a few μL/L and only if the substance is directly applied into the sensor gas inlet. Therefore this sensor overcomes the disadvantage of high false alarm rate given by smoke detectors and is also in small size which is suitable for household and industrial applications. Hence, the VCSEL-based TDLS sensor is shown to have sufficient performance for fire-detection. It has advantages such as capability for fail-safe operation and, low cross-sensitivities as compared to existing point fire detector technology which is presently limited by these factors.

Mid-Infrared Trace Gas Sensor Technology Based on Intracavity Quartz-Enhanced Photoacoustic Spectroscopy.

PubMed

Wojtas, Jacek; Gluszek, Aleksander; Hudzikowski, Arkadiusz; Tittel, Frank K

2017-03-04

The application of compact inexpensive trace gas sensor technology to a mid-infrared nitric oxide (NO) detectoion using intracavity quartz-enhanced photoacoustic spectroscopy (I-QEPAS) is reported. A minimum detection limit of 4.8 ppbv within a 30 ms integration time was demonstrated by using a room-temperature, continuous-wave, distributed-feedback quantum cascade laser (QCL) emitting at 5.263 µm (1900.08 cm -1 ) and a new compact design of a high-finesse bow-tie optical cavity with an integrated resonant quartz tuning fork (QTF). The optimum configuration of the bow-tie cavity was simulated using custom software. Measurements were performed with a wavelength modulation scheme (WM) using a 2f detection procedure.

Random Sequence for Optimal Low-Power Laser Generated Ultrasound

NASA Astrophysics Data System (ADS)

Vangi, D.; Virga, A.; Gulino, M. S.

2017-08-01

Low-power laser generated ultrasounds are lately gaining importance in the research world, thanks to the possibility of investigating a mechanical component structural integrity through a non-contact and Non-Destructive Testing (NDT) procedure. The ultrasounds are, however, very low in amplitude, making it necessary to use pre-processing and post-processing operations on the signals to detect them. The cross-correlation technique is used in this work, meaning that a random signal must be used as laser input. For this purpose, a highly random and simple-to-create code called T sequence, capable of enhancing the ultrasound detectability, is introduced (not previously available at the state of the art). Several important parameters which characterize the T sequence can influence the process: the number of pulses Npulses , the pulse duration δ and the distance between pulses dpulses . A Finite Element FE model of a 3 mm steel disk has been initially developed to analytically study the longitudinal ultrasound generation mechanism and the obtainable outputs. Later, experimental tests have shown that the T sequence is highly flexible for ultrasound detection purposes, making it optimal to use high Npulses and δ but low dpulses . In the end, apart from describing all phenomena that arise in the low-power laser generation process, the results of this study are also important for setting up an effective NDT procedure using this technology.

Advanced endoscopic imaging in gastric neoplasia and preneoplasia

PubMed Central

Lee, Jonathan W J; Lim, Lee Guan; Yeoh, Khay Guan

2017-01-01

Conventional white light endoscopy remains the current standard in routine clinical practice for early detection of gastric cancer. However, it may not accurately diagnose preneoplastic gastric lesions. The technological advancements in the field of endoscopic imaging for gastric lesions are fast growing. This article reviews currently available advanced endoscopic imaging modalities, in particular chromoendoscopy, narrow band imaging and confocal laser endomicroscopy, and their corresponding evidence shown to improve diagnosis of preneoplastic gastric lesions. Raman spectrometry and polarimetry are also introduced as promising emerging technologies. PMID:28176895

Solid state laser technology - A NASA perspective

NASA Technical Reports Server (NTRS)

Allario, F.

1985-01-01

NASA's program for developing solid-state laser technology and applying it to the Space Shuttle and Space Platform is discussed. Solid-state lasers are required to fulfill the Earth Observation System's requirements. The role of the Office of Aeronautics and Space Technology in developing a NASA tunable solid-state laser program is described. The major goals of the program involve developing a solid-state pump laser in the green, using AlGaAs array technology, pumping a Nd:YAG/SLAB crystal or glass, and fabricating a lidar system, with either a CO2 laser at 10.6 microns or a Nd:YAG laser at 1.06 microns, to measure tropospheric winds to an accuracy of + or - 1 m/s and a vertical resolution of 1 km. The procedures to be followed in order to visualize this technology plan include: (1) material development and characterization, (2) laser development, and (3) implementation of the lasers.

Laser ablated micropillar energy directors for ultrasonic welding of microfluidic systems

NASA Astrophysics Data System (ADS)

Esben Poulsen, Carl; Kistrup, Kasper; Korsgaard Andersen, Nis; Taboryski, Rafael; Fougt Hansen, Mikkel; Wolff, Anders

2016-06-01

We present a new type of energy director (ED) for ultrasonic welding of microfluidic systems. These micropillar EDs are based on the replication of cone like protrusion structures introduced using a pico-second laser and may therefore be added to any mould surface accessible to a pico-second laser beam. The technology is demonstrated on an injection moulded microfluidic device featuring high-aspect ratio (h  ×  w  =  2000 μm  ×  550 μm) and free-standing channel walls, where bonding is achieved with no detectable channel deformation. The bonding strength is similar to conventional EDs and the fabricated system can withstand pressures of over 9.5 bar.

Characterization of turbulent wake of wind turbine by coherent Doppler lidar

NASA Astrophysics Data System (ADS)

Wu, Songhua; Yin, Jiaping; Liu, Bingyi; Liu, Jintao; Li, Rongzhong; Wang, Xitao; Feng, Changzhong; Zhuang, Quanfeng; Zhang, Kailin

2014-11-01

The indispensable access to real turbulent wake behavior is provided by the pulsed coherent Doppler Light Detection and Ranging (LIDAR) which operates by transmitting a laser beam and detecting the radiation backscattered by atmospheric aerosol particles. The Doppler shift in the frequency of the backscattered signal is analyzed to obtain the line-of-sight (LOS) velocity component of the air motion. From the LOS velocities the characteristic of the turbulent wake can be deduced. The Coherent Doppler LIDAR (CDL) is based on all-fiber laser technology and fast digital-signal-processing technology. The 1.5 µm eye-safe Doppler LIDAR system has a pulse length of 200ns and a pulse repetition frequency of 10 kHz. The speed measurement range is ±50m/s and the speed measurement uncertainty is 0.3 m/s. The 2-axis beam scanner and detection range of 3000m enable the system to monitor the whole wind farming filed. Because of the all-fiber structure adoption, the system is stable, reliable and high-integrated. The wake vortices of wind turbine blades with different spatial and temporal scales have been observed by LIDAR. In this paper, the authors discuss the possibility of using LIDAR measurements to characterize the complicated wind field, specifically wind velocity deficit and terrain effects.

MALDI-TOF mass spectrometry: an emerging technology for microbial identification and diagnosis

PubMed Central

Singhal, Neelja; Kumar, Manish; Kanaujia, Pawan K.; Virdi, Jugsharan S.

2015-01-01

Currently microorganisms are best identified using 16S rRNA and 18S rRNA gene sequencing. However, in recent years matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has emerged as a potential tool for microbial identification and diagnosis. During the MALDI-TOF MS process, microbes are identified using either intact cells or cell extracts. The process is rapid, sensitive, and economical in terms of both labor and costs involved. The technology has been readily imbibed by microbiologists who have reported usage of MALDI-TOF MS for a number of purposes like, microbial identification and strain typing, epidemiological studies, detection of biological warfare agents, detection of water- and food-borne pathogens, detection of antibiotic resistance and detection of blood and urinary tract pathogens etc. The limitation of the technology is that identification of new isolates is possible only if the spectral database contains peptide mass fingerprints of the type strains of specific genera/species/subspecies/strains. This review provides an overview of the status and recent applications of mass spectrometry for microbial identification. It also explores the usefulness of this exciting new technology for diagnosis of diseases caused by bacteria, viruses, and fungi. PMID:26300860

MALDI-TOF mass spectrometry: an emerging technology for microbial identification and diagnosis.

PubMed

Singhal, Neelja; Kumar, Manish; Kanaujia, Pawan K; Virdi, Jugsharan S

2015-01-01

Currently microorganisms are best identified using 16S rRNA and 18S rRNA gene sequencing. However, in recent years matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has emerged as a potential tool for microbial identification and diagnosis. During the MALDI-TOF MS process, microbes are identified using either intact cells or cell extracts. The process is rapid, sensitive, and economical in terms of both labor and costs involved. The technology has been readily imbibed by microbiologists who have reported usage of MALDI-TOF MS for a number of purposes like, microbial identification and strain typing, epidemiological studies, detection of biological warfare agents, detection of water- and food-borne pathogens, detection of antibiotic resistance and detection of blood and urinary tract pathogens etc. The limitation of the technology is that identification of new isolates is possible only if the spectral database contains peptide mass fingerprints of the type strains of specific genera/species/subspecies/strains. This review provides an overview of the status and recent applications of mass spectrometry for microbial identification. It also explores the usefulness of this exciting new technology for diagnosis of diseases caused by bacteria, viruses, and fungi.

Efficient generation of twin photons at telecom wavelengths with 2.5 GHz repetition-rate-tunable comb laser.

PubMed

Jin, Rui-Bo; Shimizu, Ryosuke; Morohashi, Isao; Wakui, Kentaro; Takeoka, Masahiro; Izumi, Shuro; Sakamoto, Takahide; Fujiwara, Mikio; Yamashita, Taro; Miki, Shigehito; Terai, Hirotaka; Wang, Zhen; Sasaki, Masahide

2014-12-19

Efficient generation and detection of indistinguishable twin photons are at the core of quantum information and communications technology (Q-ICT). These photons are conventionally generated by spontaneous parametric down conversion (SPDC), which is a probabilistic process, and hence occurs at a limited rate, which restricts wider applications of Q-ICT. To increase the rate, one had to excite SPDC by higher pump power, while it inevitably produced more unwanted multi-photon components, harmfully degrading quantum interference visibility. Here we solve this problem by using recently developed 10 GHz repetition-rate-tunable comb laser, combined with a group-velocity-matched nonlinear crystal, and superconducting nanowire single photon detectors. They operate at telecom wavelengths more efficiently with less noises than conventional schemes, those typically operate at visible and near infrared wavelengths generated by a 76 MHz Ti Sapphire laser and detected by Si detectors. We could show high interference visibilities, which are free from the pump-power induced degradation. Our laser, nonlinear crystal, and detectors constitute a powerful tool box, which will pave a way to implementing quantum photonics circuits with variety of good and low-cost telecom components, and will eventually realize scalable Q-ICT in optical infra-structures.

Radiation Detection Center on the Front Lines

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

Hazi, A

2005-09-20

Many of today's radiation detection tools were developed in the 1960s. For years, the Laboratory's expertise in radiation detection resided mostly within its nuclear test program. When nuclear testing was halted in the 1990s, many of Livermore's radiation detection experts were dispersed to other parts of the Laboratory, including the directorates of Chemistry and Materials Science (CMS); Physics and Advanced Technologies (PAT); Defense and Nuclear Technologies (DNT); and Nonproliferation, Arms Control, and International Security (NAI). The RDC was formed to maximize the benefit of radiation detection technologies being developed in 15 to 20 research and development (R&D) programs. These effortsmore » involve more than 200 Laboratory employees across eight directorates, in areas that range from electronics to computer simulations. The RDC's primary focus is the detection, identification, and analysis of nuclear materials and weapons. A newly formed outreach program within the RDC is responsible for conducting radiation detection workshops and seminars across the country and for coordinating university student internships. Simon Labov, director of the RDC, says, ''Virtually all of the Laboratory's programs use radiation detection devices in some way. For example, DNT uses radiation detection to create radiographs for their work in stockpile stewardship and in diagnosing explosives; CMS uses it to develop technology for advancing the detection, diagnosis, and treatment of cancer; and the Energy and Environment Directorate uses radiation detection in the Marshall Islands to monitor the aftermath of nuclear testing in the Pacific. In the future, the National Ignition Facility will use radiation detection to probe laser targets and study shock dynamics.''« less

Emerging fiber optic endomicroscopy technologies towards noninvasive real-time visualization of histology in situ

NASA Astrophysics Data System (ADS)

Xi, Jiefeng; Zhang, Yuying; Huo, Li; Chen, Yongping; Jabbour, Toufic; Li, Ming-Jun; Li, Xingde

2010-09-01

This paper reviews our recent developments of ultrathin fiber-optic endomicroscopy technologies for transforming high-resolution noninvasive optical imaging techniques to in vivo and clinical applications such as early disease detection and guidance of interventions. Specifically we describe an all-fiber-optic scanning endomicroscopy technology, which miniaturizes a conventional bench-top scanning laser microscope down to a flexible fiber-optic probe of a small footprint (i.e. ~2-2.5 mm in diameter), capable of performing two-photon fluorescence and second harmonic generation microscopy in real time. This technology aims to enable realtime visualization of histology in situ without the need for tissue removal. We will also present a balloon OCT endoscopy technology which permits high-resolution 3D imaging of the entire esophagus for detection of neoplasia, guidance of biopsy and assessment of therapeutic outcome. In addition we will discuss the development of functional polymeric fluorescent nanocapsules, which use only FAD approved materials and potentially enable fast track clinical translation of optical molecular imaging and targeted therapy.

Study on off-axis detection of pulsed laser in atmosphere

NASA Astrophysics Data System (ADS)

Liang, Weiwei

2018-02-01

Laser communication, designation, and ranging are point to point and have a high degree of specificity, current laser detection, such as laser warning receiver system, could detect the scattering laser from the off-axis distance by scattering track on natural aerosols, which is helpful to locate the laser source. However, the intensity of the scattering laser is extremely weak and affected by many factors, in order to evaluate the detection characteristic, a simplified model of off-axis detection for scattering laser in the lower atmosphere based on the Mie scattering theory is presented in this paper, the performances of the off-axis laser detection in different conditions such as off-axis distance, visibility, incidence angle, and delay time are investigated.

Security training with interactive laser-video-disk technology

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

Wilson, D.

1988-01-01

DOE, through its contractor EG and G Energy Measurements, Inc., has developed a state-of-the-art interactive-video system for use at the Department of Energy's Central Training Academy. Called the Security Training and Evaluation Shooting System (STRESS), the computer-driven decision shooting system employs the latest is laservideo-disk technology. STRESS is designed to provide realistic and stressful training for security inspectors employed by the DOE and its contractors. The system uses wide-screen video projection, sophisticated scenario-branching technology, and customized video scenarios especially designed for the DOE. Firing a weapon that has been modified to shoot ''laser bullets,'' and wearing a special vest thatmore » detects ''hits'': the security inspector encounters adversaries on the wide screen who can shoot or be shot by the inspector in scenarios that demand fast decisions. Based on those decisions, the computer provides instantaneous branching to different scenes, giving the inspector confrontational training with the realism and variability of real life.« less

21 CFR 872.1745 - Laser fluorescence caries detection device.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Laser fluorescence caries detection device. 872... SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Diagnostic Devices § 872.1745 Laser fluorescence caries detection device. (a) Identification. A laser fluorescence caries detection device is a laser, a...

Characterization of Kevlar Using Raman Spectroscopy

NASA Technical Reports Server (NTRS)

Washer, Glenn; Brooks, Thomas; Saulsberry, Regor

2007-01-01

This paper explores the characterization of Kevlar composite materials using Raman spectroscopy. The goal of the research is to develop and understand the Raman spectrum of Kevlar materials to provide a foundation for the development of nondestructive evaluation (NDE) technologies based on the interaction of laser light with the polymer Kevlar. The paper discusses the fundamental aspects of experimental characterization of the spectrum of Kevlar, including the effects of incident wavelength, polarization and laser power. The effects of environmental exposure of Kevlar materials on certain characteristics of its Raman spectrum are explored, as well as the effects of applied stress. This data may provide a foundation for the development of NDE technologies intended to detect the in-situ deterioration of Kevlar materials used for engineering applications that can later be extended to other materials such as carbon fiber composites.

Potential technology transfers of research on low-temperature carbon monoxide-oxygen recombination catalysts

NASA Technical Reports Server (NTRS)

Poziomek, Edward J.

1990-01-01

Results from research on catalytic recombination of CO-O2 for stable closed-cycle operation of CO2 lasers hold much promise for a variety of technology transfer. Expansion of CO2 laser remote sensing applications toward chemical detection and pollution monitoring would certainly be expected. However, the catalysts themselves may be especially effective in low-temperature oxidation of a number of chemicals in addition to CO. It is therefore of interest to compare the CO-O2 catalysts with chemical systems designed for chemical sensing, air purification and process catalysis. Success in understanding the catalytic mechanisms of the recombination of CO-O2 could help to shed light on how catalyst systems operate. New directions in low-temperature oxidation catalysts, coatings for chemical sensors and sorbents for air purification could well emerge.

The simulation study on optical target laser active detection performance

NASA Astrophysics Data System (ADS)

Li, Ying-chun; Hou, Zhao-fei; Fan, Youchen

2014-12-01

According to the working principle of laser active detection system, the paper establishes the optical target laser active detection simulation system, carry out the simulation study on the detection process and detection performance of the system. For instance, the performance model such as the laser emitting, the laser propagation in the atmosphere, the reflection of optical target, the receiver detection system, the signal processing and recognition. We focus on the analysis and modeling the relationship between the laser emitting angle and defocus amount and "cat eye" effect echo laser in the reflection of optical target. Further, in the paper some performance index such as operating range, SNR and the probability of the system have been simulated. The parameters including laser emitting parameters, the reflection of the optical target and the laser propagation in the atmosphere which make a great influence on the performance of the optical target laser active detection system. Finally, using the object-oriented software design methods, the laser active detection system with the opening type, complete function and operating platform, realizes the process simulation that the detection system detect and recognize the optical target, complete the performance simulation of each subsystem, and generate the data report and the graph. It can make the laser active detection system performance models more intuitive because of the visible simulation process. The simulation data obtained from the system provide a reference to adjust the structure of the system parameters. And it provides theoretical and technical support for the top level design of the optical target laser active detection system and performance index optimization.

Functionalized xenon as a biosensor

PubMed Central

Spence, Megan M.; Rubin, Seth M.; Dimitrov, Ivan E.; Ruiz, E. Janette; Wemmer, David E.; Pines, Alexander; Yao, Shao Qin; Tian, Feng; Schultz, Peter G.

2001-01-01

The detection of biological molecules and their interactions is a significant component of modern biomedical research. In current biosensor technologies, simultaneous detection is limited to a small number of analytes by the spectral overlap of their signals. We have developed an NMR-based xenon biosensor that capitalizes on the enhanced signal-to-noise, spectral simplicity, and chemical-shift sensitivity of laser-polarized xenon to detect specific biomolecules at the level of tens of nanomoles. We present results using xenon “functionalized” by a biotin-modified supramolecular cage to detect biotin–avidin binding. This biosensor methodology can be extended to a multiplexing assay for multiple analytes. PMID:11535830

Performance status of a small robot-mounted or hand-held, solar-blind, standoff chemical, biological, and explosives (CBE) sensor

NASA Astrophysics Data System (ADS)

Hug, W. F.; Reid, R. D.; Bhartia, R.; Lane, A. L.

2009-05-01

Photon Systems and JPL are continuing development of a new technology robot-mounted or hand-held sensor for reagentless, short-range, standoff detection and identification of trace levels CBE materials on surfaces. This deep ultraviolet CBE sensor is the result of ongoing Army STTR and DTRA programs. The evolving 6 lb, 15W, lantern-size sensor can discriminate CBE from background clutter materials using a combination of deep UV excited resonance Raman (RR) and laser induced native fluorescence (LINF) emissions resulting from excitation by a new technology deep UV laser. Standoff excitation of suspicious packages, vehicles, persons, and other objects that may contain hazardous materials is accomplished using wavelengths below 250nm where RR and LINF emissions occupy distinctly different wavelength regions. This enables simultaneous detection of RR and LINF emissions with no spectral overlap or interference of LINF over RR or RR over LINF. The new eye-safe targeted ultraviolet chemical, biological, and explosives (TUCBE) sensor can detect and identify less than 1 μg/cm2 of explosives or 104 bacterial spores at 10 meters standoff, or 10 ng/cm2 of explosives or 102 bacterial spores/cm2 at 1 meter standoff. Detection and identification requires less than 1 ms and has a sample rate up to 20 Hz. Lower concentrations of contamination can be detected and identified as closer ranges and higher concentrations at longer ranges. The sensor is solar blind and can be operated in full daylight conditions as a result of excitation and detection in the deep UV and the use of a gated detection system.

Color speckle in laser displays

NASA Astrophysics Data System (ADS)

Kuroda, Kazuo

2015-07-01

At the beginning of this century, lighting technology has been shifted from discharge lamps, fluorescent lamps and electric bulbs to solid-state lighting. Current solid-state lighting is based on the light emitting diodes (LED) technology, but the laser lighting technology is developing rapidly, such as, laser cinema projectors, laser TVs, laser head-up displays, laser head mounted displays, and laser headlamps for motor vehicles. One of the main issues of laser displays is the reduction of speckle noise1). For the monochromatic laser light, speckle is random interference pattern on the image plane (retina for human observer). For laser displays, RGB (red-green-blue) lasers form speckle patterns independently, which results in random distribution of chromaticity, called color speckle2).

Chromoendoscopy and Advanced Imaging Technologies for Surveillance of Patients with IBD

PubMed Central

Barkin, Jodie A.; Abreu, Maria T.

2012-01-01

Inflammatory bowel disease patients with long-standing colitis have an increased risk of colorectal cancer. The high rate of interval colitis-associated cancers among patients who adhere to a nontargeted, random biopsy surveillance strategy underlies the need for improved methods of early dysplasia detection. Compelling evidence supports the efficacy of chromoendoscopy for increasing the detection rate of dysplasia; however, this technology is currently underutilized in the clinical setting. Other contrast-based technologies—including confocal laser endomicroscopy (Pentax), endocytoscopy, multiband imaging, i-scan (Pentax), and molecular-targeted techniques—show promise in the detection of dysplasia in patients with inflammatory bowel disease. The strategies currently available for identifying patients with dysplasia or colitis-associated cancers remain inadequate and need to demonstrate both cost and time efficiency before they can be adopted in community-based practices. PMID:24693269

2-Micron Coherent Doppler Lidar Instrument Advancements for Tropospheric Wind Measurement

NASA Technical Reports Server (NTRS)

Petros, Mulugeta; Singh, U. N.; Yu, J.; Kavaya, M. J.; Koch, G.

2014-01-01

Knowledge derived from global tropospheric wind measurement is an important constituent of our overall understanding of climate behavior [1]. Accurate weather prediction saves lives and protects properties from destructions. High-energy 2-micron laser is the transmitter of choice for coherent Doppler wind detection. In addition to the eye-safety, the wavelength of the transmitter suitably matches the aerosol size in the lower troposphere. Although the technology of the 2-micron laser has been maturing steadily, lidar derived wind data is still a void in the global weather database. In the last decade, researchers at NASA Langley Research Center (LaRC) have been engaged in this endeavor, contributing to the scientific database of 2-micron lidar transmitters. As part of this effort, an in depth analysis of the physics involved in the workings of the Ho: Tm laser systems have been published. In the last few years, we have demonstrated lidar transmitter with over1Joule output energy. In addition, a large body of work has been done in characterizing new laser materials and unique crystal configurations to enhance the efficiency and output energy of the 2-micron laser systems. At present 2-micron lidar systems are measuring wind from both ground and airborne platforms. This paper will provide an overview of the advancements made in recent years and the technology maturity levels attained.

Elimination of leukemic cells from human transplants by laser nano-thermolysis

NASA Astrophysics Data System (ADS)

Lapotko, Dmitri; Lukianova, Ekaterina; Potapnev, Michail; Aleinikova, Olga; Oraevsky, Alexander

2006-02-01

We describe novel ex vivo method for elimination of tumor cells from bone marrow and blood, Laser Activated Nano-Thermolysis for Cell Elimination Technology (LANTCET) and propose this method for purging of transplants during treatment of leukemia. Human leukemic cells derived from real patients with different diagnoses (acute lymphoblastic leukemias) were selectively damaged by LANTCET in the experiments by laser-induced micro-bubbles that emerge inside individual specifically-targeted cells around the clusters of light-absorbing gold nanoparticles. Pretreatment of the transplants with diagnosis-specific primary monoclonal antibodies and gold nano-particles allowed the formation of nanoparticle clusters inside leukemic cells only. Electron microscopy found the nanoparticulate clusters inside the cells. Total (99.9%) elimination of leukemic cells targeted with specific antibodies and nanoparticles was achieved with single 10-ns laser pulses with optical fluence of 0.2 - 1.0 J/cm2 at the wavelength of 532 nm without significant damage to normal bone marrow cells in the same transplant. All cells were studied for the damage/viability with several control methods after their irradiation by laser pulses. Presented results have proved potential applicability of developed LANTCET technology for efficient and safe purging (cleaning of residual tumor cells) of human bone marrow and blood transplants. Design of extra-corporeal system was proposed that can process the transplant for one patient for less than an hour with parallel detection and counting residual leukemic cells.

eSensor: an electrochemical detection-based DNA microarray technology enabling sample-to-answer molecular diagnostics

NASA Astrophysics Data System (ADS)

Liu, Robin H.; Longiaru, Mathew

2009-05-01

DNA microarrays are becoming a widespread tool used in life science and drug screening due to its many benefits of miniaturization and integration. Microarrays permit a highly multiplexed DNA analysis. Recently, the development of new detection methods and simplified methodologies has rapidly expanded the use of microarray technologies from predominantly gene expression analysis into the arena of diagnostics. Osmetech's eSensor® is an electrochemical detection platform based on a low-to- medium density DNA hybridization array on a cost-effective printed circuit board substrate. eSensor® has been cleared by FDA for Warfarin sensitivity test and Cystic Fibrosis Carrier Detection. Other genetic-based diagnostic and infectious disease detection tests are under development. The eSensor® platform eliminates the need for an expensive laser-based optical system and fluorescent reagents. It allows one to perform hybridization and detection in a single and small instrument without any fluidic processing and handling. Furthermore, the eSensor® platform is readily adaptable to on-chip sample-to-answer genetic analyses using microfluidics technology. The eSensor® platform provides a cost-effective solution to direct sample-to-answer genetic analysis, and thus have a potential impact in the fields of point-of-care genetic analysis, environmental testing, and biological warfare agent detection.

Single-shot measurement of >1010 pulse contrast for ultra-high peak-power lasers

PubMed Central

Wang, Yongzhi; Ma, Jingui; Wang, Jing; Yuan, Peng; Xie, Guoqiang; Ge, Xulei; Liu, Feng; Yuan, Xiaohui; Zhu, Heyuan; Qian, Liejia

2014-01-01

Real-time pulse-contrast observation with a high dynamic range is a prerequisite to tackle the contrast challenge in ultra-high peak-power lasers. However, the commonly used delay-scanning cross-correlator (DSCC) can only provide the time-consumed measurements for repetitive lasers. Single-shot cross-correlator (SSCC) becomes essential in optimizing laser systems and exploring contrast mechanisms. Here we report our progress in developing SSCC towards its practical use. By integrating both the techniques of scattering-noise reduction and sensitive parallel detection into SSCC, we demonstrate a high dynamic range of >1010, which, to our best knowledge, is the first demonstration of an SSCC with a dynamic range comparable to that of commercial DSCCs. The comparison of high-dynamic measurement performances between SSCC and a standard DSCC (Sequoia, Amplitude Technologies) is also carried out on a 200 TW Ti:sapphire laser, and the consistency of results verifies the veracity of our SSCC. PMID:24448655

Development of a Landmine Detection Sensor Final Report CRADA No. TC02133.0

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

Romero, C. E.; Sheppard, C.

2017-09-06

This was one of two CRADAs between Lawrence Livermore National Security, LLC as manager and operator of Lawrence Livermore National Laboratory (LLNL) and First Alliance Technologies, LLC (First Alliance), to conduct research and development activity toward an integrated system for the detecting, locating, and destroying of landmines and unexploded ordinance using a laser to destroy landmines and unexploded ordinance and First Alliance’s Land Mine Locator (LML) system. The focus of this CRADA was on developing a sensor system that accurately detects landmines, and provides exact location information in a timely manner with extreme reliability.

Integrated planar terahertz resonators for femtomolar sensitivity label-free detection of DNA hybridization.

PubMed

Nagel, Michael; Bolivar, Peter Haring; Brucherseifer, Martin; Kurz, Heinrich; Bosserhoff, Anja; Büttner, Reinhard

2002-04-01

A promising label-free approach for the analysis of genetic material by means of detecting the hybridization of polynucleotides with electromagnetic waves at terahertz (THz) frequencies is presented. Using an integrated waveguide approach, incorporating resonant THz structures as sample carriers and transducers for the analysis of the DNA molecules, we achieve a sensitivity down to femtomolar levels. The approach is demonstrated with time-domain ultrafast techniques based on femtosecond laser pulses for generating and electro-optically detecting broadband THz signals, although the principle can certainly be transferred to other THz technologies.

Guided Wave Sensing In a Carbon Steel Pipe Using a Laser Vibrometer System

NASA Astrophysics Data System (ADS)

Ruíz Toledo, Abelardo; Salazar Soler, Jordi; Chávez Domínguez, Juan Antonio; García Hernández, Miguel Jesús; Turó Peroy, Antoni

2010-05-01

Non-Destructive Evaluation (NDE) techniques have achieved a great development during the last decades as a valuable tool for material characterization, manufacturing control and structural integrity tests. Among these tools, the guided wave technology has been rapidly extended because it reduces inspection time and costs compared to the ordinary point by point testing in large structures, as well as because of the possibility of inspecting under insulation and coating conditions. This fast development has motivated the creation of several inspection and material characterization systems including different technologies which can be combined with this technique. Different measurements systems based on laser techniques have been presented in order to inspect pipes, plates and diverse structures. Many of them are experimental systems of high cost and complexity which combine the employment of a laser for generation of waves in the structure and an interferometer for detection. Some of them employ air-coupled ultrasound generation transducers, with high losses in air and which demand high energy for exciting waves in materials of high stiffness. The combined employment of a commercial vibrometer system for Lamb wave sensing in plates has been successfully shown in the literature. In this paper we present a measurement system based on the combined employment of a piezoelectric wedge transducer and a laser vibrometer to sense guided acoustic waves in carbon steel pipes. The measurement system here presented is mainly compounded of an angular wedge transducer, employed to generate the guided wave and a commercial laser vibrometer used in the detection process. The wedge transducer is excited by means of a signal function generator whose output signal has been amplified with a power signal amplifier. A high precision positioning system is employed to place the laser beam at different points through the pipe surface. The signal detected by the laser vibrometer system is amplified with a signal amplifier and then it is displayed in a digital storage oscilloscope. This set-up offers the possibility of analyzing in a simpler way the wave propagation and the material evaluation in pipes of certain wall thickness. The material characterization considering distinct wave propagation modes can be easily achieved, changing the different incident angles of the wedge piezoelectric probe and their combined employment with several driving signals. Moreover, this experimental sensing system offers other possibilities of inspecting and analyzing the wave propagation in some features (bends, flange joints, welds,…) of the pipe surface which cause very large reflections and mode conversions and which in practice limits the inspection range when are inspected with conventional receiving transducer arrangements.

Research on the laser angle deception jamming technology of laser countermeasure

NASA Astrophysics Data System (ADS)

Ma, Shi-wei; Chen, Wen-jian; Gao, Wei; Duan, Yuan-yuan

2015-10-01

In recent years , laser guided weapons behave very well at destroying the military goals in the local wars, the single-shot probability, effective range and hitting precision getting better. And the semi-active laser guided weapons are the most widely used laser guided weapons. In order to improve the viability and protect important military goals, it's necessary to study the technology to against the semi-active guided weapons. This paper studies the working principle, the advantages and disadvantages of the semi-active guided weapons at first, and analyze the possibility of laser angle deception jamming system working. Then it analyzes the working principle and process of laser angle deception jamming technology. Finally it designs a half-real simulation system of laser angle deception jamming, which consists of semi-active laser guided weapons simulation system and laser angle deception jamming system. The simulation system demonstrates the working process of the laser angle deception jamming system. This paper provides fundamental base for the research on the countermeasure technology of semi-active laser guided weapons.

Research on key technology of space laser communication network

NASA Astrophysics Data System (ADS)

Chang, Chengwu; Huang, Huiming; Liu, Hongyang; Gao, Shenghua; Cheng, Liyu

2016-10-01

Since the 21st century, Spatial laser communication has made a breakthrough development. Europe, the United States, Japan and other space powers have carried out the test of spatial laser communication technology on-orbit, and put forward a series of plans. In 2011, China made the first technology demonstration of satellite-ground laser communication carried by HY-2 satellite. Nowadays, in order to improve the transmission rate of spatial network, the topic of spatial laser communication network is becoming a research hotspot at home and abroad. This thesis, from the basic problem of spatial laser communication network to solve, analyzes the main difference between spatial network and ground network, which draws forth the key technology of spatial laser communication backbone network, and systematically introduces our research on aggregation, addressing, architecture of spatial network. From the perspective of technology development status and trends, the thesis proposes the development route of spatial laser communication network in stages. So as to provide reference about the development of spatial laser communication network in China.

Rapid detection and differentiation of Staphylococcus colonies using an optical scattering technology.

PubMed

Alsulami, Tawfiq S; Zhu, Xingyue; Abdelhaseib, Maha Usama; Singh, Atul K; Bhunia, Arun K

2018-05-24

Staphylococcus species are a major pathogen responsible for nosocomial infections and foodborne illnesses. We applied a laser-based BARDOT (bacterial rapid detection using optical scattering technology) for rapid colony screening and detection of Staphylococcus on an agar plate and differentiate these from non-Staphylococcus spp. Among the six growth media tested, phenol red mannitol agar (PRMA) was found most suitable for building the Staphylococcus species scatter image libraries. Scatter image library for Staphylococcus species gave a high positive predictive value (PPV 87.5-100%) when tested against known laboratory strains of Staphylococcus spp., while the PPV against non-Staphylococcus spp. was 0-38%. A total of nine naturally contaminated bovine raw milk and ready-to-eat chicken salad samples were tested, and BARDOT detected Staphylococcus including Staphylococcus aureus with 80-100% PPV. Forty-five BARDOT-identified bacterial isolates from naturally contaminated foods were further confirmed by tuf and nuc gene-specific PCR and 16S rRNA gene sequence. This label-free, non-invasive on-plate colony screening technology can be adopted by the food industries, biotechnology companies, and public health laboratories for Staphylococcus species detection including S. aureus from various samples for food safety and public health management. Graphical abstract.

Coherent dual-frequency lidar system design for distance and speed measurements

NASA Astrophysics Data System (ADS)

Zheng, Xingyuan; Zhao, Changming; Zhang, Haiyang; Zheng, Zheng; Yang, Hongzhi

2018-01-01

Lidars have a wide range of applications in military detection and civilian remote sensing. Coherent Dual-Frequency Lidar (CDFL) is a new concept of laser radar that is using electrical coherence instead of optical coherence. It uses laser with two coherent frequency components as transmitting wave. The method is based on the use of an optically-carried radio frequency (RF) signal, which is the frequency difference between the two components, which is specially designed for distance and speed measurements. It not only ensures the system has the characteristics of high spatial resolution, high ranging and velocity precision of laser radar, but also can use mature signal processing technology of microwave radar, and it is a research direction that attracts more concern in recent years. A CDFL detection system is constructed and field experiment is carried out. In the system, a narrow linewidth fiber laser with a wavelength of 1064nm is adopted. The dual-frequency laser with frequency difference of 200MHz and 200.6MHz is obtained by acousto-optic frequency shift and recombination. The maximum output power of dual frequency laser is 200mW. The receiver consists of all-fiber balanced InGaAs photo-detector and homemade analog signal processing board. The experimental results show that the distance resolution and velocity resolution of the system are 0.1m and 0.1m/s separately when the working distance is greater than 200m, and the spatial resolution is 0.5mrad.

[From Einstein's Quantum Theory to modern laser therapy. The history of lasers in dermatology and aesthetic medicine].

PubMed

Graudenz, K; Raulin, C

2003-07-01

Laser technology has considerably expanded therapeutic modalities in dermatology and aesthetic medicine. In addition, lasers have broadened the spectrum of diagnostic and therapeutic options in many other medical fields. Dermatologists, especially Dr. Leon Goldman, played an important role in the evolution and use of medical lasers. There was a long way from the concept of stimulated emission as the fundamental idea of laser technology by Albert Einstein in 1917 to the practical use of the laser today. We review the development of laser technology from the early days through the latest advances.

Flight Testing of the TWiLiTE Airborne Molecular Doppler Lidar

NASA Technical Reports Server (NTRS)

Gentry, Bruce; McGill, Matthew; Machan, Roman; Reed, Daniel; Cargo, Ryan; Wilkens, David J.; Hart, William; Yorks, John; Scott, Stan; Wake, Shane;

Application of Laser Based Ultrasound for NDE of Damage in Thick Stitched Composites

NASA Technical Reports Server (NTRS)

Anastasi, Robert F.; Friedman, Adam D.; Hinders, Mark K.; Madaras, Eric I.

1997-01-01

As design engineers implement new composite systems such as thick, load bearing composite structures, they must have certifiable confidence in structure s durability and worthiness. This confidence builds from understanding the structural response and failure characteristics of simple components loaded in testing machines to tests on full scale sections. Nondestructive evaluation is an important element which can provide quantitative information on the damage initiation, propagation, and final failure modes for the composite structural components. Although ultrasound is generally accepted as a test method, the use of conventional ultrasound for in-situ monitoring of damage during tests of large structures is not practical. The use of lasers to both generate and detect ultrasound extends the application of ultrasound to in- situ sensing of damage in a deformed structure remotely and in a non-contact manner. The goal of the present research is to utilize this technology to monitor damage progression during testing. The present paper describes the application of laser based ultrasound to quantify damage in thick stitched composite structural elements to demonstrate the method. This method involves using a Q-switched laser to generate a rapid, local linear thermal strain on the surface of the structure. This local strain causes the generation of ultrasonic waves into the material. A second laser used with a Fabry-Perot interferometer detects the surface deflections. The use of fiber optics provides for eye safety and a convenient method of delivering the laser over long distances to the specimens. The material for these structural elements is composed of several stacks of composite material assembled together by stitching through the laminate thickness that ranging from 0.5 to 0.8 inches. The specimens used for these nondestructive evaluation studies had either impact damage or skin/stiffener interlaminar failure. Although little or no visible surface damage existed, internal damage was detected by laser based ultrasound.

A simple laser locking system based on a field-programmable gate array.

PubMed

Jørgensen, N B; Birkmose, D; Trelborg, K; Wacker, L; Winter, N; Hilliard, A J; Bason, M G; Arlt, J J

2016-07-01

Frequency stabilization of laser light is crucial in both scientific and industrial applications. Technological developments now allow analog laser stabilization systems to be replaced with digital electronics such as field-programmable gate arrays, which have recently been utilized to develop such locking systems. We have developed a frequency stabilization system based on a field-programmable gate array, with emphasis on hardware simplicity, which offers a user-friendly alternative to commercial and previous home-built solutions. Frequency modulation, lock-in detection, and a proportional-integral-derivative controller are programmed on the field-programmable gate array and only minimal additional components are required to frequency stabilize a laser. The locking system is administered from a host-computer which provides comprehensive, long-distance control through a versatile interface. Various measurements were performed to characterize the system. The linewidth of the locked laser was measured to be 0.7 ± 0.1 MHz with a settling time of 10 ms. The system can thus fully match laser systems currently in use for atom trapping and cooling applications.

A simple laser locking system based on a field-programmable gate array

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

Jørgensen, N. B.; Birkmose, D.; Trelborg, K.

Frequency stabilization of laser light is crucial in both scientific and industrial applications. Technological developments now allow analog laser stabilization systems to be replaced with digital electronics such as field-programmable gate arrays, which have recently been utilized to develop such locking systems. We have developed a frequency stabilization system based on a field-programmable gate array, with emphasis on hardware simplicity, which offers a user-friendly alternative to commercial and previous home-built solutions. Frequency modulation, lock-in detection, and a proportional-integral-derivative controller are programmed on the field-programmable gate array and only minimal additional components are required to frequency stabilize a laser. The lockingmore » system is administered from a host-computer which provides comprehensive, long-distance control through a versatile interface. Various measurements were performed to characterize the system. The linewidth of the locked laser was measured to be 0.7 ± 0.1 MHz with a settling time of 10 ms. The system can thus fully match laser systems currently in use for atom trapping and cooling applications.« less

Quasi RT-CW operation of InGaAs/InGaAsP strained quantum well lasers

NASA Astrophysics Data System (ADS)

Chen, J. X.; Li, A. Z.; Chen, Y. Q.; Guo, F. M.; Lin, C.; Zhang, Y. G.; Qi, M.

2001-07-01

Lasers with emission wavelength of 1.8-2.1 μm offer many important applications to laser spectroscopy, eye-safe medical care and trace chemical detection. Strained InGaAs/InGaAsP structures on InP substrates have been reported as an alternative approach for the development of semiconductor laser diodes in the spectral range 1.8-2.1 μm due to the superior InP substrate quality and mature processing technology. In this paper we report the fabrication and performances of InGaAs/InGaAsP/InP strained quantum well lasers grown by gas source molecular beam epitaxy. The diodes show good I- V characteristics, and the typical turn-on voltage at room temperature is around 0.4-0.5 V. A threshold current of about 120 mA is achieved for a chip with 500 μm cavity length and 4.5 μm stripe width. The maximum output power with 10% duty cycle is 18 mW. The main peak of the laser spectrum is located at 1.84 μm.

Two Micron Laser Technology Advancements at NASA Langley Research Center

NASA Technical Reports Server (NTRS)

Singh, Upendra N.

2010-01-01

An Independent Laser Review Panel set up to examine NASA s space-based lidar missions and the technology readiness of lasers appropriate for space-based lidars indicated a critical need for an integrated research and development strategy to move laser transmitter technology from low technical readiness levels to the higher levels required for space missions. Based on the review, a multiyear Laser Risk Reduction Program (LRRP) was initiated by NASA in 2002 to develop technologies that ensure the successful development of the broad range of lidar missions envisioned by NASA. This presentation will provide an overview of the development of pulsed 2-micron solid-state laser technologies at NASA Langley Research Center for enabling space-based measurement of wind and carbon dioxide.

Source technology as the foundation for modern infra-red counter measures (IRCM)

NASA Astrophysics Data System (ADS)

Grasso, Robert J.

2010-10-01

Protection of military aircraft from IR guided threats is paramount to ensure the survivability of aircrews, platforms, and to ensure mission success. At the foundation of all IRCM systems is the source; that component that provides the in-band radiant energy required for threat defeat. As such, source technology has evolved with IRCM technology to encompass the evolving systems architectures that encompass IRCM: 1) "Hot Brick" omni-directional sources; 2) arc lamps, and; 3) lasers. Lasers, as IRCM sources continue to evolve to meet the challenges of ever-evolving threats, superior techniques, economy of installation, and superior source technology. Lasers represent the single greatest advance in IRCM source technology and continue to evolve to meet ever more sophisticated threats. And have been used with great effect in all modern IRCM systems; evolving from frequency doubled CO2 lasers, to solid state lasers with OPOs, to semiconductor lasers including Quantum Cascade Lasers (QCLs); these last devices represent the latest advance in IRCM source technology offering all-band coverage, architectural simplicity, and economy of scale. While QCLs represent the latest advance in IRCM laser technology, fiber lasers show much promise in addressing multi-band operation as well as the ability to be coherently combined to achieve even greater output capability. Also, ultra-short pulse lasers are evolving to become practical for IRCM applications. Stay tuned ......

Possibilities of Laser Processing of Paper Materials

NASA Astrophysics Data System (ADS)

Stepanov, Alexander; Saukkonen, Esa; Piili, Heidi

Nowadays, lasers are applied in many industrial processes: the most developed technologies include such processes as laser welding, hybrid welding, laser cutting of steel, etc. In addition to laser processing of metallic materials, there are also many industrial applications of laser processing of non-metallic materials, like laser welding of polymers, laser marking of glass and laser cutting of wood-based materials. It is commonly known that laser beam is suitable for cutting of paper materials as well as all natural wood-fiber based materials. This study reveals the potential and gives overview of laser application in processing of paper materials. In 1990's laser technology increased its volume in papermaking industry; lasers at paper industry gained acceptance for different perforating and scoring applications. Nowadays, with reduction in the cost of equipment and development of laser technology (especially development of CO2 technology), laser processing of paper material has started to become more widely used and more efficient. However, there exists quite little published research results and reviews about laser processing of paper materials. In addition, forest industry products with pulp and paper products in particular are among major contributors for the Finnish economy with 20% share of total exports in the year 2013. This has been the standpoint of view and motivation for writing this literature review article: when there exists more published research work, knowledge of laser technology can be increased to apply it for processing of paper materials.

Application of tunable diode laser absorption spectroscopy in the detection of oxygen

NASA Astrophysics Data System (ADS)

Zhou, Xin; Jin, Xing

2015-10-01

Most aircrafts is driven by chemic energy which is released in the combustion process. For improving the capability of engine and controlling the running on-time, the processes of fuel physics and chemistry need to be analysis by kinds of high quality sensor. In the research of designing and improving the processes of fuel physics and chemistry, the concentration, temperature and velocity of kinds of gas in the combustor need to be detected and measured. In addition, these engines and research equipments are always in the harsh environment of high temperature, high pressure and high speed. The harsh environment needs the sensor to be high reliability, well repetition, no cross- sensitivity between gases, and the traditional measurement system can't satisfy the metrical requirement well. Tunable diode laser absorption spectroscopy (TDLAS) analytic measurement technology can well satisfy the measurement in the harsh environment, which can support the whole measurement plan and high quality measurement system. Because the TDLAS sensor has the excellence of small bulk, light weight, high reliability and well specifically measurement, the TDLAS measurement technology has wide prospects. Different from most measurements, only a beam of laser can be pass through the measured environment by TDLAS, and the measurement equipment needn't be set in the harsh environment. So, the TDLAS equipment can't be interrupted by the measured equipment. The ability of subsistence in the harsh environment is very valuable, especially in the measurement on the subject of aerospace with environment of high speed, combustion and plasma. This paper focuses on the collecting the articles on the subject of oxygen detection of TDLAS. By analyzing the research and results of the articles, we conclude the central issues, difficulties and results. And we can get some instructive conclusions.

Infrared light sensor applied to early detection of tooth decay

NASA Astrophysics Data System (ADS)

Benjumea, Eberto; Espitia, José; Díaz, Leonardo; Torres, Cesar

2017-08-01

The approach dentistry to dental care is gradually shifting to a model focused on early detection and oral-disease prevention; one of the most important methods of prevention of tooth decay is opportune diagnosis of decay and reconstruction. The present study aimed to introduce a procedure for early diagnosis of tooth decay and to compare result of experiment of this method with other common treatments. In this setup, a laser emitting infrared light is injected in core of one bifurcated fiber-optic and conduced to tooth surface and with the same bifurcated fiber the radiation reflected for the same tooth is collected and them conduced to surface of sensor that measures thermal and light frequencies to detect early signs of decay below a tooth surface, where demineralization is difficult to spot with x-ray technology. This device will can be used to diagnose tooth decay without any chemicals and rays such as high power lasers or X-rays.

A coal mine multi-point fiber ethylene gas concentration sensor

NASA Astrophysics Data System (ADS)

Wei, Yubin; Chang, Jun; Lian, Jie; Liu, Tongyu

2015-03-01

Spontaneous combustion of the coal mine goaf is one of the main disasters in the coal mine. The detection technology based on symbolic gas is the main means to realize the spontaneous combustion prediction of the coal mine goaf, and ethylene gas is an important symbol gas of spontaneous combustion in the coal accelerated oxidation stage. In order to overcome the problem of current coal ethylene detection, the paper presents a mine optical fiber multi-point ethylene concentration sensor based on the tunable diode laser absorption spectroscopy. Based on the experiments and analysis of the near-infrared spectrum of ethylene, the system employed the 1.62 μm (DFB) wavelength fiber coupled distributed feedback laser as the light source. By using the wavelength scanning technique and developing a stable fiber coupled Herriot type long path gas absorption cell, a ppm-level high sensitivity detecting system for the concentration of ethylene gas was realized, which could meet the needs of coal mine fire prevention goaf prediction.

Development of an EMCCD for LIDAR applications

NASA Astrophysics Data System (ADS)

De Monte, B.; Bell, R. T.

2017-11-01

A novel detector, incorporating e2v's EMCCD (L3VisionTM) [1] technology for use in LIDAR (Light Detection And Ranging) applications has been designed, manufactured and characterised. The most critical performance aspect was the requirement to collect charge from a 120μm square detection area for a 667ns temporal sampling window, with low crosstalk between successive samples, followed by signal readout with sub-electron effective noise. Additional requirements included low dark signal, high quantum efficiency at the 355nm laser wavelength and the ability to handle bright laser echoes, without corruption of the much fainter useful signals. The detector architecture used high speed charge binning to combine signal from each sampling window into a single charge packet. This was then passed through a multiplication register (EMCCD) operating with a typical gain of 100X to a conventional charge detection circuit. The detector achieved a typical quantum efficiency of 80% and a total noise in darkness of < 0.5 electrons rms. Development of the detector was supported by ESA.

External cavity tunable quantum cascade lasers and their applications to trace gas monitoring.

PubMed

Rao, Gottipaty N; Karpf, Andreas

2011-02-01

Since the first quantum cascade laser (QCL) was demonstrated approximately 16 years ago, we have witnessed an explosion of interesting developments in QCL technology and QCL-based trace gas sensors. QCLs operate in the mid-IR region (3-24 μm) and can directly access the rotational vibrational bands of most molecular species and, therefore, are ideally suited for trace gas detection with high specificity and sensitivity. These sensors have applications in a wide range of fields, including environmental monitoring, atmospheric chemistry, medical diagnostics, homeland security, detection of explosive compounds, and industrial process control, to name a few. Tunable external cavity (EC)-QCLs in particular offer narrow linewidths, wide ranges of tunability, and stable power outputs, which open up new possibilities for sensor development. These features allow for the simultaneous detection of multiple species and the study of large molecules, free radicals, ions, and reaction kinetics. In this article, we review the current status of EC-QCLs and sensor developments based on them and speculate on possible future developments.

Generating the Local Oscillator "Locally" in Continuous-Variable Quantum Key Distribution Based on Coherent Detection

NASA Astrophysics Data System (ADS)

Qi, Bing; Lougovski, Pavel; Pooser, Raphael; Grice, Warren; Bobrek, Miljko

2015-10-01

Continuous-variable quantum key distribution (CV-QKD) protocols based on coherent detection have been studied extensively in both theory and experiment. In all the existing implementations of CV-QKD, both the quantum signal and the local oscillator (LO) are generated from the same laser and propagate through the insecure quantum channel. This arrangement may open security loopholes and limit the potential applications of CV-QKD. In this paper, we propose and demonstrate a pilot-aided feedforward data recovery scheme that enables reliable coherent detection using a "locally" generated LO. Using two independent commercial laser sources and a spool of 25-km optical fiber, we construct a coherent communication system. The variance of the phase noise introduced by the proposed scheme is measured to be 0.04 (rad2 ), which is small enough to enable secure key distribution. This technology also opens the door for other quantum communication protocols, such as the recently proposed measurement-device-independent CV-QKD, where independent light sources are employed by different users.

Bubble-on-fiber (BoF): a built-in tunable broadband acousto-optic sensor for liquid-immersible in situ measurements.

PubMed

Xu, Hongsong; Wang, Guanyu; Ma, Jun; Jin, Long; Oh, Kyunghwan; Guan, Bai-Ou

2018-04-30

A new type of tunable broadband fiber-optic acousto-optic sensor was experimentally demonstrated by utilizing a bubble-on-fiber (BoF) interferometer. A single micro-bubble was generated by injecting a heating laser at λ = 980 nm on the metalized facet of an optical fiber. The BoF formed a spherical micro-cavity in water whose acoustic deformation was precisely detected by using a narrowband DFB laser at 1550 nm. The heating light and the interrogating light were fed into a single fiber probe by wavelength division multiplexing (WDM) realizing a small footprint all-fiber configuration. The diameter of the BoF was stabilized with a variation less than 0.5 nm by fast servo-control of the heating laser power. The stabilized BoF served as a Fabry-Pérot cavity that can be deformed by acoustic perturbation, and a minimum detectable pressure level of as low as ~1 mPa/Hz 1/2 was achieved in a frequency range of over 60 kHz in water at room temperature. Our proposed BoF technology can provide a tunable, flexible and all-fiber solution to detect minute acoustically driven perturbations combining high-precision interferometry. Due to the very small form-factor, the technique can find applications of liquid-immersible in situ measurements in bio-molecular/cell detection and biochemical phenomena study.

Analysis of exhaled breath by laser detection

NASA Astrophysics Data System (ADS)

Thrall, Karla D.; Toth, James J.; Sharpe, Steven W.

1996-04-01

The goal of our work is two fold: (1) to develop a portable rapid laser based breath analyzer for monitoring metabolic processes, and (2) predict these metabolic processes through physiologically based pharmacokinetic (PBPK) modeling. Small infrared active molecules such as ammonia, carbon monoxide, carbon dioxide, methane and ethane are present in exhaled breath and can be readily detected by laser absorption spectroscopy. In addition, many of the stable isotopomers of these molecules can be accurately detected, making it possible to follow specific metabolic processes. Potential areas of applications for this technology include the diagnosis of certain pathologies (e.g. Helicobacter Pylori infection), detection of trauma due to either physical or chemical causes and monitoring nutrient uptake (i.e., malnutrition). In order to understand the origin and elucidate the metabolic processes associated with these small molecules, we are employing physiologically based pharmacokinetic (PBPK) models. A PBPK model is founded on known physiological processes (i.e., blood flow rates, tissue volumes, breathing rate, etc.), chemical-specific processes (i.e., tissue solubility coefficients, molecular weight, chemical density, etc.), and on metabolic processes (tissue site and rate of metabolic biotransformation). Since many of these processes are well understood, a PBPK model can be developed and validated against the more readily available experimental animal data, and then by extrapolating the parameters to apply to man, the model can predict chemical behavior in humans.

Compact, High Energy 2-micron Coherent Doppler Wind Lidar Development for NASA's Future 3-D Winds Measurement from Space

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Koch, Grady; Yu, Jirong; Petros, Mulugeta; Beyon, Jeffrey; Kavaya, Michael J.; Trieu, Bo; Chen, Songsheng; Bai, Yingxin; Petzar, paul;

QCL as a game changer in MWIR and LWIR military and homeland security applications

NASA Astrophysics Data System (ADS)

Patel, C. Kumar N.; Lyakh, Arkadiy; Maulini, Richard; Tsekoun, Alexei; Tadjikov, Boris

2012-06-01

QCLs represent an important advance in MWIR and LWIR laser technology. With the demonstration of CW/RT QCLs, large number applications for QCLs have opened up, some of which represent replacement of currently used laser sources such as OPOs and OPSELs, and others being new uses which were not possible using earlier MWIR/LWIR laser sources, namely OPOs, OPSELs and CO2 lasers. Pranalytica has made significant advances in CW/RT power and WPE of QCLs and through its invention of a new QCL structure design, the non-resonant extraction, has demonstrated single emitter power of >4.7 W and WPE of >17% in the 4.4μm-5.0μm region. Pranalytica has also been commercially supplying the highest power MWIR QCLs with high WPEs. The NRE design concept now has been extended to the shorter wavelengths (3.8μm-4.2μm) with multiwatt power outputs and to longer wavelengths (7μm-10μm) with >1 W output powers. The high WPE of the QCLs permits RT operation of QCLs without using TECs in quasi-CW mode where multiwatt average powers are obtained even in ambient T>70°C. The QCW uncooled operation is particularly attractive for handheld, battery-operated applications where electrical power is limited. This paper describes the advances in QCL technology and applications of the high power MWIR and LWIR QCLs for defense applications, including protection of aircraft from MANPADS, standoff detection of IEDs, insitu detection of CWAs and explosives, infrared IFF beacons and target designators. We see that the SWaP advantages of QCLs are game changers.

Miniaturized pulsed laser source for time-domain diffuse optics routes to wearable devices.

PubMed

Di Sieno, Laura; Nissinen, Jan; Hallman, Lauri; Martinenghi, Edoardo; Contini, Davide; Pifferi, Antonio; Kostamovaara, Juha; Mora, Alberto Dalla

2017-08-01

We validate a miniaturized pulsed laser source for use in time-domain (TD) diffuse optics, following rigorous and shared protocols for performance assessment of this class of devices. This compact source (12×6  mm2) has been previously developed for range finding applications and is able to provide short, high energy (∼100  ps, ∼0.5  nJ) optical pulses at up to 1 MHz repetition rate. Here, we start with a basic level laser characterization with an analysis of suitability of this laser for the diffuse optics application. Then, we present a TD optical system using this source and its performances in both recovering optical properties of tissue-mimicking homogeneous phantoms and in detecting localized absorption perturbations. Finally, as a proof of concept of in vivo application, we demonstrate that the system is able to detect hemodynamic changes occurring in the arm of healthy volunteers during a venous occlusion. Squeezing the laser source in a small footprint removes a key technological bottleneck that has hampered so far the realization of a miniaturized TD diffuse optics system, able to compete with already assessed continuous-wave devices in terms of size and cost, but with wider performance potentialities, as demonstrated by research over the last two decades. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Combining Frequency Doubling Technology Perimetry and Scanning Laser Polarimetry for Glaucoma Detection

PubMed Central

Mwanza, Jean-Claude; Warren, Joshua L.; Hochberg, Jessica T.; Budenz, Donald L.; Chang, Robert T.; Ramulu, Pradeep Y.

2014-01-01

Purpose To determine the ability of frequency doubling technology (FDT) and scanning laser polarimetry with variable corneal compensation (GDx-VCC) to detect glaucoma when used individually and in combination. Methods One hundred and ten normal and 114 glaucomatous subjects were tested with FDT C-20-5 screening protocol and the GDx-VCC. The discriminating ability was tested for each device individually and for both devices combined using GDx-NFI, GDx-TSNIT, number of missed points of FDT, and normal or abnormal FDT. Measures of discrimination included sensitivity, specificity, area under the curve (AUC), Akaike’s information criterion (AIC), and prediction confidence interval lengths (PIL). Results For detecting glaucoma regardless of severity, the multivariable model resulting from the combination of GDX-TSNIT, number of abnormal points on FDT (NAP-FDT), and the interaction GDx-TSNIT * NAP-FDT (AIC: 88.28, AUC: 0.959, sensitivity: 94.6%, specificity: 89.5%) outperformed the best single variable model provided by GDx-NFI (AIC: 120.88, AUC: 0.914, sensitivity: 87.8%, specificity: 84.2%). The multivariable model combining GDx-TSNIT, NAPFDT, and interaction GDx-TSNIT*NAP-FDT consistently provided better discriminating abilities for detecting early, moderate and severe glaucoma than the best single variable models. Conclusions The multivariable model including GDx-TSNIT, NAP-FDT, and the interaction GDX-TSNIT * NAP-FDT provides the best glaucoma prediction compared to all other multivariable and univariable models. Combining the FDT C-20-5 screening protocol and GDx-VCC improves glaucoma detection compared to using GDx or FDT alone. PMID:24777046

From Dye Laser Factory to Portable Semiconductor Laser: Four Generations of Sodium Guide Star Lasers for Adaptive Optics in Astronomy and Space Situational Awareness

NASA Astrophysics Data System (ADS)

d'Orgeville, C.; Fetzer, G.

This presentation recalls the history of sodium guide star laser systems used in astronomy and space situational awareness adaptive optics, analysing the impact that sodium laser technology evolution has had on routine telescope operations. While it would not be practical to describe every single sodium guide star laser system developed to date, it is possible to characterize their evolution in broad technology terms. The first generation of sodium lasers used dye laser technology to create the first sodium laser guide stars in Hawaii, California, and Spain in the late 1980's and 1990's. These experimental systems were turned into the first laser guide star facilities to equip medium-to-large diameter adaptive optics telescopes, opening a new era of LGS AO-enabled diffraction-limited imaging from the ground. Although they produced exciting scientific results, these laser guide star facilities were large, power-hungry and messy. In the USA, a second-generation of sodium lasers was developed in the 2000's that used cleaner, yet still large and complex, solid-state laser technology. These are the systems in routine operation at the 8-10m class astronomical telescopes and 4m-class satellite imaging facilities today. Meanwhile in Europe, a third generation of sodium lasers was being developed using inherently compact and efficient fiber laser technology, and resulting in the only commercially available sodium guide star laser system to date. Fiber-based sodium lasers will be deployed at two astronomical telescopes and at least one space debris tracking station this year. Although highly promising, these systems remain significantly expensive and they have yet to demonstrate high performance in the field. We are proposing to develop a fourth generation of sodium lasers: based on semiconductor technology, these lasers could provide the final solution to the problem of sodium laser guide star adaptive optics for all astronomy and space situational awareness applications.

Coherent Detection of High-Rate Optical PPM Signals

NASA Technical Reports Server (NTRS)

Vilnrotter, Victor; Fernandez, Michela Munoz

2006-01-01

A method of coherent detection of high-rate pulse-position modulation (PPM) on a received laser beam has been conceived as a means of reducing the deleterious effects of noise and atmospheric turbulence in free-space optical communication using focal-plane detector array technologies. In comparison with a receiver based on direct detection of the intensity modulation of a PPM signal, a receiver based on the present method of coherent detection performs well at much higher background levels. In principle, the coherent-detection receiver can exhibit quantum-limited performance despite atmospheric turbulence. The key components of such a receiver include standard receiver optics, a laser that serves as a local oscillator, a focal-plane array of photodetectors, and a signal-processing and data-acquisition assembly needed to sample the focal-plane fields and reconstruct the pulsed signal prior to detection. The received PPM-modulated laser beam and the local-oscillator beam are focused onto the photodetector array, where they are mixed in the detection process. The two lasers are of the same or nearly the same frequency. If the two lasers are of different frequencies, then the coherent detection process is characterized as heterodyne and, using traditional heterodyne-detection terminology, the difference between the two laser frequencies is denoted the intermediate frequency (IF). If the two laser beams are of the same frequency and remain aligned in phase, then the coherent detection process is characterized as homodyne (essentially, heterodyne detection at zero IF). As a result of the inherent squaring operation of each photodetector, the output current includes an IF component that contains the signal modulation. The amplitude of the IF component is proportional to the product of the local-oscillator signal amplitude and the PPM signal amplitude. Hence, by using a sufficiently strong local-oscillator signal, one can make the PPM-modulated IF signal strong enough to overcome thermal noise in the receiver circuits: this is what makes it possible to achieve near-quantum-limited detection in the presence of strong background. Following quantum-limited coherent detection, the outputs of the individual photodetectors are automatically aligned in phase by use of one or more adaptive array compensation algorithms [e.g., the least-mean-square (LMS) algorithm]. Then the outputs are combined and the resulting signal is processed to extract the high-rate information, as though the PPM signal were received by a single photodetector. In a continuing series of experiments to test this method (see Fig. 1), the local oscillator has a wavelength of 1,064 nm, and another laser is used as a signal transmitter at a slightly different wavelength to establish an IF of about 6 MHz. There are 16 photodetectors in a 4 4 focal-plane array; the detector outputs are digitized at a sampling rate of 25 MHz, and the signals in digital form are combined by use of the LMS algorithm. Convergence of the adaptive combining algorithm in the presence of simulated atmospheric turbulence for optical PPM signals has already been demonstrated in the laboratory; the combined output is shown in Fig. 2(a), and Fig. 2(b) shows the behavior of the phase of the combining weights as a function of time (or samples). We observe that the phase of the weights has a sawtooth shape due to the continuously changing phase in the down-converted output, which is not exactly at zero frequency. Detailed performance analysis of this coherent free-space optical communication system in the presence of simulated atmospheric turbulence is currently under way.

Laser diagnostic technology for early detection of pathogen infestation in orange fruits

NASA Astrophysics Data System (ADS)

Giubileo, Gianfranco; Lai, Antonella; Piccinelli, Delinda; Puiu, Adriana

2010-11-01

Due to an increased expectation of food products that respect high quality and safety standards, there is a need for the growth of accurate, fast, objective and non-destructive technologies for quality determination of food and agricultural products. For this purpose, a diagnostic system based on laser photoacoustic spectroscopy (LPAS) was developed at ENEA Frascati Molecular Spectroscopy Laboratory (Italy). In the design of the photoacoustic detector, particular emphasis was placed in attaining a high sensitivity in detecting ethylene (ET) down to sub-parts per billion level (minimum detectable concentration 0.2 ppb). This was required due to the necessity to monitor and follow up ET production at a single fruit scale. ET is normally synthesised in very low amounts by healthy citrus fruits; however stress conditions such as pathogen attack may induce a substantial increase in the synthesised ET. In the present paper, the comparison between the ET emitted by healthy oranges ( Citrus sinensis L. Osbeck) cv Navel and by Phytophthora citrophthora infested Navel orange fruits are reported. The obtained results show a well evident increase in ET emission from the infested fruit with respect to the healthy one, even 24 h after the inoculation with the pathogen; at that time the tissue necrosis was not yet visible, and the fruit was also not yet damaged. The possibility to perform a real time non-destructive detection of ET traces makes the LPAS a powerful tool for monitoring the healthy state of the citrus fruits.

Automated Lab-on-a-Chip Electrophoresis System

NASA Technical Reports Server (NTRS)

Willis, Peter A.; Mora, Maria; Greer, Harold F.; Fisher, Anita M.; Bryant, Sherrisse

2012-01-01

Capillary electrophoresis is an analytical technique that can be used to detect and quantify extremely small amounts of various biological molecules. In the search for biochemical traces of life on other planets, part of this search involves an examination of amino acids, which are the building blocks of life on Earth. The most sensitive method for detecting amino acids is the use of laser induced fluorescence. However, since amino acids do not, in general, fluoresce, they first must be reacted with a fluorescent dye label prior to analysis. After this process is completed, the liquid sample then must be transported into the electrophoresis system. If the system is to be reused multiple times, samples must be added and removed each time. In typical laboratories, this process is performed manually by skilled human operators using standard laboratory equipment. This level of human intervention is not possible if this technology is to be implemented on extraterrestrial targets. Microchip capillary electrophoresis (CE) combined with laser induced fluorescence detection (LIF) was selected as an extremely sensitive method to detect amino acids and other compounds that can be tagged with a fluorescent dye. It is highly desirable to package this technology into an integrated, autonomous, in situ instrument capable of performing CE-LIF on the surface of an extraterrestrial body. However, to be fully autonomous, the CE device must be able to perform a large number of sample preparation and analysis operations without the direct intervention of a human.

Study of UV imaging technology for noninvasive detection of latent fingerprints

NASA Astrophysics Data System (ADS)

Li, Hong-xia; Cao, Jing; Niu, Jie-qing; Huang, Yun-gang

2013-09-01

Using UV imaging technology, according to the special absorption 、reflection 、scattering and fluorescence characterization of the various residues in fingerprints (fatty acid ester, protein, and carboxylic acid salts etc) to the UV light, weaken or eliminate the background disturbance to increase the brightness contrast of fingerprints with the background, and design、setup the illumination optical system and UV imaging system, the noninvasive detection of latent fingerprints remaining on various object surface are studied. In the illumination optical system, using the 266nm UV Nd:YAG solid state laser as illumination light source, by calculating the best coupling conditions of the laser beam with UV liquid core fiber and analyzing the beam transforming characterizations, we designed and setup the optical system to realize the UV imaging uniform illumination. In the UV imaging system, the UV lens is selected as the fingerprint imaging element, and the UV intensified CCD (ICCD) which consists of a second-generation UV image intensifier and a CCD coupled by fiber plate and taper directly are used as the imaging sensing element. The best imaging conditions of the UV lens with ICCD were analyzed and the imaging system was designed and setup. In this study, by analyzing the factors which influence the detection effect, optimal design and setup the illumination system and imaging system, latent fingerprints on the surface of the paint tin box、plastic、smooth paper、notebook paper and print paper were noninvasive detected and appeared, and the result meet the fingerprint identification requirements in forensic science.

Mid-Infrared Trace Gas Sensor Technology Based on Intracavity Quartz-Enhanced Photoacoustic Spectroscopy

PubMed Central

Wojtas, Jacek; Gluszek, Aleksander; Hudzikowski, Arkadiusz; Tittel, Frank K.

2017-01-01

The application of compact inexpensive trace gas sensor technology to a mid-infrared nitric oxide (NO) detectoion using intracavity quartz-enhanced photoacoustic spectroscopy (I-QEPAS) is reported. A minimum detection limit of 4.8 ppbv within a 30 ms integration time was demonstrated by using a room-temperature, continuous-wave, distributed-feedback quantum cascade laser (QCL) emitting at 5.263 µm (1900.08 cm−1) and a new compact design of a high-finesse bow-tie optical cavity with an integrated resonant quartz tuning fork (QTF). The optimum configuration of the bow-tie cavity was simulated using custom software. Measurements were performed with a wavelength modulation scheme (WM) using a 2f detection procedure. PMID:28273836

Advances in lasers and optical micro-nano-systems

NASA Astrophysics Data System (ADS)

Laurell, F.; Fazio, E.

2010-09-01

Lasers represent a well consolidated technology: nevertheless, research in this field remains very active and productive, in both basic and applied directions. At the moment significant attention is given to those sources that bring together high power and compactness. Such high power lasers find important applications for material treatments and such applications are presented by Ehsani et al and Saiedeh Saghafi et al, in the treatment of dielectric thin films (Alteration of optical and morphological properties of polycarbonate illuminated by visible/IR laser beams) or of biological tissues like pistachio seeds (Investigating the effects of laser beams (532 and 660 nm) in annihilation of pistachio mould fungus using spectrophotometry analysis). In particular the latter paper show how laser sources can find very important applications in new domains, preserving goods and food without the need for preservatives or pesticides by simply sterilizing them using light. Optical Micro and Nano Systems presents a new domain for exploration. In this framework this special issue is very attractive, because it assembles papers reporting new results in three directions: new techniques for monitoring integrated micro- and nano-systems, new integrated systems and novel high performance metamaterial configurations. Integrated micro-components can be monitored and controlled using reflectance measurements as presented by Piombini et al (Toward the reflectance measurement of micro components). Speckle formation during laser beam reflection can also be a very sophisticated tool for detecting ultra-precise displacements, as presented by Filter et al (High resolution displacement detection with speckles : accuracy limits in linear displacement speckle metrology). Three dimensional integrated optical structures is indeed a big challenge and a peculiarity of photonics, they can be formed through traditional holography or using more sophisticated and novel ! technologies. Thus, special manipulation of the writing-reading optical beam can push holography toward storages at higher data densities, as presented by Norihiko Ishii et al (Wavefront compensation method using novel index in holographic data storage). Along a similar direction Furlan et al describe a very innovative technique for producing optical traps using novel Devil micro-lenses (Volumetric multiple optical traps produced by Devil's lenses). Vynnyk et al presented an interesting application of electron microscopy for monitoring sub-micrometric structures in 3D configurations (3D-measurement with the stereo scanning electron microscope on sub-micrometer structure). Finally, S. Rao et al present two interesting papers on integrated structures compatible with silicon technology: one describes the realisation of low-loss waveguides using amorphous silicon, a relatively novel material with many applications in very different domains (Low-loss amorphous silicon waveguid! es grown by PECVD on indium tin oxide), and one on the realisation of a electrically drivable device with affective compatibility with CMOS technology (Electro-optical modulating multistack device based on the CMOS-compatible technology of amorphous silicon). We hope that this special issue of the Journal of the European Optical Society will reflect the interest of the European Scientific Community toward these fundamental and applied topics and will demonstrate to readers some of the actual directions of research. We express our full appreciation to the authors that participated to this initiative which acts only as a primer for the vast amount of work now being undertaken in laser physics and applications in micro- and nano-systems. We would like to give a special thank to the paper reviewers for their important role in the paper selection process and all the journal staff for their very professional support, dedication and energy, which made this special issue feasible.

Direct metal laser sintering: a digitised metal casting technology.

PubMed

Venkatesh, K Vijay; Nandini, V Vidyashree

2013-12-01

Dental technology is undergoing advancements at a fast pace and technology is being imported from various other fields. One such imported technology is direct metal laser sintering technology for casting metal crowns. This article will discuss the process of laser sintering for making metal crowns and fixed partial dentures with a understanding of their pros and cons.

The Use of Laser Microdissection in Forensic Sexual Assault Casework: Pros and Cons Compared to Standard Methods.

PubMed

Costa, Sergio; Correia-de-Sá, Paulo; Porto, Maria J; Cainé, Laura

2017-07-01

Sexual assault samples are among the most frequently analyzed in a forensic laboratory. These account for almost half of all samples processed routinely, and a large portion of these cases remain unsolved. These samples often pose problems to traditional analytic methods of identification because they consist most frequently of cell mixtures from at least two contributors: the victim (usually female) and the perpetrator (usually male). In this study, we propose the use of current preliminary testing for sperm detection in order to determine the chances of success when faced with samples which can be good candidates to undergo analysis with the laser microdissection technology. Also, we used laser microdissection technology to capture fluorescently stained cells of interest differentiated by gender. Collected materials were then used for DNA genotyping with commercially available amplification kits such as Minifiler, Identifiler Plus, NGM, and Y-Filer. Both the methodology and the quality of the results were evaluated to assess the pros and cons of laser microdissection compared with standard methods. Overall, the combination of fluorescent staining combined with the Minifiler amplification kit provided the best results for autosomal markers, whereas the Y-Filer kit returned the expected results regardless of the used method. © 2017 American Academy of Forensic Sciences.

Research on filling process of fuel and oxidant during detonation based on absorption spectrum technology

NASA Astrophysics Data System (ADS)

Lv, Xiao-Jing; Li, Ning; Weng, Chun-Sheng

2014-12-01

Research on detonation process is of great significance for the control optimization of pulse detonation engine. Based on absorption spectrum technology, the filling process of fresh fuel and oxidant during detonation is researched. As one of the most important products, H2O is selected as the target of detonation diagnosis. Fiber distributed detonation test system is designed to enable the detonation diagnosis under adverse conditions in detonation process. The test system is verified to be reliable. Laser signals at different working frequency (5Hz, 10Hz and 20Hz) are detected. Change of relative laser intensity in one detonation circle is analyzed. The duration of filling process is inferred from the change of laser intensity, which is about 100~110ms. The peak of absorption spectrum is used to present the concentration of H2O during the filling process of fresh fuel and oxidant. Absorption spectrum is calculated, and the change of absorption peak is analyzed. Duration of filling process calculated with absorption peak consisted with the result inferred from the change of relative laser intensity. The pulse detonation engine worked normally and obtained the maximum thrust at 10Hz under experiment conditions. The results are verified through H2O gas concentration monitoring during detonation.

Unreported Emission Lines of Rb, Ce, La, Sr, Y, Zr, Pb and Se Detected Using Laser-Induced Breakdown Spectroscopy

NASA Technical Reports Server (NTRS)

Lepore, K. H.; Mackie, J.; Dyar, M. D.; Fassett, C. I.

2017-01-01

Information on emission lines for major and minor elements is readily available from the National Institute of Standards and Technology (NIST) as part of the Atomic Spectra Database. However, tabulated emission lines are scarce for some minor elements and the wavelength ranges presented on the NIST database are limited to those included in existing studies. Previous work concerning minor element calibration curves measured using laser-induced break-down spectroscopy found evidence of Zn emission lines that were not documented on the NIST database. In this study, rock powders were doped with Rb, Ce, La, Sr, Y, Zr, Pb and Se in concentrations ranging from 10 percent to 10 parts per million. The difference between normalized spectra collected on samples containing 10 percent dopant and those containing only 10 parts per million were used to identify all emission lines that can be detected using LIBS (Laser-Induced Breakdown Spectroscopy) in a ChemCam-like configuration at the Mount Holyoke College LIBS facility. These emission spectra provide evidence of many previously undocumented emission lines for the elements measured here.

Cost-effective SU-8 micro-structures by DUV excimer laser lithography for label-free biosensing

NASA Astrophysics Data System (ADS)

Sanza, F. J.; Laguna, M. F.; Casquel, R.; Holgado, M.; Barrios, C. A.; Ortega, F. J.; López-Romero, D.; García-Ballesteros, J. J.; Bañuls, M. J.; Maquieira, A.; Puchades, R.

2011-04-01

Cost-effective SU-8 micro-structures on a silicon substrate were developed using 248 nm excimer laser KrF projection, studying the influence of the different variables on the final pattern geometry, finding out that the most critical are exposure dose and post-bake condition. Also a novel and cost effective type of photomask based on commercial polyimide Kapton produced by 355 nm DPSS laser microprocessing was developed, studying the influence of the cutting conditions on the photomask. Finally, as a likely application the biosensing capability with a standard BSA/antiBSA immunoassay over a 10 × 10 micro-plates square lattice of around 10 μm in diameter, 15 μm of spacing and 400 nm in height was demonstrated, finding a limit of detection (LOD) of 33.4 ng/ml which is in the order of magnitude of bioapplications such as detection of cortisol hormone or insulin-like growth factor. Low cost fabrication and vertical interrogation characterization techniques lead to a promising future in the biosensing technology field.

Mineralogy and astrobiology detection using laser remote sensing instrument.

PubMed

Abedin, M Nurul; Bradley, Arthur T; Sharma, Shiv K; Misra, Anupam K; Lucey, Paul G; McKay, Christopher P; Ismail, Syed; Sandford, Stephen P

2015-09-01

A multispectral instrument based on Raman, laser-induced fluorescence (LIF), laser-induced breakdown spectroscopy (LIBS), and a lidar system provides high-fidelity scientific investigations, scientific input, and science operation constraints in the context of planetary field campaigns with the Jupiter Europa Robotic Lander and Mars Sample Return mission opportunities. This instrument conducts scientific investigations analogous to investigations anticipated for missions to Mars and Jupiter's icy moons. This combined multispectral instrument is capable of performing Raman and fluorescence spectroscopy out to a >100  m target distance from the rover system and provides single-wavelength atmospheric profiling over long ranges (>20  km). In this article, we will reveal integrated remote Raman, LIF, and lidar technologies for use in robotic and lander-based planetary remote sensing applications. Discussions are focused on recently developed Raman, LIF, and lidar systems in addition to emphasizing surface water ice, surface and subsurface minerals, organics, biogenic, biomarker identification, atmospheric aerosols and clouds distributions, i.e., near-field atmospheric thin layers detection for next robotic-lander based instruments to measure all the above-mentioned parameters.

Laser-based absorption spectroscopy as a technique for rapid in-line analysis of respired gas concentrations of O2 and CO2

PubMed Central

Cummings, Beth; Hamilton, Michelle L.; Ciaffoni, Luca; Pragnell, Timothy R.; Peverall, Rob; Ritchie, Grant A. D.; Hancock, Gus

2011-01-01

The use of sidestream analyzers for respired gas analysis is almost universal. However, they are not ideal for measurements of respiratory gas exchange because the analyses are both temporally dissociated from measurements of respiratory flow and also not generally conducted under the same physical conditions. This study explores the possibility of constructing an all optical, fast response, in-line breath analyzer for oxygen and carbon dioxide. Using direct absorption spectroscopy with a diode laser operating at a wavelength near 2 μm, measurements of expired carbon dioxide concentrations were obtained with an absolute limit of detection of 0.04% at a time resolution of 10 ms. Simultaneously, cavity enhanced absorption spectroscopy at a wavelength near 760 nm was employed to obtain measurements of expired oxygen concentrations with an absolute limit of detection of 0.26% at a time resolution of 10 ms. We conclude that laser-based absorption spectroscopy is a promising technology for in-line analysis of respired carbon dioxide and oxygen concentrations. PMID:21512147

Laser-based absorption spectroscopy as a technique for rapid in-line analysis of respired gas concentrations of O2 and CO2.

PubMed

Cummings, Beth; Hamilton, Michelle L; Ciaffoni, Luca; Pragnell, Timothy R; Peverall, Rob; Ritchie, Grant A D; Hancock, Gus; Robbins, Peter A

2011-07-01

The use of sidestream analyzers for respired gas analysis is almost universal. However, they are not ideal for measurements of respiratory gas exchange because the analyses are both temporally dissociated from measurements of respiratory flow and also not generally conducted under the same physical conditions. This study explores the possibility of constructing an all optical, fast response, in-line breath analyzer for oxygen and carbon dioxide. Using direct absorption spectroscopy with a diode laser operating at a wavelength near 2 μm, measurements of expired carbon dioxide concentrations were obtained with an absolute limit of detection of 0.04% at a time resolution of 10 ms. Simultaneously, cavity enhanced absorption spectroscopy at a wavelength near 760 nm was employed to obtain measurements of expired oxygen concentrations with an absolute limit of detection of 0.26% at a time resolution of 10 ms. We conclude that laser-based absorption spectroscopy is a promising technology for in-line analysis of respired carbon dioxide and oxygen concentrations.

Laser spectroscopy: Assessment of research needs for laser technologies applied to advanced spectroscopic methods

NASA Astrophysics Data System (ADS)

Hurst, G. S.

1990-05-01

This report is organized as follows. Section 2 summarizes the current program of DOE's Office of Health and Environmental Research (OHER) and provides some remarks on how laser science and technology could beneficially impact most of the research programs. Section 3 provides a brief global perspective on laser technology and attempts to define important trends in the field. Similarly, Section 4 provides a global perspective on laser spectroscopy and addresses important trends. Thus, Section 5 focuses on the trends in laser technology and spectroscopy which could impact the OHER mission in significant ways and contains the basis for recommendations made in the executive summary. For those with limited familiarity with laser technology and laser spectroscopy, reference is made to Appendix 1 for a list of abbreviations and acronyms. Appendix 2 can serve a useful review or tutorial for those who are not deeply involved with laser spectroscopy. Even those familiar with laser spectroscopy and laser technology may find it useful to know precisely what the authors of this document mean by certain specialized terms and expressions. Finally, a note on the style of referencing may be appropriate. Whenever possible a book or review articles is referenced as the preferred citation. However, we frequently found it useful to reference a number of individual papers of recent origin or those which were not conveniently found in the review articles.

The Slope Imaging Multi-polarization Photon-counting Lidar: an Advanced Technology Airborne Laser Altimeter

NASA Astrophysics Data System (ADS)

Dabney, P.; Harding, D. J.; Huss, T.; Valett, S.; Yu, A. W.; Zheng, Y.

2009-12-01

The Slope Imaging Multi-polarization Photon-counting Lidar (SIMPL) is an airborne laser altimeter developed through the NASA Earth Science Technology Office Instrument Incubator Program with a focus on cryopshere remote sensing. The SIMPL instrument incorporates a variety of advanced technologies in order to demonstrate measurement approaches of potential benefit for improved airborne laser swath mapping and spaceflight laser altimeter missions. SIMPL incorporates beam splitting, single-photon ranging and polarimetry technologies at green and near-infrared wavelengths in order to achieve simultaneous sampling of surface elevation, slope, roughness and scattering properties, the latter used to differentiate surface types. The transmitter is a 1 nsec pulse width, 11 kHz, 1064 nm microchip laser, frequency doubled to 532 nm and split into four plane-polarized beams using birefringent calcite crystal in order to maintain co-alignment of the two colors. The 16 channel receiver splits the received energy for each beam into the two colors and each color is split into energy parallel and perpendicular to the transmit polarization plane thereby proving a measure of backscatter depolarization. The depolarization ratio is sensitive to the proportions of specular reflection and surface and volume scattering, and is a function of wavelength. The ratio can differentiate, for example, water, young translucent ice, older granular ice and snow. The solar background count rate is controlled by spatial filtering using a pinhole array and by spectral filtering using temperature-controlled narrow bandwidth filters. The receiver is fiber coupled to 16 Single Photon Counting Modules (SPCMs). To avoid range biases due to the long dead time of these detectors the probability of detection per laser fire on each channel is controlled to be below 30%, using mechanical irises and flight altitude. Event timers with 0.1 nsec resolution in combination the narrow transmit pulse yields single photon ranging precision of 8 cm. The high speed, high throughput data system is capable of recording 22 million time-tagged photon detection events per second. At typical aircraft flight speeds, each of the 16 channels acquires a single photon range every 5 to 15 cm along the four profiles providing a highly sampled measure of surface roughness. The nominal flight altitude is 5 km yielding 10 m spacing between the four beam profiles, providing a measure of surface slope at 10 m length scales. The altitude is currently constrained by the low signal level of the NIR cross-polarized channels. SIMPL’s measurement capabilities provide information about surface elevation, roughness, slope and type of value in characterizing ice sheet surfaces and sea ice, including their melt state. Capabilities will be illustrated using data acquired over Lake Erie ice cover in February, 2009.

Four generations of sodium guide star lasers for adaptive optics in astronomy and space situational awareness

NASA Astrophysics Data System (ADS)

d'Orgeville, Céline; Fetzer, Gregory J.

2016-07-01

This paper recalls the history of sodium guide star laser systems used in astronomy and space situational awareness adaptive optics, analyzing the impact that sodium laser technology evolution has had on routine telescope operations. While it would not be practical to describe every single sodium guide star laser system developed to date, it is possible to characterize their evolution in broad technology terms. The first generation of sodium lasers used dye laser technology to create the first sodium laser guide stars in Hawaii, California, and Spain in the late 1980s and 1990s. These experimental systems were turned into the first laser guide star facilities to equip mediumto- large diameter adaptive optics telescopes, opening a new era of Laser Guide Star Adaptive Optics (LGS AO)-enabled diffraction-limited imaging from the ground. Although they produced exciting scientific results, these laser guide star facilities were large, power-hungry and messy. In the USA, a second-generation of sodium lasers was developed in the 2000s that used cleaner, yet still large and complex, solid-state laser technology. These are the systems in routine operation at the 8 to 10m-class astronomical telescopes and 4m-class satellite imaging facilities today. Meanwhile in Europe, a third generation of sodium lasers was being developed using inherently compact and efficient fiber laser technology, and resulting in the only commercially available sodium guide star laser system to date. Fiber-based sodium lasers are being or will soon be deployed at three astronomical telescopes and two space surveillance stations. These highly promising systems are still relatively large to install on telescopes and they remain significantly expensive to procure and maintain. We are thus proposing to develop a fourth generation of sodium lasers: based on semiconductor technology, these lasers could provide a definitive solution to the problem of sodium LGS AO laser sources for all astronomy and space situational awareness applications.

Long distance high power optical laser fiber break detection and continuity monitoring systems and methods

DOEpatents

Rinzler, Charles C.; Gray, William C.; Faircloth, Brian O.; Zediker, Mark S.

2016-02-23

A monitoring and detection system for use on high power laser systems, long distance high power laser systems and tools for performing high power laser operations. In particular, the monitoring and detection systems provide break detection and continuity protection for performing high power laser operations on, and in, remote and difficult to access locations.

The trillion planet survey: an optical search for directed intelligence in M31

NASA Astrophysics Data System (ADS)

Stewart, Andrew; Lubin, Philip

2017-09-01

In realm of optical SETI, searches for pulsed laser signals have historically been preferred over those for continuous wave beacons. There are many valid reasons for this, namely the near elimination of false positives and simple experimental components. However, due to significant improvements in laser technologies and light-detection systems since the mid-20th century, as well as new data from the recent Kepler mission, continuous wave searches should no longer be ignored. In this paper we propose a search for continuous wave laser beacons from an intelligent civilization in the Andromeda galaxy. Using only a 0.8 meter telescope, a standard photometric system, and an image processing pipeline, we expect to be able to detect any CW laser signal directed at us from an extraterrestrial civilization in M31, as long as the civilization is operating at a wavelength we can "see" and has left the beacon on long enough for us to detect it here on Earth. The search target is M31 due to its high stellar density relative to our own Milky Way galaxy. Andromeda is home to at least one trillion stars, and thus at least one trillion planets. As a result, in surveying M31, we are surveying one trillion planets, and consequently one trillion possible locations of intelligent life. This is an unprecedented number of targets relative to other past SETI searches. We call this the TPS or Trillion Planet Survey.

Market Assessment of Forward-Looking Turbulence Sensing Systems

NASA Technical Reports Server (NTRS)

Kauffmann, Paul; Sousa-Poza, Andres

2001-01-01

In recognition of the importance of turbulence mitigation as a tool to improve aviation safety, NASA's Aviation Safety Program developed a Turbulence Detection and Mitigation Sub-element. The objective of this effort is to develop highly reliable turbulence detection technologies for commercial transport aircraft to sense dangerous turbulence with sufficient time warning so that defensive measures can be implemented and prevent passenger and crew injuries. Current research involves three forward sensing products to improve the cockpit awareness of possible turbulence hazards. X-band radar enhancements will improve the capabilities of current weather radar to detect turbulence associated with convective activity. LIDAR (Light Detection and Ranging) is a laser-based technology that is capable of detecting turbulence in clear air. Finally, a possible Radar-LIDAR hybrid sensor is envisioned to detect the full range of convective and clear air turbulence. To support decisions relating to the development of these three forward-looking turbulence sensor technologies, the objective of this study was defined as examination of cost and implementation metrics. Tasks performed included the identification of cost factors and certification issues, the development and application of an implementation model, and the development of cost budget/targets for installing the turbulence sensor and associated software devices into the commercial transport fleet.

Object-based analysis of multispectral airborne laser scanner data for land cover classification and map updating

NASA Astrophysics Data System (ADS)

Matikainen, Leena; Karila, Kirsi; Hyyppä, Juha; Litkey, Paula; Puttonen, Eetu; Ahokas, Eero

2017-06-01

During the last 20 years, airborne laser scanning (ALS), often combined with passive multispectral information from aerial images, has shown its high feasibility for automated mapping processes. The main benefits have been achieved in the mapping of elevated objects such as buildings and trees. Recently, the first multispectral airborne laser scanners have been launched, and active multispectral information is for the first time available for 3D ALS point clouds from a single sensor. This article discusses the potential of this new technology in map updating, especially in automated object-based land cover classification and change detection in a suburban area. For our study, Optech Titan multispectral ALS data over a suburban area in Finland were acquired. Results from an object-based random forests analysis suggest that the multispectral ALS data are very useful for land cover classification, considering both elevated classes and ground-level classes. The overall accuracy of the land cover classification results with six classes was 96% compared with validation points. The classes under study included building, tree, asphalt, gravel, rocky area and low vegetation. Compared to classification of single-channel data, the main improvements were achieved for ground-level classes. According to feature importance analyses, multispectral intensity features based on several channels were more useful than those based on one channel. Automatic change detection for buildings and roads was also demonstrated by utilising the new multispectral ALS data in combination with old map vectors. In change detection of buildings, an old digital surface model (DSM) based on single-channel ALS data was also used. Overall, our analyses suggest that the new data have high potential for further increasing the automation level in mapping. Unlike passive aerial imaging commonly used in mapping, the multispectral ALS technology is independent of external illumination conditions, and there are no shadows on intensity images produced from the data. These are significant advantages in developing automated classification and change detection procedures.

Fractional exhaled nitric oxide-measuring devices: technology update

PubMed Central

Maniscalco, Mauro; Vitale, Carolina; Vatrella, Alessandro; Molino, Antonio; Bianco, Andrea; Mazzarella, Gennaro

2016-01-01

The measurement of exhaled nitric oxide (NO) has been employed in the diagnosis of specific types of airway inflammation, guiding treatment monitoring by predicting and assessing response to anti-inflammatory therapy and monitoring for compliance and detecting relapse. Various techniques are currently used to analyze exhaled NO concentrations under a range of conditions for both health and disease. These include chemiluminescence and electrochemical sensor devices. The cost effectiveness and ability to achieve adequate flexibility in sensitivity and selectivity of NO measurement for these methods are evaluated alongside the potential for use of laser-based technology. This review explores the technologies involved in the measurement of exhaled NO. PMID:27382340

Simulation study of melanoma detection in human skin tissues by laser-generated surface acoustic waves

NASA Astrophysics Data System (ADS)

Chen, Kun; Fu, Xing; Dorantes-Gonzalez, Dante J.; Lu, Zimo; Li, Tingting; Li, Yanning; Wu, Sen; Hu, Xiaotang

2014-07-01

Air pollution has been correlated to an increasing number of cases of human skin diseases in recent years. However, the investigation of human skin tissues has received only limited attention, to the point that there are not yet satisfactory modern detection technologies to accurately, noninvasively, and rapidly diagnose human skin at epidermis and dermis levels. In order to detect and analyze severe skin diseases such as melanoma, a finite element method (FEM) simulation study of the application of the laser-generated surface acoustic wave (LSAW) technique is developed. A three-layer human skin model is built, where LSAW's are generated and propagated, and their effects in the skin medium with melanoma are analyzed. Frequency domain analysis is used as a main tool to investigate such issues as minimum detectable size of melanoma, filtering spectra from noise and from computational irregularities, as well as on how the FEM model meshing size and computational capabilities influence the accuracy of the results. Based on the aforementioned aspects, the analysis of the signals under the scrutiny of the phase velocity dispersion curve is verified to be a reliable, a sensitive, and a promising approach for detecting and characterizing melanoma in human skin.

Simulation study of melanoma detection in human skin tissues by laser-generated surface acoustic waves.

PubMed

Chen, Kun; Fu, Xing; Dorantes-Gonzalez, Dante J; Lu, Zimo; Li, Tingting; Li, Yanning; Wu, Sen; Hu, Xiaotang

2014-01-01

Air pollution has been correlated to an increasing number of cases of human skin diseases in recent years. However, the investigation of human skin tissues has received only limited attention, to the point that there are not yet satisfactory modern detection technologies to accurately, noninvasively, and rapidly diagnose human skin at epidermis and dermis levels. In order to detect and analyze severe skin diseases such as melanoma, a finite element method (FEM) simulation study of the application of the laser-generated surface acoustic wave (LSAW) technique is developed. A three-layer human skin model is built, where LSAW’s are generated and propagated, and their effects in the skin medium with melanoma are analyzed. Frequency domain analysis is used as a main tool to investigate such issues as minimum detectable size of melanoma, filtering spectra from noise and from computational irregularities, as well as on how the FEM model meshing size and computational capabilities influence the accuracy of the results. Based on the aforementioned aspects, the analysis of the signals under the scrutiny of the phase velocity dispersion curve is verified to be a reliable, a sensitive, and a promising approach for detecting and characterizing melanoma in human skin.

Imaging live humans through smoke and flames using far-infrared digital holography.

PubMed

Locatelli, M; Pugliese, E; Paturzo, M; Bianco, V; Finizio, A; Pelagotti, A; Poggi, P; Miccio, L; Meucci, R; Ferraro, P

2013-03-11

The ability to see behind flames is a key challenge for the industrial field and particularly for the safety field. Development of new technologies to detect live people through smoke and flames in fire scenes is an extremely desirable goal since it can save human lives. The latest technologies, including equipment adopted by fire departments, use infrared bolometers for infrared digital cameras that allow users to see through smoke. However, such detectors are blinded by flame-emitted radiation. Here we show a completely different approach that makes use of lensless digital holography technology in the infrared range for successful imaging through smoke and flames. Notably, we demonstrate that digital holography with a cw laser allows the recording of dynamic human-size targets. In this work, easy detection of live, moving people is achieved through both smoke and flames, thus demonstrating the capability of digital holography at 10.6 μm.

Simulation of the Performances of WIND, an Airborne CO2 Lidar

NASA Technical Reports Server (NTRS)

Oh, D.; Dabas, A.; Lieutaud, F.; Loth, C.; Flamant, P. H.

1992-01-01

An airborne Doppler coherent lidar is under development as a joint project between France and Germany. The instrument is designed around CO2 laser technology, heterodyne detection, and a conical scanning of the line-of-site. The 10 micron domain is suitable for long range measurements due to the maturity of the technology and because it corresponds to an atmospheric window. The objectives of WIND are twofold: (1) to conduct mesoscale scientific studies in particular over oceanic and inhomogeneous terrain areas; and (2) to support the Earth-orbiting wind lidar projects.

Advanced technologies for future ground-based, laser-interferometric gravitational wave detectors

PubMed Central

Hammond, Giles; Hild, Stefan; Pitkin, Matthew

2014-01-01

We present a review of modern optical techniques being used and developed for the field of gravitational wave detection. We describe the current state-of-the-art of gravitational waves detector technologies with regard to optical layouts, suspensions and test masses. We discuss the dominant sources and noise in each of these subsystems and the developments that will help mitigate them for future generations of detectors. We very briefly summarise some of the novel astrophysics that will be possible with these upgraded detectors. PMID:25705087

Solar pumped laser technology options for space power transmission

NASA Technical Reports Server (NTRS)

Conway, E. J.

1986-01-01

An overview of long-range options for in-space laser power transmission is presented. The focus is on the new technology and research status of solar-pumped lasers and their solar concentration needs. The laser options include gas photodissociation lasers, optically-pumped solid-state lasers, and blackbody-pumped transfer lasers. The paper concludes with a summary of current research thrusts.

Site-resolved imaging of a bosonic Mott insulator using ytterbium atoms

NASA Astrophysics Data System (ADS)

Miranda, Martin; Inoue, Ryotaro; Tambo, Naoki; Kozuma, Mikio

2017-10-01

We demonstrate site-resolved imaging of a strongly correlated quantum system without relying on laser cooling techniques during fluorescence imaging. We observe the formation of Mott shells in the insulating regime and realize thermometry in an atomic cloud. This work proves the feasibility of the noncooled approach and opens the door to extending the detection technology to new atomic species.

Semiconducter Optical Amplifier as a Phase Modulator for Coherent Laser Radar (Preprint)

DTIC Science & Technology

2012-01-01

AIR FORCE RESEARCH LABORATORY SENSORS DIRECTORATE WRIGHT-PATTERSON AIR FORCE BASE, OH 45433-7320 AIR FORCE MATERIEL COMMAND UNITED STATES... AIR FORCE NOTICE AND SIGNATURE PAGE Using Government drawings, specifications, or other data included in this document for any purpose other...NUMBER Multispectral Sensing and Detection Division LADAR Technology Branch (AFRL/RYMM) Air Force Research Laboratory, Sensors Directorate Wright

Monitoring gully change: A comparison of airborne and terrestrial laser scanning using a case study from Aratula, Queensland

NASA Astrophysics Data System (ADS)

Goodwin, Nicholas R.; Armston, John D.; Muir, Jasmine; Stiller, Issac

2017-04-01

Airborne laser scanning (ALS) and terrestrial laser scanning (TLS) technologies capture spatially detailed estimates of surface topography and when collected multi-temporally can be used to assess geomorphic change. The sensitivity and repeatability of ALS measurements to characterise geomorphic change in topographically complex environments such as gullies; however, remains an area lacking quantitative research. In this study, we captured coincident ALS and TLS datasets to assess their ability and synergies to detect geomorphic change for a gully located in Aratula, southeast Queensland, Australia. We initially used the higher spatial density and ranging accuracy of TLS to provide an assessment of the Digital Elevation Models (DEM) derived from ALS within a gully environment. Results indicated mean residual errors of 0.13 and 0.09 m along with standard deviation (SD) of residual errors of 0.20 and 0.16 m using pixel sizes of 0.5 and 1.0 m, respectively. The positive mean residual errors confirm that TLS data consistently detected deeper sections of the gully than ALS. We also compared the repeatability of ALS and TLS for characterising gully morphology. This indicated that the sensitivity to detect change using ALS is substantially lower than TLS, as expected, and that the ALS survey characteristics influence the ability to detect change. Notably, we found that using one ALS transect (mean density of 5 points / m2) as opposed to three transects increased the SD of residual error by approximately 30%. The supplied classification of ALS ground points was also demonstrated to misclassify gully features as non-ground, with minimum elevation filtering found to provide a more accurate DEM of the gully. The number and placement of terrestrial laser scans were also found to influence the derived DEMs. Furthermore, we applied change detection using two ALS data captures over a four year period and four TLS field surveys over an eight month period. This demonstrated that ALS can detect large scale erosional changes with head cutting of gully branches migrating approximately 10 m upslope. In comparison, TLS captured smaller scale intra-annual erosional patterns largely undetectable by the ALS dataset with a large rainfall event coinciding with the highest volumetric change (net change > 46 m3). Overall, these findings reaffirm the importance of quantifying DEM errors and demonstrate that ALS is unlikely to detect subtle geomorphic changes (< 0.45 m) potentially missing significant sediment change. TLS was able to detect more subtle intra-annual changes but was limited in its spatial coverage. This suggests TLS and ALS surveys are complementary technologies and when used together can provide a more detailed understanding of gully processes at different temporal and spatial scales, provided the inherent errors are taken into account.

High-Fidelity Flash Lidar Model Development

NASA Technical Reports Server (NTRS)

Hines, Glenn D.; Pierrottet, Diego F.; Amzajerdian, Farzin

2014-01-01

NASA's Autonomous Landing and Hazard Avoidance Technologies (ALHAT) project is currently developing the critical technologies to safely and precisely navigate and land crew, cargo and robotic spacecraft vehicles on and around planetary bodies. One key element of this project is a high-fidelity Flash Lidar sensor that can generate three-dimensional (3-D) images of the planetary surface. These images are processed with hazard detection and avoidance and hazard relative navigation algorithms, and then are subsequently used by the Guidance, Navigation and Control subsystem to generate an optimal navigation solution. A complex, high-fidelity model of the Flash Lidar was developed in order to evaluate the performance of the sensor and its interaction with the interfacing ALHAT components on vehicles with different configurations and under different flight trajectories. The model contains a parameterized, general approach to Flash Lidar detection and reflects physical attributes such as range and electronic noise sources, and laser pulse temporal and spatial profiles. It also provides the realistic interaction of the laser pulse with terrain features that include varying albedo, boulders, craters slopes and shadows. This paper gives a description of the Flash Lidar model and presents results from the Lidar operating under different scenarios.

A method for detecting small targets based on cumulative weighted value of target properties

NASA Astrophysics Data System (ADS)

Jin, Xing; Sun, Gang; Wang, Wei-hua; Liu, Fang; Chen, Zeng-ping

2015-03-01

Laser detection based on the "cat's eye effect" has become the hot research project for its initiative compared to the passivity of sound detection and infrared detection. And the target detection is one of the core technologies in this system. The paper puts forward a method for detecting small targets based on cumulative weighted value of target properties using given data. Firstly, we make a frame difference to the images, then make image processing based on Morphology Principles. Secondly, we segment images, and screen the targets; then find some interesting locations. Finally, comparing to a quantity of frames, we locate the target. We did an exam to 394 true frames, the experimental result shows that the mathod can detect small targets efficiently.

The benefit of 3D laser scanning technology in the generation and calibration of FEM models for health assessment of concrete structures.

PubMed

Yang, Hao; Xu, Xiangyang; Neumann, Ingo

2014-11-19

Terrestrial laser scanning technology (TLS) is a new technique for quickly getting three-dimensional information. In this paper we research the health assessment of concrete structures with a Finite Element Method (FEM) model based on TLS. The goal focuses on the benefits of 3D TLS in the generation and calibration of FEM models, in order to build a convenient, efficient and intelligent model which can be widely used for the detection and assessment of bridges, buildings, subways and other objects. After comparing the finite element simulation with surface-based measurement data from TLS, the FEM model is determined to be acceptable with an error of less than 5%. The benefit of TLS lies mainly in the possibility of a surface-based validation of results predicted by the FEM model.

Hydrogen Research for Spaceport and Space-Based Applications: Hydrogen Production, Storage, and Transport. Part 3

NASA Technical Reports Server (NTRS)

Anderson, Tim; Balaban, Canan

2008-01-01

The activities presented are a broad based approach to advancing key hydrogen related technologies in areas such as fuel cells, hydrogen production, and distributed sensors for hydrogen-leak detection, laser instrumentation for hydrogen-leak detection, and cryogenic transport and storage. Presented are the results from research projects, education and outreach activities, system and trade studies. The work will aid in advancing the state-of-the-art for several critical technologies related to the implementation of a hydrogen infrastructure. Activities conducted are relevant to a number of propulsion and power systems for terrestrial, aeronautics and aerospace applications. Hydrogen storage and in-space hydrogen transport research focused on developing and verifying design concepts for efficient, safe, lightweight liquid hydrogen cryogenic storage systems. Research into hydrogen production had a specific goal of further advancing proton conducting membrane technology in the laboratory at a larger scale. System and process trade studies evaluated the proton conducting membrane technology, specifically, scale-up issues.

Optics detection and laser countermeasures on a combat vehicle

NASA Astrophysics Data System (ADS)

Sjöqvist, Lars; Allard, Lars; Pettersson, Magnus; Börjesson, Per; Lindskog, Nils; Bodin, Johan; Widén, Anders; Persson, Hâkan; Fredriksson, Jan; Edström, Sten

2016-10-01

Magnifying optical assemblies used for weapon guidance or rifle scopes may possess a threat for a combat vehicle and its personnel. Detection and localisation of optical threats is consequently of interest in military applications. Typically a laser system is used in optics detection, or optical augmentation, to interrogate a scene of interest to localise retroreflected laser radiation. One interesting approach for implementing optics detection on a combat vehicle is to use a continuous scanning scheme. In addition, optics detection can be combined with laser countermeasures, or a laser dazzling function, to efficiently counter an optical threat. An optics detection laser sensor demonstrator has been implemented on a combat vehicle. The sensor consists of a stabilised gimbal and was integrated together with a LEMUR remote electro-optical sight. A narrow laser slit is continuously scanned around the horizon to detect and locate optical threats. Detected threats are presented for the operator within the LEMUR presentation system, and by cueing a countermeasure laser installed in the LEMUR sensor housing threats can be defeated. Results obtained during a field demonstration of the optics detection sensor and the countermeasure laser will be presented. In addition, results obtained using a dual-channel optics detection system designed for false alarm reduction are also discussed.

In vivo stepwise multi-photon activation fluorescence imaging of melanin in human skin

NASA Astrophysics Data System (ADS)

Lai, Zhenhua; Gu, Zetong; Abbas, Saleh; Lowe, Jared; Sierra, Heidy; Rajadhyaksha, Milind; DiMarzio, Charles

2014-03-01

The stepwise multi-photon activated fluorescence (SMPAF) of melanin is a low cost and reliable method of detecting melanin because the activation and excitation can be a continuous-wave (CW) mode near infrared (NIR) laser. Our previous work has demonstrated the melanin SMPAF images in sepia melanin, mouse hair, and mouse skin. In this study, we show the feasibility of using SMPAF to detect melanin in vivo. in vivo melanin SMPAF images of normal skin and benign nevus are demonstrated. SMPAF images add specificity for melanin detection than MPFM images and CRM images. Melanin SMPAF is a promising technology to enable early detection of melanoma for dermatologists.

Simultaneous measurement of 2-dimensional H2O concentration and temperature distribution in premixed methane/air flame using TDLAS-based tomography technology

NASA Astrophysics Data System (ADS)

Wang, Fei; Wu, Qi; Huang, Qunxing; Zhang, Haidan; Yan, Jianhua; Cen, Kefa

2015-07-01

An innovative tomographic method using tunable diode laser absorption spectroscopy (TDLAS) and algebraic reconstruction technique (ART) is presented in this paper for detecting two-dimensional distribution of H2O concentration and temperature in a premixed flame. The collimated laser beam emitted from a low cost diode laser module was delicately split into 24 sub-beams passing through the flame from different angles and the acquired laser absorption signals were used to retrieve flame temperature and H2O concentration simultaneously. The efficiency of the proposed reconstruction system and the effect of measurement noise were numerically evaluated. The temperature and H2O concentration in flat methane/air premixed flames under three different equivalence ratios were experimentally measured and reconstruction results were compared with model calculations. Numerical assessments indicate that the TDLAS tomographic system is capable for temperature and H2O concentration profiles detecting even the noise strength reaches 3% of absorption signal. Experimental results under different combustion conditions are well demonstrated along the vertical direction and the distribution profiles are in good agreement with model calculation. The proposed method exhibits great potential for 2-D or 3-D combustion diagnostics including non-uniform flames.

Efficient generation of twin photons at telecom wavelengths with 2.5 GHz repetition-rate-tunable comb laser

PubMed Central

Jin, Rui-Bo; Shimizu, Ryosuke; Morohashi, Isao; Wakui, Kentaro; Takeoka, Masahiro; Izumi, Shuro; Sakamoto, Takahide; Fujiwara, Mikio; Yamashita, Taro; Miki, Shigehito; Terai, Hirotaka; Wang, Zhen; Sasaki, Masahide

2014-01-01

Efficient generation and detection of indistinguishable twin photons are at the core of quantum information and communications technology (Q-ICT). These photons are conventionally generated by spontaneous parametric down conversion (SPDC), which is a probabilistic process, and hence occurs at a limited rate, which restricts wider applications of Q-ICT. To increase the rate, one had to excite SPDC by higher pump power, while it inevitably produced more unwanted multi-photon components, harmfully degrading quantum interference visibility. Here we solve this problem by using recently developed 10 GHz repetition-rate-tunable comb laser, combined with a group-velocity-matched nonlinear crystal, and superconducting nanowire single photon detectors. They operate at telecom wavelengths more efficiently with less noises than conventional schemes, those typically operate at visible and near infrared wavelengths generated by a 76 MHz Ti Sapphire laser and detected by Si detectors. We could show high interference visibilities, which are free from the pump-power induced degradation. Our laser, nonlinear crystal, and detectors constitute a powerful tool box, which will pave a way to implementing quantum photonics circuits with variety of good and low-cost telecom components, and will eventually realize scalable Q-ICT in optical infra-structures. PMID:25524646

Rapid calibrated high-resolution hyperspectral imaging using tunable laser source

NASA Astrophysics Data System (ADS)

Nguyen, Lam K.; Margalith, Eli

2009-05-01

We present a novel hyperspectral imaging technique based on tunable laser technology. By replacing the broadband source and tunable filters of a typical NIR imaging instrument, several advantages are realized, including: high spectral resolution, highly variable field-of-views, fast scan-rates, high signal-to-noise ratio, and the ability to use optical fiber for efficient and flexible sample illumination. With this technique, high-resolution, calibrated hyperspectral images over the NIR range can be acquired in seconds. The performance of system features will be demonstrated on two example applications: detecting melamine contamination in wheat gluten and separating bovine protein from wheat protein in cattle feed.

Frequency domain laser velocimeter signal processor

NASA Technical Reports Server (NTRS)

Meyers, James F.; Murphy, R. Jay

1991-01-01

A new scheme for processing signals from laser velocimeter systems is described. The technique utilizes the capabilities of advanced digital electronics to yield a signal processor capable of operating in the frequency domain maximizing the information obtainable from each signal burst. This allows a sophisticated approach to signal detection and processing, with a more accurate measurement of the chirp frequency resulting in an eight-fold increase in measurable signals over the present high-speed burst counter technology. Further, the required signal-to-noise ratio is reduced by a factor of 32, allowing measurements within boundary layers of wind tunnel models. Measurement accuracy is also increased up to a factor of five.

Precision Spectroscopy, Diode Lasers, and Optical Frequency Measurement Technology

NASA Technical Reports Server (NTRS)

Hollberg, Leo (Editor); Fox, Richard (Editor); Waltman, Steve (Editor); Robinson, Hugh

1998-01-01

This compilation is a selected set of reprints from the Optical Frequency Measurement Group of the Time and Frequency Division of the National Institute of Standards and Technology, and consists of work published between 1987 and 1997. The two main programs represented here are (1) development of tunable diode-laser technology for scientific applications and precision measurements, and (2) research toward the goal of realizing optical-frequency measurements and synthesis. The papers are organized chronologically in five, somewhat arbitrarily chosen categories: Diode Laser Technology, Tunable Laser Systems, Laser Spectroscopy, Optical Synthesis and Extended Wavelength Coverage, and Multi-Photon Interactions and Optical Coherences.

Tenth Biennial Coherent Laser Radar Technology and Applications Conference

NASA Technical Reports Server (NTRS)

Kavaya, Michael J. (Compiler)

1999-01-01

The tenth conference on coherent laser radar technology and applications is the latest in a series beginning in 1980 which provides a forum for exchange of information on recent events current status, and future directions of coherent laser radar (or lidar or lader) technology and applications. This conference emphasizes the latest advancement in the coherent laser radar field, including theory, modeling, components, systems, instrumentation, measurements, calibration, data processing techniques, operational uses, and comparisons with other remote sensing technologies.

Solid-State, High Energy 2-Micron Laser Development for Space-Based Remote Sensing

NASA Technical Reports Server (NTRS)

Singh, Upendra N.

2010-01-01

Lidar (light detection and ranging) remote sensing enjoys the advantages of excellent vertical and horizontal resolution; pointing capability; a signal source independent from natural light; and control and knowledge of transmitted wavelength, pulse shape, and polarization and received polarization. Lidar in space is an emerging technology now being developing to fit applications where passive sensors cannot meet current measurement requirements. Technical requirements for space lidar are more demanding than for ground-based or airborne systems. Perhaps the most distinguishing characteristics of space lidars are the environmental requirements. Space lidar systems must be specially designed to survive the mechanical vibration loads of launch and operate in the vacuum of space where exposure to ionizing radiation limits the electronic components available. Finally, space lidars must be designed to be highly reliable because they must operate without the need for repair or adjustment. Lifetime requirements tend to be important drivers of the overall system design. The maturity of the required technologies is a key to the development of any space lidar system. NASA entered a new era in the 1990 s with the approval of several space-based remote sensing missions employing laser radar (lidar) techniques. Following the steps of passive remote sensing and then active radar remote sensing, lidar sensors were a logical next step, providing independence from natural light sources, and better spatial resolution and smaller sensor size than radar sensors. The shorter electromagnetic wavelengths of laser light also allowed signal reflectance from air molecules and aerosol particles. The smaller receiver apertures allowed the concept of scanning the sensor field of view. However, technical problems with several space-based lidar missions during that decade led to concern at NASA about the risk of lidar missions. An external panel was convened to make recommendations to NASA. Their report in 2000 strongly advocated that NASA maintain in-house laser and lidar capability, and that NASA should work to lower the technology risk for all future lidar missions. A multi-Center NASA team formulated an integrated NASA strategy to provide the technology and maturity of systems necessary to make Lidar/Laser systems viable for space-based study and monitoring of the Earth's atmosphere. In 2002 the NASA Earth Science Enterprise (ESE) and Office of Aerospace Technology (OAT) created the Laser Risk Reduction Program (LRRP) and directed NASA Langley Research Center (LaRC) and Goddard Space Flight Center to carry out synergistic and complementary research towards solid-state lasers/lidars developments for space-based remote sensing applications.

Laser Ignition Technology for Bi-Propellant Rocket Engine Applications

NASA Technical Reports Server (NTRS)

Thomas, Matt; Bossard, John; Early, Jim; Trinh, Huu; Dennis, Jay; Turner, James (Technical Monitor)

2001-01-01

This viewgraph presentation gives an overview of laser ignition technology for bipropellant rocket engines applications. The objectives of this project include: (1) the selection test chambers and flows; (2) definition of the laser ignition setup; (3) pulse format optimization; (4) fiber optic coupled laser ignition system analysis; and (5) chamber integration issues definition. The testing concludes that rocket combustion chamber laser ignition is imminent. Support technologies (multiplexing, window durability/cleaning, and fiber optic durability) are feasible.

Joining Pipe with the Hybrid Laser-GMAW Process: Weld Test Results and Cost Analysis

DTIC Science & Technology

2006-06-01

Recent work investigating the poten- tial benefit of applying this technology to a shipyard pipe shop suggests that signifi- cant cost savings may be...arc-based joining processes. With recent advances in com- mercial laser technology , laser suppliers can now deliver dramatically higher power systems...reasons, shipyards in the U.S. are showing growing interest in hybrid laser-GMA welding technology . Hybrid Laser-GMA for Joining Pipe Welding of pipe

Laser-ultrasonic technologies for medicine

NASA Astrophysics Data System (ADS)

Zharov, Vladimir P.; Latyshev, Alexei S.

1999-06-01

This review tackles the problem of further developing laser- ultrasonic medical technologies and gives the comparison of different laser and ultrasound combinations. The features of combined influence on biotissue are explicated with due regard for mechanic, ultrasonic (US), and thermal effects. The review present the effect of self-cleaning an optical fiber tip from the laser destruction products of biotissue, the result of research on the possibility of laser-US technology applications in endoscopy, and the ways of suppressing unwanted bending oscillations. Various spheres and peculiarities of applying laser-US technologies are discussed, including microsurgery, cosmetology, transcutaneous drug delivery, and the treatment of chronic prostatitis and infected wounds. Furthermore, the analysis of transcutaneous drug delivery methods employing a portable pulsed Er:YAG laser is presented. Drug diffusion has been shown to be enhanced under acoustic and US effects. The photo-vacuum drug injection mechanism recently suggested is discussed. It turned out that laser-US technology can be suitable for both impregnating the photosensitizer in local photodynamic therapy procedures and conducting microsurgery operations involving drug injection. Treatment of infectious processes based on the bactericidal action of photosensitizers and ultrasound due to the cavitation effect in solutions is described. An additional therapeutic effect can be achieved via the US intermingling of solutions with their simulations illumination by a matrix of red lasers or light diodes. An outlook on further developing laser-US technology and the ways of its apparatus realization are considered.

The economics of surgical laser technology in veterinary practice.

PubMed

Irwin, James R

2002-05-01

A decision to invest in and develop laser technology should only be made after a thorough investigation and comparison of the available types, vendors, available features, and purchasing options. A sound marketing program must then be used for introducing laser technology to the staff, clients, and colleagues. Without adhering to such a program, a practice will [figure: see text] not experience the necessary profitability following the purchase of a laser. Staff enthusiasm and support will dwindle, and ultimately the laser investment will be viewed unfavorably. When marketed properly, however, the investment in a surgical laser will provide outstanding profitability. The return on investment can be provided by using the support staff for client education, by offering laser technology for routine elective procedures and complex procedures, and by adhering strictly to a fee schedule. Add that to the truly remarkable results obtained using laser surgical techniques, a practice will be greatly enhanced.

Evolution of laser skin resurfacing: from scanning to fractional technology.

PubMed

Aslam, Arif; Alster, Tina S

2014-11-01

Laser skin resurfacing was popularized for photoaged and scarred skin 2 decades ago. Since then, several technologic advancements have led to a new generation of delivery systems that produce excellent clinical outcomes with reduced treatment risks and faster recovery times. To review the evolution of laser skin resurfacing from pulsed and scanned infrared laser technology to the latest techniques of nonablative and ablative fractional photothermolysis. All published literature regarding laser skin resurfacing was analyzed and collated. A comprehensive review of laser skin resurfacing was outlined and future developments in the field of fractionated laser skin treatment were introduced. Laser skin resurfacing has evolved such that excellent clinical outcomes in photodamaged and scarred skin are achieved with rapid wound healing. As newer devices are developed, the applications of this technology will have a dramatic effect on the delivery of medical and aesthetic dermatology.

Laser Detection of Pollution.

ERIC Educational Resources Information Center

Patel, C. K. N.

1978-01-01

Discusses the use of laser spectroscopy in determining the presence of specific gaseous constituents. Three of currently used modes for laser detection of pollution are reviewed; (1) long-path measurements; (2) laser raman (differential absorption) measurements; and (3) optoacoustic detection. (HM)

Multivariate analysis of standoff laser-induced breakdown spectroscopy spectra for classification of explosive-containing residues

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

De Lucia, Frank C. Jr.; Gottfried, Jennifer L.; Munson, Chase A.

2008-11-01

A technique being evaluated for standoff explosives detection is laser-induced breakdown spectroscopy (LIBS). LIBS is a real-time sensor technology that uses components that can be configured into a ruggedized standoff instrument. The U.S. Army Research Laboratory has been coupling standoff LIBS spectra with chemometrics for several years now in order to discriminate between explosives and nonexplosives. We have investigated the use of partial least squares discriminant analysis (PLS-DA) for explosives detection. We have extended our study of PLS-DA to more complex sample types, including binary mixtures, different types of explosives, and samples not included in the model. We demonstrate themore » importance of building the PLS-DA model by iteratively testing it against sample test sets. Independent test sets are used to test the robustness of the final model.« less

THz-wave parametric sources and imaging applications

NASA Astrophysics Data System (ADS)

Kawase, Kodo

2004-12-01

We have studied the generation of terahertz (THz) waves by optical parametric processes based on laser light scattering from the polariton mode of nonlinear crystals. Using parametric oscillation of MgO-doped LiNbO3 crystal pumped by a nano-second Q-switched Nd:YAG laser, we have realized a widely tunable coherent THz-wave sources with a simple configuration. We have also developed a novel basic technology for THz imaging, which allows detection and identification of chemicals by introducing the component spatial pattern analysis. The spatial distributions of the chemicals were obtained from terahertz multispectral trasillumination images, using absorption spectra previously measured with a widely tunable THz-wave parametric oscillator. Further we have applied this technique to the detection and identification of illicit drugs concealed in envelopes. The samples we used were methamphetamine and MDMA, two of the most widely consumed illegal drugs in Japan, and aspirin as a reference.

Laser-induced breakdown spectroscopy for detection of heavy metals in environmental samples

NASA Astrophysics Data System (ADS)

Wisbrun, Richard W.; Schechter, Israel; Niessner, Reinhard; Schroeder, Hartmut

1993-03-01

The application of LIBS technology as a sensor for heavy metals in solid environmental samples has been studied. This specific application introduces some new problems in the LIBS analysis. Some of them are related to the particular distribution of contaminants in the grained samples. Other problems are related to mechanical properties of the samples and to general matrix effects, like the water and organic fibers content of the sample. An attempt has been made to optimize the experimental set-up for the various involved parameters. The understanding of these factors has enabled the adjustment of the technique to the substrates of interest. The special importance of the grain size and of the laser-induced aerosol production is pointed out. Calibration plots for the analysis of heavy metals in diverse sand and soil samples have been carried out. The detection limits are shown to be usually below the recent regulation restricted concentrations.

Interplanetary and interstellar optical communication between intelligent beings: a historical approach

NASA Astrophysics Data System (ADS)

Lemarchand, Guillermo A.

1996-06-01

A review of the different proposals made to establish contact with hypothetical planetary neighbors is done. For almost 100 years (approximately 1822-1921) the dominant paradigm for signaling extraterrestrial beings, were based in the exchange of light beam signals. After the success of wireless transatlantic communications and the discovery of radio signals from the cosmos, the main scientific proposals to contact extraterrestrials were based on radio signals. Nevertheless, the development of lasers and other nonlinear optical devices, led into a new set of proposals to use them for interplanetary and interstellar communication means. A review of these proposals and the detection of extraterrestrial technological activities in the optical domain is made. A summary of the requirements needed to explore the astrophysics of shortest timescales is described, in order to develop the nano and sub-nanosecond detectors that could be used to detect interstellar pulsed laser signals.

Mobile 3D laser scanning technology application in the surveying of urban underground rail transit

NASA Astrophysics Data System (ADS)

Han, Youmei; Yang, Bogang; Zhen, Yinan

2016-11-01

Mobile 3D laser scanning technology is one hot kind of digital earth technology. 3D completion surveying is relative new concept in surveying and mapping. A kind of mobile 3D laser scanning system was developed for the urban underground rail 3D completion surveying. According to the characteristics of underground rail environment and the characters of the mobile laser scanning system, it designed a suitable test scheme to improving the accuracy of this kind of mobile laser scanning system when it worked under no GPS signal environment. Then it completed the application of this technology in the No.15 rail 3D completion surveying. Meanwhile a set of production process was made for the 3D completion surveying based on this kind of mobile 3D laser scanning technology. These products were also proved the efficiency of the new technology in the rail 3D completion surveying. Using mobile 3D laser scanning technology to complete underground rail completion surveying has been the first time in China until now. It can provide a reference for 3D measurement of rail completion surveying or the 3D completion surveying of other areas.

Advanced Laser Architecture for Two-Step Laser Tandem Mass Spectrometer

NASA Technical Reports Server (NTRS)

Fahey, Molly E.; Li, Steven X.; Yu, Anthony W.; Getty, Stephanie A.

2016-01-01

Future astrobiology missions will focus on planets with significant astrochemical or potential astrobiological features, such as small, primitive bodies and the icy moons of the outer planets that may host diverse organic compounds. These missions require advanced instrument techniques to fully and unambiguously characterize the composition of surface and dust materials. Laser desorptionionization mass spectrometry (LDMS) is an emerging instrument technology for in situ mass analysis of non-volatile sample composition. A recent Goddard LDMS advancement is the two-step laser tandem mass spectrometer (L2MS) instrument to address the need for future flight instrumentation to deconvolve complex organic signatures. The L2MS prototype uses a resonance enhanced multi-photon laser ionization mechanism to selectively detect aromatic species from a more complex sample. By neglecting the aliphatic and inorganic mineral signatures in the two-step mass spectrum, the L2MS approach can provide both mass assignments and clues to structural information for an in situ investigation of non-volatile sample composition. In this paper we will describe our development effort on a new laser architecture that is based on the previously flown Lunar Orbiter Laser Altimeter (LOLA) laser transmitter for the L2MS instrument. The laser provides two discrete midinfrared wavelengths (2.8 m and 3.4 m) using monolithic optical parametric oscillators and ultraviolet (UV) wavelength (266 nm) on a single laser bench with a straightforward development path toward flight readiness.

Random lasers for lab-on-chip applications

NASA Astrophysics Data System (ADS)

Giehl, J. M.; Butzbach, F.; Jorge, K. C.; Alvarado, M. A.; Carreño, M. N. P.; Alayo, M. I.; Wetter, N. U.

2016-04-01

Random lasers are laser sources in which the feedback is provided by scattering instead of reflection and which, for this reason, do not require surfaces with optical finish such as mirrors. The investigation of such lasing action in a large variety of disordered materials is a subject of high interest with very important applications such as threedimensional and speckle-free imaging, detection of cancer tissue and photonic coding and encryption. However, potential applications require optimization of random laser performance especially with respect to optical efficiency and directionality or brightness. This work demonstrates such an optimization procedure with the goal of achieving a random laser with sufficient efficiency and brightness in order to be used in practical applications. Two random lasers are demonstrated, one solid and on liquid, that fulfil directionality and efficiency requirements. The first one consists of a neodymium doped powder laser with a record slope efficiency of 1.6%. The second one is a liquid random laser injected into a HC-ARROW waveguide which uses a microchannel connected to a much larger reservoir in order to achieve the necessary directionality. Both devices can be produced by low cost fabricating technologies and easily integrated into next-generation, lab-on-chip devices used for in-situ determination of infectious tropical diseases, which is the main goal of this project.

Development of a Fiber Laser with Independently Adjustable Properties for Optical Resolution Photoacoustic Microscopy.

PubMed

Aytac-Kipergil, Esra; Demirkiran, Aytac; Uluc, Nasire; Yavas, Seydi; Kayikcioglu, Tunc; Salman, Sarper; Karamuk, Sohret Gorkem; Ilday, Fatih Omer; Unlu, Mehmet Burcin

2016-12-08

Photoacoustic imaging is based on the detection of generated acoustic waves through thermal expansion of tissue illuminated by short laser pulses. Fiber lasers as an excitation source for photoacoustic imaging have recently been preferred for their high repetition frequencies. Here, we report a unique fiber laser developed specifically for multiwavelength photoacoustic microscopy system. The laser is custom-made for maximum flexibility in adjustment of its parameters; pulse duration (5-10 ns), pulse energy (up to 10 μJ) and repetition frequency (up to 1 MHz) independently from each other and covers a broad spectral region from 450 to 1100 nm and also can emit wavelengths of 532, 355, and 266 nm. The laser system consists of a master oscillator power amplifier, seeding two stages; supercontinuum and harmonic generation units. The laser is outstanding since the oscillator, amplifier and supercontinuum generation parts are all-fiber integrated with custom-developed electronics and software. To demonstrate the feasibility of the system, the images of several elements of standardized resolution test chart are acquired at multiple wavelengths. The lateral resolution of optical resolution photoacoustic microscopy system is determined as 2.68 μm. The developed system may pave the way for spectroscopic photoacoustic microscopy applications via widely tunable fiber laser technologies.

Development of a Fiber Laser with Independently Adjustable Properties for Optical Resolution Photoacoustic Microscopy

PubMed Central

Aytac-Kipergil, Esra; Demirkiran, Aytac; Uluc, Nasire; Yavas, Seydi; Kayikcioglu, Tunc; Salman, Sarper; Karamuk, Sohret Gorkem; Ilday, Fatih Omer; Unlu, Mehmet Burcin

2016-01-01

Photoacoustic imaging is based on the detection of generated acoustic waves through thermal expansion of tissue illuminated by short laser pulses. Fiber lasers as an excitation source for photoacoustic imaging have recently been preferred for their high repetition frequencies. Here, we report a unique fiber laser developed specifically for multiwavelength photoacoustic microscopy system. The laser is custom-made for maximum flexibility in adjustment of its parameters; pulse duration (5–10 ns), pulse energy (up to 10 μJ) and repetition frequency (up to 1 MHz) independently from each other and covers a broad spectral region from 450 to 1100 nm and also can emit wavelengths of 532, 355, and 266 nm. The laser system consists of a master oscillator power amplifier, seeding two stages; supercontinuum and harmonic generation units. The laser is outstanding since the oscillator, amplifier and supercontinuum generation parts are all-fiber integrated with custom-developed electronics and software. To demonstrate the feasibility of the system, the images of several elements of standardized resolution test chart are acquired at multiple wavelengths. The lateral resolution of optical resolution photoacoustic microscopy system is determined as 2.68 μm. The developed system may pave the way for spectroscopic photoacoustic microscopy applications via widely tunable fiber laser technologies. PMID:27929049

Five Strategies for Detecting Intelligence

NASA Astrophysics Data System (ADS)

Tough, Allen

If highly intelligent life has evolved elsewhere in our galaxy, how might scientists detect it? This paper compares eleven search strategies on three dimensions. Which strategies are most likely to detect extraterrestrial intelligence or technology? Which strategies, if successful, will likely contribute a wealth of knowledge? What is the current status of actual projects? In order to detect evidence of extraterrestrial intelligence or technology many light-years from Earth, astronomers can search for (1) radio signals, using various approaches, (2) laser or other optical signals, (3) other incoming signals, or (4) signs of an astroengineering project or Dyson sphere. Scientists could also (5) broadcast a radio message asking distant civilizations to respond. Additional strategies arise because any civilizations in our galaxy are probably much older than us and will therefore have technology far beyond ours. A technologically sophisticated civilization could likely send a small but super-smart probe to explore our solar system. An alien probe in our solar system, beyond the Moon, might be detected (6) by ongoing astronomy and space exploration, or (7) by a dedicated search for evidence of a probe or its byproducts. If a super-smart probe has reached Earth, it might be detected (8) by routine military and intelligence monitoring, (9) by an invitation to ETI on the World Wide Web, (10) by achieving peace or some other threshold that the probe requires before contact, or (11) by developing rigorous new research designs to study anomalous phenomena.

A Career in Laser Technology.

ERIC Educational Resources Information Center

Burns, William E.

1986-01-01

The increased expansion of laser technology will create many new jobs and will require workers with many different skills. At the same time, some kinds of occupations will be adversely affected, due to increasing use of laser technology in a broad range of industries. (CT)

Recognition of edible oil by using BP neural network and laser induced fluorescence spectrum

NASA Astrophysics Data System (ADS)

Mu, Tao-tao; Chen, Si-ying; Zhang, Yin-chao; Guo, Pan; Chen, He; Zhang, Hong-yan; Liu, Xiao-hua; Wang, Yuan; Bu, Zhi-chao

2013-09-01

In order to accomplish recognition of the different edible oil we set up a laser induced fluorescence spectrum system in the laboratory based on Laser induced fluorescence spectrum technology, and then collect the fluorescence spectrum of different edible oil by using that system. Based on this, we set up a fluorescence spectrum database of different cooking oil. It is clear that there are three main peak position of different edible oil from fluorescence spectrum chart. Although the peak positions of all cooking oil were almost the same, the relative intensity of different edible oils was totally different. So it could easily accomplish that oil recognition could take advantage of the difference of relative intensity. Feature invariants were extracted from the spectrum data, which were chosen from the fluorescence spectrum database randomly, before distinguishing different cooking oil. Then back propagation (BP) neural network was established and trained by the chosen data from the spectrum database. On that basis real experiment data was identified by BP neural network. It was found that the overall recognition rate could reach as high as 83.2%. Experiments showed that the laser induced fluorescence spectrum of different cooking oil was very different from each other, which could be used to accomplish the oil recognition. Laser induced fluorescence spectrum technology, combined BP neural network，was fast, high sensitivity, non-contact, and high recognition rate. It could become a new technique to accomplish the edible oil recognition and quality detection.

A novel effective method for the assessment of microvascular function in male patients with coronary artery disease: a pilot study using laser speckle contrast imaging.

PubMed

Borges, J P; Lopes, G O; Verri, V; Coelho, M P; Nascimento, P M C; Kopiler, D A; Tibirica, E

2016-09-01

Evaluation of microvascular endothelial function is essential for investigating the pathophysiology and treatment of cardiovascular and metabolic diseases. Although laser speckle contrast imaging technology is well accepted as a noninvasive methodology for assessing microvascular endothelial function, it has never been used to compare male patients with coronary artery disease with male age-matched healthy controls. Thus, the aim of this study was to determine whether laser speckle contrast imaging could be used to detect differences in the systemic microvascular functions of patients with established cardiovascular disease (n=61) and healthy age-matched subjects (n=24). Cutaneous blood flow was assessed in the skin of the forearm using laser speckle contrast imaging coupled with the transdermal iontophoretic delivery of acetylcholine and post-occlusive reactive hyperemia. The maximum increase in skin blood flow induced by acetylcholine was significantly reduced in the cardiovascular disease patients compared with the control subjects (74 vs 116%; P<0.01). With regard to post-occlusive reactive hyperemia-induced vasodilation, the patients also presented reduced responses compared to the controls (0.42±0.15 vs 0.50±0.13 APU/mmHg; P=0.04). In conclusion, laser speckle contrast imaging can identify endothelial and microvascular dysfunctions in male individuals with cardiovascular disease. Thus, this technology appears to be an efficient non-invasive technique for evaluating systemic microvascular and endothelial functions, which could be valuable as a peripheral marker of atherothrombotic diseases in men.

Laser Interferometry for Gravitational Wave Observation: LISA and LISA Pathfinder

NASA Technical Reports Server (NTRS)

Guzman, Felipe

2010-01-01

The Laser Interferometer Space Antenna (LISA) is a planned NASA-ESA gravitational wave observatory in the frequency range of 0.1mHz-100mHz. This observation band is inaccessible to ground-based detectors due to the large ground motions of the Earth. Gravitational wave sources for LISA include galactic binaries, mergers of supermasive black-hole binaries, extreme-mass-ratio inspirals, and possibly from as yet unimagined sources. LISA is a constellation of three spacecraft separated by 5 million km in an equilateral triangle, whose center follows the Earth in a heliocentric orbit with an orbital phase offset oF 20 degrees. Challenging technology is required to ensure pure geodetic trajectories of the six onboard test masses, whose distance fluctuations will be measured by interspacecraft laser interferometers with picometer accuracy. LISA Pathfinder is an ESA-launched technology demonstration mission of key LISA subsystems such us spacecraft control with micro-newton thrusters, test mass drag-free control, and precision laser interferometry between free-flying test masses. Ground testing of flight hardware of the Gravitational Reference Sensor and Optical Metrology subsystems of LISA Pathfinder is currently ongoing. An introduction to laser interferometric gravitational wave detection, ground-based observatories, and a detailed description of the two missions together with an overview of current investigations conducted by the community will bc discussed. The current status in development and implementation of LISA Pathfinder pre-flight systems and latest results of the ongoing ground testing efforts will also be presented

LLE 1998 annual report, October 1997--September 1998. Inertial fusion program and National Laser Users` Facility program

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

NONE

1999-01-01

This report summarizes research at the Laboratory for Laser Energetics (LLE), the operation of the National Laser Users` Facility (NLUF), and programs involving the education of high school, undergraduate, and graduate students for FY98. Research summaries cover: progress in laser fusion; diagnostic development; laser and optical technology; and advanced technology for laser targets.

Reviews on laser cutting technology for industrial applications

NASA Astrophysics Data System (ADS)

Muangpool, T.; Pullteap, S.

2018-03-01

In this paper, an overview of the laser technology applied for the industrial has been reviewed. In general, this technology was used in several engineering applications such as industrial, medical, science, research sectors, etc. Focusing on the laser technology in the industrial section, it was, normally, employed for many purposes i.e. target marking, welding, drilling, and also cutting. Consequently, the laser cutting technology was, however, divided into three classifications YAG, CO2, and fiber laser, respectively. Each laser types have different advantages and disadvantages depending on the material type. The advantages by using laser cutting compared with the general cutting machines were exploited in terms of narrow kerf, high cutting speed, low heat-affected zone (HAZ), improve efficiency of the cutting process, high accuracy, etc. However, the main objectives from the technology used were increasing of the products and also decreasing the production cost. In the opposite way, some disadvantages of the technology were summarized by complexity to operate, high maintenance cost, and also high power consumption. In Thailand industry, there were many factories used this technology as a cutting process. Unfortunately, only few researches were published. It might explains that this technology were difficulty to develop, high investment, and also easy to import from aboard. For becoming to the Thailand 4.0 community, the Thailand industry might awareness to reduce the importing machine and boosting some policies to create novel innovative / know-how from the own country.

Present and future trends of laser materials processing in Japan

NASA Astrophysics Data System (ADS)

Matsunawa, Akira

1991-10-01

Lasers quickly penetrated into Japanese industries in the mid-80s. The paper reviews the present situation of industrial lasers and their applications in Japanese industries for materials removal, joining, and some surface modification technologies as well as their economical evaluation compared with competitive technologies. Laser cutting of metallic and nonmetallic thin sheets is widely prevalent even in small scale industries as a flexible manufacturing tool. As for the laser welding is concerned, industrial applications are rather limited in mass production lines. This mainly comes from the fact that the present laser technologies have not employed the adaptive control because of the lack of sensors, monitoring, and control systems which can tolerate the high-precision and high-speed processing. In spite of this situation, laser welding is rapidly increasing in recent years in industries such as automotive, machinery, electric/electronic, steel, heavy industries, etc. Laser surface modification technologies have attracted significant interest from industrial people, but actual application is very limited today. However, the number of R&D papers is increasing year by year. The paper also reviews these new technology trends in Japan.

Obstacle detection and avoiding of quadcopter

NASA Astrophysics Data System (ADS)

Wang, Dizhong; Lin, Jiajian

2017-10-01

Recent years, the flight control technology over quadcopter has been boosted vigorously and acquired the comprehensive application in a variety of industries. However, it is prominent for there to be problems existed in the stable and secure flight with the development of its autonomous flight. Through comparing with the characteristics of ultrasonic ranging and laser Time-of-Flight(abbreviated to ToF) distance as well as vision measurement and its related sensors, the obstacle detection and identification sensors need to be installed in order to effectively enhance the safety flying for aircraft, which is essential for avoiding the dangers around the surroundings. That the major sensors applied to objects perception at present are distance measuring instruments which based on the principle and application of non-contact detection technology . Prior to acknowledging the general principles of flight and obstacle avoiding, the aerodynamics modeling of the quadcopter and its object detection means has been initially determined on this paper. Based on such premise, this article emphasized on describing and analyzing the research on obstacle avoiding technology and its application status, and making an expectation for the trend of its development after analyzing the primary existing problems concerning its accuracy object avoidance.

Vacuum decay container/closure integrity testing technology. Part 2. Comparison to dye ingress tests.

PubMed

Wolf, Heinz; Stauffer, Tony; Chen, Shu-Chen Y; Lee, Yoojin; Forster, Ronald; Ludzinski, Miron; Kamat, Madhav; Mulhall, Brian; Guazzo, Dana Morton

2009-01-01

Part 1 of this series demonstrated that a container closure integrity test performed according to ASTM F2338-09 Standard Test Method for Nondestructive Detection of Leaks in Packages by Vacuum Decay Method using a VeriPac 325/LV vacuum decay leak tester by Packaging Technologies & Inspection, LLC (PTI) is capable of detecting leaks > or = 5.0 microm (nominal diameter) in rigid, nonporous package systems, such as prefilled glass syringes. The current study compared USP, Ph.Eur. and ISO dye ingress integrity test methods to PTI's vacuum decay technology for the detection of these same 5-, 10-, and 15-microm laser-drilled hole defects in 1-mL glass prefilled syringes. The study was performed at three test sites using several inspectors and a variety of inspection conditions. No standard dye ingress method was found to reliably identify all holed syringes. Modifications to these standard dye tests' challenge conditions increased the potential for dye ingress, and adjustments to the visual inspection environment improved dye ingress detection. However, the risk of false positive test results with dye ingress tests remained. In contrast, the nondestructive vacuum decay leak test method reliably identified syringes with holes > or = 5.0 microm.

Innovation Study for Laser Cutting of Complex Geometries with Paper Materials

NASA Astrophysics Data System (ADS)

Happonen, A.; Stepanov, A.; Piili, H.; Salminen, A.

Even though technology for laser cutting of paper materials has existed for over 30 years, it seems that results of applications of this technology and possibilities of laser cutting systems are not easily available. The aim of this study was to analyze the feasibility of the complex geometry laser cutting of paper materials and to analyze the innovation challenges and potential of current laser cutting technologies offer. This research studied the potential and possible challenges in applying CO2 laser cutting technology for cutting of paper materials in current supply chains trying to fulfil the changing needs of customer in respect of shape, fast response during rapid delivery cycle. The study is focused on examining and analyzing the different possibilities of laser cutting of paper material in application area of complex low volume geometry cutting. The goal of this case was to analyze the feasibility of the laser cutting from technical, quality and implementation points of view and to discuss availability of new business opportunities. It was noticed that there are new business models still available within laser technology applications in complex geometry cutting. Application of laser technology, in business-to-consume markets, in synergy with Internet service platforms can widen the customer base and offer new value streams for technology and service companies. Because of this, existing markets and competition has to be identified, and appropriate new and innovative business model needs to be developed. And to be competitive in the markets, models like these need to include the earning logic and the stages from production to delivery as discussed in the paper.

Laser-induced capillary leakage for blood biomarker detection and vaccine delivery via the skin.

PubMed

Wu, Jeffrey H; Li, Bo; Wu, Mei X

2016-07-01

Circulation system is the center for coordination and communication of all organs in our body. Examination of any change in its analytes or delivery of therapeutic drugs into the system consists of important medical practice in today's medicine. Two recent studies prove that brief illumination of skin with a low powered laser, at wavelengths preferentially absorbed by hemoglobin, increases the amount of circulating biomarkers in the epidermis and upper dermis by more than 1,000-fold. When probe-coated microneedle arrays are applied into laser-treated skin, plasma blood biomarkers can be reliably, accurately, and sufficiently quantified in 15∼30 min assays, with a maximal detection in one hr in a manner independent of penetration depth or a molecular mass of the biomarker. Moreover, the laser treatment permits a high efficient delivery of radiation-attenuated malarial sporozoites (RAS) into the circulation, leading to robust immunity against malaria infections, whereas similar immunization at sham-treated skin elicits poor immune responses. Thus this technology can potentially instruct designs of small, portable devices for onsite, in mobile clinics, or at home for point-of-care diagnosis and drug/vaccine delivery via the skin. Laser-induced capillary leakage (a) to induce extravasation of circualing molecules only (b) or facilitate entry of attenuated malaria sporozoites into the capillary (c). Skin illumination with a laser preferably absorbed by hemoglobin causes dilation of the capillary beneath the skin. The extravasated molecules can be sufficiently measured in the skin or guide sporozoites to enter the vessel. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High power laser source for atom cooling based on reliable telecoms technology with all fibre frequency stabilisation

NASA Astrophysics Data System (ADS)

Legg, Thomas; Farries, Mark

2017-02-01

Cold atom interferometers are emerging as important tools for metrology. Designed into gravimeters they can measure extremely small changes in the local gravitational field strength and be used for underground surveying to detect buried utilities, mineshafts and sinkholes prior to civil works. To create a cold atom interferometer narrow linewidth, frequency stabilised lasers are required to cool the atoms and to setup and measure the atom interferometer. These lasers are commonly either GaAs diodes, Ti Sapphire lasers or frequency doubled InGaAsP diodes and fibre lasers. The InGaAsP DFB lasers are attractive because they are very reliable, mass-produced, frequency controlled by injection current and simply amplified to high powers with fibre amplifiers. In this paper a laser system suitable for Rb atom cooling, based on a 1560nm DFB laser and erbium doped fibre amplifier, is described. The laser output is frequency doubled with fibre coupled periodically poled LiNbO3 to a wavelength of 780nm. The output power exceeds 1 W at 780nm. The laser is stabilised at 1560nm against a fibre Bragg resonator that is passively temperature compensated. Frequency tuning over a range of 1 GHz is achieved by locking the laser to sidebands of the resonator that are generated by a phase modulator. This laser design is attractive for field deployable rugged systems because it uses all fibre coupled components with long term proven reliability.

Narrow bandwidth detection of vibration signature using fiber lasers

DOEpatents

Moore, Sean; Soh, Daniel B.S.

2018-05-08

The various technologies presented herein relate to extracting a portion of each pulse in a series of pulses reflected from a target to facilitate determination of a Doppler-shifted frequency for each pulse and, subsequently, a vibration frequency for the series of pulses. Each pulse can have a square-wave configuration, whereby each pulse can be time-gated to facilitate discarding the leading edge and the trailing edge (and associated non-linear effects) of each pulse and accordingly, capture of the central portion of the pulse from which the Doppler-shifted frequency, and ultimately, the vibration frequency of the target can be determined. Determination of the vibration velocity facilitates identification of the target being in a state of motion. The plurality of pulses can be formed from a laser beam (e.g., a continuous wave), the laser beam having a narrow bandwidth.

Cost-effective, transfer-free, flexible resistive random access memory using laser-scribed reduced graphene oxide patterning technology.

PubMed

Tian, He; Chen, Hong-Yu; Ren, Tian-Ling; Li, Cheng; Xue, Qing-Tang; Mohammad, Mohammad Ali; Wu, Can; Yang, Yi; Wong, H-S Philip

2014-06-11

Laser scribing is an attractive reduced graphene oxide (rGO) growth and patterning technology because the process is low-cost, time-efficient, transfer-free, and flexible. Various laser-scribed rGO (LSG) components such as capacitors, gas sensors, and strain sensors have been demonstrated. However, obstacles remain toward practical application of the technology where all the components of a system are fabricated using laser scribing. Memory components, if developed, will substantially broaden the application space of low-cost, flexible electronic systems. For the first time, a low-cost approach to fabricate resistive random access memory (ReRAM) using laser-scribed rGO as the bottom electrode is experimentally demonstrated. The one-step laser scribing technology allows transfer-free rGO synthesis directly on flexible substrates or non-flat substrates. Using this time-efficient laser-scribing technology, the patterning of a memory-array area up to 100 cm(2) can be completed in 25 min. Without requiring the photoresist coating for lithography, the surface of patterned rGO remains as clean as its pristine state. Ag/HfOx/LSG ReRAM using laser-scribing technology is fabricated in this work. Comprehensive electrical characteristics are presented including forming-free behavior, stable switching, reasonable reliability performance and potential for 2-bit storage per memory cell. The results suggest that laser-scribing technology can potentially produce more cost-effective and time-effective rGO-based circuits and systems for practical applications.

Laser-induced fluorescence detection strategies for sodium atoms and compounds in high-pressure combustors

NASA Technical Reports Server (NTRS)

Weiland, Karen J. R.; Wise, Michael L.; Smith, Gregory P.

1993-01-01

A variety of laser-induced fluorescence schemes were examined experimentally in atmospheric pressure flames to determine their use for sodium atom and salt detection in high-pressure, optically thick environments. Collisional energy transfer plays a large role in fluorescence detection. Optimum sensitivity, at the parts in 10 exp 9 level for a single laser pulse, was obtained with the excitation of the 4p-3s transition at 330 nm and the detection of the 3d-3p fluorescence at 818 nm. Fluorescence loss processes, such as ionization and amplified spontaneous emission, were examined. A new laser-induced atomization/laser-induced fluorescence detection technique was demonstrated for NaOH and NaCl. A 248-nm excimer laser photodissociates the salt molecules present in the seeded flames prior to atom detection by laser-induced fluorescence.

OEM fiber laser rangefinder for long-distance measurement

NASA Astrophysics Data System (ADS)

Corman, Alexandre; Chiquet, Frédéric; Avisse, Thomas; Le Flohic, Marc

2015-05-01

SensUp designs and manufactures electro-optical systems based on laser technology, in particular from fiber lasers. Indeed, that kind of source enables us to get a significant peak power with huge repetition rates at the same time, thus combining some characteristics of the two main technologies on the telemetry field today: laser diodes and solid-state lasers. The OEM (Original Equipment Manufacturer) fiber Laser RangeFinder (LRF) set out below, aims to fit the SWaP (Size Weight and Power) requirements of military markets, and might turn out to be a real alternative to other technologies usually used in range finding systems.

A new miniature hand-held solar-blind reagentless standoff chemical, biological, and explosives (CBE) sensor

NASA Astrophysics Data System (ADS)

Hug, W. F.; Reid, R. D.; Bhartia, R.; Lane, A. L.

2008-04-01

Improvised explosive devices (IEDs), vehicle-borne improvised explosive devices (VBIEDs), and suicide bombers are a major threat to many countries and their citizenry. The ability to detect trace levels of these threats with a miniature, hand-held, reagentless, standoff sensor represents a major improvement in the state of the art of CBE surface sensors. Photon Systems, Inc., in collaboration with Jet Propulsion Laboratory, recently demonstrated a new technology hand-held sensor for reagentless, close-range, standoff detection and identification of trace levels CBE materials on surfaces. This targeted ultraviolet CBE (TUCBE) sensor is the result of an Army Phase I STTR program. The resulting 5lb, 5W, flashlight-sized sensor can discriminate CBE from background materials using a combination of deep UV excited resonance Raman (RR) and laser induced native fluorescence (LINF) emissions resulting from excitation by a new technology deep UV laser. Detection and identification is accomplished in less than 1ms. Standoff excitation of suspicious packages, vehicles, persons, and other objects that may contain hazardous materials is accomplished using wavelengths below 250nm where Raman and native fluorescence emissions occupy distinctly different wavelength regions. This enables simultaneous detection of RR and LINF emissions with no interferences. The sensor employs fused RR/LINF chemometric methods to extract the identity of targeted materials from background clutter. Photon Systems has demonstrated detection and identification of 100ng/cm2 of explosives materials at a distance of 1 meter using a sensor with 3.8 cm optical aperture. Expansion of the optical aperture to 38 cm in a lantern-sized sensor will enable similar detection and identification of CBE materials at standoff distances of 10 meters. As a result of excitation and detection in the deep UV and the use of a gated detection system, the sensor is solar blind and can operate in full daylight conditions.

Electro-Optical Laser Technology. Curriculum Utilization. Final Report.

ERIC Educational Resources Information Center

Nawn, John H.

This report describes a program to prepare students for employment as laser technicians and laser operators and to ensure that they have the necessary skills required by the industry. The objectives are to prepare a curriculum and syllabus for an associate degree program in Electro-Optical Laser Technology. The 2-year Electro-Optical Laser program…

Laser marking as environment technology

NASA Astrophysics Data System (ADS)

Sobotova, Lydia; Badida, Miroslav

2017-11-01

The contribution deals with the laser marking as one of the progressive and environment friendly technologies with utilisation in many branches of industry. Engraving and other types of laser marking of different types of materials are very actual technologies these days. Laser marking decreases the waste creation in comparison with the other classical marking technologies, which use paintings or created chips. In this experimental investigation the laser marking surface texturing of material AL99,7 according to STN 42 4003:1993-08 (STN EN 573) has been conducted. The laser marking machine TruMark 6020 and software TruTops Mark were used. Laser surface texturing after laser marking has been realised under different combinations of process parameters: pulse frequency, pulse energy and laser beam scanning speed. The morphological characterization of engraving or annealing surfaces has been performed using scanning electron microscopy (SEM) technique. The evaluation of roughness of engraved surfaces has been realized according to STN EN ISO 4287 by using Surftest SJ 301. The aim of the contribution was to show how different laser parameters affect the surface texture and colour change of metallic materials while creating minimal waste.

Technology Development of a Fiber Optic-Coupled Laser Ignition System for Multi-Combustor Rocket Engines

NASA Technical Reports Server (NTRS)

Trinh, Huu P.; Early, Jim; Osborne, Robin; Thomas, Matthew E.; Bossard, John A.

2002-01-01

This paper addresses the progress of technology development of a laser ignition system at NASA Marshall Space Flight Center (MSFC). The first two years of the project focus on comprehensive assessments and evaluations of a novel dual-pulse laser concept, flight- qualified laser system, and the technology required to integrate the laser ignition system to a rocket chamber. With collaborations of the Department of Energy/Los Alamos National Laboratory (LANL) and CFD Research Corporation (CFDRC), MSFC has conducted 26 hot fire ignition tests with lab-scale laser systems. These tests demonstrate the concept feasibility of dual-pulse laser ignition to initiate gaseous oxygen (GOX)/liquid kerosene (RP-1) combustion in a rocket chamber. Presently, a fiber optic- coupled miniaturized laser ignition prototype is being implemented at the rocket chamber test rig for future testing. Future work is guided by a technology road map that outlines the work required for maturing a laser ignition system. This road map defines activities for the next six years, with the goal of developing a flight-ready laser ignition system.

Embedded Active Fiber Optic Sensing Network for Structural Health Monitoring in Harsh Environments

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

Wang, Anbo

This report summarizes technical progress on the program “Embedded Active Fiber Optic Sensing Network for Structural Health Monitoring in Harsh Environments” funded by the National Energy Technology Laboratory of the U.S. Department of Energy, and performed by the Center for Photonics Technology at Virginia Tech. The objective of this project is to develop a first-of-a-kind technology for remote fiber optic generation and detection of acoustic waves for structural health monitoring in harsh environments. During the project period, which is from April 1, 2013 to Septemeber 30, 2016, three different acoustic generation mechanisms were studied in detail for their applications inmore » building a fiber optic acoustic generation unit (AGU), including laser induced plasma breakdown (LIP), Erbium-doped fiber laser absorption, and metal laser absorption. By comparing the performance of the AGUs designed based on these three mechanisms and analyzing the experimental results with simulations, the metal laser absorption method was selected to build a complete fiber optic structure health monitoring (FO-SHM) system for the proposed high temperature multi-parameter structure health monitoring application. Based on the simulation of elastic wave propagation and fiber Bragg grating acoustic pulse detection, an FO-SHM element together with a completed interrogation system were designed and built. This system was first tested on an aluminum piece in the low-temperature range and successfully demonstrated its capability of multi-parameter monitoring and multi-point sensing. In the later stages of the project, the research was focused on improving the surface attachment design and preparing the FO-SHM element for high temperature environment tests. After several upgrades to the surface attachment methods, the FO-SHM element was able to work reliably up to 600oC when attached to P91 pipes, which are the target material of this project. In the final stage of this project, this FO-SHM sensing system was tested in the simulated harsh environment for its multi-parameter monitoring performance and high-temperature survivability.« less

Recent studies of laser science in paintings conservation and research.

PubMed

Pouli, Paraskevi; Selimis, Alexandros; Georgiou, Savas; Fotakis, Costas

2010-06-15

The removal of aged and deteriorated molecular overlayers from the surface of paintings is a delicate and critical intervention in Cultural Heritage (CH) conservation. This irreversible action gets particularly complicated given the multitude of materials that may be present within a painted work of art (often in ultrathin layers or traces), as well as the exceptional sensitivity of the original surfaces to environmental conditions such as heat, light, and so on. Lasers hold an important role among the available cleaning methodologies, as they enable high control and accuracy, material selectivity, and immediate feedback. Still, prior to their implementation, it is imperative to optimize the cleaning parameters, so to ensure that any potential implications to the remaining materials are minimal and well understood. Toward this aim, research at IESL-FORTH is focused on both refining and continuously updating the laser-cleaning protocols (by introducing novel laser technologies into the field, i.e., ultrashort laser pulses), as well as on investigating and studying the nature and extent of laser-induced physicochemical alterations to the involved materials. In this Account, extended work for the understanding of ultraviolet (UV) laser ablation of polymers is presented. Emphasis is placed on the use of model systems (polymers doped with chromophores of known photochemistry) to examine the in-depth laser-induced modifications at the processed surfaces and thus to illustrate the dependence of their nature and extent on laser parameters and material properties. Furthermore, studies for the potential use of femtosecond UV pulses to overcome certain limitations involved with the nanosecond ablation of molecular overlayers from CH surfaces are highlighted. In particular, it is demonstrated that in the femtosecond regime any chemical modifications are, qualitatively and quantitatively, highly defined, limited and nearly independent of the material properties, such as the absorptivity and the degree of polymerization/molecular weight. Thus, they can be highly potent in the treatment of molecular substrates, enabling new material processing schemes that have not been possible with nanosecond laser technology, as for example, processing of ultrathin varnish layers. Finally, a sensitive indicator is introduced to elucidate the extent of any photochemical or structural modification induced at the substrate on the process of the laser-assisted removal of overpaints. A realistic scenario of an overlayered modern painting is simulated by a sensitive polymer film covered with acrylic paint. The indicator is doped with photosensitizers of known photochemistry and strong fluorescence emission, which allow the employment of laser induced fluorescence (LIF) for the detection of any chemical modifications generated into the substrate during laser cleaning. In addition, nonlinear microscopy techniques are successfully employed to examine the extent of these modifications. The suggested methodology is proven to reliably and accurately detect potential changes, and thus, it can serve as a monitoring tool to fine-tune the cleaning protocol and safeguard the original painting.

Application of mass spectrometry technologies for the discovery of low-molecular weight modulators of enzymes and protein-protein interactions.

PubMed

Zehender, Hartmut; Mayr, Lorenz M

2007-10-01

In recent years, mass spectrometry has gained widespread use as an assay and screening technology in drug discovery because it enables sensitive, label-free detection of low-molecular weight modulators of biomolecules as well as sensitive and accurate detection of high-molecular weight modifications of biomolecules. Electrospray and matrix-assisted laser desorption ionization are the most widely used ionization techniques to identify chemical compounds interfering with enzymatic function, receptor-ligand binding or molecules modulating a protein-protein interaction of interest. Mass spectrometry based techniques are no longer restricted to screening in biochemical assay systems but have now become also applicable to imaging of biomolecules and chemical compounds in cell-based assay systems and even in highly complex tissue sections.

A Little Sensor That Packs a Wallop

NASA Technical Reports Server (NTRS)

2000-01-01

A gas sensor originally built for NASA to measure the composition of the atmosphere of Earth and Mars has been commercialized by SpectraSensors. The commercial tunable diode laser (TDL) gas sensor can be used for oil and gas pipeline monitoring, aircraft safety, environmental monitoring and medicine. The TDL technology is good at detecting low levels of gases from parts-per-million to parts-per-billion.

Sub-200 femtosecond dispersion-managed soliton ytterbium-doped fiber laser based on carbon nanotubes saturable absorber.

PubMed

Hou, Lei; Guo, Hongyu; Wang, Yonggang; Sun, Jiang; Lin, Qimeng; Bai, Yang; Bai, Jintao

2018-04-02

Ultrafast fiber laser light sources attract enormous interest due to the booming applications they are enabling, including long-distance communication, optical metrology, detecting technology of infra-biophotons, and novel material processing. In this paper, we demonstrate 175 fs dispersion-managed soliton (DMS) mode-locked ytterbium-doped fiber (YDF) laser based on single-walled carbon nanotubes (SWCNTs) saturable absorber (SA). The output DMSs have been achieved with repetition rate of 21.2 MHz, center wavelength of 1025.5 nm, and a spectral width of 32.7 nm. The operation directly pulse duration of 300 fs for generated pulse is the reported shortest pulse width for broadband SA based YDF lasers. By using an external grating-based compressor, the pulse duration could be compressed down to 175 fs. To the best of our knowledge, it is the shortest pulse duration obtained directly from YDF laser based on broadband SAs. In this paper, SWCNTs-SA has been utilized as the key optical component (mode locker) and the grating pair providing negative dispersion acts as the dispersion controller.

Next generation DIRCM for 2.1-2.3 micron wavelength based on direct-diode GaSb technology

NASA Astrophysics Data System (ADS)

Dvinelis, Edgaras; Naujokaitė, Greta; Greibus, Mindaugas; Trinkūnas, Augustinas; Vizbaras, Kristijonas; Vizbaras, Augustinas

2018-02-01

Continuous advances in low-cost MANPAD heat-seeking missile technology over the past 50 years remains the number one hostile threat to airborne platforms globally responsible for over 60 % of casualties. Laser based directional countermeasure (DIRCM) technology have been deployed to counter the threat. Ideally, a laser based DIRCM system must involve a number of lasers emitting at different spectral bands mimicking the spectral signature of the airborne platform. Up to now, near and mid infrared spectral bands have been covered with semiconductor laser technology and only SWIR band remained with bulky fiber laser technology. Recent technology developments on direct-diode GaSb laser technology at Brolis Semiconductors offer a replacement for the fiber laser source leading to significant improvements by few orders of magnitude in weight, footprint, efficiency and cost. We demonstrate that with careful engineering, several multimode emitters can be combined to provide a directional laser beam with radiant intensity from 10 kW/sr to 60 kW/sr in an ultra-compact hermetic package with weight < 30 g and overall efficiency of 15 % in the 2.1- 2.3 micron spectral band offering 150 times improvement in efficiency and reduction in footprint. We will discuss present results, challenges and future developments for such next-generation integrated direct diode DIRCM modules for SWIR band.

Scanning, standoff TDLAS leak imaging and quantification

NASA Astrophysics Data System (ADS)

Wainner, Richard T.; Aubut, Nicholas F.; Laderer, Matthew C.; Frish, Michael B.

2017-05-01

This paper reports a novel quantitative gas plume imaging tool, based on active near-infrared Backscatter Tunable Diode Laser Absorption Spectroscopy (b-TDLAS) technology, designed for upstream natural gas leak applications. The new tool integrates low-cost laser sensors with video cameras to create a highly sensitive gas plume imager that also quantifies emission rate, all in a lightweight handheld ergonomic package. It is intended to serve as a lower-cost, higherperformance, enhanced functionality replacement for traditional passive non-quantitative mid-infrared Optical Gas Imagers (OGI) which are utilized by industry to comply with natural gas infrastructure Leak Detection and Repair (LDAR) requirements. It addresses the need for reliable, robust, low-cost sensors to detect and image methane leaks, and to quantify leak emission rates, focusing on inspections of upstream oil and gas operations, such as well pads, compressors, and gas plants. It provides: 1) Colorized quantified images of path-integrated methane concentration. The images depict methane plumes (otherwise invisible to the eye) actively interrogated by the laser beam overlaid on a visible camera image of the background. The detection sensitivity exceeds passive OGI, thus simplifying the manual task of leak detection and location; and 2) Data and algorithms for using the quantitative information gathered by the active detection technique to deduce plume flux (i.e. methane emission rate). This key capability will enable operators to prioritize leak repairs and thereby minimize the value of lost product, as well as to quantify and minimize greenhouse gas emissions, using a tool that meets EPA LDAR imaging equipment requirements.

One Micron Laser Technology Advancements at GSFC

NASA Technical Reports Server (NTRS)

Heaps, William S.

2010-01-01

This slide presentation reviews the advancements made in one micron laser technology at Goddard Space Flight Center. It includes information about risk factors that are being addressed by GSFC, and overviews of the various programs that GSFC is currently managing that are using 1 micron laser technology.

Laser shock wave and its applications

NASA Astrophysics Data System (ADS)

Yang, Chaojun; Zhang, Yongkang; Zhou, Jianzhong; Zhang, Fang; Feng, Aixin

2007-12-01

The technology of laser shock wave is used to not only surface modification but also metal forming. It can be divided into three parts: laser shock processing, laser shock forming (LSF) and laser peenforming(LPF). Laser shock processing as a surface treatment to metals can make engineering components have a residual compressive stress so that it obviously improves their fatigue strength and stress corrosion performances, while laser shock forming (LSF) is a novel technique that is used in plastic deformation of sheet metal recently and Laser peen forming (LPF) is another new sheet metal forming process presented in recent years. They all can be carried out by a high-power and repetition pulse Nd:Glass laser device made by Jiangsu University. Laser shock technology has characterized of ultrahigh pressure and high strain rate (10 6 - 10 7s -1). Now, for different materials, we are able to form different metals to contours and shapes and simultaneity leave their surfaces in crack-resistant compressive stress state. The results show that the technology of laser shock wave can strengthen surface property and prolong fatigue life and especially can deform metals to shapes that could not be adequately made using conventional methods. With the development of the technology of laser shock wave, the applied fields of laser will become greater and greater.

Advanced shortwave infrared and Raman hyperspectral sensors for homeland security and law enforcement operations

NASA Astrophysics Data System (ADS)

Klueva, Oksana; Nelson, Matthew P.; Gardner, Charles W.; Gomer, Nathaniel R.

2015-05-01

Proliferation of chemical and explosive threats as well as illicit drugs continues to be an escalating danger to civilian and military personnel. Conventional means of detecting and identifying hazardous materials often require the use of reagents and/or physical sampling, which is a time-consuming, costly and often dangerous process. Stand-off detection allows the operator to detect threat residues from a safer distance minimizing danger to people and equipment. Current fielded technologies for standoff detection of chemical and explosive threats are challenged by low area search rates, poor targeting efficiency, lack of sensitivity and specificity or use of costly and potentially unsafe equipment such as lasers. A demand exists for stand-off systems that are fast, safe, reliable and user-friendly. To address this need, ChemImage Sensor Systems™ (CISS) has developed reagent-less, non-contact, non-destructive sensors for the real-time detection of hazardous materials based on widefield shortwave infrared (SWIR) and Raman hyperspectral imaging (HSI). Hyperspectral imaging enables automated target detection displayed in the form of image making result analysis intuitive and user-friendly. Application of the CISS' SWIR-HSI and Raman sensing technologies to Homeland Security and Law Enforcement for standoff detection of homemade explosives and illicit drugs and their precursors in vehicle and personnel checkpoints is discussed. Sensing technologies include a portable, robot-mounted and standalone variants of the technology. Test data is shown that supports the use of SWIR and Raman HSI for explosive and drug screening at checkpoints as well as screening for explosives and drugs at suspected clandestine manufacturing facilities.

Self-Calibration and Laser Energy Monitor Validations for a Double-Pulsed 2-Micron CO2 Integrated Path Differential Absorption Lidar Application

NASA Technical Reports Server (NTRS)

Refaat, Tamer F.; Singh, Upendra N.; Petros, Mulugeta; Remus, Ruben; Yu, Jirong

2015-01-01

Double-pulsed 2-micron integrated path differential absorption (IPDA) lidar is well suited for atmospheric CO2 remote sensing. The IPDA lidar technique relies on wavelength differentiation between strong and weak absorbing features of the gas normalized to the transmitted energy. In the double-pulse case, each shot of the transmitter produces two successive laser pulses separated by a short interval. Calibration of the transmitted pulse energies is required for accurate CO2 measurement. Design and calibration of a 2-micron double-pulse laser energy monitor is presented. The design is based on an InGaAs pin quantum detector. A high-speed photo-electromagnetic quantum detector was used for laser-pulse profile verification. Both quantum detectors were calibrated using a reference pyroelectric thermal detector. Calibration included comparing the three detection technologies in the single-pulsed mode, then comparing the quantum detectors in the double-pulsed mode. In addition, a self-calibration feature of the 2-micron IPDA lidar is presented. This feature allows one to monitor the transmitted laser energy, through residual scattering, with a single detection channel. This reduces the CO2 measurement uncertainty. IPDA lidar ground validation for CO2 measurement is presented for both calibrated energy monitor and self-calibration options. The calibrated energy monitor resulted in a lower CO2 measurement bias, while self-calibration resulted in a better CO2 temporal profiling when compared to the in situ sensor.

Neuroscience imaging enabled by new highly tunable and high peak power femtosecond lasers

NASA Astrophysics Data System (ADS)

Hakulinen, T.; Klein, J.

2017-02-01

Neuroscience applications benefit from recent developments in industrial femtosecond laser technology. New laser sources provide several megawatts of peak power at wavelength of 1040 nm, which enables simultaneous optogenetics photoactivation of tens or even hundreds of neurons using red shifted opsins. Another recent imaging trend is to move towards longer wavelengths, which would enable access to deeper layers of tissue due to lower scattering and lower absorption in the tissue. Femtosecond lasers pumping a non-collinear optical parametric amplifier (NOPA) enable the access to longer wavelengths with high peak powers. High peak powers of >10 MW at 1300 nm and 1700 nm allow effective 3-photon excitation of green and red shifted calcium indicators respectively and access to deeper, sub-cortex layers of the brain. Early results include in vivo detection of spontaneous activity in hippocampus within an intact mouse brain, where neurons express GCaMP6 activated in a 3-photon process at 1320 nm.

Targeted Multiplex Imaging Mass Spectrometry in Transmission Geometry for Subcellular Spatial Resolution

PubMed Central

Lavenant, Gwendoline Thiery; Zavalin, Andrey I.; Caprioli, Richard M.

2013-01-01

Targeted multiplex Imaging Mass Spectrometry utilizes several different antigen-specific primary antibodies, each directly labeled with a unique photocleavable mass tag, to detect multiple antigens in a single tissue section. Each photocleavable mass tag bound to an antibody has a unique molecular weight and can be readily ionized by laser desorption ionization mass spectrometry. This manuscript describes a mass spectrometry method that allows imaging of targeted single cells within tissue using transmission geometry laser desorption ionization mass spectrometry. Transmission geometry focuses the laser beam on the back side of the tissue placed on a glass slide, providing a 2 μm diameter laser spot irradiating the biological specimen. This matrix-free method enables simultaneous localization at the sub-cellular level of multiple antigens using specific tagged antibodies. We have used this technology to visualize the co-expression of synaptophysin and two major hormones peptides, insulin and somatostatin, in duplex assays in beta and delta cells contained in a human pancreatic islet. PMID:23397138

Joint analyses by laser-induced breakdown spectroscopy (LIBS) and Raman spectroscopy at stand-off distances.

PubMed

Wiens, Roger C; Sharma, Shiv K; Thompson, Justin; Misra, Anupam; Lucey, Paul G

2005-08-01

Raman spectroscopy and laser-induced breakdown spectroscopy (LIBS) of solid samples have both been shown to be feasible with sample-to-instrument distances of many meters. The two techniques are very useful together, as the combination of elemental compositions from LIBS and molecular vibrational information from Raman spectroscopy strongly complement each other. Remote LIBS and Raman spectroscopy spectra were taken together on a number of mineral samples including sulfates, carbonates and silicates at a distance of 8.3 m. The complementary nature of these spectra is highlighted and discussed. A factor of approximately 20 difference in intensity was observed between the brightest Raman line of calcite, at optimal laser power, and the brighter Ca I LIBS emission line measured with 55 mJ/pulse laser power. LIBS and Raman spectroscopy have several obstacles to devising a single instrument capable of both techniques. These include the differing spectral ranges and required detection sensitivity. The current state of technology in these areas is discussed.

Research on effect of rough surface on FMCW laser radar range accuracy

NASA Astrophysics Data System (ADS)

Tao, Huirong

2018-03-01

The non-cooperative targets large scale measurement system based on frequency-modulated continuous-wave (FMCW) laser detection and ranging technology has broad application prospects. It is easy to automate measurement without cooperative targets. However, the complexity and diversity of the surface characteristics of the measured surface directly affects the measurement accuracy. First, the theoretical analysis of range accuracy for a FMCW laser radar was studied, the relationship between surface reflectivity and accuracy was obtained. Then, to verify the effect of surface reflectance for ranging accuracy, a standard tool ball and three standard roughness samples were measured within 7 m to 24 m. The uncertainty of each target was obtained. The results show that the measurement accuracy is found to increase as the surface reflectivity gets larger. Good agreements were obtained between theoretical analysis and measurements from rough surfaces. Otherwise, when the laser spot diameter is smaller than the surface correlation length, a multi-point averaged measurement can reduce the measurement uncertainty. The experimental results show that this method is feasible.

Targeted Multiplex Imaging Mass Spectrometry in Transmission Geometry for Subcellular Spatial Resolution

NASA Astrophysics Data System (ADS)

Thiery-Lavenant, Gwendoline; Zavalin, Andre I.; Caprioli, Richard M.

2013-04-01

Targeted multiplex imaging mass spectrometry utilizes several different antigen-specific primary antibodies, each directly labeled with a unique photocleavable mass tag, to detect multiple antigens in a single tissue section. Each photocleavable mass tag bound to an antibody has a unique molecular weight and can be readily ionized by laser desorption ionization mass spectrometry. This article describes a mass spectrometry method that allows imaging of targeted single cells within tissue using transmission geometry laser desorption ionization mass spectrometry. Transmission geometry focuses the laser beam on the back side of the tissue placed on a glass slide, providing a 2 μm diameter laser spot irradiating the biological specimen. This matrix-free method enables simultaneous localization at the sub-cellular level of multiple antigens using specific tagged antibodies. We have used this technology to visualize the co-expression of synaptophysin and two major hormones peptides, insulin and somatostatin, in duplex assays in beta and delta cells contained in a human pancreatic islet.

Laser Metal Deposition as Repair Technology for a Gas Turbine Burner Made of Inconel 718

NASA Astrophysics Data System (ADS)

Petrat, Torsten; Graf, Benjamin; Gumenyuk, Andrey; Rethmeier, Michael

Maintenance, repair and overhaul of components are of increasing interest for parts of high complexity and expensive manufacturing costs. In this paper a production process for laser metal deposition is presented, and used to repair a gas turbine burner of Inconel 718. Different parameters for defined track geometries were determined to attain a near net shape deposition with consistent build-up rate for changing wall thicknesses over the manufacturing process. Spot diameter, powder feed rate, welding velocity and laser power were changed as main parameters for a different track size. An optimal overlap rate for a constant layer height was used to calculate the best track size for a fitting layer width similar to the part dimension. Deviations in width and height over the whole build-up process were detected and customized build-up strategies for the 3D sequences were designed. The results show the possibility of a near net shape repair by using different track geometries with laser metal deposition.

Safe laser application requires more than laser safety

NASA Astrophysics Data System (ADS)

Frevel, A.; Steffensen, B.; Vassie, L.

1995-02-01

An overview is presented concerning aspects of laser safety in European industrial laser use. Surveys indicate that there is a large variation in the safety strategies amongst industrial laser users. Some key problem areas are highlighted. Emission of hazardous substances is a major problem for users of laser material processing systems where the majority of the particulate is of a sub-micrometre size, presenting a respiratory hazard. Studies show that in many cases emissions are not frequently monitored in factories and uncertainty exists over the hazards. Operators of laser machines do not receive adequate job training or safety training. The problem is compounded by a plethora of regulations and standards which are difficult to interpret and implement, and inspectors who are not conversant with the technology or the issues. A case is demonstrated for a more integrated approach to laser safety, taking into account the development of laser applications, organizational and personnel development, in addition to environmental and occupational health and safety aspects. It is necessary to achieve a harmonization between these elements in any organization involved in laser technology. This might be achieved through establishing technology transfer centres in laser technology.

Nitinol laser cutting: microstructure and functional properties of femtosecond and continuous wave laser processing

NASA Astrophysics Data System (ADS)

Biffi, C. A.; Tuissi, A.

2017-03-01

Thermal processing can affect the properties of smart materials, and the correct selection of the best manufacturing technology is fundamental for producing high tech smart devices, containing embedded functional properties. In this work cutting of thin superelastic Nitinol plates using a femtosecond (fs) and continuous wave (CW) laser was studied. Diamond shaped elements were cut to characterize the kerf qualitative features; microstructural analysis of the cross sections allowed identification of thermal damage characteristics introduced into the material during the laser processes. A thermally undamaged microstructure was observed for fs laser cutting, while CW was seen to be characterized by a large heat-affected zone. Functional properties were investigated by differential scanning calorimetry and tensile testing of laser cut microelements and of the reference material. It was seen that the martensitic transformation behavior of Nitinol is not affected by fs regime, while cw cutting provokes an effect equivalent to a high temperature thermal treatment in the material surrounding the cutting kerf, degradating the material properties. Finally, tensile testing indicated that superelastic performances were guaranteed by fs regime, while strong reduction of the recoverable strain was detected in the CW processed sample.

Towards novel compact laser sources for non-invasive diagnostics and treatment

NASA Astrophysics Data System (ADS)

Rafailov, Edik U.; Litvinova, Karina S.; Sokolovski, Sergei G.

2015-08-01

An important field of application of lasers is biomedical optics. Here, they offer great utility for diagnosis, therapy and surgery. For the development of novel methods of laser-based biomedical diagnostics careful study of light propagation in biological tissues is necessary to enhance our understanding of the optical measurements undertaken, increase research and development capacity and the diagnostic reliability of optical technologies. Ultimately, fulfilling these requirements will increase uptake in clinical applications of laser based diagnostics and therapeutics. To address these challenges informative biomarkers relevant to the biological and physiological function or disease state of the organism must be selected. These indicators are the results of the analysis of tissues and cells, such as blood. For non-invasive diagnostics peripheral blood, cells and tissue can potentially provide comprehensive information on the condition of the human organism. A detailed study of the light scattering and absorption characteristics can quickly detect physiological and morphological changes in the cells due to thermal, chemical, antibiotic treatments, etc [1-5]. The selection of a laser source to study the structure of biological particles also benefits from the fact that gross pathological changes are not induced and diagnostics make effective use of the monochromatic directional coherence properties of laser radiation.

[Study on Ammonia Emission Rules in a Dairy Feedlot Based on Laser Spectroscopy Detection Method].

PubMed

He, Ying; Zhang, Yu-jun; You, Kun; Wang, Li-ming; Gao, Yan-wei; Xu, Jin-feng; Gao, Zhi-ling; Ma, Wen-qi

2016-03-01

It needs on-line monitoring of ammonia concentration on dairy feedlot to disclose ammonia emissions characteristics accurately for reducing ammonia emissions and improving the ecological environment. The on-line monitoring system for ammonia concentration has been designed based on Tunable Diode Laser Absorption Spectroscopy (TDLAS) technology combining with long open-path technology, then the study has been carried out with inverse dispersion technique and the system. The ammonia concentration in-situ has been detected and ammonia emission rules have been analyzed on a dairy feedlot in Baoding in autumn and winter of 2013. The monitoring indicated that the peak of ammonia concentration was 6.11 x 10(-6) in autumn, and that was 6.56 x 10(-6) in winter. The concentration results show that the variation of ammonia concentration had an obvious diurnal periodicity, and the general characteristic of diurnal variation was that the concentration was low in the daytime and was high at night. The ammonia emissions characteristic was obtained with inverse dispersion model that the peak of ammonia emissions velocity appeared at noon. The emission velocity was from 1.48 kg/head/hr to 130.6 kg/head/hr in autumn, and it was from 0.004 5 kg/head/hr to 43.32 kg/head/hr in winter which was lower than that in autumn. The results demonstrated ammonia emissions had certain seasonal differences in dairy feedlot scale. In conclusion, the ammonia concentration was detected with optical technology, and the ammonia emissions results were acquired by inverse dispersion model analysis with large range, high sensitivity, quick response without gas sampling. Thus, it's an effective method for ammonia emissions monitoring in dairy feedlot that provides technical support for scientific breeding.

Laser Experiments with ARTEMIS Satellite in Cloudy Conditions

NASA Astrophysics Data System (ADS)

Kuzkov, Volodymyr; Sodnik, Zoran; Kuzkov, Sergii; Caramia, Vincenzo

2014-05-01

In July 2001, the ARTEMIS satellite with laser communication terminal OPALE on board was launched. 1789 laser communications sessions were performed between ARTEMIS and SPOT-4 (PASTEL) from 01 April 2003 to 09 January 2008 with total duration of 378 hours. In addition ESA's Optical Ground Station (OGS) performed laser communication experiments with OPALE in various atmospheric conditions. Since the launch of ARTEMIS, the amount of information handled by geostationary telecommunication satellites has increased dramatically and so has the demand for data rate that needs to be transmitted from ground. With limited bandwidth allocations in the radio frequency bands interest has grown for laser communication feeder link technology. In this respect there is interest to compare the influence of atmosphere conditions in different atmospheric regions with respect to laser transmission. Two locations are being compared, namely ESA's OGS (located in an altitude of 2400 m above sea level) and the Main Astronomical Observatory of Ukraine (MAO) (located at an altitude of 190 m above sea level). In 2002 MAO started the development of a ground laser communication system for the AZT-2 telescope. The MAO developed compact laser communication system is called LACES (Laser Atmosphere and Communication Experiments with Satellites) [1] and the work was supported by the National Space Agency of Ukraine and by ESA. The beacon laser from OPALE was occasionally detected even in cloudy conditions and an anomalous atmospheric refraction at low elevation angles was observed. The main results of laser experiments with ARTEMIS through clouds are presented in the paper.

Photonic sensors review recent progress of fiber sensing technologies in Tianjin University

NASA Astrophysics Data System (ADS)

Liu, Tiegen; Liu, Kun; Jiang, Junfeng; Li, Enbang; Zhang, Hongxia; Jia, Dagong; Zhang, Yimo

2011-03-01

The up to date progress of fiber sensing technologies in Tianjin University are proposed in this paper. Fiber-optic temperature sensor based on the interference of selective higher-order modes in circular optical fiber is developed. Parallel demodulation for extrinsic Fabry-Perot interferometer (EFPI) and fiber Bragg grating (FBG) sensors is realized based on white light interference. Gas concentration detection is realized based on intra-cavity fiber laser spectroscopy. Polarization maintaining fiber (PMF) is used for distributed position or displacement sensing. Based on the before work and results, we gained National Basic Research Program of China on optical fiber sensing technology and will develop further investigation in this area.

LASERUT® Technology Development Programs for the Ultrasonic Inspection of Composites in the Aerospace Industry

NASA Astrophysics Data System (ADS)

Dubois, Marc; Drake, Thomas; Osterkamp, Mark; Yawn, Ken; Kaiser, David; Do, Tho; Maestas, Jeff; Thomas, Michael

2008-02-01

A laser-ultrasonic technique developed at Lockheed Martin Aeronautics called LaserUT® is used for the ultrasonic inspection of composite parts in the aeronautic industry and has demonstrated significant reduction in inspection labor and capital expenditure over approximately 20,000 parts so far. Development of new technologies will further increase LaserUT savings: structured-light mapping, improved CO2 laser, mid-infrared generation laser, and new robotic approach. Those different technologies are described and their status relatively to their introduction to production is discussed.

Detection of Progressive Retinal Nerve Fiber Layer Loss in Glaucoma Using Scanning Laser Polarimetry with Variable Corneal Compensation

PubMed Central

Medeiros, Felipe A.; Alencar, Luciana M.; Zangwill, Linda M.; Bowd, Christopher; Vizzeri, Gianmarco; Sample, Pamela A.; Weinreb, Robert N.

2010-01-01

Purpose To evaluate the ability of scanning laser polarimetry with variable corneal compensation to detect progressive retinal nerve fiber layer (RNFL) loss in glaucoma patients and patients suspected of having the disease. Methods This was an observational cohort study that included 335 eyes of 195 patients. Images were obtained annually with the GDx VCC scanning laser polarimeter, along with optic disc stereophotographs and standard automated perimetry (SAP) visual fields. The median follow-up time was 3.94 years. Progression was determined using commercial software for SAP and by masked assessment of optic disc stereophotographs performed by expert graders. Random coefficient models were used to evaluate the relationship between RNFL thickness measurements over time and progression as determined by SAP and/or stereophotographs. Results From the 335 eyes, 34 (10%) showed progression over time by stereophotographs and/or SAP. Average GDx VCC measurements decreased significantly over time for both progressors as well as non-progressors. However, the rate of decline was significantly higher in the progressing group (−0.70 μm/year) compared to the non-progressing group (−0.14 μm/year; P = 0.001). Black race and male sex were significantly associated with higher rates of RNFL loss during follow-up. Conclusions The GDx VCC scanning laser polarimeter was able to identify longitudinal RNFL loss in eyes that showed progression in optic disc stereophotographs and/or visual fields. These findings suggest that this technology could be useful to detect and monitor progressive disease in patients with established diagnosis of glaucoma or suspected of having the disease. PMID:19029038

A feasibility study of damage detection in beams using high-speed camera (Conference Presentation)

NASA Astrophysics Data System (ADS)

Wan, Chao; Yuan, Fuh-Gwo

2017-04-01

In this paper a method for damage detection in beam structures using high-speed camera is presented. Traditional methods of damage detection in structures typically involve contact (i.e., piezoelectric sensor or accelerometer) or non-contact sensors (i.e., laser vibrometer) which can be costly and time consuming to inspect an entire structure. With the popularity of the digital camera and the development of computer vision technology, video cameras offer a viable capability of measurement including higher spatial resolution, remote sensing and low-cost. In the study, a damage detection method based on the high-speed camera was proposed. The system setup comprises a high-speed camera and a line-laser which can capture the out-of-plane displacement of a cantilever beam. The cantilever beam with an artificial crack was excited and the vibration process was recorded by the camera. A methodology called motion magnification, which can amplify subtle motions in a video is used for modal identification of the beam. A finite element model was used for validation of the proposed method. Suggestions for applications of this methodology and challenges in future work will be discussed.

New Class of Excimer-Pumped Atomic Lasers (XPALS)

DTIC Science & Technology

2017-01-27

quantum efficiency greater thnn one, has been demonstrated. We believe this laser to represent a breakthrough in laser technology because the system...navy.mil Prepared by J. G. Eden and A. E. Mironov Laboratory For Optical Physics and Engineering Department of Electrical and Computer Engineering...viability of an atomic laser having a quantum efficiency greater than one. We believe this laser to represent a breakthrough in laser technology

SU-F-J-44: Development of a Room Laser Based Real-Time Alignment Monitoring System Using An Array of Photodiodes

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

Noh, Y; Kim, T; Kang, S

2016-06-15

Purpose: To develop a real-time alignment monitoring system (RAMS) to compensate for the limitations of the conventional room laser based alignment system, and to verify the feasibility of the RAMS. Methods: The RAMS was composed of a room laser sensing array (RLSA), an analog-todigital converter, and a control PC. In the RLSA, seven photodiodes (each in 1 mm width) are arranged in a pattern that the RAMS provides alignment in 1 mm resolution. It works based on detecting laser light aligned on one of photodiodes. When misaligned, the laser would match with different photodiode(s) giving signal at unexpected location. Thus,more » how much displaced can be determined. To verify the reproducibility of the system with respect to time as well as repeated set-ups, temporal reproducibility and repeatability test was conducted. The accuracy of the system was tested by obtaining detection signals with varying laser-match positions. Results: The signal of the RAMS was found to be stable with respect to time. The repeatability test resulted in a maximum coefficient of variance of 1.14%, suggesting that the signal of the RAMS was stable over repeated set-ups. In the accuracy test, signals between when the laser was aligned and notaligned with any of sensors could be distinguished by signal intensity. The signals of not-aligned sensors were always below 75% of the signal of the aligned sensor. It was confirmed that the system could detect 1 mm of movement by monitoring the pattern of signals, and could observe the movement of the system in real-time. Conclusion: We developed a room laser based alignment monitoring system. The feasibility test verified that the system is capable of quantitative alignment monitoring in real time. The system is relatively simple, not expensive, and considered to be easily incorporated into conventional room laser systems for real-time alignment monitoring. This research was supported by the Mid-career Researcher Program through NRF funded by the Ministry of Science, ICT & Future Planning of Korea (NRF-2014R1A2A1A10050270) and by the Radiation Technology R&D program through the National Research Foundation of Korea funded by the Ministry of Science, ICT & Future Planning (No. 2013M2A2A7038291)« less

High-energy laser weapons: technology overview

NASA Astrophysics Data System (ADS)

Perram, Glen P.; Marciniak, Michael A.; Goda, Matthew

2004-09-01

High energy laser (HEL) weapons are ready for some of today"s most challenging military applications. For example, the Airborne Laser (ABL) program is designed to defend against Theater Ballistic Missiles in a tactical war scenario. Similarly, the Tactical High Energy Laser (THEL) program is currently testing a laser to defend against rockets and other tactical weapons. The Space Based Laser (SBL), Advanced Tactical Laser (ATL) and Large Aircraft Infrared Countermeasures (LAIRCM) programs promise even greater applications for laser weapons. This technology overview addresses both strategic and tactical roles for HEL weapons on the modern battlefield and examines current technology limited performance of weapon systems components, including various laser device types, beam control systems, atmospheric propagation, and target lethality issues. The characteristics, history, basic hardware, and fundamental performance of chemical lasers, solid state lasers and free electron lasers are summarized and compared. The elements of beam control, including the primary aperture, fast steering mirror, deformable mirrors, wavefront sensors, beacons and illuminators will be discussed with an emphasis on typical and required performance parameters. The effects of diffraction, atmospheric absorption, scattering, turbulence and thermal blooming phenomenon on irradiance at the target are described. Finally, lethality criteria and measures of weapon effectiveness are addressed. The primary purpose of the presentation is to define terminology, establish key performance parameters, and summarize technology capabilities.

Vacuum decay container closure integrity leak test method development and validation for a lyophilized product-package system.

PubMed

Patel, Jayshree; Mulhall, Brian; Wolf, Heinz; Klohr, Steven; Guazzo, Dana Morton

2011-01-01

A leak test performed according to ASTM F2338-09 Standard Test Method for Nondestructive Detection of Leaks in Packages by Vacuum Decay Method was developed and validated for container-closure integrity verification of a lyophilized product in a parenteral vial package system. This nondestructive leak test method is intended for use in manufacturing as an in-process package integrity check, and for testing product stored on stability in lieu of sterility tests. Method development and optimization challenge studies incorporated artificially defective packages representing a range of glass vial wall and sealing surface defects, as well as various elastomeric stopper defects. Method validation required 3 days of random-order replicate testing of a test sample population of negative-control, no-defect packages and positive-control, with-defect packages. Positive-control packages were prepared using vials each with a single hole laser-drilled through the glass vial wall. Hole creation and hole size certification was performed by Lenox Laser. Validation study results successfully demonstrated the vacuum decay leak test method's ability to accurately and reliably detect those packages with laser-drilled holes greater than or equal to approximately 5 μm in nominal diameter. All development and validation studies were performed at Whitehouse Analytical Laboratories in Whitehouse, NJ, under the direction of consultant Dana Guazzo of RxPax, LLC, using a VeriPac 455 Micro Leak Test System by Packaging Technologies & Inspection (Tuckahoe, NY). Bristol Myers Squibb (New Brunswick, NJ) fully subsidized all work. A leak test performed according to ASTM F2338-09 Standard Test Method for Nondestructive Detection of Leaks in Packages by Vacuum Decay Method was developed and validated to detect defects in stoppered vial packages containing lyophilized product for injection. This nondestructive leak test method is intended for use in manufacturing as an in-process package integrity check, and for testing product stored on stability in lieu of sterility tests. Test method validation study results proved the method capable of detecting holes laser-drilled through the glass vial wall greater than or equal to 5 μm in nominal diameter. Total test time is less than 1 min per package. All method development and validation studies were performed at Whitehouse Analytical Laboratories in Whitehouse, NJ, under the direction of consultant Dana Guazzo of RxPax, LLC, using a VeriPac 455 Micro Leak Test System by Packaging Technologies & Inspection (Tuckahoe, NY). Bristol Myers Squibb (New Brunswick, NJ) fully subsidized all work.

Lasers and radiofrequency devices in dentistry.

PubMed

Green, James; Weiss, Adam; Stern, Avichai

2011-07-01

Advances in technology are changing the ways that patients experience dental treatment. Technology helps to decrease treatment time and makes the treatment more comfortable for the patient. One technological advance is the use of lasers in dentistry. Lasers are providing more efficient, more comfortable, and more predictable outcomes for patients. Lasers are used in all aspects of dentistry, including operative, periodontal, endodontic, orthodontic, and oral and maxillofacial surgery. Lasers are used for soft and hard tissue procedures in the treatment of pathologic conditions and for esthetic procedures. This article discusses how lasers work and their application in the various specialties within dentistry. Copyright © 2011 Elsevier Inc. All rights reserved.

Toward robot-assisted neurosurgical lasers.

PubMed

Motkoski, Jason W; Yang, Fang Wei; Lwu, Shelly H H; Sutherland, Garnette R

2013-04-01

Despite the potential increase in precision and accuracy, laser technology is not widely used in neurological surgery. This in part relates to challenges associated with the early introduction of lasers into neurosurgery. Considerable advances in laser technology have occurred, which together with robotic technology could create an ideal platform for neurosurgical application. In this study, a 980-nm contact diode laser was integrated with neuroArm. Preclinical evaluation involved partial hepatectomy, bilateral nephrectomy, splenectomy, and bilateral submandibular gland excision in a Sprague-Dawley rat model (n = 50). Total surgical time, blood loss as weight of surgical gauze before and after the procedure, and the incidence of thermal, vascular, or lethal injury were recorded and converted to an overall performance score. Thermal damage was evaluated in the liver using tissue samples stained with hematoxylin and eosin. Clinical studies involved step-wise integration of the 980-nm laser system into four neurosurgical cases. Results demonstrate the successful integration of contact laser technology into microsurgery, with and without robotic assistance. In preclinical studies, the laser improved microsurgical performance and reduced thermal damage, while neuroArm decreased intra- and intersurgeon variability. Clinical studies demonstrate dutility in meningioma resection (n = 4). Together, laser and robotic technology offered a more consistent, expedient, and precise tool for microsurgery.

Laser Science & Technology Program Annual Report - 2000

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

Chen, H-L

2001-03-20

The Laser Science and Technology (LS&T) Program Annual Report 2001 provides documentation of the achievements of the LLNL LS&T Program during the April 2001 to March 2002 period using three formats: (1) an Overview that is a narrative summary of important results for the year; (2) brief summaries of research and development activity highlights within the four Program elements: Advanced Lasers and Components (AL&C), Laser Optics and Materials (LO&M), Short Pulse Laser Applications and Technologies (SPLAT), and High-Energy Laser System and Tests (HELST); and (3) a compilation of selected articles and technical reports published in reputable scientific or technology journalsmore » in this period. All three elements (Annual Overview, Activity Highlights, and Technical Reports) are also on the Web: http://laser.llnl.gov/lasers/pubs/icfq.html. The underlying mission for the LS&T Program is to develop advanced lasers, optics, and materials technologies and applications to solve problems and create new capabilities of importance to the Laboratory and the nation. This mission statement has been our guide for defining work appropriate for our Program. A major new focus of LS&T beginning this past year has been the development of high peak power short-pulse capability for the National Ignition Facility (NIF). LS&T is committed to this activity.« less

Aura of technology and the cutting edge: a history of lasers in neurosurgery.

PubMed

Ryan, Robert W; Spetzler, Robert F; Preul, Mark C

2009-09-01

In this historical review the authors examine the important developments that have led to the availability of laser energy to neurosurgeons as a unique and sometimes invaluable tool. They review the physical science behind the function of lasers, as well as how and when various lasers based on different lasing mediums were discovered. They also follow the close association between advances in laser technology and their application in biomedicine, from early laboratory experiments to the first clinical experiences. Because opinions on the appropriate role of lasers in neurosurgery vary widely, the historical basis for some of these views is explored. Initial enthusiasm for a technology that appears to have innate advantages for safe resections has often given way to the strict limitations and demands of the neurosurgical operating theater. However, numerous creative solutions to improve laser delivery, power, safety, and ergonomics demonstrate the important role that technological advances in related scientific fields continue to offer neurosurgery. Benefiting from the most recent developments in materials science, current CO(2) laser delivery systems provide a useful addition to the neurosurgical armamentarium when applied in the correct circumstances and reflect the important historical advances that come about from the interplay between neurosurgery and technology.

Laser-Hybrid welding, an innovative technology to join automotive body parts

NASA Astrophysics Data System (ADS)

Sieben, Manuel; Brunnecker, Frank

The design of Tail lamps has been changed dramatically since cars built. At modern lamps, the lenses are absolutely transparent and allow a direct view onto the weld seam. Conventional welding technologies, such as vibration and hot plate welding cannot compete with this demand. Focused on this targeted application, LPKF Laser & Electronics AG has developed in cooperation with the Bavarian Laser Centre a unique Laser welding technology called hybrid welding.

Hollow Core Fiber Optics for Mid-Wave and Long-Wave Infrared Spectroscopy

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

Kriesel, J.M.; Gat, N.; Bernacki, Bruce E.

The development and testing of hollow core glass waveguides (i.e., fiber optics) for use in Long-Wave Infrared (LWIR) spectroscopy systems is described. LWIR fiber optics are a key enabling technology needed to improve the utility and effectiveness of trace chemical detection systems based in the 8 to 12 micron region. This paper focuses on recent developments in hollow waveguide technology geared specifically for LWIR spectroscopy, including a reduction in both the length dependent loss and the bending loss while maintaining relatively high beam quality. Results will be presented from tests conducted with a Quantum Cascade Laser.

Full color laser projection display using Kr-Ar laser (white laser) beam-scanning technology

NASA Astrophysics Data System (ADS)

Kim, Yonghoon; Lee, Hang W.; Cha, Seungnam; Lee, Jin-Ho; Park, Youngjun; Park, Jungho; Hong, Sung S.; Hwang, Young M.

1997-07-01

Full color laser projection display is realized on the large screen using a krypton-argon laser (white laser) as a light source, and acousto-optic devices as light modulators. The main wavelengths of red, green and blue color are 647, 515, and 488 nm separated by dichroic mirrors which are designed to obtain the best performance for the s-polarized beam with the 45 degree incident angle. The separated beams are modulated by three acousto-optic modulators driven by rf drivers which has energy level of 1 watt at 144 MHz and recombined by dichroic mirrors again. Acousto-optic modulators (AOM) are fabricated to satisfy high diffraction efficiency over 80% and fast rising time less than 50 ns at the video bandwidth of 5 MHz. The recombined three beams (RGB) are scanned by polygonal mirrors for horizontal lines and a galvanometer for vertical lines. The photodiode detection for monitoring of rotary polygonal mirrors is adopted in this system for the compensation of the tolerance in the mechanical scanning to prevent the image joggling in the horizontal direction. The laser projection display system described in this paper is expected to apply HDTV from the exploitation of the acousto- optic modulator with the video bandwidth of 30 MHz.

Selective treatment of carious dentin using a mid-infrared tunable pulsed laser at 6 μm wavelength range

NASA Astrophysics Data System (ADS)

Saiki, Masayuki; Ishii, Katsunori; Yoshikawa, Kazushi; Yasuo, Kenzo; Yamamoto, Kazuyo; Awazu, Kunio

2011-03-01

Optical technologies have good potential for caries detection, prevention, excavation, and the realization of minimal intervention dentistry. This study aimed to develop a selective excavation technique of carious tissue using the specific absorption in 6 μm wavelength range. Bovine dentin demineralized with lactic acid solution was used as a carious dentin model. A mid-infrared tunable pulsed laser was obtained by difference-frequency generation technique. The wavelength was tuned to 6.02 and 6.42 μm which correspond to absorption bands called amide I and amide II, respectively. The laser delivers 5 ns pulse width at a repetition rate of 10 Hz. The morphological change after irradiation was observed with a scanning electron microscope, and the measurement of ablation depth was performed with a confocal laser microscope. At λ = 6.02 μm and the average power density of 15 W/cm2, demineralized dentin was removed selectively with less-invasive effect on sound dentin. The wavelength of 6.42 μm also showed the possibility of selective removal. High ablation efficiency and low thermal side effect were observed using the nanosecond pulsed laser with λ = 6.02 μm. In the near future, development of compact laser device will open the minimal invasive laser treatment to the dental clinic.

Plant-Stress Measurements Using Laser-Induced Fluorescence Excitation: Poland Experiment

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

Gene Capelle; Steve Jones

1999-05-01

Bechtel Nevada's Special Technologies Laboratory (STL) has been involved in remote sensing for many years, and in April 1995 STL began to study the use of active remote sensing for detecting plant stress. This work was motivated by the need to detect subsurface contamination, with the supposition that this could be accomplished by remote measurement of optical signatures from the overgrowing vegetation. The project has been a cooperative DOE/Disney effort, in which basic optical signature measurements (primarily fluorescence) were done at the Disney greenhouse facilities at Epcot Center in Florida, using instrumentation developed by STL on DOE funding. The primarymore » instrument is a LIFI system, which had originally been developed for detection of surface uranium contamination at DOE sites. To deal specifically with the plant stress measurements, a LIFS system was built that utilizes the same laser, but captures the complete fluorescence spectrum from blue to red wavelengths. This system had continued to evolve, and the version in existence in September 1997 was sent to Poland, accompanied by two people from STL, for the purpose of making the measurements described in this report.« less

Pre-processing of data coming from a laser-EMAT system for non-destructive testing of steel slabs.

PubMed

Sgarbi, Mirko; Colla, Valentina; Cateni, Sivia; Higson, Stuart

2012-01-01

Non destructive test systems are increasingly applied in the industrial context for their strong potentialities in improving and standardizing quality control. Especially in the intermediate manufacturing stages, early detection of defects on semi-finished products allow their direction towards later production processes according to their quality, with consequent considerable savings in time, energy, materials and work. However, the raw data coming from non destructive test systems are not always immediately suitable for sophisticated defect detection algorithms, due to noise and disturbances which are unavoidable, especially in harsh operating conditions, such as the ones which are typical of the steelmaking cycle. The paper describes some pre-processing operations which are required in order to exploit the data coming from a non destructive test system. Such a system is based on the joint exploitation of Laser and Electro-Magnetic Acoustic Transducer technologies and is applied to the detection of surface and sub-surface cracks in cold and hot steel slabs. Copyright © 2011 ISA. Published by Elsevier Ltd. All rights reserved.

Generating the local oscillator "locally" in continuous-variable quantum key distribution based on coherent detection

DOE PAGES

Qi, Bing; Lougovski, Pavel; Pooser, Raphael C.; ...

2015-10-21

Continuous-variable quantum key distribution (CV-QKD) protocols based on coherent detection have been studied extensively in both theory and experiment. In all the existing implementations of CV-QKD, both the quantum signal and the local oscillator (LO) are generated from the same laser and propagate through the insecure quantum channel. This arrangement may open security loopholes and limit the potential applications of CV-QKD. In our paper, we propose and demonstrate a pilot-aided feedforward data recovery scheme that enables reliable coherent detection using a “locally” generated LO. Using two independent commercial laser sources and a spool of 25-km optical fiber, we construct amore » coherent communication system. The variance of the phase noise introduced by the proposed scheme is measured to be 0.04 (rad 2), which is small enough to enable secure key distribution. This technology opens the door for other quantum communication protocols, such as the recently proposed measurement-device-independent CV-QKD, where independent light sources are employed by different users.« less

Development of an EMCCD for lidar applications

NASA Astrophysics Data System (ADS)

De Monte, B.; Bell, R. T.

2017-11-01

A novel detector, incorporating e2v's L3 CCD (L3Vision™) [1] technology for use in LIDAR (Light Detection And Ranging) applications has been designed, manufactured and characterised. The most critical performance aspect was the requirement to collect charge from a 120μm square detection area for a 667ns temporal sampling window, with low crosstalk between successive samples, followed by signal readout with sub-electron effective noise. Additional requirements included low dark signal, high quantum efficiency at the 355nm laser wavelength and the ability to handle bright laser echoes, without corruption of the much fainter useful signals. The detector architecture used high speed charge binning to combine signal from each sampling window into a single charge packet. This was then passed through a multiplication register (Electron Multiplying Charge Coupled Device) operating with a typical gain of 100X to a conventional charge detection circuit. The detector achieved a typical quantum efficiency of 80% and a total noise in darkness of < 0.5 electrons rms. Development of the detector was supported by ESA (European Space Agency).

Tunable diode laser absorption spectroscopy as method of choice for non-invasive and automated detection of microbial growth in media fills.

PubMed

Brueckner, David; Roesti, David; Zuber, Ulrich; Sacher, Meik; Duncan, Derek; Krähenbühl, Stephan; Braissant, Olivier

2017-05-15

Tunable diode laser absorption spectroscopy (TDLAS) was evaluated on its potential to detect bacterial growth of contaminated media fill vials. The target was a replacement/ automation of the traditional visual media fill inspection. TDLAS was used to determine non-invasively O 2 and/or CO 2 changes in headspaces of such vials being induced by metabolically active microorganisms. Four different vial formats, 34 microorganisms (inoculation volume<10 cells) and two different media (TSB/FTM) were tested. Applying parallel CO 2 and O 2 headspace measurements all format-organism combinations were detected within <11 days reliably with reproducible results. False negatives were exclusively observed for samples that were intentionally breached with syringes of 0.3mm in diameter. Overall it was shown that TDLAS functionality for a replacement of the visual media fill inspection is given and that investing in further validation and implementation studies is valuable. Nevertheless, some small but vincible challenges remain to have this technology in practical use. Copyright © 2017 Elsevier B.V. All rights reserved.

Fabrication and characterization of micromachined dielectric thin films and temperature sensors using thermoluminescence

NASA Astrophysics Data System (ADS)

Kim, Sangho Sam

High-power laser technology has a number of applications, whether for the military (i.e., anti-missile weaponry) or for material processing, medical surgery, laser-induced nuclear fusion, and high-density data storage. However, external obstacles could cause a laser to problematically change its direction. Optical components such as mirrors already address this problem by deflecting a laser beam, but can be damaged easily due to the intensity of the laser. Therefore, this dissertation examines how to improve reliability of high power laser application systems by three significant standards. First, we demonstrate that an atomic layer deposition (ALD) of Al2O3 can stabilize novel dielectric optical mirrors composed of SiO2 nanorods, whose porosity makes it attractive for use as a low refractive index material. Such a deposition can stabilize material properties in dry versus humid atmospheres, where both the refractive index and coefficient of thermal expansion (CTE) vary dramatically. This encapsulation ability is demonstrated in dielectric multilayers as a Distributed Bragg Reflector (DBR). Second, we show that the difference in hydroxyl signatures of micromachined dielectric membranes can make detection of optical materials' laser damage more accurate. This signature difference, appearing as the decrease in post-laser absorption peaks associated with hydroxyl groups (OH), is measured by Fourier transform infrared spectroscopy and corresponds to regions of high fluence from a Nd:YAG laser. This detection technique will be useful to determine the lifespan of the optical components used in a high power laser. Third, we find that heterogeneous thermoluminescent (TL) multilayers composed of LiF:Mg,Ti and CaF2:Dy with Kapton as an interlayer can enhance reconstruction of laser heating events through thermal gradients that penetrate deep into a material, thereby preserving memory of the temperature history of the surface. Using the finite-difference time-domain method (FDTD) and the first order kinetics model of TL, we estimate dynamic heat transfer and then populate the final luminescent intensity. A thermal contact conductance between the critical layers is also introduced to better simulate experimental results, thereby resolving dynamic temperatures by hundreds of milliseconds.

Comparison of SP-LIBS and DP-LIBS on metal and non-metal testing based on LIBS

NASA Astrophysics Data System (ADS)

Lin, Xiaomei; Sun, Haoran; Lin, Jingjun

2017-10-01

Laser-induced breakdown spectroscopy (LIBS) technology for metal and nonmetallic detection accuracy is the key technology to be solved in LIBS measurement, Due to metal elements and non-metallic elements in the lively, atomic structure and the degree of excitation of the laser are totally different, so the laser induced plasma evolution and spectral intensity are absolutely different. Among the many factors that affect measurement accuracy, the single and double pulse of the laser has a great influence on the measurement accuracy of metal and non-metal, they both have their own advantages, but also have their own shortcomings. In order to compare the effect of SP-LIBS and DP-LIBS on the measurement results of different elements, in this experiment, we put the metal element aluminum and non-metallic element carbon as the sample, the laser energy as a variable, using the high-speed camera shooting SP- LIBS and DP- LIBS plasma images. Using the spectral analyzer to record the spectral intensity of the elements, by calculating the relative RSD of the signal intensity and comparing the spectral intensity and the signal stability for different elements, develop an optimized experimental program. The experimental results show that under the same energy condition, the metal aluminum ion image under the DP- LIBS and the non-metallic carbon ion image under the SP- LIBS are the most suitable images. By considering the stability of the line intensity and the signal stability, we find that the sensitivity and stability of the signal strength of the metal elements under the double pulse are better than that of the single pulse, and for the non-metallic element, the single pulse laser is better than the double pulse.

IR technology for enhanced force protection by AIM

NASA Astrophysics Data System (ADS)

Breiter, R.; Ihle, T.; Rode, W.; Wendler, J.; Rühlich, I.; Haiml, M.; Ziegler, J.

2008-04-01

In all recent missions our forces are faced with various types of asymmetric threads like snipers, IEDs, RPGs or MANPADS. 2 nd and 3 rd Gen IR technology is a backbone of modern force protection by providing situational awareness and accurate target engagement at day/night. 3 rd Gen sensors are developed for thread warning capabilities by use of spectral or spatial information. The progress on a dual-color IR module is discussed in a separate paper [1]. A 1024x256 SWIR array with flexure bearing compressor and pulse tube cold finger provides > 50,000h lifetime for space or airborne hyperspectral imaging in pushbroom geometry with 256 spectral channels for improved change detection and remote sensing of IEDs or chemical agents. Similar concepts are pursued in the LWIR with either spectroscopic imaging or a system of LWIR FPA combined with a cooled tunable Laser to do spectroscopy with stimulated absorption of specific wavelengths. AIM introduced the RangIR sight to match the requirements of sniper teams, AGLs and weapon stations, extending the outstanding optronic performance of the fielded HuntIR with position data of a target by a laser range finder (LRF), a 3 axis digital magnetic compass (DMC) and a ballistic computer for accurate engagement of remote targets. A version with flexure bearing cooler with >30,000h life time is being developed for continuous operation in e.g. gunfire detection systems. This paper gives an overview of AIM's technologies for enhanced force protection.

Study on initiative vibration absorbing technology of optics in strong disturbed environment

NASA Astrophysics Data System (ADS)

Jia, Si-nan; Xiong, Mu-di; Zou, Xiao-jie

2007-12-01

Strong disturbed environment is apt to cause irregular vibration, which seriously affects optical collimation. To improve the performance of laser beam, three-point dynamic vibration absorbing method is proposed, and laser beam initiative vibration absorbing system is designed. The maladjustment signal is detected by position sensitive device (PSD), three groups of PZT are driven to adjust optical element in real-time, so the performance of output-beam is improved. The coupling model of the system is presented. Multivariable adaptive closed-loop decoupling arithmetic is used to design three-input-three-output decoupling controller, so that high precision dynamic adjusting is realized. Experiments indicate that the system has good shock absorbing efficiency.

LIGO - The Laser Interferometer Gravitational-Wave Observatory

NASA Technical Reports Server (NTRS)

Abramovici, Alex; Althouse, William E.; Drever, Ronald W. P.; Gursel, Yekta; Kawamura, Seiji; Raab, Frederick J.; Shoemaker, David; Sievers, Lisa; Spero, Robert E.; Thorne, Kip S.

1992-01-01

The goal of the Laser Interferometer Gravitational-Wave Observatory (LIGO) Project is to detect and study astrophysical gravitational waves and use data from them for research in physics and astronomy. LIGO will support studies concerning the nature and nonlinear dynamics for gravity, the structures of black holes, and the equation of state of nuclear matter. It will also measure the masses, birth rates, collisions, and distributions of black holes and neutron stars in the universe and probe the cores of supernovae and the very early universe. The technology for LIGO has been developed during the past 20 years. Construction will begin in 1992, and under the present schedule, LIGO's gravitational-wave searches will begin in 1998.

Deep frequency modulation interferometry.

PubMed

Gerberding, Oliver

2015-06-01

Laser interferometry with pm/Hz precision and multi-fringe dynamic range at low frequencies is a core technology to measure the motion of various objects (test masses) in space and ground based experiments for gravitational wave detection and geodesy. Even though available interferometer schemes are well understood, their construction remains complex, often involving, for example, the need to build quasi-monolithic optical benches with dozens of components. In recent years techniques have been investigated that aim to reduce this complexity by combining phase modulation techniques with sophisticated digital readout algorithms. This article presents a new scheme that uses strong laser frequency modulations in combination with the deep phase modulation readout algorithm to construct simpler and easily scalable interferometers.

Advances in laser technology and fibre-optic delivery systems in lithotripsy.

PubMed

Fried, Nathaniel M; Irby, Pierce B

2018-06-08

The flashlamp-pumped, solid-state holmium:yttrium-aluminium-garnet (YAG) laser has been the laser of choice for use in ureteroscopic lithotripsy for the past 20 years. However, although the holmium laser works well on all stone compositions and is cost-effective, this technology still has several fundamental limitations. Newer laser technologies, including the frequency-doubled, double-pulse YAG (FREDDY), erbium:YAG, femtosecond, and thulium fibre lasers, have all been explored as potential alternatives to the holmium:YAG laser for lithotripsy. Each of these laser technologies is associated with technical advantages and disadvantages, and the search continues for the next generation of laser lithotripsy systems that can provide rapid, safe, and efficient stone ablation. New fibre-optic approaches for safer and more efficient delivery of the laser energy inside the urinary tract include the use of smaller-core fibres and fibres that are tapered, spherical, detachable or hollow steel, or have muzzle brake distal fibre-optic tips. These specialty fibres might provide advantages, including improved flexibility for maximal ureteroscope deflection, reduced cross section for increased saline irrigation rates through the working channel of the ureteroscope, reduced stone retropulsion for improved stone ablation efficiency, and reduced fibre degradation and burnback for longer fibre life.

Implementation of laser technology and treatment at county level in the Swedish Public Dental Service.

PubMed

Bergholm, Åsa; Östberg, Anna-Lena; Gabre, Pia

2014-01-01

The aim of this study was to obtain an understanding of the factors that affected the way new technology and methods were used in dentistry after a training program. A qualitative research method was used to collect data. Nine dentists working in the Public Dental Service (PDS) in Uppsala County in Sweden agreed to be interviewed in the study. They worked in five different clinics, all with laser equipment, and had received training in the use of lasers. The interviews were tape recorded and transcribed, and were analysed using manifest and latent qualitative content analysis. The categories in this study were identified as "Prerequisites and obstacles to imple- mentation", "Attitudes to laser technology and treatments" and "Laser technology in the future'". The dentists described working with lasers as complicated and problematic. They had concerns about the method relating to the working environment, evidence of efficacy of treatment, costs, and benefits for patients and dentists. The main finding was that the decision to adopt the technology seemed to be based on individual perceptions of the value of lasers compared to other ways of achieving the same goal. They provided uniform proposals regarding how an organization should implement new methods, including an emphasis on the importance of preparation and having opportunities to be able to test and evaluate the technology. Another important factor was support from surrounding staff, colleagues and management. Despite all the barriers, the respondents were positive about working with lasers in the future, mainly due to their belief that patients would demand laser treatment. In conclusion both individual and organizational factors affected the extent to which the respondents used the laser. The main finding was the individual perception of the value of lasers compared to other methods which could achieve the same goal.

[Rapid multi-elemental analysis on four precious Tibetan medicines based on LIBS technique].

PubMed

Liu, Xiao-na; Shi, Xin-yuan; Jia, Shuai-yun; Zhao, Na; Wu, Zhi-sheng; Qiao, Yan-jiang

2015-06-01

The laser-induced breakdown spectroscopy (LIBS) was applied to perform a qualitative elementary analysis on four precious Tibetan medicines, i. e. Renqing Mangjue, Renqing Changjue, 25-herb coral pills and 25-herb pearl pills. The specific spectra of the four Tibetan medicines were established. In the experiment, Nd: YAG and 1 064 nm-baseband pulse laser were adopted to collect the spectra. A laser beam focused on the surface of the samples to generate plasma. Its spectral signal was detected by using spectrograph. Based on the National Institute of Standard and Technology (NIST) database, LIBS spectral lines were indentified. The four Tibetan medicines mainly included Ca, Na, K, Mg and other elements and C-N molecular band. Specifically, Fe was detected in Renqing Changjue and 25-herb pearl pills; heavy mental elements Hg and Cu were shown in Renqing Mangjue and Renqing Changjue; Ag was found in Renqing Changjue. The results demonstrated that LIBS is a reliable and rapid multi-element analysis on the four Tibetan medicines. With Real-time, rapid and nondestructive advantages, LIBS has a wide application prospect in the element analysis on ethnic medicines.

Laser diode arrays for naval reconnaissance

NASA Astrophysics Data System (ADS)

Holloway, John H., Jr.; Crosby, Frank J.; Petee, Danny A.; Suiter, Harold R.; Witherspoon, Ned H.

2003-09-01

The Airborne Littoral Reconnaissance Technologies (ALRT) Project has demonstrated a nighttime operational minefield detection capability using commercial off-the-shelf high-power Laser Diode Arrays (LDAs). Historically, optical aerial detection of minefields has primarily been limited to daytime operations but LDAs promise compact and efficient lighting to allow for enhanced reconnaissance operations for future mine detection systems. When combined with high-resolution intensified imaging systems, LDAs can illuminate otherwise unseen areas. Future wavelength options will open the way for active multispectral imaging with LDAs. The Coastal Systems Station working for the Office of Naval Research on the ALRT project has designed, developed, integrated, and tested both prototype and commercial arrays from a Cessna airborne platform. Detailed test results show the ability to detect several targets of interest in a variety of background conditions. Initial testing of the prototype arrays, reported on last year, was completed and further investigations of the commercial versions were performed. Polarization-state detection studies were performed, and advantageous properties of the source-target-sensor geometry noted. Current project plans are to expand the field-of-view coverage for Naval exercises in the summer of 2003. This paper describes the test collection, data library products, array information, on-going test analysis results, and future planned testing of the LDAs.

ADVANCES IN IMAGING TECHNOLOGIES IN THE EVALUATION OF HIGH-GRADE BLADDER CANCER

PubMed Central

Zlatev, Dimitar V.; Altobelli, Emanuela; Liao, Joseph C.

2015-01-01

Bladder cancer is a heterogeneous disease that ranges from low-grade variant with an indolent course, to high-grade subtype with a recurrent, progressive, and potentially lethal outcome. Accurate assessment for individualized treatment depends critically on the diagnostic accuracy of white light cystoscopy. Despite its central role, white light cystoscopy has several well-documented shortcomings including difficult flat lesion detection, imprecise tumor delineation that limits complete resection, differentiation between inflammation and malignancy, and grade and stage determination. As the limitations of white light cystoscopy contribute to the risk of cancer persistence, recurrence, and progression, there is a need for improved visualization of flat, multifocal, high-grade, and muscle-invasive lesions. Optical imaging technologies have emerged as an adjunct to white light cystoscopy with the goal to guide more effective treatment by improving cancer detection and patient stratification on the basis of grade and stage. Photodynamic diagnosis and narrow band imaging are macroscopic imaging modalities similar to white light cystoscopy, but provide additional contrast enhancement of bladder tumors and have been shown to improve detection rates. Confocal laser endomicroscopy and optical coherence tomography are microscopic imaging technologies that enable real-time high resolution, subsurface tissue characterization with spatial resolutions similar to histology. Molecular imaging offers the potential for the combination of optical imaging technologies with cancer-specific molecular agents to improve the specificity of disease detection. PMID:25882557

Receiver Signal to Noise Ratios for IPDA Lidars Using Sine-wave and Pulsed Laser Modulation and Direct Detections

NASA Technical Reports Server (NTRS)

Sun, Xiaoli; Abshire, James B.

2011-01-01

Integrated path differential absorption (IPDA) lidar can be used to remotely measure the column density of gases in the path to a scattering target [1]. The total column gas molecular density can be derived from the ratio of the laser echo signal power with the laser wavelength on the gas absorption line (on-line) to that off the line (off-line). 80th coherent detection and direct detection IPDA lidar have been used successfully in the past in horizontal path and airborne remote sensing measurements. However, for space based measurements, the signal propagation losses are often orders of magnitude higher and it is important to use the most efficient laser modulation and detection technique to minimize the average laser power and the electrical power from the spacecraft. This paper gives an analysis the receiver signal to noise ratio (SNR) of several laser modulation and detection techniques versus the average received laser power under similar operation environments. Coherent detection [2] can give the best receiver performance when the local oscillator laser is relatively strong and the heterodyne mixing losses are negligible. Coherent detection has a high signal gain and a very narrow bandwidth for the background light and detector dark noise. However, coherent detection must maintain a high degree of coherence between the local oscillator laser and the received signal in both temporal and spatial modes. This often results in a high system complexity and low overall measurement efficiency. For measurements through atmosphere the coherence diameter of the received signal also limits the useful size of the receiver telescope. Direct detection IPDA lidars are simpler to build and have fewer constraints on the transmitter and receiver components. They can use much larger size 'photon-bucket' type telescopes to reduce the demands on the laser transmitter. Here we consider the two most widely used direct detection IPDA lidar techniques. The first technique uses two CW seeder lasers, one on-line and one offline that are intensity modulated by two different frequency sine-waves signals before being amplified by a common laser amplifier. The receiver uses narrowband amplitude demodulation, or lock-in, Signal processing at the given laser modulation frequencies [3,4]. The laser transmitter operates in a quasi CW mode with the peak power equal to twice the average power. The on-line and off-line lasers can be transmitted at the same time without interference. Another direct detection technique uses a low duty cycle pulsed laser modulation [5,6] with the laser wavelengths alternating between on-line and off-line on successive pulses. The receiver uses time resolved detection and can also provide simultaneous target range measurement. With a lower laser duty cycle it requires a much higher peak laser power for the same average power.

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.

Experimental demonstration of distributed feedback semiconductor lasers based on reconstruction-equivalent-chirp technology.

PubMed

Li, Jingsi; Wang, Huan; Chen, Xiangfei; Yin, Zuowei; Shi, Yuechun; Lu, Yanqing; Dai, Yitang; Zhu, Hongliang

2009-03-30

In this paper we report, to the best of our knowledge, the first experimental realization of distributed feedback (DFB) semiconductor lasers based on reconstruction-equivalent-chirp (REC) technology. Lasers with different lasing wavelengths are achieved simultaneously on one chip, which shows a potential for the REC technology in combination with the photonic integrated circuits (PIC) technology to be a possible method for monolithic integration, in that its fabrication is as powerful as electron beam technology and the cost and time-consuming are almost the same as standard holographic technology.

A three-dimensional laser vibration measurement technology realized on five laser beam and its calibration

NASA Astrophysics Data System (ADS)

Li, Lu-Ke; Zhang, Shen-Feng

2018-03-01

Put forward a kind of three-dimensional vibration information technology of vibrating object by the mean of five laser beam of He-Ne laser, and with the help of three-way sensor, measure the three-dimensional laser vibration developed by above mentioned technology. The technology based on the Doppler principle of interference and signal demodulation technology, get the vibration information of the object, through the algorithm processing, extract the three-dimensional vibration information of space objects, and can achieve the function of angle calibration of five beam in the space, which avoid the effects of the mechanical installation error, greatly improve the accuracy of measurement. With the help of a & B K4527 contact three axis sensor, measure and calibrate three-dimensional laser vibrometer, which ensure the accuracy of the measurement data. Summarize the advantages and disadvantages of contact and non-contact sensor, and analysis the future development trends of the sensor industry.

Water Vapor Sensors Go Sky-High to Assure Aircraft Safety

NASA Technical Reports Server (NTRS)

2006-01-01

JPL used a special tunable diode laser, which NASA scientists could tune to different wavelengths, like a radio being tuned to different frequencies, to accurately target specific molecules and detect small traces of gas. This tunable diode laser was designed to emit near-infrared light at wavelengths absorbed by the gas or gases being detected. The light energy being absorbed by the target gas is related to the molecules present. This is usually measured in parts per million or parts per billion. Multiple measurements are made every second, making the system quick to respond to variations in the target gas. NASA scientists developed this technology as part of the 1999 Mars Polar Lander mission to explore the possibility of life-giving elements on Mars. NASA has since used the tunable diode laser-based gas sensor on aircraft and on balloons to successfully study weather and climate, global warming, emissions from aircraft, and numerous other areas where chemical gas analysis is needed. SpectraSensors, Inc., was formed in 1999 as a spinoff company of JPL, to commercialize tunable diode laser-based analyzers for industrial gas-sensing applications (Spinoff 2000). Now, the San Dimas, California-based firm has come back to the market with a new product featuring the NASA-developed instrument for atmospheric monitoring. This instrument is now helping aircraft avoid hazardous weather conditions and enabling the National Weather Service to provide more accurate weather forecasts.

New photoacoustic platform for early detection of circulating clots to prevent stroke and other fatal thromboembolic complications (Conference Presentation)

NASA Astrophysics Data System (ADS)

Carey, Kai A.

2017-03-01

Nearly 800,000 people in the U.S. experience an incident of stroke each year; 80% of these are first time occurrences and 87% are ischemic in nature. Someone dies of a stroke every few minutes in the U.S. but despite its prevalence there have been minimal advances in the early detection and screening of thromboembolic events, especially during patient post-operative periods or in genetically predisposed individuals. Environmental or genetic factors may disrupt the balance between coagulation and lysis of micro-thrombi in circulation and increase the risk of stroke. We introduced here a novel in vivo multicolor negative-contrast photoacoustic (PA) flow cytometry (PAFC ) platform with many innovations including customized high pulse repetition rate 1064 laser from IPG Photonics Corporation, powerful laser diode array, multichannel optical schematic, and time-resolved recording system. Using animal models, we verified the potential of this technology to detect small clots in relatively large vessels in vivo. If future clinical trials using a cost-effective, easy-to-use, safe, watch-like, wearable PA probe are successful, PAFC could provide breakthroughs in early monitoring of the growth in size and number of small clots that may predict and potentially prevent fatal thromboembolic complications. We also believe that this technology could be utilized to assess therapeutic benefits of anticoagulants and develop more efficient dosage in treatments by analyzing changes in the composition and frequency of micro-thrombi

Laser Induced Fluorescence (LIF) as a Remote Sensing Tool: A Review

NASA Technical Reports Server (NTRS)

Chappelle, E. W.; Kim, M. S.; Mulchi, C. L.; Daughtry, C. S. T.; McMurtrey, J.; Corp, L.

1998-01-01

Vegetational changes are primary indicators of the present and future ecological status of the globe. These are changes which not only impact upon the primary productivity, but the total of the biogeochemical processes occurring on the planet. The impacts of global climatic and other environmental changes on vegetation must be monitored by some means in order to develop models which will allow us to predict long term effects. Large scale monitoring is now possible only with remote sensing systems, primarily passive reflectance, obtained by the use of satellite and aircraft platforms. However, passive reflectance techniques at this time are limited in their ability to detect subtle changes in the concentration and oxidation states of the many compounds involved in the light reactions of photosynthesis. Knowledge of these changes we consider to be fundamental in the remote assessment of both the rate and efficiency of photosynthesis and also the early detection of stress damage. The above factors pointed to the desirability of a sensing technique with the sensitivity and specificity necessary for detecting and quantifying those biological entities involved in photosynthesis. Another optical technique for vegetation monitoring is fluorescence. Previously, the lack of adequate excitation light sources and detector technologies have limited the use of fluorescence on intact plant leaves in the field. It is only recently with the advent of lasers with short pulse duration and advanced detector technologies that fluorescence measurements in the remote mode have become possible in the presence of ambient light.