CO2 laser application in gynecology: experience in microsurgery of cervical lesions

NASA Astrophysics Data System (ADS)

Knapp, Piotr A.

1995-03-01

A CO2 laser device was used for treating cervical lesions in 1574 patients. Of the total, 163 were diagnosed as CIN. Patients were selected for the study as a result of mass screening during the period from 1988 to 1992 of Bialystok Province, Poland. Treatment of cervical lesions with laser proved to be effective. In the author's opinion it is an essential step in preventing cervical malignancy.

Clinical applications of CO2 laser resurfacing in the treatment of various pathologic skin disorders

NASA Astrophysics Data System (ADS)

Giler, Shamai

1997-12-01

CO2 laser skin resurfacing devices are widely used in cosmetic surgery for the treatment of facial rhytides, acne scars and aging skin. This technique is also useful in the treatment of various benign and premalignant or multiple pathological skin conditions and disorders originating in the epidermal, dermal and skin appendages, vascular lesions, epidermal nevi, infected wounds and ulcers, and keloids. Various surgical techniques have been developed in our clinic using laser resurfacing in the treatment of more than 2,000 patients with various skin pathologic disorders. We describe our experience with the various techniques used. The precise depth control and ablation properties combined with the hemostatic and sterilizing effects of the CO2 laser beam, reduction of the possibility of bleeding, infection and damage to healthy tissues, make the CO2 laser resurfacing techniques the treatment of choice for cosmetic surgery and treatment of benign, premalignant and multiple pathologic skin conditions.

A Preliminary Report on the CO2 Laser for Lumbar Fusion: Safety, Efficacy and Technical Considerations.

PubMed

Villavicencio, Alan T; Burneikiene, Sigita; Babuska, Jason M; Nelson, Ewell L; Mason, Alexander; Rajpal, Sharad

2015-04-01

The purpose of this study was to evaluate potential technical advantages of the CO2 laser technology in mini-open transforaminal lumbar interbody fusion (TLIF) surgeries and report our preliminary clinical data on the safety and clinical outcomes. There is currently no literature discussing the recently redeveloped CO2 laser technology application for lumbar fusion. Safety and clinical outcomes were compared between two groups: 24 patients that underwent CO2 laser-assisted one-level TLIF surgeries and 30 patients that underwent standard one-level TLIF surgeries without the laser. There were no neural thermal injuries or other intraoperative laser-related complications encountered in this cohort of patients. At a mean follow-up of 17.4 months, significantly reduced lower back pain scores (P=0.013) were reported in the laser-assisted patient group compared to a standard fusion patient group. Lower extremity radicular pain intensity scores were similar in both groups. Laser-assisted TLIF surgeries showed a tendency (P = 0.07) of shorter operative times that was not statistically significant. Based on this preliminary clinical report, the safety of the CO2 laser device for lumbar fusion surgeries was assessed. There were no neural thermal injuries or other intraoperative laser-related complications encountered in this cohort of patients. Further investigation of CO2 laser-assisted lumbar fusion procedures is warranted in order to evaluate its effect on clinical outcomes.

Ex vivo evaluation of super pulse diode laser system with smart temperature feedback for contact soft-tissue surgery

NASA Astrophysics Data System (ADS)

Yaroslavsky, Ilya; Boutoussov, Dmitri; Vybornov, Alexander; Perchuk, Igor; Meleshkevich, Val; Altshuler, Gregory

2018-02-01

Until recently, Laser Diodes (LD) have been limited in their ability to deliver high peak power levels, which, in turn, limited their clinical capabilities. New technological developments made possible advent of "super pulse" LD (SPLD). Moreover, advanced means of smart thermal feedback enable precise control of laser power, thus ensuring safe and optimally efficacious application. In this work, we have evaluated a prototype SPLD system ex vivo. The device provided up to 25 W average and up to 150 W pulse power at 940 nm wavelength. The laser was operated in the thermal feedback-controlled mode, where power of the laser was varied automatically as a function of real-time thermal feedback to maintain constant tip temperature. The system was also equipped with a fiber tip initiated with advanced TiO2 /tungsten technique. Evaluation methods were designed to assess: 1) Speed and depth of cutting; 2) Dimensions of coagulative margin. The SPLD system was compared with industry-leading conventional diode and CO2 devices. The results indicate that the SPLD system provides increase in speed of controlled cutting by a factor of >2 in comparison with the conventional diode laser and approaching that of CO2 device. The produced ratio of the depth of cut to the thermal damage margin was significantly higher than conventional diodes and close to that of the CO2 system, suggesting optimal hemostasis conditions. SPLD technology with real-time temperature control has a potential for creating a new standard of care in the field of precision soft tissue surgery.

Controlling the temperature of bones using pulsed CO2 lasers: observations and mathematical modeling.

PubMed

Lévesque, Luc; Noël, Jean-Marc; Scott, Calum

2015-12-01

Temperature of porcine bone specimens are investigated by aiming a pulsed CO2 laser beam at the bone-air surface. This method of controlling temperature is believed to be flexible in medical applications as it avoids the uses of thermal devices, which are often cumbersome and generate rather larger temperature variations with time. The control of temperature using this method is modeled by the heat-conduction equation. In this investigation, it is assumed that the energy delivered by the CO2 laser is confined within a very thin surface layer of roughly 9 μm. It is shown that temperature can be maintained at a steady temperature using a CO2 laser and we demonstrate that the method can be adapted to be used in tandem with another laser beam. This method to control the temperature is believed to be useful in de-contamination of bone during the implantation treatment, in bone augmentation when using natural or synthetic materials and in low-level laser therapy.

Single-Step Reagentless Laser Scribing Fabrication of Electrochemical Paper-Based Analytical Devices.

PubMed

de Araujo, William R; Frasson, Carolina M R; Ameku, Wilson A; Silva, José R; Angnes, Lúcio; Paixão, Thiago R L C

2017-11-20

A single-step laser scribing process is used to pattern nanostructured electrodes on paper-based devices. The facile and low-cost technique eliminates the need for chemical reagents or controlled conditions. This process involves the use of a CO 2 laser to pyrolyze the surface of the paperboard, producing a conductive porous non-graphitizing carbon material composed of graphene sheets and composites with aluminosilicate nanoparticles. The new electrode material was extensively characterized, and it exhibits high conductivity and an enhanced active/geometric area ratio; it is thus well-suited for electrochemical purposes. As a proof-of-concept, the devices were successfully employed for different analytical applications in the clinical, pharmaceutical, food, and forensic fields. The scalable and green fabrication method associated with the features of the new material is highly promising for the development of portable electrochemical devices. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

120: THE CLINICAL EFFECTIVENESS AND COST-EFFECTIVENESS OF FRACTIONAL CO2 LASER IN ACNE SCARS AND SKIN REJUVENATION: A SYSTEMATIC REVIEW AND ECONOMIC EVALUATION

PubMed Central

Yaaghoobian, Barmak; Sadeghi-Ghyassi, Fatemeh; Hajebrahimi, Sakineh

2017-01-01

Background and aims Skin rejuvenation is one of high demand cosmetic interventions in Iran. Fractional CO2 Laser is a high power ablative laser which has variety of utilization in medicine including treatment of acne scars and rejuvenation. The aim of this study was to evaluate the safety, efficacy, and cost-effectiveness of Fractional CO2 Laser in comparison with other methods of rejuvenation and acne scar treatment. Methods A systematic database search including Medline (via OVID and PubMed), EMBASE, CINHAL, Cochrane Library, CRD, SCOPUS and Web of Science conducted. After screening search results, selected publications appraised by CASP and Cochrane Collaboration's tool for assessing risk of bias and eligible studies included in the systematic review. In economic evaluation, all costs and benefits analyzed from Iran ministry of health's perspective. Results From 2667 publications, two randomized control trials were eligible and included in the study. The affectivity and complications of Fractional CO2 laser were comparable with Er: YAG but Fractional CO2 laser was 14.7% (P=0.01) more effective than Q-Switched ND: YAG laser. Cost affectivity of this method was the same as other alternative lasers. Conclusions Fractional CO2 laser is an effective and safe method for curing several kinds of skin. Never the less there was not sufficient evidence to support its advantage. This device has equal or lower price in comparison to competent technologies except for the non- fractional ablative Co2 laser that has the same or lower price and comparable effects.

Stokes injected Raman capillary waveguide amplifier

DOEpatents

Kurnit, Norman A.

1980-01-01

A device for producing stimulated Raman scattering of CO.sub.2 laser radiation by rotational states in a diatomic molecular gas utilizing a Stokes injection signal. The system utilizes a cryogenically cooled waveguide for extending focal interaction length. The waveguide, in conjunction with the Stokes injection signal, reduces required power density of the CO.sub.2 radiation below the breakdown threshold for the diatomic molecular gas. A Fresnel rhomb is employed to circularly polarize the Stokes injection signal and CO.sub.2 laser radiation in opposite circular directions. The device can be employed either as a regenerative oscillator utilizing optical cavity mirrors or as a single pass amplifier. Additionally, a plurality of Raman gain cells can be staged to increase output power magnitude. Also, in the regenerative oscillator embodiment, the Raman gain cell cavity length and CO.sub.2 cavity length can be matched to provide synchronism between mode locked CO.sub.2 pulses and pulses produced within the Raman gain cell.

Development of terahertz laser diagnostics for electron density measurements.

PubMed

Kawahata, K; Akiyama, T; Tanaka, K; Nakayama, K; Okajima, S

2008-10-01

A two color laser interferometer using terahertz laser sources is under development for high performance operation on the large helical device and for future burning plasma experiments such as ITER. Through investigation of terahertz laser sources, we have achieved high power simultaneous oscillations at 57.2 and 47.6 microm of a CH(3)OD laser pumped by a cw 9R(8) CO(2) laser line. The laser wavelength around 50 microm is the optimum value for future fusion devices from the consideration of the beam refraction effect and signal-to-noise ratio for an expected phase shift due to plasma. In this article, recent progress of the terahertz laser diagnostics, especially in mechanical vibration compensation by using a two color laser operation and terahertz laser beam transmission through a dielectric waveguide, will be presented.

A 2.5-kW industrial CO2 laser

NASA Astrophysics Data System (ADS)

Golov, V. K.; Ivanchenko, A. I.; Krasheninnikov, V. V.; Ponomarenko, A. G.; Shepelenko, A. A.

1986-06-01

A fast-flow laser is reported in which the active medium is excited by a self-sustained dc discharge produced by an electric-discharge device with nonsectioned electrodes. In the laser, two discharge gaps are formed by a flat anode and two cathodes, one on each side of the anode. A gas mixture is driven through the gasdynamic channel by a centrifugal fan rotating at 6000 rpm/min. With a mixture of CO2:N2:He = 2.5:7.5:5 mm Hg, the rated power is 2.5 kW; the maximum power is 4 kW with the mixture 2.5:7.5:10 mm Hg. The general design of the laser is described, and its principal performance characteristics are given.

Low-pressure, high-temperature thermal bonding of polymeric microfluidic devices and their applications for electrophoretic separation

NASA Astrophysics Data System (ADS)

Sun, Yi; Chian Kwok, Yien; Nguyen, Nam-Trung

2006-08-01

A new method for thermally bonding poly(methyl methacrylate) (PMMA) substrates has been demonstrated. PMMA substrates are first engraved by CO2-laser micromachining to form microchannels. Both channel width and depth can be adjusted by varying the laser power and scanning speed. Channel depths from 50 µm to 1500 µm and widths from 150 µm to 400 µm are attained. CO2 laser is also used for drilling and dicing of the PMMA parts. Considering the thermal properties of PMMA, a novel thermal bonding process with high temperature and low bonding pressure has been developed for assembling PMMA sheets. A high bonding strength of 2.15 MPa is achieved. Subsequent inspection of the cross sections of several microdevices reveals that the dimensions of the channels are well preserved during the bonding process. Electroosmotic mobility of the ablated channel is measured to be 2.47 × 10-4 cm2 V-1 s-1. The functionality of these thermally bonded microfluidic substrates is demonstrated by performing rapid and high-resolution electrophoretic separations of mixture of fluorescein and carboxyfluorescein as well as double-stranded DNA ladders (ΦX174-Hae III dsDNA digest). The performance of the CO2 laser ablated and thermally bonded PMMA devices compares favorably with those fabricated by other professional means.

Application of a flexible CO(2) laser fiber for neurosurgery: laser-tissue interactions.

PubMed

Ryan, Robert W; Wolf, Tamir; Spetzler, Robert F; Coons, Stephen W; Fink, Yoel; Preul, Mark C

2010-02-01

The CO(2) laser has an excellent profile for use in neurosurgery. Its high absorption in water results in low thermal spread, sparing adjacent tissue. Use of this laser has been limited to line-of-sight applications because no solid fiber optic cables could transmit its wavelength. Flexible photonic bandgap fiber technology enables delivery of CO(2) laser energy through a flexible fiber easily manipulated in a handheld device. The authors examined and compared the first use of this CO(2) laser fiber to conventional methods for incising neural tissue. Carbon dioxide laser energy was delivered in pulsed or continuous wave settings for different power settings, exposure times, and distances to cortical tissue of 6 anesthetized swine. Effects of CO(2) energy on the tissue were compared with bipolar cautery using a standard pial incision technique, and with scalpel incisions without cautery. Tissue was processed for histological analysis (using H & E, silver staining, and glial fibrillary acidic protein immunohistochemistry) and scanning electron microscopy, and lesion measurements were made. Light microscopy and scanning electron microscopy revealed laser incisions of consistent shape, with central craters surrounded by limited zones of desiccated and edematous tissue. Increased laser power resulted in deeper but not significantly wider incisions. Bipolar cautery lesions showed desiccated and edematous zones but did not incise the pia, and width increased more than depth with higher power. Incisions made without using cautery produced hemorrhage but minimal adjacent tissue damage. The photonic bandgap fiber CO(2) laser produced reliable cortical incisions, adjustable over a range of settings, with minimal adjacent thermal tissue damage. Ease of application under the microscope suggests this laser system has reached true practicality for neurosurgery.

Using a CO2 laser for PIR-detector spoofing

NASA Astrophysics Data System (ADS)

Schleijpen, Ric H. M. A.; van Putten, Frank J. M.

2016-10-01

This paper presents experimental work on the use of a CO2 laser for triggering of PIR sensors. Pyro-electric InfraRed sensors are often used as motion detectors for detection of moving persons or objects that are warmer than their environment. Apart from uses in the civilian domain, also applications in improvised weapons have been encountered. In such applications the PIR sensor triggers a weapon, when moving persons or vehicles are detected. A CO2 laser can be used to project a moving heat spot in front of the PIR, generating the same triggering effect as a real moving object. The goal of the research was to provide a basis for assessing the feasibility of the use of a CO2 laser as a countermeasure against PIR sensors. After a general introduction of the PIR sensing principle a theoretical and experimental analysis of the required power levels will be presented. Based on this quantitative analysis, a set up for indoor experiments to trigger the PIR devices remotely with a CO2 laser was prepared. Finally some selected results of the experiments will be presented. Implications for the use as a countermeasure will be discussed.

New laser surface treatments: cleaning, derusting, deoiling, depainting, deoxidizing, and degreasing

NASA Astrophysics Data System (ADS)

Daurelio, Giuseppe; Chita, Giuseppe; Cinquepalmi, Massimo

1997-08-01

Many materials as substrates and surface products have been tested. Typically ferrous (Carbon Steels and Stainless Steels) and non ferrous (Al and Cu metals and its alloys) ones have been employed. Some epoxy, polyurethane, polyester and acrylic paints in different thickness and color have been tested. Many types of the surface rust and oxide on different bulk material have been undertaken to test. Similarly some different types of oils and greases, usually used in industry against the oxidation, have been studied. Anyway many types of dirt, grit, calcareous one and so on, present on industrial components, have been laser cleaned without using solvents, acid baths and other ones. Different types of laser sources have been employed: an axial fast flow, 1.5 KW CO2 c.w. and pulsed laser source, emitting a 10.6 micrometers beam; a portable CO2 laser, c.w. (1 to 25 W) and pulsed (1 to 100 Hz and 400 ms max pulse duration) source, emitting a 10.6 micrometers beam with a multi-articulated seven mirrors guiding device and focussing head; a portable Nd-YAG laser, Q-switched and normal-mode source. 1st harmonic 1.06 micrometers (6 ns pulse duration), 2nd harmonic 532 nm (120 microsecond(s) duration pulse- 1J max per-pulse) wavelengths, multi-articulated seven mirrors beam guiding device, 20 Hz repetition rate. This lets shots with 600 mJ max energy per pulse and 100 MW peak power per-pulse with a very low beam divergence, 0.5 mrad at full angle; a transverse fast flow 2.5 kW CO2 laser.

Nonlinear optical properties of Nd3+-Li+ co-doped ZnS-PVP thin films

NASA Astrophysics Data System (ADS)

Talwatkar, S. S.; Sunatkari, A. L.; Tamgadge, Y. S.; Muley, G. G.

2018-04-01

The nonlinear optical properties of Nd3+-Li+ co-doped ZnS-PVP nanocomposite were studied using a continuous wave (CW) He-Ne laser (λ = 632.8 nm)by z-scan technique. The nonlinear refractive index (n2), absorption coefficient (β) and third order nonlinear susceptibility (χ(3)) of PVP thin films embedded with Nd3+-Li+ co-doped ZnS NPs was found in the order of 10-7 cm2/W, 10-6 cm/W and 10-7 esu respectively. The nonlinearity found increasing with Nd3+-Li+ co-dopant concentration. Based on the results, it is proposed that this material is a new class of luminescent material suitable in optoelectronics devices application, especially in light-emitting devices, electroluminescent devices, display devices, etc.

In situ investigation of the effect of TiF4 and CO2 laser irradiation on the permeability of eroded enamel.

PubMed

Lepri, Taísa Penazzo; Colucci, Vivian; Turssi, Cecília Pedroso; Corona, Silmara Aparecida Milori

2015-06-01

Interest in erosion and its role in tooth wear has increased considerably. Due to the limited contribution of patients in modifying their dietary habits, therapeutic resources aiming to reduce the progression of erosion-like lesions have been discussed. This study sought to evaluate the effect of TiF4 and CO2 laser in controlling the permeability of in situ eroded enamel. Ten volunteers wore an intraoral palatal device containing two enamel slabs, treated with TiF4 gel and TiF4 gel + CO2 or placebo gel and placebo gel + CO2. After the washout period, volunteers were crossed over to the other treatment. During both phases, specimens were submitted to erosive challenges and then evaluated for permeability measured as the percentage of copper ion penetration over the total enamel thickness. Two-way analysis of variance (ANOVA) revealed that there was a significant interaction between the factors under study (p = 0.0002). Tukey's test showed that TiF4 significantly reduced the enamel permeability of eroded enamel specimens, regardless of whether CO2 laser irradiation was performed. It may be concluded that when the placebo gel was applied, CO2 laser was able to reduce enamel permeability; however, when TiF4 was applied, laser irradiation did not imply a reduction in permeability. TiF4 provided a lower permeability of eroded enamel, regardless of whether the CO2 laser was used. Copyright © 2015 Elsevier Ltd. All rights reserved.

Advanced infrared laser modulator development

NASA Technical Reports Server (NTRS)

Cheo, P. K.; Wagner, R.; Gilden, M.

1984-01-01

A parametric study was conducted to develop an electrooptic waveguide modulator for generating continuous tunable sideband power from an infrared CO2 laser. Parameters included were the waveguide configurations, microstrip dimensions device impedance, and effective dielectric constants. An optimum infrared laser modulator was established and was fabricated. This modulator represents the state-of-the-art integrated optical device, which has a three-dimensional topology to accommodate three lambda/4 step transformers for microwave impedance matching at both the input and output terminals. A flat frequency response of the device over 20 HGz or = 3 dB) was achieved. Maximum single sideband to carrier power greater than 1.2% for 20 W microwave input power at optical carrier wavelength of 10.6 microns was obtained.

Creating compact and microscale features in paper-based devices by laser cutting.

PubMed

Mahmud, Md Almostasim; Blondeel, Eric J M; Kaddoura, Moufeed; MacDonald, Brendan D

2016-11-14

In this work we describe a fabrication method to create compact and microscale features in paper-based microfluidic devices using a CO 2 laser cutting/engraving machine. Using this method we are able to produce the smallest features with the narrowest barriers yet reported for paper-based microfluidic devices. The method uses foil backed paper as the base material and yields inexpensive paper-based devices capable of using small fluid sample volumes and thus small reagent volumes, which is also suitable for mass production. The laser parameters (power and laser head speed) were adjusted to minimize the width of hydrophobic barriers and we were able to create barriers with a width of 39 ± 15 μm that were capable of preventing cross-barrier bleeding. We generated channels with a width of 128 ± 30 μm, which we found to be the physical limit for small features in the chromatography paper we used. We demonstrate how miniaturizing of paper-based microfluidic devices enables eight tests on a single bioassay device using only 2 μL of sample fluid volume.

CF.sub.4 laser

DOEpatents

Wittig, Curt; Tiee, Joe J.

1979-01-01

A CF.sub.4 laser for producing near 16 .mu.m radiation utilizing a line tunable CO.sub.2 laser as an optical pumping source. The device uses a cryogenically cooled optically pumped cell containing molecular CF.sub.4 gas. An optical resonant cavity formed around the optically pumped cell induces oscillations of near 16 .mu.m radiation from the .nu..sub.2 +.nu..sub.4 .fwdarw..nu..sub.2 transition in the molecular CF.sub.4 gas.

Single-ended mid-infrared laser-absorption sensor for simultaneous in situ measurements of H₂O, CO₂, CO, and temperature in combustion flows.

PubMed

Peng, Wen Yu; Goldenstein, Christopher S; Mitchell Spearrin, R; Jeffries, Jay B; Hanson, Ronald K

2016-11-20

The development and demonstration of a four-color single-ended mid-infrared tunable laser-absorption sensor for simultaneous measurements of H₂O, CO₂, CO, and temperature in combustion flows is described. This sensor operates by transmitting laser light through a single optical port and measuring the backscattered radiation from within the combustion device. Scanned-wavelength-modulation spectroscopy with second-harmonic detection and first-harmonic normalization (scanned-WMS-2f/1f) was used to account for variable signal collection and nonabsorption losses in the harsh environment. Two tunable diode lasers operating near 2551 and 2482 nm were utilized to measure H₂O concentration and temperature, while an interband cascade laser near 4176 nm and a quantum cascade laser near 4865 nm were used for measuring CO₂ and CO, respectively. The lasers were modulated at either 90 or 112 kHz and scanned across the peaks of their respective absorption features at 1 kHz, leading to a measurement rate of 2 kHz. A hybrid demultiplexing strategy involving both spectral filtering and frequency-domain demodulation was used to decouple the backscattered radiation into its constituent signals. Demonstration measurements were made in the exhaust of a laboratory-scale laminar methane-air flat-flame burner at atmospheric pressure and equivalence ratios ranging from 0.7 to 1.2. A stainless steel reflective plate was placed 0.78 cm away from the sensor head within the combustion exhaust, leading to a total absorption path length of 1.56 cm. Detection limits of 1.4% H₂O, 0.6% CO₂, and 0.4% CO by mole were reported. To the best of the authors' knowledge, this work represents the first demonstration of a mid-infrared laser-absorption sensor using a single-ended architecture in combustion flows.

Monte-Carlo based Uncertainty Analysis For CO2 Laser Microchanneling Model

NASA Astrophysics Data System (ADS)

Prakash, Shashi; Kumar, Nitish; Kumar, Subrata

2016-09-01

CO2 laser microchanneling has emerged as a potential technique for the fabrication of microfluidic devices on PMMA (Poly-methyl-meth-acrylate). PMMA directly vaporizes when subjected to high intensity focused CO2 laser beam. This process results in clean cut and acceptable surface finish on microchannel walls. Overall, CO2 laser microchanneling process is cost effective and easy to implement. While fabricating microchannels on PMMA using a CO2 laser, the maximum depth of the fabricated microchannel is the key feature. There are few analytical models available to predict the maximum depth of the microchannels and cut channel profile on PMMA substrate using a CO2 laser. These models depend upon the values of thermophysical properties of PMMA and laser beam parameters. There are a number of variants of transparent PMMA available in the market with different values of thermophysical properties. Therefore, for applying such analytical models, the values of these thermophysical properties are required to be known exactly. Although, the values of laser beam parameters are readily available, extensive experiments are required to be conducted to determine the value of thermophysical properties of PMMA. The unavailability of exact values of these property parameters restrict the proper control over the microchannel dimension for given power and scanning speed of the laser beam. In order to have dimensional control over the maximum depth of fabricated microchannels, it is necessary to have an idea of uncertainty associated with the predicted microchannel depth. In this research work, the uncertainty associated with the maximum depth dimension has been determined using Monte Carlo method (MCM). The propagation of uncertainty with different power and scanning speed has been predicted. The relative impact of each thermophysical property has been determined using sensitivity analysis.

Efficacy and safety of fractional CO2 laser versus fractional Er:YAG laser in the treatment of facial skin wrinkles.

PubMed

Robati, Reza M; Asadi, Elmira

2017-02-01

Ablative fractional lasers were introduced for treating facial rhytides. Few studies have compared fractional CO 2 and Er:YAG lasers on cutaneous photodamages by a split trial. The aim of the present study was to compare these modalities in a randomized controlled double-blind split-face design with multiple sessions and larger sample size compared to previous studies done before. Forty patients with facial wrinkles were enrolled. Patients were randomly assigned to receive three monthly treatments on each side of the face, one with a fractional CO 2 and one with a fractional Er:YAG laser. The evaluations included investigating clinical outcome determined by two independent dermatologists not enrolled in the treatment along with measuring skin biomechanical property of cheeks using a sensitive biometrologic device with the assessment of cutaneous resonance running time (CRRT). Moreover, possible side effects and patients' satisfaction have been recorded at baseline, 1 month after each treatment, and 3 months after the last treatment session. Clinical assessment showed both modalities significantly reduce facial wrinkles (p value < 0.05), with no appreciable difference between two lasers. Mean CRRT values also decreased significantly after the laser treatment compared to the baseline in both laser groups. There was no serious long-standing adverse effect after both laser treatments, but the discomfort was more pronounced by the participants after CO 2 laser treatment. According to the present study, both fractional CO 2 and fractional Er:YAG lasers show considerable clinical improvement of facial skin wrinkles with no serious adverse effects, but post-treatment discomfort seems to be lower with Er:YAG laser.

Dissociation phenomena in electron-beam sustained carbon dioxide lasers

NASA Technical Reports Server (NTRS)

Harris, Michael R.; Willetts, David V.

1990-01-01

A number of applications are emerging requiring efficient, long pulse, long-life sealed CO2 lasers. Examples include the proposed NASA and ESA wind lidars. Electron-beam sustained discharge devices are strong contenders. Unlike self-sustained discharges, e-beam sustenance readily provides efficient performance from large volume discharges and offers pulse lengths well in excess of the microsecond or so generally associated with self-sustained devices. In the case of the e-beam sustained laser, since the plasma is externally maintained and operated at electric field strengths less than that associated with the glow to arc transition, the discharges can be run even in the presence of strongly attacking species such as O2. Build up of large levels of attacking contaminants is nevertheless undesirable as their presence reduces the current drawn by the plasma and thus the pumping rate to the upper laser level. The impedance rise leads to a mismatch of the pulse forming network with a consequent loss of control over energy deposition, operating E/N, and gain. Clearly CO2 dissociation rates, the influence of dissociation products on the discharge and gain, and tolerance of the discharge to these products need to be determined. This information can then be used to assess co-oxidation catalyst requirements for sealed operation.

Evaluation of the effect of fractional CO2 laser on histopathological picture and TGF-β1 expression in hypertrophic scar.

PubMed

Makboul, Mohamed; Makboul, Rania; Abdelhafez, Assem Hk; Hassan, Safaa Said; Youssif, Sherif M

2014-09-01

Hypertrophic scar is a form of abnormal wound healing process in which tissue repair regulating mechanism is disrupted. Transforming growth factor β1 has a particular importance in the fibrotic scarring response. Treatment of hypertrophic scar included many chemical, physical, and surgical options. Fractional CO2 laser devices have gained acceptance as a way for managing hypertrophic scar. Aims of this study are: (a) to determine the clinical and histopathological effects of fractional CO2 laser on hypertrophic scar, (b) to evaluate the expression pattern of transforming growth factor-β1 (TGF-β1) as an important fibrogenic factor before and 6 months after fractional CO2 laser treatment. Forty patients of hypertrophic scar were selected, each patient was treated by four sessions with 1 month apart with fractional CO2 laser. Vancouver Scar Scale (VSS) was used to assess the patients before and after laser treatment. Skin biopsy was taken from eight cases before and 3 months after four fractional CO2 laser sessions and four normal skin control biopsies. All were assessed by hematoxylin-eosin (H&E), Masson's trichrome, Van Gieson and immunohistochemical (IHC) staining with TGF-β1. The epidermal thickness was assessed before and after treatment by image analyzing system software. There was statistically significant difference in VSS before and after fractional CO2 laser (P > 0.001). The epidermal thickness showed significant increase after laser treatment (P > 0.001), and there was also thinning in stratum corneum and replacement of the irregular collagen bands with organized new collagen fibrils as demonstrated by H&E and the other special stains. The study also showed significant decrease in TGF-β1 expression after laser therapy (P = 0.008). Fractional CO2 laser could be considered as a good way for hypertrophic scar management. It normalizes dermal collagen as imaged by histopathological picture and the change in TGF-β1 expression. © 2014 Wiley Periodicals, Inc.

Shifting of infrared radiation using rotational raman resonances in diatomic molecular gases

DOEpatents

Kurnit, Norman A.

1980-01-01

A device for shifting the frequency of infrared radiation from a CO.sub.2 laser by stimulated Raman scattering in either H.sub.2 or D.sub.2. The device of the preferred embodiment comprises an H.sub.2 Raman laser having dichroic mirrors which are reflective for 16 .mu.m radiation and transmittive for 10 .mu.m, disposed at opposite ends of an interaction cell. The interaction cell contains a diatomic molecular gas, e.g., H.sub.2, D.sub.2, T.sub.2, HD, HT, DT and a capillary waveguide disposed within the cell. A liquid nitrogen jacket is provided around the capillary waveguide for the purpose of cooling. In another embodiment the input CO.sub.2 radiation is circularly polarized using a Fresnel rhomb .lambda./4 plate and applied to an interaction cell of much longer length for single pass operation.

Pulsed-discharge carbon dioxide lasers

NASA Technical Reports Server (NTRS)

Willetts, David V.

1990-01-01

The purpose is to attempt a general introduction to pulsed carbon dioxide lasers of the kind used or proposed for laser radar applications. Laser physics is an excellent example of a cross-disciplinary topic, and the molecular spectroscopy, energy transfer, and plasma kinetics of the devices are explored. The concept of stimulated emission and population inversions is introduced, leading on to the molecular spectroscopy of the CO2 molecule. This is followed by a consideration of electron-impact pumping, and the pertinent energy transfer and relaxation processes which go on. Since the devices are plasma pumped, it is necessary to introduce a complex subject, but this is restricted to appropriate physics of glow discharges. Examples of representative devices are shown. The implications of the foregoing to plasma chemistry and gas life are discussed.

Ignition of an automobile engine by high-peak power Nd:YAG/Cr⁴⁺:YAG laser-spark devices.

PubMed

Pavel, Nicolaie; Dascalu, Traian; Salamu, Gabriela; Dinca, Mihai; Boicea, Niculae; Birtas, Adrian

2015-12-28

Laser sparks that were built with high-peak power passively Q-switched Nd:YAG/Cr(4+):YAG lasers have been used to operate a Renault automobile engine. The design of such a laser spark igniter is discussed. The Nd:YAG/Cr(4+):YAG laser delivered pulses with energy of 4 mJ and 0.8-ns duration, corresponding to pulse peak power of 5 MW. The coefficients of variability of maximum pressure (COV(Pmax)) and of indicated mean effective pressure (COV(IMEP)) and specific emissions like hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NO(x)) and carbon dioxide (CO2) were measured at various engine speeds and high loads. Improved engine stability in terms of COV(Pmax) and COV(Pmax) and decreased emissions of CO and HC were obtained for the engine that was run by laser sparks in comparison with classical ignition by electrical spark plugs.

Terminal Deoxynucleotidyl Transferase-Mediated Deoxyuridine Triphosphate Nick End Labeling (TUNEL) Assay to Characterize Histopathologic Changes Following Thermal Injury

PubMed Central

Lee, Ji Min; Park, Ji Hyun; Kim, Bo Young

2018-01-01

Background Despite the wide application of lasers and radiofrequency (RF) surgery in dermatology, it is difficult to find studies showing the extent of damage dependent on cell death. Objective We evaluated histopathologic changes following in vivo thermal damage generated by CO2 laser, 1,444 nm long-pulsed neodymium:yttrium-aluminum-garnet (LP Nd:YAG) laser and RF emitting electrosurgical unit. Methods Thermal damage was induced by the above instruments on ventral skin of rat. Specimens were stained with hematoxylin and eosin, along with a terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling (TUNEL) assay, to highlight the degree of irreversible cellular injury. Results The volume of vaporization was largest with the CO2 laser. Area of cell death area identified by TUNEL assay, when arranged from widest to narrowest, was 1,444 nm LP Nd:YAG laser, CO2 laser, and RF emitting electrosurgical unit. Conclusion This histopathologic evaluation of the acute characterization of injury across devices may be advantageous for attaining better treatment outcomes. PMID:29386831

Removal of dogs' gingival pigmentation with CO2 laser

NASA Astrophysics Data System (ADS)

Figueiredo, Jose A. P.; Chavantes, Maria C.; Gioso, Marco A.; Pesce, Hildeberto F.; Jatene, Adib D.

1995-05-01

The aim of this study was to analyze the ability of CO2 laser to remove physiologic pigmentation of gingiva. Dogs were chosen for this study because of their intense black pigmentation on the gingiva, similar to what can be found in human negroes and other dark- skinned races. Three specimens were irradiated at the left side of the buccal aspect of the gingiva, while for comparison the right side was used as a control. CO2 laser in a continuous mode applying 3 watt power was used (Xanar-20, USA). The portion to be irradiated was continuously irrigated with saline solution, to prevent tissue damage from the excessive heat generated. The handpiece device irradiated the target easily and fast, with no bleeding. All the pigmentation could be removed from the portion exposed to the laser beam. A 45th day follow up showed very little repigmentation just in one of the specimens. It could be concluded that CO2 laser irradiation can be an alternative to remove pigmentation of the gingiva for cosmetic purposes. The risk of repigmentation exists, so the patients should be aware of this inconvenience, sometimes demanding further irradiation.

Laser applications in advanced chip packaging

NASA Astrophysics Data System (ADS)

Müller, Dirk; Held, Andrew; Pätzel, Rainer; Clark, Dave; van Nunen, Joris

2016-03-01

While applications such as drilling μ-vias and laser direct imaging have been well established in the electronics industry, the mobile device industry's push for miniaturization is generating new demands for packaging technologies that allow for further reduction in feature size while reducing manufacturing cost. CO lasers have recently become available and their shorter wavelength allows for a smaller focus and drilling hole diameters down to 25μm whilst keeping the cost similar to CO2 lasers. Similarly, nanosecond UV lasers have gained significantly in power, become more reliable and lower in cost. On a separate front, the cost of ownership reduction for Excimer lasers has made this class of lasers attractive for structuring redistribution layers of IC substrates with feature sizes down to 2μm. Improvements in reliability and lower up-front cost for picosecond lasers is enabling applications that previously were only cost effective with mechanical means or long-pulsed lasers. We can now span the gamut from 100μm to 2μm for via drilling and can cost effectively structure redistribution layers with lasers instead of UV lamps or singulate packages with picosecond lasers.

Flexible Carbon Dioxide Laser Fiber Versus Ultrasonic Scalpel in Robot-Assisted Laparoscopic Myomectomy.

PubMed

Choussein, Souzana; Srouji, Serene S; Farland, Leslie V; Gargiulo, Antonio R

2015-01-01

To compare the effectiveness and safety of a flexible carbon dioxide (CO2) laser fiber to the ultrasonic scalpel when employed through a robotic surgical system. Retrospective cohort study. Level II-2 evidence. Reproductive surgery practice at an academic hospital. Two hundred thirty-six women who had undergone robot-assisted laparoscopic myomectomy with either CO2 laser (n = 85) or the ultrasonic scalpel (n = 151). Robot-assisted laparoscopic myomectomy employing either a flexible CO2 laser fiber or a robotic ultrasonic scalpel as the primary energy tool. Perioperative outcomes (estimated blood loss, operative time, length of hospital stay) of patients undergoing robot-assisted myomectomy with a flexible laser fiber or ultrasonic scalpel. Estimated blood loss and operative time were comparable (p = .95 and p = .55, respectively) between the 2 groups after adjusting for all confounders, whereas length of hospital stay remained significantly different (p = .004). Odds ratio for complications was 0.35 (95% confidence interval 0.08-1.56; p = .17), which denotes no difference in the risk for complications between the 2 groups. Robot-assisted laparoscopic myomectomy with a flexible CO2 laser fiber is safe and has comparable operative outcomes to the ultrasonic scalpel. The small size and flexibility of this device allows robotic surgeons to employ safe focal energy without sacrificing operative ergonomics. Copyright © 2015 AAGL. Published by Elsevier Inc. All rights reserved.

Laser Plasma Heating.

DTIC Science & Technology

The heating of a plasma by a laser is studied, assuming the classical inverse bremsstrahlung mechanism for transfer of energy from laser photons to electron thermal energy. Emphasis is given to CO2 laser heating of the dense plasma focus (DPF) device. Particular attention is paid to the contribution of impurities to the radiation output of the DPF. A steady-state CORONA model is discussed and used to generate a computer program, CORONA, which calculates species densities as a function of electron temperature. (Author)

Easy Debonding of Ceramic Brackets Bonded with a Light-Cured Orthodontic Adhesive Containing Microcapsules with a CO2 Laser.

PubMed

Arima, Shiori; Namura, Yasuhiro; Tamura, Takahiko; Shimizu, Noriyoshi

2018-03-01

An easy debonding method for ceramic brackets using a light-cured Bis-GMA resin containing heat-expandable microcapsules and CO 2 laser was investigated. Ceramic brackets are used frequently in orthodontic treatment because of their desirable esthetic properties. However, the application of heavy force to ceramic brackets in debonding can fracture the tooth enamel and ceramic brackets, causing tooth pain. In total, 60 freshly extracted bovine permanent mandibular incisors were divided randomly into 10 groups of 6 specimens each, corresponding to the number of variables tested. Ceramic brackets were bonded to bovine permanent mandibular incisors using an orthodontic bonding agent containing heat-expandable microcapsules at different levels (0-30 wt%) and resin composite paste, and cured by a curing device. The bond strengths were measured before and after CO 2 laser irradiation, and the temperature increase in the pulp chamber in fresh human first premolars was also evaluated. With CO 2 laser irradiation for 5 sec to the bracket, the bond strength in the 25% microcapsule group decreased significantly, to ∼0.17-fold, compared with that of the no-laser group (p < 0.05). The maximum temperature increase in the pulp chamber was 5.3°C with laser irradiation, which was less than the level that induces pulp damage. From these results, it seems likely that the combined use of a light-cured orthodontic bonding agent containing microcapsules and a CO 2 laser is a simple debonding system for ceramic brackets, with less debonding time and enamel damage.

3D Finite Element Model for Writing Long-Period Fiber Gratings by CO2 Laser Radiation

PubMed Central

Coelho, João M. P.; Nespereira, Marta; Abreu, Manuel; Rebordão, José

2013-01-01

In the last years, mid-infrared radiation emitted by CO2 lasers has become increasing popular as a tool in the development of long-period fiber gratings. However, although the development and characterization of the resulting sensing devices have progressed quickly, further research is still necessary to consolidate functional models, especially regarding the interaction between laser radiation and the fiber's material. In this paper, a 3D finite element model is presented to simulate the interaction between laser radiation and an optical fiber and to determine the resulting refractive index change. Dependence with temperature of the main parameters of the optical fiber materials (with special focus on the absorption of incident laser radiation) is considered, as well as convection and radiation losses. Thermal and residual stress analyses are made for a standard single mode fiber, and experimental results are presented. PMID:23941908

Development of CO2 laser dispersion interferometer with photoelastic modulator

NASA Astrophysics Data System (ADS)

Akiyama, T.; Kawahata, K.; Okajima, S.; Nakayama, K.

2010-10-01

A dispersion interferometer is one of the promising methods of the electron density measurement on large and high density fusion devices. This paper describes development of a CO2 laser dispersion interferometer with a photoelastic modulator for phase modulation. In order to make the dispersion interferometer free from variations of the detected intensity, a new phase extraction method is introduced: The phase shift is evaluated from a ratio of amplitudes of the fundamental and the second harmonics of the phase modulation frequency in the detected interference signal. The proof-of-principle experiments demonstrate the feasibility of this method.

Development of CO2 laser dispersion interferometer with photoelastic modulator.

PubMed

Akiyama, T; Kawahata, K; Okajima, S; Nakayama, K

2010-10-01

A dispersion interferometer is one of the promising methods of the electron density measurement on large and high density fusion devices. This paper describes development of a CO(2) laser dispersion interferometer with a photoelastic modulator for phase modulation. In order to make the dispersion interferometer free from variations of the detected intensity, a new phase extraction method is introduced: The phase shift is evaluated from a ratio of amplitudes of the fundamental and the second harmonics of the phase modulation frequency in the detected interference signal. The proof-of-principle experiments demonstrate the feasibility of this method.

Fast production of microfluidic devices by CO2 laser engraving of wax-coated glass slides.

PubMed

da Costa, Eric T; Santos, Mauro S F; Jiao, Hong; do Lago, Claudimir L; Gutz, Ivano G R; Garcia, Carlos D

2016-07-01

Glass is one of the most convenient materials for the development of microfluidic devices. However, most fabrication protocols require long processing times and expensive facilities. As a convenient alternative, polymeric materials have been extensively used due their lower cost and versatility. Although CO2 laser ablation has been used for fast prototyping on polymeric materials, it cannot be applied to glass devices because the local heating causes thermal stress and results in extensive cracking. A few papers have shown the ablation of channels or thin holes (used as reservoirs) on glass but the process is still far away from yielding functional glass microfluidic devices. To address these shortcomings, this communication describes a simple method to engrave glass-based capillary electrophoresis devices using standard (1 mm-thick) microscope glass slides. The process uses a sacrificial layer of wax as heat sink and enables the development of both channels (with semicircular shape) and pass-through reservoirs. Although microscope images showed some small cracks around the channels (that became irrelevant after sealing the engraved glass layer to PDMS) the proposed strategy is a leap forward in the application of the technology to glass. In order to demonstrate the capabilities of the approach, the separation of dopamine, catechol and uric acid was accomplished in less than 100 s. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Current role of resurfacing lasers.

PubMed

Hantash, B M; Gladstone, H B

2009-06-01

Resurfacing lasers have been the treatment of choice for diminishing rhytids and tightening skin. The carbon dioxide and erbium lasers have been the gold and silver standards. Despite their effectiveness, these resurfacing lasers have a very high risk profile including scarring, hyperpigmentation and hypopigmentation. Because of these side effects, various practitioners have tried alternative settings for these lasers as well as alternative wavelengths, particularly in the infrared spectrum. These devices have had less downtime, but their effectiveness has been limited to fine wrinkles. As with selective photothemolysis, a major advance in the field has been fractionated resurfacing which incorporates grids of microthermal zones that spares islands of skin. This concept permits less tissue damage and quicker tissue regeneration. Initially, fractionated resurfacing was limited to the nonablative mid-infrared spectrum. These resurfacing lasers is appropriate for those patients with acne scars, uneven skin tone, mild to moderate photodamage, and is somewhat effective for melasma. Importantly, because there is less overall tissue damage and stimulation of melanocytes, these lasers can be used in darker skin types. Downtime is 2-4 days of erythema and scaling. Yet, these nonablative fractionated devices required 5-6 treatments to achieve a moderate effect. Logically, the fractionated resurfacing has now been applied to the CO2 and the Erbium:Yag lasers. These devices can treat deeper wrinkles and tighten skin. Downtime appears to be 5-7 days. The long term effectiveness and the question of whether these fractionated devices will approach the efficacy of the standard resurfacing lasers is still in question. Ultimately either integrated devices which may use fractionated resurfacing, radiofrequency and a sensitizer, or combining different lasers in a single treatment may prove to be the most effective in reducing rhtyides, smoothing the skin topography and tightening the skin envelope.

Experimental Investigation of Axial and Beam-Riding Propulsive Physics with TEA CO{sub 2} laser

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

Kenoyer, D. A.; Salvador, I.; Myrabo, L. N.

2010-10-08

A twin Lumonics K922M pulsed TEA CO{sub 2} laser system (pulse duration of approximately 100 ns FWHM spike, with optional 1 {mu}s tail, depending upon laser gas mix) was employed to experimentally measure both axial thrust and beam-riding behavior of Type no. 200 lightcraft engines, using a ballistic pendulum and Angular Impulse Measurement Device (AIMD, respectively. Beam-riding forces and moments were examined along with engine thrust-vectoring behavior, as a function of: a) laser beam lateral offset from the vehicle axis of symmetry; b) laser pulse energy ({approx}12 to 40 joules); c) pulse duration (100 ns, and 1 {mu}s); and d)more » engine size (97.7 mm to 161.2 mm). Maximum lateral momentum coupling coefficients (C{sub M}) of 75 N-s/MJ were achieved with the K922M laser whereas previous PLVTS laser (420 J, 18 {mu}s duration) results reached only 15 N-s/MJ--an improvement of 5x. Maximum axial C{sub M} performance with the K922M reached 225 N-s/MJ, or about {approx}3x larger than the lateral C{sub M} values. These axial C{sub M} results are sharply higher than the 120 N/MW previously reported for long pulse (e.g., 10-18 {mu}s)CO{sub 2} electric discharge lasers.« less

All-optical switching of magnetoresistive devices using telecom-band femtosecond laser

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

He, Li; Chen, Jun-Yang; Wang, Jian-Ping, E-mail: jpwang@umn.edu, E-mail: moli@umn.edu

Ultrafast all-optical switching of the magnetization of various magnetic systems is an intriguing phenomenon that can have tremendous impact on information storage and processing. Here, we demonstrate all-optical switching of GdFeCo alloy films using a telecom-band femtosecond fiber laser. We further fabricate Hall cross devices and electrically readout all-optical switching by measuring anomalous Hall voltage changes. The use of a telecom laser and the demonstrated all-optical switching of magnetoresistive devices represent the first step toward integration of opto-magnetic devices with mainstream photonic devices to enable novel optical and spintronic functionalities.

GaSb-based single-mode distributed feedback lasers for sensing (Conference Presentation)

NASA Astrophysics Data System (ADS)

Gupta, James A.; Bezinger, Andrew; Lapointe, Jean; Poitras, Daniel; Aers, Geof C.

2017-02-01

GaSb-based tunable single-mode diode lasers can enable rapid, highly-selective and highly-sensitive absorption spectroscopy systems for gas sensing. In this work, single-mode distributed feedback (DFB) laser diodes were developed for the detection of various trace gases in the 2-3.3um range, including CO2, CO, HF, H2S, H2O and CH4. The lasers were fabricated using an index-coupled grating process without epitaxial regrowth, making the process significantly less expensive than conventional DFB fabrication. The devices are based on InGaAsSb/AlGaAsSb separate confinement heterostructures grown on GaSb by molecular beam epitaxy. DFB lasers were produced using a two step etch process. Narrow ridge waveguides were first defined by optical lithography and etched into the semiconductor. Lateral gratings were then defined on both sides of the ridge using electron-beam lithography and etched to produce the index-grating. Effective index modeling was used to optimize the ridge width, etch depths and the grating pitch to ensure single-lateral-mode operation and adequate coupling strength. The effective index method was further used to simulate the DFB laser emission spectrum, based on a transfer matrix model for light transmission through the periodic structure. The fabricated lasers exhibit single-mode operation which is tunable through the absorption features of the various target gases by adjustment of the drive current. In addition to the established open-path sensing applications, these devices have great potential for optoelectronic integrated gas sensors, making use of integrated photodetectors and possibly on-chip Si photonics waveguide structures.

Cosmetic and aesthetic skin photosurgery using a computer-assisted CO2 laser-scanning system

NASA Astrophysics Data System (ADS)

Dutu, Doru C. A.; Dumitras, Dan C.; Nedelcu, Ioan; Ghetie, Sergiu D.

1997-12-01

Since the first application of CO2 laser in skin photosurgery, various techniques such as laser pulsing, beam scanning and computer-assisted laser pulse generator have been introduced for the purpose of reducing tissue carbonization and thermal necrosis. Using a quite simple XY optical scanner equipped with two galvanometric driven mirrors and an appropriate software to process the scanning data and control the interaction time and energy density in the scanned area, we have obtained a device which can improve CO2 laser application in cosmetic and aesthetic surgery. The opto-mechanical CO2 laser scanner based on two total reflecting flat mirrors placed at 90 degree(s) in respect to the XY scanning directions and independently driven through a magnetic field provides a linear movement of the incident laser beam in the operating field. A DA converter supplied with scanning data by the software enables a scanning with linearity better than 1% for a maximum angular deviation of 20 degree(s). Because the scanning quality of the laser beam in the operating field is given not only by the displacement function of the two mirrors, but also by the beam characteristics in the focal plane and the cross distribution in the laser beam, the surgeon can control through software either the scanning field dimensions or the distance between two consecutive points of the vertically and/or horizontally sweep line. The development of computer-assisted surgical scanning techniques will help control the surgical laser, to create either a reproducible incision with a controlled depth or a controlled incision pattern with minimal incision width, a long desired facility for plastic surgery, neurosurgery, ENT and dentistry.

Investigation of SOI Raman Lasers for Mid-Infrared Gas Sensing

PubMed Central

Passaro, Vittorio M.N.; De Leonardis, Francesco

2009-01-01

In this paper, the investigation and detailed modeling of a cascaded Raman laser, operating in the midwave infrared region, is described. The device is based on silicon-on-insulator optical waveguides and a coupled resonant microcavity. Theoretical results are compared with recent experiments, demonstrating a very good agreement. Design criteria are derived for cascaded Raman lasers working as continuous wave light sources to simultaneously sense two types of gases, namely C2H6 and CO2, at a moderate power level of 130 mW. PMID:22408481

Influence of Selective Laser Melting Processing Parameters of Co-Cr-W Powders on the Roughness of Exterior Surfaces

NASA Astrophysics Data System (ADS)

Baciu, M. A.; Baciu, E. R.; Bejinariu, C.; Toma, S. L.; Danila, A.; Baciu, C.

2018-06-01

Selective Laser Melting (SLM) represents an Additive Manufacturing method widely used in medical practice, mainly in dental medicine. The powder of 59% Co, 25% Cr, 2.5% W alloy (Starbond CoS Powder 55, S&S Scheftner C, Germany) was processed (SLM) on a Realizer SLM 50 device (SLM Solution, Germany). After laser processing and simple sanding with Al2O3 or two-phase sanding (Al2O3 and glass balls), measurements of surface roughness were conducted. This paper presents the influences exercised by laser power (P = 60 W, 80 W and 100 W), the scanning speed (vscan = 333 mm/s, 500 mm/s and 1000 mm/s) and exposure time (te = 20 µs, 40 µs and 60 µs) on the roughness of surfaces obtained by SLM processing. Based on the experimental results obtained for roughness (Ra), some recommendations regarding the choice of favorable combinations among the values of technological parameters under study in order to obtain the surface quality necessary for subsequent applications of the processed parts (SLM) have been made.

Dual-Pump Coherent Anti-Stokes Raman Scattering Temperature and CO2 Concentration Measurements

NASA Technical Reports Server (NTRS)

Lucht, Robert P.; Velur-Natarajan, Viswanathan; Carter, Campbell D.; Grinstead, Keith D., Jr.; Gord, James R.; Danehy, Paul M.; Fiechtner, G. J.; Farrow, Roger L.

2003-01-01

Measurements of temperature and CO2 concentration using dual-pump coherent anti-Stokes Raman scattering, (CARS) are described. The measurements were performed in laboratory flames,in a room-temperature gas cell, and on an engine test stand at the U.S. Air Force Research Laboratory, Wright-Patterson Air Force Base. A modeless dye laser, a single-mode Nd:YAG laser, and an unintensified back-illuminated charge-coupled device digital camera were used for these measurements. The CARS measurements were performed on a single-laser-shot basis. The standard deviations of the temperatures and CO2 mole fractions determined from single-shot dual-pump CARS spectra in steady laminar propane/air flames were approximately 2 and 10% of the mean values of approximately 2000 K and 0.10, respectively. The precision and accuracy of single-shot temperature measurements obtained from the nitrogen part of the dual-pump CARS system were investigated in detail in near-adiabatic hydrogen/air/CO2 flames. The precision of the CARS temperature measurements was found to be comparable to the best results reported in the literature for conventional two-laser, single-pump CARS. The application of dual-pump CARS for single-shot measurements in a swirl-stabilized combustor fueled with JP-8 was also demonstrated.

Laser-induced porous graphene films from commercial polymers

NASA Astrophysics Data System (ADS)

Lin, Jian; Peng, Zhiwei; Liu, Yuanyue; Ruiz-Zepeda, Francisco; Ye, Ruquan; Samuel, Errol L. G.; Yacaman, Miguel Jose; Yakobson, Boris I.; Tour, James M.

2014-12-01

The cost effective synthesis and patterning of carbon nanomaterials is a challenge in electronic and energy storage devices. Here we report a one-step, scalable approach for producing and patterning porous graphene films with three-dimensional networks from commercial polymer films using a CO2 infrared laser. The sp3-carbon atoms are photothermally converted to sp2-carbon atoms by pulsed laser irradiation. The resulting laser-induced graphene (LIG) exhibits high electrical conductivity. The LIG can be readily patterned to interdigitated electrodes for in-plane microsupercapacitors with specific capacitances of >4 mF cm-2 and power densities of ~9 mW cm-2. Theoretical calculations partially suggest that enhanced capacitance may result from LIG’s unusual ultra-polycrystalline lattice of pentagon-heptagon structures. Combined with the advantage of one-step processing of LIG in air from commercial polymer sheets, which would allow the employment of a roll-to-roll manufacturing process, this technique provides a rapid route to polymer-written electronic and energy storage devices.

Laser-induced porous graphene films from commercial polymers

PubMed Central

Lin, Jian; Peng, Zhiwei; Liu, Yuanyue; Ruiz-Zepeda, Francisco; Ye, Ruquan; Samuel, Errol L. G.; Yacaman, Miguel Jose; Yakobson, Boris I.; Tour, James M.

2014-01-01

Synthesis and patterning of carbon nanomaterials cost effectively is a challenge in electronic and energy storage devices. Here report a one-step, scalable approach for producing and patterning porous graphene films with 3-dimensional networks from commercial polymer films using a CO2 infrared laser. The sp3-carbon atoms are photothermally converted to sp2-carbon atoms by pulsed laser irradiation. The resulting laser-induced graphene (LIG) exhibits high electrical conductivity. The LIG can be readily patterned to interdigitated electrodes for in-plane microsupercapacitors with specific capacitances of >4 mF·cm−2 and power densities of ~9 mW·cm−2. Theoretical calculations partially suggest that enhanced capacitance may result from LIG’s unusual ultra-polycrystalline lattice of pentagon-heptagon structures. Combined with the advantage of one-step processing of LIG in air from commercial polymer sheets, which would allow the employment of a roll-to-roll manufacturing process, this technique provides a rapid route to polymer-written electronic and energy storage devices. PMID:25493446

High Power OPO Laser and wavelength-controlled system for 1.6μm CO2-DIAL

NASA Astrophysics Data System (ADS)

Abo, M.; Nagasawa, C.; Shibata, Y.

2009-12-01

Unlike the existing 2.0μm CO2-DIAL, a high-energy pulse laser operating in the 1.6μm absorption band of CO2 has not been realized. Quasi phase matching (QPM) devices have high conversion efficiency and high beam quality due to their higher nonlinear optical coefficient. We adapt the PPMgLT crystal as the QPM device. The PPMgLT crystal had 3mm × 3mm apertures, and the periodically poled period was 30.9 μm, with the duty ratio close to the ideal value of 0.5. The beam quality of the pumping laser was exceed M2 ≥1.2. The repetition rate was 400 Hz and the energy was 35 mJ. The pumping laser pulse was injection-seeded by the continuous-wave (CW) fiber laser, which had a narrow spectrum. The pulse pumped the PPMgLT crystal in the ring cavity with a single pass through the dielectric mirror. The PPMgLT crystal was mounted on a copper holder, and the temperature was maintained at 40 °C using a Peltier module. The holder’s temperature was stabilized to within 0.01 °C when the copper holder was covered with a plastic case. The OPO ring cavity was a singly resonant oscillator optimized for the signal wave. Single-frequency oscillation of the PPMgLT OPO was achieved by injection seeding, as described in the following. The injection seeder was a DFB laser having a power of 30mW with a 1MHz oscillation spectrum. Their oscillation wavelength was coarse tuned by temperature and fine tuned by adjusting injection currents. The partial power of the online wavelength was split in the wavelength control unit. We locked the DFB laser as an injection seeder of the online wavelength onto the line center by referencing the fiber coupled multipath gas cell (path length 800mm) containing pure CO2 at a pressure of 700 Torr. Stabilization was estimated to within 1.8MHz rms of the line center of the CO2 absorption line by monitoring the feedback signal of a wavelength-controlled unit. Injection seeding of the PPMgLT OPO was performed by matching the cavity length to the seeder wavelength for each oscillation pulse. The on-line and off-line wavelengths were injected into the OPO cavity through its output mirror. The injection seeder could be automatically switched by applying the TTL trigger to an optical fiber switch. A typical power of 8mW was injected into the cavity. The OPO cavity length was controlled as follows. A slope voltage was applied to the piezoelectric element mounted on the cavity mirror. If the longitudinal mode of the cavity was closed at the wavelength of the injection seeder, the electrical signal monitored by the photodiode would be maximized. The CW laser beam was injected from the output coupler to control the oscillation wavelength. The maximum output energy of 12mJ at 400 Hz was observed at 35mJ of pumping laser energy. The slope efficiency was 43.7%. This output energy and this repetition rate were the highest achieved so far. No damage was observed even after 1 h of operation. Therefore higher-energy operations can be expected with this device if the beam quality of the pumping laser is improved. This work was financially supported by the System Development Program for Advanced Measurement and Analysis by the JST.

Portable fiber-coupled diode-laser-based sensor for multiple trace gas detection

NASA Technical Reports Server (NTRS)

Lancaster, D. G.; Richter, D.; Tittel, F. K.

1999-01-01

Tunable narrowband mid-infrared radiation from 3.25 to 4.4 micrometers is generated by a compact fiber-coupled, difference-frequency-based spectroscopic source. A 20-mW external cavity diode laser (with a tuning range from 814 to 870 nm) and a 50-mW distributed-Bragg-reflector diode-laser-seeded ytterbium-doped fiber amplifier operating at 1083 nm are difference-frequency mixed in a multi-grating, temperature-controlled periodically poled LiNbO3 crystal. A conversion efficiency of 0.44 mW/(W2cm) (corresponding to a power of approximately equal to 3 microW at 3.3 micrometers) represents the highest conversion efficiency reported for a portable device. Performance characteristics of such a sensor and its application to spectroscopic detection of CO2, N2O, H2CO, HCl, NO2, and CH4 will be reported in this work.

Review of the frequency stabilization of TEA CO2 laser oscillators

NASA Technical Reports Server (NTRS)

Willetts, David V.

1987-01-01

Most applications of TEA CO2 lasers in heterodyne radar systems require that the transmitter has a high degree of frequency stability. This ensures good Doppler resolution and maximizes receiver sensitivity. However, the environment within the device is far from benign with fast acoustic and electrical transients being present. Consequently the phenomena which govern the frequency stability of pulsed lasers are quite different from those operative in their CW counterparts. This review concentrates on the mechanisms of chirping within the output pulse; pulse to pulse frequency drift may be eliminated by frequency measurement and correction on successive pulses. It emerges that good stability hinges on correct cavity design. The energy-dependent laser-induced frequency sweep falls dramatically as mode diameter is increased. Thus, it is necessary to construct resonators with good selectivity for single mode operation while having a large spot size.

Transparent, flexible, and high-performance supercapacitor based on ultrafine nickel cobaltite nanospheres

NASA Astrophysics Data System (ADS)

Liu, Xinyue; Wang, Jianxing; Yang, Guowei

2017-07-01

There has been growing interest in transparent and flexible electronic devices such as wrist watch, cell phone, and so on. These devices need the power sources which also have transparent and flexible features. Here, we demonstrate a transparent and flexible energy storage device with outstanding electrochemical performance, high energy density, and super-long life based on ultrafine NiCo2O4 nanospheres which are synthesized by an innovative method concerning laser ablation in liquid and hydrothermal process. The ultrafine NiCo2O4 nanospheres provide high electrochemical activity and the synthesized colloidal solution is suitable for transparent devices. The transparent and flexible device shows a high specific capacitance of 299.7 F/g at the scan rate of 1 mV/s and a long cycling life of 90.4% retention rate after 10,000 cycles at a scan rate of 10 mV/s, which is superior to that of previously reported transparent and flexible energy storage device. In addition, an optical transmittance up to 55% at the wavelength of 550 nm is obtained, and the bending test shows that the bending angle makes no difference to the specific capacitance of the device. In addition, it shows an outstanding energy density of 10.41 Wh/kg. The integrated electrochemical performances of the device are good based on NiCo2O4 nanospheres. These findings make the ultrafine NiCo2O4 nanospheres being promising electrode materials for transparent and flexible energy storage devices.

A laser-based technology for fabricating a soda-lime glass based microfluidic device for circulating tumour cell capture.

PubMed

Nieto, Daniel; Couceiro, Ramiro; Aymerich, Maria; Lopez-Lopez, Rafael; Abal, Miguel; Flores-Arias, María Teresa

2015-10-01

We developed a laser-based technique for fabricating microfluidic microchips on soda-lime glass substrates. The proposed methodology combines a laser direct writing, as a manufacturing tool for the fabrication of the microfluidics structures, followed by a post-thermal treatment with a CO2 laser. This treatment will allow reshaping and improving the morphological (roughness) and optical qualities (transparency) of the generated microfluidics structures. The use of lasers commonly implemented for material processing makes this technique highly competitive when compared with other glass microstructuring approaches. The manufactured chips were tested with tumour cells (Hec 1A) after being functionalized with an epithelial cell adhesion molecule (EpCAM) antibody coating. Cells were successfully arrested on the pillars after being flown through the device giving our technology a translational application in the field of cancer research. Copyright © 2015 Elsevier B.V. All rights reserved.

Feasibility of a Novel Optoacoustic Device to Precisely Localize Endotracheal Tube Positioning in a Cadaver Model

DTIC Science & Technology

2016-11-02

million per year to U.S. hospitals [1,2]. Current methods of assessing ETT position include chest radiography, end- tidal carbon dioxide (EtCO2...lasers to generate sound waves to determine the position of “labeled” ETTs within millimeters of accuracy. Laser optoacoustic imaging combines the merits...of optical tomography (high optical contrast) and ultrasound imaging (minimal scattering of acoustic waves ) to yield high contrast, sensitivity, and

Functional and Physical Outcomes following Use of a Flexible CO2 Laser Fiber and Bipolar Electrocautery in Close Proximity to the Rat Sciatic Nerve with Correlation to an In Vitro Thermal Profile Model

PubMed Central

Robinson, A. M.; Fishman, A. J.; Bendok, B. R.; Richter, C.-P.

2015-01-01

This study compared functional and physical collateral damage to a nerve when operating a Codman MALIS Bipolar Electrosurgical System CMC-III or a CO2 laser coupled to a laser, with correlation to an in vitro model of heating profiles created by the devices in thermochromic ink agarose. Functional damage of the rat sciatic nerve after operating the MALIS or CO2 laser at various power settings and proximities to the nerve was measured by electrically evoked nerve action potentials, and histology of the nerve was used to assess physical damage. Thermochromic ink dissolved in agarose was used to model the spatial and temporal profile of the collateral heating zone of the electrosurgical system and the laser ablation cone. We found that this laser can be operated at 2 W directly above the nerve with minimal damage, while power settings of 5 W and 10 W resulted in acute functional and physical nerve damage, correlating with the maximal heating cone in the thermochromic ink model. MALIS settings up to 40 (11 W) did not result in major functional or physical nerve damage until the nerve was between the forceps tips, correlating with the hottest zone, localized discretely between the tips. PMID:25699266

Device and method for separating oxygen isotopes

DOEpatents

Rockwood, Stephen D.; Sander, Robert K.

1984-01-01

A device and method for separating oxygen isotopes with an ArF laser which produces coherent radiation at approximately 193 nm. The output of the ArF laser is filtered in natural air and applied to an irradiation cell where it preferentially photodissociates molecules of oxygen gas containing .sup.17 O or .sup.18 O oxygen nuclides. A scavenger such as O.sub.2, CO or ethylene is used to collect the preferentially dissociated oxygen atoms and recycled to produce isotopically enriched molecular oxygen gas. Other embodiments utilize an ArF laser which is narrowly tuned with a prism or diffraction grating to preferentially photodissociate desired isotopes. Similarly, desired mixtures of isotopic gas can be used as a filter to photodissociate enriched preselected isotopes of oxygen.

One-step patterning of hollow microstructures in paper by laser cutting to create microfluidic analytical devices.

PubMed

Nie, Jinfang; Liang, Yuanzhi; Zhang, Yun; Le, Shangwang; Li, Dunnan; Zhang, Songbai

2013-01-21

In this paper, we report a simple, low-cost method for rapid, highly reproductive fabrication of paper-based microfluidics by using a commercially available, minitype CO(2) laser cutting/engraving machine. This method involves only one operation of cutting a piece of paper by laser according to a predesigned pattern. The hollow microstructures formed in the paper are used as the 'hydrophobic barriers' to define the hydrophilic flowing paths. A typical paper device on a 4 cm × 4 cm piece of paper can be fabricated within ∼7-20 s; it is ready for use once the cutting process is finished. The main fabrication parameters such as the applied current and cutting rate of the laser were optimized. The fabrication resolution and multiplexed analytical capability of the hollow microstructure-patterned paper were also characterized.

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.

Development of a Dual-Laser Digital Holography Diagnostic for Surface Characterization at ORNL

NASA Astrophysics Data System (ADS)

Sawyer, J. C.; Biewer, T. M.; Thomas, C. E.; Zhang, Z.

2017-10-01

The Fusion and Materials for Nuclear Systems Division (FMNSD) at Oak Ridge National Laboratory (ORNL), in collaboration with The University of Tennessee, Knoxville and Third Dimension Technologies (TDT), presents continuing progress towards the development of a dual-laser digital holography (DH) technique for 3D imaging of plasma facing component (PFC) surfaces in real time. This update includes results from an ``on the bench'' single-laser DH demonstration. The dual-laser approach utilizes two CO2 lasers tuned to neighboring molecular CO2 lines to extend the 2 π ambiguity of holographic interferograms to 5 mm from the 10 μm wavelength. Reconstruction of the interferogram allows for measurement of changes in surface topology at rates of 2 mm/s. This status of a dual-laser DH system ``on the bench,'' demonstration and implementation on the Proto-MPEX device will be presented. This work was supported by The University of Tennessee JDRD program and the US. D.O.E. contract DE-AC05-00OR22725. Research sponsored by the Laboratory Directed Research and Development Program of ORNL, managed by UT Battelle, LLC, for the U.S. D.O.E.

Laser microjoining of dissimilar and biocompatible materials

NASA Astrophysics Data System (ADS)

Bauer, Ingo; Russek, Ulrich A.; Herfurth, Hans J.; Witte, Reiner; Heinemann, Stefan; Newaz, Golam; Mian, A.; Georgiev, D.; Auner, Gregory W.

2004-07-01

Micro-joining and hermetic sealing of dissimilar and biocompatible materials is a critical issue for a broad spectrum of products such as micro-electronics, micro-optical and biomedical products and devices. Today, biocompatible titanium is widely applied as a material for orthopedic implants as well as for the encapsulation of implantable devices such as pacemakers, defibrillators, and neural stimulator devices. Laser joining is the process of choice to hermetically seal such devices. Laser joining is a contact-free process, therefore minimizing mechanical load on the parts to be joined and the controlled heat input decreases the potential for thermal damage to the highly sensitive components. Laser joining also offers flexibility, shorter processing time and higher quality. However, novel biomedical products, in particular implantable microsystems currently under development, pose new challenges to the assembly and packaging process based on the higher level of integration, the small size of the device's features, and the type of materials and material combinations. In addition to metals, devices will also include glass, ceramic and polymers as biocompatible building materials that must be reliably joined in similar and dissimilar combinations. Since adhesives often lack long-term stability or do not meet biocompatibility requirements, new joining techniques are needed to address these joining challenges. Localized laser joining provides promising developments in this area. This paper describes the latest achievements in micro-joining of metallic and non-metallic materials with laser radiation. The focus is on material combinations of metal-polymer, polymer-glass, metal-glass and metal-ceramic using CO2, Nd:YAG and diode laser radiation. The potential for applications in the biomedical sector will be demonstrated.

Prospects for quantum cascade lasers as transmitters and local oscillators in coherent terahertz transmitter/receiver systems

NASA Astrophysics Data System (ADS)

Waldman, Jerry; Danylov, Andriy A.; Goyette, Thomas M.; Coulombe, Michael J.; Giles, Robert H.; Gatesman, Andrew J.; Goodhue, William D.; Li, Jin; Linden, Kurt J.; Nixon, William E.

2009-02-01

Coherent terahertz radar systems, using CO2 laser-pumped molecular lasers have been used during the past decade for radar scale modeling applications, as well as proof-of-principle demonstrations of remote detection of concealed weapons. The presentation will consider the potential for replacement of molecular laser sources by quantum cascade lasers. While the temporal and spatial characteristics of current THz QCLs limit their applicability, rapid progress is being made in resolving these issues. Specifications for satisfying the requirements of coherent short-range THz radars will be reviewed and the feasibility of incorporating existing QCL devices into such systems will be described.

CO2 lasers and applications II; Proceedings of the Third European Congress on Optics, The Hague, Netherlands, Mar. 12-14, 1990

NASA Technical Reports Server (NTRS)

Opower, Hans (Editor)

1990-01-01

Recent advances in CO2 laser technology and its applications are examined. Topics discussed include the excitation of CO2 lasers by microwave discharge, a compact RF-excited 12-kW CO2 laser, a robotic laser for three-dimensional cutting and welding, three-dimensional CO2-laser material processing with gantry machine systems, and a comparison of hollow metallic waveguides and optical fibers for transmitting CO2-laser radiation. Consideration is given to an aerodynamic window with a pump cavity and a supersonic jet, cutting and welding Al using a high-repetition-rate pulsed CO2 laser, speckle reduction in CO2 heterodyne laser radar systems, high-power-laser float-zone crystal growth, melt dynamics in surface processing with laser radiation, laser hardfacing, surface melting of AlSi10Mg with CO2 laser radiation, material processing with Cu-vapor lasers, light-induced flow at a metal surface, and absorption measurements in high-power CW CO2-laser processing of materials.

Welding with the thin disc laser: new processing and application potentials

NASA Astrophysics Data System (ADS)

Hügel, H.; Ruβ, A.; Weberpals, J.; Dausinger, F.

2005-09-01

Thin disc lasers represent a new class of welding lasers in that they combine the beneficial characteristics of CO2- and Nd:YAG-lasers. Their good focusability--values of M2 around 20 are typical for devices in the multi kW power range--can be utilized in several ways to improve the welding performance: compared to lamp-pumped Nd:YAG-lasers, the laser power required at the threshold to the deep penetration regime can be reduced, the welding depth can be increased and far higher values of traverse speed are applicable at prescribed welding depths. Alternatively, the high beam quality allows the use of focusing optics with large focal lengths, hence enabling the realization of "remote welding" concepts. At the same time, a wavelength of 1.03 μm (Yb:YAG) provides, in comparison to CO2-lasers, a high absorptivity at metallic workpieces and a low sensitivity against plasma production; both effects contribute to the efficiency, stability and achievable quality of the welding process. Further, beam delivery via flexible glass fibers with core diameters of 100 μm to 150 μm is possible. With these features and an overall (plug) efficiency of more than 20 %, this laser offers a large potential for many applications.

Laser focus compensating sensing and imaging device

DOEpatents

Vann, Charles S.

1993-01-01

A laser focus compensating sensing and imaging device permits the focus of a single focal point of different frequency laser beams emanating from the same source point. In particular it allows the focusing of laser beam originating from the same laser device but having differing intensities so that a low intensity beam will not convert to a higher frequency when passing through a conversion crystal associated with the laser generating device. The laser focus compensating sensing and imaging device uses a cassegrain system to fold the lower frequency, low intensity beam back upon itself so that it will focus at the same focal point as a high intensity beam. An angular tilt compensating lens is mounted about the secondary mirror of the cassegrain system to assist in alignment. In addition cameras or CCD's are mounted with the primary mirror to sense the focused image. A convex lens is positioned co-axial with the cassegrain system on the side of the primary mirror distal of the secondary for use in aligning a target with the laser beam. A first alternate embodiment includes a cassegrain system using a series of shutters and an internally mounted dichroic mirror. A second alternate embodiment uses two laser focus compensating sensing and imaging devices for aligning a moving tool with a work piece.

Laser focus compensating sensing and imaging device

DOEpatents

Vann, C.S.

1993-08-31

A laser focus compensating sensing and imaging device permits the focus of a single focal point of different frequency laser beams emanating from the same source point. In particular it allows the focusing of laser beam originating from the same laser device but having differing intensities so that a low intensity beam will not convert to a higher frequency when passing through a conversion crystal associated with the laser generating device. The laser focus compensating sensing and imaging device uses a Cassegrain system to fold the lower frequency, low intensity beam back upon itself so that it will focus at the same focal point as a high intensity beam. An angular tilt compensating lens is mounted about the secondary mirror of the Cassegrain system to assist in alignment. In addition cameras or CCD's are mounted with the primary mirror to sense the focused image. A convex lens is positioned co-axial with the Cassegrain system on the side of the primary mirror distal of the secondary for use in aligning a target with the laser beam. A first alternate embodiment includes a Cassegrain system using a series of shutters and an internally mounted dichroic mirror. A second alternate embodiment uses two laser focus compensating sensing and imaging devices for aligning a moving tool with a work piece.

Optical Breath Gas Extravehicular Activity Sensor for the Advanced Portable Life Support System

NASA Technical Reports Server (NTRS)

Wood, William R.; Casias, Miguel E.; Pilgrim, Jeffrey S.; Chullen, Cinda; Campbell, Colin

2016-01-01

The infrared gas transducer used during extravehicular activity (EVA) in the extravehicular mobility unit (EMU) measures and reports the concentration of carbon dioxide (CO2) in the ventilation loop. It is nearing its end of life and there are a limited number remaining. Meanwhile, the next generation advanced portable life support system (PLSS) now being developed requires CO2 sensing technology with performance beyond that presently in use. A laser diode (LD) spectrometer based on wavelength modulation spectroscopy (WMS) is being developed to address both applications by Vista Photonics, Inc. Accommodation within space suits demands that optical sensors meet stringent size, weight, and power requirements. Version 1.0 devices were delivered to NASA Johnson Space Center (JSC) in 2011. The sensors incorporate a laser diode based CO2 channel that also includes an incidental water vapor (humidity) measurement. The prototypes are controlled digitally with a field-programmable gate array (FPGA)/microcontroller architecture. Version 2.0 devices with improved electronics and significantly reduced wetted volumes were delivered to JSC in 2012. A version 2.5 upgrade recently implemented wavelength stabilized operation, better humidity measurement, and much faster data analysis/reporting. A wholly reconfigured version 3.0 will maintain the demonstrated performance of earlier versions while being backwards compatible with the EMU and offering a radiation tolerant architecture.

Studies on third-order optical nonlinearity and power limiting of conducting polymers using the z-scan technique for nonlinear optical applications

NASA Astrophysics Data System (ADS)

Pramodini, S.; Sudhakar, Y. N.; SelvaKumar, M.; Poornesh, P.

2014-04-01

We present the synthesis and characterization of third-order optical nonlinearity and optical limiting of the conducting polymers poly (aniline-co-o-anisidine) and poly (aniline-co-pyrrole). Nonlinear optical studies were carried out by employing the z-scan technique using a He-Ne laser operating in continuous wave mode at 633 nm. The copolymers exhibited a reverse saturable absorption process and self-defocusing properties under the experimental conditions. The estimated values of βeff, n2 and χ(3) were found to be of the order of 10-2 cm W-1, 10-5 esu and 10-7 esu respectively. Self-diffraction rings were observed due to refractive index change when exposed to the laser beam. The copolymers possess a lower limiting threshold and clamping level, which is essential to a great extent for power limiting devices. Therefore, copolymers of aniline emerge as a potential candidate for nonlinear optical device applications.

Screening of inorganic wide-bandgap p-type semiconductors for high performance hole transport layers in organic photovoltaic devices

NASA Astrophysics Data System (ADS)

Ginley, David; Zakutayev, Andriy; Garcia, Andreas; Widjonarko, Nicodemus; Ndione, Paul; Sigdel, Ajaya; Parilla, Phillip; Olson, Dana; Perkins, John; Berry, Joseph

2011-03-01

We will report on the development of novel inorganic hole transport layers (HTL) for organic photovoltaics (OPV). All the studied materials belong to the general class of wide-bandgap p-type oxide semiconductors. Potential candidates suitable for HTL applications include SnO, NiO, Cu2O (and related CuAlO2, CuCrO2, SrCu2O4 etc) and Co3O4 (and related ZnCo2O4, NiCo2O4, MgCo2O4 etc.). Materials have been optimized by high-throughput combinatorial approaches. The thin films were deposited by RF sputtering and pulsed laser deposition at ambient and elevated temperatures. Performance of the inorganic HTLs and that of the reference organic PEDOT:PSS HTL were compared by measuring the power conversion efficiencies and spectral responses of the P3HT/PCBM- and PCDTBT/PCBM-based OPV devices. Preliminary results indicate that Co3O4-based HTLs have performance comparable to that of our previously reported NiOs and PEDOT:PSS HTLs, leading to a power conversion efficiency of about 4 percent. The effect of composition and work function of the ternary materials on their performance in OPV devices is under investigation.

Hypertrophic Scarring of the Neck Following Ablative Fractional Carbon Dioxide Laser Resurfacing

PubMed Central

Avram, Mathew M.; Tope, Whitney D.; Yu, Thomas; Szachowicz, Edward; Nelson, J. Stuart

2009-01-01

Background Ablative fractional carbon dioxide (CO2) laser treatments have gained popularity due to their efficacy, shortened downtime, and decreased potential for scarring in comparison to traditional ablative CO2 resurfacing. To date, scarring with fractional CO2 lasers has not been reported. Objective Five patients treated with the same fractional CO2 laser technology for photodamage of the neck were referred to our practices 1–3 months after treatment. Each patient developed scarring. Of the five cases, two are discussed in detail. The first was treated under general anesthesia on the face and anterior neck at a pulse energy of 30 mJ (859 μm depth) with 25% coverage. Eleven days after treatment, three non-healing areas along the horizontal skin folds of the anterior neck were noted. At 2 weeks after CO2 ablative fractional resurfacing, these areas had become thickened. These raised areas were treated with a non-ablative fractionated 1,550 nm laser to modify the wound healing milieu. One week later, distinct firm pale papules in linear arrays with mild hypopigmentation had developed along involved neck skin folds. Skin biopsy was performed. For the second patient, the neck was treated at a pulse energy of 20 mJ (630 μm depth) with 30% coverage of the exposed skin, with a total treatment energy of 5.0 kJ. Minimal crusting was noted on the neck throughout the initial healing phase of 2 weeks. She then experienced tightness on her neck. Approximately 3 weeks after treatment, she developed multiple vertical and horizontal hypertrophic scars (HS). Results Histopathology for the first case confirmed the presence of a hypertrophic scar. The papules in this case completely resolved with mild residual hypopigmentation after treatment with topical corticosteroids. HS failed to resolve in the second case to date after 1 month. Conclusion As with traditional ablative CO2 laser resurfacing, HS is a potential complication of ablative fractional CO2 laser resurfacing, particularly on the neck. With early diagnosis and appropriate treatment HS of neck skin may be reversible. We urge caution when treating the neck with this device and close attention to wound care in the post-operative period. PMID:19291746

Low loss fusion splicing of micron scale silica fibers.

PubMed

Pal, Parama; Knox, Wayne H

2008-07-21

Tapered micron-sized optical fibers may be important in the future for development of microscale integrated photonic devices. Complex photonic circuits require many devices and a robust technique for interconnection. We demonstrate splicing of four micron diameter step-index air-clad silica microfibers using a CO2 laser. We obtain splice losses lower than 0.3%. Compared with evanescent coupling of microfibers, our splices are more mechanically stable and efficient.

Microsecond enamel ablation with 10.6μm CO2 laser radiation

NASA Astrophysics Data System (ADS)

Góra, W. S.; McDonald, A.; Hand, D. P.; Shephard, J. D.

2016-02-01

Lasers have been previously been used for dental applications, however there remain issues with thermally-induced cracking. In this paper we investigate the impact of pulse length on CO2 laser ablation of human dental enamel. Experiments were carried in vitro on molar teeth without any modification to the enamel surface, such as grinding or polishing. In addition to varying the pulse length, we also varied pulse energy and focal position, to determine the most efficient ablation of dental hard tissue and more importantly to minimize or eradicate cracking. The maximum temperature rise during the multi pulse ablation process was monitored using a set of thermocouples embedded into the pulpal chamber. The application of a laser device in dental surgery allows removal of tissue with higher precision, which results in minimal loss of healthy dental tissue. In this study we use an RF discharge excited CO2 laser operating at 10.6μm. The wavelength of 10.6 μm overlaps with a phosphate band (PO3-4) absorption in dental hard tissue hence the CO2 laser radiation has been selected as a potential source for modification of the tissue. This research describes an in-depth analysis of single pulse laser ablation. To determine the parameters that are best suited for the ablation of hard dental tissue without thermal cracking, a range of pulse lengths (10-200 μs), and fluences (0-100 J/cm2) are tested. In addition, different laser focusing approaches are investigated to select the most beneficial way of delivering laser radiation to the surface (divergent/convergent beam). To ensure that these processes do not increase the temperature above the critical threshold and cause the necrosis of the tissue a set of thermocouples was placed into the pulpal chambers. Intermittent laser radiation was investigated with and without application of a water spray to cool down the ablation site and the adjacent area. Results show that the temperature can be kept below the critical threshold either by using water spray or by decreasing the repetition rate. We demonstrate that CO2 laser pulses with pulse lengths in the regime of 10 μs can provide precise enamel tissue removal without introducing any unwanted thermal damage.

Roll-to-Roll Nanoforming of Metals Using Laser-Induced Superplasticity.

PubMed

Goswami, Debkalpa; Munera, Juan C; Pal, Aniket; Sadri, Behnam; Scarpetti, Caio Lui P G; Martinez, Ramses V

2018-05-24

This Letter describes a low-cost, scalable nanomanufacturing process that enables the continuous forming of thin metallic layers with nanoscale accuracy using roll-to-roll, laser-induced superplasticity (R2RLIS). R2RLIS uses a laser shock to induce the ultrahigh-strain-rate deformation of metallic films at room temperature into low-cost polymeric nanomolds, independently of the original grain size of the metal. This simple and inexpensive nanoforming method does not require access to cleanrooms and associated facilities, and can be easily implemented on conventional CO 2 lasers, enabling laser systems commonly used for rapid prototyping or industrial cutting and engraving to fabricate uniform and three-dimensional crystalline metallic nanostructures over large areas. Tuning the laser power during the R2RLIS process enables the control of the aspect ratio and the mechanical and optical properties of the fabricated nanostructures. This roll-to-roll technique successfully fabricates mechanically strengthened gold plasmonic nanostructures with aspect ratios as high as 5 that exhibit high oxidation resistance and strong optical field enhancements. The CO 2 laser used in R2RLIS can also integrate the fabricated nanostructures on transparent flexible substrates with robust interfacial contact. The ability to fabricate ultrasmooth metallic nanostructures using roll-to-roll manufacturing enables the large scale production, at a relatively low-cost, of flexible plasmonic devices toward emerging applications.

Fractional resurfacing in the Asian patient: Current state of the art.

PubMed

Wat, Heidi; Wu, Douglas C; Chan, Henry Hin Lee

2017-01-01

Fractionated photothermolysis (FP) has revolutionized modern laser technology. By creating selective columns of microthermal damage, fractionated devices allows for greater treatment depths to be achieved without the prolonged downtime and risk of complications seen in traditional fully ablative laser resurfacing. Fractional resurfacing is a proven method to treat a variety of cutaneous conditions. In the Caucasian patient, a wide range of devices and treatment settings can be utilized safely and effectively. However, ethnic skin requires special consideration due to its unique pigmentary characteristics and clinical presentations. In this review article, we detail the current indications and strategies to optimize results and mitigate complications when utilizing fractional resurfacing for the Asian patient. A review of the MEDLINE English literature was conducted on fractionated laser devices studied in the Asian population. Articles included describe non-ablative devices including fractionated erbium glass, thulium fiber, diode, and radiofrequency devices; and ablative devices including fractionated carbon dioxide (CO 2 ) laser, erbium yttrium aluminum garnet and yttrium scandium gallium garnet (YSGG) laser. These data were integrated with the expert opinion of the authors. Taking into account the unique characteristics and cosmetic concerns of the Asian population, fractional resurfacing can be considered a safe and effective option for the treatment of atrophic and hypertrophic scarring, and photorejuvenation in ethnic skin types. Select cases of melasma may be treated with fractionated non-ablative devices, but utilized with caution. The predominant complication associated with fractional resurfacing for these conditions is post-inflammatory hyperpigmentation (PIH) and rebound worsening of melasma. A greater number of treatments at lower density settings and wider treatment intervals typically produce the lowest risks of PIH without compromising treatment efficacy. Lasers Surg. Med. 49:45-59, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

The NASA high power carbon dioxide laser: A versatile tool for laser applications

NASA Technical Reports Server (NTRS)

Lancashire, R. B.; Alger, D. L.; Manista, E. J.; Slaby, J. G.; Dunning, J. W.; Stubbs, R. M.

1976-01-01

A closed-cycle, continuous wave, carbon dioxide high power laser has been designed and fabricated to support research for the identification and evaluation of possible high power laser applications. The device is designed to generate up to 70 kW of laser power in annular shape beams from 1 to 9 cm in diameter. Electric discharge, either self sustained or electron beam sustained, is used for excitation. This laser facility provides a versatile tool on which research can be performed to advance the state-of-the-art technology of high power CO2 lasers in such areas as electric excitation, laser chemistry, and quality of output beams. The facility provides a well defined, continuous wave beam for various application experiments, such as propulsion, power conversion, and materials processing.

Use of flexible hollow-core CO2 laser in microsurgical resection of CNS lesions: early surgical experience.

PubMed

Killory, Brendan D; Chang, Steve W; Wait, Scott D; Spetzler, Robert F

2010-06-01

The CO2 laser has a long history in both experimental and clinical neurosurgery. However, its use over the past decade has been limited by its cumbersome design and bulky set-up of the micromanipulator. These limitations are amplified when it is used with the operating microscope. These restrictions are addressed by the Omniguide fiber, which delivers the beam through flexible hollow-core photonic bandgap mirror fibers and allows the laser to be wielded like any other surgical instrument. The attending neurosurgeon prospectively assessed the usefulness of the laser in its first 45 consecutive uses at our institution based on a scale of 1 to 5. The series included 11 cavernous malformations, 14 meningiomas, 7 ependymomas, 3 metastases, 3 astrocytomas, and 7 miscellaneous lesions. The laser was set up 91 times and used in 45 cases. The Omniguide fiber failed 5 times. No adverse events involving patients or staff were associated with laser use. The mean utility score was 3.7 +/- 0.8 (range, 2-5). The laser was most helpful in debulking fibrous lesions too tough for ultrasonic aspiration and lesions adherent to delicate neurovascular structures. The laser was not helpful with highly vascular tumors. In our early experience, the Omniguide laser was very helpful in selected cases in resecting specific types of lesions without complications; we have added the device to our neurosurgical armamentarium.

A histopathologic evaluation of the Plasma Skin Regeneration System (PSR) versus a standard carbon dioxide resurfacing laser in an animal model.

PubMed

Fitzpatrick, R; Bernstein, E; Iyer, S; Brown, D; Andrews, P; Penny, K

2008-02-01

A variety of high energy, pulsed, and scanned carbon dioxide lasers are available to perform cutaneous resurfacing. Rhytec has developed a device for skin regeneration that utilizes energy delivered via a burst of nitrogen plasma. This study was undertaken to benchmark the energy outputs of the plasma skin regeneration device as compared to an ultra-short pulsed carbon dioxide laser (the control device). The two systems were compared for time to complete healing, and the healing response post-treatment. Three Yucatan mini-pigs were utilized for this study. Following anesthesia, five experimental sites were marked along the skin atop the psoas muscle on each side of the spine. Treatment was applied using either the plasma skin regeneration system or the carbon dioxide laser, with one site remaining untreated as a control. Biopsies were taken from all treatment sites 0, 2, 7, 14, 30, and 60 days following treatment and processed to hematoxylin-eosin staining. Histopathologic examination was performed by observers blinded as to the treatment conditions. Skin treated with the plasma skin regeneration device showed a wider range of tissue effects across the energy settings used as compared to the laser treatment. All treatment sites had clinically regenerated epidermis by 7 days after treatment, with active cellular response below the D/E junction noted at the day 30 time-point at energies ranging from 2 to 4 J. The Rhytec PSR system provides an attractive alternative to standard CO2 laser with good remodeling of tissue architecture. Epidermis regenerated after PSR treatment shows a smoother surface profile than adjacent untreated tissue.

Ablative skin resurfacing.

PubMed

Agrawal, Nidhi; Smith, Greg; Heffelfinger, Ryan

2014-02-01

Ablative laser resurfacing has evolved as a safe and effective treatment for skin rejuvenation. Although traditional lasers were associated with significant thermal damage and lengthy recovery, advances in laser technology have improved safety profiles and reduced social downtime. CO2 lasers remain the gold standard of treatment, and fractional ablative devices capable of achieving remarkable clinical improvement with fewer side effects and shorter recovery times have made it a more practical option for patients. Although ablative resurfacing has become safer, careful patient selection and choice of suitable laser parameters are essential to minimize complications and optimize outcomes. This article describes the current modalities used in ablative laser skin resurfacing and examines their efficacy, indications, and possible side effects. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Recycling of laser and plasma radiation energy for enhancement of extreme ultraviolet sources for nanolithography

NASA Astrophysics Data System (ADS)

Sizyuk, V.; Sizyuk, T.; Hassanein, A.; Johnson, K.

2018-01-01

We have developed comprehensive integrated models for detailed simulation of laser-produced plasma (LPP) and laser/target interaction, with potential recycling of the escaping laser and out-of-band plasma radiation. Recycling, i.e., returning the escaping laser and plasma radiation to the extreme ultraviolet (EUV) generation region using retroreflective mirrors, has the potential of increasing the EUV conversion efficiency (CE) by up to 60% according to our simulations. This would result in significantly reduced power consumption and/or increased EUV output. Based on our recently developed models, our High Energy Interaction with General Heterogeneous Target Systems (HEIGHTS) computer simulation package was upgraded for LPP devices to include various radiation recycling regimes and to estimate the potential CE enhancement. The upgraded HEIGHTS was used to study recycling of both laser and plasma-generated radiation and to predict possible gains in conversion efficiency compared to no-recycling LPP devices when using droplets of tin target. We considered three versions of the LPP system including a single CO2 laser, a single Nd:YAG laser, and a dual-pulse device combining both laser systems. The gains in generating EUV energy were predicted and compared for these systems. Overall, laser and radiation energy recycling showed the potential for significant enhancement in source efficiency of up to 60% for the dual-pulse system. Significantly higher CE gains might be possible with optimization of the pre-pulse and main pulse parameters and source size.

An overview of optical diagnostics developed for the Lockheed Martin compact fusion reactor

NASA Astrophysics Data System (ADS)

Sommers, Bradley; Raymond, Anthony; Gucker, Sarah; Lockheed Martin Compact Fusion Reactor Team

2017-10-01

The T4B experiment is a linear, encapsulated ring cusp confinement device, designed to develop a physics and technology basis for a follow-on high beta machine as part of the compact fusion reactor program. Toward this end, a collection of non-invasive optical diagnostics have been developed to investigate confinement, neutral beam heating, and source behavior on the T4B device. These diagnostics include: (1) a multipoint Thomson scattering system employing a 532 nm Nd:YAG laser and high throughput spectrometer to measure 1D profiles of electron density and temperature, (2) a dispersion interferometer utilizing a continuous-wave CO2 laser (10.6 μm) to measure time resolved, line-integrated electron density, and (3) a bolometer suite utilizing four AXUV photodiodes with 64 lines of sight to generate 2D reconstructions of total radiative power and soft x-ray emission (via beryllium filters). An overview of design methods, including laser systems, detection schemes, and data analysis techniques is presented as well as results to date.

Design of CO2 dispersion interferometer based on the ratio of modulation amplitudes on EAST

NASA Astrophysics Data System (ADS)

Li, W. M.; Liu, H. Q.; Yang, Y.; Zeng, L.; Yao, Y.; Zou, Z. Y.; Wei, X. C.; Jie, Y. X.

2018-02-01

A dispersion interferometer (DI) system is one of the more promising density measurement methods for large, high density fusion devices as they have considerable immunity to mechanical vibration and a shorter wavelength which helps to prevent fringe jump errors. In this paper, a DI system with a photoelastic modulator (PEM) has been designed for high density measurements on the EAST tokamak with vertical double pass optical layout. The bench test of all system components was done, especially for the specific nonlinear crystal for DI system. The second hamonic power with the AgGaSe2 nonlinear crystal can reach to 22.85 μW at 20 W fundamental power of CO2 laser. The second-harmonic power based on the AgGaSe2 show a good linear relationship with the various power of the CO2 laser. Based on the bench test results, the new DI system design will be realized and utilized on EAST.

The Role of the CO2 Laser and Fractional CO2 Laser in Dermatology

PubMed Central

Omi, Tokuya; Numano, Kayoko

2014-01-01

Background: Tremendous advances have been made in the medical application of the laser in the past few decades. Many diseases in the dermatological field are now indications for laser treatment that qualify for reimbursement by many national health insurance systems. Among laser types, the carbon dioxide (CO2) laser remains an important system for the dermatologist. Rationale: The lasers used in photosurgery have wavelengths that differ according to their intended use and are of various types, but the CO2 laser is one of the most widely used lasers in the dermatology field. With its wavelength in the mid-infrared at 10,600 nm, CO2 laser energy is wellabsorbed in water. As skin contains a very high water percentage, this makes the CO2 laser ideal for precise, safe ablation with good hemostasis. In addition to its efficacy in ablating benign raised lesions, the CO2 laser has been reported to be effective in the field of esthetic dermatology in the revision of acne scars as well as in photorejuvenation. With the addition of fractionation of the beam of energy into myriad microbeams, the fractional CO2 laser has offered a bridge between the frankly full ablative indications and the nonablative skin rejuvenation systems of the 2000s in the rejuvenation of photoaged skin on and off the face. Conclusions: The CO2 laser remains an efficient, precise and safe system for the dermatologist. Technological advances in CO2 laser construction have meant smaller spot sizes and greater precision for laser surgery, and more flexibility in tip sizes and protocols for fractional CO2 laser treatment. The range of dermatological applications of the CO2 laser is expected to continue to increase in the future. PMID:24771971

The Role of the CO2 Laser and Fractional CO2 Laser in Dermatology.

PubMed

Omi, Tokuya; Numano, Kayoko

2014-03-27

Tremendous advances have been made in the medical application of the laser in the past few decades. Many diseases in the dermatological field are now indications for laser treatment that qualify for reimbursement by many national health insurance systems. Among laser types, the carbon dioxide (CO2) laser remains an important system for the dermatologist. The lasers used in photosurgery have wavelengths that differ according to their intended use and are of various types, but the CO2 laser is one of the most widely used lasers in the dermatology field. With its wavelength in the mid-infrared at 10,600 nm, CO2 laser energy is wellabsorbed in water. As skin contains a very high water percentage, this makes the CO2 laser ideal for precise, safe ablation with good hemostasis. In addition to its efficacy in ablating benign raised lesions, the CO2 laser has been reported to be effective in the field of esthetic dermatology in the revision of acne scars as well as in photorejuvenation. With the addition of fractionation of the beam of energy into myriad microbeams, the fractional CO2 laser has offered a bridge between the frankly full ablative indications and the nonablative skin rejuvenation systems of the 2000s in the rejuvenation of photoaged skin on and off the face. The CO2 laser remains an efficient, precise and safe system for the dermatologist. Technological advances in CO2 laser construction have meant smaller spot sizes and greater precision for laser surgery, and more flexibility in tip sizes and protocols for fractional CO2 laser treatment. The range of dermatological applications of the CO2 laser is expected to continue to increase in the future.

Investigation of laser irradiation of WC-Co cemented carbides inside a scanning electron microscope (LASEM)

NASA Astrophysics Data System (ADS)

Schultrich, B.; Wetzig, K.

1987-09-01

A combination of SEM and laser enables direct observation of structural modifications by a high-energy input. With this new device, melting phenomena and fracture processes in a WC-6 percent Co hard metal were investigated. The first laser pulse leads to melting of a thin surface layer with the formation of blisters and craters. Cracking is induced by the relaxation of compressive surface stresses during the high-temperature stage and the appearance of tensile stresses during cooling. Besides crack formation and extension, complete welding of crack surfaces was observed after repeated laser irradiation.

Effectiveness of CO2 laser with subcision in patients with acne scars.

PubMed

Anupama, Y G; Wahab, Afthab Jameela

2016-11-01

Post-acne facial scarring has always been a challenge to treat. It requires multiple therapeutic modalities as single modality is not hundred percent effective. Therefore, we have combined CO 2 laser resurfacing with subcision in patients with acne scars for better results. The aim is to study the effectiveness and side effects of CO 2 laser with subcision in patients with atrophic acne scars. Fifty patients were selected for the study. Baseline grading was done with Goodman and Baron grading system. Twenty-five patients were randomly selected for subcision followed by CO 2 laser and the remaining patients were selected for CO 2 laser alone. The treatment was done for four sessions at 4-week interval. Clinical photographs were obtained for evaluation. CO 2 laser with subcision showed excellent response in grade-2 and -3 acne scars. Statistically there is a significant difference between CO 2 laser following subcision and CO 2 laser alone at 5% level (p < 0.05). Both procedures were well tolerated with minimal side effects. The highly versatile CO 2 laser is useful for treating acne scars. Subcision prior to the CO 2 laser procedure showed better improvement when compared to CO 2 laser alone. Thus, in acne scars, multiple therapeutic modalities achieve better results.

On the Initiation Mechanism in Exploding Bridgewire and Laser Detonators

NASA Astrophysics Data System (ADS)

Stewart, D. Scott; Thomas, K.; Saenz, J.

2005-07-01

Since its invention by Los Alamos during the Manhattan Project era the exploding bridgewire detonator (EBW) has seen tremendous use and study. Recent development of a laser-powered device with detonation properties similar to an EBW is reviving interest in the basic physics of the Deflagration-to-Detonation (DDT) process in both of these devices,[1]. Cutback experiments using both laser interferometry and streak camera observations are providing new insight into the initiation mechanism in EBWs. These measurements are being correlated to a DDT model of compaction to detonation and shock to detonation developed previously by Xu and Stewart, [2]. The DDT model is incorporated into a high-resolution, multi-material model code for simulating the complete process. Model formulation and predictions against the test data will be discussed. REFS. [1] A. Munger, J. Kennedy, A. Akinci, and K. Thomas, "Dev. of a Laser Detonator" 30th Int. Pyrotechnics Seminar, Fort Collins, CO, (2004). [2] Xu, S. and Stewart, D. S. Deflagration to detonation transition in porous energetic materials: A model study. J. Eng. Math., 31, 143-172 (1997)

CO laser angioplasty system: efficacy of manipulatable laser angioscope catheter

NASA Astrophysics Data System (ADS)

Arai, Tsunenori; Kikuchi, Makoto; Mizuno, Kyoichi; Sakurada, Masami; Miyamoto, Akira; Arakawa, Koh; Kurita, Akira; Nakamura, Haruo; Takeuchi, Kiyoshi; Utsumi, Atsushi; Akai, Yoshiro

1992-08-01

A percutaneous transluminal coronary angioplasty system using a unique combination of CO laser (5 micrometers ) and As-S infrared glass fiber under the guidance of a manipulatable laser angioscope catheter is described. The ablation and guidance functions of this system are evaluated. The angioplasty treatment procedure under angioscope guidance was studied by in vitro model experiment and in vivo animal experiment. The whole angioplasty system is newly developed. That is, a transportable compact medical CO laser device which can emit up to 10 W, a 5 F manipulatable laser angioscope catheter, a thin CO laser cable of which the diameter is 0.6 mm, an angioscope imaging system for laser ablation guidance, and a system controller were developed. Anesthetized adult mongrel dogs (n equals 5) with an artificial complete occlusion in the femoral artery and an artificial human vessel model including occluded or stenotic coronary artery were used. The manipulatability of the catheter was drastically improved (both rotation and bending), therefore, precise control of ablation to expand stenosis was obtained. A 90% artificial stenosis made of human yellow plaque in 4.0 mm diameter in the vessel was expanded to 70% stenosis by repetitive CO laser ablations of which total energy was 220 J. All procedures were performed and controlled under angioscope visualization.

Standoff laser-induced thermal emission of explosives

NASA Astrophysics Data System (ADS)

Galán-Freyle, Nataly Y.; Pacheco-Londoño, Leonardo C.; Figueroa-Navedo, Amanda; Hernandez-Rivera, Samuel P.

2013-05-01

A laser mediated methodology for remote thermal excitation of analytes followed by standoff IR detection is proposed. The goal of this study was to determine the feasibility of using laser induced thermal emission (LITE) from vibrationally excited explosives residues deposited on surfaces to detect explosives remotely. Telescope based FT-IR spectral measurements were carried out to examine substrates containing trace amounts of threat compounds used in explosive devices. The highly energetic materials (HEM) used were PETN, TATP, RDX, TNT, DNT and ammonium nitrate with concentrations from 5 to 200 μg/cm2. Target substrates of various thicknesses were remotely heated using a high power CO2 laser, and their mid-infrared (MIR) thermally stimulated emission spectra were recorded. The telescope was configured from reflective optical elements in order to minimize emission losses in the MIR frequencies and to provide optimum overall performance. Spectral replicas were acquired at a distance of 4 m with an FT-IR interferometer at 4 cm- 1 resolution and 10 scans. Laser power was varied from 4-36 W at radiation exposure times of 10, 20, 30 and 60 s. CO2 laser powers were adjusted to improve the detection and identification of the HEM samples. The advantages of increasing the thermal emission were easily observed in the results. Signal intensities were proportional to the thickness of the coated surface (a function of the surface concentration), as well as the laser power and laser exposure time. For samples of RDX and PETN, varying the power and time of induction of the laser, the calculated low limit of detections were 2 and 1 μg/cm2, respectively.

Combined fractional resurfacing (10600 nm/1540 nm): Tridimensional imaging evaluation of a new device for skin rejuvenation.

PubMed

Mezzana, Paolo; Valeriani, Maurizio; Valeriani, Roberto

2016-11-01

In this study were described the results, by tridimensional imaging evaluation, of the new "Combined Fractional Resurfacing" technique with the first fractional laser that overtakes the limits of traditional ablative, nonablative fractional resurfacing by combining CO 2 ablative and GaAs nonablative lasers. These two wavelengths can work separately or in a mixed modality to give the best treatment choice to all the patients. In this study, it is demonstrated that the simultaneous combination of the CO 2 wavelength (10600 nm) and GaAs wavelength (1540 nm) reduced the downtime, reduced pain during the treatment, and produced better results on fine wrinkles reduction and almost the same results on pigmentation as seen with 3D analysis by Antera (Miravex).

Optical Breath Gas Sensor for Extravehicular Activity Application

NASA Technical Reports Server (NTRS)

Wood, William R.; Casias, Miguel E.; Vakhtin, Andrei B.; Pilgrim, Jeffrey S.; Chullen, Cinda; Falconi, Eric A.; McMillin, Summer

2013-01-01

The function of the infrared gas transducer used during extravehicular activity in the current space suit is to measure and report the concentration of carbon dioxide (CO2) in the ventilation loop. The next generation portable life support system (PLSS) requires next generation CO2 sensing technology with performance beyond that presently in use on the Space Shuttle/International Space Station extravehicular mobility unit (EMU). Accommodation within space suits demands that optical sensors meet stringent size, weight, and power requirements. A laser diode spectrometer based on wavelength modulation spectroscopy is being developed for this purpose by Vista Photonics, Inc. Two prototype devices were delivered to NASA Johnson Space Center (JSC) in September 2011. The sensors incorporate a laser diode-based CO2 channel that also includes an incidental water vapor (humidity) measurement and a separate oxygen channel using a vertical cavity surface emitting laser. Both prototypes are controlled digitally with a field-programmable gate array/microcontroller architecture. The present development extends and upgrades the earlier hardware to the Advanced PLSS 2.0 test article being constructed and tested at JSC. Various improvements to the electronics and gas sampling are being advanced by this project. The combination of low power electronics with the performance of a long wavelength laser spectrometer enables multi-gas sensors with significantly increased performance over that presently offered in the EMU.

The carbon dioxide laser surgical unit as an instrument for surgery of brain tumours--its advantages and disadvantages.

PubMed

Takizawa, T

1984-01-01

The author started in 1969 his studies on developing the practical models of the carbon dioxide laser surgical units and produced Medilaser-S, Model MEL-42 and MEL-444. By the end of 1982 the author had operated on 143 cases of brain tumour with the laser. Most of those cases were brain tumours which were difficult or impossible to remove by conventional means. The major points of this paper are as follows: The principle of the laser, the mechanism of the CO2 laser, the biomedical features of the CO2 laser, the advantages and disadvantages of the CO2 laser, indications and contraindications for the use of the CO2 laser, development of the CO2 laser surgical units, surgical procedures and techniques of brain tumour laser surgery, adjuvant methods of laser surgery and comparison between the CO2 laser and the Nd-YAG laser.

Q-switched all-solid-state lasers and application in processing of thin-film solar cell

NASA Astrophysics Data System (ADS)

Liu, Liangqing; Wang, Feng

2009-08-01

Societal pressure to renewable clean energy is increasing which is expected to be used as part of an overall strategy to address global warming and oil crisis. Photovoltaic energy conversion devices are on a rapidly accelerating growth path driven by government, of which the costs and prices lower continuously. The next generation thin-film devices are considered to be more efficiency and greatly reduced silicon consumption, resulting in dramatically lower per unit fabrication costs. A key aspect of these devices is patterning large panels to create a monolithic array of series-interconnected cells to form a low current, high voltage module. This patterning is accomplished in three critical scribing processes called P1, P2, and P3. All-solid-state Q-switched lasers are the technology of choice for these processes, due to their advantages of compact configuration, high peak-value power, high repeat rate, excellent beam quality and stability, delivering the desired combination of high throughput and narrow, clean scribes. The end pumped all-solid-state lasers could achieve 1064nm IR resources with pulse width of nanoseconds adopting acoustic-optics Q-switch, shorter than 20ns. The repeat rate is up to 100kHz and the beam quality is close to diffraction limit. Based on this, 532nm green lasers, 355nm UV lasers and 266nm DUV lasers could be carried out through nonlinear frequency conversion. Different wave length lasers are chose to process selective materials. For example, 8-15 W IR lasers are used to scribe the TCO film (P1); 1-5 W green lasers are suitable for scribing the active semiconductor layers (P2) and the back contact layers (P3). Our company, Wuhan Lingyun Photo-electronic System Co. Ltd, has developed 20W IR and 5W green end-pumped Q-switched all-solid-state lasers for thin-film solar industry. Operating in high repeat rates, the speed of processing is up to 2.0 m/s.

CO2 laser modeling

NASA Technical Reports Server (NTRS)

Johnson, Barry

1992-01-01

The topics covered include the following: (1) CO2 laser kinetics modeling; (2) gas lifetimes in pulsed CO2 lasers; (3) frequency chirp and laser pulse spectral analysis; (4) LAWS A' Design Study; and (5) discharge circuit components for LAWS. The appendices include LAWS Memos, computer modeling of pulsed CO2 lasers for lidar applications, discharge circuit considerations for pulsed CO2 lidars, and presentation made at the Code RC Review.

Laser absorption phenomena in flowing gas devices

NASA Technical Reports Server (NTRS)

Chapman, P. K.; Otis, J. H.

1976-01-01

A theoretical and experimental investigation is presented of inverse Bremsstrahlung absorption of CW CO2 laser radiation in flowing gases seeded with alkali metals. In order to motivate this development, some simple models are described of several space missions which could use laser powered rocket vehicles. Design considerations are given for a test call to be used with a welding laser, using a diamond window for admission of laser radiation at power levels in excess of 10 kW. A detailed analysis of absorption conditions in the test cell is included. The experimental apparatus and test setup are described and the results of experiments presented. Injection of alkali seedant and steady state absorption of the laser radiation were successfully demonstrated, but problems with the durability of the diamond windows at higher powers prevented operation of the test cell as an effective laser powered thruster.

The application of robotics to microlaryngeal laser surgery.

PubMed

Buckmire, Robert A; Wong, Yu-Tung; Deal, Allison M

2015-06-01

To evaluate the performance of human subjects, using a prototype robotic micromanipulator controller in a simulated, microlaryngeal operative setting. Observational cross-sectional study. Twenty-two human subjects with varying degrees of laser experience performed CO2 laser surgical tasks within a simulated microlaryngeal operative setting using an industry standard manual micromanipulator (MMM) and a prototype robotic micromanipulator controller (RMC). Accuracy, repeatability, and ablation consistency measures were obtained for each human subject across both conditions and for the preprogrammed RMC device. Using the standard MMM, surgeons with >10 previous laser cases performed superior to subjects with fewer cases on measures of error percentage and cumulative error (P = .045 and .03, respectively). No significant differences in performance were observed between subjects using the RMC device. In the programmed (P/A) mode, the RMC performed equivalently or superiorly to experienced human subjects on accuracy and repeatability measures, and nearly an order of magnitude better on measures of ablation consistency. The programmed RMC performed significantly better for repetition error when compared to human subjects with <100 previous laser cases (P = .04). Experienced laser surgeons perform better than novice surgeons on tasks of accuracy and repeatability using the MMM device but roughly equivalently using the novel RMC. Operated in the P/A mode, the RMC performs equivalently or superior to experienced laser surgeons using the industry standard MMM for all measured parameters, and delivers an ablation consistency nearly an order of magnitude better than human laser operators. NA. © 2014 The American Laryngological, Rhinological and Otological Society, Inc.

Histological evaluation of vertical laser channels from ablative fractional resurfacing: an ex vivo pig skin model.

PubMed

Skovbølling Haak, Christina; Illes, Monica; Paasch, Uwe; Hædersdal, Merete

2011-07-01

Ablative fractional resurfacing (AFR) represents a new treatment potential for various skin conditions and new laser devices are being introduced. It is important to gain information about the impact of laser settings on the dimensions of the created laser channels for obtaining a safe and efficient treatment outcome. The aim of this study was to establish a standard model to document the histological tissue damage profiles after AFR and to test a new laser device at diverse settings. Ex vivo abdominal pig skin was treated with a MedArt 620, prototype fractional carbon dioxide (CO(2)) laser (Medart, Hvidovre, Denmark) delivering single microbeams (MB) with a spot size of 165 μm. By using a constant pulse duration of 2 ms, intensities of 1-18 W, single and 2-4 stacked pulses, energies were delivered in a range from 2-144 mJ/MB. Histological evaluations included 3-4 high-quality histological measurements for each laser setting (n = 28). AFR created cone-shaped laser channels. Ablation depths varied from reaching the superficial dermis (2 mJ, median 41 μm) to approaching the subcutaneous fat (144 mJ, median 1,943 μm) and correlated to the applied energy levels in an approximate linear relation (r(2) = 0.84, p < 0.001). The dermal ablation width increased slightly within the energy range of 4-144 mJ (median 163 μm). The thickness of the coagulation zone reached a plateau around 65 μm at energies levels above 16 mJ. The calculated volumes of ablated tissue increased with increasing energies. We suggest this ex vivo pig skin model to characterize AFR laser channels histologically.

Ultrafast Manipulation of Magnetic Order with Electrical Pulses

NASA Astrophysics Data System (ADS)

Yang, Yang

During the last 30 years spintronics has been a very rapidly expanding field leading to lots of new interesting physics and applications. As with most technology-oriented fields, spintronics strives to control devices with very low energy consumption and high speed. The combination of spin and electronics inherent to spintronics directly tackles energy efficiency, due to the non-volatility of magnetism. However, speed of operation of spintronic devices is still rather limited ( nanoseconds), due to slow magnetization precessional frequencies. Ultrafast magnetism (or opto-magnetism) is a relatively new field that has been very active in the last 20 years. The main idea is that intense femtosecond laser pulses can be used in order to manipulate the magnetization at very fast time-scales ( 100 femtoseconds). However, the use of femtosecond lasers poses great application challenges such as diffraction limited optical spot sizes which hinders device density, and bulky and expensive integration of femtosecond lasers into devices. In this thesis, our efforts to combine ultrafast magnetism and spintronics are presented. First, we show that the magnetization of ferrimagnetic GdFeCo films can be switched by picosecond electronic heat current pulses. This result shows that a non-thermal distribution of electrons directly excited by laser is not necessary for inducing ultrafast magnetic dynamics. Then, we fabricate photoconductive switch devices on a LT-GaAs substrate, to generate picosecond electrical pulses. Intense electrical pulses with 10ps (FWHM) duration and peak current up to 3A can be generated and delivered into magnetic films. Distinct magnetic dynamics in CoPt films are found between direct optical heating and electrical heating. More importantly, by delivering picosecond electrical pulses into GdFeCo films, we are able to deterministically reverse the magnetization of GdFeCo within 10ps. This is more than one order of magnitude faster than any other electrically controlled magnetic switching. Our results present a fundamentally new switching mechanism electrically, without requirement for any spin polarized current or spin transfer/orbit torques. Our discovery that ultrafast magnetization switching can be achieved with electrical pulses will launch a new frontier of spintronics science and herald a new generation of spintronic devices that operate at high speed with low energy consumption. At last, to push ultrafast spintronics to practical use, ultrafast switching of a ferromagnetic film is desired. By exploiting the exchange interaction between GdFeCo and ferromagnetic Co/Pt layer, we achieved ultrafast (sub 10ps) switching of ferromagnetic film with a single laser pulse. This result will open up the possibility to control ferromagnetic materials at ultrafast time scale, critical for practical applications.

Selective removal of demineralized enamel using a CO2 laser coupled with near-IR reflectance imaging

NASA Astrophysics Data System (ADS)

Tom, Henry; Chan, Kenneth H.; Saltiel, Daniel; Fried, Daniel

2015-02-01

Detection and diagnosis of early dental caries lesions can be difficult due to variable tooth coloration, staining of the teeth and poor contrast between sound and demineralized enamel. These problems can be overcome by using near-infrared (NIR) imaging. Previous studies have demonstrated that lasers can be integrated with NIR imaging devices, allowing image-guided ablation. The aim of this study was to demonstrate that NIR light at 1500 - 1700 nm can be used to guide a 9.3-μm CO2 laser for the selective ablation of early demineralization on tooth occlusal surfaces. The occlusal surfaces of ten sound human molars were used in this in-vitro study. Shallow simulated caries lesions of varying depth and position were produced on tooth occlusal surfaces using a demineralization solution. Sequential NIR reflectance images at 1500 - 1700 nm were used to guide the laser for selective ablation of the lesion areas. Digital microscopy and polarization sensitive optical coherence tomography (PS-OCT) were used to assess the selectivity of removal. This study demonstrates that high contrast NIR reflectance images can be used for the image-guided laser ablation of early demineralization from tooth occlusal surfaces.

High speed pulsed laser cutting of LiCoO2 Li-ion battery electrodes

NASA Astrophysics Data System (ADS)

Lutey, Adrian H. A.; Fortunato, Alessandro; Carmignato, Simone; Fiorini, Maurizio

2017-09-01

Laser cutting of Li-ion battery electrodes represents an alternative to mechanical blanking that avoids complications associated with tool wear and allows assembly of different cell geometries with a single device. In this study, laser cutting of LiCoO2 Li-ion battery electrodes is performed at up to 5m /s with a 1064nm wavelength nanosecond pulsed fiber laser with a maximum average power of 500W and a repetition rate of up to 2MHz . Minimum average cutting power for cathode and anode multi-layer films is established for 12 parameter groups with velocities over the range 1 - 5m /s , varying laser pulse fluence and overlap. Within the tested parameter range, minimum energy per unit cut length is found to decrease with increasing repetition rate and velocity. SEM analysis of the resulting cut edges reveals visible clearance widths in the range 20 - 50 μm , with cut quality found to improve with velocity due to a reduction in lateral heat conduction losses. Raman line map spectra reveal changes in the cathode at 60 μm from the cut edge, where bands at 486cm-1 and 595cm-1 , corresponding to the Eg and A1g modes of LiCoO2 , are replaced with a single wide band centered at 544cm-1 , and evidence of carbon black is no longer present. No changes in Raman spectra are observed in the anode. The obtained results suggest that further improvements in cutting efficiency and quality could be achieved by increasing the repetition rate above 2MHz , thereby improving ablation efficiency of the metallic conductor layers. The laser source utilized in the present study nonetheless represents an immediately available solution for repeatability and throughput that are superior to mechanical blanking.

Numerical solution of Boltzmann tranport equation for TEA CO 2 laser having nitrogen-lean gas mixtures to predict laser characteristics and gas lifetime

NASA Astrophysics Data System (ADS)

Kumar, Manoj; Khare, Jai; Nath, A. K.

2007-02-01

Selective laser isotope separation by TEA CO 2 laser often needs short tail-free pulses. Using laser mixtures having very little nitrogen almost tail free laser pulses can be generated. The laser pulse characteristics and its gas lifetime is an important issue for long-term laser operation. Boltzmann transport equation is therefore solved numerically for TEA CO 2 laser gas mixtures having very little nitrogen to predict electron energy distribution function (EEDF). The distribution function is used to calculate various excitation and dissociation rate of CO 2 to predict laser pulse characteristics and laser gas lifetime, respectively. Laser rate equations have been solved with the calculated excitation rates for numerically evaluated discharge current and voltage profiles to calculate laser pulse shape. The calculated laser pulse shape and duration are in good agreement with the measured laser characteristics. The gas lifetime is estimated by integrating the equation governing the dissociation of CO 2. An experimental study of gas lifetime was carried out using quadrapole mass analyzer for such mixtures to estimate the O 2 being produced due to dissociation of CO 2 in the pulse discharge. The theoretically calculated O 2 concentration in the laser gas mixture matches with experimentally observed value. In the present TEA CO 2 laser system, for stable discharge the O 2 concentration should be below 0.2%.

High-power industrial pulsed CO2 laser

NASA Astrophysics Data System (ADS)

Levin, G. I.

1983-12-01

The use of a pulsed TEA CO2 laser (with maximum average power 1.0 kW; maximum pulse energy 3.5 J; repetition frequency 400-600 Hz; half-width pulse duration 15 microsec; circular-coupling-aperture beam diameter 6, 8, or 12 mm; and beam divergence 10 mrad) in industrial welding applications is investigated experimentally in carbon and stainless steels, Zr, Ti, and Ni of various thicknesses. The power required to melt the metals is found to be about 120-200 W/sq cm, or 5-6 times less than that for CW lasers. It is shown that deep narrow-seam welds with mechanical properties identical to those of the bulk metal can be obtained with little or no intercrystalline corrosion or thermal distortion of the surrounding area. Disadvantages such as the 65-dB noise level, low welding speed, formation of an overlap at the top and a crater at the bottom of the weld, and root porosity are considered the primary limitations on the applicability of the device tested.

A systematic review of comparative studies of CO2 and erbium:YAG lasers in resurfacing facial rhytides (wrinkles).

PubMed

Chen, Kee-Hsin; Tam, Ka-Wai; Chen, I-Fan; Huang, Shihping Kevin; Tzeng, Pei-Chuan; Wang, Hsian-Jenn; Chen, Chiehfeng Cliff

2017-08-01

Laser resurfacing is used to minimize wrinkles, solar scars and sequelae of acne. Purpose of the systematic review was to compare resurfacing outcomes of CO 2 laser and erbium: yttrium aluminium garnet (erb:YAG) laser therapies. Medline, Cochrane Library, EMBASE and Google Scholar databases were searched until 9 April 2015 using the following terms: laser, carbon dioxide/CO 2 , facial wrinkles, rhytides and erbium-doped yttrium aluminium garnet/erbium:YAG/Er:YAG. Two-armed controlled split faced studies that compared CO 2 laser and erbium:YAG laser in patients with mild-to-moderate facial wrinkles or rhytides were included. The pooled data in this study and findings of other studies support the greater efficacy with the CO 2 laser in improving facial wrinkles, but the erb:YAG laser was associated with a better complication profile compared with the CO 2 laser. Except one case of hypopigmentation, other complications (i.e., erythema, hyperpigmentation and crusting) and their rates were reported by studies examining both lasers. In general, the CO 2 laser appeared to be more efficacious then the erb:YAG laser in treating facial wrinkles. Both lasers treatments were well tolerated.

The design and development of CO2 medium-level laser power calibration system for industrial and medical applications in Thailand

NASA Astrophysics Data System (ADS)

Nontapot, Kanokwan

2018-03-01

The carbon dioxide laser (CO2 laser) is one of the most useful and is the highest CW laser at the present. The laser produces infrared light at 10.6 um. Due to its high power, CO2 lasers are usually used in industrial applications such as cutting and welding, or for engraving at less power. CO2 lasers are also used widely in medical applications, such as laser surgery, skin resurfacing, and removing mold, due to water (biological tissue) absorb light at this wavelength very well. CO2 lasers are also used as LIDAR laser source for military range finding applications because of the transparency of the atmosphere to infrared light. Due to the increasing use of CO2 lasers laser in industrial and medical applications in Thailand, the National Institute of Metrology (Thailand) has set up a CO2 laser power calibration system and provide calibration service to customers this year. The service support calibration of medium-level laser power at wavelength of 10.6 um and at power range 100 mW-10W. The design and development of the calibration system will be presented.

'Design of CO-O2 recombination catalysts for closed-cycle CO2 lasers'

NASA Technical Reports Server (NTRS)

Guinn, K.; Goldblum, S.; Noskowski, E.; Herz, R.

1989-01-01

Pulsed CO2 lasers have many applications in aeronautics, space research, weather monitoring and other areas. Full exploitation of the potential of these lasers is hampered by the dissociation of CO2 that occurs during laser operation. The development of closed-cycle CO2 lasers requires active CO-O2 recombination (CO oxidation) catalysts and design methods for implementation of catalysts inside lasers. This paper will discuss the performance criteria and constraints involved in the design of monolith catalyst configurations for use in a closed-cycle laser and will present a design study performed with a computerized design program that had been written. Trade-offs between catalyst activity and dimensions, flow channel dimensions, pressure drop, O2 conversion and other variables will be discussed.

Status of thermoelectronic laser energy conversion, TELEC

NASA Technical Reports Server (NTRS)

Britt, E. J.

1982-01-01

A concept known as a thermo-electronic laser energy converter (TELEC), was studied as a method of converting a 10.6 micron CO2 laser beam into electric power. The calculated characteristics of a TELEC seem to be well matched to the requirements of a spacecraft laser energy conversion system. The TELEC is a high power density plasma device which absorbs an intense laser beam by inverse bremsstrahlung with the plasma electrons. In the TELEC process, electromagnetic radiation is absorbed directly in the plasma electrons producing a high electron temperature. The energetic electrons diffuse out of the plasma striking two electrodes which are in contact with the plasma at the boundaries. These two electrodes have different areas: the larger one is designated as the collector, the smaller one is designated as the emitter. The smaller electrode functions as an electron emitter provide continuity of the current. Waste heat is rejected from the collector electrode. An experiment was carried out with a high power laser using a cesium vapor TELEC cell with 30 cm active length. Laser supported plasma were produced in the TELEC device during a number of laser runs over a period of several days. Electric power from the TELEC was observed with currents in the range of several amperes and output potentials of less than 1 volt.

Optical Breath Gas Sensor for Extravehicular Activity Application

NASA Technical Reports Server (NTRS)

Wood, William R.; Casias, Miguel E.; Vakhtin, Andrei B.; Pilgrim, Jeffrey S> ; Chullen, Cinda; Falconi, Eric A.

2012-01-01

The function of the infrared gas transducer used during extravehicular activity (EVA) in the current space suit is to measure and report the concentration of carbon dioxide (CO2) in the ventilation loop. The next generation Portable Life Support System (PLSS) requires next generation CO2 sensing technology with performance beyond that presently in use on the Shuttle/International Space Station extravehicular mobility unit (EMU). Accommodation within space suits demands that optical sensors meet stringent size, weight, and power requirements. A laser diode (LD) spectrometer based on wavelength modulation spectroscopy (WMS) is being developed for this purpose by Vista Photonics, Inc. Two prototype devices were delivered to NASA Johnson Space Center (JSC) in September 2011. The sensors incorporate a laser diode based CO2 channel that also includes an incidental water vapor (humidity) measurement and a separate oxygen (O2) channel using a vertical cavity surface emitting laser (VCSEL). Both prototypes are controlled digitally with a field-programmable gate array (FPGA)/microcontroller architecture. Based on the results of the initial instrument development, further prototype development and testing of instruments leveraging the lessons learned were desired. The present development extends and upgrades the earlier hardware to the Advanced PLSS 2.0 test article being constructed and tested at JSC. Various improvements to the electronics and gas sampling are being advanced by this project. The combination of low power electronics with the performance of a long wavelength laser spectrometer enables multi-gas sensors with significantly increased performance over that presently offered in the EMU. .

Safe and effective one-session fractional skin resurfacing using a carbon dioxide laser device in super-pulse mode: a clinical and histologic study.

PubMed

Trelles, Mario A; Shohat, Michael; Urdiales, Fernando

2011-02-01

Carbon dioxide (CO(2)) laser ablative fractional resurfacing produces skin damage, with removal of the epidermis and variable portions of the dermis as well as associated residual heating, resulting in new collagen formation and skin tightening. The nonresurfaced epidermis helps tissue to heal rapidly, with short-term postoperative erythema. The results for 40 patients (8 men and 32 women) after a single session of a fractional CO(2) resurfacing mode were studied. The treatments included resurfacing of the full face, periocular upper lip, and residual acne scars. The patients had skin prototypes 2 to 4 and wrinkle degrees 1 to 3. The histologic effects, efficacy, and treatment safety in various clinical conditions and for different phototypes are discussed. The CO(2) laser for fractional treatment is used in super-pulse mode. The beam is split by a lens into several microbeams, and super-pulse repetition is limited by the pulse width. The laser needs a power adaptation to meet the set fluence per microbeam. Laser pulsing can operate repeatedly on the same spot or be moved randomly over the skin, using several passes to achieve a desired residual thermal effect. Low, medium, and high settings are preprogrammed in the device, and they indicate the strength of resurfacing. A single treatment was given with the patient under topical anesthesia. However, the anesthesia was injected on areas of scar tissue. Medium settings (2 Hz, 30 W, 60 mJ) were used, and two passes were made for dark skins and degree 1 wrinkles. High settings (2 Hz, 60 W, 120 mJ) were used, and three passes were made for degree 3 wrinkles and scar tissue. Postoperatively, resurfaced areas were treated with an ointment of gentamycin, Retinol Palmitate, and DL-methionine (Novartis; Farmaceutics, S.A., Barcelona, Spain). Once epithelialization was achieved, antipigment and sun protection agents were recommended. Evaluations were performed 15 days and 2 months after treatment by both patients and clinicians. Treatment improved wrinkle aspect and scar condition, and no patient reported adverse effects or complications, irrespective of skin type, except for plaques of erythema in areas that received extra laser passes, which were not seen at the 2-month assessment. The results evaluated by clinicians were very much in correlation with those of patients. Immediately after treatment, vaporization was produced by stacked pulses, with clear ablation and collateral heat coagulation. An increased number of random pulses removed more epidermis, and with denser pulses per area, a thermal deposit was noted histologically. At 2 months, a thicker, multicelluar epidermis and an evident increase in collagen were observed. Fractional CO(2) laser permits a variety of resurfacing settings that obtain safe, effective skin rejuvenation and correct scar tissue in a single treatment.

Three-electrode low pressure discharge apparatus and method for uniform ionization of gaseous media. [CO/sub 2/ laser oscillator and pulse smoother

DOEpatents

McLellan, E.J.

1980-10-17

Uniform, transverse electrical discharges are produced in gaseous media without the necessity of switching the main discharge voltage with an external device which carries the entire discharge current. A three-electrode low pressure discharge tube is charged across its anode and cathode to below breakdown voltage using a dc voltage source. An array of resistors or capacitors can be made to discharge to the wire screen anode by means of a low energy high voltage pulse circuit producing sufficient preionization in the region between the anode and cathode to initiate and control the main discharge. The invention has been demonstrated to be useful as a CO/sub 2/ laser oscillator and pulse-smoother. It can be reliably operated in the sealed-off mode.

Prevention of CO2 laser-induced endotracheal tube fires with the laser-guard protective coating.

PubMed

Sosis, M B; Dillon, F

1992-01-01

To determine how well Laser-Guard protects polyvinyl chloride (PVC) endotracheal tubes from the carbon dioxide (CO2) laser. Bare and Laser-Guard-protected PVC endotracheal tubes were tested with 5 L/min of oxygen (O2) passing through them. Research laboratory of a university-affiliated metropolitan medical center. After moistening the Laser-Guard-protected endotracheal tubes, we subjected the tubes to CO2 laser radiation at 10 and 70 watts until combustion occurred or 60 seconds had elapsed. The bare PVC tube ignited and a "blowtorch" fire occurred after 3 seconds of CO2 laser use at 70 watts. The moistened Laser-Guard-protected PVC endotracheal tubes were not significantly damaged by 1 minute of laser use at 70 watts. Laser-Guard protects the shafts of combustible PVC endotracheal tubes from direct, high-power, continuous CO2 laser radiation.

A computer program for the design of optimum catalytic monoliths for CO2 lasers

NASA Technical Reports Server (NTRS)

Guinn, K.; Goldblum, S.; Noskowski, E.; Herz, R.

1990-01-01

Pulsed CO2 lasers have many applications in aeronautics, space research, weather monitoring and other areas. Full exploitation of the potential of these lasers is hampered by the dissociation of CO2 that occurs during laser operation. The development of closed-cycle CO2 lasers requires active CO-O2 recombination (CO oxidation) catalysts and design methods for implementation of catalysts inside lasers. The performance criteria and constraints involved in the design of catalyst configurations for use in a closed-cycle laser are discussed, and several design studies performed with a computerized design program that was written are presented. Trade-offs between catalyst activity and dimensions, flow channel dimensions, pressure drop, O2 conversion and other variables are discussed.

Temperature and pressure dependence of dichloro-difluoromethane (CF2C12) absorption coefficients for CO2 waveguide laser radiation

NASA Technical Reports Server (NTRS)

Harward, C. N.

1977-01-01

Measurements were performed to determine the pressure and temperature dependence of CFM-12 absorption coefficients for CO2 waveguide laser radiation. The absorption coefficients of CFM-12 for CO2 waveguide laser radiation were found to have no spectral structure within small spectral bandwidths around the CO2 waveguide laser lines in the CO2 spectral band for pressures above 20 torr. All of the absorption coefficients for the CO2 laser lines studied are independent of pressure above 100 torr, except for the P(36) laser CO2 spectral band. The absorption coefficients associated with the P(42) line in the same band showed the greatest change with temperature, and it also has the largest value of all the lines studied.

Parameters in fractional laser assisted delivery of topical anesthetics: Role of laser type and laser settings.

PubMed

Meesters, Arne A; Nieboer, Marilin J; Kezic, Sanja; de Rie, Menno A; Wolkerstorfer, Albert

2018-05-07

Efficacy of topical anesthetics can be enhanced by pretreatment of the skin with ablative fractional lasers. However, little is known about the role of parameters such as laser modality and laser density settings in this technique. Aims of this study were to compare the efficacy of pretreatment with two different ablative fractional laser modalities, a CO 2 laser and an Er:YAG laser, and to assess the role of laser density in ablative fractional laser assisted topical anesthesia. In each of 15 healthy subjects, four 10 × 10 mm test regions on the back were randomized to pretreatment (70-75 μm ablation depth) with CO 2 laser at 5% density, CO 2 laser at 15% density, Er:YAG laser at 5% density or Er:YAG laser at 15% density. Articaine hydrochloride 40 mg/ml + epinephrine 10 μg/ml solution was applied under occlusion to all four test regions. After 15 minutes, a pass with the CO 2 laser (1,500 μm ablation depth) was administered as pain stimulus to each test region. A reference pain stimulus was given on unanesthetized skin. The main outcome parameter, pain, was scored on a 0-10 visual analogue scale (VAS) after each pain stimulus. Median VAS scores were 1.50 [CO 2 5%], 0.50 [CO 2 15%], 1.50 [Er:YAG 5%], 0.43 [Er:YAG 15%], and 4.50 [unanesthetized reference]. VAS scores for all pretreated test regions were significantly lower compared to the untreated reference region (P < 0.01). We found no significant difference in VAS scores between the CO 2 and the Er:YAG laser pretreated regions. However, VAS scores were significantly lower at 15% density compared to 5% density for both for the CO 2 laser (P < 0.05) and the Er:YAG laser (P < 0.01). Pretreatment with the CO 2 laser was considered slightly more painful than pretreatment with Er:YAG laser by the subjects. Fractional laser assisted topical anesthesia is effective even with very low energy settings and an occlusion time of only 15 minutes. Both the CO 2 laser and the Er:YAG laser can be used to assist topical anesthesia although the CO 2 laser pretreatment is experienced as more painful. In our study settings, using articaine/epinephrine solution and an occlusion time of 15 minutes, a density of 15% was more effective than 5%. Lasers Surg. Med. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

Electronic transport and photovoltaic properties in Bi2Sr2Co2Oyepitaxial heterostructures

NASA Astrophysics Data System (ADS)

Guo, Hai-Zhong; Gu, Lin; Yang, Zhen-Zhong; Wang, Shu-Fang; Fu, Guang-Sheng; Wang, Le; Jin, Kui-Juan; Lu, Hui-Bin; Wang, Can; Ge, Chen; He, Meng; Yang, Guo-Zhen

2013-08-01

Epitaxial heterostructures constructed from the thermoelectric cobalt Bi2Sr2Co2Oy thin films and SrTiO3 as well as SrTi0.993Nb0.007O3 substrates were fabricated by pulsed-laser deposition. The scanning transmission electron microscopy results confirm that the heterostructures are epitaxial, with sharp and coherent interfaces. The temperature-dependent electrical transport properties and the Hall effects were systematically investigated. The Bi2Sr2Co2Oy/SrTi0.993Nb0.007O3 p-n heterostructure exhibits good rectifying current-voltage characteristics over a wide temperature range. A strong photovoltaic effect was observed in the Bi2Sr2Co2Oy/SrTi0.993Nb0.007O3 heterostructure, with the temperature-dependent photovoltage being systematically investigated. The present work shows a great potential of this new heterostructures as photoelectric devices.

Isotope Exchange in Oxide Catalyst

NASA Technical Reports Server (NTRS)

Hess, Robert V.; Miller, Irvin M.; Schryer, David R.; Sidney, Barry D.; Wood, George M., Jr.; Hoyt, Ronald F.; Upchurch, Billy T.; Brown, Kenneth G.

1987-01-01

Replacement technique maintains level of CO2/18 in closed-cycle CO2 lasers. High-energy, pulsed CO2 lasers using rare chemical isotopes must be operated in closed cycles to conserve gas. Rare isotopes operated in closed cycles to conserve gas. Rare isotopes as CO2/18 used for improved transmission of laser beam in atmosphere. To maintain laser power, CO2 must be regenerated, and O2 concentration kept below few tenths of percent. Conditions achieved by recombining CO and O2.

Method and apparatus for fast laser pulse detection using gaseous plasmas

DOEpatents

McLellan, Edward J.; Webb, John A.

1984-01-01

The method and device of the instant invention is a detector of pulsed laser radiation which utilizes the electromotive force generated by the plasma formed when such radiation is focused onto a surface (1). Measurements are made with a 10.6 .mu.m CO.sub.2 laser capable of producing peak intensities of 10.sup.13 W/cm.sup.2 when directed through a converging lens (2). Evacuated detector response to such laser intensity is 1 kV signal peak amplitude and subnanosecond risetimes into a 50.OMEGA. load (3). Detector performance is found to be greatly altered with the introduction of a background gas (4). For example, with one atmosphere of air, the detector produces prompt signals of the order of 1 V with subnanosecond response for pulse trains lasting 100 ns. With argon, krypton, or zenon at pressures of the order of 10 torr, the detector generates "trigger pulses" of about 250 V amplitude and 0.2 ns risetimes. Such detectors are quite robust when irradiated with high intensity laser radiation and are useful for qualitative laser beam monitoring.

LASER BIOLOGY AND MEDICINE: Medical instruments based on high-power diode and fibre lasers

NASA Astrophysics Data System (ADS)

Gapontsev, V. P.; Minaev, V. P.; Savin, V. I.; Samartsev, I. E.

2002-11-01

The characteristics and possible applications of scalpels based on diode and fibre lasers emitting at 0.97, 1.06, 1.56, and 1.9 μm, which are produced and developed by the IRE-Polyus Co., are presented. The advantages of such devices and the possibilities for increasing their output power and extending their spectral range are shown.

Laser induced disruption of bacterial spores on a microchip.

PubMed

Hofmann, Oliver; Murray, Kirk; Wilkinson, Alan-Shaun; Cox, Timothy; Manz, Andreas

2005-04-01

We report on the development of a laser based spore disruption method. Bacillus globigii spores were mixed with a laser light absorbing matrix and co-crystallized into 200-microm-wide and 20-microm-deep nanovials formed in a polydimethylsiloxane (PDMS) target plate. Surface tension effects were exploited to effect up to 125-fold spore enrichment. When the target zones were illuminated at atmospheric pressure with pulsed UV-laser light at fluences below 20 mJ cm(-2) a change in spore morphology was observed within seconds. Post illumination PCR analysis suggests the release of endogenous DNA indicative of spore disruption. For laser fluences above 20 mJ cm(-2), desorption of spores and fragments was also observed even without a matrix being employed. Desorbed material was collected in a PDMS flowcell attached to the target plate during laser illumination. This opens up a route towards the direct extraction of released DNA in an integrated spore disruption-PCR amplification microchip device.

CO2 laser drives extreme ultraviolet nano-lithography — second life of mature laser technology

NASA Astrophysics Data System (ADS)

Nowak, K. M.; Ohta, T.; Suganuma, T.; Fujimoto, J.; Mizoguchi, H.; Sumitani, A.; Endo, A.

2013-12-01

It was shown both theoretically and experimentally that nanosecond order laser pulses at 10.6 micron wavelength were superior for driving the Sn plasma extreme ultraviolet (EUV) source for nano-lithography for the reasons of higher conversion efficiency, lower production of debris and higher average power levels obtainable in CO2 media without serious problems of beam distortions and nonlinear effects occurring in competing solid-state lasers at high intensities. The renewed interest in such pulse format, wavelength, repetition rates in excess of 50 kHz and average power levels in excess of 18 kiloWatt has sparked new opportunities for a matured multi-kiloWatt CO2 laser technology. The power demand of EUV source could be only satisfied by a Master-Oscillator-Power-Amplifier system configuration, leading to a development of a new type of hybrid pulsed CO2 laser employing a whole spectrum of CO2 technology, such as fast flow systems and diffusion-cooled planar waveguide lasers, and relatively recent quantum cascade lasers. In this paper we review briefly the history of relevant pulsed CO2 laser technology and the requirements for multi-kiloWatt CO2 laser, intended for the laser-produced plasma EUV source, and present our recent advances, such as novel solid-state seeded master oscillator and efficient multi-pass amplifiers built on planar waveguide CO2 lasers.

Fractional CO2 laser is an effective therapeutic modality for xanthelasma palpebrarum: a randomized clinical trial.

PubMed

Esmat, Samia M; Elramly, Amany Z; Abdel Halim, Dalia M; Gawdat, Heba I; Taha, Hanaa I

2014-12-01

Xanthelasma palpebrarum (XP) is a common cosmetic concern. Although there is a wide range of therapeutic modalities for XP, there is no general consensus on the optimal treatment for such condition. Compare the efficacy and safety of super pulsed (SP) and fractional CO2 lasers in the treatment of XP. This prospective randomized comparative clinical study included 20 adult patients with bilateral and symmetrical XP lesions. Xanthelasma palpebrarum lesions were randomly assigned to treatment by either single session of ablative SP CO2 laser or 3 to 5 sessions of ablative fractional CO2 laser with monthly intervals. All patients were assessed using digital photography and optical coherence tomography images. Xanthelasma palpebrarum lesions on both sides were successfully removed with significant improvement in size, color, and thickness. Although lesions treated by SP CO2 laser showed significantly better improvement regarding color and thickness of the lesions, downtime and patient satisfaction were significantly better for lesions treated with fractional CO2 laser. Scarring and recurrence were significantly higher in lesions treated by SP CO2 laser. Ablative fractional CO2 laser is an effective and safe therapeutic option for XP with significantly shorter downtime and higher patient satisfaction compared with SP CO2 laser.

Flash scanning the CO2 laser: a revival of the CO2 laser in plastic surgery

NASA Astrophysics Data System (ADS)

Lach, Elliot

1994-09-01

The CO2 laser has broad clinical application yet also presents a number of practical disadvantages. These drawbacks have limited the success and utilization of this laser in plastic surgery. Flashscanner technology has recently been used for char-free CO2 laser surgery of the oropharynx, the external female genital tract, and perirectal mucosa. A commercially available optomechanical flashscanner unit `Swiftlase,' was adapted to a CO2 laser and used for treatment in numerous plastic surgical applications. Conditions and situations that were treated in this study included generalized neurofibromatosis, tuberous sclerosis, rhinophyma, viral warts, breast reconstruction, and deepithelialization prior to microsurgery or local flap transfer and/or skin graft placement. There were no significant wound healing complications. Some patients previously sustained undue scarring from conventional CO2 laser surgery. Conservative, primarily ablative CO2 laser surgery with the Swiftlase has usefulness for treatment of patients in plastic surgery including those that were previously unsuccessfully treated.

Catalytic Oxidation of CO for Closed-Cycle CO2 Lasers

NASA Technical Reports Server (NTRS)

Miller, I. M.; Schryer, D. R.; Hess, R. V.; Sidney, B. D.; Wood, G. M., Jr.; Paulin, P. A.; Upchurch, B. T.; Brown, K. G.

1987-01-01

Stoichiometric mixture converted completely. High-energy pulsed CO2 lasers have potential for measuring many different features of atmosphere of Earth and particularly useful on airborne or space platforms. For this application, laser must be operated in closed cycle to conserve gas, especially if rare nonradioactive isotopes of carbon and oxygen used. However, laser discharge decomposes fraction of CO2 to CO and O2, causing rapid loss in power leading to erratic behavior. To maintain operation, CO and O2 must be recombined to form CO2.

Direct laser-patterned micro-supercapacitors from paintable MoS2 films.

PubMed

Cao, Liujun; Yang, Shubin; Gao, Wei; Liu, Zheng; Gong, Yongji; Ma, Lulu; Shi, Gang; Lei, Sidong; Zhang, Yunhuai; Zhang, Shengtao; Vajtai, Robert; Ajayan, Pulickel M

2013-09-09

Micrometer-sized electrochemical capacitors have recently attracted attention due to their possible applications in micro-electronic devices. Here, a new approach to large-scale fabrication of high-capacitance, two-dimensional MoS2 film-based micro-supercapacitors is demonstrated via simple and low-cost spray painting of MoS2 nanosheets on Si/SiO2 chip and subsequent laser patterning. The obtained micro-supercapacitors are well defined by ten interdigitated electrodes (five electrodes per polarity) with 4.5 mm length, 820 μm wide for each electrode, 200 μm spacing between two electrodes and the thickness of electrode is ∼0.45 μm. The optimum MoS2 -based micro-supercapacitor exhibits excellent electrochemical performance for energy storage with aqueous electrolytes, with a high area capacitance of 8 mF cm(-2) (volumetric capacitance of 178 F cm(-3) ) and excellent cyclic performance, superior to reported graphene-based micro-supercapacitors. This strategy could provide a good opportunity to develop various micro-/nanosized energy storage devices to satisfy the requirements of portable, flexible, and transparent micro-electronic devices. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Er,CR:YSGG lasers induce fewer dysplastic-like epithelial artefacts than CO2 lasers: an in vivo experimental study on oral mucosa.

PubMed

González-Mosquera, A; Seoane, J; García-Caballero, L; López-Jornet, P; García-Caballero, T; Varela-Centelles, P

2012-09-01

Our aim was to assess wounds made by lasers (CO(2) and Er,Cr:YSGG) for their epithelial architectural changes and width of damage. We allocated 60 Sprague-Dawley(®) rats into groups: glossectomy by CO(2) laser at 3 different wattages (n=10 in each); glossectomy by Er,Cr:YSGG laser at two different emissions (n=10 in each), and a control group (n=10). Histological examination assessed both prevalence and site of thermal artefacts for each group. Both lasers (CO(2) and Er,Cr:YSGG) caused the same type of cytological artefacts. The 3W Er,Cr:YSGG laser produced the fewest cytological artefacts/specimen, and was significantly different from the other experimental groups: 3W CO(2) laser (95% CI=0.8 to 1.0); the 6W CO(2) laser (95% CI=0.1 to 2.0) and the 10W CO(2) laser (95% CI=1.1 to 3.0). CO(2) lasers (3-10W) generate epithelial damage that can simulate dysplastic changes with cytological atypia that affects mainly the basal and suprabasal layers. Irradiation with Er,CR:YSGG laser (2-4W) produces significantly fewer cellular artefacts and less epithelial damage, which may be potentially useful for biopsy of oral mucosa. Copyright © 2011 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Airborne & Ground-based measurements of atmospheric CO2 using the 1.57-μm laser absorption spectrometer

NASA Astrophysics Data System (ADS)

Sakaizawa, D.; Kawakami, S.; Nakajima, M.; Tanaka, T.; Miyamoto, Y.; Morino, I.; Uchino, O.; Asai, K.

2009-12-01

Greenhouse gases observing satellite (GOSAT) started the measurement of global CO2 abundances to reveal its continental inventory using two passive remote sensors. The goal that the sensor needs to be done is to achieve an 1% relative accuracy in order to reduce uncertainties of CO2 budget. Nevertheless, in the future global CO2 monitoring, more accurate measurement of global tropospheric CO2 abundances with the monthly regional scale are required to improve the knowledge of CO2 exchanges among the land, ocean, and atmosphere. In order to fulfill demands, a laser remote sensor, such as DIAL or laser absorption spectrometer (LAS), is a potential candidate of future space-based missions. Nowadays, those technologies are required to demonstrate an accuracy of the few-ppm level through airborne & ground-based measurements. We developed the prototype of the 1.57um LAS for a step of the next missions and perform it at the ground-based and airborne platform to show the properly validated performance in the framework of GOSAT validation. Our CO2 LAS is consisted of all optical fiber circuits & compact receiving /transmitting optics to achieve the portable, flexible and rigid system. The optical sources of on- and off-line are distributed feedback lasers, which are tuned at the strong and weak position of the R12 line in the (30012<-00001) absorption band. Their fiber coupled outputs are sinusoidal amplitude modulated by each EO devices with kHz rate and combined and amplified using an erbium doped fiber amplifier. Scattered signals from the hard target are collected by the 11cm receiving telescope and detected and stored into the laptop computer. After that, we evaluated the atmospheric CO2 density using the meteorological parameters and ratio between the on- and off-line signals. The resultant of the ground-based measurement of 3km optical length indicated that the statistical error of the path averaged atmospheric CO2 density is less than 2.8ppm with 25 minutes averaging. The variation of the path averaged atmospheric CO2 is also quite consistent with that obtained from the in-situ measurement. Airborne measurements were also performed in the end of August, 2009. In the conference we will show some characteristics among signals from clouds, the surface of the land and ocean. The weighted column CO2 density obtained from some spiral flights will be also described with some issues for the realization of the next phase space-based mission.

Remote sensing of temperature and concentration profiles of a gas jet by coupling infrared emission spectroscopy and LIDAR for characterization of aircraft engine exhaust

NASA Astrophysics Data System (ADS)

Offret, J.-P.; Lebedinsky, J.; Navello, L.; Pina, V.; Serio, B.; Bailly, Y.; Hervé, P.

2015-05-01

Temperature data play an important role in the combustion chamber since it determines both the efficiency and the rate of pollutants emission of engines. Air pollution problem concerns the emissions of gases such as CO, CO2, NO, NO2, SO2 and also aerosols, soot and volatile organic compounds. Flame combustion occurs in hostile environments where temperature and concentration profiles are often not easy to measure. In this study, a temperature and CO2 concentration profiles optical measurement method, suitable for combustion analysis, is discussed and presented. The proposed optical metrology method presents numerous advantages when compared to intrusive methods. The experimental setup comprises a passive radiative emission measurement method combined with an active laser-measurement method. The passive method is based on the use of gas emission spectroscopy. The experimental spectrometer device is coupled with an active method. The active method is used to investigate and correct complex flame profiles. This method similar to a LIDAR (Light Detection And Ranging) device is based on the measurement of Rayleigh scattering of a short laser pulse recorded using a high-speed streak camera. The whole experimental system of this new method is presented. Results obtained on a small-scale turbojet are shown and discussed in order to illustrate the potentials deliver by the sophisticated method. Both temperature and concentration profiles of the gas jet are presented and discussed.

High-quality laser cutting of stainless steel in inert gas atmosphere by ytterbium fibre and CO{sub 2} lasers

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

Golyshev, A A; Malikov, A G; Orishich, A M

Processes of cutting stainless steel by ytterbium fibre and CO{sub 2} lasers have been experimentally compared. The cut surface roughnesses for 3- and 5-mm-thick stainless steel sheets are determined. The absorption coefficient of laser radiation during cutting is measured. It is established that the power absorbed by metal during cutting by the CO{sub 2} laser exceeds that for the ytterbium laser (provided that the cutting speed remains the same). The fact that the maximum cutting speed of the CO{sub 2} laser is lower than that of the ytterbium fibre laser is explained. (laser technologies)

A Low-Level Carbon Dioxide Laser Promotes Fibroblast Proliferation and Migration through Activation of Akt, ERK, and JNK

PubMed Central

Shingyochi, Yoshiaki; Kanazawa, Shigeyuki; Tajima, Satoshi; Tanaka, Rica; Mizuno, Hiroshi; Tobita, Morikuni

2017-01-01

Background Low-level laser therapy (LLLT) with various types of lasers promotes fibroblast proliferation and migration during the process of wound healing. Although LLLT with a carbon dioxide (CO2) laser was also reported to promote wound healing, the underlying mechanisms at the cellular level have not been previously described. Herein, we investigated the effect of LLLT with a CO2 laser on fibroblast proliferation and migration. Materials and Methods Cultured human dermal fibroblasts were prepared. MTS and cell migration assays were performed with fibroblasts after LLLT with a CO2 laser at various doses (0.1, 0.5, 1.0, 2.0, or 5.0 J/cm2) to observe the effects of LLLT with a CO2 laser on the proliferation and migration of fibroblasts. The non-irradiated group served as the control. Moreover, western blot analysis was performed using fibroblasts after LLLT with a CO2 laser to analyze changes in the activities of Akt, extracellular signal-regulated kinase (ERK), and Jun N-terminal kinase (JNK), which are signaling molecules associated with cell proliferation and migration. Finally, the MTS assay, a cell migration assay, and western blot analysis were performed using fibroblasts treated with inhibitors of Akt, ERK, or JNK before LLLT with a CO2 laser. Results In MTS and cell migration assays, fibroblast proliferation and migration were promoted after LLLT with a CO2 laser at 1.0 J/cm2. Western blot analysis revealed that Akt, ERK, and JNK activities were promoted in fibroblasts after LLLT with a CO2 laser at 1.0 J/cm2. Moreover, inhibition of Akt, ERK, or JNK significantly blocked fibroblast proliferation and migration. Conclusions These findings suggested that LLLT with a CO2 laser would accelerate wound healing by promoting the proliferation and migration of fibroblasts. Activation of Akt, ERK, and JNK was essential for CO2 laser-induced proliferation and migration of fibroblasts. PMID:28045948

Efficient extreme ultraviolet plasma source generated by a CO2 laser and a liquid xenon microjet target

NASA Astrophysics Data System (ADS)

Ueno, Yoshifumi; Ariga, Tatsuya; Soumagne, George; Higashiguchi, Takeshi; Kubodera, Shoichi; Pogorelsky, Igor; Pavlishin, Igor; Stolyarov, Daniil; Babzien, Marcus; Kusche, Karl; Yakimenko, Vitaly

2007-05-01

We demonstrated efficacy of a CO2-laser-produced xenon plasma in the extreme ultraviolet (EUV) spectral region at 13.5nm at variable laser pulse widths between 200ps and 25ns. The plasma target was a 30μm liquid xenon microjet. To ensure the optimum coupling of CO2 laser energy with the plasma, they applied a prepulse yttrium aluminum garnet laser. The authors measured the conversion efficiency (CE) of the 13.5nm EUV emission for different pulse widths of the CO2 laser. A maximum CE of 0.6% was obtained for a CO2 laser pulse width of 25ns at an intensity of 5×1010W/cm2.

Reliability of Entire Corneal Thickness Mapping in Normal Post-Laser in situ Keratomileusis and Keratoconus Eyes Using Long Scan Depth Spectral Domain Optical Coherence Tomography.

PubMed

Xu, Zhe; Chen, Sisi; Yang, Chun; Huang, Shenghai; Shen, Meixiao; Wang, Yuanyuan

2018-01-01

To investigate the repeatability and reproducibility of mapping the entire corneal thickness using spectral domain optical coherence tomography (SD-OCT). Thirty normal eyes, 30 post-laser in situ keratomileusis (LASIK) surgery eyes, and 30 keratoconus eyes were analyzed. A custom-built long scan depth SD-OCT device was used to obtain entire corneal images. Ten-millimeter-diameter corneal thickness maps were generated by an automated segmentation algorithm. Intraclass correlation coefficients of repeatability (ICC1) and reproducibility (ICC2), and coefficients of repeatability (CoR1) and reproducibility (CoR2), were calculated to quantify the precision and accuracy of corneal pachymetry measurements using the Bland-Altman method. For SD-OCT measurements in healthy subjects, CoR1 and CoR2 were less than 5.00 and 5.53 μm. ICC1 and ICC2 were more than 0.997 and 0.996. For SD-OCT measurements in LASIK patients, CoR1 and CoR2 were less than 5.09 and 5.34 μm. ICC1 and ICC2 were more than 0.997 and 0.996. For SD-OCT measurements in keratoconus patients, CoR1 and CoR2 were less than 11.57 and 10.92 μm. ICC1 and ICC2 were more than 0.995 and 0.996. The measurements of corneal pachymetric mapping by long scan depth SD-OCT can be assessed over the entire corneal area with good repeatability and reproducibility. © 2017 S. Karger AG, Basel.

All fiber cladding mode stripper with uniform heat distribution and high cladding light loss manufactured by CO2 laser ablation

NASA Astrophysics Data System (ADS)

Jebali, M. A.; Basso, E. T.

2018-02-01

Cladding mode strippers are primarily used at the end of a fiber laser cavity to remove high-power excess cladding light without inducing core loss and beam quality degradation. Conventional manufacturing methods of cladding mode strippers include acid etching, abrasive blasting or laser ablation. Manufacturing of cladding mode strippers using laser ablation consist of removing parts of the cladding by fused silica ablation with a controlled penetration and shape. We present and characterize an optimized cladding mode stripper design that increases the cladding light loss with a minimal device length and manufacturing time. This design reduces the localized heat generation by improving the heat distribution along the device. We demonstrate a cladding mode stripper written on a 400um fiber with cladding light loss of 20dB, with less than 0.02dB loss in the core and minimal heating of the fiber and coating. The manufacturing process of the designed component is fully automated and takes less than 3 minutes with a very high throughput yield.

1.44-μm giant pulse generation

NASA Astrophysics Data System (ADS)

Šulc, Jan; Arátor, Pavel; Jelínková, Helena; Nejezchleb, Karel; Škoda, Václav

2007-02-01

We have compared two solid-state saturable absorbers for Q-switching of longitudinally diode-pumped Nd:YAG laser operating at wavelength 1444 nm: vanadium doped garnet (V 3+:Y 3Al IIO 5, V:YAG), and cobalt doped spinel (Co 2+:MgAl IIO 4, Co:MALO). V:YAG crystal with initial transmission 91% was 2.2mm thick. Co:MALO crystal with initial transmission 91% was 2.0mm thick. Q-switched laser consisted of the Nd:YAG composite rod (8mm long Nd-doped part, 4mm long undoped YAG part) and the saturable absorber placed in 80mm long hemispheric cavity. As an output coupler was used concave mirror (r = 150mm) with reflectivity 98% on lasing wavelength. Giant pulses were obtained with both passive Q-switches. When V:YAG saturable absorber was used, 55 ns long (FWHM) pulses were generated with peak power 0.47kW (pulse energy 26 μJ). Using Co:MALO, more powerful pulses were obtained (40 ns long, 1.0kW peak power, 45 μJ energy). Advantage of less efficient V:YAG consist in possibility of diffusion bonding between Q-switch and laser active medium which allows to prepare miniature compact laser device. This concept was demonstrated by using of Nd:YAG/V:YAG monolith crystal (4mm long undoped YAG part, 8mm long Nd:YAG part, 0.5mm long V:YAG part - initial transmission 97% @ 1444 nm). This monolithic crystal, originally designed for 1338nm lasing, was placed into 23mm long cavity resonating at wavelength 1444 nm. For output coupler reflectivity 96% pulses 39 ns long with peak power 0.64kW were generated at wavelength 1444 nm.

Receiver design, performance analysis, and evaluation for space-borne laser altimeters and space-to-space laser ranging systems

NASA Technical Reports Server (NTRS)

Davidson, Frederic M.; Sun, Xiaoli; Field, Christopher T.

1995-01-01

This Interim report consists of a manuscript, 'Receiver Design for Satellite to Satellite Laser Ranging Instrument,' and copies of two papers we co-authored, 'Demonstration of High Sensitivity Laser Ranging System' and 'Semiconductor Laser-Based Ranging Instrument for Earth Gravity Measurements. ' These two papers were presented at the conference Semiconductor Lasers, Advanced Devices and Applications, August 21 -23, 1995, Keystone Colorado. The manuscript is a draft in the preparation for publication, which summarizes the theory we developed on space-borne laser ranging instrument for gravity measurements.

CO2 and diode laser for excisional biopsies of oral mucosal lesions. A pilot study evaluating clinical and histopathological parameters.

PubMed

Suter, Valérie G A; Altermatt, Hans Jörg; Sendi, Pedram; Mettraux, Gérald; Bornstein, Michael M

2010-01-01

The present pilot study evaluates the histopathological characteristics and suitability of CO2 and diode lasers for performing excisional biopsies in the buccal mucosa with special emphasis on the extent of the thermal damage zone created. 15 patients agreed to undergo surgical removal of their fibrous hyperplasias with a laser. These patients were randomly assigned to one diode or two CO2 laser groups. The CO2 laser was used in a continuous wave mode (cw) with a power of 5 W (Watts), and in a pulsed char-free mode (cf). Power settings for the diode laser were 5.12 W in a pulsed mode. The thermal damage zone of the three lasers and intraoperative and postoperative complications were assessed and compared. The collateral thermal damage zone on the borders of the excisional biopsies was significantly smaller with the CO, laser for both settings tested compared to the diode laser regarding values in pm or histopathological index scores. The only intraoperative complication encountered was bleeding, which had to be controlled with electrocauterization. No postoperative complications occurred in any of the three groups. The CO2 laser seems to be appropriate for excisional biopsies of benign oral mucosal lesions. The CO2 laser offers clear advantages in terms of smaller thermal damage zones over the diode laser. More study participants are needed to demonstrate potential differences between the two different CO2 laser settings tested.

Multistaged stokes injected Raman capillary waveguide amplifier

DOEpatents

Kurnit, Norman A.

1980-01-01

A multistaged Stokes injected Raman capillary waveguide amplifier for providing a high gain Stokes output signal. The amplifier uses a plurality of optically coupled capillary waveguide amplifiers and one or more regenerative amplifiers to increase Stokes gain to a level sufficient for power amplification. Power amplification is provided by a multifocused Raman gain cell or a large diameter capillary waveguide. An external source of CO.sub.2 laser radiation can be injected into each of the capillary waveguide amplifier stages to increase Raman gain. Devices for injecting external sources of CO.sub.2 radiation include: dichroic mirrors, prisms, gratings and Ge Brewster plates. Alternatively, the CO.sub.2 input radiation to the first stage can be coupled and amplified between successive stages.

[Efficacy of CO2 laser in the treatment of precancerous laryngeal lesions under phonomicrosurgery and its relative factors].

PubMed

Gu, Qingjia; Feng, Yong; Yu, Xiaoxu; Fan, Jian'gang; Li, Debing; He, Gang

2014-08-01

To investigate the efficacy of CO2 laser treatment for patients with precancerous laryngeal lesions under phonomicrosurgery and to explore the points for attention in operation. They were all treated with phonomicrosurgery techniques as mucosal epitheliumablation or mucosal stripping by using CO2 laser. Eight patients with laryngeal papilloma were excised by CO2 laser. All patients were treated with CO2 laser surgery successfully. During follow-up of 6 to 39 months, all patients survived. Local recurrence or canceration were detected in 3 cases, of which 2 cases with laryngeal papilloma underwent CO2 laser treatment in one year post-operatively, while the other case with severe dysplasia underwent laryngeal vertical partial laryngectomy and post-operative radiotherapy one and half year postoperatively due to canceration. No local recurrence occurred until the last follow up. No severe complications such as dyspnea and hemorrhage occured. CO2 laser surgery is an effective and minimally invasive treatment for precancerous laryngeal lesions. Through selecting the appropriate patient and paying attention to the operation during surgery, the adhesion of vocal cord can be reduced or even be avoided after CO2 laser surgery.

[Combined CO2 and Nd-YAG laser in neurosurgical practice. A 1st experience apropos of 40 intracranial procedures].

PubMed

Roux, F X; Leriche, B; Cioloca, C; Devaux, B; Turak, B; Nohra, G

1992-01-01

The authors present their experience concerning the use of Combolaser (Lasermatic, Finland), in neurosurgery. This laser-unit combines two wavelengths (CO2 and 1.06 Nd-YAG) which are emitted simultaneously and coaxially. During the last 12 months, 40 patients harbouring an intracranial tumor were operated upon with such a combolaser unit: 8 infra-tentorial, 32 supra-tentorial, 17 were meningiomas. The mean output power used during the procedures was 3-5 w for both CO2 and Nd-YAG beams. The authors discuss the advantages and inconveniences of such a laser; and they compare it with the other laser-units they have been using for the last 10 years: CO2-Laser, 1.06 Nd-YAG and 1.32 Nd-YAG laser. The main inconvenience of this unit is linked to the utilization of the articulated arm which conducts the CO2 laser beam. This drawback should be avoided or limited by the use of a fiber microguide, which will conduct both CO2 and Nd-YAG beams simultaneously. The principal contribution of a combined-laser unit is the quality of the haemostasis associated to a very good vaporization and cutting effect. When both wavelengths are synchronized, the combined laser beams penetrate into the nervous parenchyma more deeply than the only CO2 laser beam would with the same parameters. The vaporization effect is identical to that obtained with the isolated CO2 laser; the quality of haemostasis is limited to the effects of the Nd-YAG laser. Another advantage must be emphasized: the possibility of utilizing separately the CO2 laser and the 1.06 Nd-YAG.

Intraoral laser welding: ultrastructural and mechanical analysis to compare laboratory laser and dental laser.

PubMed

Fornaini, Carlo; Passaretti, Francesca; Villa, Elena; Rocca, Jean-Paul; Merigo, Elisabetta; Vescovi, Paolo; Meleti, Marco; Manfredi, Maddalena; Nammour, Samir

2011-07-01

The Nd:YAG laser has been used since 1970 in dental laboratories to weld metals on dental prostheses. Recently in several clinical cases, we have suggested that the Nd:YAG laser device commonly utilized in the dental office could be used to repair broken fixed, removable and orthodontic prostheses and to weld metals directly in the mouth. The aim of this work was to evaluate, using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and dynamic mechanical analysis (DMA), the quality of the weld and its mechanical strength, comparing a device normally used in dental laboratory and a device normally used in the dental office for oral surgery, the same as that described for intraoral welding. Metal plates of a Co-Cr-Mo dental alloy and steel orthodontic wires were subjected to four welding procedures: welding without filler metal using the laboratory laser, welding with filler metal using the laboratory laser, welding without filler metal using the office laser, and welding with filler metal using the office laser. The welded materials were then analysed by SEM, EDS and DMA. SEM analysis did not show significant differences between the samples although the plates welded using the office laser without filler metal showed a greater number of fissures than the other samples. EDS microanalysis of the welding zone showed a homogeneous composition of the metals. Mechanical tests showed similar elastic behaviours of the samples, with minimal differences between the samples welded with the two devices. No wire broke even under the maximum force applied by the analyser. This study seems to demonstrate that the welds produced using the office Nd:YAG laser device and the laboratory Nd:YAG laser device, as analysed by SEM, EDS and DMA, showed minimal and nonsignificant differences, although these findings need to be confirmed using a greater number of samples.

Method and apparatus for fast laser-pulse detection using gaseous plasmas

DOEpatents

McLellan, E.J.; Webb, J.A.

1981-06-18

The method and device of the instant invention is a detector of pulsed laser radiation which utilizes the electromotive force generated by the plasma formed when such radiation is focused onto a surface. Measurements are made with a 10.6 ..mu..m CO/sub 2/ laser capable of producing peak intensities of 10/sup 13/ W/cm/sup 2/ when directed through a converging lens. Evacuated detector response to such laser intensity if 1 kV signal peak amplitude and subnanosecond risetimes into a 50 ..cap omega.. load. Detector performance is found to be greatly altered with the introduction of a background gas. For example, with one atmosphere of air, the detector produces prompt signals of the order of 1 V with subnanosecond response for pulse trains lasting 100 ns. With argon, krypton, or zenon at pressures of the order of 10 torr, the detector generates trigger pulses of about 250 V amplitude and 0.2 ns risetimes. Such detectors are quite robust when irradiated with high intensity laser radiation and are useful for qualitative laser beam monitoring.

Conversion of blackbody radiation into laser energy

NASA Technical Reports Server (NTRS)

Mcinville, R. M.; Hassan, H. A.

1982-01-01

By employing detailed kinetic models, three concepts which utilize a blackbody cavity for the conversion of solar energy into laser energy using a CO2 lasant are analyzed and compared. In the first, the blackbody radiation is used to excite flowing CO2 directly. The second and third employ a mixing laser concept with CO and N2 being the donor gases. The CO is optically pumped while thermal heating excites the N2. Blackbody temperatures ranging from 1500 deg K - 2500 deg K are considered. Based on calculated laser power output per unit flow rate of CO2, it appears that the N2-CO2 mixing laser is the most attractive system.

Use of a microsecond Er:YAG laser in laryngeal surgery reduces collateral thermal injury in comparison to superpulsed CO2 laser.

PubMed

Böttcher, Arne; Jowett, Nathan; Kucher, Stanislav; Reimer, Rudolph; Schumacher, Udo; Knecht, Rainald; Wöllmer, Wolfgang; Münscher, Adrian; Dalchow, Carsten V

2014-05-01

Despite causing significant thermocoagulative insult, use of the carbon dioxide (CO2) laser is considered gold standard in surgery for early stage larynx carcinoma. Limited attention has been paid to the use of the erbium:yttrium-aluminium-garnet (Er:YAG) laser in laryngeal surgery as a means to reduce thermal tissue injury. The objective of this study is to compare the extent of thermal injury and precision of vocal fold incisions made using microsecond Er:YAG and superpulsed CO2 lasers. In the optics laboratory ex vivo porcine vocal folds were incised using Er:YAG and CO2 lasers. Lateral epithelial and subepithelial thermal damage zones and cutting gap widths were histologically determined. Environmental scanning electron microscopy (ESEM) images were examined for signs of carbonization. Temperature rise during Er:YAG laser incisions was determined using infrared thermography (IRT). In comparison to the CO2 laser, Er:YAG laser incisions showed significantly decreased epithelial (236.44 μm) and subepithelial (72.91 μm) damage zones (p < 0.001). Cutting gaps were significantly narrower for CO2 (878.72 μm) compared to Er:YAG (1090.78 μm; p = 0.027) laser. ESEM revealed intact collagen fibres along Er:YAG laser cutting edges without obvious carbonization, in comparison to diffuse carbonization and tissue melting seen for CO2 laser incisions. IRT demonstrated absolute temperature rise below 70 °C for Er:YAG laser incisions. This study has demonstrated significantly reduced lateral thermal damage zones with wider basal cutting gaps for vocal fold incisions made using Er:YAG laser in comparison to those made using CO2 laser.

A cesium TELEC experiment at Lewis Research Center

NASA Technical Reports Server (NTRS)

Britt, E. J.

1979-01-01

The thermoelectronic laser energy converter (TELEC), was studied as a method of converting a 10.6 mm CO2 laser beam into electric power. The calculated characteristics of a TELEC seem to be well matched to the requirements of a spacecraft laser energy conversion system. The TELEC is a high power density plasma device which absorbs an intense laser beam by inverse bremsstrahlung with the plasma electrons. In the TELEC process, electromagnetic radiation is absorbed directly in the plasma electrons producing a high electron temperature. The energetic electrons diffuse out of the plasma striking two electrodes which are in contact with the plasma at the boundaries. These two electrodes have different areas: the larger one is designated as the collector, the smaller one is designated as the emitter. The smaller electrode functions as an electron emitter to provide continuity of the current. Waste heat is rejected from the collector electrode. An experiment was carried out with a high power laser using a cesium vapor TELEC cell with 30 cm active length. Laser supported plasma was produced in the TELEC device during a number of laser runs over a period of several days. Electric power from the TELEC was observed with currents in the range of several amperes and output potentials of less than 1 volt. The magnitudes of these electric outputs were smaller than anticipated but consistent with the power levels of the laser during this experiment.

Clinical effects of CO2 laser on equine diseases

NASA Astrophysics Data System (ADS)

Lindholm, Arne; Svensson, Ulf; Collinder, Eje

2002-10-01

CO2 lasers has been used for five years at Malaren Equine Hospital, as an alternative treatment of some equine diseases. The application of CO2 laser has been studied for evaluation of its appropriateness for treatment of the equine diseases sarcoids, lameness in fetlock joints or pulmonary haemorrhage. During the last five years, above 100 equine sarcoids have been removed by laser surgery (CO2 laser) and so far resulting in significantly few recurrences compared with results from usual excision surgery. In one study, acute traumatic arthritis in fetlock joints was treated three times every second day with defocalised CO2 laser. The therapeutic effectiveness of CO2 laser in this study was better than that of the customary therapy with betamethasone plus hyaluronan. During one year, chronic pulmonary bleeders, namely exercise induced pulmonary haemorrhage, has been treated with defocalised CO2 laser. Six race horses have been treated once daily during five days. Until now, three of these horses have subsequently been successfully racing and no symptoms of pulmonary haemorrhage have been observed. These studies indicate that CO2 laser might be an appropriate therapy on sarcoids and traumatic arthritis, and probably also on exercise induced pulmonary haemorrhage. Other treatments for this pulmonary disease are few.

Extension of spectral range of Peltier cooled photodetectors to 16 μm

NASA Astrophysics Data System (ADS)

Piotrowski, A.; Piotrowski, J.; Gawron, W.; Pawluczyk, J.; Pedzinska, M.

2009-05-01

We have developed various types of photodetectors operating without cryocooling. Initially, the devices were mostly used for uncooled detection of CO2 laser radiation. Over the years the performance and speed of response has been steadily improved. At present the uncooled or Peltier cooled photodetectors can be used for sensitive and fast response detection in the MWIR and LWIR spectral range. The devices have found important applications in IR spectrometry, quantum cascade laser based gas analyzers, laser radiation alerters and many other IR systems. Recent efforts were concentrated on the extension of useful spectral range to >13 μm, as required for its application in FTIR spectrometers. This was achieved with improved design of the active elements, use of monolithic optical immersion technology, enhanced absorption of radiation, dedicated electronics, series connection of small cells in series, and last but not least, applying more efficient Peltier coolers. Practical devices are based on the complex HgCdTe heterostructures grown on GaAs substrates with MOCVD technique with immersion lens formed by micromachining in the GaAs substrates. The results are very encouraging. The devices cooled with miniature 4 stage Peltier coolers mounted in TO-8 style housings show significant response at wavelength exceeding 16 μm.

Laser-bulge based ultrasonic bonding method for fabricating multilayer thermoplastic microfluidic devices

NASA Astrophysics Data System (ADS)

Liang, Chao; Liu, Chong; Liu, Ziyang; Meng, Fanjian; Li, Jingmin

2017-11-01

Ultrasonic bonding is a commonly-used method for fabrication of thermoplastic microfluidic devices. However, due to the existence of the energy director (a convex structure to concentrate the ultrasonic energy), it is difficult to control its molten polymer flow, which may result in a small gap between the bonding interface or microchannel clogging. In this paper, we present an approach to address these issues. Firstly, the microchannels were patterned onto the PMMA sheets using hot embossing with the wire electrical discharge machined molds. Then, a small bulge, which was formed at the edge of the laser-ablated groove (LG), was generated around the microchannel using a CO2 laser ablation system. By using the bulge to concentrate the ultrasonic energy, there was no need for fabricating the complicated and customized energy director. When the bulge was melted, it was able to flow into the LG which overcame the ‘gap’ and ‘clogging’ problems. Here, two types of two-layer microfluidic devices and a five-layer micromixer were fabricated to validate its performance. Our results showed that these thermoplastic microdevices can be successfully bonded by using this method. The liquid leakage was not observed in both the capillary-driven flowing test and the pressure-driven mixing experiments. It is a potential method for bonding the thermoplastic microfluidic devices.

Improved detection of highly energetic materials traces on surfaces by standoff laser-induced thermal emission incorporating neural networks

NASA Astrophysics Data System (ADS)

Figueroa-Navedo, Amanda; Galán-Freyle, Nataly Y.; Pacheco-Londoño, Leonardo C.; Hernández-Rivera, Samuel P.

2013-05-01

Terrorists conceal highly energetic materials (HEM) as Improvised Explosive Devices (IED) in various types of materials such as PVC, wood, Teflon, aluminum, acrylic, carton and rubber to disguise them from detection equipment used by military and security agency personnel. Infrared emissions (IREs) of substrates, with and without HEM, were measured to generate models for detection and discrimination. Multivariable analysis techniques such as principal component analysis (PCA), soft independent modeling by class analogy (SIMCA), partial least squares-discriminant analysis (PLS-DA), support vector machine (SVM) and neural networks (NN) were employed to generate models, in which the emission of IR light from heated samples was stimulated using a CO2 laser giving rise to laser induced thermal emission (LITE) of HEMs. Traces of a specific target threat chemical explosive: PETN in surface concentrations of 10 to 300 ug/cm2 were studied on the surfaces mentioned. Custom built experimental setup used a CO2 laser as a heating source positioned with a telescope, where a minimal loss in reflective optics was reported, for the Mid-IR at a distance of 4 m and 32 scans at 10 s. SVM-DA resulted in the best statistical technique for a discrimination performance of 97%. PLS-DA accurately predicted over 94% and NN 88%.

A numerical simulation of machining glass by dual CO 2-laser beams

NASA Astrophysics Data System (ADS)

Jiao, Junke; Wang, Xinbing

2008-03-01

In the flat panel display (FPD) industry, lasers may be used to cut glass plates. In order to reduce the possibility of fracture in the process of cutting glass by lasers, the thermal stress has to be less than the critical rupture strength. In this paper, a dual-laser-beam method is proposed, where an off-focus CO 2-laser beam was used to preheat the glass sample to reduce the thermal gradients and a focused CO 2-laser beam was used to machine the glass. The distribution of the thermal stress and the temperature was simulated by using finite element analysis software, Ansys. The thermal stress was studied both when the glass sample was machined by a single CO 2-laser beam and by dual CO 2-laser beams. It was concluded that the thermal stress can be reduced by means of the dual-laser-beam method.

Application of CO laser for laser balloon angioplasty

NASA Astrophysics Data System (ADS)

Miyamoto, Akira; Sakurada, Masami; Mizuno, Kyoichi; Kurita, Akira; Nakamura, Haruo; Suda, Akira; Arai, Tsunenori; Kikuchi, Makoto

1990-07-01

CO laser may be efficient for thermal fusion of intima of arterial wall without adventitial tissue damage because of high tissue absorption. To investigate the efficacy of CO laser as a laser bam for laser balloon angioplasty (LBA). CO laser was irradiated to aortic tissue through 3Oim polyethylene membrane and tissue temperature was measured by a thermistor. At 2Owatt/cm2 200joules/cm2 continuous laser exposure (CE), tissue temperature was above 100°C within a depth of 1mm and rapidly decreased to 60 °C or below between 2 and 3mm in depth. Moreover, adventitial temperature could be decreased by changing duty ratio (exposure duration/interval) of intermittent laser exposure (IE) despite of the same laser energy. Light microscopy showed high degree of medial coagulation necrosis in CE, however thermal coagulation was observed only at the surface of intima of aortic tissue in IE at duty ratio 1 / 2. These findings suggested CO laser could coagulate intimal layer with less deep thermal damage compared to Nd- YAG laser and that IE was better for superficial welding than CE at the same energy. We concluded that CO laser might be more efficient as a laser beam for LBA than Nd-YAG laser.

In situ study of the anticariogenic potential of fluoride varnish combined with CO2 laser on enamel.

PubMed

Souza-Gabriel, Aline Evangelista; Turssi, Cecília Pedroso; Colucci, Vivian; Tenuta, Lívia Maria Andaló; Serra, Mônica Campos; Corona, Silmara Aparecida Milori

2015-06-01

This in situ study evaluated the effect of fluoride varnish combined with CO2 laser in controlling enamel demineralization caused by cariogenic challenges. In a crossover study conducted in 2 phases of 14 days each, 14 volunteers (n = 14) wore palatal appliances with bovine enamel slabs treated with fluoride varnish + CO2 laser (FV + CO2), fluoride varnish (FV), nonfluoride placebo varnish (PV) and nonfluoride placebo varnish + CO2 laser (PV + CO2). Drops of sucrose solution were dripped onto enamel slabs allowing the accumulation of biofilm. At the first phase, half of the volunteers received 4 enamel slabs treated with FV while the remainders received slabs exposed to the PV with and without CO2 laser. In the second phase, the vonlunteers were reversed treatments. The slabs were evaluated for cross-sectional microhardness (CSMH) and the concentration of loosely bound fluoride (CaF2) and firmly bound fluoride (FAp). The concentration of fluoride in biofilm were also determined. Two-way ANOVA showed that the CSMH values were higher in laser-irradiated enamel, regardless of the fluoride varnish. Friedman test showed that FV group presented significantly larger amount of fluoride in biofilm (P < 0.05). In the enamel, the largest amount of fluoride was found in the groups FV + CO2, which was not different from FV (P > 0.05). The synergistic effect of fluoride varnish and CO2 laser on enamel demineralization was not observed, however, CO2 laser reduces enamel demineralization. CO2 laser might reduce the demineralization of subsurface enamel, although its association with a high concentrated fluoride therapy may not result in a positive synergistic interaction. Copyright © 2015 Elsevier Ltd. All rights reserved.

High level active n+ doping of strained germanium through co-implantation and nanosecond pulsed laser melting

NASA Astrophysics Data System (ADS)

Pastor, David; Gandhi, Hemi H.; Monmeyran, Corentin P.; Akey, Austin J.; Milazzo, Ruggero; Cai, Yan; Napolitani, Enrico; Gwilliam, Russell M.; Crowe, Iain F.; Michel, Jurgen; Kimerling, L. C.; Agarwal, Anuradha; Mazur, Eric; Aziz, Michael J.

2018-04-01

Obtaining high level active n+ carrier concentrations in germanium (Ge) has been a significant challenge for further development of Ge devices. By ion implanting phosphorus (P) and fluorine (F) into Ge and restoring crystallinity using Nd:YAG nanosecond pulsed laser melting (PLM), we demonstrate 1020 cm-3 n+ carrier concentration in tensile-strained epitaxial germanium-on-silicon. Scanning electron microscopy shows that after laser treatment, samples implanted with P have an ablated surface, whereas P + F co-implanted samples have good crystallinity and a smooth surface topography. We characterize P and F concentration depth profiles using secondary ion mass spectrometry and spreading resistance profiling. The peak carrier concentration, 1020 cm-3 at 80 nm below the surface, coincides with the peak F concentration, illustrating the key role of F in increasing donor activation. Cross-sectional transmission electron microscopy of the co-implanted sample shows that the Ge epilayer region damaged during implantation is a single crystal after PLM. High-resolution X-ray diffraction and Raman spectroscopy measurements both indicate that the as-grown epitaxial layer strain is preserved after PLM. These results demonstrate that co-implantation and PLM can achieve the combination of n+ carrier concentration and strain in Ge epilayers necessary for next-generation, high-performance Ge-on-Si devices.

Clinical efficacy of utilizing Ultrapulse CO2 combined with fractional CO2 laser for the treatment of hypertrophic scars in Asians-A prospective clinical evaluation.

PubMed

Lei, Ying; Li, Shi Feng; Yu, Yi Ling; Tan, Jun; Gold, Michael H

2017-06-01

Hypertrophic scarring is seen regularly. Tissue penetration of laser energy into hypertrophic scars using computer defaults from some lasers may be insufficient and penetration not enough. We have developed a treatment with an interrupted laser "drilling" by the Ultrapulse CO 2 (Manual Fractional Technology, MFT) and, a second pass, with fractional CO 2 . The MFT with fractional CO 2 lasers to treat hypertrophic scars is evaluated. A total of 158 patients with hypertrophic scars had three sessions of MFT with fractional CO 2 laser at 3-month intervals. Evaluations made before and 6 months after the 3rd treatment: (1) the Vancouver Scar Scale (VSS), (2) the University of North Carolina (UNC) Scar Scale, and (3) a survey of patient satisfaction. All data were analyzed using a t-test before and after treatment. The VSS score decreased from 9.35 to 3.12 (P<.0001), and the UNC Scar Scale score decreased from 8.03 to 1.62 (P<.0001). The overall satisfaction rate was 92%. No long-term complications occurred in the clinical trial. The interrupted laser drilling by MFT and a fractional CO2 laser had profound effects on the hypertrophic scars treated. It works by increasing the penetration depth of the CO 2 laser in the scar tissue, exerting more precise effects on the hypertrophic scars. MFT combined with fractional CO 2 laser has the potential to be a major advance in the treatment of hypertrophic scars. © 2017 Wiley Periodicals, Inc.

The choice: Welding with CO2 or Nd:YAG lasers

NASA Astrophysics Data System (ADS)

Leong, Keng H.

The recent commercial availability of multi-kilowatt Nd:YAG lasers has opened new avenues for rapid laser processing as well as intensified the competition (cost effectiveness) between CO2 and Nd:YAG laser systems. Vendors offering Nd:YAG laser systems may claim lower operating costs (than CO2) and fiberoptic beam delivery flexibility while CO2 systems vendors may emphasize lower capital cost and well established processing requirements and experience. The capital and operating costs of a laser system are impacted by demand and supply economics and technological advances. Frequently the total cost of a workcell using a laser for processing has to be considered rather than the laser system alone. Consequently it is not very practical to approach the selection of a laser system based on its capital cost and estimated operating cost only. This presentation describes a more pragmatic approach to aid the user in the selection of the optimal multi-kilowatt laser system for a particular processing requirement with emphasis on welding. CO2 laser systems are well established on the factory floor. Consequently, emphasis is given to the comparative application of Nd:YAG lasers, process requirements and performance. Requirements for the laser welding of different metals are examined in the context of hardware (laser system and beam delivery) selection and examples of welding speeds that can be achieved using CO2 and Nd:YAG lasers are examined.

Comparison of separation performance of laser-ablated and wet-etched microfluidic devices

PubMed Central

Baker, Christopher A.; Bulloch, Rayford; Roper, Michael G.

2010-01-01

Laser ablation of glass allows for production of microfluidic devices without the need of hydrofluoric acid and photolithography. The goal of this study was to compare the separation performance of microfluidic devices produced using a low-cost laser ablation system and conventional wet etching. During laser ablation, cracking of the glass substrate was prevented by heating the glass to 300°C. A range of laser energy densities was found to produce channel depths ranging from 4 – 35 μm and channel widths from 118 – 162 μm. The electroosmotic flow velocity was lower in laser-ablated devices, 0.110 ± 0.005 cm s−1, as compared to wet-etched microfluidic chips, 0.126 ± 0.003 cm s−1. Separations of both small and large molecules performed on both wet- and laser-ablated devices were compared by examining limits of detection, theoretical plate count, and peak asymmetry. Laser-induced fluorescence detection limits were 10 pM fluorescein for both types of devices. Laser-ablated and wet-etched microfluidic chips had reproducible migration times with ≤ 2.8% RSD and peak asymmetries ranging from 1.0 – 1.8. Numbers of theoretical plates were between 2.8- and 6.2-fold higher on the wet-etched devices compared to laser-ablated devices. Nevertheless, resolution between small and large analytes was accomplished, which indicates that laser ablation may find an application in pedagogical studies of electrophoresis or microfluidic devices, or in settings where hydrofluoric acid cannot be used. PMID:20827468

Polarization characteristic of a room-temperature Co:MgF2 laser.

PubMed

Zhang, Zengming M; Cui, Yiben B; Li, Fuli L; Zhang, Guobin B; Pu, Qirong R; Xu, Gaojie J

2002-02-20

A study of the polarization characteristic of a Co:MgF2 laser with a 1320-nm YAG pumping laser at room temperature is reported. The thresholds, output energies, and efficiencies of the laser are given at the various polarization states. The more intensive emission is in the pi-polarization pump laser and sigma-polarization laser operation. Performances of the Co:MgF2 lasers are similar for the polarized and unpolarized laser pumping along the optical axis of the crystal.

Technology assessment of high pulse energy CO(2) lasers for remote sensing from satellites

NASA Technical Reports Server (NTRS)

Hess, R. V.; Brockman, P.; Schryer, D. R.; Miller, I. M.; Bair, C. H.; Sidney, B. D.; Wood, G. M.; Upchurch, B. T.; Brown, K. G.

1985-01-01

Developments and needs for research to extend the lifetime and optimize the configuration of CO2 laser systems for satellite based on remote sensing of atmospheric wind velocities and trace gases are reviewed. The CO2 laser systems for operational satellite application will require lifetimes which exceed 1 year. Progress in the development of efficient low temperature catalysts and gas mixture modifications for extending the lifetime of high pulse energy closed cycle common and rare isotope CO2 lasers and of sealed CW CO2 lasers is reviewed. Several CO2 laser configurations are under development to meet the requirements including: unstable resonators, master oscillator power amplifiers and telescopic stable resonators, using UV or E-beam preionization. Progress in the systems is reviewed and tradeoffs in the system parameters are discussed.

Perovskite Materials for Light-Emitting Diodes and Lasers.

PubMed

Veldhuis, Sjoerd A; Boix, Pablo P; Yantara, Natalia; Li, Mingjie; Sum, Tze Chien; Mathews, Nripan; Mhaisalkar, Subodh G

2016-08-01

Organic-inorganic hybrid perovskites have cemented their position as an exceptional class of optoelectronic materials thanks to record photovoltaic efficiencies of 22.1%, as well as promising demonstrations of light-emitting diodes, lasers, and light-emitting transistors. Perovskite materials with photoluminescence quantum yields close to 100% and perovskite light-emitting diodes with external quantum efficiencies of 8% and current efficiencies of 43 cd A(-1) have been achieved. Although perovskite light-emitting devices are yet to become industrially relevant, in merely two years these devices have achieved the brightness and efficiencies that organic light-emitting diodes accomplished in two decades. Further advances will rely decisively on the multitude of compositional, structural variants that enable the formation of lower-dimensionality layered and three-dimensional perovskites, nanostructures, charge-transport materials, and device processing with architectural innovations. Here, the rapid advancements in perovskite light-emitting devices and lasers are reviewed. The key challenges in materials development, device fabrication, operational stability are addressed, and an outlook is presented that will address market viability of perovskite light-emitting devices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Diatomic gasdynamic lasers.

NASA Technical Reports Server (NTRS)

Mckenzie, R. L.

1972-01-01

Predictions from a numerical model of the vibrational relaxation of anharmonic diatomic oscillators in supersonic expansions are used to show the extent to which the small anharmonicity of gases like CO can cause significant overpopulations of upper vibrational states. When mixtures of CO and N2 are considered, radiative gain on many of the vibration-rotation transitions of CO is predicted. Experiments are described that qualitatively verify the predictions by demonstrating laser oscillation in CO-N2 expansions. The resulting CO-N2 gasdynamic laser displays performance characteristics that equal or exceed those of similar CO2 lasers.

Diatomic gasdynamic lasers

NASA Technical Reports Server (NTRS)

Mckenzie, R. L.

1971-01-01

Predictions from a numerical model of the vibrational relaxation of anharmonic diatomic oscillators in supersonic expansions are used to show the extent to which the small anharmonicity of gases like CO can cause significant overpopulations of upper vibrational states. When mixtures of CO and N2 are considered, radiative gain on many of the vibration-rotation transitions of CO is predicted. Experiments are described that qualitatively verify the predictions by demonstrating laser oscillation in CO-N2 expansions. The resulting CO-N2 gasdynamic laser displays performance characteristics that equal or exceed those of similar CO2 lasers.

Comparative study of upper lip frenectomy with the CO2 laser versus the Er, Cr: YSGG laser

PubMed Central

Pié-Sánchez, Jordi; España-Tost, Antonio J.; Arnabat-Domínguez, Josep

2012-01-01

Objectives: To compare upper lip frenulum reinsertion, bleeding, surgical time and surgical wound healing in frenectomies performed with the CO2 laser versus the Er, Cr:YSGG laser. Study design: A prospective study was carried out on 50 randomized pediatric patients who underwent rhomboidal resection of the upper lip frenulum with either the CO2 laser or the Er,Cr:YSGG laser. Twenty-five patients were assigned to each laser system. All patients were examined at 7, 14, 21 days and 4 months after the operation in order to assess the surgical wound healing. Results: Insertion of the frenulum, which was preoperatively located between the upper central incisors, migrated to the mucogingival junction as a result of using both laser systems in all patients. Only two patients required a single dose of 650 mg of paracetamol, one of either study group. CO2 laser registered improved intraoperative bleeding control results and shorter surgical times. On the other hand, the Er,Cr:YSGG laser achieved faster healing. Conclusions: Upper lip laser frenectomy is a simple technique that results in minimum or no postoperative swelling or pain, and which involves upper lip frenulum reinsertion at the mucogingival junction. The CO2 laser offers a bloodless field and shorter surgical times compared with the Er,Cr:YSGG laser. On the other hand, the Er,Cr:YSGG laser achieved faster wound healing. Key words:Frenectomy, upper lip frenulum, CO2 laser, Er,Cr:YSGG laser, laser. PMID:22143683

High power CO2 coherent ladar haven't quit the stage of military affairs

NASA Astrophysics Data System (ADS)

Zhang, Heyong

2015-05-01

The invention of the laser in 1960 created the possibility of using a source of coherent light as a transmitter for a laser radar (ladar). Coherent ladar shares many of the basic features of more common microwave radars. However, it is the extremely short operating wavelength of lasers that introduces new military applications, especially in the area of missile identification, space target tracking, remote rang finding, camouflage discrimination and toxic agent detection. Therefore, the most popular application field such as laser imaging and ranging were focused on CO2 laser in the last few decades. But during the development of solid state and fiber laser, some people said that the CO2 laser will be disappeared and will be replaced by the solid and fiber laser in the field of military and industry. The coherent CO2 laser radar will have the same destiny in the field of military affairs. However, to my opinion, the high power CO2 laser will be the most important laser source for laser radar and countermeasure in the future.

Rapid identification of macro nutrients in pharmaceutical medicine using laser-induced plasma spectroscopy

NASA Astrophysics Data System (ADS)

Khumaeni, Ali; Sugito, Heri; Yoyo Wardaya, Asep; Setia Budi, Wahyu

2018-05-01

Identification of macro nutrients in medicine is really necessary for healthy purpose. In this study, identification of macro elements in pharmaceutical products was carried out by laser-induced plasma spectroscopy (LIPS). A comparative study was made by employing different types of laser, namely an Nd:YAG laser and a pulse TEA CO2 laser. Experimentally, the laser beam was directed and focused by a convex lens on a mineral supplement tablet. A luminous plasma was induced on the tablet’s surface. Sharp and high-intensity emission spectra of macro elements including Ca and Mg were detected both in LIBS using Nd:YAG and pulse CO2 lasers. However, the intensities of Ca and Mg spectra are much higher for the LIBS using CO2 laser. Based on the analysis, the plasma temperature plays important role in the spectra. Namely, the plasma induced by a TEA CO2 laser is much higher than that of Nd:YAG laser; the plasma temperature for the case of TEA CO2 laser and Nd:YAG laser were 6400 K and 4500 K, respectively.

Design of catalytic monoliths for closed-cycle carbon dioxide lasers

NASA Technical Reports Server (NTRS)

Herz, R. K.; Guinn, K.; Goldblum, S.; Noskowski, E.

1989-01-01

Pulsed carbon dioxide (CO2) lasers have many applications in aeronautics, space research, weather monitoring and other areas. Full exploitation of the potential of these lasers in hampered by the dissociation of CO2 that occurs during laser operation. The development of closed-cycle CO2 lasers requires active CO-O2 recombination (CO oxidation) catalyst and design methods for implementation of catalysts in CO2 laser systems. A monolith catalyst section model and associated design computer program, LASCAT, are presented to assist in the design of a monolith catalyst section of a closed cycle CO2 laser system. Using LASCAT,the designer is able to specify a number of system parameters and determine the monolith section performance. Trade-offs between the catalyst activity, catalyst dimensions, monolith dimensions, pressure drop, O2 conversion, and other variables can be explored and adjusted to meet system design specifications. An introduction describes a typical closed-cycle CO2 system, and indicates some advantages of a closed cycle laser system over an open cycle system and some advantages of monolith support over other types of supports. The development and use of a monolith catalyst model is presented. The results of a design study and a discussion of general design rules are given.

Carbon dioxide laser fiber for the excision of oral leukoplakia.

PubMed

Chee, Michael; Sasaki, Clarence

2013-09-01

We compared the efficacies of cold knife excision and carbon dioxide (CO2) laser fiber excision of oral cavity leukoplakia. Between August 2009 and June 2011,45 patients who underwent excision of oral cavity leukoplakia were assessed for operative time, use of bipolar cautery, blood loss, and number of intraoperative margins needed. Patients were assigned randomly to either a cold knife group (23 procedures) or a CO2 laser fiber group (24 procedures) at the time of the procedure. The times of excision were similar in the CO2 laser fiber group (1.64 min/cm2) and the cold knife group (1.70 min/cm2). There were large differences between the CO2 laser fiber group and the cold knife group in the categories of bipolar cautery uses per square centimeter (0.34 uses versus 3.32 uses) and blood loss (0.19 g/cm2 versus 2.55 g/cm2). The average number of margins needed to clear a specimen by frozen section was 1.21 for the CO2 laser fiber group and 1.83 for the cold knife group. The CO2 laser fiber did not show an advantage in operative time. The CO2 laser fiber did show better outcomes in the areas of blood loss, bipolar cautery use, and intraoperative margins needed.

Titanium dioxide thin films deposited by pulsed laser deposition and integration in radio frequency devices: Study of structure, optical and dielectric properties

NASA Astrophysics Data System (ADS)

Orlianges, Jean-Christophe; Crunteanu, Aurelian; Pothier, Arnaud; Merle-Mejean, Therese; Blondy, Pierre; Champeaux, Corinne

2012-12-01

Titanium dioxide presents a wide range of technological application possibilities due to its dielectric, electrochemical, photocatalytic and optical properties. The three TiO2 allotropic forms: anatase, rutile and brookite are also interesting, since they exhibit different properties, stabilities and growth modes. For instance, rutile has a high dielectric permittivity, of particular interest for the integration as dielectric in components such as microelectromechanical systems (MEMS) for radio frequency (RF) devices. In this study, titanium dioxide thin films are deposited by pulsed laser deposition. Characterizations by Raman spectroscopy and X-ray diffraction show the evolution of the structural properties. Thin films optical properties are investigated using spectroscopic ellipsometry and transmission measurements from UV to IR range. Co-planar waveguide (CPW) devices are fabricated based on these films. Their performances are measured in the RF domain and compared to simulation, leading to relative permittivity values in the range 30-120, showing the potentialities of the deposited material for capacitive switches applications.

Carbon dioxide laser polishing of fused silica surfaces for increased laser-damage resistance at 1064 nm.

PubMed

Temple, P A; Lowdermilk, W H; Milam, D

1982-09-15

Mechanically polished fused silica surfaces were heated with continuous-wave CO(2) laser radiation. Laser-damage thresholds of the surfaces were measured with 1064-nm 9-nsec pulses focused to small spots and with large-spot, 1064-nm, 1-nsec irradiation. A sharp transition from laser-damage-prone to highly laser-damage-resistant took place over a small range in CO(2) laser power. The transition to high damage resistance occurred at a silica surface temperature where material softening began to take place as evidenced by the onset of residual strain in the CO(2) laser-processed part. The small-spot damage measurements show that some CO(2) laser-treated surfaces have a local damage threshold as high as the bulk damage threshold of SiO(2). On some CO(2) laser-treated surfaces, large-spot damage thresholds were increased by a factor of 3-4 over thresholds of the original mechanically polished surface. These treated parts show no obvious change in surface appearance as seen in bright-field, Nomarski, or total internal reflection microscopy. They also show little change in transmissive figure. Further, antireflection films deposited on CO(2) laser-treated surfaces have thresholds greater than the thresholds of antireflection films on mechanically polished surfaces.

[Effect of CO2 laser on prostheses used in middle ear surgery].

PubMed

Szymański, Marcin

2005-01-01

The use of CO2 laser is advocated in primary and revision stapes surgery. The aim of the study was to assess the effect of CO2 laser on stapes prostheses. CO2 laser was applied on several types of stapes prostheses and PORPs, with power settings suggested by the manufacturer (continuous wave, 2 W and 6 W; 0,05 s). Application of the laser on stainless steel or titanium prosthesis did not exert any effect on the structure of the prosthesis. The use of the laser on the Teflon piston caused superficial burning with power 2 W, and melting and holes in the piston with power settings at 6W. Similar plastipore prostheses were melting. Hydroxyapatite PORP shattered after application of the laser energy. Teflon and hydroxyapatite prostheses are easily damaged by the laser energy, therefore applying a laser on them should be avoided. CO2 laser can be used on stainless steel and titanium prostheses without risk of damaging them. However the possibility of transmission of heat to the vestibule has to be taken into consideration.

Use of high-power diode lasers for hardening and thermal conduction welding of metals

NASA Astrophysics Data System (ADS)

Klocke, Fritz; Demmer, Axel; Zaboklicki, A.

1997-08-01

CO2 and Nd:YAG high power lasers have become established as machining tools in industrial manufacturing over the last few years. The most important advantages compared to conventional processing techniques lie in the absence of forces introduced by the laser into the workpiece and in the simple arid highly accurate control in terms ofpositioning and timing making the laser a universally applicable, wear-free and extremely flexible tool /1,2/. The laser can be utilised costeffectively in numerous manufacturing processes but there are also further applications for the laser which produce excellent results from a technical point of view, but are not justified in terms of cost. The extensive use of lasers, particularly in small companies and workshops, is hindered by two main reasons: the complexity and size ofthe laser source and plant and the high investment costs /3/. A new generation of lasers, the high power diode lasers (HDL), combines high performance with a compact design, making the laser a cheap and easy to use tool with many applications /3,4,5,6/. In the diode laser, the laser beam is generated by a microelectronic diode which transforms electrical energy directly into laser energy. Diode lasers with low power outputs have, for some time, been making their mark in our everyday lives: they are used in CD players, laser printers and scanners at cash tills. Modern telecommunications would be impossible without these lasers which enable information to be transmitted in the form oflight impulses through optical fibres. They can also be found in compact precision measurement instrumentation - range fmders, interferometers and pollutant analysis devices /3,6/. In the field of material processing, the first applications ofthe laser, such as for soldering, inscribing, surface hardening and plastic or heat conduction welding, will exceed the limits ofthe relatively low performance output currently available. The diode laser has a shorter wavelength than the CO2 and Nd:YAG lasers making it more favourable in terms ofthe absorption behaviour ofthe laser beam - an advantage that will soon have a significant effect on the range of its applications.

Eruptive keratoacanthomas following carbon dioxide laser resurfacing.

PubMed

Gewirtzman, A; Meirson, D H; Rabinovitz, H

1999-08-01

Skin resurfacing with the carbon dioxide (CO2) laser is currently a popular means of improving rhytides and scars. Scarring, hyperpigmentation, hypopigmentation, and infection are among the complications that have been known to occur in some patients treated with the CO2 laser. We wish to communicate a previously unreported complication of CO2 laser resurfacing-multiple eruptive keratoacanthomas. We describe a 61-year-old woman who presented with multiple eruptive keratoacanthomas subsequent to CO2 laser resurfacing. Her lesions were cultured for fungus and bacteria. Biopsy specimens of two lesions were taken. Cultures were negative for pathogens. Biopsy specimens revealed atypical squamous epithelial proliferation and changes consistent with eruptive keratoacanthomas. Multiple eruptive keratoacanthomas should be considered as a rare complication of CO2 laser resurfacing.

Far-infrared-light shadowgraphy for high extraction efficiency of extreme ultraviolet light from a CO2-laser-generated tin plasma

NASA Astrophysics Data System (ADS)

Matsukuma, Hiraku; Hosoda, Tatsuya; Suzuki, Yosuke; Yogo, Akifumi; Yanagida, Tatsuya; Kodama, Takeshi; Nishimura, Hiroaki

2016-08-01

The two-color, double-pulse method is an efficient scheme to generate extreme ultraviolet light for fabricating the next generation semiconductor microchips. In this method, a Nd:YAG laser pulse is used to expand a several-tens-of-micrometers-scale tin droplet, and a CO2 laser pulse is subsequently directed at the expanded tin vapor after an appropriate delay time. We propose the use of shadowgraphy with a CO2 laser probe-pulse scheme to optimize the CO2 main-drive laser. The distribution of absorption coefficients is derived from the experiment, and the results are converted to a practical absorption rate for the CO2 main-drive laser.

A nonrandomized comparison of the thulium laser and the CO2 laser in primary stapedotomy for otosclerosis.

PubMed

Kamalski, Digna M A; Vincent, Robert; Wegner, Inge; Bittermann, Arnold J N; Grolman, Wilko

2014-12-01

Comparing hearing results in patients with otosclerosis treated with laser-assisted stapedotomy using the 2-μm thulium laser or the CO2 laser. Prospective nonrandomized clinical study. In a tertiary referral center in France (Jean Causse Ear Clinic, Béziers), 208 primary stapedotomies were performed in 204 patients between March 2008 and November 2009. Sufficient follow-up data were available for 194 procedures. The fenestration in the footplate was made with the thulium laser in 98 procedures and with a flexible CO2 laser in 96 procedures. Preoperative and postoperative audiometric results were compared. Side effects, such as vertigo and tinnitus, were scored. Patients treated with the CO2 laser had better hearing outcome compared with those treated with the thulium laser at both 3 and 12 months of follow-up. At 3 months, the success of the surgery, defined as closure of the air-bone gap to within 10 dB, was 90.0% in the thulium group compared with 96.8% in the CO2 group. Bone conduction shift showed an overall deterioration of 1.6 dB (standard deviation, 6.9 dB) in the thulium group compared with an improvement of 1.3 dB (standard deviation, 4 dB) in the CO2 group. In the thulium group, there were four patients with sensorineural hearing loss (4.4%) and three with tinnitus (3.1%) compared with none in the CO2 group. Stapedotomy surgery performed with a fiber-delivered thulium laser resulted in a higher chance of inner ear damage measured by bone conduction shift compared with the use of a fiber-delivered CO2 laser. We advise not to use the thulium laser for stapedotomy.

Potential of CO2 lasers (10.6 µm) associated with fluorides in inhibiting human enamel erosion.

PubMed

Ramos-Oliveira, Thayanne Monteiro; Ramos, Thaysa Monteiro; Esteves-Oliveira, Marcela; Apel, Christian; Fischer, Horst; Eduardo, Carlos de Paula; Steagall, Washington; Freitas, Patricia Moreira de

2014-01-01

This in vitro study aimed to investigate the potential of CO2 lasers associated with different fluoride agents in inhibiting enamel erosion. Human enamel samples were randomly divided into 9 groups (n = 12): G1-eroded enamel; G2-APF gel; G3-AmF/NaF gel; G4-AmF/SnF2 solution; G5-CO2 laser (λ = 10.6 µm)+APF gel; G6-CO2 laser+AmF/NaF gel; G7-CO2laser+AmF/SnF2solution; G8-CO2 laser; and G9-sound enamel. The CO2 laser parameters were: 0.45 J/cm2; 6 μs; and 128 Hz. After surface treatment, the samples (except from G9) were immersed in 1% citric acid (pH 4.0, 3 min). Surface microhardness was measured at baseline and after surface softening. The data were statistically analyzed by one-way ANOVA and Tukey's tests (p < 0.05). G2 (407.6 ± 37.3) presented the highest mean SMH after softening, followed by G3 (407.5 ± 29.8) and G5 (399.7 ± 32.9). Within the fluoride-treated groups, G4 (309.0 ± 24.4) had a significantly lower mean SMH than G3 and G2, which were statistically similar to each other. AmF/NaF and APF application showed potential to protect and control erosion progression in dental enamel, and CO2 laser irradiation at 0.45J/cm2 did not influence its efficacy. CO2 laser irradiation alone under the same conditions could also significantly decrease enamel erosive mineral loss, although at lower levels.

Multilayered Microelectronic Device Package With An Integral Window

DOEpatents

Peterson, Kenneth A.; Watson, Robert D.

2004-10-26

A microelectronic package with an integral window mounted in a recessed lip for housing a microelectronic device. The device can be a semiconductor chip, a CCD chip, a CMOS chip, a VCSEL chip, a laser diode, a MEMS device, or a IMEMS device. The package can be formed of a low temperature co-fired ceramic (LTCC) or high temperature cofired ceramic (HTCC) multilayered material, with the integral window being simultaneously joined (e.g. co-fired) to the package body during LTCC or HTCC processing. The microelectronic device can be flip-chip bonded and oriented so that a light-sensitive side is optically accessible through the window. The result is a compact, low profile package, having an integral window mounted in a recessed lip, that can be hermetically sealed.

Rate constants of quenching and vibrational relaxation in the OH({{A}^{2}}{{ \\Sigma }^{+}},v=0,1 ), manifold with various colliders

NASA Astrophysics Data System (ADS)

Martini, L. M.; Gatti, N.; Dilecce, G.; Scotoni, M.; Tosi, P.

2017-03-01

Laser induced fluorescence is intensively used for the detection of OH in many atmospheric pressure discharge devices. At this pressure, a quantitative knowledge of the collision phenomena in the upper excited state is critical. Here we report the measurement at T  =  300 K of a set of rate constants of electronic quenching and vibrational relaxation of the OH≤ft({{A}2}{{ Σ }+},{{v}\\prime}=0,1\\right) electronic state, by collision with N2, O2, H2O, CO2, CO, H2, D2, CH4, C2H2, C2H4, C2H6. These are the main gases in applications like plasma medicine, hydrocarbons reforming and CO2 conversion. Available literature data are revisited, and new data are added, mostly relevant to {{v}\\prime}=1 quenching and vibrational relaxation.

New ZrO2/Al2O3 Nanocomposite Fabricated from Hybrid Nanoparticles Prepared by CO2 Laser Co-Vaporization

PubMed Central

Bartolomé, José F.; Smirnov, Anton; Kurland, Heinz-Dieter; Grabow, Janet; Müller, Frank A.

2016-01-01

Alumina toughened zirconia (ATZ) and zirconia toughened alumina (ZTA) are currently the materials of choice to meet the need for tough, strong, and bioinert ceramics for medical devices. However, the mechanical properties of ZrO2/Al2O3 dispersion ceramics could be considerably increased by reducing the corresponding grain sizes and by improving the homogeneity of the phase dispersion. Here, we prepare nanoparticles with an intraparticular phase distribution of Zr(1−x)AlxO(2−x/2) and (γ-, δ-)Al2O3 by the simultaneous gas phase condensation of laser co-vaporized zirconia and alumina raw powders. During subsequent spark plasma sintering the zirconia defect structures and transition alumina phases transform to a homogeneously distributed dispersion of tetragonal ZrO2 (52.4 vol%) and α-Al2O3 (47.6 vol%). Ceramics sintered by spark plasma sintering are completely dense with average grain sizes in the range around 250 nm. Outstanding mechanical properties (flexural strength σf = 1500 MPa, fracture toughness KIc = 6.8 MPa m1/2) together with a high resistance against low temperature degradation make these materials promising candidates for next generation bioceramics in total hip replacements and for dental implants. PMID:26846310

New ZrO2/Al2O3 Nanocomposite Fabricated from Hybrid Nanoparticles Prepared by CO2 Laser Co-Vaporization

NASA Astrophysics Data System (ADS)

Bartolomé, José F.; Smirnov, Anton; Kurland, Heinz-Dieter; Grabow, Janet; Müller, Frank A.

2016-02-01

Alumina toughened zirconia (ATZ) and zirconia toughened alumina (ZTA) are currently the materials of choice to meet the need for tough, strong, and bioinert ceramics for medical devices. However, the mechanical properties of ZrO2/Al2O3 dispersion ceramics could be considerably increased by reducing the corresponding grain sizes and by improving the homogeneity of the phase dispersion. Here, we prepare nanoparticles with an intraparticular phase distribution of Zr(1-x)AlxO(2-x/2) and (γ-, δ-)Al2O3 by the simultaneous gas phase condensation of laser co-vaporized zirconia and alumina raw powders. During subsequent spark plasma sintering the zirconia defect structures and transition alumina phases transform to a homogeneously distributed dispersion of tetragonal ZrO2 (52.4 vol%) and α-Al2O3 (47.6 vol%). Ceramics sintered by spark plasma sintering are completely dense with average grain sizes in the range around 250 nm. Outstanding mechanical properties (flexural strength σf = 1500 MPa, fracture toughness KIc = 6.8 MPa m1/2) together with a high resistance against low temperature degradation make these materials promising candidates for next generation bioceramics in total hip replacements and for dental implants.

[Experimental study of brain lesions after combined coaxial exposure to high-peaked pulse wave form CO2 and Nd: YAG lasers on the brain].

PubMed

Tsuyumu, M; Verasques, G; Yamazaki, S; Kuroiwa, T; Suzuki, R; Takei, H; Suzuki, K; Inaba, Y

1985-04-01

The CO2 laser is useful for cutting and vaporization but not for coagulation and hemostasis. On the contrary, YAG laser is effective for coagulation and hemostasis but not for cutting. The purpose of this study is to examine the effect of the exposure of combined, coaxial CO2 and YAG laser on the animal brain to supplement the advantages and draw-backs of each other. To compare these results, each of non-combined pulse wave form CO2 and YAG lasers was employed separately. The lasers in this study were pulse wave form CO2 and YAG lasers, employed separately or simultaneously using 130 YZ of Nihon Infrared Industries Company. Japanese white rabbits were anesthetized with pentobarbital. Fronto-parietal burr holes were made, the dura was removed and then Evans blue solution was injected intravenously. The lasers were employed to the cerebral cortex without great vessels using a micromanipulator attached to the operative microscope with a distance of 30 cm. The spot size was 700 mu for CO2 laser and 1200 mu for YAG laser. The first experiment was to see the effect of nine combinations of simultaneous coaxial CO2 of 2, 4 and 8 watts and YAG lasers of 10, 20 and 40 watts, 1 sec on the brain. In the second experiment, also combining two lasers, the exposure time of YAG laser was elongated from 1 or 2 seconds into 2 or 4 seconds and the arrangement of powers was the same as that of the first experiment. The lesions were thus made in 18 different conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

A blackbody-pumped CO2-N2 transfer laser

NASA Astrophysics Data System (ADS)

Deyoung, R. J.; Higdon, N. S.

1984-08-01

A compact blackbody-pumped CO2-N2 transfer laser was constructed and the significant operating parameters were investigated. Lasing was achieved at 10.6 microns by passing preheated N2 through a 1.5-mm-diameter nozzle to a laser cavity where the N2 was mixed with CO2 and He. An intrinsic efficiency of 0.7 percent was achieved for an oven temperature of 1473 K and N2 oven pressure of 440 torr. The optimum laser cavity consisted of a back mirror with maximum reflectivity and an output mirror with 97.5-percent reflectivity. The optimum gas mixture was 1CO2/.5He/6N2. The variation of laser output was measured as a function of oven temperature, nozzle diameter, N2 oven pressure, He and CO2 partial pressures, nozzle-to-oven separation, laser cell temperature, and output laser mirror reflectivity. With these parameters optimized, outputs approaching 1.4 watts were achieved.

A blackbody-pumped CO2-N2 transfer laser

NASA Technical Reports Server (NTRS)

Deyoung, R. J.; Higdon, N. S.

1984-01-01

A compact blackbody-pumped CO2-N2 transfer laser was constructed and the significant operating parameters were investigated. Lasing was achieved at 10.6 microns by passing preheated N2 through a 1.5-mm-diameter nozzle to a laser cavity where the N2 was mixed with CO2 and He. An intrinsic efficiency of 0.7 percent was achieved for an oven temperature of 1473 K and N2 oven pressure of 440 torr. The optimum laser cavity consisted of a back mirror with maximum reflectivity and an output mirror with 97.5-percent reflectivity. The optimum gas mixture was 1CO2/.5He/6N2. The variation of laser output was measured as a function of oven temperature, nozzle diameter, N2 oven pressure, He and CO2 partial pressures, nozzle-to-oven separation, laser cell temperature, and output laser mirror reflectivity. With these parameters optimized, outputs approaching 1.4 watts were achieved.

Healing of rat mouth mucosa after irradiation with CO2, Nd:YAG, and CO2-Nd:YAG combination lasers.

PubMed

Luomanen, M; Rauhamaa-Mäkinen, R; Meurman, J H; Kosloff, T; Tiitta, O

1994-08-01

The healing process of wounds made by a combination laser was studied in 90 rats. The laser system enabled both separate and combined use of CO2 and Nd:YAG laser irradiations. The laser wounds and the control excision wounds made by alligator forceps appeared on both sides of the tongue. Specimens from the wound sites were taken immediately, 6 h, and 1, 2, 4, 7, 11, 21, 28, and 42 days after surgery. The wound-healing process was studied by macroscopic evaluation before preparing the specimens for light microscopy. Some differences were noted in the wound-healing process among the three groups into which the experimental animals were divided. Tissue coagulation damage was most extensive in the Nd:YAG laser sites, where it was observed in its full extent 4 days after surgery. Epithelial cells were seen to begin to proliferate in all the wounds 6 h after surgery. Re-epithelialization was completed by between 7 (CO2) and 21 days (Nd:YAG) at all the wound sites. The inflammatory cell infiltration was more prominent in the Nd:YAG and the CO2-Nd:YAG combination laser wounds than in the CO2 and excision wounds during healing. Tissue regeneration occurred faster with less contraction in the combination CO2-Nd:YAG wounds than in Nd:YAG wounds. The best macroscopic healing result was seen in the CO2 wound sites. The combination laser was effective both at cutting and at coagulating tissue. Combining the CO2 and Nd:YAG laser irradiation into one beam resulted in a greater incision depth than what could have been expected from using the two lasers separately.

Selective material ablation by the TEA CO2 laser

NASA Astrophysics Data System (ADS)

Sumiyoshi, Tetsumi; Shiratori, Akira; Ninomiya, Yutaka; Obara, Minoru

1995-03-01

This paper reports two topics in the material processing using TEA CO2 lasers. We demonstrated selective ablation of hydrogenated amorphous silicon (a-Si:H) thin layer on a quartz substrate by the second harmonic (SH) radiation of TEA CO2 laser generated by AgGaSe2 nonlinear crystal. Si-H bonds contained in a-Si:H strongly absorb the 5 micrometers SH radiation and resulted in the selective ablation of the a-Si:H layer. The successful ablation processing of ethylenetetrafluoroethylene (ETFE) copolymer by the 9.6 micrometers fundamental wavelength TEA CO2 laser is also reported. Only ETFE thin film adhered to an aluminum substrate can be ablated by the TEA CO2 laser.

Lasers in endodontics: an overview

NASA Astrophysics Data System (ADS)

Frentzen, Matthias; Braun, Andreas; Koort, Hans J.

2002-06-01

The interest in endodontic use of dental laser systems is increasing. Developing laser technology and a better understanding of laser effects widened the spectrum of possible endodontic indications. Various laser systems including excimer-, argon+-, diode-, Nd:YAG-, Er:YAG- and CO2-lasers are used in pulp diagnosis, treatment of hypersensitivity, pulp capping, sterilization of root canals, root canal shaping and obturation or apicoectomy. With the development of new delivery systems - thin and flexible fibers - for many different wavelengths laser applications in endodontics may increase. Since laser devices are still relatively costly, access to them is limited. Most of the clinical applications are laser assisted procedures such as the removing of pulp remnants and debris or disinfection of infected root canals. The essential question is whether a laser can provide improved treatment over conventional care. To perform laser therapy in endodontics today different laser types with adopted wavelengths and pulse widths are needed, each specific to a particular application. Looking into the future we will need endodontic laser equipment providing optimal laser parameters for different treatment modalities. Nevertheless, the quantity of research reports from the last decade promises a genuine future for lasers in endodontics.

REVIEWS OF TOPICAL PROBLEMS: Gas lasers with solar excitation

NASA Astrophysics Data System (ADS)

Gordiets, B. F.; Panchenko, Vladislav Ya

1986-07-01

CONTENTS 1. Introduction 703 2. General requirements for laser media using solar excitation 704 3. Lasers with direct excitation by solar light 705 3.1. Basic characteristics of laser media. 3.2. Photodissociation Br2-CO2 lasers. 3.3. Interhalogen molecule lasers. 3.4. Iodine lasers. 3.5. Alkali metal vapor lasers. 4. Lasers with thermal conversion of solar pumping 709 4.1. General considerations. 4.2. CO2 laser with excitation in a black body cavity and with gas flow. 4.3. cw CO2 laser without gas flow. 5. Space laser media with solar excitation 713 5.1. Population inversion of molecular levels in the outer atmosphere of the Earth. 5.2. Laser effect in the atmospheres of Venus and Mars. 5.3. Terrestrial experimental technique for observing infrared emission in the atmospheres of planets. 5.4. Designs for laser systems in the atmospheres of Venus and Mars. 6. Conclusions 717 References 717

Comparison of Ultrasonic and CO2 Laser Pretreatment Methods on Enzyme Digestibility of Corn Stover

PubMed Central

Tian, Shuang-Qi; Wang, Zhen-Yu; Fan, Zi-Luan; Zuo, Li-Li

2012-01-01

To decrease the cost of bioethanol production, biomass recalcitrance needs to be overcome so that the conversion of biomass to bioethanol becomes more efficient. CO2 laser irradiation can disrupt the lignocellulosic physical structure and reduce the average size of fiber. Analyses with Fourier transform infrared spectroscopy, specific surface area, and the microstructure of corn stover were used to elucidate the enhancement mechanism of the pretreatment process by CO2 laser irradiation. The present work demonstrated that the CO2 laser had potential to enhance the bioconversion efficiency of lignocellulosic waste to renewable bioethanol. The saccharification rate of the CO2 laser pretreatment was significantly higher than ultrasonic pretreatment, and reached 27.75% which was 1.34-fold of that of ultrasonic pretreatment. The results showed the impact of CO2 laser pretreatment on corn stover to be more effective than ultrasonic pretreatment. PMID:22605970

Monitoring of catalyst performance in CO2 lasers using frequency modulation spectroscopy with diode lasers

NASA Technical Reports Server (NTRS)

Wang, Liang-Guo; Sachse, Glen

1990-01-01

Closed-cycle CO2 laser operation with removal of O2 and regeneration of CO2 can be achieved by catalytic CO-O2 recombination. Both parametric studies of the optimum catalyst formulation and long-term performance tests require on line monitoring of CO, O2 and CO2 concentrations. There are several existing methods for molecular oxygen detection. These methods are either intrusive (such as electrochemical method or mass spectrometry) or very expensive (such as CARS, UV laser absorption). Researchers demonstrated a high-sensitivity spectroscopic measurement of O2 using the two-tone frequency modulation spectroscopy (FMS) technique with a near infrared GaAlAs diode laser. Besides its inexpensive cost, fast response time, nonintrusive measurements and high sensitivity, this technique may also be used to differentiate between isotopes due to its high spectroscopic resolution. This frequency modulation spectroscopy technique could also be applied for the on-line monitoring of CO and CO2 using InGaAsP diode lasers operation in the 1.55 microns region and H2O in the 1.3 microns region. The existence of single mode optical fibers at the near infrared region makes it possible to combine FMS with optical fiber technology. Optical fiber FMS is particularly suitable for making point-measurements at one or more locations in the CO2 laser/catalyst system.

LaRC-developed catalysts for CO2 lasers

NASA Technical Reports Server (NTRS)

Upchurch, Billy T.; Kielin, Erik J.; Miller, Irvin M.

1990-01-01

Pulsed CO2 lasers have many remote sensing applications from space, airborne, and ground platforms. The NASA Laser Atmospheric Wind Sounder (LAWS) system will be designed to measure wind velocities from polar earth orbit for a period of up to three years. Accordingly, this and other applications require a closed-cycle pulsed CO2 laser which necessitates the use of an efficient CO-O2 recombination catalyst for these dissociation products which otherwise would degrade the laser operation. The required catalyst must not only operate at low temperatures but also must operate efficiently for long time periods. The research effort at NASA LaRC has centered around development and testing of CO oxidation catalysts for closed-cycle, pulsed, common and rare-isotope CO2 lasers. Researchers examined available commercial catalysts both in a laser and under simulated closed-cycle laser conditions with efforts aimed toward a thorough understanding of the fundamental catalytic reaction. These data were used to design and synthesize new catalyst compositions to better meet the catalyst requirements for closed-cycle pulsed CO2 lasers. Syntheses and test results for catalysts developed at Langley Research Center which have significantly better long-term decay characteristics than previously available catalysts and at the same time operate quite well under lower temperature conditions are discussed.

Flow Visualization of Density in a Cryogenic Wind Tunnel Using Planar Rayleigh and Raman Scattering

NASA Technical Reports Server (NTRS)

Herring, Gregory C.; Shirinzadeh, Behrooz

2002-01-01

Using a pulsed Nd:YAG laser (532 nm) and a gated, intensified charge-coupled device, planar Rayleigh and Raman scattering techniques have been used to visualize the unseeded Mach 0.2 flow density in a 0.3-meter transonic cryogenic wind tunnel. Detection limits are determined for density measurements by using both unseeded Rayleigh and Raman (N2 vibrational) methods. Seeding with CO2 improved the Rayleigh flow visualization at temperatures below 150 K. The seeded Rayleigh version was used to demonstrate the observation of transient flow features in a separated boundary layer region, which was excited with an oscillatory jet. Finally, a significant degradation of the laser light sheet, in this cryogenic facility, is discussed.

Electric field-induced resistive switching, magnetism, and photoresponse modulation in a Pt/Co0.03Zn0.97O/Nb:SrTiO3 multi-function heterostructure

NASA Astrophysics Data System (ADS)

Luo, Zhipeng; Pei, Ling; Li, Meiya; Zhu, Yongdan; Xie, Shuai; Cheng, Xiangyang; Liu, Jiaxian; Ding, Huaqi; Xiong, Rui

2018-04-01

A Co0.03Zn0.97O (CZO) thin film was epitaxially grown on a Nb doped (001) SrTiO3 (NSTO) single-crystal substrate by pulsed laser deposition to form a Pt/CZO/NSTO heterostructure. This device exhibits stable bipolar resistive switching, well retention and endurance, multilevel memories, and a resistance ratio of high resistance state (HRS)/low resistance state (LRS) up to 7 × 105. Under the illumination of a 405 nm laser, the HRS of the device showed distinct photoelectricity with an open-circuit voltage of 0.5 V. A stronger ferromagnetism was observed at the HRS than at the LRS. The above phenomenon is attributable to the accumulation and migration of oxygen vacancies at the interface of CZO/NSTO. Our results demonstrated a pathway towards making multifunctional devices that simultaneously exhibit resistive switching, photoelectricity, and ferromagnetism.

Integration of Organic Electrochemical and Field-Effect Transistors for Ultraflexible, High Temporal Resolution Electrophysiology Arrays.

PubMed

Lee, Wonryung; Kim, Dongmin; Rivnay, Jonathan; Matsuhisa, Naoji; Lonjaret, Thomas; Yokota, Tomoyuki; Yawo, Hiromu; Sekino, Masaki; Malliaras, George G; Someya, Takao

2016-11-01

Integration of organic electrochemical transistors and organic field-effect transistors is successfully realized on a 600 nm thick parylene film toward an electrophysiology array. A single cell of an integrated device and a 2 × 2 electrophysiology array succeed in detecting electromyogram with local stimulation of the motor nerve bundle of a transgenic rat by a laser pulse. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Extinction of CO2 Laser Radiation Under Adverse Weather Conditions

DTIC Science & Technology

1982-06-01

System Design 60 a, Gaussian Optics 60 b, Laser Transmissometer 61 4. Measurement Errors 68 VI DISCUSSION OF RESULTS 69 1, Introduction...water soluble aerosols (a 1 106 AFWAL-TR-81 -.1280 TABLE 17 EXTINCTION OF CO2 LASER LINES FOR A CONSTANI RAIN RATE OF 1.82 mm/HR, 22 APRIL, 1935 HOURS...number) Laser Propagation Rain Laser Extinction CO2 Lasers Adverse Weather Aerosol s - 20 RACT (Continue on reverse side If necessary

Recent developments in CO2 lasers

NASA Astrophysics Data System (ADS)

Du, Keming

1993-05-01

CO2 lasers have been used in industry mainly for such things as cutting, welding, and surface processing. To conduct a broad spectrum of high-speed and high-quality applications, most of the developments in industrial CO2 lasers at the ILT are aimed at increasing the output power, optimizing the beam quality, and reducing the production costs. Most of the commercial CO2 lasers above 5 kW are transverse-flow systems using dc excitation. The applications of these lasers are limited due to the lower beam quality, the poor point stability, and the lower modulation frequency. To overcome the problems we developed a fast axial- flow CO2 laser using rf excitation with an output of 13 kW. In section 2 some of the results are discussed concerning the gas flow, the discharge, the resonator design, optical effects of active medium, the aerodynamic window, and the modulation of the output power. The first CO2 lasers ever built are diffusion-cooled systems with conventional dc excited cylindrical discharge tubes surrounded by cooling jackets. The output power per unit length is limited to 50 W/m by those lasers with cylindrical tubes. In the past few years considerable increases in the output power were achieved, using new mechanical geometries, excitation- techniques, and resonator designs. This progress in diffusion-cooled CO2 lasers is presented in section 3.

High repetition rate sealed CO2 TEA lasers using heterogeneous catalysts

NASA Astrophysics Data System (ADS)

Price, H. T.; Shaw, S. R.

1987-04-01

The significant operational advantages offered by CO2 lasers, operating in the 10.6 micron region of the spectrum, over current solid state lasers, emitting in the near IR region, have prompted increased interest in the development of compact, reliable, rugged CO2 laser sources. Perhaps the most critical aspect associated with achieving a laser compatible with military use is the development of lasers which require no gas replenishment. Sealed, single shot, CO2 TEA lasers have been available for a number of years. Stark et al were first to demonstrate reliable sealed operation in single shot CO2 TEA lasers in 1975 using gas catalysis. GEC Avionics reported the compact, environmentally qualified, MKIII CO2 TEA laser with a pulse life of greater than 10 to the 6th power pulses in 1980. A sealed laser lifetime of greater than 10 to the 6th power pulses is acceptable for single shot cases, such as direct detection rangefinders for tank laser sights. However, in many other applications, such as tracking of fast moving targets, it is essential that a repetition rate of typically 30Hz to 100Hz is employed. In such cases, a pulse lifetime of 10 to the 6th power pulses is no longer sufficient and a minimum pulse lifetime 10 to the 7th power pulses is essential to ensure a useful service life. In 1983 Stark el al described a sealed, 100Hz CO2 TEA laser, with a life of greater than 2.6 x 10 to the 6th power, which employed heterogeneous catalysis. Following this pioneering work, GEC Avionics has been engaged in the development of sealed high repetition rate lasers with a pulse lifetime of 20 million pulses.

High repetition rate sealed CO2 TEA lasers using heterogeneous catalysts

NASA Technical Reports Server (NTRS)

Price, H. T.; Shaw, S. R.

1987-01-01

The significant operational advantages offered by CO2 lasers, operating in the 10.6 micron region of the spectrum, over current solid state lasers, emitting in the near IR region, have prompted increased interest in the development of compact, reliable, rugged CO2 laser sources. Perhaps the most critical aspect associated with achieving a laser compatible with military use is the development of lasers which require no gas replenishment. Sealed, single shot, CO2 TEA lasers have been available for a number of years. Stark et al were first to demonstrate reliable sealed operation in single shot CO2 TEA lasers in 1975 using gas catalysis. GEC Avionics reported the compact, environmentally qualified, MKIII CO2 TEA laser with a pulse life of greater than 10 to the 6th power pulses in 1980. A sealed laser lifetime of greater than 10 to the 6th power pulses is acceptable for single shot cases, such as direct detection rangefinders for tank laser sights. However, in many other applications, such as tracking of fast moving targets, it is essential that a repetition rate of typically 30Hz to 100Hz is employed. In such cases, a pulse lifetime of 10 to the 6th power pulses is no longer sufficient and a minimum pulse lifetime 10 to the 7th power pulses is essential to ensure a useful service life. In 1983 Stark el al described a sealed, 100Hz CO2 TEA laser, with a life of greater than 2.6 x 10 to the 6th power, which employed heterogeneous catalysis. Following this pioneering work, GEC Avionics has been engaged in the development of sealed high repetition rate lasers with a pulse lifetime of 20 million pulses.

Closed cycle electric discharge laser design investigation

NASA Technical Reports Server (NTRS)

Baily, P. K.; Smith, R. C.

1978-01-01

Closed cycle CO2 and CO electric discharge lasers were studied. An analytical investigation assessed scale-up parameters and design features for CO2, closed cycle, continuous wave, unstable resonator, electric discharge lasing systems operating in space and airborne environments. A space based CO system was also examined. The program objectives were the conceptual designs of six CO2 systems and one CO system. Three airborne CO2 designs, with one, five, and ten megawatt outputs, were produced. These designs were based upon five minute run times. Three space based CO2 designs, with the same output levels, were also produced, but based upon one year run times. In addition, a conceptual design for a one megawatt space based CO laser system was also produced. These designs include the flow loop, compressor, and heat exchanger, as well as the laser cavity itself. The designs resulted in a laser loop weight for the space based five megawatt system that is within the space shuttle capacity. For the one megawatt systems, the estimated weight of the entire system including laser loop, solar power generator, and heat radiator is less than the shuttle capacity.

A randomized controlled clinical and histopathological trial comparing excisional biopsies of oral fibrous hyperplasias using CO2 and Er:YAG laser.

PubMed

Suter, Valerie G A; Altermatt, Hans Jörg; Bornstein, Michael M

2017-04-01

This study was conducted in order to compare clinical and histopathological outcomes for excisional biopsies when using pulsed CO 2 laser versus Er:YAG laser. Patients (n = 32) with a fibrous hyperplasia in the buccal mucosa were randomly allocated to the CO 2 (140 Hz, 400 μs, 33 mJ) or the Er:YAG laser (35 Hz, 297 μs, 200 mJ) group. The duration of excision, intraoperative bleeding and methods to stop the bleeding, postoperative pain (VAS; ranging 0-100), the use of analgesics, and the width of the thermal damage zone (μm) were recorded and compared between the two groups. The median duration of the intervention was 209 s, and there was no significant difference between the two methods. Intraoperative bleeding occurred in 100% of the excisions with Er:YAG and 56% with CO 2 laser (p = 0.007). The median thermal damage zone was 74.9 μm for CO 2 and 34.0 μm for Er:YAG laser (p < 0.0001). The median VAS score on the evening after surgery was 5 for the CO 2 laser and 3 for the Er:YAG group. To excise oral soft tissue lesions, CO 2 and Er:YAG lasers are both valuable tools with a short time of intervention and postoperative low pain. More bleeding occurs with the Er:YAG than CO 2 laser, but the lower thermal effect of Er:YAG laser seems advantageous for histopathological evaluation.

Development of high-power CO2 lasers and laser material processing

NASA Astrophysics Data System (ADS)

Nath, Ashish K.; Choudhary, Praveen; Kumar, Manoj; Kaul, R.

2000-02-01

Scaling laws to determine the physical dimensions of the active medium and optical resonator parameters for designing convective cooled CO2 lasers have been established. High power CW CO2 lasers upto 5 kW output power and a high repetition rate TEA CO2 laser of 500 Hz and 500 W average power incorporated with a novel scheme for uniform UV pre- ionization have been developed for material processing applications. Technical viability of laser processing of several engineering components, for example laser surface hardening of fine teeth of files, laser welding of martensitic steel shroud and titanium alloy under-strap of turbine, laser cladding of Ni super-alloy with stellite for refurbishing turbine blades were established using these lasers. Laser alloying of pre-placed SiC coating on different types of aluminum alloy, commercially pure titanium and Ti-6Al-4V alloy, and laser curing of thermosetting powder coating have been also studied. Development of these lasers and results of some of the processing studies are briefly presented here.

Carbon Dioxide Laser Absorption Spectrometer (CO2LAS) Aircraft Measurements of CO2

NASA Technical Reports Server (NTRS)

Christensen, Lance E.; Spiers, Gary D.; Menzies, Robert T.; Jacob, Joseph C.; Hyon, Jason

2011-01-01

The Jet Propulsion Laboratory Carbon Dioxide Laser Absorption Spectrometer (CO2LAS) utilizes Integrated Path Differential Absorption (IPDA) at 2.05 microns to obtain CO2 column mixing ratios weighted heavily in the boundary layer. CO2LAS employs a coherent detection receiver and continuous-wave Th:Ho:YLF laser transmitters with output powers around 100 milliwatts. An offset frequency-locking scheme coupled to an absolute frequency reference enables the frequencies of the online and offline lasers to be held to within 200 kHz of desired values. We describe results from 2009 field campaigns when CO2LAS flew on the Twin Otter. We also describe spectroscopic studies aimed at uncovering potential biases in lidar CO2 retrievals at 2.05 microns.

2-Micron Laser Transmitter for Coherent CO2 DIAL Measurement

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Bai, Yingxin; Yu, Jirong

2009-01-01

Carbon dioxide (CO2) has been recognized as one of the most important greenhouse gases. It is essential for the study of global warming to accurately measure the CO2 concentration in the atmosphere and continuously record its variation. A high repetition rate, highly efficient, Q-switched 2-micron laser system as the transmitter of a coherent differential absorption lidar for CO2 measurement has been developed in NASA Langley Research Center. This laser system is capable of making a vertical profiling of CO2 from ground and column measurement of CO2 from air and space-borne platform. The transmitter is a master-slave laser system. The master laser operates in a single frequency, either on-line or off-line of a selected CO2 absorption line. The slave laser is a Q-switched ring-cavity Ho:YLF laser which is pumped by a Tm:fiber laser. The repetition rate can be adjusted from a few hundred Hz to 10 kHz. The injection seeding success rate is from 99.4% to 99.95%. For 1 kHz operation, the output pulse energy is 5.5mJ with the pulse length of 50 ns. The optical-to-optical efficiency is 39% when the pump power is 14.5W. A Ho:YLF laser operating in the range of 2.05 micrometers can be tuned over several characteristic lines of CO2 absorption. Experimentally, a diode pumped Ho:Tm:YLF laser has been successfully used as the transmitter of coherent differential absorption lidar for the measurement of CO2 with a repetition rate of 5 Hz and pulse energy of 75 mJ. For coherent detection, high repetition rate is required for speckle averaging to obtain highly precise measurements. However, a diode pumped Ho:Tm:YLF laser can not operate in high repetition rate due to the large heat loading and up-conversion. A Tm:fiber laser pumped Ho:YLF laser with low heat loading can operate in high repetition rate. A theoretical model has been established to simulate the performance of Tm:fiber laser pumped Ho:YLF lasers. For continuous wave (CW) operation, high pump intensity with small beam size is suitable for high efficiency. For Q-switched operation, the optimal energy extraction relies on the pump intensity, pump volume, and pump duration which is inversely proportion to the repetition rate. CW and Q-switched Ho:YLF lasers with different linear cavity configurations have been designed and demonstrated for a 30 W Tm:fiber pump laser. The CW Ho laser slope efficiency and optical-to-optical efficiencies reach 65% and 55%, respectively. The pulsed laser efficiency depends on the repetition rate. For 1 kHz operation, the optical-to-optical efficiency is 39% when the pump power is 14.5W. Currently, the injection seeding success rate is between 99.4% and 99.95%. After a ten thousand pulses, the standard deviation of the laser frequency jitter is about 3 MHz. It meets the requirements of highly precise CO2 concentration measurement. In conclusion, an injection seeded, high repetition rate, Q-switched Ho:YLF laser has been developed for a coherent CO2 differential absorption lidar. This master-slave laser system has high optical-to-optical efficiency and seeding success rate. It can potentially meet the requirements of the coherent detection of CO2 concentration by a differential absorption lidar technique.

Development of a gas cell-based laser ion source for RIKEN PALIS

NASA Astrophysics Data System (ADS)

Sonoda, T.; Wada, M.; Tomita, H.; Sakamoto, C.; Takatsuka, T.; Noto, T.; Iimura, H.; Matsuo, Y.; Kubo, T.; Shinozuka, T.; Wakui, T.; Mita, H.; Naimi, S.; Furukawa, T.; Itou, Y.; Schury, P.; Miyatake, H.; Jeong, S.; Ishiyama, H.; Watanabe, Y.; Hirayama, Y.

2013-04-01

We developed a prototype laser ionization gas cell with a beam extraction system. This device is for use of PArasitic Laser Ion-Source (PALIS), which will be implemented into RIKEN's fragment separator, BigRIPS as a part of SLOWRI. Off-line resonant laser ionization for stable Co, Cu, Fe, Ni, Ti, Nb, Sn, In and Pd inside the gas cell, ion extraction and transport to the high-vacuum region via SPIG and QMS have been confirmed (Sonoda et al, Nucl Instrum Meth B 295:1, 2013).

A comparative evaluation: Oral leukoplakia surgical management using diode laser, CO2 laser, and cryosurgery.

PubMed

Natekar, Madhukar; Raghuveer, Hosahallli-Puttaiah; Rayapati, Dilip-Kumar; Shobha, Eshwara-Singh; Prashanth, Nagesh-Tavane; Rangan, Vinod; Panicker, Archana G

2017-06-01

The comparatively evaluate the three surgical treatment modalities namely cryosurgery, diode and CO2 laser surgery in terms of healing outcomes on the day of surgery, first and second week post operatively and recurrence at the end of 18 months was assessed. Thirty selected patients were divided randomly into three groups. Each group comprising of ten patients were subjected to one of the three modalities of treatment namely cryosurgery, diode laser or CO2 laser surgery for ablation of OL. Obtained data was analyzed using mainly using Chi-square and Anova tests. Study showed statistical significant differences (p > 0.05) for evaluation parameters like pain, edema and scar. The parameters like infection, recurrence, bleeding showed no statistical significance. Pain was significantly higher in CO2 laser surgery group as compared with diode laser group. There was no recurrence observed at the end of the 6 months follow up period in all the three study groups. Observations from the study highlights that all three surgical modalities used in this study were effective for treatment of OL, and the overall summation of the results of the study showed that laser therapy (CO2 and Diode) seems to offer better clinically significant results than cryotherapy. Key words: Oral premalignant lesion, leukoplakia, cryosurgery, CO2 laser surgery, diode laser surgery.

CO2 laser treatment for regional cutaneous malignant melanoma metastases.

PubMed

van Jarwaarde, Jorien A; Wessels, Ronnie; Nieweg, Omgo E; Wouters, Michel W J M; van der Hage, Jos A

2015-01-01

Cutaneous in-transit and satellite metastases are distressing presentations of melanoma progression. The purpose of this study was to analyze the efficacy of carbon dioxide (CO2) lasers in patients with melanoma with cutaneous in-transit and satellite metastases. Results of CO2 laser therapy were retrospectively evaluated in 22 patients between January 2004 and January 2008. The number of laser treatments, postoperative morbidity, regional control, and overall survival were analyzed. Twenty-two patients received a total of 42 CO2 laser treatments. The number of lesions treated per session varied from 3 to 329. The median duration of regional control in all patients was 14 weeks (range, 3-117). In 9 of 22 patients, only 1 treatment with CO2 laser was performed resulting in a mean regional control of 11 weeks. In 10 patients, an average of 4 laser treatments (range, 1-17) was necessary to achieve regional control. Three of the 22 patients underwent isolated limb perfusion after laser treatment for disease control. This study shows that (repeated) laser treatment can achieve adequate regional control with little morbidity. CO2 laser is recommended as a first-line treatment to patients with small but numerous cutaneous satellite or in-transit lesions in whom other surgery would induce substantial morbidity.

Intraoral Laser Welding (ILW): ultrastructural and mechanical analysis

NASA Astrophysics Data System (ADS)

Fornaini, Carlo; Passaretti, Francesca; Villa, Elena; Nammour, Samir

2010-05-01

Nd:YAG, currently used since 1970 in dental laboratories to weld metals on dental prostheses has some limits such great dimensions, high costs and fixed delivery system. Recently it was proposed the possibility to use the Nd:YAG laser device commonly utilised in dental office, to repair broken fixed, removable and orthodontic prostheses and to weld metals directly into the mouth. The aim of this work is to value, through SEM (Scanning Electron Microscope), EDS (Energy Dispersive X-Ray Spectroscopy) and DMA (Dynamic Mechanical Analysis), quality and mechanical strength of the welding process comparing a device normally used in dental lab and a device normally used in dental office for oral surgery. Sixteen CoCrMo metal plates and twenty steel orthodontic wires were divided in four groups: one was welded without metal apposition by laboratory laser, one was welded with metal apposition by laboratory laser, one was welded without metal apposition by office laser and one was welded with metal apposition by office laser. The welding process was analysed by SEM, EDS and DMA to compare the differences between the different samples. By SEM analysis it was seen that the plates welded by office laser without apposition metal showed a greater number of fissurations compared with the other samples. By EDS analysis it was seen a homogeneous composition of the metals in all the samples. The mechanical tests showed a similar elastic behaviour of the samples, with minimal differences between the two devices. No wire broke even under the maximum strength by the Analyser. This study seems to demonstrate that the welding process by office Nd:YAG laser device and the welding process by laboratory Nd:YAG laser device, analysed by SEM, EDS and DMA, showed minimal and not significant differences even if these data will be confirmed by a greater number of samples.

Propagation of High Power Pulses of 10.6 micrometers Radiation from A CO2 TEA Laser of Novel Design through Clouds Produced by Adiabatic Expansion in the Laboratory

DTIC Science & Technology

1976-07-01

A AD PROPAGATION OF HIGH POWER PULSES OF 10.6 pm RADIATION FROM A C02 TEA LASER OF NOVEL DESIGN THROUGH CLOUDS PRODUCED BY ADIABATIC E•XPANS:’)N IN...PART A: CO2 LASER uEVELOPMENT Al High Power CO2 TEA Laser 2 A2 CW CO2 Laser 6 References 8 Diagrams 9 PART 8: CLOUD PROLDUCTION 61 Cloud Chamber...offer versatility, efficienr-y and high power . This report is concerned with the attenuation of 10.eum radiatiins, both high power pulsL.o and 04, by

Carbon dioxide laser versus erbium:YAG laser in treatment of epidermal verrucous nevus: a comparative randomized clinical study.

PubMed

Osman, Mai Abdel Raouf; Kassab, Ahmed Nazmi

2017-08-01

A verrucous epidermal nevus (VEN) is a skin disorder that has been treated using different treatment modalities with varying results. Ablative lasers such as carbon dioxide laser (CO 2 ) and erbium:yttrium-aluminum-garnet (Er:YAG) laser have been considered as the gold standard for the treatment of epidermal nevi. To evaluate and compare the efficacy, postoperative wound healing and side effects of pulsed CO 2 laser and Er:YAG laser for the treatment of verrucous epidermal nevi. Twenty patients with localized VEN were randomly divided into two groups. Group 1 was administered CO 2 laser and group 2 underwent Er:YAG laser treatment. A blinded physician evaluated the photographs and dermoscopic photomicrographs for the efficacy and possible side effects. All patients received one treatment session and were followed up over a 6-month period. Both lasers induced noticeable clinical improvement, but there were no significant differences between two lasers in treatment response, patient satisfaction, duration of erythema and side effects. The average time to re-epithelialization was 13.5 days with CO 2 and 7.9 days with Er:YAG laser (p< .0005). No scarring was observed in Er:YAG laser group and no lesional recurrence was detected in CO 2 laser group since treatment. Apart from re-epithelialization, both lasers showed equivalent outcomes with respect to treatment response, patient satisfaction, side effects and complications.

Pulsed infrared difference frequency generation in CdGeAs.sub.2

DOEpatents

Piltch, Martin S.; Rink, John P.; Tallman, Charles R.

1977-03-08

The disclosure relates to a laser apparatus for generating a line-tunable pulsed infrared difference frequency output. The apparatus comprises a CO.sub.2 laser which produces a first frequency, a CO laser which produces a second frequency and a mixer for combining the output of the CO.sub.2 and CO lasers so as to produce a final output comprising a difference frequency from the first and second frequency outputs.

Pulsed infrared difference frequency generation in CdGeAs/sub 2/

DOEpatents

Piltch, M.S.; Rink, J.P.; Tallman, C.R.

1975-11-26

A laser apparatus for generating a line-tunable pulsed infrared difference frequency output is described. The apparatus comprises a CO/sub 2/ laser which produces a first frequency, a CO laser which produces a second frequency, and a mixer for combining the output of the CO/sub 2/ and CO lasers so as to produce a final output comprising a difference frequency from the first and second frequency outputs.

Digital Holography for in Situ Real-Time Measurement of Plasma-Facing-Component Erosion

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

ThomasJr., C. E.; Granstedt, E. M.; Biewer, Theodore M

2014-01-01

In situ, real time measurement of net plasma-facing-component (PFC) erosion/deposition in a real plasma device is challenging due to the need for good spatial and temporal resolution, sufficient sensitivity, and immunity to fringe-jump errors. Design of a high-sensitivity, potentially high-speed, dual-wavelength CO2 laser digital holography system (nominally immune to fringe jumps) for PFC erosion measurement is discussed.

Effects of early combinatorial treatment of autologous split-thickness skin grafts in red duroc pig model using pulsed dye laser and fractional CO2 laser.

PubMed

Bailey, J Kevin; Blackstone, Britani N; DeBruler, Danielle M; Kim, Jayne Y; Baumann, Molly E; McFarland, Kevin L; Imeokparia, Folasade O; Supp, Dorothy M; Powell, Heather M

2018-01-01

The use of pulsed dye laser (PDL) and fractional CO 2 (FX CO 2 ) laser therapy to treat and/or prevent scarring following burn injury is becoming more widespread with a number of studies reporting reduction in scar erythema and pruritus following treatment with lasers. While the majority of studies report positive outcomes following PDL or FX CO 2 therapy, a number of studies have reported no benefit or worsening of the scar following treatment. The objective of this study was to directly compare the efficacy of PDL, FX CO 2 , and PDL + FX CO 2 laser therapy in reducing scarring post burn injury and autografting in a standardized animal model. Eight female red Duroc pigs (FRDP) received 4 standardized, 1 in. x 1 in. third degree burns that were excised and autografted. Wound sites were treated with PDL, FX CO 2 , or both at 4, 8, and 12 weeks post grafting. Grafts receiving no laser therapy served as controls. Scar appearance, morphology, size, and erythema were assessed and punch biopsies collected at weeks 4, 8, 12, and 16. At week 16, additional tissue was collected for biomechanical analyses and markers for inflammatory cytokines, extracellular matrix (ECM) proteins, re-epithelialization, pigmentation, and angiogenesis were quantified at all time points using qRT-PCR. Treatment with PDL, FX CO 2 , or PDL + FX CO 2 resulted in significantly less contraction versus skin graft only controls with no statistically significant difference among laser therapy groups. Scars treated with both PDL and FX CO 2 were visually more erythematous than other groups with a significant increase in redness between two and three standard deviations above normal skin redness. Scars treated with FX CO 2 were visually smoother and contained significantly fewer wrinkles. In addition, hyperpigmentation was significantly reduced in scars treated with FX CO 2 . The use of fractional carbon dioxide or pulsed dye laser therapy within 1 month of autografting significantly reduced scar contraction versus control, though no statistically significant difference was detected between laser modalities or use of both modalities. Overall, FX CO 2 therapy appears to be modestly more effective at reducing erythema, and improving scar texture and biomechanics. The current data adds to prior studies supporting the role of laser therapy in the treatment of burn scars and indicates more study is needed to optimize delivery protocols for maximum efficacy. Lasers Surg. Med. 50:78-87, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Laser treatment of solar lentigines on dorsum of hands: QS Ruby laser versus ablative CO2 fractional laser - a randomized controlled trial.

PubMed

Schoenewolf, Nicola L; Hafner, Jürg; Dummer, Reinhard; Bogdan Allemann, Inja

2015-04-01

Lentigines solares (LS) on the dorsum of hands are often esthetically disturbing. Q-switched ruby laser treatment is highly effective in the treatment of these lesions. Ablative fractional photothermolysis may be a suitable alternative. We compared the Q-switched ruby laser with ablative CO2 fractional photothermolysis for the treatment of solar lentigines. To evaluate the efficacy and side-effects of 694nm Q-switched ruby laser (Sinon) with the ablative 10,600nm CO2 fractional laser (Quantel Excel O2) in an intra-individual side-to-side comparison in the treatment of LS on the dorsum of hands. Eleven patients were included in the study. The hands of each patient were randomized for treatment with the two laser systems. Three treatment sessions were scheduled at weeks 0, 4 and 8. Evaluations by patients, treating physician and blinded experts were scheduled at weeks 0, 4, 8, 16 and 24. The Q-switched ruby laser was significantly more efficacious than the ablative CO2 fractional laser for removing LS on the dorsum of hands (p = 0.01). In this first study on this topic, the Q-switched ruby laser was superior to the ablative CO2 fractional laser in the treatment of lentigines solares on the dorsum of hands.

In Vitro Comparison of the Effects of Diode Laser and CO2 Laser on Topical Fluoride Uptake in Primary Teeth

PubMed Central

Bahrololoomi, Zahra; Sorouri, Milad

2015-01-01

Objectives: Fluoride therapy is important for control and prevention of dental caries. Laser irradiation can increase fluoride uptake especially when combined with topical fluoride application. The objective of this study was to compare the effects of CO2 and diode lasers on enamel fluoride uptake in primary teeth. Materials and Methods: Forty human primary molars were randomly assigned to four groups (n=10). The roots were removed and the crowns were sectioned mesiodistally into buccal and lingual halves as the experimental and control groups. All samples were treated with 5% sodium fluoride (NaF) varnish. The experimental samples in the four groups were irradiated with 5 or 7W diode or 1 or 2W CO2 laser for 15 seconds and were compared with the controls in terms of fluoride uptake, which was determined using an ion selective electrode after acid dissolution of the specimens. Data were analyzed by SPSS version 16 using ANOVA treating the control measurements as covariates. Results: The estimated amount of fluoride uptake was 59.5± 16.31 ppm, 66.5± 14.9 ppm, 78.6± 12.43 ppm and 90.4± 11.51 ppm for 5W and 7 W diode and 1W and 2 W CO2 lasers, respectively, which were significantly greater than the values in the conventional topical fluoridation group (P<0.005). There were no significant differences between 7W diode laser and 1W CO2 laser, 5W and 7W diode laser, or 1W and 2W CO2 laser in this regard. Conclusion: The results showed that enamel surface irradiation by CO2 and diode lasers increases the fluoride uptake. PMID:27123018

In Vitro Comparison of the Effects of Diode Laser and CO2 Laser on Topical Fluoride Uptake in Primary Teeth.

PubMed

Bahrololoomi, Zahra; Fotuhi Ardakani, Faezeh; Sorouri, Milad

2015-08-01

Fluoride therapy is important for control and prevention of dental caries. Laser irradiation can increase fluoride uptake especially when combined with topical fluoride application. The objective of this study was to compare the effects of CO2 and diode lasers on enamel fluoride uptake in primary teeth. Forty human primary molars were randomly assigned to four groups (n=10). The roots were removed and the crowns were sectioned mesiodistally into buccal and lingual halves as the experimental and control groups. All samples were treated with 5% sodium fluoride (NaF) varnish. The experimental samples in the four groups were irradiated with 5 or 7W diode or 1 or 2W CO2 laser for 15 seconds and were compared with the controls in terms of fluoride uptake, which was determined using an ion selective electrode after acid dissolution of the specimens. Data were analyzed by SPSS version 16 using ANOVA treating the control measurements as covariates. The estimated amount of fluoride uptake was 59.5± 16.31 ppm, 66.5± 14.9 ppm, 78.6± 12.43 ppm and 90.4± 11.51 ppm for 5W and 7 W diode and 1W and 2 W CO2 lasers, respectively, which were significantly greater than the values in the conventional topical fluoridation group (P<0.005). There were no significant differences between 7W diode laser and 1W CO2 laser, 5W and 7W diode laser, or 1W and 2W CO2 laser in this regard. The results showed that enamel surface irradiation by CO2 and diode lasers increases the fluoride uptake.

Comparison of four different lasers for acne scars: Resurfacing and fractional lasers.

PubMed

You, Hi-Jin; Kim, Deok-Woo; Yoon, Eul-Sik; Park, Seung-Ha

2016-04-01

Acne scars are common and cause cosmetic problems. There is a multitude of treatment options for acne scars, including dermabrasion, chemical peeling, and fillers, but the advent of laser technology has greatly improved the treatment of acne scars. Although several laser systems are available, studies comparing their efficacy are limited. This study compares the results of treatments using resurfacing (carbon dioxide, CO2; erbium-doped yttrium aluminum garnet, Er:YAG) versus fractional (nonablative fractional laser, NAFL; ablative fractional laser, AFL) lasers. A retrospective photographic analysis of 58 patients who underwent laser treatment for facial atrophic acne scars was performed. Clinical improvement was assessed by six blinded investigators with a scale graded from 0 to 10. Adverse events were also noted. Mean improvement scores of the CO2, Er:YAG, NAFL, and AFL groups were 6.0, 5.8, 2.2, and 5.2, respectively. The NAFL group showed a significantly lower score than the other groups. The mean number of treatments was significantly greater in the fractional laser groups than in the resurfacing laser groups. The resurfacing laser groups had a prolonged recovery period and high risk of complications. The Er:YAG laser caused less erythema or pigmentation compared to the CO2 laser. Although the CO2 laser, Er:YAG laser, and AFL improved the acne scars, the CO2 laser had a greater downtime. Three consecutive AFL treatments are as effective as a single treatment with resurfacing lasers, with shorter social downtime periods and less adverse effects. Copyright © 2016 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Effect of high power CO2 and Yb:YAG laser radiation on the characteristics of TIG arc in atmospherical pressure argon and helium

NASA Astrophysics Data System (ADS)

Wu, Shikai; Xiao, Rongshi

2015-04-01

The effects of laser radiation on the characteristics of the DC tungsten inert gas (TIG) arc were investigated by applying a high power slab CO2 laser and a Yb:YAG disc laser. Experiment results reveal that the arc voltage-current curve shifts downwards, the arc column expands, and the arc temperature rises while the high power CO2 laser beam vertically interacts with the TIG arc in argon. With the increase of the laser power, the voltage-current curve of the arc shifts downwards more significantly, and the closer the laser beam impingement on the arc to the cathode, the more the decrease in arc voltage. Moreover, the arc column expansion and the arc temperature rise occur mainly in the region between the laser beam incident position and the anode. However, the arc characteristics hardly change in the cases of the CO2 laser-helium arc and YAG laser-arc interactions. The reason is that the inverse Bremsstrahlung absorption coefficients are greatly different due to the different electron densities of the argon and helium arcs and the different wave lengths of CO2 and YAG lasers.

Assessment of radicular dentin permeability after irradiation with CO2 laser and endodontic irrigation treatments with thermal imaging

NASA Astrophysics Data System (ADS)

Cho, Heajin; Lee, Robert C.; Chan, Kenneth H.; Fried, Daniel

2017-02-01

Previous studies have demonstrated that the permeability changes due to the surface modification of dentin can be quantified via thermal imaging during dehydration. The CO2 laser has been shown to remove the smear layer and disinfect root canals. Moreover, thermal modification via CO2 laser irradiation can be used to convert dentin into a highly mineralized enamel-like mineral. The purpose of this study is to evaluate the radicular dentin surface modification after CO2 laser irradiation by measuring the permeability with thermal imaging. Human molar specimens (n=12) were sectioned into 4 axial walls of the pulp chamber and treated with either 10% NaClO for 1 minute, 5% EDTA for 1 minute, CO2 laser or none. The CO2 laser was operated at 9.4 μm with a pulse duration of 26 μs, pulse repetition rate of 300 Hz and a fluence of 13 J/cm2. The samples were dehydrated using an air spray for 60 seconds and imaged using a thermal camera. The resulting surface morphological changes were assessed using 3D digital microscopy. The images from digital microscopy confirmed melting of the mineral phase of dentin. The area enclosed by the time-temperature curve during dehydration, ▵Q, measured with thermal imaging increased significantly with treatments with EDTA and the CO2 laser (P<0.05). These results indicate that the surface modification due to CO2 laser treatment increases permeability of radicular dentin.

Fractional CO2 resurfacing: has it replaced ablative resurfacing techniques?

PubMed

Duplechain, Jesse Kevin

2013-05-01

The author uses the pulsed ablative CO2 laser regularly for skin rejuvenation. This decision is based on the gold standard status of the CO2 modality and an innovative aftercare treatment shown in the author's practice to greatly reduce the complications of ablative pulsed CO2 laser treatment. Depending on the patient and the severity of the skin condition, the author customizes each treatment, which may also include fractional CO2 lasers, fat grafting, facelifting, or any combination of these techniques. This article presents a detailed description of the evolution of skin rejuvenation with lasers and the current role of lasers as an adjunct to face and necklift surgery. Copyright © 2013 Elsevier Inc. All rights reserved.

The stability of the active medium of RF-exited CO2 lasers with gold as catalyst

NASA Astrophysics Data System (ADS)

Cherezov, V. M.; Novgorodov, M. Z.; Ochkin, V. N.; Samorodov, V. G.; Shishkanov, E. F.; Stepanov, V. A.; Witteman, W. J.

Using mass-spectrometric investigations the gas composition of the active medium of sealed-off cw RF-excited CO2 waveguide lasers have been studied. It has been found that a low degree of CO2 dissociation and a laser power improvement can be achieved by means of a gold catalyst in the laser discharge volume. The conditions for long operational lifetimes of these lasers are described.

Clinical application of CO2 laser in periodontal treatment

NASA Astrophysics Data System (ADS)

Hayase, Yasuhiro

1994-09-01

CO2 lasers in particular are expected to have many dental applications because the CO2 laser beam exhibits strong tissue transpirative actions, such as instant coagulation, carbonization, and vaporization, and because its wavelength at 10.6 micrometers is fully absorbed by water so that the ability to make precise incisions with a high degree of safety is excellent, without damaging the deep tissues. However, clinical application of the CO2 laser has been slowed since a fiber which can conduct the laser beam to the oral cavity has only recently developed. This new fiber is an extremely flexible fiber with a minimum bending radius of 20 mm and utilizes pulse wave modes that have improved the handling characteristics in the mouth, and this has enabled us to apply the CO2 laser to a variety of periodontal conditions. The aim of this study was to evaluate the effectiveness of CO2 lasers for the early treatment of inflammation and pain relief of acute periodontitis, curettage of periodontal pockets, healing after excision of gingiva, and early improvement of gingivitis.

Fast and versatile fabrication of PMMA microchip electrophoretic devices by laser engraving.

PubMed

Moreira Gabriel, Ellen Flávia; Tomazelli Coltro, Wendell Karlos; Garcia, Carlos D

2014-08-01

This paper describes the effects of different modes and engraving parameters on the dimensions of microfluidic structures produced in PMMA using laser engraving. The engraving modes included raster and vector, while the explored engraving parameters included power, speed, frequency, resolution, line-width, and number of passes. Under the optimum conditions, the technique was applied to produce channels suitable for CE separations. Taking advantage of the possibility to cut-through the substrates, the laser was also used to define solution reservoirs (buffer, sample, and waste) and a PDMS-based decoupler. The final device was used to perform the analysis of a model mixture of phenolic compounds within 200 s with baseline resolution. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A fast and low-cost microfabrication approach for six types of thermoplastic substrates with reduced feature size and minimized bulges using sacrificial layer assisted laser engraving.

PubMed

Gu, Longjun; Yu, Guodong; Li, Cheuk-Wing

2018-01-02

Since polydimethylsiloxane (PDMS) is notorious for its severe sorption to biological compounds and even nanoparticles, thermoplastics become a promising substrate for microdevices. Although CO 2 laser engraving is an efficient method for thermoplastic device fabrication, it accompanies with poor bonding issues due to severe bulging and large feature size determined by the diameter of laser beam. In this study, a low-cost microfabrication method is proposed by reversibly sealing a 1 mm thick polymethylmethacrylate (PMMA) over an engraving substrate to reduce channel feature size and minimize bulges of laser engraved channels. PMMA, polycarbonate (PC), polystyrene (PS), perfluoroalkoxy alkane (PFA), cyclic-olefin polymers (COP) and polylactic acid (PLA) were found compatible with this sacrificial layer assisted laser engraving technique. Microchannel width as small as ∼40 μm was attainable by a laser beam that was 5 times larger in diameter. Bulging height was significantly reduced to less 5 μm for most substrates, which facilitated leak proof device bonding without channel deformation. Microdevices with high aspect ratio channels were prepared to demonstrate the applicability of this microfabrication method. We believe this fast and low-cost fabrication approach for thermoplastics will be of interest to researchers who have encountered problem with polydimethylsiloxane based microdevices in their applications. Copyright © 2017 Elsevier B.V. All rights reserved.

10-year experience of CO2-laser application in ambulance gynecology

NASA Astrophysics Data System (ADS)

Stachanov, Michael L.; Masychev, Victor I.; Velsher, Leonid Z.; Kirkin, Vladimir V.; Zhashkov, Roman V.; Kocharian, Emilia A.

2000-10-01

CO2-laser surgical systems have come to stay in everyday practice of modern physicians and are successfully used in colposcopic and laparoscopic surgery. Results, obtained in ambulance gynecology are especially impressing. CO2- laser provides high medical- and cost-effective treatment. Presented work describes many-years experience of CO2- laser application. 439 patients with various vulvaric and cervix diseases were operated within this period. Laser beam parameters were selected according to requirements ((tau) =4 J/cm2) treatment without carbonization. Analyses of the results showed that the laser successfully destructs uterine cervix erosion, endocervicosis, dysplasia, leukoplakia, eritoplakia of uterine cervix, various benignant pathologies and focus degenerative process in ambulate conditions.

Comparison of effects of diode laser and CO2 laser on human teeth and their usefulness in topical fluoridation.

PubMed

González-Rodríguez, Alberto; de Dios López-González, Juan; del Castillo, Juan de Dios Luna; Villalba-Moreno, Juan

2011-05-01

Various authors have reported more effective fluoridation from the use of lasers combined with topical fluoride than from conventional topical fluoridation. Besides the beneficial effect of lasers in reducing the acid solubility of an enamel surface, they can also increase the uptake of fluoride. The study objectives were to compare the action of CO(2) and GaAlAs diode lasers on dental enamel and their effects on pulp temperature and enamel fluoride uptake. Different groups of selected enamel surfaces were treated with amine fluoride and irradiated with CO(2) laser at an energy power of 1 or 2 W or with diode laser at 5 or 7 W for 15 s each and compared to enamel surfaces without treatment or topical fluoridated. Samples were examined by means of environmental scanning electron microscopy (ESEM). Surfaces of all enamel samples were then acid-etched, measuring the amount of fluoride deposited on the enamel by using a selective ion electrode. Other enamel surfaces selected under the same conditions were irradiated as described above, measuring the increase in pulp temperature with a thermocouple wire. Fluorination with CO(2) laser at 1 W and diode laser at 7 W produced a significantly greater fluoride uptake on enamel (89 ± 18 mg/l) and (77 ± 17 mg/l) versus topical fluoridation alone (58 ± 7 mg/l) and no treatment (20 ± 1 mg/l). Diode laser at 5 W produced a lesser alteration of the enamel surface compared to CO(2) laser at 1 W, but greater pulp safety was provided by CO(2) laser (ΔT° 1.60° ± 0.5) than by diode laser (ΔT° 3.16° ± 0.6). Diode laser at 7 W and CO(2) laser at 2 W both caused alterations on enamel surfaces, but great pulp safety was again obtained with CO(2) (ΔT° 4.44° ± 0.60) than with diode (ΔT° 5.25° ± 0.55). Our study demonstrates that CO(2) and diode laser irradiation of the enamel surface can both increase fluoride uptake; however, laser energy parameters must be carefully controlled in order to limit increases in pulpal temperature and alterations to the enamel surface.

Comparing mechanical effects and sound production of KTP, thulium, and CO2 laser in stapedotomy.

PubMed

Kamalski, Digna M A; Verdaasdonk, Rudolf M; de Boorder, Tjeerd; Vincent, Robert; Versnel, Huib; Grolman, Wilko

2014-08-01

The mechanical and acoustic effects that occur during laser-assisted stapedotomy differ among KTP, CO2, and thulium lasers. Making a fenestration in stapedotomy with a laser minimizes the risk of a floating footplate caused by mechanical forces. Theoretically, the lasers used in stapedotomy could inflict mechanical trauma because of absorption in the perilymph, causing vaporization bubbles. These bubbles can generate a shock wave, when imploding. In an inner ear model, we made a fenestration in a fresh human stapes with KTP, CO2, and thulium laser. During the fenestration, we performed high-speed imaging from different angles to capture mechanical effects. The sounds produced by the fenestration were recorded simultaneously with a hydrophone; these recordings were compared with acoustics produced by a conventional microburr fenestration. KTP laser fenestration showed little mechanical effects, with minimal sound production. With CO2 laser, miniscule bubbles arose in the vestibule; imploding of these bubbles corresponded to the acoustics. Thulium laser fenestration showed large bubbles in the vestibule, with a larger sound production than the other two lasers. Each type of laser generated significantly less noise than the microburr. The microburr maximally reached 95 ± 7 dB(A), compared with 49 ± 8 dB(A) for KTP, 68 ± 4 dB(A) for CO2, and 83 ± 6 dB(A) for thulium. Mechanical and acoustic effects differ among lasers used for stapedotomy. Based on their relatively small effects, KTP and CO2 lasers are preferable to thulium laser.

Laser detection of CO2 concentration in human breath at various diseases

NASA Astrophysics Data System (ADS)

Ageev, Boris G.; Nikiforova, Olga Y.

2015-12-01

Absorption spectra of human breath in 10 μm region were recorded by the use of intracavity laser photo-acoustic gas analyzer based on tunable waveguide CO2 laser. Healthy persons and patients with various diseases were studied. For determination of CO2 concentration in exhalation samples gas analyzer was calibrated by reference gaseous mixture CO2-N2. It was obtained that CO2 concentration values in human breath of healthy persons are greater than that of patients with various diseases.

Mode selection and frequency tuning by injection in pulsed TEA-CO2 lasers

NASA Technical Reports Server (NTRS)

Flamant, P. H.; Menzies, R. T.

1983-01-01

An analytical model characterizing pulsed-TEA-CO2-laser injection locking by tunable CW-laser radiation is presented and used to explore the requirements for SLM pulse generation. Photon-density-rate equations describing the laser mechanism are analyzed in terms of the mode competition between photon densities emitted at two frequencies. The expression derived for pulsed dye lasers is extended to homogeneously broadened CO2 lasers, and locking time is defined as a function of laser parameters. The extent to which injected radiation can be detuned from the CO2 line center and continue to produce SLM pulses is investigated experimentally in terms of the analytical framework. The dependence of locking time on the detuning/pressure-broadened-halfwidth ratio is seen as important for spectroscopic applications requiring tuning within the TEA-laser line-gain bandwidth.

Carbon dioxide laser for detrusor tunnel creation in robot-assisted laparoscopic extravesical ureteral reimplant.

PubMed

Diaz, E C; Lindgren, B W; Gong, E M

2014-12-01

Demonstrate and report initial results using a carbon dioxide (CO2) laser for detrusor tunnel creation in robot-assisted laparoscopic extravesical ureteral reimplant (RALUR). Retrospective chart review was performed for cases of RALUR from 2011 to 2014. Patients undergoing complex reconstruction (ureteral tailoring, dismembered reimplant, concomitant ureteroureterostomy), and those who had incomplete follow-up were excluded. Variables, including use of the CO2 laser, were collected and correlated with outcomes. 23 patients representing 40 ureteral units were included for analysis. A CO2 laser was used in 9/23 (39%) patients and 16/40 (40%) ureteral units. Intraoperative mucosotomy was reported in 3/14 (21%) patients for the electrocautery group and 1/9 (11%) patients for the CO2 laser group. Resolution of VUR was observed in 11/14 (79%), and 9/9 (100%) of patients for the electrocautery group and the CO2 laser group, respectively. Two complications were identified in the electrocautery group of patients: ileus (Clavien 2), and transient bilateral ureteral obstruction requiring placement of ureteral stents (Clavien 3B). There were no complications in the CO2 laser group. Creation of the detrusor tunnel with a CO2 laser is safe and effective, and is associated with a lower rate of failure and complication in this cohort. Copyright © 2014 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.

Laser-induced lipolysis on adipose cells

NASA Astrophysics Data System (ADS)

Solarte, Efrain; Gutierrez, O.; Neira, Rodrigo; Arroyave, J.; Isaza, Carolina; Ramirez, Hugo; Rebolledo, Aldo F.; Criollo, Willian; Ortiz, C.

2004-10-01

Recently, a new liposuction technique, using a low-level laser (LLL) device and Ultrawet solution prior to the procedure, demonstrated the movement of fat from the inside to the outside of the adipocyte (Neira et al., 2002). To determine the mechanisms involved, we have performed Scanning and Transmission Electron Microscopy studies; Light transmittance measurements on adipocyte dilutions; and a study of laser light propagation in adipose tissue. This studies show: 1. Cellular membrane alterations. 2. LLL is capable to reach the deep adipose tissue layer, and 3. The tumescence solution enhances the light propagation by clearing the tissue. MRI studies demonstrated the appearance of fat on laser treated abdominal tissue. Besides, adipocytes were cultivated and irradiated to observe the effects on isolated cells. These last studies show: 1. 635 nm-laser alone is capable of mobilizing cholesterol from the cell membrane; this action is enhanced by the presence of adrenaline and lidocaine. 2. Intracellular fat is released from adipocytes by co joint action of adrenaline, aminophyline and 635 nm-laser. Results are consistent with a laser induced cellular process, which causes fat release from the adipocytes into the intercellular space, besides the modification of the cellular membranes.

Pulpal safety of a 9.6-μm TEA CO2 laser used for caries prevention

NASA Astrophysics Data System (ADS)

Goodis, Harold E.; Fried, Daniel; Featherstone, John D. B.

2002-06-01

Lasers are used for several procedures involving hard and soft tissues of the oral cavity. Included in those procedures is the use of the CO2 laser to alter the surface structure of tooth enamel to render it more resistant to caries. A new 9.6micrometers wavelength TEA CO2 laser (Argu Photonics, Jpiter, FL) has been investigated as a device that can be used for this procedure without harming the dental pulp. Erupted, caries and restoration free third molars (n=24) were used in the experiment. Teeth were irradiated at an incident fluence of 1.5J/cm2 and a repetition rate of 10Hz and a spot size 1mm in diameter. At the low and high settings, 200 to 400 pulses were delivered at 12mJ per pulse for a total energy of 2.4 or 4.8J delivered for 20 or 40 seconds respectively. Other teeth were subjected to a sham dental procedure (positive control) or no procedure (negative control). Prior to testing, radiographs were taken of all teeth, and they were tested pulpally using heat, cold and electricity to determine vitality. The teeth were removed either immediately or at one week or one month after testing. They were bioprepared and examined histologically for signs of inflammation. Only one tooth developed symptoms of sensitivity to cold for 10 days following exposure to the high power level. The sensitivity was of fleeting duration and was judged to be reversible pulpitis. All teeth tested responded normally at pretesting and pre-extraction time periods. Histological examination disclosed no indication of an inflammatory response in the pulp tissue. All sections appeared normal with no changes seen in the normal pulpal morphology. We conclude that the 9.6 micrometers wavelength laser causes no pulpal damage at the energy levels used and can be used safely for caries prevention treatments.

Antibacterial and Odontogenesis Efficacy of Mineral Trioxide Aggregate Combined with CO2 Laser Treatment.

PubMed

Hsu, Tuan-Ti; Yeh, Chia-Hung; Kao, Chia-Tze; Chen, Yi-Wen; Huang, Tsui-Hsien; Yang, Jaw-Ji; Shie, Ming-You

2015-07-01

Mineral trioxide aggregate (MTA) has been successfully used in clinical applications in endodontics. Studies show that the antibacterial effects of CO2 laser irradiation are highly efficient when bacteria are embedded in biofilm because of a photothermal mechanism. The aim of this study was to confirm the effects of CO2 laser irradiation on MTA with regard to both material characterization and cell viability. MTA was irradiated with a dental CO2 laser using directly mounted fiber optics in the wound healing mode with a spot area of 0.25 cm(2) and then stored in an incubator at 100% relative humidity and 37°C for 1 day to set. The human dental pulp cells cultured on MTA were analyzed along with their proliferation and odontogenic differentiation behaviors. The results indicate that the setting time of MTA after irradiation by the CO2 laser was significantly reduced to 118 minutes rather than the usual 143 minutes. The maximum diametral tensile strength and x-ray diffraction patterns were similar to those obtained without CO2 laser irradiation. However, the CO2 laser irradiation increased the amount of Ca and Si ions released from the MTA and regulated cell behavior. CO2 laser-irradiated MTA promoted odontogenic differentiation of hDPCs, with the increased formation of mineralized nodules on the substrate's surface. It also up-regulated the protein expression of multiple markers of odontogenic and the expression of dentin sialophosphoprotein protein. The current study provides new and important data about the effects of CO2 laser irradiation on MTA with regard to the decreased setting time and increased ion release. Taking cell functions into account, the Si concentration released from MTA with laser irradiation may be lower than a critical value, and this information could lead to the development of new regenerative therapies for dentin and periodontal tissue. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Comparison of Q-switched Nd: YAG laser and fractional carbon dioxide laser for the treatment of solar lentigines in Asians.

PubMed

Vachiramon, Vasanop; Panmanee, Wikanda; Techapichetvanich, Thanya; Chanprapaph, Kumutnart

2016-04-01

Solar lentigines are benign pigmented lesions that occur mostly on sun-exposed areas. Q-switched and ablative lasers are effective for removing these lesions but the high incidence of postinflammatory hyperpigmentation raises concern in darker skin types. The objective of this study is to compare the efficacy and degree of postinflammatory hyperpigmentation with the Q-switched Nd:YAG and fractional carbon dioxide (CO2 ) laser for treatment of solar lentigines in Asians. Twenty-five Thai patients (skin phototype III-IV) with at least two lesions of solar lentigines on upper extremities were enrolled in this study. Two lesions were randomly selected for the treatment with a single session of Q-switched Nd:YAG or fractional CO2 laser. Outcomes were evaluated using physician grading scale, colorimeter, and patient self-assessment at 6 and 12 weeks after treatment. Side effects were recorded. A total of 532 nm Q-switched Nd:YAG laser showed significant improvement of pigmentation over fractional CO2 laser at 6th and 12th week by both colorimeter assessment and physician grading scale (P < 0.05). No significant difference in postinflammatory hyperpigmentation from both lasers was observed. In terms of patient self-assessment, 80% of the patients treated with 532 nm Q-switched Nd:YAG laser had excellent results compared to 8% in fractional CO2 laser group. However, fractional CO2 laser treatment had faster healing time and less pain score compared to Q-switched Nd:YAG laser. Q-switched Nd:YAG is superior to fractional CO2 laser for treatment of solar lentigines but requires longer healing time and produces more pain. The incidence of postinflammatory hyperpigmentation was not significantly different with both lasers. Further studies are needed to obtain the proper parameter and the treatment frequency of fractional CO2 laser in solar lentigines. © 2016 Wiley Periodicals, Inc.

Fractional CO2 laser treatment for vaginal laxity: A preclinical study.

PubMed

Kwon, Tae-Rin; Kim, Jong Hwan; Seok, Joon; Kim, Jae Min; Bak, Dong-Ho; Choi, Mi-Ji; Mun, Seok Kyun; Kim, Chan Woong; Ahn, Seungwon; Kim, Beom Joon

2018-05-07

Various studies have investigated treatment for vaginal laxity with microablative fractional carbon dioxide CO 2 laser in humans; however, this treatment has not yet been studied in an animal model. Herein, we evaluate the therapeutic effects of fractional CO 2 laser for tissue remodeling of vaginal mucosa using a porcine model, with the aim of improving vaginal laxity. The fractional CO 2 laser enables minimally invasive and non-incisional procedures. By precisely controlling the laser energy pulses, energy is sent to the vaginal canal and the introitus area to induce thermal denaturation and contraction of collagen. We examined the effects of fractional CO 2 laser on a porcine model via clinical observation and ultrasound measurement. Also, thermal lesions were histologically examined via hematoxylin-eosin staining, Masson's trichrome staining, and Elastica van Gieson staining and immunohistochemistry. The three treatment groups, which were determined according to the amount of laser-energy applied (60, 90, and 120 mJ), showed slight thermal denaturation in the vaginal mucosa, but no abnormal reactions, such as excessive hemorrhaging, vesicles, or erythema, were observed. Histologically, we also confirmed that the denatured lamina propria induced by fractional CO 2 laser was dose-dependently increased after laser treatment. The treatment groups also showed an increase in collagen and elastic fibers due to neocollagenesis and angiogenesis, and the vaginal walls became firmer and tighter because of increased capillary and vessel formation. Also, use of the fractional CO 2 laser increased HSP (heat shock protein) 70 and collagen type I synthesis. Our results show that microablative fractional CO 2 laser can produce remodeling of the vaginal connective tissue without causing damage to surrounding tissue, and the process of mucosa remodeling while under wound dressings enables collagen to increase and the vaginal wall to become thick and tightened. Lasers Surg. Med. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

Computer modeling of pulsed CO2 lasers for lidar applications

NASA Technical Reports Server (NTRS)

Spiers, Gary D.

1993-01-01

The object of this effort is to develop code to enable the accurate prediction of the performance of pulsed transversely excited (TE) CO2 lasers prior to their construction. This is of particular benefit to the NASA Laser Atmospheric Wind Sounder (LAWS) project. A benefit of the completed code is that although developed specifically for the pulsed CO2 laser much of the code can be modified to model other laser systems of interest to the lidar community. A Boltzmann equation solver has been developed which enables the electron excitation rates for the vibrational levels of CO2 and N2, together with the electron ionization and attachment coefficients to be determined for any CO2 laser gas mixture consisting of a combination of CO2, N2, CO, He and CO. The validity of the model has been verified by comparison with published material. The results from the Boltzmann equation solver have been used as input to the laser kinetics code which is currently under development. A numerical code to model the laser induced medium perturbation (LIMP) arising from the relaxation of the lower laser level has been developed and used to determine the effect of LIMP on the frequency spectrum of the LAWS laser output pulse. The enclosed figures show representative results for a laser operating at 0.5 atm. with a discharge cross-section of 4.5 cm to produce a 20 J pulse with aFWHM of 3.1 microns. The first four plots show the temporal evolution of the laser pulse power, energy evolution, LIMP frequency chirp and electric field magnitude. The electric field magnitude is taken by beating the calculated complex electric field and beating it with a local oscillator signal. The remaining two figures show the power spectrum and energy distribution in the pulse as a function of the varying pulse frequency. The LIMP theory has been compared with experimental data from the NOAA Windvan Lidar and has been found to be in good agreement.

Complication and recurrence rate in laser CO2 versus traditional surgery in the treatment of Bartholin's gland cyst.

PubMed

Frega, Antonio; Schimberni, Mauro; Ralli, Eleonora; Verrone, Antonella; Manzara, Federica; Schimberni, Matteo; Nobili, Flavia; Caserta, Donatella

2016-08-01

The treatment of Bartholin's gland cysts by traditional surgery is characterized by some disadvantages and complications such as hemorrhage, postoperative dyspareunia, infections, necessity for a general anesthesia. Contrarily, CO2 laser surgery might be less invasive and more effective as it solves many problems of traditional surgery. The aim of our study is to describe CO2 laser technique evaluating its feasibility, complication rate and results vs traditional surgery. Among patients treated for Bartholin's gland cyst, we enrolled 62 patients comparing traditional surgical excision vs CO2 laser surgery of whom 27 patients underwent traditional surgery, whereas 35 patients underwent CO2 laser surgery. Mean operative time, complication rate, recurrence rate and short- and long-term outcomes were assessed. The procedures required a mean operative time of 9 ± 5.3 min for CO2 laser surgery and 42.2 ± 13.8 for traditional surgery. Two patients (5.7 %) needed an hemostatic suture for intraoperative bleeding in the laser CO2 laser technique against 14.8 % for traditional surgery. Carbon dioxide allows a complete healing in a mean time of 22 days without scarring, hematomas or wound infections and a return to daily living in a mean time of 2 days. Instead, patients undergone traditional surgery required a mean time of 14 days to return to daily life with a healing mean time completed in 28 days. The minimum rate of intra- and post-operative complications, the ability to perform it under local anesthesia in an outpatient setting make CO2 laser surgery more cost-effective than traditional surgery.

Threshold analysis of pulsed lasers with application to a room-temperature Co:MgF2 laser

NASA Technical Reports Server (NTRS)

Harrison, James; Welford, David; Moulton, Peter F.

1989-01-01

Rate-equation calculations are used to model accurately the near-threshold behavior of a Co:MgF2 laser operating at room temperature. The results demonstrate the limitations of the conventional threshold analysis in cases of practical interest. This conclusion is applicable to pulsed solid-state lasers in general. The calculations, together with experimental data, are used to determine emission cross sections for the Co:MgF2 laser.

Controlling chaotic behavior in CO2 and other lasers

NASA Astrophysics Data System (ADS)

1993-06-01

Additional substantial experimental progress has been made, in the third month of the project, in setting up equipment and testing for producing chaotic behavior with a CO2 laser. The project goal is to synchronize and control chaos in CO2 and other lasers, and thereby increase the power in ensembles of coupled laser sources. Numerous investigations into the chaos regime have been made, a second CO2 laser has been brought on stream, and work is progressing in the fourth month toward coupling the two lasers and control of the first laser. It is also intended to submit at least two papers to the Second Experimental Chaos Conference which is supported by the Office of Naval Research. Abstracts to those two papers are attached. Last month's report discussed the experimental investigation of nonlinear dynamics of CO2 lasers which involved a new technique of inducing chaos. In this new technique, an acoustically modulated feedback of the laser light was used and led to chaotic dynamics at a very low modulation frequency of 375 Hz. Since then, new results have been obtained by an Electro-Optical Modulation (EOM) technique. In the new setup, the electro-optical modulator is placed in an external cavity outside the laser.

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.

Characterization of the isolated [Co3Ni (EtOH )] + cluster by IR spectroscopy and spin-dynamics calculations

NASA Astrophysics Data System (ADS)

Dutta, D.; Becherer, M.; Bellaire, D.; Dietrich, F.; Gerhards, M.; Lefkidis, G.; Hübner, W.

2018-06-01

We experimentally and theoretically study the geometry, as well as the electronic and vibrational properties, of the heterotetranuclear magnetic cluster [Co3Ni (EtOH )] +, which is prepared in the gas phase with molecular beam expansion. We characterize the cluster and identify possible isomers through the comparison of experimentally observed infrared spectra with state-of-the-art quantum chemistry calculations, more specifically by focusing on the OH stretching frequency. Furthermore, we suggest ultrafast, laser-induced, local spin-flip scenarios on every Co atom, and report a cooperative effect, in which the spin density is localized on one Co atom, gets transiently transferred to another, and then bounces back pointing in the opposite direction. Finally, we predict a tolerance of the suggested scenarios with respect to the laser detuning of about 20 meV, which lies within an experimentally applicable range. Our joint investigation is an additional step toward the implementation of laser-controlled nanospintronic devices.

Comparison of ultrasonic and CO₂laser pretreatment methods on enzyme digestibility of corn stover.

PubMed

Tian, Shuang-Qi; Wang, Zhen-Yu; Fan, Zi-Luan; Zuo, Li-Li

2012-01-01

To decrease the cost of bioethanol production, biomass recalcitrance needs to be overcome so that the conversion of biomass to bioethanol becomes more efficient. CO(2) laser irradiation can disrupt the lignocellulosic physical structure and reduce the average size of fiber. Analyses with Fourier transform infrared spectroscopy, specific surface area, and the microstructure of corn stover were used to elucidate the enhancement mechanism of the pretreatment process by CO(2) laser irradiation. The present work demonstrated that the CO(2) laser had potential to enhance the bioconversion efficiency of lignocellulosic waste to renewable bioethanol. The saccharification rate of the CO(2) laser pretreatment was significantly higher than ultrasonic pretreatment, and reached 27.75% which was 1.34-fold of that of ultrasonic pretreatment. The results showed the impact of CO(2) laser pretreatment on corn stover to be more effective than ultrasonic pretreatment.

Treatment of Bartholin gland cyst with CO2 laser

PubMed Central

Speck, Neila Maria de Góis; Boechat, Karol Pereira Ruela; dos Santos, Georgia Mouzinho Lima; Ribalta, Julisa Chamorro Lascasas

2016-01-01

ABSTRACT Objective To describe the results of treatment with CO2 laser for Bartholin gland cysts. Methods Thirty-one women with Bartholin gland cysts were treated with CO2 laser at an outpatient´s setting. Skin incision was performed with focused laser beam, the capsule was opened to drain mucoid content, followed by internal vaporization of impaired capsule. Results There were no complications. Five patients had recurrence of the cyst and were submitted to a second and successful session. Conclusion CO2 laser surgery was effective to treat Bartholin gland cysts with minimal or no complications, and can be performed at an outpatient´s setting. PMID:27074230

CO2 laser oscillators for laser radar applications

NASA Technical Reports Server (NTRS)

Freed, C.

1990-01-01

This paper reviews the spectral purity, frequency stability, and long-term stabilization of newly developed CO2 isotope lasers. Extremely high spectral purity, and short-term stability of less than 1.5 x 10 to the -13th have been achieved. A brief description on using CO2 isotope lasers as secondary frequency standards and in optical radar is given. The design and output characteristics of a single frequency, TEM00q mode, variable pulse width, hybrid TE CO2 laser system is also described. The frequency chirp in the output has been measured and almost completely eliminated by means of a novel technique.

Spin wave propagation detected over 100 μm in half-metallic Heusler alloy Co2MnSi

NASA Astrophysics Data System (ADS)

Stückler, Tobias; Liu, Chuanpu; Yu, Haiming; Heimbach, Florian; Chen, Jilei; Hu, Junfeng; Tu, Sa; Alam, Md. Shah; Zhang, Jianyu; Zhang, Youguang; Farrell, Ian L.; Emeny, Chrissy; Granville, Simon; Liao, Zhi-Min; Yu, Dapeng; Zhao, Weisheng

2018-03-01

The field of magnon spintronics offers a charge current free way of information transportation by using spin waves (SWs). Compared to forward volume spin waves for example, Damon-Eshbach (DE) SWs need a relatively weak external magnetic field which is suitable for small spintronic devices. In this work we study DE SWs in Co2MnSi, a half-metallic Heusler alloy with significant potential for magnonics. Thin films have been produced by pulsed laser deposition. Integrated coplanar waveguide (CPW) antennas with different distances between emitter and detection antenna have been prepared on a Co2MnSi film. We used a vector network analyzer to measure spin wave reflection and transmission. We observe spin wave propagation up to 100 μm, a new record for half-metallic Heusler thin films.

Applications of high power lasers. [using reflection holograms for machining and surface treatment

NASA Technical Reports Server (NTRS)

Angus, J. C.

1979-01-01

The use of computer generated, reflection holograms in conjunction with high power lasers for precision machining of metals and ceramics was investigated. The Reflection holograms which were developed and made to work at both optical wavelength (He-Ne, 6328 A) and infrared (CO2, 10.6) meet the primary practical requirement of ruggedness and are relatively economical and simple to fabricate. The technology is sufficiently advanced now so that reflection holography could indeed be used as a practical manufacturing device in certain applications requiring low power densities. However, the present holograms are energy inefficient and much of the laser power is lost in the zero order spot and higher diffraction orders. Improvements of laser machining over conventional methods are discussed and addition applications are listed. Possible uses in the electronics industry include drilling holes in printed circuit boards making soldered connections, and resistor trimming.

Ambient-temperature co-oxidation catalysts

NASA Technical Reports Server (NTRS)

Upchurch, Billy T.; Schryer, David R.; Brown, Kenneth G.; Kielin, Erik J.

1991-01-01

Oxidation catalysts which operate at ambient temperature were developed for the recombination of carbon monoxide (CO) and oxygen (O2) dissociation products which are formed during carbon dioxide (CO2) laser operation. Recombination of these products to regenerate CO2 allows continuous operation of CO2 lasers in a closed cycle mode. Development of these catalyst materials provides enabling technology for the operation of such lasers from space platforms or in ground based facilities without constant gas consumption required for continuous open cycle operation. Such catalysts also have other applications in various areas outside the laser community for removal of CO from other closed environments such as indoor air and as an ambient temperature catalytic converter for control of auto emissions.

Low-Temperature CO-Oxidation Catalysts for Long-Life CO2 Lasers

NASA Technical Reports Server (NTRS)

Schryer, David R. (Editor); Hoflund, Gar B. (Editor)

1990-01-01

Low-temperature CO-oxidation catalysts are necessary for closed-cycle pulsed CO2 lasers as well as for other applications, including air purification. The papers presented in this volume discuss several such catalysts, including information on catalyst preparation, techniques for enhancing catalyst performance, laboratory and laser test results, and mechanistic considerations.

Thermoplastic microchannel fabrication using carbon dioxide laser ablation.

PubMed

Wang, Shau-Chun; Lee, Chia-Yu; Chen, Hsiao-Ping

2006-04-14

We report the procedures of machining microchannels on Vivak co-polyester thermoplastic substrates using a simple industrial CO(2) laser marker. To avoid overheating the substrates, we develop low-power marking techniques in nearly anaerobic environment. These procedures are able to machine microchannels at various aspect ratios. Either straight or serpent channel can be easily marked. Like the wire-embossed channel walls, the ablated channel surfaces become charged after alkaline hydrolysis treatment. Stable electroosmotic flow in the charged conduit is observed to be of the same order of magnitude as that in fused silica capillary. Typical dynamic coating protocols to alter the conduit surface properties are transferable to the ablated channels. The effects of buffer acidity on electroosmotic mobility in both bare and coated channels are similar to those in fused silica capillaries. Using video microscopy we also demonstrate that this device is useful in distinguishing the electrophoretic mobility of bare and latex particles from that of functionalized ones.

Evaluation of fracture toughness of ZrO 2 and Si 3N 4 engineering ceramics following CO 2 and fibre laser surface treatment

NASA Astrophysics Data System (ADS)

Shukla, P. P.; Lawrence, J.

2011-02-01

The fracture toughness property ( K1C) of Si 3N 4 and ZrO 2 engineering ceramics was investigated by means of CO 2 and a fibre laser surface treatment. Near surface modifications in the hardness were investigated by employing the Vickers indentation method. Crack lengths and the crack geometry were then measured by using the optical microscopy. A co-ordinate measuring machine was used to investigate the diamond indentations and to measure the lengths of the cracks. Thereafter, computational and analytical methods were employed to determine the K1C. An increase in the K1C of both ceramics was found by the CO 2 and the fibre laser surface treatment in comparison to the as-received surfaces. The K1C of the CO 2 laser radiated surface of the Si 3N 4 was over 3% higher in comparison to that of the fibre laser treated surface. This was by softening of the near surface layer of the Si 3N 4 which comprised of lowering of hardness, which in turn increased the crack resistance. The effects were not similar in ZrO 2 ceramic to that of the Si 3N 4 as the fibre laser radiation in this case had produced an increase of 34% compared to that of the CO 2 laser radiation. This occurred due to propagation of lower crack resulting from the Vickers indentation test during the fibre laser surface treatment which inherently affected the end K1C through an induced compressive stress layer. The K1C modification of the two ceramics treated by the CO 2 and the fibre laser was also believed to be influenced by the different laser wavelength and its absorption co-efficient, the beam delivery system as well as the differences in the brightness of the two lasers used.

Airborne Lidar measurements of Atmospheric CO2 Column Absorption and Line Shapes from 3-11 km altitudes

NASA Astrophysics Data System (ADS)

Abshire, J. B.; Riris, H.; Allan, G. R.; Weaver, C.; Mao, J.; Hasselbrack, W.

2009-04-01

Accurate measurements of tropospheric CO2 abundances with global-coverage are needed to quantify processes that regulate CO2 exchange with the land and oceans. The 2007 Decadal Survey for Earth Science by the US National Research Council recommended a space-based CO2 measuring mission called ASCENDS. We have been developing a technique for the remote measurement of tropospheric CO2 concentrations from aircraft and as a candidate for the ASCENDS mission. It uses the 1570-nm CO2 band and a dual channel laser absorption spectrometer (ie DIAL used in altimeter mode). It uses several tunable laser transmitters allowing simultaneous measurement of the absorption from a CO2 absorption line in the 1570 nm band, O2 extinction in the oxygen A-band, and surface height and aerosol backscatter in the same path. It directs the narrow co-aligned laser beams toward nadir, and measures the energy of the laser echoes reflected from land and water surfaces. During the measurement, the lasers are stepped in wavelength across the CO2 line and an O2 line (near 765 nm) at a ~ 1 kHz rate. The receiver uses a telescope and photon counting detectors, and measures the background light and energies of the laser echoes from the surface along with scattering from any aerosols in the path. The gas extinction and column densities for the CO2 and O2 gases are estimated from the ratio of the on- and off- line signals via the DIAL technique. We use pulsed laser signals and time gating to isolate the laser echo signals from the surface, and to reject photons scattered from thin clouds and aerosols in the path. Previously we had constructed breadboard versions of our CO2 and O2 sensors, using tunable diode lasers, fiber laser amplifiers and 20 cm diameter telescopes. We have used them to make measurements of gas absorptions over 0.2, 0.4 and 1.3 km long outdoor paths. We also have also calculated several characteristics of the technique for space and have performed an initial space mission accommodation study. During 2008 we reconfigured our lidar for airborne use and made measurements of atmospheric CO2 absorption in the nadir column from the aircraft to the surface during 5 flights. The airborne lidar sweeps the laser wavelength across the CO2 line in either 10 or 20 steps per measurement. The line scan rate is ~ 1 KHz and the laser pulse widths are 1 usec. The time resolved laser backscatter is collected by the telescope and detected by a photomultiplier and recorded by a photon counting timing system. We installed our lidar on the NASA Glenn Lear-25 aircraft in October and first made measurements using the 1571.4 nm CO2 absorption line while flying in northern Ohio. We made laser backscatter and absorption measurements over a variety of land surface types, water surfaces and through thin clouds, broken clouds and to cloud tops. Strong laser signals were observed at altitudes from 2.5 to 11 km on two flights. We completed three additional flights during December 2008 and gathered over 6 hours of atmospheric CO2 column measurements using the 1572.02 and 1572.33 nm CO2 lines. Airborne CO2 line shape and absorption measurements were made while flying at 3-11 km altitudes over southwestern Ohio. Subsequently two flights were made from Ponca City OK, just east of the US Department of Energy's (DOE) ARM site. We made 4 hours of airborne measurements in square patterns around the ARM site at altitudes from 3-8 km. The increased CO2 line absorptions at higher altitudes were evident in all flights. The December flights were also coordinated with DOE investigators who flew an in-situ CO2 sensor on a Cessna aircraft inside the CO2 sounder's flight pattern. These yielded two height resolved profiles of CO2 concentrations from 5 km to the surface, which are being analyzed with radiosonde measurements for comparisons. More details of the flights, measurements and their analysis will be described in the presentation.

BESTIA - the next generation ultra-fast CO 2 laser for advanced accelerator research

DOE PAGES

Pogorelsky, Igor V.; Babzien, Markus; Ben-Zvi, Ilan; ...

2015-12-02

Over the last two decades, BNL’s ATF has pioneered the use of high-peak power CO 2 lasers for research in advanced accelerators and radiation sources. In addition, our recent developments in ion acceleration, Compton scattering, and IFELs have further underscored the benefits from expanding the landscape of strong-field laser interactions deeper into the mid-infrared (MIR) range of wavelengths. This extension validates our ongoing efforts in advancing CO 2 laser technology, which we report here. Our next-generation, multi-terawatt, femtosecond CO 2 laser will open new opportunities for studying ultra-relativistic laser interactions with plasma in the MIR spectral domain, including new regimesmore » in the particle acceleration of ions and electrons.« less

Frequency Stabilization of DFB Laser Diodes at 1572 nm for Spaceborne Lidar Measurements of CO2

NASA Technical Reports Server (NTRS)

Numata, Kenji; Chen, Jeffrey R.; Wu, Stewart T.; Abshire, James B.; Krainak, Michael A.

2010-01-01

We report a fiber-based, pulsed laser seeder system that rapidly switches among 6 wavelengths across atmospheric carbon dioxide (CO2) absorption line near 1572.3 nm for measurements of global CO2 mixing ratios to 1-ppmv precision. One master DFB laser diode has been frequency-locked to the CO2 line center using a frequency modulation technique, suppressing its peak-to-peak frequency drifts to 0.3 MHz at 0.8 sec averaging time over 72 hours. Four online DFB laser diodes have been offset-locked to the master laser using phase locked loops, with virtually the same sub-MHz absolute accuracy. The 6 lasers were externally modulated and then combined to produce the measurement pulse train.

Circumcision using CO2 laser: report of 860 cases

NASA Astrophysics Data System (ADS)

Chen, Wen B.; Chen, Zi-Fu; Zhan, Tian-qi; Gao, Xiang-Xun; Huang, Chao

1993-03-01

Eight-hundred-sixty cases of circumcision using CO2 laser are reported. The age of patients ranged from 9 - 65 years, with a mean age of 23.8 years. The technique was simple and can be quickly accomplished by a single operator. After local anesthesia the glans penis was protected by a protector. Then, circumcision was performed with a CO2 laser -- HeNe laser combined machine. There was an HeNe laser aiming system in this machine thus the surgeon had a three-dimensional visible indicator of the incision. The focusing CO2 laser beam was used for cutting the prepuce during the operation. There was almost no operative bleeding. All the patients needed no antibiotic postoperatively. Complications were minimal and satisfactory results were achieved.

Optical Device for Converting a Laser Beam into Two Co-aligned but Oppositely Directed Beams

NASA Technical Reports Server (NTRS)

Jennings, Donald

2013-01-01

Optical systems consisting of a series of optical elements require alignment from the input end to the output end. The optical elements can be mirrors, lenses, sources, detectors, or other devices. Complex optical systems are often difficult to align from end-to-end because the alignment beam must be inserted at one end in order for the beam to traverse the entire optical path to the other end. The ends of the optical train may not be easily accessible to the alignment beam. Typically, when a series of optical elements is to be aligned, an alignment laser beam is inserted into the optical path with a pick-off mirror at one end of the series of elements. But it may be impossible to insert the beam at an end-point. It can be difficult to locate the pick-off mirror at the desired position because there is not enough space, there is no mounting surface, or the location is occupied by a source, detector, or other component. Alternatively, the laser beam might be inserted at an intermediate location (not at an end-point) and sent, first in one direction and then the other, to the opposite ends of the optical system for alignment. However, in this case, alignment must be performed in two directions and extra effort is required to co-align the two beams to make them parallel and coincident, i.e., to follow the same path as an end-to-end beam. An optical device has been developed that accepts a laser beam as input and produces two co-aligned, but counter-propagating beams. In contrast to a conventional alignment laser placed at one end of the optical path, this invention can be placed at a convenient position within the optical train and aligned to send its two beams simultaneously along precisely opposite paths that, taken together, trace out exactly the same path as the conventional alignment laser. This invention allows the user the freedom to choose locations within the optical train for placement of the alignment beam. It is also self-aligned by design and requires almost no adjustment.

Wrinkled 2D Materials: A Versatile Platform for Low-Threshold Stretchable Random Lasers.

PubMed

Hu, Han-Wen; Haider, Golam; Liao, Yu-Ming; Roy, Pradip Kumar; Ravindranath, Rini; Chang, Huan-Tsung; Lu, Cheng-Hsin; Tseng, Chang-Yang; Lin, Tai-Yung; Shih, Wei-Heng; Chen, Yang-Fang

2017-11-01

A stretchable, flexible, and bendable random laser system capable of lasing in a wide range of spectrum will have many potential applications in next- generation technologies, such as visible-spectrum communication, superbright solid-state lighting, biomedical studies, fluorescence, etc. However, producing an appropriate cavity for such a wide spectral range remains a challenge owing to the rigidity of the resonator for the generation of coherent loops. 2D materials with wrinkled structures exhibit superior advantages of high stretchability and a suitable matrix for photon trapping in between the hill and valley geometries compared to their flat counterparts. Here, the intriguing functionalities of wrinkled reduced graphene oxide, single-layer graphene, and few-layer hexagonal boron nitride, respectively, are utilized to design highly stretchable and wearable random laser devices with ultralow threshold. Using methyl-ammonium lead bromide perovskite nanocrystals (PNC) to illustrate the working principle, the lasing threshold is found to be ≈10 µJ cm -2 , about two times less than the lowest value ever reported. In addition to PNC, it is demonstrated that the output lasing wavelength can be tuned using different active materials such as semiconductor quantum dots. Thus, this study is very useful for the future development of high-performance wearable optoelectronic devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Heterodyne frequency measurements on N2O at 5.3 and 9.0 microns

NASA Technical Reports Server (NTRS)

Wells, J. S.; Jennings, D. A.; Hinz, A.; Murray, J. S.; Maki, A. G.

1985-01-01

Heterodyne frequency measurements on the 01(1)1-00(0)0 band of N2O have been made with the use of a tunable-diode laser, CO laser transfer oscillator, and a CO2 laser frequency synthesizer. A beat frequency was measured between a CO laser and tunable-diode laser whose frequency was locked to the peak of N2O absorption features. The frequency of the CO laser was simultaneously determined by neasuring the beat frequency with respect to a reference synthesized from two CO2 lasers. New rovibrational constants are given for the 01(1)1 state of N2O, which are in excellent agreement with previous results, although the band center is 4 MHz higher than in the previous measurements. A table for the line frequencies and their absolute uncertainties is given for the N2O absorption lines in the wave-number region from 1830 to 1920 kaysers. Some additional frequency measurements near the lower-frequency end of the 02(0)0-00(0)0 band have also been made with respect to a C-12)(0-18)2 laser.

Experimental Investigation into Beam-Riding Physics of Lightcraft Engines: Progress Report

NASA Astrophysics Data System (ADS)

Kenoyer, David A.; Myrabo, Leik N.; Notaro, Samuel J.; Bragulla, Paul W.

2010-05-01

A twin Lumonics K922M pulsed TFA CO2 laser system (pulse duration of approximately 200 ns FWHM spike with 1 us tail) was employed to experimentally measure beam-riding behavior of Type ♯200 lightcraft engines, using the Angular Impulse Measurement Device (AIMD). Beam-riding forces and moments were examined along with engine thrust-vectoring behavior, as a function of: a) laser beam angular and lateral offset from the vehicle axis of symmetry; b) laser pulse energy 12 to 36 joules); c) pulse duration (100 ns and 1 μs); and d) engine size (97.7 mm to 161.2 mm). Maximum lateral momentum coupling coefficients (CM) of 135 N-s/MJ were achieved with the K922M laser whereas previous PLVTS laser (420 J, 18 μs duration) results indicated 15-30 N-s/MJ—an improvement of 4.5x to 9x. Maximum axial CM performance with the K922M is li1ely to be 4x to 7x larger than lateral CM values, but must await confirmation in upcoming tests.

Fifteen terawatt picosecond CO2 laser system.

PubMed

Haberberger, D; Tochitsky, S; Joshi, C

2010-08-16

The generation of a record peak-power of 15 TW (45 J, 3 ps) in a single CO(2) laser beam is reported. Using a master oscillator-power amplifier laser system, it is shown that up to 100 J of energy can be extracted in a train of 3 ps laser pulses separated by 18 ps, a characteristic time of the CO(2) molecule. The bandwidth required for amplifying the short injected laser pulse train in a 2.5 atm final CO(2) amplifier is provided by field broadening of the medium at intensities of up to 140 GW/cm(2). The measured saturation energy for 3 ps pulses is 120 mJ/cm(2) which confirms that energy is simultaneously extracted from six rovibrational lines.

Chemical engineering design of CO oxidation catalysts

NASA Technical Reports Server (NTRS)

Herz, Richard K.

1987-01-01

How a chemical reaction engineer would approach the challenge of designing a CO oxidation catalyst for pulsed CO2 lasers is described. CO oxidation catalysts have a long history of application, of course, so it is instructive to first consider the special requirements of the laser application and then to compare them to the characteristics of existing processes which utilize CO oxidation catalysts. All CO2 laser applications require a CO oxidation catalyst with the following characteristics: (1) active at stoichiometric ratios of O2 and CO, (2) no inhibition by CO2 or other components of the laser environment, (3) releases no particulates during vibration or thermal cycling, and (4) long lifetime with a stable activity. In all applications, low consumption of power is desirable, a characteristic especially critical in aerospace applications and, thus, catalyst activity at low temperatures is highly desirable. High power lasers with high pulse repetition rates inherently require circulation of the gas mixture and this forced circulation is available for moving gas past the catalyst. Low repetition rate lasers, however, do not inherently require gas circulation, so a catalyst that did not require such circulation would be favorable from the standpoint of minimum power consumption. Lasers designed for atmospheric penetration of their infrared radiation utilize CO2 formed from rare isotopes of oxygen and this application has the additional constraint that normal abundance oxygen isotopes in the catalyst must not exchange with rare isotopes in the gas mixture.

In vitro analysis of laser meniscectomy.

PubMed

Vangsness, C T; Akl, Y; Nelson, S J; Liaw, L H; Smith, C F; Marshall, G J

1995-01-01

Partial meniscectomies were performed on 32 fresh human meniscal autopsy specimens. The following laser systems were tested: carbon dioxide (CO2), neodymium:yttrium aluminum garnet (Nd:YAG), potassium titanyl phosphate (KTP), holmium:YAG (Ho:YAG), and excimer. Meniscectomies with these lasers were compared with scalpel, mechanical, and electrocautery meniscectomies. Lasers were applied to specimens in and out of normal saline. Routine hematoxylin and eosin and sirius red sections were prepared for each specimen, and the depths of thermal changes were analyzed. Scanning electron microscopy was used to visualize the meniscectomy interface. Among these specimens, the scalpel and mechanical meniscectomies showed the least extension of cellular changes (range, 10-15 nm). The excimer laser caused the least tissue changes of the lasers tested. Tissue changes were less extensive with the pulsed CO2 laser than with the holmium:YAG, neodymium:YAG, and KTP lasers. Scanning electron microscopy showed that use of the scalpel meniscectomy resulted in the smoothest meniscectomy edge, followed by use of the excimer, CO2, holmium:YAG, neodymium:YAG, and KTP lasers. The most surface disruption occurred with electrocautery. Meniscectomies under saline required more energy and took longer in each case, with the holmium:YAG, neodymium:YAG, and CO2 laser cutting the best. Saline meniscectomies showed less thermal change. The CO2 and KTP lasers cut best in air.

A quantitative thermal and thermomechanical analysis for design optimization and robustness assessment of microassembled high power Yb:CaF2 thin-disk Laser

NASA Astrophysics Data System (ADS)

Joly, S.; Lemesre, M.-A.; Levrier, B.; Lyszyk, C.; Plano, B.; Courjaud, A.; Taira, T.; Bechou, L.

2018-09-01

While considerable effort in the field of high power laser research has been dedicated to evolving thin-disk Lasers into the kilowatt range, thermal and residual stress management remain a critical issue and need to be addressed. In this paper, a quantitative thermal and thermomechanical analysis is presented for design optimization and robustness of high power diode pumped thin-disk ytterbium Lasers based on thermal and thermomechanical Finite Element Method (FEM) simulations. In particular, Yb:CaF2 Lasers are examined with respect to the design and selection of the bonding interface material. Results propose the use of a metallic Au80Sn20 hard solder of greater than 20 μm thickness as a superior solution to adhesive bonding for the prevention of Laser crystal failure under high optical pumping power while maintaining sufficient resistance to mechanical strain. Thermal IR characterizations under "safe" CW pumping power validate our predicted FEM Multiphysics models. Finally, an essentially void-free Au80Sn20 soldering process has been demonstrated for the mounting of Yb:CaF2 crystals onto a CuW heat sink. He currently acts as a Full Professor in electronics and physics at the University of Bordeaux. His research field addresses characterization, physical and failure mechanisms modeling and methods for reliability prediction of optoelectronic/photonic micro and nano-assemblied devices (LEDs, laser diodes, fiber laser, optical amplifier, photodetectors, fibered optical module…) for different applications (telecommunications, medical, space...). Research interests focus on Design for Reliability at the early stage of the development of the device including design, fabrication, characterization and aging effects on packaged optoelectronic materials and functions which involves the exploration of the physics of the light-matter interactions as well as the understanding degradation processes. Since 2010 is currently the manager of the "Reliability Assessment of Micro and Nano-assemblied Devices" Research Group (EDMiNA) at IMS Laboratory. He is the author or co-author of more than 180 regular papers and international conferences. He has also chaired different sessions in international conferences and acts as a reviewer of peer-reviewed journals from Elsevier (Microelectronics Reliab., Optics and Laser Technology…), IOP (Optics Letters), IEEE (Photonics Technology Letters, Devices and Materials Reliability, Electron Devices…). He has managed over 20 PhDs grants and post-docs addressing projects focusing both on fundamental aspects as well as applied research with national and European industrial partnerships with over 5M€ of funding. He is involved in several French and European committees acting as reviewer expert for National Research Agency (ANR) and CATRENE/EURIPIDES programs. Since March 2016, he is appointed Visiting Professor at the French-Canadian Joint Lab LN2 - University of Sherbrooke (Qc, Canada) working on packaging and design for reliability of devices and systems for photonic applications.

Pulsed 2-micron Laser Transmitter For Carbon Dioxide Sensing From Space

NASA Astrophysics Data System (ADS)

Singh, U. N.; Yu, J.; Bai, Y.; Petros, M.

2011-12-01

Carbon dioxide (CO2) has been recognized as one of the most important greenhouse gases. It is essential for the study of global warming to accurately measure the CO2 concentration in the atmosphere and continuously record its variation. Studies of the carbon cycle are limited by the tools available to precisely measure CO2 concentrations by remote sensing. Active sensing, using the Integrated Path Differential Absorption (IPDA) approach, permits measurements day and night, at all latitudes and seasons. The development of a high pulse energy 2-μm laser transmitter for high-precision CO2 measurements from space leverages years of NASA investment in solid-state laser technology. Under NASA Laser Risk Reduction Program, funded by Earth Science Technology Office, researchers at NASA Langley Research Center developed an injection seeded, high repetition rate, Q-switched Ho:YLF laser transmitter for CO2 Differential Absorption Lidar/IPDA (profile/column) measurements from ground and airborne platforms. This master-slave laser system has high optical-to-optical efficiency and seeding success rate. NASA LaRC's 2-micron pulsed laser transmitter possesses advantages over current passive and CW active sensors. First, the pulsed format provides a built-in means for determining range to the scattering target and effectively filtering out the scattering from thin clouds and aerosols, thus eliminating a source of measurement bias. Second, by concentrating the laser energy into a pulse, sufficient backscatter signal strength can be obtained from aerosol scattering rather than relying on a hard target at a known distance. Third, the absorption line at the 2.05 μm band is ideally suited for the CO2 concentration measurement. In particular, the weighting function of 2 μm is optimum for measurement in the lower troposphere where the sources and sinks of CO2 are located. The planned laser transmitter development will lead to a Tm:Fiber pumped Ho:YLF laser transmitter capable of delivering 65 mJ at 50 Hz at on-line wavelength and 50 mJ at 50 Hz at off-line wavelength. The planned laser technology development and performance capabilities are a major step forward in the laser transmitter requirements called out in recent comprehensive system studies, e.g., the European Space Agency (ESA) exploration mission studies, A-SCOPE, for future CO2 column density measurements from space. The planned laser technology development is relevant to NASA's earth science priorities, such as NASA ASCENDS mission for space-based CO2 column density measurements. This presentation will provide an overview of the current status of laser transmitter development and describe future technology development to meet the transmitter requirement for a space-based column averaged measurement of CO2 concentration.

Frequency tuning characteristics of a Q-switched Co:MgF2 laser

NASA Technical Reports Server (NTRS)

Lovold, S.; Moulton, P. F.; Killinger, D. K.; Menyuk, N.

1985-01-01

A tunable Q-switched Co:MgF2 laser has been developed for atmospheric remote sensing applications. Frequency tuning is provided by a quartz etalon and a specially designed three-element birefringent filter covering the whole gain bandwidth of the Co:MgF2 laser. The laser has good temporal and spectral characteristics, with an emission linewidth of approximately 3 GHz (0.1 per cm).

Carbon analysis for inspecting carbonation of concrete using a TEA CO2 laser-induced plasma.

PubMed

Kagawa, Kiichiro; Idris, Nasrullah; Wada, Munehide; Kurniawan, Hendrik; Tsuyuki, Kenichiro; Miura, Satoru

2004-08-01

It has been demonstrated that a spectrochemical analysis of carbon using the laser plasma method can be successfully applied to inspect the carbonation of concrete by detecting carbon produced in aged concrete by a chemical reaction of Ca(OH)2 with CO2 gas in environmental air, turning into CaCO3, which induces degradation of the quality of building concrete. A comparative study has been made using a TEA CO2 laser (500-1000 mJ) and a Q-switched Nd-YAG laser (50-200 mJ) to search for the optimum conditions for carbon analysis, proving the advantage of the TEA CO2 laser for this purpose. Also, it was clarified that laser irradiation with suitable defocusing conditions is a crucial point for obtaining high sensitivity in the detection of carbon. Practical experiments on the inspection of carbonation were carried out using both a concrete sample that had been intentionally carbonated by exposure to high concentrations of CO2 gas and a naturally carbonated concrete sample. As a result, good coincidence was observed between the laser method and the ordinary method, which uses the chemical indicator phenolphthalein, implying that this laser technique is applicable as an in situ quantitative method of inspection for carbonation of concrete.

LASER BIOLOGY AND MEDICINE: Laser analysis of the 13C/12C isotope ratio in CO2 in exhaled air

NASA Astrophysics Data System (ADS)

Stepanov, E. V.

2002-11-01

Tunable diode lasers (TDLs) are applied to the diagnostics of gastroenterological diseases using respiratory tests and preparations enriched with the stable 13C isotope. This method of the analysis of the 13C/12C isotope ratio in CO2 in exhaled air is based on the selective measurement of the resonance absorption at the vibrational — rotational structure of 12CO2 and 13CO2. The CO2 transmission spectra in the region of 4.35 μm were measured with a PbEuSe double-heterostructure TDL. The accuracy of carbon isotope ratio measurements in CO2 of exhaled air performed with the TDL was ~0.5%. The data of clinical tests of the developed laser-based analyser are presented.

Efficacy of Punch Elevation Combined with Fractional Carbon Dioxide Laser Resurfacing in Facial Atrophic Acne Scarring: A Randomized Split-face Clinical Study

PubMed Central

Faghihi, Gita; Nouraei, Saeid; Asilian, Ali; Keyvan, Shima; Abtahi-Naeini, Bahareh; Rakhshanpour, Mehrdad; Nilforoushzadeh, Mohammad Ali; Hosseini, Sayed Mohsen

2015-01-01

Background: A number of treatments for reducing the appearance of acne scars are available, but general guidelines for optimizing acne scar treatment do not exist. The aim of this study was to compare the clinical effectiveness and side effects of fractional carbon dioxide (CO2) laser resurfacing combined with punch elevation with fractional CO2 laser resurfacing alone in the treatment of atrophic acne scars. Materials and Methods: Forty-two Iranian subjects (age range 18–55) with Fitzpatrick skin types III to IV and moderate to severe atrophic acne scars on both cheeks received randomized split-face treatments: One side received fractional CO2 laser treatment and the other received one session of punch elevation combined with two sessions of laser fractional CO2 laser treatment, separated by an interval of 1 month. Two dermatologists independently evaluated improvement in acne scars 4 and 16 weeks after the last treatment. Side effects were also recorded after each treatment. Results: The mean ± SD age of patients was 23.4 ± 2.6 years. Clinical improvement of facial acne scarring was assessed by two dermatologists blinded to treatment conditions. No significant difference in evaluation was observed 1 month after treatment (P = 0.56). Their evaluation found that fractional CO2 laser treatment combined with punch elevation had greater efficacy than that with fractional CO2 laser treatment alone, assessed 4 months after treatment (P = 0.02). Among all side effects, coagulated crust formation and pruritus at day 3 after fractional CO2 laser treatment was significant on both treatment sides (P < 0.05). Conclusion: Concurrent use of fractional laser skin resurfacing with punch elevation offers a safe and effective approach for the treatment of acne scarring. PMID:26538695

Experimental Investigation for 100-Joule-class TEA CO2 Laser and Gas Interaction

NASA Astrophysics Data System (ADS)

Dou, Zhiguo; Yao, Honglin; Wang, Jun; Wen, Ming; Wang, Peng; Yang, Jan; Li, Chong

2006-05-01

Impulse coupling coefficient Cm is one of the most important performance parameters in laser propulsion. Cm is the impulse increment of lightcraft that per joule laser beam energy acts on. The TEA CO2 laser, whose single pulse energy is 100-Joule-class and wavelength is 10.6μm, is adopted by experimental research. In experimental environment cabin, the parabolic lightcraft is fixed on impact pendulum. Using Air, N2, He, CO2, N2-He and N2-CO2, different Cm is obtained. Experimental results indicate that Cm of the mixed gas is improved through changing gas component ratio.

Origin of the enhanced exchange bias in polycrystalline-BiFeO3/Co bilayers by X-ray absorption Spectroscopy

NASA Astrophysics Data System (ADS)

Shen, J. D.; Yang, W. B.; Kumar, A.; Zhao, H. H.; Lai, Y. J.; Feng, L. S.; Xu, Q. Y.; Zhang, Y. Q.; Du, J.; Li, Q.

2018-04-01

Polycrystalline-BiFeO3(BFO)/Co bilayers were grown by pulsed laser deposition (PLD) and magnetron sputtering, with fast laser annealing under magnetic field. The enhanced exchange bias (EB) had been found in the BFO/Co bilayers (Appl. Surf. Sci. 367 (2016) 418). In order to reveal the origin of the enhanced EB in the samples, X-ray absorption Spectroscopy (XAS) of Fe 2p, Co 2p and O 1s were performed. The Co 2p XAS indicated the increase of Co oxidation state and the Fe 2p XAS of sample A and B under laser annealing processes showed that crystal field splitting energy decreased and led to the weakening of spin-orbit coupling with the increasing of the laser fluence. It was considered that the appearance of the oxidation state of Co and Fe2+ ions and the existence of the unidirectional anisotropy due to the laser fluence was responsible for the results and also for the enhanced EB.

13CO2/12CO2 ratio analysis in exhaled air by lead-salt tunable diode lasers for noninvasive diagnostics in gastroenterology

NASA Astrophysics Data System (ADS)

Stepanov, Eugene V.; Zyrianov, Pavel V.; Miliaev, Valerii A.; Selivanov, Yurii G.; Chizhevskii, Eugene G.; Os'kina, Svetlana; Ivashkin, Vladimir T.; Nikitina, Elena I.

1999-07-01

An analyzer of 13CO2/12CO2 ratio in exhaled air based on lead-salt tunable diode lasers is presented. High accuracy of the carbon isotope ratio detection in exhaled carbon dioxide was achieved with help of very simple optical schematics. It was based on the use of MBE laser diodes operating in pulse mode and on recording the resonance CO2 absorption at 4.2 micrometers . Special fast acquisition electronics and software were applied for spectral data collection and processing. Developed laser system was tested in a clinical train aimed to assessment eradication efficiency in therapy of gastritis associated with Helicobacter pylori infection. Data on the 13C-urea breath test used for P.pylori detection and obtained with tunable diode lasers in the course of the trail was compared with the results of Mass-Spectroscopy analysis and histology observations. The analyzer can be used also for 13CO2/12CO2 ratio detection in exhalation to perform gastroenterology breath test based on using other compounds labeled with stable isotopes.

CO.sub.2 optically pumped distributed feedback diode laser

DOEpatents

Rockwood, Stephen D.

1980-01-01

A diode laser optically pumped by a CO.sub.2 coherent source. Interference fringes generated by feeding the optical pumping beam against a second beam, periodically alter the reflectivity of the diode medium allowing frequency variation of the output signal by varying the impingent angle of the CO.sub.2 laser beams.

RGB and white-emitting organic lasers on flexible glass.

PubMed

Foucher, C; Guilhabert, B; Kanibolotsky, A L; Skabara, P J; Laurand, N; Dawson, M D

2016-02-08

Two formats of multiwavelength red, green and blue (RGB) laser on mechanically-flexible glass are demonstrated. In both cases, three all-organic, vertically-emitting distributed feedback (DFB) lasers are assembled onto a common ultra-thin glass membrane substrate and fully encapsulated by a thin polymer overlayer and an additional 50 µm-thick glass membrane in order to improve the performance. The first device format has the three DFB lasers sitting next to each other on the glass substrate. The DFB lasers are simultaneously excited by a single overlapping optical pump, emitting spatially separated red, green and blue laser output with individual thresholds of, respectively, 28 µJ/cm(2), 11 µJ/cm(2) and 32 µJ/cm(2) (for 5 ns pump pulses). The second device format has the three DFB lasers, respectively the red, green and blue laser, vertically stacked onto the flexible glass. This device format emits a white laser output for an optical pump fluence above 42 µJ/cm(2).

Life problems of dc and RF-excited low-power CW CO2 waveguide lasers

NASA Technical Reports Server (NTRS)

Hochuli, U. E.; Haldemann, P. R.

1986-01-01

A number of different, RF-excited 3-W CW CO2 waveguide lasers have been built. Four of these lasers, after continuously working for 15,000-30,000 h, still yield about 70 percent of their original power output. The design variations cover N2and CO-bearing gas mixtures, as well as internal- and external-capacitively coupled excitation electrodes. A similar laser survived 50,000 5-min-ON/5-min-OFF cycles without significant mirror damage. It was not possible to find suitable cold cathodes that allow the building of longitudinally dc-excited CW CO2 waveguide lasers that work for such extended periods of time.

On the O2(a1Δ) quenching by vibrationally excited ozone

NASA Astrophysics Data System (ADS)

Azyazov, V. N.; Mikheyev, P. A.; Heaven, M. C.

2010-09-01

The development of a discharge oxygen iodine laser (DOIL) requires efficient production of singlet delta oxygen (O2(a)) in electric discharge. It is important to understand the mechanisms by which O2(a) is quenched in these devices. To gain understanding of this mechanisms quenching of O2(a) in O(3P)/O2/O3/CO2/He/Ar mixtures has been investigated. Oxygen atoms and singlet oxygen molecules were produced by the 248 nm laser photolysis of ozone. The kinetics of O2(a) quenching were followed by observing the 1268 nm fluorescence of the O2 a --> X transition. Fast quenching of O2(a) in the presence of oxygen atoms and molecules was observed. The mechanism of the process has been examined using kinetic models, which indicate that quenching by vibrationally excited ozone is the dominant reaction.

In vivo effect of carbon dioxide laser-skin resurfacing and mechanical abrasion on the skin's microbial flora in an animal model.

PubMed

Manolis, Evangelos N; Tsakris, Athanassios; Kaklamanos, Ioannis; Markogiannakis, Antonios; Siomos, Konstadinos

2006-03-01

Although beam-scanning carbon dioxide (CO2) lasers have provided a highly efficient tool for esthetic skin rejuvenation there has been no comprehensive animal studies looking into microbial skin changes following CO2 laser skin resurfacing. To evaluate the in vivo effects of CO2 laser skin resurfacing in an experimental rat model in comparison with mechanical abrasion on the skin microbial flora. Four separate cutaneous sections of the right dorsal surface of 10 Wistar rats were treated with a CO2 laser, operating at 18 W and delivering a radiant energy of 5.76 J/cm2, while mechanical abrasions of the skin were created on four sections of the left dorsal surface using a scalpel. Samples for culture and biopsies were obtained from the skin surfaces of the rats on day 1 of application of the CO2 laser or mechanical abrasion, as well as 10, 30, and 90 days after the procedure. The presence of four microorganisms (staphylococci, streptococci, diphtheroids, and yeasts) was evaluated as a microbe index for the skin flora, and colony counts were obtained using standard microbiological methods. Skin biopsy specimens, following CO2 laser treatment, initially showed epidermal and papillary dermal necrosis and later a re-epithelization of the epidermis as well as the generation of new collagen on the upper papillary dermis. The reduction in microbial counts on day 1 of the CO2 laser-inflicted wound was statistically significant for staphylococci and diphtheroids compared with the baseline counts (p=.004 and p<.001, respectively), and for staphylococci, diphtheroids, and yeasts compared with the scalpel-inflicted wound on the same day (p=0.029, p<.001, and p=.030, respectively). Skin resurfacing using CO2 lasers considerably reduces microbial counts of most microorganisms in comparison with either normal skin flora or a scalpel-inflicted wound. This might contribute to the positive clinical outcome of laser skin resurfacing.

In vitro evaluation of enamel demineralization after several overlapping CO2 laser applications.

PubMed

Vieira, K A; Steiner-Oliveira, C; Soares, L E S; Rodrigues, L K A; Nobre-dos-Santos, M

2015-02-01

This study aimed to evaluate the effects of repeated CO2 laser applications on the inhibition of enamel demineralization. Sixty-five human dental enamel slabs were randomly assigned to the following groups (n = 13): control (C), one application of the CO2 laser (L1), two applications of the CO2 laser (L2), three applications of the CO2 laser (L3), and four applications of the CO2 laser (L4). Enamel slabs were irradiated by a 10.6-μm CO2 laser operating at 5 J/cm(2). The slabs were subjected to a pH-cycling regimen and then analyzed by FT-Raman spectroscopy, energy-dispersive X-ray fluorescence spectrometry (EDXRF), cross-sectional micro-hardness, and scanning electron microscopy (SEM). Statistical analysis was performed using ANOVA and Tukey tests (p < 0.05). FT-Raman spectroscopy showed a reduced carbonate content for L1, L3, and L4 groups when compared to C (p < 0.05). The EDXRF data showed no statistical differences between the control and irradiated groups for calcium and phosphorus components (p > 0.05). Cross-sectional micro-hardness data showed a statistically significant difference between the control and all irradiated groups (p < 0.05), but no difference was found among the irradiated groups (p > 0.05) up to 30-μm depth. A tendency of lower demineralization occurred in deeper depths for L3 and L4 groups. The SEM results showed that with repeated applications of the CO2 laser, a progressive melting and recrystallization of the enamel surface occurred. Repeated irradiations of dental enamel may enhance the inhibition of enamel demineralization.

The use of CO(2) laser in revision stapes surgery: experimental studies on heat transmission to the vestibule.

PubMed

Szymański, Marcin; Morshed, Kamal; Mills, Robert P

2007-01-01

The aim of the study was to assess the effect of CO(2) laser on stapes prostheses and measure the heat transmission to the vestibule in experiment model. CO(2) laser was applied on two types of prostheses with power settings (2 and 6W; 0.05 s). Transmission of heat to the 'vestibule' was measured using type K thermocouple and DC-80 data logger during application of the laser on prostheses using a training model of temporal bone. Application of the laser on stainless steel prosthesis did not have any effect on the structure of the prosthesis. The use of the laser on the fluoroplastic-wire piston caused melting and produced holes in the piston. Greater temperature rises occurred with stainless steel than with the fluoroplastic-wire piston. Application of CO(2) laser on stainless steel pistons with 6W can produce inner ear trauma. The use of the laser on fluoroplastic-wire piston is not likely to irritate the inner ear.

Pulsed laser facilities operating from UV to IR at the Gas Laser Lab of the Lebedev Institute

NASA Astrophysics Data System (ADS)

Ionin, Andrei; Kholin, Igor; Vasil'Ev, Boris; Zvorykin, Vladimir

2003-05-01

Pulsed laser facilities developed at the Gas Lasers Lab of the Lebedev Physics Institute and their applications for different laser-matter interactions are discussed. The lasers operating from UV to mid-IR spectral region are as follows: e-beam pumped KrF laser (λ= 0.248 μm) with output energy 100 J; e-beam sustained discharge CO2(10.6 μm) and fundamental band CO (5-6 μm) lasers with output energy up to ~1 kJ; overtone CO laser (2.5-4.2 μm) with output energy ~ 50 J and N2O laser (10.9 μm) with output energy of 100 J; optically pumped NH3 laser (11-14 μm). Special attention is paid to an e-beam sustained discharge Ar-Xe laser (1.73 μm ~ 100 J) as a potential candidate for a laser-propulsion facility. The high energy laser facilities are used for interaction of laser radiation with polymer materials, metals, graphite, rocks, etc.

Quantitative measurement of carbon isotopic composition in CO2 gas reservoir by Micro-Laser Raman spectroscopy

NASA Astrophysics Data System (ADS)

Li, Jiajia; Li, Rongxi; Zhao, Bangsheng; Guo, Hui; Zhang, Shuan; Cheng, Jinghua; Wu, Xiaoli

2018-04-01

The use of Micro-Laser Raman spectroscopy technology for quantitatively determining gas carbon isotope composition is presented. In this study, 12CO2 and 13CO2 were mixed with N2 at various molar fraction ratios to obtain Raman quantification factors (F12CO2 and F13CO2), which provide a theoretical basis for calculating the δ13C value. And the corresponding values were 0.523 (0 < C12CO2/CN2 < 2) and 1.11998 (0 < C13CO2/CN2 < 1.5) respectively. It has shown that the representative Raman peak area can be used for the determination of δ13C values within the relative errors range of 0.076% to 1.154% in 13CO2/12CO2 binary mixtures when F12CO2/F13CO2 is 0.466972625. In addition, measurement of δ13C values by Micro-Laser Raman analysis were carried out on natural CO2 gas from Shengli Oil-field at room temperature under different pressures. The δ13C values obtained by Micro-Laser Raman spectroscopy technology and Isotope Ratio Mass Spectrometry (IRMS) technology are in good agreement with each other, and the relative errors range of δ13C values is 1.232%-6.964%. This research provides a fundamental analysis tool for determining gas carbon isotope composition (δ13C values) quantitatively by using Micro-Laser Raman spectroscopy. Experiment of results demonstrates that this method has the potential for obtaining δ13C values in natural CO2 gas reservoirs.

Antiosteoclastogenesis activity of a CO2 laser antagonizing receptor activator for nuclear factor kappaB ligand-induced osteoclast differentiation of murine macrophages

NASA Astrophysics Data System (ADS)

Kuo, Chun-Liang; Kao, Chia-Tze; Fang, Hsin-Yuan; Huang, Tsui-Hsien; Chen, Yi-Wen; Shie, Ming-You

2015-03-01

Macrophage cells are the important effector cells in the immune reaction which are indispensable for osteoclastogenesis; their heterogeneity and plasticity renders macrophages a primer target for immune system modulation. In recent years, there have been very few studies about the effects of macrophage cells on laser treatment-regulated osteoclastogenesis. In this study, RAW 264.7 macrophage cells were treated with RANKL to regulate osteoclastogenesis. We used a CO2 laser as a model biostimulation to investigate the role of osteoclastogenic. We also evaluated cell viability, cell death and cathepsin K expression. The CO2 laser inhibited a receptor activator of the NF-ĸB ligand (RANKL)-induced formation of osteoclasts during the osteoclast differentiation process. It was also found that irradiation for two times reduced RANKL-enhanced TRAP activity in a dose-dependent manner. Furthermore, CO2 laser-treatment diminished the expression and secretion of cathepsin K elevated by RANKL and was concurrent with the inhibition of TRAF6 induction and NF-ĸB activation. The current report demonstrates that CO2 laser abrogated RANKL-induced osteoclastogenesis by retarding osteoclast differentiation. The CO2 laser can modulate every cell through dose-dependent in vitro RANKL-mediated osteoclastogenesis, such as the proliferation and fusion of preosteoclasts and the maturation of osteoclasts. Therefore, the current results serve as an improved explanation of the cellular roles of macrophage cell populations in osteoclastogenesis as well as in alveolar bone remodeling by CO2 laser-treatment.

CO2 laser myringotomy with a hand-held otoscope and fiber optic delivery system: animal experimentation and preclinical trials

NASA Astrophysics Data System (ADS)

DeRowe, Ari; Ophir, Dov; Finkelstein, Y.; Katzir, Abraham

1993-07-01

CO2 laser myringotomy has previously been proven effective in patients with serous otitis media for short term aeration of the middle ear. However, the system based on a microscope and a coaxially aligned laser is cumbersome and expensive. Also, conventional optical fibers do not transmit CO2 laser energy ((lambda) equals 10.6 micrometers ). We have developed a silver halide optical fiber of diameter 0.9 mm and lengths of several meters, with high transmission at 10.6 micrometers . Using a hand held otoscope coupled to a fiberoptic delivery system CO2 laser myringotomies were performed first in guinea pigs and then in humans. In the animal model the feasibility of the procedure was proven. Different irradiation parameters were studied and a `dose dependent' relationship was found between the total energy used and the duration of a patent myringotomy. This system was used to perform CO2 laser myringotomies under local anesthesia in five patients with serous otitis media and conductive hearing loss. None of the patients complained of discomfort and no scarring was noted. All patients had subjective and audiometric documentation of hearing improvement. The average duration of a patent myringotomy was 21 days. In two patients the effusion recurred. CO2 laser myringotomy utilizing a hand held otoscope coupled to an optical fiber capable of transmitting CO2 laser energy may prove simple and effective in the treatment of serous otitis media.

Effect of CO2, Nd:YAG and Er:YAG Lasers on Microtensile Bond Strength of Composite to Bleached-Enamel.

PubMed

Basir, Mahshid Mohammadi; Rezvani, Mohammad Bagher; Chiniforush, Nasim; Moradi, Zohreh

2016-01-01

Tooth restoration immediately after bleaching is challenging due to the potential problems in achieving adequate bond strength. The aim of this study was to evaluate the effect of surface treatment with ER:YAG, ND:YAG, CO2 lasers and 10% sodium ascorbate solution on immediate microtensile bond strength of composite resin to recently bleached enamel. Ninety sound molar teeth were randomly divided into three main groups (n:30) : NB (without bleaching), HB (bleached with 38% carbamide peroxide) and OB (bleached with Heydent bleaching gel assisted by diode laser). Each group was divided into five subgroups (n:6) : Si (without surface treatment), Er (Er:YAG laser), CO2 (CO2 laser), Nd (Nd:YAG laser) and As (Immersion in 10% sodium ascorbate solution). The bonding system was then applied and composite build-ups were constructed. The teeth were sectioned by low speed saw to obtain enamel- resin sticks and submitted to microtensile bond testing. Statistical analyses were done using two- way ANOVA, Tukey and Tamhane tests. µTBS of bleached teeth irradiated with ND:YAG laser was not significantly different from NB-Nd group. Microtensile bond strength of OB-Er group was higher than NB-Er and HB-Er groups. The mean µTBS of HB-CO2 group was higher than NB-CO2 group; the average µTBS of HB-As and OB-As groups was also higher than NB-As group. Use of Nd:YAG, CO2 lasers and 10% sodium ascorbate solution could improve the bond strength in home-bleached specimens. Application of ND:YAG laser on nonbleached specimens and Er:YAG laser on office-bleached specimens led to the highest µTBS in comparison to other surface treatments in each main group.

ARTICLES: Stabilization of the composition of the gaseous medium in a pulse-periodic CO2 laser by hopcalite

NASA Astrophysics Data System (ADS)

Baranov, V. Yu; Drokov, G. F.; Kuz'menko, V. A.; Mezhevov, V. S.; Pigul'skaya, V. V.

1986-05-01

The results of experiments on using hopcalite to stabilize the gas mixture composition in pulse-periodic and single-pulse CO2 lasers are reported. A study was made of the reasons for a fall in the activity of the catalyst with time under typical CO2 laser conditions and a catalyst regeneration regime was selected. The use of hopcalite ensured prolonged operation of a high-power pulse-periodic CO2 laser without replenishment of the gas mixture in a closed loop. Certain characteristic features concerning the use of hopcalite are described.

Evaluation and comparison of the marginal adaptation of two different substructure materials.

PubMed

Karaman, Tahir; Ulku, Sabiha Zelal; Zengingul, Ali Ihsan; Guven, Sedat; Eratilla, Veysel; Sumer, Ebru

2015-06-01

In this study, we aimed to evaluate the amount of marginal gap with two different substructure materials using identical margin preparations. Twenty stainless steel models with a chamfer were prepared with a CNC device. Marginal gap measurements of the galvano copings on these stainless steel models and Co-Cr copings obtained by a laser-sintering method were made with a stereomicroscope device before and after the cementation process and surface properties were evaluated by scanning electron microscopy (SEM). A dependent t-test was used to compare the mean of the two groups for normally distributed data, and two-way variance analysis was used for more than two data sets. Pearson's correlation analysis was also performed to assess relationships between variables. According to the results obtained, the marginal gap in the galvano copings before cementation was measured as, on average, 24.47 ± 5.82 µm before and 35.11 ± 6.52 µm after cementation; in the laser-sintered Co-Cr structure, it was, on average, 60.45 ± 8.87 µm before and 69.33 ± 9.03 µm after cementation. A highly significant difference (P<.001) was found in marginal gap measurements of galvano copings and a significant difference (P<.05) was found in marginal gap measurements of the laser-sintered Co-Cr copings. According to the SEM examination, surface properties of laser sintered Co-Cr copings showed rougher structure than galvano copings. The galvano copings showed a very smooth surface. Marginal gaps values of both groups before and after cementation were within the clinically acceptable level. The smallest marginal gaps occurred with the use of galvano copings.

Evaluation and comparison of the marginal adaptation of two different substructure materials

PubMed Central

Karaman, Tahir; Ulku, Sabiha Zelal; Zengingul, Ali Ihsan; Eratilla, Veysel; Sumer, Ebru

2015-01-01

PURPOSE In this study, we aimed to evaluate the amount of marginal gap with two different substructure materials using identical margin preparations. MATERIALS AND METHODS Twenty stainless steel models with a chamfer were prepared with a CNC device. Marginal gap measurements of the galvano copings on these stainless steel models and Co-Cr copings obtained by a laser-sintering method were made with a stereomicroscope device before and after the cementation process and surface properties were evaluated by scanning electron microscopy (SEM). A dependent t-test was used to compare the mean of the two groups for normally distributed data, and two-way variance analysis was used for more than two data sets. Pearson's correlation analysis was also performed to assess relationships between variables. RESULTS According to the results obtained, the marginal gap in the galvano copings before cementation was measured as, on average, 24.47 ± 5.82 µm before and 35.11 ± 6.52 µm after cementation; in the laser-sintered Co-Cr structure, it was, on average, 60.45 ± 8.87 µm before and 69.33 ± 9.03 µm after cementation. A highly significant difference (P<.001) was found in marginal gap measurements of galvano copings and a significant difference (P<.05) was found in marginal gap measurements of the laser-sintered Co-Cr copings. According to the SEM examination, surface properties of laser sintered Co-Cr copings showed rougher structure than galvano copings. The galvano copings showed a very smooth surface. CONCLUSION Marginal gaps values of both groups before and after cementation were within the clinically acceptable level. The smallest marginal gaps occurred with the use of galvano copings. PMID:26140178

Effect of Nd:YAG and CO2 Laser Irradiation on Prevention of Enamel Demineralization in Orthodontics: In Vitro Study.

PubMed

Paulos, Renato Siva; Seino, Priscila Yumi; Fukushima, Karen Akemi; Marques, Marcia Martins; de Almeida, Fernanda Campos Sousa; Ramalho, Karen Muller; de Freitas, Patricia Moreira; Brugnera, Aldo; Moreira, Maria Stella

2017-05-01

The aim of this study was to investigate Nd:YAG and CO 2 laser effects in the prevention of demineralization in deeper layers of enamel via successive acid challenge cycles. Lasers are promising in the prevention of enamel demineralization around the orthodontic brackets; however, there are very few studies that evaluate if the effects of treatment could be extended after successive acid challenge cycles due to permanent enamel structural alterations. Human enamel samples were divided into five groups (n = 12): G1-application of 1.23% acidulated fluoride phosphate gel (AFP, control); G2-Nd:YAG laser irradiation (0.6 W, 84.9 J/cm 2 , 10 Hz, 110 μs, contact mode); G3-Nd:YAG laser irradiation associated with AFP; G4-CO 2 laser irradiation (0.5 W, 28.6 J/cm 2 , 50 Hz, 5 μs, and 10 mm focal distance); and G5-CO 2 laser irradiation associated with AFP. The samples were submitted to successive acid challenge cycles. Quantitative light-induced fluorescence and scanning electron microscopy were used to assess enamel demineralization. The data were statistically compared (α = 5%). G1: 50.87 ± 4.57; G2: 47.72 ± 2.87; G3: 50.96 ± 4.01; G4: 28.21 ± 2.19; and G5: 30.13 ± 6.38. The CO 2 laser groups had significantly lower mineral losses than those observed in all other groups after successive acid challenge cycles. Only the CO 2 laser (10.6 μm) irradiation prevents enamel demineralization around the orthodontic brackets even after exposure to successive acid challenges. The CO 2 laser at 10.6 μm showed a deeper effect in enamel regarding caries prevention.

Laser-ablated poly(methyl methacrylate) microdevices for sub-microliter DNA amplification suitable for micro-total analysis systems

NASA Astrophysics Data System (ADS)

Lounsbury, Jenny A.; Poe, Brian L.; Do, Michael; Landers, James P.

2012-08-01

Biochemical techniques, such as the polymerase chain reaction (PCR), can take up to 3.5 h for completion using a commercial bench-top instrument, creating a bottleneck in sample preparation processes. PCR has been successfully adapted to microfluidic devices, reducing the time needed to as little as 7-10 min. Recently, a trend in the field is to use alternative substrates, such as poly(methyl methacyrlate) (PMMA), for the fabrication of microfluidic devices. PMMA has several advantages over more expensive substrates including rigidity without fragility, disposability, and it is easy to fabricate, using techniques such as hot embossing or CO2 laser ablation. Here, we report the fabrication of PMMA microdevices to explore their effectiveness for PCR amplification. Several types of PMMA microdevices were fabricated using a CO2 laser ablation system, with two or three PMMA layers of different thicknesses. Bonding of the microdevices was significantly improved through the use of a grid system etched into the device, allowing for trapped air to escape, eliminating leakage. Using infrared thermal cycling, the ramping rates were determined to be dependent on the thickness of the PMMA used in fabrication, allowing for customization of cycling conditions. Further reduction of the thermal mass by isolation of the chambers provided a significant increase in the heating and cooling rates (up to 6.19 (±0.32 °C s-1) and -7.99 (±0.06 °C s-1), respectively). Bubble formation, a chronic problem in microfluidic systems in general and problematic during the heating phase of PCR, was minimized through the use of a biocompatible adhesive/manifold combination to seal the reservoirs. Finally, successful PCR amplification was demonstrated with both a fragment from the β-globin gene and 15 tetra-nucleotide repeat regions with a sex-typing marker in a conventional STR kit with the latter facilitated by the dynamic coating of the fluidic architecture with poly(ethylene glycol) (PEG).

Analysis of incidence of bulla formation after tattoo treatment using the combination of the picosecond Alexandrite laser and fractionated CO2 ablation.

PubMed

Au, Sonoa; Liolios, Ana M; Goldman, Mitchel P

2015-02-01

The picosecond Alexandrite laser has shown increased efficacy in tattoo removal in comparison to Q-switched lasers. However, bulla formation is a well-known and expected side effect of this novel treatment and causes patient discomfort. To analyze the incidence of bulla formation after tattoo treatment using the combination of the picosecond Alexandrite laser and fractionated CO2 ablation. This is a retrospective chart review to determine the incidence of bulla formation after laser tattoo removal in 95 patients who were treated with either with the picosecond Alexandrite laser alone or in combination with fractional CO2 ablation. Twenty-six patients (32%) treated with the picosecond laser alone experienced blistering, whereas none of the patients treated with the combination of the picosecond laser and fractionated CO2 ablation experienced blistering. The difference in incidence of bulla formation between the 2 groups was found to be statistically significant (p < .05). This study shows a significant decrease in bulla formation associated with tattoo treatment when fractionated CO2 ablation is added to the picosecond Alexandrite laser, which is consistent with observations from a previous case series. This is important because decreasing extensive blistering likely results in increased patient satisfaction and willingness to return for future treatments.

Successful Treatment of Rhinophyma With Fractionated Carbon Dioxide (CO2) Laser in an African-American Man: Case Report and Review of Literature of Fractionated CO2 Laser Treatment of Rhinophyma.

PubMed

Kraeva, Ekaterina; Ho, Derek; Jagdeo, Jared

2016-11-01

Rhinophyma, a late complication of rosacea (phymatous subtype), is a chronic, progressive dermatological condition. The classic pre- sentation of rhinophyma is nodular, thickened skin over the distal nose, and is often accompanied by underlying erythema secondary to in ammation. Due to the unpleasant aesthetic and dis guring appearance, rhinophyma may be associated with a signi cant nega- tive psychosocial impact, resulting in decreased patient quality-of-life. Treatment of rhinophyma is challenging as topical and systemic pharmacotherapies have shown limited ef cacy. We present a case of a 39-year-old African-American male with long-standing, mild rhinophyma who was successfully treated with two sessions of fractionated carbon dioxide (CO2) laser. We also review the medical literature on fractionated CO2 laser treatment of rhinophyma. To the best of our knowledge, this is the rst report of successful treat- ment of rhinophyma using fractionated CO2 laser in an African-American man (Fitzpatrick VI). We believe that fractionated CO2 laser may be a safe and ef cacious treatment modality for rhinophyma in skin of color patients (Fitzpatrick IV-VI) and early intervention with fractionated CO2 laser to prevent rhinophyma worsening may yield better results than late intervention. J Drugs Dermatol. 2016;15(11):1465-1468..

Ordered materials for organic electronics and photonics.

PubMed

O'Neill, Mary; Kelly, Stephen M

2011-02-01

We present a critical review of semiconducting/light emitting, liquid crystalline materials and their use in electronic and photonic devices such as transistors, photovoltaics, OLEDs and lasers. We report that annealing from the mesophase improves the order and packing of organic semiconductors to produce state-of-the-art transistors. We discuss theoretical models which predict how charge transport and light emission is affected by the liquid crystalline phase. Organic photovoltaics and OLEDs require optimization of both charge transport and optical properties and we identify the various trade-offs involved for ordered materials. We report the crosslinking of reactive mesogens to give pixellated full-colour OLEDs and distributed bi-layer photovoltaics. We show how the molecular organization inherent to the mesophase can control the polarization of light-emitting devices and the gain in organic, thin-film lasers and can also provide distributed feedback in chiral nematic mirrorless lasers. We update progress on the surface alignment of liquid crystalline semiconductors to obtain monodomain devices without defects or devices with spatially varying properties. Finally the significance of all of these developments is assessed. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bidirectional current triggering in planar devices based on serially connected VO₂ thin films using 965 nm laser diode.

PubMed

Kim, Jihoon; Park, Kyongsoo; Kim, Bong-Jun; Lee, Yong Wook

2016-08-08

By incorporating a 965 nm laser diode, the bidirectional current triggering of up to 30 mA was demonstrated in a two-terminal planar device based on serially connected vanadium dioxide (VO₂) thin films grown by pulsed laser deposition. The bidirectional current triggering was realized by using the focused beams of laser pulses through the photo-thermally induced phase transition of VO₂. The transient responses of laser-triggered currents were also investigated when laser pulses excited the device at a variety of pulse widths and repetition rates of up to 4.0 Hz. A switching contrast between off- and on-state currents was obtained as ~8333, and rising and falling times were measured as ~39 and ~29 ms, respectively, for 50 ms laser pulses.

Fiber optically guided CO2 laser myringotomy through an otoscope: animal experimentation

NASA Astrophysics Data System (ADS)

DeRowe, Ari; Ophir, Dov; Katzir, Abraham

1992-08-01

We have developed an otoscope which contains an optical fiber capable of transmitting CO2 laser energy. Such a hand-held unit may prove useful in the treatment of acute otitis media and otitis media with effusion. We used crystalline fibers (0.9 mm diameter) capable of transmitting CO2 laser energy. Four guinea pigs were anaesthetized. In one ear a laser myringotomy was performed using 7.5 watts for 0.1 seconds. The diameter of the myringotomy was 1.5 mm. In the other ear a similar conventional myringotomy was performed. After three weeks three laser and three conventional myringotomies were closed. On the average conventional myringotomies closed 50% sooner than laser myringotomies. Temporal bones from three guinea pigs were removed and sectioned according to accepted methods. No histological differences were found between ears. This experiment has proven the feasibility of using an otoscope for fiberoptically guided CO2 laser myringotomy.

Development of tunable high pressure CO2 laser for lidar measurements of pollutants and wind velocities, January 1976 to December 1977

NASA Technical Reports Server (NTRS)

Javan, A.

1979-01-01

A tunable multiatmospheric pulsed CO2 laser with emphasis on experimental features and supporting theoretical analyses important to differential absorption lidar and Doppler lidar measurement of pollutants and wind velocities is reported. The energy deposition and the means to produce the uniform high density plasma in the multiatmospheric medium, through UV preionization of an organic seed gas is discussed. Design features of the pulsed CO2 laser are presented. The radiative processes which are operative and prevent the laser from breaking into oscillations in a large number of modes over its broad amplification bandwidth are described. The mode competition for the transient pulsed laser oscillation in a standing wave and traveling wave ring laser configuration is discussed and contrasted with the approach to steady state oscillations. The latter findings are important to transient injection locking for production of a highly stable pulsed CO2 laser output.

Industrial 2-kW TEA CO2 laser for paint stripping of aircraft

NASA Astrophysics Data System (ADS)

Schweizer, Gerhard; Werner, L.

1995-03-01

Paint stripping of aircraft with pulsed laser radiation has several advantages compared to traditional methods of depainting: selective removal of individual layers possible, suitable for sensitive surfaces, workpiece ready for immediate repainting, and considerable reduction of contaminated waste. For paint stripping of large aircraft pulsed lasers with average power of at least 2 kW are required. Amongst the various types of pulsed lasers technical and economical considerations clearly favor TEA CO2 lasers for this application. The first commercially available TEA CO2 laser with an average power in excess of 2 kW, especially designed for depainting, has been developed by Urenco. The key data of this laser are: pulse energy up to 9 J, repetition rate up to 330 Hz, and beam quality: `flat top'.

CO(2) Laser Fascia to Dura Soldering for Pig Dural Defect Reconstruction.

PubMed

Forer, Boaz; Vasileyev, Tamar; Gil, Ziv; Brosh, Tamar; Kariv, Naam; Katzir, Abraham; Fliss, Dan M

2007-02-01

The purposes of this study were to demonstrate that laser soldering is safe and effective for tissue bonding in dural reconstruction and to compare this new reconstruction technique to an established one. A temperature-controlled fiberoptic CO(2) laser system or fibrin glue were used for in vitro dural defect reconstruction in two groups of pigs. The CO(2) laser technique was also used for dural reconstruction in live pigs. The burst pressure of the reconstructed dura by the laser system was significantly higher than that of fibrin glue (mean pressure 258.5 +/- 117.3 cm H(2)O and 76.8 +/- 47.2 cm H(2)O, respectively). There were no postoperative complications and no signs of thermal damage to the dura, fascia, or underlying tissue on histological analysis following the in vivo CO(2) laser experiments. Temperature-controlled laser soldering is an effective technique for dural repair. It creates a strong tissue bonding with no thermal damage to the tissue. The burst pressure of the reconstructed dura done with laser soldering is significantly higher than that of fibrin glue.

Effect of the CO2 laser (9.6μm) on the dental pulp in humans

NASA Astrophysics Data System (ADS)

Wigdor, Harvey A.; Walsh, Joseph T., Jr.; Mostafi, Reza

2000-03-01

There has been great interest in the potential use of a laser to replace the dental handpiece (drill). Ideally a laser emitting radiation that is absorbed strongly by both the water and hydroxyapatite in teeth, would be a more efficient laser. Previous investigators showed that the 9.3 and 9.6 micron wavelength bands of the CO2 laser contain hydroxyapatite absorption peaks. For this study, human patients who were to have teeth removed for either orthodontic or periodontal reasons were used. A total of 16 teeth were irradiated. The number of teeth treated per patient varied from 1 - 4. The laser used was a prototype CO2 laser (ESC Medical Systems, Yokneam, Israel). The CO2 laser emits 50 mJ 60 microsecond-long pulses of 9.6 micrometer radiation in a beam focused to a 300 micrometer diameter (i/e2) spot. The pulps in both the laser and handpiece prepared holes appeared similar and had no apparent inflammation or vascular changes. It appears from this small sample of laser treated human teeth that this laser has an equal effect to the dental pulpal tissue when compared to the dental handpiece.

Laser Sounder for Global Measurement of CO2 Concentrations in the Troposphere from Space

NASA Technical Reports Server (NTRS)

Abshire, James B.; Riris, Haris; Kawa, S. Randy; Sun, Xiaoli; Chen, Jeffrey; Stephen, Mark A.; Collatz, G. James; Mao, Jianping; Allan, Graham

2007-01-01

Measurements of tropospheric CO2 abundance with global-coverage, a few hundred km spatial and monthly temporal resolution are needed to quantify processes that regulate CO2 storage by the land and oceans. The Orbiting Carbon Observatory (OCO) is the first space mission focused on atmospheric CO2 for measuring total column CO, and O2 by detecting the spectral absorption in reflected sunlight. The OCO mission is an essential step, and will yield important new information about atmospheric CO2 distributions. However there are unavoidable limitations imposed by its measurement approach. These include best accuracy only during daytime at moderate to high sun angles, interference by cloud and aerosol scattering, and limited signal from CO2 variability in the lower tropospheric CO2 column. We have been developing a new laser-based technique for the remote measurement of the tropospheric CO2 concentrations from orbit. Our initial goal is to demonstrate a lidar technique and instrument technology that will permit measurements of the CO2 column abundance in the lower troposphere from aircraft. Our final goal is to develop a space instrument and mission approach for active measurements of the CO2 mixing ratio at the 1-2 ppmv level. Our technique is much less sensitive to cloud and atmospheric scattering conditions and would allow continuous measurements of CO2 mixing ratio in the lower troposphere from orbit over land and ocean surfaces during day and night. Our approach is to use the 1570nm CO2 band and a 3-channel laser absorption spectrometer (i.e. lidar used an altimeter mode), which continuously measures at nadir from a near polar circular orbit. The approach directs the narrow co-aligned laser beams from the instrument's lasers toward nadir, and measures the energy of the laser echoes reflected from land and water surfaces. It uses several tunable fiber laser transmitters which allowing measurement of the extinction from a single selected CO2 absorption line in the 1570 nm band. This band is free from interference from other gases and has temperature insensitive absorption lines. During the measurement the lasers are tuned on- and off- a selected CO2 line near 1572 nm and a selected O2 line near 768 nm in the Oxygen A band at kHz rates. The lasers use tunable diode seed lasers followed by fiber amplifiers, and have spectral widths much narrower than the gas absorption lines. The receiver uses a 1-m diameter telescope and photon counting detectors and measures the background light and energies of the laser echoes from the surface. The extinction and column densities for the CO2 and O2 gases are estimated from the ratio of the on and offline surface echo via the differential optical absorption technique. Our technique rapidly alternates between several on-line wavelengths set to the sides of the selected gas absorption lines. It exploits the atmospheric pressure broadening of the lines to weight the measurement sensitivity to the atmospheric column below 5 km. This maximizes sensitivity to CO2 in the boundary layer, where variations caused by surface sources and sinks are largest. Simultaneous measurements of O2 column will use an identical approach with an O2 line. Thee laser frequencies are tunable and have narrow (MHz) line widths. In combination with sensitive photon counting detectors these enables much higher spectral resolution and precision than is possible with passive spectrometer. 1aser backscatter profiles are also measured, which permits identifying measurements made to cloud tops and through aerosol layers. The measurement approach using lasers in common-nadir-zenith path allows retrieving CO2 column mixing ratios in the lower troposphere irrespective of sun angle. Pulsed laser signals, time gated receiver and a narrow receiver field-of-view are used to isolate the surface laser echo signals and to exclude photons scattered from clouds and aerosols. Nonetheless, the optical absorption change due to a change of a few ppO2 is small, <1 % which makes achieving the needed measurement sensitivities and stabilities quite challenging. Measurement SNRs and stabilities of >600:1 are needed to estimate CO2 mixing ratio at the 1-2 ppm level. We have calculated characteristics of the technique and have demonstrated aspects of the laser, detector and receiver approaches in th e laboratory We have also measured O2 in an absorption cell, and made C02 measurements over a 400 m long (one way) horizontal path using a sensor breadboard. We will describe these and more details of our approach in the paper.

Comparison of KTP, Thulium, and CO2 laser in stapedotomy using specialized visualization techniques: thermal effects.

PubMed

Kamalski, Digna M A; Verdaasdonk, Rudolf M; de Boorder, Tjeerd; Vincent, Robert; Trabelzini, Franco; Grolman, Wilko

2014-06-01

High-speed thermal imaging enables visualization of heating of the vestibule during laser-assisted stapedotomy, comparing KTP, CO2, and Thulium laser light. Perforation of the stapes footplate with laser bears the risk of heating of the inner ear fluids. The amount of heating depends on absorption of the laser light and subsequent tissue ablation. The ablation of the footplate is driven by strong water absorption for the CO2 and Thulium laser. For the KTP laser wavelength, ablation is driven by carbonization of the footplate and it might penetrate deep into the inner ear without absorption in water. The thermal effects were visualized in an inner ear model, using two new techniques: (1) high-speed Schlieren imaging shows relative dynamic changes of temperatures up to 2 ms resolution in the perilymph. (2) Thermo imaging provides absolute temperature measurements around the footplate up to 40 ms resolution. The high-speed Schlieren imaging showed minimal heating using the KTP laser. Both CO2 and Thulium laser showed heating below the footplate. Thulium laser wavelength generated heating up to 0.6 mm depth. This was confirmed with thermal imaging, showing a rise of temperature of 4.7 (±3.5) °C for KTP and 9.4 (±6.9) for Thulium in the area of 2 mm below the footplate. For stapedotomy, the Thulium and CO2 laser show more extended thermal effects compared to KTP. High-speed Schlieren imaging and thermal imaging are complimentary techniques to study lasers thermal effects in tissue.

Numerical simulation of temperature at drilling micro-hole on moving CO2 laser irradiated sticking plaster

NASA Astrophysics Data System (ADS)

Rao, Zhiming; He, Zhifang; Du, Jianqiang; Zhang, Xinyou; Ai, Guoping; Zhang, Chunqiang; Wu, Tao

2012-03-01

This paper applied numerical simulation of temperature by using finite element analysis software Ansys to study a model of drilling on sticking plaster. The continuous CO2 laser doing uniform linear motion and doing uniform circular motion irradiated sticking plaster to vaporize. The sticking plaster material was chosen as the thermal conductivity, the heat capacity and the density. For temperatures above 450 °C, sticking plaster would be vaporized. Based on the mathematical model of heat transfer, the process of drilling sticking plaster by laser beams could be simulated by Ansys. The simulation results showed the distribution of the temperature at the surface of the sticking plaster with the time of vaporizing at CO2 laser to do uniform linear motion and to do uniform circular motion. The temperature of sticking plaster CO2 laser to do uniform linear motion was higher than CO2 laser to do uniform circular motion in the same condition.

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 ......

Research on catalysts for long-life closed-cycle CO2 laser oaperation

NASA Technical Reports Server (NTRS)

Sidney, Barry D.; Schryer, David R.; Upchurch, Billy T.; Hess, Robert V.; Wood, George M.

1987-01-01

Long-life, closed-cycle operation of pulsed CO2 lasers requires catalytic CO-O2 recombination both to remove O2, which is formed by discharge-induced CO2 decomposition, and to regenerate CO2. Platinum metal on a tin-oxide substrate (Pt/SnO2) has been found to be an effective catalyst for such recombination in the desired temperature range of 25 to 100 C. This paper presents a description of ongoing research at NASA-Langley on Pt/SnO2 catalyzed CO-O2 recombination. Included are studies with rare-isotope gases since rare-isotope CO2 is desirable as a laser gas for enhanced atmospheric transmission. Results presented include: (1) the effects of various catalyst pretreatment techniques on catalyst efficiency; (2) development of a technique, verified in a 30-hour test, to prevent isotopic scrambling when C(O-18) and (O-18)2 are reacted in the presence of a common-isotope Pt/Sn(O-16)2 catalyst; and (3) development of a mathematical model of a laser discharge prior to catalyst introduction.

Intensity noise properties of a compact laser device based on a miniaturized MOPA system for spectroscopic applications

NASA Astrophysics Data System (ADS)

Baumgärtner, S.; Juhl, S.; Opalevs, D.; Sahm, A.; Hofmann, J.; Leisching, P.; Paschke, K.

2018-02-01

We present a novel compact laser device based on a semiconductor master-oscillator power-amplifier (MOPA) emitting at 772 nm, suitable for quantum optic and spectroscopy. The optical performance of the laser device is characterized. For miniaturized lasers the thermal management is challenging, we therefore perform thermal simulations and measurements. The first demonstrator is emitting more than 3 W optical power with a linewidth below 2lMHz. Using this MOPA design also compact devices for quantum optics (e.g. rubidium atomic clock) and seed lasers for frequency conversion can be realized [1].

Characterization of diamond thin films and related materials

NASA Astrophysics Data System (ADS)

McKindra, Travis Kyle

Thin carbon films including sputtered deposited graphite and CO 2 laser-assisted combustion-flame deposited graphite and diamond thin films were characterized using optical and electron microscopy, X-ray diffraction and micro-Raman spectroscopy. Amorphous carbon thin films were deposited by DC magnetron sputtering using Ar/O2 gases. The film morphology changed with the oxygen content. The deposition rate decreased as the amount of oxygen increased due to oxygen reacting with the growing film. The use of oxygen in the working gas enhanced the crystalline nature of the films. Graphite was deposited on WC substrates by a CO2 laser-assisted O2/C2H2 combustion-flame method. Two distinct microstructural areas were observed; an inner core of dense material surrounded by an outer shell of lamellar-like material. The deposits were crystalline regardless of the laser power and deposition times of a few minutes. Diamond films were deposited by a CO2 laser-assisted O 2/C2H2/C2H4 combustion-flame method with the laser focused parallel to the substrate surface. The laser enhanced diamond growth was most pronounced when deposited with a 10.532 microm CO2 laser wavelength tuned to the CH2-wagging vibrational mode of the C2H4 molecule. Nucleation of diamond thin films deposited with and without using a CO 2 laser-assisted combustion-flame process was investigated. With no laser there was nucleation of a sub-layer of grains followed by irregular grain growth. An untuned laser wavelength yielded nucleation of a sub-layer then columnar grain growth. The 10.532 microm tuned laser wavelength caused growth of columnar grains.

Optical radiation hazards of laser welding processes. Part II: CO2 laser.

PubMed

Rockwell, R J; Moss, C E

1989-08-01

There has been an extensive growth within the last five years in the use of high-powered lasers in various metalworking processes. The two types of lasers used most frequently for laser welding/cutting processes are the Neodymium-yttrium-aluminum-garnet (Nd:YAG) and the carbon dioxide (CO2) systems. When such lasers are operated in an open beam configuration, they are designated as a Class IV laser system. Class IV lasers are high-powered lasers that may present an eye and skin hazard under most common exposure conditions, either directly or when the beam has been diffusely scattered. Significant control measures are required for unenclosed (open beam), Class IV laser systems since workers may be exposed to scattered or reflected beams during the operation, maintenance, and service of these lasers. In addition to ocular and/or skin exposure hazards, such lasers also may present a multitude of nonlaser beam occupational concerns. Radiant energy measurements are reported for both the scattered laser radiation and the plasma-related plume radiations released during typical high-powered CO2 laser-target interactions. In addition, the application of the nominal hazard zone (NHZ) and other control measures also are discussed with special emphasis on Class IV industrial CO2 laser systems.

Histological study on the effects of microablative fractional CO2 laser on atrophic vaginal tissue: an ex vivo study.

PubMed

Salvatore, Stefano; Leone Roberti Maggiore, Umberto; Athanasiou, Stavros; Origoni, Massimo; Candiani, Massimo; Calligaro, Alberto; Zerbinati, Nicola

2015-08-01

Microablative fractional CO2 laser has been proven to determine tissue remodeling with neoformation of collagen and elastic fibers on atrophic skin. The aim of our study is to evaluate the effects of microablative fractional CO2 laser on postmenopausal women with vulvovaginal atrophy using an ex vivo model. This is a prospective ex vivo cohort trial. Consecutive postmenopausal women with vulvovaginal atrophy managed with pelvic organ prolapse surgical operation were enrolled. After fascial plication, the redundant vaginal edge on one side was treated with CO2 laser (SmartXide2; DEKA Laser, Florence, Italy). Five different CO2 laser setup protocols were tested. The contralateral part of the vaginal wall was always used as control. Excessive vagina was trimmed and sent for histological evaluation to compare treated and nontreated tissues. Microscopic and ultrastructural aspects of the collagenic and elastic components of the matrix were studied, and a specific image analysis with computerized morphometry was performed. We also considered the fine cytological aspects of connective tissue proper cells, particularly fibroblasts. During the study period, five women were enrolled, and 10 vaginal specimens were finally retrieved. Four different settings of CO2 laser were compared. Protocols were tested twice each to confirm histological findings. Treatment protocols were compared according to histological findings, particularly in maximal depth and connective changes achieved. All procedures were uneventful for participants. This study shows that microablative fractional CO2 laser can produce a remodeling of vaginal connective tissue without causing damage to surrounding tissue.

The synergistic effects of CO2 laser treatment with calcium silicate cement of antibacterial, osteogenesis and cementogenesis efficacy

NASA Astrophysics Data System (ADS)

Hsu, T.-T.; Kao, C.-T.; Chen, Y.-W.; Huang, T.-H.; Yang, J.-J.; Shie, M.-Y.

2015-05-01

Calcium silicate-based material (CS) has been successfully used in dental clinical applications. Some researches show that the antibacterial effects of CO2 laser irradiation are highly efficient when bacteria are embedded in biofilm, due to a photo-thermal mechanism. The purpose of this study was to confirm the effects of CO2 laser irradiation on CS, with regard to both material characterization and human periodontal ligament cell (hPDLs) viability. CS was irradiated with a dental CO2 laser using directly mounted fiber optics in wound healing mode with a spot area of 0.25 cm2, and then stored in an incubator at 100% relative humidity and 37 °C for 1 d to set. The hPDLs cultured on CS were analyzed, along with their proliferation and odontogenic differentiation behaviors. The results indicate that the CO2 laser irradiation increased the amount of Ca and Si ions released from the CS, and regulated cell behavior. CO2 laser-irradiated CS promoted cementogenic differentiation of hPDLs, with the increased formation of mineralized nodules on the substrate’s surface. It also up-regulated the protein expression of multiple markers of cementogenic and the expression of cementum attachment protein. The current study provides new and important data about the effects of CO2 laser irradiation on CS. Taking cell functions into account, the Si concentration released from CS with laser irradiated may be lower than a critical value, and this information could lead to the development of new regenerative therapies for dentin and periodontal tissue.

A Broadband Infrared Laser Source (2.5-17 μm) for Plasma Diagnostics

NASA Astrophysics Data System (ADS)

Ionin, A. A.; Kinyaevskii, I. O.; Klimachev, Yu. M.; Kozlov, A. Yu.; Kotkov, A. A.

2017-12-01

This paper presents the results of studies aimed at the creation of a hybrid laser system which is composed of a gas lasers and a nonlinear crystal and appreciably broadens and enriches the radiation spectrum of these lasers. A highly efficient conversion (37%) is attained when generating the second harmonic in a ZnGeP2 crystal owing to an increase in the peak power of CO laser radiation in the mode locking regime. The two-cascade conversion (generation of both sum and difference frequencies) of radiation of a broadband CO laser in the single sample of such nonlinear crystals as ZnGeP2 and AgGaSe2 is demonstrated. In this case, the radiation spectrum is broadened by nearly a factor of two, and the number of detected spectral lines grows by a factor of four. The use of a comparatively simple laser system of gas-discharge CO and CO2 lasers to conversion in AgGaSe2 results in laser radiation tunable over a set of narrow spectral lines within a range from 2.5 to 16.6 μm (more than two and a half octaves).

Deep-Ultraviolet Hyperbolic Metacavity Laser.

PubMed

Shen, Kun-Ching; Ku, Chen-Ta; Hsieh, Chiieh; Kuo, Hao-Chung; Cheng, Yuh-Jen; Tsai, Din Ping

2018-05-01

Given the high demand for miniaturized optoelectronic circuits, plasmonic devices with the capability of generating coherent radiation at deep subwavelength scales have attracted great interest for diverse applications such as nanoantennas, single photon sources, and nanosensors. However, the design of such lasing devices remains a challenging issue because of the long structure requirements for producing strong radiation feedback. Here, a plasmonic laser made by using a nanoscale hyperbolic metamaterial cube, called hyperbolic metacavity, on a multiple quantum-well (MQW), deep-ultraviolet emitter is presented. The specifically designed metacavity merges plasmon resonant modes within the cube and provides a unique resonant radiation feedback to the MQW. This unique plasmon field allows the dipoles of the MQW with various orientations into radiative emission, achieving enhancement of spontaneous emission rate by a factor of 33 and of quantum efficiency by a factor of 2.5, which is beneficial for coherent laser action. The hyperbolic metacavity laser shows a clear clamping of spontaneous emission above the threshold, which demonstrates a near complete radiation coupling of the MQW with the metacavity. This approach shown here can greatly simplify the requirements of plasmonic nanolaser with a long plasmonic structure, and the metacavity effect can be extended to many other material systems. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of Nd:YAG and CO2 lasers on cerebral microvasculature. Study in normal rabbit brain.

PubMed

Kuroiwa, T; Tsuyumu, M; Takei, H; Inaba, Y

1986-01-01

The effect of Nd:YAG and CO2 laser beams on cerebral microvasculature was examined in experimental animals. Soft x-ray microangiography and histological examination of the brain after Nd:YAG laser exposure revealed broad avascular or oligovascular zones in the irradiated and the surrounding edematous tissue, in which the surviving vessels were narrowed and tapered without significant leakage of blood. After CO2 laser exposure, a wedge-shaped tissue defect surrounded by layers of charring, coagulation, and edema was observed. The main finding in the surrounding coagulation and edematous layers was dilatation of the vessels. Hemorrhage was sometimes observed, mainly in the edematous layer. These findings seem to explain the effective hemostatic capability of the Nd:YAG laser and the occasional hemorrhage following CO2 laser exposure, especially at high energy output.

The TELEC - A plasma type of direct energy converter. [Thermo-Electronic Laser Energy Converter for electric power generation

NASA Technical Reports Server (NTRS)

Britt, E. J.

1978-01-01

The Thermo-Electronic Laser Energy Converter (TELEC) is a high-power density plasma device designed to convert a 10.6-micron CO2 laser beam into electric power. Electromagnetic radiation is absorbed in plasma electrons, creating a high-electron temperature. Energetic electrons diffuse from the plasma and strike two electrodes having different areas. The larger electrode collects more electrons and there is a net transport of current. An electromagnetic field is generated in the external circuit. A computer program has been designed to analyze TELEC performance allowing parametric variation for optimization. Values are presented for TELEC performance as a function of cesium pressure and for current density and efficiency as a function of output voltage. Efficiency is shown to increase with pressure, reaching a maximum over 45%.

[Experimental investigations of CO2 laser application in middle ear ossicles].

PubMed

Dazert, S; Russ, D; Mlynski, R; Brors, D; Greiner, A; Aletsee, C; Helms, J

2003-07-01

During the last few years, several laser systems have been applied for procedures in middle ear surgery. In this study, we determined the technical parameters for the dissection of the middle ear ossicles with the CO(2) laser and analyzed the histological findings. The malleus necks of 16 human temporal bones were dissected under standardized conditions using a CO(2) laser with a power output between 35 and 55 kW/cm(2). The specimens were fixed and histological probes of 50- micro m thickness were prepared. The laser outputs led to crater diameters from 0.14 to 0.55 mm. As an analogy between laser energy and thermal tissue destruction, three zones of thermal damage were differentiated: a cinder zone, a carbonization zone, and a zone of dehydration. The metrical dimensions of these zones did not show any correlation to the applied laser energy. The data of this study show that commercially available CO(2) lasers are sufficient for a safe and effective partial resection of middle ear ossicles using a power output of 35 kW/cm(2).

Femtosecond laser excitation of multiple spin waves and composition dependence of Gilbert damping in full-Heusler Co{sub 2}Fe{sub 1−x}Mn{sub x}Al films

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

Cheng, Chuyuan; Li, Shufa; Lai, Tianshu, E-mail: stslts@mail.sysu.edu.cn, E-mail: jhzhao@red.semi.ac.cn

2013-12-02

Spin-wave dynamics in 30 nm thick Co{sub 2}Fe{sub 1−x}Mn{sub x}Al full-Heusler films is investigated using time-resolved magneto-optical polar Kerr spectroscopy under an external field perpendicular to films. Damon-Eshbach (DE) and the first-order perpendicular standing spin-wave (PSSW) modes are observed simultaneously in four samples with x = 0, 0.3, 0.7, and 1. The frequency of DE and PSSW modes does not apparently depend on composition x, but damping of DE mode significantly on x and reaches the minimum as x = 0.7. The efficient coherent excitation of DE spin wave exhibits the promising application of Co{sub 2}Fe{sub 0.3}Mn{sub 0.7}Al films in magnonic devices.

Pulsed Airborne Lidar Measurements of Atmospheric CO2 Column Absorption and Line Shapes from 3-13 km Altitudes

NASA Technical Reports Server (NTRS)

Abshire, James; Riris, Haris; Allan, Graham; Weaver, Clark; Mao, Jianping; Sun, Xiaoli; Hasselbrack, William

2010-01-01

We have developed a pulsed lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's planned ASCENDS space mission. Our technique uses two pulsed laser transmitters allowing simultaneous measurement of a CO2 absorption line in the 1570 nm band, O2 extinction in the Oxygen A-band and surface height and backscatter. The lidar measures the energy and time of flight of the laser echoes reflected from the atmosphere and surface. The lasers are rapidly and precisely stepped in wavelength across the CO2 line and an O2 line region during the measurement. The direct detection receiver uses a telescope and photon counting detectors, and measures the background light and energies of the laser echoes from the surface along with scattering from any aerosols in the path. The gas extinction and column densities for the CO2 and O2 gases are estimated from the ratio of the on- and off- line signals via the DIAL technique. Time gating is used to isolate the laser echo signals from the surface, and to reject laser photons scattered in the atmosphere. The time of flight of the laser pulses are also used to estimate the height of the scattering surface and to identify cases of mixed cloud and ground scattering. We have developed an airborne lidar to demonstrate the CO2 measurement from the NASA Glenn Lear-25 aircraft. The airborne lidar steps the pulsed laser's wavelength across the selected CO2 line with 20 steps per scan. The line scan rate is 450 Hz, the laser pulse widths are 1 usec, and laser pulse energy is 24 uJ. The time resolved laser backscatter is collected by a 20 cm telescope, detected by a photomultiplier and is recorded by a photon counting system. We made initial airborne measurements on flights during fall 2008. Laser backscatter and absorption measurements were made over a variety of land and water surfaces and through thin clouds. The atmospheric CO2 column measurements using the 1572.33 nm CO2 lines. Two flights were made above the US Department of Energy's (DOE) SGP ARM site at altitudes from 3-8 km. These flights were coordinated with DOE investigators who flew an in-situ CO2 sensor on a Cessna aircraft under the path. The increasing CO2 line absorptions with altitudes were evident and comparison with in-situ measurements showed agreements to 6 ppm. In spring 2009 we improved the aircraft's nadir window and during July and August we made 9 additional 2 hour long flights and measured the atmospheric CO2 absorption and line shapes using the 1572.33 nm CO2 line. Measurements were made at stepped altitudes from 3-13 km over a variety of surface types in Nebraska, Illinois, the SGP ARM site, and near and over the Chesapeake Bay in North Carolina and eastern Virginia. Strong laser signals and clear CO2 line shapes were observed at all altitudes, and some measurements were made through thin clouds. The flights over the ARM site were underflown with in-situ measurements made from the DOE Cessna. Analysis shows that the average signal levels follow predicted values, the altimetry measurements had an uncertainty of about 4 m, and that the average optical line depths follow the number density calculated from in-situ sensor readings. The Oklahoma and east coast flights were coordinated with a LaRC/ITT CO2 lidar on the LaRC UC-12 aircraft, a LaRC in-situ CO2 sensor, and the Oklahoma flights also included a JPL CO2 lidar on a Twin Otter aircraft. More details of the flights, measurements, analysis and scaling to space will be described in the presentation.

High Efficiency Coupling of Optical Fibres with SU8 Micro-droplet Using Laser Welding Process

NASA Astrophysics Data System (ADS)

Yardi, Seema; Gupta, Ankur; Sundriyal, Poonam; Bhatt, Geeta; Kant, Rishi; Boolchandani, D.; Bhattacharya, Shantanu

2016-09-01

Apart from micro- structure fabrication, ablation, lithography etc., lasers find a lot of utility in various areas like precision joining, device fabrication, local heat delivery for surface texturing and local change of microstructure fabrication of standalone optical micro-devices (like microspheres, micro-prisms, micro-scale ring resonators, optical switches etc). There is a wide utility of such systems in chemical/ biochemical diagnostics and also communications where the standalone optical devices exist at a commercial scale but chip based devices with printed optics are necessary due to coupling issues between printed structures and external optics. This paper demonstrates a novel fabrication strategy used to join standalone optical fibres to microchip based printed optics using a simple SU8 drop. The fabrication process is deployed for fiber to fiber optical coupling and coupling between fiber and printed SU-8 waveguides. A CO2 laser is used to locally heat the coupling made up of SU8 material. Optimization of various dimensional parameters using design of experiments (DOE) on the bonded assembly has been performed as a function of laser power, speed, cycle control, spot size so on so forth. Exclusive optical [RF] modelling has been performed to estimate the transmissibility of the optical fibers bonded to each other on a surface with SU8. Our studies indicate the formation of a Whispering gallery mode (WGM) across the micro-droplet leading to high transmissibility of the signal. Through this work we have thus been able to develop a method of fabrication for optical coupling of standalone fibers or coupling of on-chip optics with off-chip illumination/detection.

Possible stabilization of the frequency of a CO/sub 2/ laser using an external Stark cell containing 1-1 difluoroethane

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

Avtonomov, V.P.; Alexandrescu, R.; Dumitras, D.

1979-02-01

Results are presented of measurements of the Stark modulation index and absorption coefficient of CO/sub 2/ laser radiation due to the P (24) line by 1-1 difluorethane (C/sub 2/H/sub 4/F/sub 2/). The possibility of stabilizing the CO/sub 2/ laser frequency using a Stark cell is demonstrated and the laser frequency tuning efficiency within the P (24) line of the 00/sup 0/1--10/sup 0/0 transition is determined.

TEA CO 2 Laser Simulator: A software tool to predict the output pulse characteristics of TEA CO 2 laser

NASA Astrophysics Data System (ADS)

Abdul Ghani, B.

2005-09-01

"TEA CO 2 Laser Simulator" has been designed to simulate the dynamic emission processes of the TEA CO 2 laser based on the six-temperature model. The program predicts the behavior of the laser output pulse (power, energy, pulse duration, delay time, FWHM, etc.) depending on the physical and geometrical input parameters (pressure ratio of gas mixture, reflecting area of the output mirror, media length, losses, filling and decay factors, etc.). Program summaryTitle of program: TEA_CO2 Catalogue identifier: ADVW Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADVW Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Computer: P.IV DELL PC Setup: Atomic Energy Commission of Syria, Scientific Services Department, Mathematics and Informatics Division Operating system: MS-Windows 9x, 2000, XP Programming language: Delphi 6.0 No. of lines in distributed program, including test data, etc.: 47 315 No. of bytes in distributed program, including test data, etc.:7 681 109 Distribution format:tar.gz Classification: 15 Laser Physics Nature of the physical problem: "TEA CO 2 Laser Simulator" is a program that predicts the behavior of the laser output pulse by studying the effect of the physical and geometrical input parameters on the characteristics of the output laser pulse. The laser active medium consists of a CO 2-N 2-He gas mixture. Method of solution: Six-temperature model, for the dynamics emission of TEA CO 2 laser, has been adapted in order to predict the parameters of laser output pulses. A simulation of the laser electrical pumping was carried out using two approaches; empirical function equation (8) and differential equation (9). Typical running time: The program's running time mainly depends on both integration interval and step; for a 4 μs period of time and 0.001 μs integration step (defaults values used in the program), the running time will be about 4 seconds. Restrictions on the complexity: Using a very small integration step might leads to stop the program run due to the huge number of calculating points and to a small paging file size of the MS-Windows virtual memory. In such case, it is recommended to enlarge the paging file size to the appropriate size, or to use a bigger value of integration step.

Histological changes induced by CO2 laser microprobe specially designed for root canal sterilization: in vivo study.

PubMed

Kesler, G; Koren, R; Kesler, A; Hay, N; Gal, R

1998-10-01

Until now, no suitable delivery fiber has existed for CO2 laser endodontic radiation in the apical region, where it is most difficult to eliminate the pulp tissue using conventional methods. To overcome this problem, we have designed a microprobe that reaches closer to the apex, distributing the energy density to a smaller area of the root canal and thus favorably increasing the thermal effects. A CO2 laser microprobe coupled onto a special hand piece was attached to the delivery fiber of a Sharplan 15-F CO2 laser. The study was conducted on 30 vital maxillary or mandibulary, central, lateral, or premolar teeth destined for extraction due to periodontal problems. Twenty were experimentally treated with pulsed CO2 laser delivered by this newly developed fiber after conventional root canal preparation. Temperature measured at three points on the root surface during laser treatment did not exceed 38 degrees C. Ten teeth represented the control group, in which only root canal preparation was performed in the conventional method. Histological examination of the laser-treated teeth showed coagulation necrosis and vacuolization of the remaining pulp tissue in the root canal periphery. Primary and secondary dentin appeared normal in all cases treated with 15-F CO2 laser. Gram stain and bacteriologic examination revealed complete sterilization. These results demonstrate the unique capabilities of this special microprobe in sterilization of the root canal, with no thermal damage to the surrounding tissue. The combination of classical root canal preparation with CO2 laser irradiation using this special microprobe before closing the canal can drastically change the quality of root canal fillings.

Quantitative measurement of carbon isotopic composition in CO2 gas reservoir by Micro-Laser Raman spectroscopy.

PubMed

Li, Jiajia; Li, Rongxi; Zhao, Bangsheng; Guo, Hui; Zhang, Shuan; Cheng, Jinghua; Wu, Xiaoli

2018-04-15

The use of Micro-Laser Raman spectroscopy technology for quantitatively determining gas carbon isotope composition is presented. In this study, 12 CO 2 and 13 CO 2 were mixed with N 2 at various molar fraction ratios to obtain Raman quantification factors (F 12CO2 and F 13CO2 ), which provide a theoretical basis for calculating the δ 13 C value. And the corresponding values were 0.523 (0

Novel method to sample very high power CO2 lasers: II Continuing Studies

NASA Astrophysics Data System (ADS)

Eric, John; Seibert, Daniel B., II; Green, Lawrence I.

2005-04-01

For the past 28 years, the Laser Hardened Materials Evaluation Laboratory (LHMEL) at the Wright-Patterson Air Force Base, OH, has worked with CO2 lasers capable of producing continuous energy up to 150 kW. These lasers are used in a number of advanced materials processing applications that require accurate spatial energy measurements of the laser. Conventional non-electronic methods are not satisfactory for determining the spatial energy profile. This paper describes continuing efforts in qualifying the new method in which a continuous, real-time electronic spatial energy profile can be obtained for very high power, (VHP) CO2 lasers.

In Situ analysis of CO2 laser irradiation on controlling progression of erosive lesions on dental enamel.

PubMed

Lepri, Taísa Penazzo; Scatolin, Renata Siqueira; Colucci, Vivian; De Alexandria, Adílis Kalina; Maia, Lucianne Cople; Turssi, Cecília Pedroso; Corona, Silmara Aparecida Milori

2014-08-01

The present study aimed to evaluate in situ the effect of CO2 laser irradiation to control the progression of enamel erosive lesions. Fifty-six slabs of bovine incisors enamel (5 × 3 × 2.5 mm(3) ) were divided in four distinct areas: (1) sound (reference area), (2) initial erosion, (3) treatment (irradiated or nonirradiated with CO2 laser), (4) final erosion (after in situ phase). The initial erosive challenge was performed with 1% citric acid (pH = 2.3), for 5 min, 2×/day, for 2 days. The slabs were divided in two groups according to surface treatment: irradiated with CO2 laser (λ = 10.6 µm; 0.5 W) and nonirradiate. After a 2-day lead-in period, 14 volunteers wore an intraoral palatal appliance containing two slabs (irradiated and nonirradiated), in two intraoral phases of 5 days each. Following a cross-over design during the first intraoral phase, half of the volunteers immersed the appliance in 100 mL of citric acid for 5 min, 3×/day, while other half of the volunteers used deionized water (control). The volunteers were crossed over in the second phase. Enamel wear was determined by an optical 3D profilometer. Three-way ANOVA for repeated measures revealed that there was no significant interaction between erosive challenge and CO2 laser irradiation (P = 0.419). Erosive challenge significantly increased enamel wear (P = 0.001), regardless whether or not CO2 laser irradiation was performed. There was no difference in enamel wear between specimens CO2 -laser irradiated and non-irradiated (P = 0.513). Under intraoral conditions, CO2 laser irradiation did not control the progression of erosive lesions in enamel caused by citric acid. © 2014 Wiley Periodicals, Inc.

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

The efficacy and safety of subcision using CO2 gas combined with fractional laser for acne scars: Clinical and microscopic evaluation.

PubMed

Lee, Sang Jun; Suh, Dong Hye; Chang, Ka Yeon; Kim, Hyun Joo; Kim, Tae In; Jeong, Ki-Heon; Shin, Min Kyung; Song, Kye Yong

2016-11-01

Various modalities have been used to treat acne scars. CO 2 fractional laser is an effective and commonly used treatment. CO 2 gas injection into the dermis by needle with high pressure can cause fibrotic collagen breakage, producing the effects of subcision. CO 2 also stimulates collagen synthesis by increasing neovascularization and releasing oxygen. This study evaluated the efficacy and the safety of the combined treatment with CO 2 gas subcision and CO 2 fractional laser for acne scars. Fourteen patients with acne scars were treated with three sessions of CO 2 gas subcision at 2-week intervals and two sessions of fractional laser at 4-week interval. The clinical improvement was assessed using a 4-point scale. For histologic analysis, punch biopsy was performed before and after treatment in 10 patients. All patients experienced clinical improvements. Excellent, marked, moderate, and mild response was achieved in 1 (7%), 8 (57%), 4 (29%), and 1 patient (7%), respectively. Histologic evaluation of the biopsy specimens showed increased dermal collagen with dermal thickening and elastic fiber straightening in the reticular dermis after the treatment. The combination therapy with CO 2 gas subcision and fractional laser was satisfactory and safe for treating acne scars. Abbreviation and acronym: CO 2 : Carbon dioxide GAS: Global assessment scale H&E: hematoxylin and eosin; SD: standard deviation.

Fractional CO2 lasers contribute to the treatment of stable non-segmental vitiligo.

PubMed

Yuan, Jinping; Chen, Hongqiang; Yan, Ru; Cui, Shaoshan; Li, Yuan-Hong; Wu, Yan; Gao, Xing-Hua; Chen, Hong-Duo

2016-12-01

Stable non-segmental vitiligo is often resistant to conventional therapies. The purpose of this study was to investigate the effect of three types of fractional lasers in the treatment of stable non-segmental vitiligo. Twenty patients were enrolled in the study. The vitiligo lesions of each patient were divided into four treatment parts, and all parts were treated with narrowband ultraviolet-B (NB-UVB). Three of the four parts were respectively treated with three types of fractional lasers (two ablative 10,600-nm CO 2 lasers and one non-ablative 1,565-nm laser), followed by topical betamethasone solution application. The treatment period lasted six months. Efficacy and satisfaction were respectively assessed by dermatologists and patients. The ablative CO 2 lasers, in combination with topical betamethasone solution and NB-UVB, achieved marked to excellent improvement on white patches assessed by dermatologists. Patients showed high satisfaction scores for the treatments. The non-ablative 1,565-nm fractional laser did not provide any further benefit in the treatment of vitiligo. No severe adverse events developed for any of the treatments. The treatment protocol with ablative CO 2 lasers, in combination with topical betamethasone solution and NB-UVB, was suitable for stable non-segmental vitiligo. For vitiligo, the ablative fractional CO 2 laser is more effective than the non-ablative fractional laser.

Progress Toward Measuring CO2 Isotopologue Fluxes in situ with the LLNL Miniature, Laser-based CO2 Sensor

NASA Astrophysics Data System (ADS)

Osuna, J. L.; Bora, M.; Bond, T.

2015-12-01

One method to constrain photosynthesis and respiration independently at the ecosystem scale is to measure the fluxes of CO2­ isotopologues. Instrumentation is currently available to makes these measurements but they are generally costly, large, bench-top instruments. Here, we present progress toward developing a laser-based sensor that can be deployed directly to a canopy to passively measure CO2 isotopologue fluxes. In this study, we perform initial proof-of-concept and sensor characterization tests in the laboratory and in the field to demonstrate performance of the Lawrence Livermore National Laboratory (LLNL) tunable diode laser flux sensor. The results shown herein demonstrate measurement of bulk CO2 as a first step toward achieving flux measurements of CO2 isotopologues. The sensor uses a Vertical Cavity Surface Emitting Laser (VCSEL) in the 2012 nm range. The laser is mounted in a multi-pass White Cell. In order to amplify the absorption signal of CO2 in this range we employ wave modulation spectroscopy, introducing an alternating current (AC) bias component where f is the frequency of modulation on the laser drive current in addition to the direct current (DC) emission scanning component. We observed a strong linear relationship (r2 = 0.998 and r2 = 0.978 at all and low CO2 concentrations, respectively) between the 2f signal and the CO2 concentration in the cell across the range of CO2 concentrations relevant for flux measurements. We use this calibration to interpret CO2 concentration of a gas flowing through the White cell in the laboratory and deployed over a grassy field. We will discuss sensor performance in the lab and in situ as well as address steps toward achieving canopy-deployed, passive measurements of CO2 isotopologue fluxes. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-675788

Simultaneous measurements of multiple parameters at elevated temperature using a frequency-division multiplexing scheme with tunable diode lasers.

PubMed

Cai, Tingdong; Gao, Guangzhen; Liu, Ying

2012-10-01

A multiplexed diode-laser sensor system based on second harmonic detection of wavelength modulation spectroscopy (WMS) is developed for application at elevated temperatures with two near-infrared diode lasers multiplexed using a frequency-division multiplexing scheme. One laser is tuned over a H(2)O line pair near 7079.176 and 7079.855 cm(-1), and another laser is tuned over a pair of CO(2) and CO lines near 6361.250 and 6361.344 cm(-1). Temperature and concentrations of H(2)O, CO(2), and CO could be measured simultaneously by this system. In order to remove the need for calibration and correct for transmission variation due to beam steering, mechanical misalignments, soot, and windows fouling, the WMS-1f normalized 2f method is used. Demonstration experiments are conducted in a heated static cell. The precision of temperature and the concentrations for H(2)O, CO(2), and CO are found to be 1.57%, 3.87%, 3.01%, and 3.58%, respectively. These results illustrate the potential of this sensor for applications at high temperatures.

Optimization of discharge circuit of the TEA CO II laser with two discharge channels

NASA Astrophysics Data System (ADS)

Hu, Xiao Yong; Zhang, LiLi; Ren, DeMing; Qu, YanChen; Zhao, WeiJiang; Song, BaoAn

2007-01-01

In order to achieve the highest peak power of radiation pulse and highest output energy, the primary circuit parameters are investigated to optimize the discharge circuit performance of the laser. The structure and the discharge circuit of the laser are discussed at first. To realize synchronous discharge in two discharge channels, the conjunct electrode device for two pairs of discharge electrodes is designed. Finally, the results of the experiments on the primary circuit parameters are given. The discharge is most stable at a pressure of 5.33×10 4Pa when the pressure of gaseous mixture CO II:N II:He=1:1:3 is changed from 2.67×10 4 Pa to 6.67×10 4 Pa. The ratio of storage capacitance to peak capacitance is chosen to be about 1.5-7/3, because residual voltage is lower on this condition and residual voltage is adverse to discharge. When the inductance 330μH is used, the homogeneous glow discharge in a widest voltage range is obtained. The duration of when the stimuli voltage is increased in homogeneous glow discharge condition. The discharge circuit allows charge and discharge and the magnitude of residual voltage decrease the homogeneous glow discharge in a wide range of pressure of gaseous mixture when these circuit parameters are used. Thus it offers reference to the improvement of output characteristic of TEA CO II laser with two discharge channels.

Multiparameter bifurcations and mixed-mode oscillations in Q-switched CO2 lasers.

PubMed

Doedel, Eusebius J; Pando L, Carlos L

2014-05-01

We study the origin of mixed-mode oscillations and related bifurcations in a fully molecular laser model that describes CO2 monomode lasers with a slow saturable absorber. Our study indicates that the presence of isolas of periodic mixed-mode oscillations, as the pump parameter and the cavity-frequency detuning change, is inherent to Q-switched CO2 monomode lasers. We compare this model, known as the dual four-level model, to the more conventional 3:2 model and to a CO2 laser model for fast saturable absorbers. In these models, we find similarities as well as qualitative differences, such as the different nature of the homoclinic tangency to a relevant unstable periodic orbit, where the Gavrilov-Shilnikov theory and its extensions may hold. We also show that there are isolas of periodic mixed-mode oscillations in a model for CO2 lasers with modulated losses, as the pump parameter varies. The coarse-grained bifurcation diagrams of the periodic mixed-mode oscillations in these models suggest that these oscillations belong to similar classes.

CO2 lasers in the management of potentially malignant and malignant oral disorders

PubMed Central

2012-01-01

The CO2 laser was invented in 1963 by Kumar Patel. Since the early 1970s, CO2 laser has proved to be an effective method of treatment for patients with several types of oral lesions, including early squamous cell carcinoma. Laser surgery of oral premalignant disorders is an effective tool in a complete management strategy which includes careful clinical follow-up, patient education to eliminate risk factors, reporting and biopsying of suspicious lesions and any other significant lesions. However, in a number of patients, recurrence and progression to malignancy remains a risk. CO2 laser resection has become the preferred treatment for small oral and oropharyngeal carcinomas. Laser resection does not require reconstructive surgery. There is minimal scarring and thus, optimum functional results can be expected. New and improved applications of laser surgery in the treatment of oral and maxillofacial/head and neck disorders are being explored. As more surgeons become experienced in the use of lasers and as our knowledge of the capabilities and advantages of this tool expands, lasers may play a significant role in the management of different pathologies. PMID:22546534

Thermographic study of laser on arteries.

PubMed

Mnitentag, J; Marques, E F; Ribeiro, M P; Braga, G A; Navarro, M R; Veratti, A B; Armelin, E; Macruz, R; Jatene, A D

1987-01-01

We analyzed the different effects of CO2, Nd-YAG, and argon lasers on aorta by using a Thermovision infrared system that registered the laser interaction with mongrel dog aorta. The images (thermograms) obtained were processed by a computer, which associated each area of the same temperature with a determined color. These thermograms were compared to histological analysis of the respective samples and the following results were obtained: (1) After the application of each laser there is very little propagation of heat in tissue. (2) The CO2 laser makes tissue reach 100 degrees C in less than 0.05 seconds. (3) The heat dissipation time was higher with the Nd-YAG laser due to higher scattering on tissue. Based on this research we conclude that the CO2 laser was best absorbed, the Nd-YAG laser penetrated human tissue with the best results, and the argon laser had the most significant backscattering.

Strong-field physics with mid-infrared lasers

NASA Astrophysics Data System (ADS)

Pogorelsky, I. V.

2002-04-01

Mid-infrared gas laser technology promises to become a unique tool for research in strong-field relativistic physics. The degree to which physics is relativistic is determined by a ponderomotive potential. At a given intensity, a 10 μm wavelength CO2 laser reaches a 100 times higher ponderomotive potential than the 1 μm wavelength solid state lasers. Thus, we can expect a proportional increase in the throughput of such processes as laser acceleration, x-ray production, etc. These arguments have been confirmed in proof-of-principle Thomson scattering and laser acceleration experiments conducted at BNL and UCLA where the first terawatt-class CO2 lasers are in operation. Further more, proposals for the 100 TW, 100 fs CO2 lasers based on frequency-chirped pulse amplification have been conceived. Such lasers can produce physical effects equivalent to a hypothetical multi-petawatt solid state laser. Ultra-fast mid-infrared lasers will open new routes to the next generation electron and ion accelerators, ultra-bright monochromatic femtosecond x-ray and gamma sources, allow to attempt the study of Hawking-Unruh radiation, and explore relativistic aspects of laser-matter interactions. We review the present status and experiments with terawatt-class CO2 lasers, sub-petawatt projects, and prospective applications in strong-field science. .

Current status of lasers in soft tissue dental surgery.

PubMed

Pick, R M; Colvard, M D

1993-07-01

The aims of this paper are to briefly describe laser physics, the types of lasers currently available for use on soft tissues focusing primarily on CO2 and Nd:YAG laser energies, the histological effects of lasers on oral tissues, laser safety, the clinical applications of lasers on oral soft tissues, and future directions. Of the two types of lasers currently available for dental applications, both the CO2 and Nd:YAG lasers can be used for frenectomies, ablation of lesions, incisional and excisional biopsies, gingivectomies, gingivoplasties, soft tissue tuberosity reductions, operculum removal, coagulation of graft donor sites, and certain crown lengthening procedures. The advantages of lasers include a relatively bloodless surgical and post-surgical course, minimal swelling and scarring, coagulation, vaporization, and cutting, minimal or no suturing, reduction in surgical time, and, in a majority of cases, much less or no post-surgical pain. CO2 lasers, compared to Nd:YAG are faster for most procedures, with less depth of tissue penetration and a well-documented history. There have been recent reports on the use of the Nd:YAG laser for periodontal scaling, gingival curettage, and root desensitization, but further research needs to be conducted. Both the CO2 and the Nd:YAG laser have limited use in conventional flap therapy.

Skin Pretreatment With Conventional Non-Fractional Ablative Lasers Promote the Transdermal Delivery of Tranexamic Acid.

PubMed

Hsiao, Chien-Yu; Sung, Hsin-Ching; Hu, Sindy; Huang, Chun-Hsun

2016-07-01

Laser pretreatment of skin can be used to enable drugs used in dermatology to penetrate the skin to the depth necessary for their effect to take place. To compare the permeation of tranexamic acid after conventional non-fractionated ablative Er:YAG and CO2 laser pretreatment in a laser-aided transdermal delivery system. An erbium-doped yttrium aluminium garnet (Er:YAG) and a CO2 laser were used to pretreat dorsal porcine skin. Scanning electron microscopy was used to examine disruption of the skin surface. Confocal laser scanning microscopy was used to determine the depth of penetration of a reporter molecule (fluorescein isothiocyanate) into the skin. A Franz diffusion assembly was used to examine fluency-related increases in transdermal delivery of transexamic acid. Transdermal delivery of tranexamic acid increased as Er:YAG laser fluency increased. Transdermal delivery was higher when CO2 laser pretreatment was used than when Er:YAG laser pretreatment was used, but a "ceiling effect" was present and increasing the wattage did not cause a further increase in delivery. CO2 laser pretreatment also caused more extensive and deeper skin disruption than Er:YAG laser pretreatment. For conventional, non-fractionated ablative laser pretreatment, the Er:YAG laser would be an optimal choice to enhance transdermal penetration of transexamic acid.

STRONG FIELD PHYSICS WITH MID INFRARED LASERS.

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

POGORELSKY,I.V.

2001-08-27

Mid-infrared gas laser technology promises to become a unique tool for research in strong-field relativistic physics. The degree to which physics is relativistic is determined by a ponderomotive potential. At a given intensity, a 10 {micro}m wavelength CO{sub 2} laser reaches a 100 times higher ponderomotive potential than the 1 {micro}m wavelength solid state lasers. Thus, we can expect a proportional increase in the throughput of such processes as laser acceleration, x-ray production, etc. These arguments have been confirmed in proof-of-principle Thomson scattering and laser acceleration experiments conducted at BNL and UCLA where the first terawatt-class CO{sub 2} lasers aremore » in operation. Further more, proposals for the 100 TW, 100 fs CO{sub 2} lasers based on frequency-chirped pulse amplification have been conceived. Such lasers can produce physical effects equivalent to a hypothetical multi-petawatt solid state laser. Ultra-fast mid-infrared lasers will open new routes to the next generation electron and ion accelerators, ultra-bright monochromatic femtosecond x-ray and gamma sources, allow to attempt the study of Hawking-Unruh radiation, and explore relativistic aspects of laser-matter interactions. We review the present status and experiments with terawatt-class CO{sub 2} lasers, sub-petawatt projects, and prospective applications in strong-field science.« less

Tunable diode lasers application for fully automated absolute measurements of CO and CO2 concentrations in human breath

NASA Astrophysics Data System (ADS)

Moskalenko, Konstantin L.; Sobolev, Nikolai V.; Adamovskay, Inna A.; Stepanov, Eugene V.; Nadezhdinskii, Alexander I.; McKenna-Lawlor, Susan

1994-01-01

Measurements of carbon monoxide and carbon dioxide concentrations by registration of high resolution absorption spectra are described. A fully automated diode laser system developed to simultaneously measure CO and CO2, with sensitivity for CO up to 50 ppb and CO2 up to 0.1 vol%, is described. Calculation of CO and CO2 concentrations was carried out on the base of a priori date on strength and broadening coefficients of detected absorption lines. Test procedures of such diode laser systems are described. Possible reasons affected on accuracy and reliability of obtained data (e.g., the value of diode lasers spontaneous radiation, the stability of CO content in a cell, etc.) for absolute and relative calibration procedure are discussed. The physiological level of CO concentration in the breath of non smokers and smokers under different ambient conditions of CO concentrations in the atmosphere (in Moscow and in Maynooth) are compared. Recent results on statistical studies of the behavior of CO concentrations as a function of breath holding time are represented.

Synchronous and noncollinear infrared upconversion in AgGaS/sub 2/. [JERRY 0999; JERRY 0998; JERRY 1111

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

Bhar, G.C.; Das, S.; Chatterjee, U.

1989-04-17

Synchronous noncollinear upconversion detection is reported for the first time with a Nd:YAG laser in AgGaS/sub 2/. Q-switched pump laser pulses with a repetition rate up to 50 Hz were synchronized with intracavity chopped continuous wave CO/sub 2/ laser pulses. Results were obtained both by tuning the CO/sub 2/ laser and by varying the angle between the laser beams.

Comparative morphological investigation on the rabbit's auricle after exposure to CO2- and Nd:YAG-laser radiation.

PubMed

Wandhöfer, A; Bally, G; Kauffmann, G; Karduck, A

1977-10-31

By comparing the effects of CO2- and Nd:YAG-laser radiation (mainly differing in wave-length by a factor of 10), a surgical instrument suitable for Otorhinolaryngology had to be found. The studies were performed on the rabbit's auricle in order to examine the effect of the laser irradiation mainly on the cartilage. The CO2-laser was found to be more efficient in cutting and caused less extended tissue damage than the Nd:YAG-laser. The latter seems to be more suitable for soft tissue surgery.

Synthesis of the Plasma Chemistry Occurring in High Power CO2 Lasers

DTIC Science & Technology

1978-12-01

AFIT/GEP/PH/78D-13 44 SYNTHESIS OF THE PLASMA CHEMISTRY D D C OCCURRING IN HIGH POWER CO 2 LASERS ’Una CTHESIS David E. Toodle AFIT/GEP/PH/78D-13 2nd...inves- tivation is the plasma chemistry occurring in the laser discharge. These studies are ultimately related to the development of flowing and...aids in the understanding of plasma chemistry pro- cesses in the CO2 laser discharge. I would like to thank the whole staff of the Advanced Concepts

Novel CO2 laser robotic controller outperforms experienced laser operators in tasks of accuracy and performance repeatability.

PubMed

Wong, Yu-Tung; Finley, Charles C; Giallo, Joseph F; Buckmire, Robert A

2011-08-01

To introduce a novel method of combining robotics and the CO(2) laser micromanipulator to provide excellent precision and performance repeatability designed for surgical applications. Pilot feasibility study. We developed a portable robotic controller that appends to a standard CO(2) laser micromanipulator. The robotic accuracy and laser beam path repeatability were compared to six experienced users of the industry standard micromanipulator performing the same simulated surgical tasks. Helium-neon laser beam video tracking techniques were employed. The robotic controller demonstrated superiority over experienced human manual micromanipulator control in accuracy (laser path within 1 mm of idealized centerline), 97.42% (standard deviation [SD] 2.65%), versus 85.11% (SD 14.51%), P = .018; and laser beam path repeatability (area of laser path divergence on successive trials), 21.42 mm(2) (SD 4.35 mm(2) ) versus 65.84 mm(2) (SD 11.93 mm(2) ), P = .006. Robotic micromanipulator control enhances accuracy and repeatability for specific laser tasks. Computerized control opens opportunity for alternative user interfaces and additional safety features. Copyright © 2011 The American Laryngological, Rhinological, and Otological Society, Inc.

Effects of contaminants in CO2 lasers.

NASA Technical Reports Server (NTRS)

Smith, N. S.

1973-01-01

A theoretical model which includes the effects of contaminants is developed for the high flow electric discharge CO2-N2-He laser. The model couples the excitation and relaxation processes, CO2 dissociation, and negative ion formation with the flow processes. An analysis of the effects of CO, O2, NO, and N2O impurities on the average small signal gain is presented. CO decreases the gain by collisional depopulation of the upper laser level, and O2, NO, and N2O reduce the gain by decreasing the electron density by forming stable negative ions. In particular, N2O exhibits a strong quenching effect because of its large dissociation cross section for the formation of O(-).

Wavelength Locking to CO2 Absorption Line-Center for 2-Micron Pulsed IPDA Lidar Application

NASA Technical Reports Server (NTRS)

Refaat, Tamer F.; Petros, Mulugeta; Antill, Charles W.; Singh, Upendra N.; Yu, Jirong

2016-01-01

An airborne 2-micron triple-pulse integrated path differential absorption (IPDA) lidar is currently under development at NASA Langley Research Center (LaRC). This IPDA lidar system targets both atmospheric carbon dioxide (CO2) and water vapor (H2O) column measurements. Independent wavelength control of each of the transmitted laser pulses is a key feature for the success of this instrument. The wavelength control unit provides switching, tuning and locking for each pulse in reference to a 2-micron CW (Continuous Wave) laser source locked to CO2 line-center. Targeting the CO2 R30 line center, at 2050.967 nanometers, a wavelength locking unit has been integrated using semiconductor laser diode. The CO2 center-line locking unit includes a laser diode current driver, temperature controller, center-line locking controller and CO2 absorption cell. This paper presents the CO2 center-line locking unit architecture, characterization procedure and results. Assessment of wavelength jitter on the IPDA measurement error will also be addressed by comparison to the system design.

Diffusion-cooled high-power single-mode waveguide CO2 laser for transmyocardial revascularization

NASA Astrophysics Data System (ADS)

Berishvili, I. I.; Bockeria, L. A.; Egorov, E. N.; Golubev, Vladimir S.; Galushkin, Michail G.; Kheliminsky, A. A.; Panchenko, Vladislav Y.; Roshin, A. P.; Sigaev, I. Y.; Vachromeeva, M. N.; Vasiltsov, Victor V.; Yoshina, V. I.; Zabelin, Alexandre M.; Zelenov, Evgenii V.

1999-01-01

The paper presents the results on investigations and development of multichannel waveguide CO2 laser with diffusion cooling of active medium excited by discharge of audio-frequency alternating current. The description of high-power single-mode CO2 laser with average beam power up to 1 kW is presented. The result of measurement of the laser basic parameters are offered, as well as the outcomes of performances of the laser head with long active zone, operating in waveguide mode. As an example of application of these laser, various capabilities a description of the developed medical system 'Genom' used in the transmyocardial laser revascularization (TMLR) procedure and clinical results of the possibilities of the TMLR in the surgical treatment are presented.

Laser abrasion for cosmetic and medical treatment of facial actinic damage

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

David, L.M.; Lask, G.P.; Glassberg, E.

1989-06-01

Previous studies have shown the carbon dioxide (CO/sub 2/) laser to be effective in the treatment of actinic cheilitis. After CO/sub 2/ laser abrasion, normal skin and marked cosmetic improvement of the lip were noted. In our study, twenty-three patients were treated with CO/sub 2/ laser abrasions for cosmetic improvement of facial lines and actinic changes. Pre- and postoperative histopathologic examinations were made on two patients. Preoperative examination of specimens from actinically damaged skin showed atypical keratinocytes in the basal layer of the epidermis, with overlying dense compact orthokeratosis and parakeratosis. Abundant solar elastosis was seen in the papillary dermis.more » Postoperative histologic specimens showed a normal-appearing epidermis with fibrosis in the papillary dermis and minimal solar elastosis (about four weeks after laser treatment). At present, various modalities are available for the regeneration of the aged skin, including chemical peels and dermabrasion. Significantly fewer complications were noted with CO/sub 2/ laser abrasion than with these methods. Thus, CO/sub 2/ laser abrasion can be useful in the cosmetic and medical treatment of the aged skin. Marked clinical and histologic improvement has been demonstrated.« less

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.

Fractional CO2 lasers for the treatment of atrophic acne scars: a review of the literature.

PubMed

Magnani, Lauren Rose; Schweiger, Eric S

2014-04-01

This review examines the efficacy and safety of fractional CO2 lasers for the treatment of atrophic scarring secondary to acne vulgaris. We reviewed 20 papers published between 2008 and 2013 that conducted clinical studies using fractional CO2 lasers to treat atrophic scarring. We discuss the prevalence and pathogenesis of acne scarring, as well as the laser mechanism. The histologic findings are included to highlight the ability of these lasers to induce the collagen reorganization and formation that improves scar appearance. We considered the number of treatments and different laser settings to determine which methods achieve optimal outcomes. We noted unique treatment regimens that yielded superior results. An overview of adverse effects is included to identify the most common ones. We concluded that more studies need to be done using uniform treatment parameters and reporting in order to establish which fractional CO2 laser treatment approaches allow for the greatest scar improvement.

Pulsed CO2 Laser Ablation of Superficial Basal Cell of Limbs and Trunk: A Comparative Randomized Clinical Trial With Cryotherapy and Surgical Ablation.

PubMed

Zane, Cristina; Facchinetti, Elena; Arisi, Mariachiara; Ortel, Bernhard; Calzavara-Pinton, Piergiacomo

2017-07-01

Pulsed CO2 laser is a treatment of superficial basal cell carcinoma (sBCC) although robust clinical evidence has not been reported so far. The authors investigated efficacy, safety, time to wound healing, cosmetic outcome, patient satisfaction, and cost-effectiveness ratio of pulsed CO2 laser in comparison to cryotherapy and surgery. BCCs of the trunk and extremities were randomized to one of the treatments. After 90 days, efficacy and cosmetic outcome were assessed. Patients recorded the time to complete healing of the wound and scored their overall satisfaction. Two hundred forty patients were randomized. After 3 months, complete remission (CR) rate with pulsed CO2 laser was 78.8%. This was significantly lower than surgery, whereas the CR rate with cryotherapy was not significantly different. Cosmetic result was better with surgery. High satisfaction was reported by 65.0% of patients treated with CO2 ablation. Time of wound healing was significantly shorter with CO2 laser. In comparison to cryotherapy, pulsed CO2 laser showed no statistically significant difference in efficacy, cosmetic outcome, and patient satisfaction. Time to healing was shorter; the cost and cost-effectiveness ratio were similar. Surgery had the greatest efficacy rate. The main limitation of this study was the short duration of follow-up (3 months).

Outcomes of radiofrequency ablation (RFA) and CO2 laser for early glottic cancer.

PubMed

Shuang, Yu; Li, Chao; Zhou, Xuan; Huang, Yongwang; Zhang, Lun

2016-01-01

In the present study, the voice and functional outcomes of radiofrequency ablation (RFA) and CO2 laser for early glottic cancer were evaluated. One hundred sixty eight patients with early glottic cancer from October 2007 to June 2015 were included. Ninety-seven patients underwent RFA and seventy-one patients underwent CO2 laser. The operation time and score of visual analog scale (VAS) for pain on the second day after surgery were recorded. The electronic laryngoscopy was performed at one week, one month and three months of postoperation. The operation time in RFA was shorter than that in CO2 laser (8.52±1.43min vs. 11.76±1.67min, P<0.05). There was no statistical difference in VAS scores between two operation methods (2.86±0.52 vs. 2.89±0.68, P>0.05). One month after operation, the mucosal recovery in RFA group was better than that in CO2 laser group (P<0.05). The alterations of acoustic parameters Jitter, Shimmer and HNR at three time points after operation showed statistical significances in both RFA and CO2 laser groups (P<0.05). The significant differences in acoustic parameters between two groups were also observed (P<0.05). There were no differences in three-year survival rate, local recurrence rate, recurrence rate with anterior commissure involvement and postoperative adhesion rate with anterior commissure between the patients with RFA and CO2 laser (P>0.05). No patient underwent tracheotomy and had symptoms of bucking, dyspnea, severe pain, hemoptysis and other serious complications. Both RFA and CO2 laser are safe and effective for the treatment of early glottic cancer. RFA has the advantage of quick voice recovery, low mucosa injury and short operation time, which is worthy for wide clinical application. Copyright © 2016 Elsevier Inc. All rights reserved.

CO2 laser and/or fluoride enamel treatment against in situ/ex vivo erosive challenge.

PubMed

Jordão, Maísa Camillo; Forti, Gustavo Manzano; Navarro, Ricardo Scarparo; Freitas, Patrícia Moreira; Honório, Heitor Marques; Rios, Daniela

2016-01-01

This in situ/ex vivo study investigated the effect of CO2 laser irradiation and acidulated phosphate fluoride gel (APF) application, separately and in combination, on enamel resistance to erosion. During 2 experimental 5-day crossover phases, 8 volunteers wore intraoral appliances containing bovine enamel blocks which were submitted to four groups: 1st phase - control, untreated and CO2 laser irradiation, 2nd phase - fluoride application and fluoride application before CO2 laser irradiation. Laser irradiation was performed at 10.6 µm wavelength, 5 µs pulse duration and 50 Hz frequency, with average power input and output of 2.3 W and 2.0 W, respectively (28.6 J/cm2). APF gel (1.23%F, pH 3.5) was applied on enamel surface with a microbrush and left on for 4 minutes. Then, the enamel blocks were fixed at the intraoral appliance level. The erosion was performed extraorally 4 times daily for 5 min in 150 mL of cola drink. Enamel loss was measured profilometrically after treatment and after the in situ phase. The data were tested using one-way Repeated Measures Anova and Tukey's test (p<0.05). CO2 laser alone (2.00±0.39 µm) did not show any significantly preventive effect against enamel erosion when compared with the control group (2.41±1.20 µm). Fluoride treated enamel, associated (1.50±0.30 µm) or not (1.47±0.63 µm) with laser irradiation, significantly differed from the control. The APF application decreased enamel wear; however, CO2 laser irradiation did not enhance fluoride ability to reduce enamel wear.

CO2 laser and/or fluoride enamel treatment against in situ/ex vivo erosive challenge

PubMed Central

JORDÃO, Maísa Camillo; FORTI, Gustavo Manzano; NAVARRO, Ricardo Scarparo; FREITAS, Patrícia Moreira; HONÓRIO, Heitor Marques; RIOS, Daniela

2016-01-01

ABSTRACT Objective This in situ/ex vivo study investigated the effect of CO2 laser irradiation and acidulated phosphate fluoride gel (APF) application, separately and in combination, on enamel resistance to erosion. Material and Methods During 2 experimental 5-day crossover phases, 8 volunteers wore intraoral appliances containing bovine enamel blocks which were submitted to four groups: 1st phase - control, untreated and CO2 laser irradiation, 2nd phase - fluoride application and fluoride application before CO2 laser irradiation. Laser irradiation was performed at 10.6 µm wavelength, 5 µs pulse duration and 50 Hz frequency, with average power input and output of 2.3 W and 2.0 W, respectively (28.6 J/cm2). APF gel (1.23%F, pH 3.5) was applied on enamel surface with a microbrush and left on for 4 minutes. Then, the enamel blocks were fixed at the intraoral appliance level. The erosion was performed extraorally 4 times daily for 5 min in 150 mL of cola drink. Enamel loss was measured profilometrically after treatment and after the in situ phase. The data were tested using one-way Repeated Measures Anova and Tukey's test (p<0.05). Results CO2 laser alone (2.00±0.39 µm) did not show any significantly preventive effect against enamel erosion when compared with the control group (2.41±1.20 µm). Fluoride treated enamel, associated (1.50±0.30 µm) or not (1.47±0.63 µm) with laser irradiation, significantly differed from the control. Conclusion The APF application decreased enamel wear; however, CO2 laser irradiation did not enhance fluoride ability to reduce enamel wear. PMID:27383703

O2(a1Δ) quenching in O/O2/O3/CO2/He/Ar mixtures

NASA Astrophysics Data System (ADS)

Azyazov, V. N.; Mikheyev, P. A.; Postell, D.; Heaven, M. C.

2010-02-01

The development of discharge singlet oxygen generators (DSOG's) that can operate at high pressures is required for the power scaling of the discharge oxygen iodine laser. In order to achieve efficient high-pressure DSOG operation it is important to understand the mechanisms by which singlet oxygen (O2(a1Δ)) is quenched in these devices. It has been proposed that three-body deactivation processes of the type O2(a1Δ))+O+M-->2O2+M provide significant energy loss channels. To further explore these reactions the physical and reactive quenching of O2(a1Δ)) in O(3P)/O2/O3/CO2/He/Ar mixtures has been investigated. Oxygen atoms and singlet oxygen molecules were produced by the 248 nm laser photolysis of ozone. The kinetics of O2(a1Δ)) quenching were followed by observing the 1268 nm fluorescence of the O2 a1Δ-X3Ε transition. Fast quenching of O2(a1Δ)) in the presence of oxygen atoms and molecules was observed. The mechanism of the process has been examined using kinetic models, which indicate that quenching by vibrationally excited ozone is the dominant reaction.

INTERACTION OF LASER RADIATION WITH MATTER: Influence of a target on operation of a pulsed CO2 laser emitting microsecond pulses

NASA Astrophysics Data System (ADS)

Baranov, V. Yu; Dolgov, V. A.; Malyuta, D. D.; Mezhevov, V. S.; Semak, V. V.

1987-12-01

The profile of pulses emitted by a TEA CO2 laser with an unstable resonator changed as a result of interaction of laser radiation with the surface of a metal in the presence of a breakdown plasma. This influence of a target on laser operation and its possible applications in laser processing of materials are analyzed.

Thermal investigation on high power dfb broad area lasers at 975 nm, with 60% efficiency

NASA Astrophysics Data System (ADS)

Mostallino, R.; Garcia, M.; Deshayes, Y.; Larrue, A.; Robert, Y.; Vinet, E.; Bechou, L.; Lecomte, M.; Parillaud, O.; Krakowski, M.

2016-03-01

The demand of high power diode lasers in the range of 910-980nm is regularly growing. This kind of device for many applications, such as fiber laser pumping [1], material processing [1], solid-state laser pumping [1], defense and medical/dental. The key role of this device lies in the efficiency (𝜂𝐸) of converting input electrical power into output optical power. The high value of 𝜂𝐸 allows high power level and reduces the need in heat dissipation. The requirement of wavelength stabilization with temperature is more obvious in the case of multimode 975nm diode lasers used for pumping Yb, Er and Yb/Er co-doped solid-state lasers, due to the narrow absorption line close to this wavelength. Such spectral width property (<1 nm), combined with wavelength thermal stabilization (0.07 𝑛𝑚 • °𝐶-1), provided by a uniform distributed feedback grating (DFB) introduced by etching and re-growth process techniques, is achievable in high power diode lasers using optical feedback. This paper reports on the development of the diode laser structure and the process techniques required to write the gratings taking into account of the thermal dissipation and optical performances. Performances are particularly determined in terms of experimental electro-optical characterizations. One of the main objectives is to determine the thermal resistance of the complete assembly to ensure the mastering of the diode laser temperature for operating condition. The classical approach to determine junction temperature is based on the infrared thermal camera, the spectral measurement and the pulse electrical method. In our case, we base our measurement on the spectral measurement but this approach is not well adapted to the high power diodes laser studied. We develop a new measurement based on the pulse electrical method and using the T3STERequipment. This method is well known for electronic devices and LEDs but is weakly developed for the high power diodes laser. This crucial measurement compared to spectral one is critical for understand the thermal management of diode laser device and improve the structure based on design for reliability. To have a perfect relation between structure, and their modification, and temperature, FEM simulations are performed using COMSOL software. In this case, we can understand the impact of structure on the isothermal distribution and then reveal the sensitive zones in the diode laser. To validate the simulation, we compare the simulation results to the experimental one and develop an analytical model to determine the different contributions of the thermal heating. This paper reports on the development laser structure and the process techniques required to write the gratings. Performances are particularly characterized in terms of experimental electro-optical characterization and spectral response. The extraction of thermal resistance (Rth) is particularly difficult, because of the implicit low value (Rth ≈ 2𝐾/𝑊) and the multimodal nature of the diode laser. In such a context, thermal resistance has been measured using a dedicated equipment namely T3STER©. The results have been compared with those given by the well-known technique achieved from the spectrum of the diode laser (central wavelength variations vs temperature) that is more difficult to apply for multimodal diodes laser. The last section deals with thermal simulations based on finite elements method (FEM) modeling in order to estimate junction temperature . This study represent a significant part of the general Design for Reliability (DfR) effort carried out on such devices to produce efficient and reliable high power devices at the industrial level.

Raman Spectroscopic Measurements of Co2 Dissolved in Seawater for Laser Remote Sensing in Water

NASA Astrophysics Data System (ADS)

Somekawa, Toshihiro; Fujita, Masayuki

2016-06-01

We examined the applicability of Raman lidar technique as a laser remote sensing tool in water. The Raman technique has already been used successfully for measurements of CO2 gas dissolved in water and bubbles. Here, the effect of seawater on CO2 Raman spectra has been evaluated. A frequency doubled Q-switched Nd:YAG laser (532 nm) was irradiated to CO2 gas dissolved in a standard seawater. In seawater, the Raman signals at 984 and 1060-1180 cm-1 from SO42- were detected, which shows no spectral interference caused by Raman signals derived from CO2.

Monolithic thermally bonded Er3+, Yb3+:glass/Co2+:MgAl2O4 microchip lasers

NASA Astrophysics Data System (ADS)

Mlynczak, Jaroslaw; Belghachem, Nabil

2015-12-01

The highest ever reported 10 kW peak power in monolithic thermally bonded Er3+, Yb3+:glass/Co2+:MgAl2O4 microchip laser was achieved. To show the superiority of monolithic microchip lasers over those with external mirrors the laser generation characteristics of the same samples in both cases were compared.

Intense laser beams; Proceedings of the Meeting, Los Angeles, CA, Jan. 23, 24, 1992

NASA Technical Reports Server (NTRS)

Wade, Richard C. (Editor); Ulrich, Peter B. (Editor)

1992-01-01

Various papers on intense laser beams are presented. Individual topics addressed include: novel methods of copper vapor laser excitation, UCLA IR FEL, lasing characteristics of a large-bore copper vapor laser (CVL), copper density measurement of a large-bore CVL, high-power XeCl excimer laser, solid state direct-drive circuit for pumping gas lasers, united energy model for FELs, intensity and frequency instabilities in double-mode CO2 lasers, comparison of output power stabilities of CO and CO2 lasers, increasing efficiency of sealed-off CO lasers, thermal effects in singlet delta oxygen generation, optical extraction from the chemical oxygen-iodine laser medium, generation and laser diagnostic analysis of bismuth fluoride. Also discussed are: high-Q resonator design for an HF overtone chemical lasers, improved coatings for HF overtone lasers, scaled atmospheric blooming experiment, simulation on producing conjugate field using deformable mirrors, paraxial theory of amplitude correction, potential capabilities of adaptive optical systems in the atmosphere, power beaming research at NASA, system evaluations of laser power beaming options, performance projections for laser beam power to space, independent assessment of laser power beaming options, removal of atmospheric CFCs by lasers, efficiency of vaporization cutting by CVL.

Combination of CO2 and Q-switched Nd:YAG lasers is more effective than Q-switched Nd:YAG laser alone for eyebrow tattoo removal.

PubMed

Radmanesh, Mohammad; Rafiei, Zohreh

2015-04-01

The eyebrow tattoo removal using Q-switched lasers is usually prolonged. Other modalities may be required to enhance the efficacy and shorten the treatment course. To compare the efficacy of Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser alone versus combination of Q-switched Nd:YAG and Ultrapulse CO2 lasers for eyebrow tattoo removal after a single session. After local anesthesia, the right eyebrow of 20 patients was treated with Ultrapulse CO2 laser with the parameters of 4 J/cm(2) and 3.2 J/cm(2) for the first and the second passes. Both eyebrows were then treated with 1064-nm and 532-nm Q-switched Nd:YAG laser. The spot size and pulse duration were 3 mm and 5 nanoseconds for both wavelengths, and the fluence was 7 J/cm(2) for 1064 nm and 3 J/cm (2) for 532 nm. The side treated with combination of Q-switched Nd:YAG and CO2 lasers improved 75-100% in 6 of 20 patients versus only 1 of 20 in the side treated with Q-switched Nd:YAG alone. Similarly, the right side in 13 of 20 patients showed more than 50% improvement with combination therapy versus the left side (the monotherapy side), where only 6 of 20 cases showed more than 50% improvement. The Mann-Whitney test was 2.85 for the right side and 1.95 for the left side (P value = 0.007). Using Ultra pulse CO2 laser enhances the efficacy of Q-switched Nd:YAG laser in eyebrow tattoo removal.

A new second-puncture probe for CO2 laser laparoscopy.

PubMed

Daniell, J F; Herbert, C M

1985-02-01

A new second-puncture probe system was designed for aiming and firing the CO2 laser under laparoscopic control. The probe allows simultaneous suction of the smoke from vaporization and insufflation of fresh CO2 for maintenance of an adequate pneumoperitoneum during use. A 200-mm focusing lens attaches the probe to any surgical CO2 laser with an articulated arm. The new probe is 10 cm shorter than standard probes, allowing the application of a wider range of power densities during laser laparoscopy and making surgery easier to perform. Our initial experiences with this new instrument have involved both laboratory animals and patients with endometriosis, adnexal adhesions and distal tubal obstruction.

Multiline CO2 laser with Q-switching for generation of terahertz radiation

NASA Astrophysics Data System (ADS)

Ionin, A. A.; Kinyaevskiy, I. O.; Klimachev, Yu M.; Stepanishchev, V. V.; Khafizov, I. Zh

2017-12-01

In this paper we consider the method of obtaining THz radiation by difference frequency generation (DFG) of multiline CO2 laser. For this purpose a multiline CO2 laser with Q-switching was created. The three strongest lines, 9 R(18), 9 P(20) and 9 P(22) with wavelengths ∼9.28, ∼9.55 and ∼9.57 μm respectively, held 85% of CO2 laser power, and can be used to obtain difference frequency at a wavelength of ∼310 μm. DFG of other spectral lines fall within the range of 263 ÷ 8100 μm. Different nonlinear crystals for DFG and filters to separate THz radiation were considered.

Method and device for stand-off laser drilling and cutting

DOEpatents

Copley, John A.; Kwok, Hoi S.; Domankevitz, Yacov

1989-09-26

A device for perforating material and a method of stand-off drilling using a laser. In its basic form a free-running laser beam creates a melt on the target and then a Q-switched short duration pulse is used to remove the material through the creation of a laser detonation wave. The advantage is a drilling/cutting method capable of working a target at lengthy stand-off distance. The device may employ 2 lasers or a single one operated in a free-running/Q-switched dual mode.

Combined Tin-Containing Fluoride Solution and CO2 Laser Treatment Reduces Enamel Erosion in vitro.

PubMed

Esteves-Oliveira, Marcella; Witulski, Nadine; Hilgers, Ralf-Dieter; Apel, Christian; Meyer-Lueckel, Hendrik; Eduardo, Carlos de Paula

2015-01-01

The aim of this in vitro study was to evaluate the effect of combined CO2 laser and tin-containing fluoride treatment on the formation and progression of enamel erosive lesions. Ninety-six human enamel samples were obtained, stored in thymol solution and, after surface polishing, randomly divided into 6 different surface treatment groups (n = 16 in each group) as follows: no treatment, control (C); one CO2 laser irradiation (L1); two CO2 laser irradiations (L2); daily application of fluoride solution (F); combined daily fluoride solution + one CO2 laser irradiation (L1F), and combined daily fluoride solution + two CO2 laser irradiations (L2F). Laser irradiation was performed at 0.3 J/cm2 (5 µs/226 Hz/10.6 µm) on day 1 (L1) and day 6 (L2). The fluoride solution contained AmF/NaF (500 ppm F), and SnCl2 (800 ppm Sn) at pH 4.5. After surface treatment the samples were submitted to an erosive cycling over 10 days, including immersion in citric acid (2 min/0.05 M/pH = 2.3) 6 times daily and storage in remineralization solution (≥1 h) between erosive attacks. At the end of each cycling day, the enamel surface loss (micrometers) was measured using a 3D laser profilometer. Data were statistically analyzed by means of a 2-level mixed effects model and linear contrasts (α = 0.05). Group F (-3.3 ± 2.0 µm) showed significantly lower enamel surface loss than groups C (-27.22 ± 4.1 µm), L1 (-18.3 ± 4.4 µm) and L2 (-16.3 ± 5.3 µm) but higher than L1F (-1.0 ± 4.4 µm) and L2F (1.4 ± 3.2 µm, p < 0.05). Under the conditions of this in vitro study, the tin-containing fluoride solution caused 88% reduction of enamel surface loss, while its combination with CO2 laser irradiation at 0.3 J/cm2 hampered erosive loss almost completely. © 2015 S. Karger AG, Basel.

HairMax LaserComb laser phototherapy device in the treatment of male androgenetic alopecia: A randomized, double-blind, sham device-controlled, multicentre trial.

PubMed

Leavitt, Matt; Charles, Glenn; Heyman, Eugene; Michaels, David

2009-01-01

The use of low levels of visible or near infrared light for reducing pain, inflammation and oedema, promoting healing of wounds, deeper tissue and nerves, and preventing tissue damage has been known for almost 40 years since the invention of lasers. The HairMax LaserComb is a hand-held Class 3R lower level laser therapy device that contains a single laser module that emulates 9 beams at a wavelength of 655 nm (+/-5%). The device uses a technique of parting the user's hair by combs that are attached to the device. This improves delivery of distributed laser light to the scalp. The combs are designed so that each of the teeth on the combs aligns with a laser beam. By aligning the teeth with the laser beams, the hair can be parted and the laser energy delivered to the scalp of the user without obstruction by the individual hairs on the scalp. The primary aim of the study was to assess the safety and effectiveness of the HairMax LaserComb laser phototherapy device in the promotion of hair growth and in the cessation of hair loss in males diagnosed with androgenetic alopecia (AGA). This double-blind, sham device-controlled, multicentre, 26-week trial randomized male patients with Norwood-Hamilton classes IIa-V AGA to treatment with the HairMax LaserComb or the sham device (2 : 1). The sham device used in the study was identical to the active device except that the laser light was replaced by a non-active incandescent light source. Of the 110 patients who completed the study, subjects in the HairMax LaserComb treatment group exhibited a significantly greater increase in mean terminal hair density than subjects in the sham device group (p < 0.0001). Consistent with this evidence for primary effectiveness, significant improvements in overall hair regrowth were demonstrated in terms of patients' subjective assessment (p < 0.015) at 26 weeks over baseline. The HairMax LaserComb was well tolerated with no serious adverse events reported and no statistical difference in adverse effects between the study groups. The results of this study suggest that the HairMax LaserComb is an effective, well tolerated and safe laser phototherapy device for the treatment of AGA in males.

Reactivation of a Tin-Oxide-Containing Catalyst

NASA Technical Reports Server (NTRS)

Hess, Robert; Sidney, Barry; Schryer, David; Miller, Irvin; Miller, George; Upchurch, Bill; Davis, Patricia; Brown, Kenneth

2010-01-01

The electrons in electric-discharge CO2 lasers cause dissociation of some CO2 into O2 and CO, and attach themselves to electronegative molecules such as O2, forming negative O2 ions, as well as larger negative ion clusters by collisions with CO or other molecules. The decrease in CO2 concentration due to dissociation into CO and O2 will reduce the average repetitively pulsed or continuous wave laser power, even if no disruptive negative ion instabilities occur. Accordingly, it is the primary object of this invention to extend the lifetime of a catalyst used to combine the CO and O2 products formed in a laser discharge. A promising low-temperature catalyst for combining CO and O2 is platinum on tin oxide (Pt/SnO2). First, the catalyst is pretreated by a standard procedure. The pretreatment is considered complete when no measurable quantity of CO2 is given off by the catalyst. After this standard pretreatment, the catalyst is ready for its low-temperature use in the sealed, high-energy, pulsed CO2 laser. However, after about 3,000 minutes of operation, the activity of the catalyst begins to slowly diminish. When the catalyst experiences diminished activity during exposure to the circulating gas stream inside or external to the laser, the heated zone surrounding the catalyst is raised to a temperature between 100 and 400 C. A temperature of 225 C was experimentally found to provide an adequate temperature for reactivation. During this period, the catalyst is still exposed to the circulating gas inside or external to the laser. This constant heating and exposing the catalyst to the laser gas mixture is maintained for an hour. After heating and exposing for an appropriate amount of time, the heated zone around the catalyst is allowed to return to the nominal operating temperature of the CO2 laser. This temperature normally resides in the range of 23 to 100 C. Catalyst activity can be measured as the percentage conversion of CO to CO2. In the specific embodiment described above, the initial steady-state conversion percentage was 70 percent. After four days, this conversion percentage decreased to 67 percent. No decrease in activity is acceptable because the catalyst must maintain its activity for long periods of time. After being subjected to the reactivation process of the present invention, the conversion percentage rose to 77 percent. Such a reactivation not only returned the catalyst to its initial steady state but resulted in a 10-percent improvement over the initial steady state value.

Laser tweezer actuated microphotonic array devices for high resolution imaging and analysis in chip-based biosystems

NASA Astrophysics Data System (ADS)

Birkbeck, Aaron L.

A new technology is developed that functionally integrates arrays of lasers and micro-optics into microfluidic systems for the purpose of imaging, analyzing, and manipulating objects and biological cells. In general, the devices and technologies emerging from this area either lack functionality through the reliance on mechanical systems or provide a serial-based, time consuming approach. As compared to the current state of art, our all-optical design methodology has several distinguishing features, such as parallelism, high efficiency, low power, auto-alignment, and high yield fabrication methods, which all contribute to minimizing the cost of the integration process. The potential use of vertical cavity surface emitting lasers (VCSELs) for the creation of two-dimensional arrays of laser optical tweezers that perform independently controlled, parallel capture, and transport of large numbers of individual objects and biological cells is investigated. One of the primary biological applications for which VCSEL array sourced laser optical tweezers are considered is the formation of engineered tissues through the manipulation and spatial arrangement of different types of cells in a co-culture. Creating devices that combine laser optical tweezers with select micro-optical components permits optical imaging and analysis functions to take place inside the microfluidic channel. One such device is a micro-optical spatial filter whose motion and alignment is controlled using a laser optical tweezer. Unlike conventional spatial filter systems, our device utilizes a refractive optical element that is directly incorporated onto the lithographically patterned spatial filter. This allows the micro-optical spatial filter to automatically align itself in three-dimensions to the focal point of the microscope objective, where it then filters out the higher frequency additive noise components present in the laser beam. As a means of performing high resolution imaging in the microfluidic channel, we developed a novel technique that integrates the capacity of a laser tweezer to optically trap and manipulate objects in three-dimensions with the resolution-enhanced imaging capabilities of a solid immersion lens (SIL). In our design, the SIL is a free-floating device whose imaging beam, motion control and alignment is provided by a laser optical tweezer, which allows the microfluidic SIL to image in areas that are inaccessible to traditional solid immersion microscopes.

High Repetition Rate Pulsed 2-Micron Laser Transmitter for Coherent CO2 DIAL Measurement

NASA Technical Reports Server (NTRS)

Singh, Uprendra N.; Bai, Yingxin; Yu, Jirong; Petros, Mulugeta; Petzar, Paul J.; Trieu, Bo C.; Lee, Hyung

2009-01-01

A high repetition rate, highly efficient, Q-switched 2-micron laser system as the transmitter of a coherent differential absorption lidar for CO2 measurement has been developed at NASA Langley Research Center. Such a laser transmitter is a master-slave laser system. The master laser operates in a single frequency, either on-line or off-line of a selected CO2 absorption line. The slave laser is a Q-switched ring-cavity Ho:YLF laser which is pumped by a Tm:fiber laser. The repetition rate can be adjusted from a few hundred Hz to 10 kHz. The injection seeding success rate is from 99.4% to 99.95%. For 1 kHz operation, the output pulse energy is 5.5mJ with the pulse length of approximately 50 ns. The optical-to-optical efficiency is 39% when the pump power is 14.5W. The measured standard deviation of the laser frequency jitter is about 3 MHz.

Control of laser pulse waveform in longitudinally excited CO2 laser by adjustment of excitation circuit

NASA Astrophysics Data System (ADS)

Uno, Kazuyuki; Jitsuno, Takahisa

2018-05-01

In a longitudinally excited CO2 laser that had a 45 cm-long discharge tube with a 1:1:2 mixture of CO2/N2/He gas at a pressure of 3.0 kPa, we realized the generation of a short laser pulse with a spike pulse width of about 200 ns and a pulse tail length of several tens of microseconds, control of the energy ratio of the spike pulse part to the pulse tail part in the short laser pulse, the generation of a long laser pulse with a pulse width of several tens of microseconds, and control of the pulse width in the long laser pulse, by using four types of excitation circuits in which the capacitance was adjusted. In the short laser pulse, the energy ratio was in the range 1:14-1:112. In the long laser pulse, the pulse width was in the range 25.7-82.7 μs.

Development of a Pulsed 2-micron Laser Transmitter for CO2 Sensing from Space

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Yu, Jirong; Bai, Yingxin; Petros, Mulugeta; Menzies, Robert T.

2011-01-01

NASA Langley Research Center (LaRC), in collaboration with NASA Jet Propulsion Laboratory (JPL), is engaged in the development and demonstration of a highly efficient, versatile, 2-micron pulsed laser that can be used in a pulsed Differential Absorption Lidar (DIAL)/Integrated Path Differential Absorption (IPDA) instrument to make precise, high-resolution CO2 measurements to investigate sources, sinks, and fluxes of CO2. This laser transmitter will feature performance characteristics needed for an ASCENDS system that will be capable of delivering the CO2 measurement precision required by the Earth Science Decadal Survey (DS).

Deflagration-to-detonation characteristics of a laser exploding bridge detonator

NASA Astrophysics Data System (ADS)

Welle, E. J.; Fleming, K. J.; Marley, S. K.

2006-08-01

Evaluation of laser initiated explosive trains has been an area of extreme interest due to the safety benefits of these systems relative to traditional electro-explosive devices. A particularly important difference is these devices are inherently less electro-static discharge (ESD) sensitive relative to traditional explosive devices due to the isolation of electrical power and associated materials from the explosive interface. This paper will report work conducted at Sandia National Laboratories' Explosive Components Facility, which evaluated the initiation and deflagration-to-detonation characteristics of a Laser Driven Exploding Bridgewire detonator. This paper will report and discuss characteristics of Laser Exploding Bridgewire devices loaded with hexanitrohexaazaisowurtzitane (CL-20) and tetraammine-cis-bis-(5-nitro-2H-tetrazolato-N2) cobalt (III) perchlorate (BNCP).

Transition metal-doped zinc chalcogenides: Spectroscopy and laser demonstration of a new class of gain media

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

DeLoach, L.D.; Page, R.H.; Wilke, G.D.

The absorption and emission properties of transition metal (TM)-doped Zinc chalcogenides have been investigated to understand their potential application as room-temperature, mid-infrared tunable laser media. Crystals of ZnS, ZnSe, and ZnTe, individually doped with Cr{sup 2+}, Co{sup 2+}, Ni{sup 2+}, or Fe{sup 2+}, have been evaluated. The absorption and emission properties are presented and discussed in terms of the energy levels from which they arise. The absorption spectra of the crystals studied exhibit strong bands between 1.4 and 2.0 {micro}m which overlap with the output of strained-layer InGaAs diodes. The room-temperature emission spectra reveal wide-band emissions from 2--3 {micro}m formore » Cr and from 2.8--1.0 {micro}m for Co. Laser demonstrations of Cr:ZnS and Cr:ZnSe have been performed in a laser-pumped laser cavity with a Co:MgF{sub 2} pump laser. The output of both lasers were determined to peak at wavelengths near 2.35 {micro}m, and both lasers demonstrated a maximum slope efficiency of approximately 20%. Based on these initial results, the Cr{sup 2+} ion is predicted to be a highly favorable laser ion for the mid-IR when doped into the zinc chalcogenides; Co{sup 2+} may also serve usefully, but laser demonstrations yet remain to be performed.« less

Recurrence rate and patient satisfaction of CO2 laser evaporation of lesions in patients with hidradenitis suppurativa: a retrospective study.

PubMed

Mikkelsen, Peter Riis; Dufour, Deirde Nathalie; Zarchi, Kian; Jemec, Gregor B E

2015-02-01

Hidradenitis suppurativa (HS) is a debilitating disease and is difficult to treat. Validation of surgical techniques is therefore of great importance in the management of HS. Carbon dioxide (CO2) laser evaporation has been shown effective, but larger-scale studies are scarce. To determine the recurrence rate, time to recurrence, and factors influencing disease recurrence in skin treated with CO2 laser evaporation, and healing by secondary intention; and patients' satisfaction with treatment. Fifty-eight patients treated with CO2 laser evaporation were interviewed regarding recurrence and satisfaction after a mean of 25.7 months. Seventeen of 58 (29%) reported recurrence of HS lesions within the borders of the treated areas after a mean of 12.7 months. Obesity was a risk factor for recurrence with a hazard ratio of 4.53. Fifty-five patients (95%) reported some or great improvement, and 91% would recommend the CO2 laser surgery to other HS patients. This study supports the claim that CO2 laser treatment is an effective modality for recurrent HS lesions in a majority of patients. The authors identified obesity as a risk factor for recurrence. Self-reported satisfaction is high, and only 3 of 58 report no change in the condition. None reported a worsening.

Enhanced human osteoblast cell adhesion and proliferation on 316 LS stainless steel by means of CO2 laser surface treatment.

PubMed

Hao, L; Lawrence, J; Phua, Y F; Chian, K S; Lim, G C; Zheng, H Y

2005-04-01

An effective and novel technique for improving the biocompatibility of a biograde 316 LS stainless steel through the application of CO(2) laser treatment to modify the surface properties of the material is described herein. Different surface properties, such as surface roughness, surface oxygen content, and surface energy for CO(2) laser-treated 316 LS stainless steel, untreated, and mechanically roughened samples were analyzed, and their effects on the wettability characteristics of the material were studied. It was found that modification of the wettability characteristics of the 316 LS stainless steel following CO(2) laser treatment was achieved. This improvement was identified as being mainly due to the change in the polar component of the surface energy. One-day cell adhesion tests showed that cells not only adhered and spread better, but also grew faster on the CO(2) laser-treated sample than on either the untreated or mechanically roughened sample. Further, compared with the untreated sample, MTT cell proliferation analysis revealed that the mechanically roughed surface resulted in a slight enhancement, and CO(2) laser treatment brought about a significant increase in cell proliferation. An increase in the wettability of the 316 LS stainless steel was observed to positively correlate with the cell proliferation. (c) 2004 Wiley Periodicals, Inc.

Fractional CO2 laser for vulvovaginal atrophy (VVA) dyspareunia relief in breast cancer survivors.

PubMed

Pieralli, Annalisa; Fallani, Maria Grazia; Becorpi, Angelamaria; Bianchi, Claudia; Corioni, Serena; Longinotti, Manuela; Tredici, Zelinda; Guaschino, Secondo

2016-10-01

The aim of this study was to evaluate the efficacy of fractional CO2 laser therapy in breast cancer survivors as a therapeutic method for vulvovaginal atrophy (VVA) dyspareunia. 50 patients (mean age 53.3 years) underwent fractional microablative CO2 laser treatment for dyspareunia in oncological menopause (mean time of menopause 6.6 years). The Gloria Bachmann's Vaginal Health Index (VHI) score was chosen as system to evaluate the presence of VVA and its improvement after the treatment. Intensity of dyspareunia was evaluated using a visual analog scale (VAS). Data indicated a significant improvement in VVA dyspareunia (p < 1.86e-22) in breast cancer survivors who had undergone 3 sessions of vaginal fractional CO2 laser treatment. Moreover, VHI scores were significantly higher 30 days post-treatment (T4) (p < 0.0001). 76 % of patients were satisfied or very satisfied with the treatment results. The majority (52 %) of patients were satisfied after a long-term follow-up (mean time 11 months). No adverse events due to fractional CO2 laser treatment occurred. The treatment with fractionated CO2 laser appeared to be a feasible and effective treatment for VVA dyspareunia in breast cancer survivors with contraindications to hormonal treatments.

The dynamics of a surface plasma generated by an independent source in the field of laser emission

NASA Astrophysics Data System (ADS)

Kovalev, A. S.; Popov, A. M.; Seleznev, B. V.; Feoktistov, V. A.

1986-09-01

A study is made of the evolution of a plasma formation generated by a high-power short pulse of an Nd laser on a metal surface, with the relatively weak emission of a CO2 laser focused on the surface. The thresholds of a sustained breakdown plasma are measured as a function of the plasma-generating pulse energy. The dynamics of plasma front propagation along the target surface and in the direction opposite to the laser beam direction is investigated. It is shown that the use of an additional laser with an energy less than that of the CO2 laser by 2-3 orders of magnitude makes it possible to generate a surface plasma capable of absorbing and transferring to the target a significantly greater fraction of the CO2 laser energy.

Influence of CO2 (10.6 μm) and Nd:YAG laser irradiation on the prevention of enamel caries around orthodontic brackets.

PubMed

Seino, Priscila Yumi; Freitas, Patrícia Moreira; Marques, Márcia Martins; de Souza Almeida, Fernanda Campos; Botta, Sérgio Brossi; Moreira, Maria Stella Nunes Araújo

2015-02-01

One possible undesirable consequence of orthodontic therapy is the development of incipient caries lesions of enamel around brackets. The aim of this study was to compare the effects of CO2 (λ = 10.6 μm) and Nd:YAG (λ = 1,064 nm) lasers associated or not with topical fluoride application on the prevention of caries lesions around brackets. Brackets were bonded to the enamel of 65 premolars. The experimental groups (n = 13) were: G1--application of 1.23% acidulated fluoride phosphate gel (AFP, control); G2--Nd:YAG laser irradiation (0.6 W, 84.9 J/cm(2), 10 Hz, 110 μs, contact mode); G3--Nd:YAG laser irradiation associated with AFP; G4--CO2 laser irradiation (0.5 W, 28.6 J/cm(2), 50 Hz, 5 μs, and 10 mm focal distance); and G5--CO2 laser irradiation associated with AFP. Quantitative light-induced fluorescence was used to assess enamel demineralization. The data were statistically compared (α = 5%). The highest demineralization occurred in the Nd:YAG laser group (G2, 26.15% ± 1.94). The demineralization of all other groups was similar to that of the control group. In conclusion, CO2 laser alone was able to control enamel demineralization around brackets at the same level as that obtained with topical fluoride application.

Pulpal safety of 9.6 microm TEA CO2 laser used for caries prevention.

PubMed

Goodis, Harold E; Fried, Daniel; Gansky, Stuart; Rechmann, Peter; Featherstone, John D B

2004-01-01

Lasers are used for several procedures involving hard and soft tissues of the oral cavity. A potential future application is the use of the CO2 laser to alter the surface structure of tooth enamel to render it more resistant to caries. A new 9.6 microm wavelength transverse excited atmospheric pressure (TEA) CO2 laser (Argus Photonics, Jupiter, FL) has been investigated as a device that can be used for this purpose without harming the dental pulp. Erupted caries- and restoration-free third molars (n = 24 participants; 74 teeth) were used in the study. Teeth were irradiated at an incident fluence of 1.5 J/cm2, a repetition rate of 10 Hz and a spot size 1 mm in diameter. At the low and high settings, 200-400 pulses at 5-8 microseconds pulse duration were delivered at 12 mJ per pulse for a total energy of 2.4 or 4.8 J delivered for 20 or 40 seconds, respectively. Other teeth were subjected to a sham dental procedure (positive control) or no procedure (negative control). Prior to testing, radiographs were taken of all teeth, and they were assessed pulpally using heat, cold, and electricity to determine vitality. The teeth were removed either immediately or at 1 week or 1 month after testing. Teeth were bioprepared and examined histologically for signs of inflammation. Only one tooth developed symptoms of sensitivity to cold for 10 days following exposure to the high power level. The sensitivity was of fleeting duration and was judged to be reversible pulpitis. All teeth tested responded normally at pre-testing and pre-extraction time periods. Histological examination of all teeth disclosed no indication of an inflammatory response in the pulp tissue at any time point. All sections appeared normal with no changes seen in the normal pulpal morphology. We conclude that the 9.6 microm wavelength laser causes no permanent/serious pulpal damage at the energy levels used and can be used safely for caries prevention treatments in humans.

2D Ruddlesden-Popper Perovskites Microring Laser Array.

PubMed

Zhang, Haihua; Liao, Qing; Wu, Yishi; Zhang, Zhaoyi; Gao, Qinggang; Liu, Peng; Li, Meili; Yao, Jiannian; Fu, Hongbing

2018-04-01

3D organic-inorganic hybrid perovskites have featured high gain coefficients through the electron-hole plasma stimulated emission mechanism, while their 2D counterparts of Ruddlesden-Popper perovskites (RPPs) exhibit strongly bound electron-hole pairs (excitons) at room temperature. High-performance solar cells and light-emitting diodes (LEDs) are reported based on 2D RPPs, whereas light-amplification devices remain largely unexplored. Here, it is demonstrated that ultrafast energy transfer along cascade quantum well (QW) structures in 2D RPPs concentrates photogenerated carriers on the lowest-bandgap QW state, at which population inversion can be readily established enabling room-temperature amplified spontaneous emission and lasing. Gain coefficients measured for 2D RPP thin-films (≈100 nm in thickness) are found about at least four times larger than those for their 3D counterparts. High-density large-area microring arrays of 2D RPPs are fabricated as whispering-gallery-mode lasers, which exhibit high quality factor (Q ≈ 2600), identical optical modes, and similarly low lasing thresholds, allowing them to be ignited simultaneously as a laser array. The findings reveal that 2D RPPs are excellent solution-processed gain materials potentially for achieving electrically driven lasers and ideally for on-chip integration of nanophotonics. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Generation of energetic, picosecond seed pulses for CO2 laser using Raman shifter

NASA Astrophysics Data System (ADS)

Welch, Eric; Tochitsky, Sergei; Joshi, Chan

2017-03-01

We present a new concept for generating 3 ps seed pulses for a high-power CO2 laser amplifier that are multiple orders more energetic than seed pulses generated by slicing from a nanosecond CO2 laser pulse. We propose to send a 1 µm picosecond laser through a C6D6 Raman shifter and mix both the pump and shifted components in a DFG crystal to produce pulses at 10.6 µm. Preliminary results of a proof-of-principle experiment are presented.

The efficacy and safety of the flexible fiber CO2 laser delivery system in the endoscopic management of pediatric airway problems: Our long term experience.

PubMed

Lee, Gi Soo; Irace, Alexandra; Rahbar, Reza

2017-06-01

To report the use of flexible fiber CO2 laser in the endoscopic management of pediatric airway cases. A retrospective review was conducted of patients who underwent CO2 laser-assisted airway procedures between September 2007 and January 2014 at a tertiary pediatric hospital. Sixty-eight patients underwent 80 procedures utilizing flexible fiber CO2 laser. Procedures included supraglottoplasty (n = 32), laryngeal cleft repair (type I [n = 10], type II [n = 7], type III [n = 6]), suprastomal granuloma excision (n = 6), cordotomy (n = 4), laryngeal neurofibroma excision (n = 4), laryngeal granulomatous mass excision (n = 1), subglottic stenosis excision (n = 6), division of glottic web (n = 2), subglottic cyst excision (n = 1), and supraglottic biopsy (n = 1). Ages ranged from 8 days to 21 years (median 11 months). No intraoperative or postoperative complications related to the use of laser were noted. The flexible fiber CO2 laser can be safely and effectively used to address a variety of pediatric airway lesions. Previously, the use of CO2 laser in minimally invasive airway surgery has been limited due to the articulating arm carrier, absence of a hand piece, and the direct line-of sight view required. The fiber allows the cutting beam to be directed at the site of the lesion and bypasses limitations posed by other laser systems. Copyright © 2017 Elsevier B.V. All rights reserved.

High-powered CO2 -lasers and noise control

NASA Astrophysics Data System (ADS)

Honkasalo, Antero; Kuronen, Juhani

High-power CO2 -lasers are being more and more widely used for welding, drilling and cutting in machine shops. In the near future, different kinds of surface treatments will also become routine practice with laser units. The industries benefitting most from high power lasers will be: the automotive industry, shipbuilding, the offshore industry, the aerospace industry, the nuclear and the chemical processing industries. Metal processing lasers are interesting from the point of view of noise control because the working tool is a laser beam. It is reasonable to suppose that the use of such laser beams will lead to lower noise levels than those connected with traditional metal processing methods and equipment. In the following presentation, the noise levels and possible noise-control problems attached to the use of high-powered CO2 -lasers are studied.

Laser myringotomy with the CO2 Otoscan laser

NASA Astrophysics Data System (ADS)

Sedlmaier, Benedikt W.; Jivanjee, Antonio; Schoenfeld, Uwe; Jovanovic, Sergije

2000-06-01

Tympanic ventilation is the treatment of choice for otitis media with effusion (OME). CO2 laser myringotomy has already proven its value and is finding increasing clinical application. The ventilation time in the middle ear is essentially determined by the size of the laser perforation. Perforations exceeding 2 mm in diameter enable tympanic ventilation for about three weeks and thus compete with the ventilation tube in the treatment of OME. IN a prospective study, laser myringotomy is performed in 84 children with OME with the new CO2 laser otoscope Otoscan. The closure time was 17 days in average for a preformation diameter of 2 mm. In the further clinical course, the ear-drums healed without atrophic scar formation. In an observation period of six month the recurrency rate of effusion was approximately 10 percent. Laser myringotomy seems to be an useful method in the operative therapy of secretory otitis media.

Atmospheric transmission of CO2 laser radiation with application to laser Doppler systems

NASA Technical Reports Server (NTRS)

Murty, S. S. R.

1975-01-01

The molecular absorption coefficients of carbon dioxide, water vapor, and nitrous oxide are calculated at the P16, P18, P20, P22, and P24 lines of the CO2 laser for temperatures from 200 to 300 K and for pressures from 100 to 1100 mb. The temperature variation of the continuum absorption coefficient of water vapor is taken into account semi-empirically from Burch's data. The total absorption coefficient from the present calculations falls within + or - 20 percent of the results of McClatchey and Selby. The transmission loss which the CO2 pulsed laser Doppler system experiences was calculated for flight test conditions for the five P-lines. The total transmission loss is approximately 7 percent higher at the P16 line and 10 percent lower at the P24 line compared to the P20 line. Comparison of the CO2 laser with HF and DF laser transmission reveals the P2(8) line at 3.8 micrometers of the DF laser is much better from the transmission point of view for altitudes below 10 km.

Treatment of tooth fracture by medium-energy CO2 laser and DP-bioactive glass paste: the interaction of enamel and DP-bioactive glass paste during irradiation by CO2 laser.

PubMed

Lin, C P; Tseng, Y C; Lin, F H; Liao, J D; Lan, W H

2001-03-01

Acute trauma or trauma associated with occlusal disturbance can produce tooth crack or fracture. Although several methods are proposed to treat the defect, however, the prognosis is generally poor. If the fusion of a tooth fracture by laser is possible, it will offer an alternative to extraction or at least serve as an adjunctive treatment in the reconstruction. We have tried to use a continuous-wave CO2 laser and a newly developed DP-bioactive glass paste (DPGP) to fuse or bridge tooth crack or fracture lines. Both the DP-bioactive glass paste and tooth enamel have strong absorption bands at the wavelength of 10.6 microm. Therefore, under CO2 laser, DPGP and enamel should have an effective absorption and melt together. The interface between DPGP and enamel could be regarded as a mixture of DPGP and enamel (DPG-E). The study focused on the phase transformation, microstructure, functional group and thermal behavior of DPG-E with or without CO2 laser irradiation, by the analytical techniques of XRD, FTIR, DTA/TGA, and SEM. The results of XRD showed that the main crystal phase in the DPG-E was dicalcium phosphate dihydrate (CaHPO4.2H2O). It changed into CaHPO4, gamma-Ca2P2O7, beta-Ca2P2O7 and finally alpha-Ca2P2O7 with increasing temperature. In the FTIR analysis, the 720 cm(-1) absorption band ascribed to the P-O-P linkage in pyrophosphate rose up and the intensities of the OH- bands reduced after laser irradiation. In regard to the results of DTA/TGA after irradiation, the weight loss decreased due to the removal of part of absorption water and crystallization water by the CO2 laser. SEM micrographs revealed that the melted masses and the plate-like crystals formed a tight chemical bond between the enamel and DPGP. We expect that DPGP with the help of CO2 laser can be an alternative to the treatment of tooth crack or fracture.

Research on industrial 10kW CO2 laser achieves major breakthrough

NASA Astrophysics Data System (ADS)

1991-01-01

The industrial 10kW CO2 laser is one of the items which the industrially developed nations are competing to develop. This laser is capable of continuous output power of over 10kW and can operate continuously for more than 6 hours. The 10kW CO2 laser developed as a key task of China's 7th Five-Year Plan and all its technological targets such as output power, electrooptical conversion efficiency and primary charging continuous operating time, have reached the level of world advancement, allowing China to enter the ranks of international advancement in the area of laser technology. The industrial 10kW CO2 laser can have wide application in such areas of industry as heat treating, machining, welding and surface treatment in industries such as steel, automobiles, ship building and aircraft manufacturing. For instance, using the high-efficiency laser beams of this 10kW laser to treat rollers, fan blades and automotive cylinder blocks can increase the life of these parts and produce large economic benefits. At present, industrial tests of gear welding is already being done on this 10kW laser.

Selected applications of Er:YAG and CO2 lasers for treatment of benign neoplasms and tumorous lesions in the mouth.

PubMed

Błochowiak, Katarzyna; Andrysiak, Piotr; Sidorowicz, Krzysztof; Witmanowski, Henryk; Hędzelek, Wiesław; Sokalski, Jerzy

2015-10-01

Benign neoplasms and hyperplastic tumorous lesions are common oral pathologies. These lesions require to be surgically removed by conventional surgery, laser, or electrosurgery. Surgical treatment aims at complete removal of pathological lesions and ensuring proper healing of the tissues to minimize the risk of lesion recurrence. To present possible applications of Er:YAG and CO2 lasers in removal of benign neoplasms and tumorous lesions developing on oral mucosa as well as to specify indications and limitations of these two methods. Temperature-induced injuries due to laser light application, possibility of post-operative histopathological evaluation of the removed tissue, efficacy of the cut and coagulation, healing process and completeness of laser surgeries give rise to our special concern. The main asset of the CO2 laser comparing to Er:YAG laser is an effective coagulation while thermal injury to the tissues is its limitation, especially with multiple passage of the beam and too high power applied. Er:YAG laser application does not exclude histopathological examination of the removed lesion tissue which is its advantage over CO2 laser. Still, insufficient coagulation is a limitation ofits use in the case of richly vascularized lesions.

Low-power laser treatment of musculoskeletal disorders and body measurements of the equine athlete

NASA Astrophysics Data System (ADS)

Antikas, Theo G.

1990-09-01

This field report presents and analyzes results on 1 cases of rnusculoskeletal disorders of equine athletes treated either with a Soft Laser 632 device (Worldwide Lasers International Geneva) or with an Omega Biotherapy infrared multiprobe multiwavelength device (Omega Labs London). It proposes a codification of low power laser forms of treatment onthefield and suggests modalities of such treatment(s). The therapeutic effects of low power laser beams as well as their postulated modes of action are discussed. Further a new technique utilizing a low power laser device (Technosynthese AG Zurich) for the accurate rnesurement of the height of ponies and horses is described. After testing in over 500 equines the apparatus and the technique were found accurate with an error factor not exceeding 1. 2 mm (1/20 inch) whereas the ancient ''standard stick'' method was found to produce a constant significant error in all animals measured. MATERIALS AND METHODS Soft Laser 632R device: Portable 25 mW heliumneon laser device emitting a visible red band of 632. 8 nm either through a ''window'' or through an optic fiber probe. Omega Biotherapy device: Portable 50 mW infrared laser device with two probes and a multiprobe emitting four wavelength laser bands. Pony_MetreR: Portable heliumneon device with two incorporated nivels and sliding through a rotating ''head'' placed at the top of a tripod that can move on either the vertical (x) or horizontal y) axis. RESULTS

Laser-Induced Graphene Formation on Wood.

PubMed

Ye, Ruquan; Chyan, Yieu; Zhang, Jibo; Li, Yilun; Han, Xiao; Kittrell, Carter; Tour, James M

2017-10-01

Wood as a renewable naturally occurring resource has been the focus of much research and commercial interests in applications ranging from building construction to chemicals production. Here, a facile approach is reported to transform wood into hierarchical porous graphene using CO 2 laser scribing. Studies reveal that the crosslinked lignocellulose structure inherent in wood with higher lignin content is more favorable for the generation of high-quality graphene than wood with lower lignin content. Because of its high electrical conductivity (≈10 Ω per square), graphene patterned on wood surfaces can be readily fabricated into various high-performance devices, such as hydrogen evolution and oxygen evolution electrodes for overall water splitting with high reaction rates at low overpotentials, and supercapacitors for energy storage with high capacitance. The versatility of this technique in formation of multifunctional wood hybrids can inspire both research and industrial interest in the development of wood-derived graphene materials and their nanodevices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Detection of NO sub x,C2H4 concentrations by using CO and CO2 lasers

NASA Technical Reports Server (NTRS)

Gengchen, W.; Qinxin, K.

1986-01-01

A laser, especially the infrared line tunable laser, opens up a new way to monitor the atmospheric environment, and already has gotten effective practical application. One of the most serious problems in open path remote measurement at atmospheric pressure is the broadening effect which leads to increased linewidths, spectral interferences, and, as a result, tends to reduce detection sensitivity, so measuring laser wavelengths should be selected carefully, and interaction between the measuring wavelength and gas to be measured must be known very well. Therefore, N2O, No, NO2, CH4, NH3 and C2H4 absorption properties at some lines of CO and CO2 line tunable lasers were studied. The absorption coefficients of NO, NO2, and C2H4; some results on detection of NO sub x, C2H4 concentrations in both laboratory and field; and selection of measuring wavelengths and error analysis are discussed.

Laser-Material Interactions for Flexible Applications.

PubMed

Joe, Daniel J; Kim, Seungjun; Park, Jung Hwan; Park, Dae Yong; Lee, Han Eol; Im, Tae Hong; Choi, Insung; Ruoff, Rodney S; Lee, Keon Jae

2017-07-01

The use of lasers for industrial, scientific, and medical applications has received an enormous amount of attention due to the advantageous ability of precise parameter control for heat transfer. Laser-beam-induced photothermal heating and reactions can modify nanomaterials such as nanoparticles, nanowires, and two-dimensional materials including graphene, in a controlled manner. There have been numerous efforts to incorporate lasers into advanced electronic processing, especially for inorganic-based flexible electronics. In order to resolve temperature issues with plastic substrates, laser-material processing has been adopted for various applications in flexible electronics including energy devices, processors, displays, and other peripheral electronic components. Here, recent advances in laser-material interactions for inorganic-based flexible applications with regard to both materials and processes are presented. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characterization of the stress and refractive-index distributions in optical fibers and fiber-based devices

NASA Astrophysics Data System (ADS)

Hutsel, Michael R.

2011-07-01

Optical fiber technology continues to advance rapidly as a result of the increasing demands on communication systems and the expanding use of fiber-based sensing. New optical fiber types and fiber-based communications components are required to permit higher data rates, an increased number of channels, and more flexible installation requirements. Fiber-based sensors are continually being developed for a broad range of sensing applications, including environmental, medical, structural, industrial, and military. As optical fibers and fiber-based devices continue to advance, the need to understand their fundamental physical properties increases. The residual-stress distribution (RSD) and the refractive-index distribution (RID) play fundamental roles in the operation and performance of optical fibers. Custom RIDs are used to tailor the transmission properties of fibers used for long-distance transmission and to enable fiber-based devices such as long-period fiber gratings (LPFGs). The introduction and modification of RSDs enable specialty fibers, such as polarization-maintaining fiber, and contribute to the operation of fiber-based devices. Furthermore, the RSD and the RID are inherently linked through the photoelastic effect. Therefore, both the RSD and the RID need to be characterized because these fundamental properties are coupled and affect the fabrication, operation, and performance of fibers and fiber-based devices. To characterize effectively the physical properties of optical fibers, the RSD and the RID must be measured without perturbing or destroying the optical fiber. Furthermore, the techniques used must not be limited in detecting small variations and asymmetries in all directions through the fiber. Finally, the RSD and the RID must be characterized concurrently without moving the fiber to enable the analysis of the relationship between the RSD and the RID. Although many techniques exist for characterizing the residual stress and the refractive index in optical fibers, there is no existing methodology that meets all of these requirements. Therefore, the primary objective of the research presented in this thesis was to provide a methodology that is capable of characterizing concurrently the three-dimensional RSD and RID in optical fibers and fiber-based devices. This research represents a detailed study of the requirements for characterizing optical fibers and how these requirements are met through appropriate data analysis and experimental apparatus design and implementation. To validate the developed methodology, the secondary objective of this research was to characterize both unperturbed and modified optical fibers. The RSD and the RID were measured in a standard telecommunications-grade optical fiber, Corning SMF-28. The effects of cleaving this fiber were also analyzed and the longitudinal variations that result from cleaving were explored for the first time. The fabrication of carbon-dioxide-laser-induced (CO2 -laser-induced) LPFGs was also examined. These devices provide many of the functionalities required for fiber-based communications components as well as fiber-based sensors, and they offer relaxed fabrication requirements when compared to LPFGs fabricated by other methods. The developed methodology was used to perform the first measurements of the changes that occur in the RSD and the RID during LPFG fabrication. The analysis of these measurements ties together many of the existing theories of CO2-laser-induced LPFG fabrication to present a more coherent understanding of the processes that occur. In addition, new evidence provides detailed information on the functional form of the RSD and the RID in LPFGs. This information is crucial for the modeling of LPFG behavior, for the design of LPFGs for specific applications, for the tailoring of fabrication parameters to meet design requirements, and for understanding the limitations of LPFG fabrication in commercial optical fibers. Future areas of research concerning the improvement of the developed methodology, the need to characterize other fibers and fiber-based devices, and the characterization of CO2-laser-induced LPFGs are identified and discussed.

Laser Sounder for Global Measurement of CO2 Concentrations in the Troposphere from Space: Progress

NASA Technical Reports Server (NTRS)

Abshire, J. B.; Krainak, M.; Riris, H. J.; Sun, X.; Riris, H.; Andrews, A. E.; Collatz, J.

2004-01-01

We describe progress toward developing a laser-based technique for the remote measurement of the tropospheric CO2 concentrations from orbit. Our goal is to demonstrate a lidar technique and instrument technology that will permit measurements of the CO2 column abundance in the lower troposphere from aircraft at the few ppm level, with a capability of scaling to permit global CO2 measurements from orbit. Accurate measurements of the tropospheric CO2 mixing ratio from space are challenging due to the many potential error sources. These include possible interference from other trace gas species, the effects of temperature, clouds, aerosols & turbulence in the path, changes in surface reflectivity, and variability in dry air density caused by changes in atmospheric pressure, water vapor and topographic height. Some potential instrumental errors include frequency drifts in the transmitter, small transmission and sensitivity drifts in the instrument. High signal-to-noise ratios and measurement stability are needed for mixing ratio estimates at the few ppm level. We have been developing a laser sounder approach as a candidate for a future space mission. It utilizes multiple different laser transmitters to permit simultaneous measurement of CO2 and O2 extinction, and aerosol backscatter in the same measurement path. It directs the narrow co-aligned laser beams from the instrument's fiber lasers toward nadir, and measures the energy of the strong laser echoes reflected from the Earth's land and water surfaces. During the measurement its narrow linewidth lasers are rapidly tuned on- and off- selected CO2 line near 1572 nm and an O2 absorption line near 770 nm. The receiver measures the energies of the laser echoes from the surface and any clouds and aerosols in the path with photon counting detectors. Ratioing the on- to off-line echo pulse energies for each gas permits the column extinction and column densities of CO2 and O2 to be estimated simultaneously via the differential absorption lidar technique. For the on-line wavelengths, the side of the selected absorption lines are used, which due to pressure broadening, weights the measurements to the lower troposphere, where CO2 variations caused by surface sources and sinks are largest. Simultaneous measurements of O2 column abundance are made using an identical approach using an O2 line. The laser backscatter profiles from clouds and aerosols are measured with other lidar channels, which permits identifying measurements influenced by clouds and/or aerosol scattering in the path. For space use, our lidar would continuously measure at nadir in near polar circular orbit. Using dawn and dusk measurements made over the same region will make it possible to sample the diurnal variations in CO2 mixing ratios. A 1-m diameter telescope is used for the receiver for all wavelengths. When averaging over 50 seconds, our calculations show a SNR of approximately 1500 is achievable for each gas at each on- and off-line measurement. Measurements from such a mission can be used to generate monthly global maps of the lower tropospheric CO2 column abundance. Our calculations show global coverage with an accuracy of a few ppm with a spatial resolution of approximately 50,000 sq. km are achievable each month. We have demonstrated some key elements of the laser, detector and receiver approaches in the laboratory and with measurements over a 206 m horizontal path. These include stable measurements of CO2 line shapes in an absorption cell using a fiber laser amplifier seeded by a tunable diode laser, measurement of small amplitude changes at low optical signal levels with the PMT receiver, and comparison of the horizontal path measurements of CO2 against those from an in-situ instrument.

Parameter optimization for selective laser melting of TiAl6V4 alloy by CO2 laser

NASA Astrophysics Data System (ADS)

Baitimerov, R. M.; Lykov, P. A.; Radionova, L. V.; Safonov, E. V.

2017-10-01

TiAl6V4 alloy is one of the widely used materials in powder bed fusion additive manufacturing technologies. In recent years selective laser melting (SLM) of TiAl6V4 alloy by fiber laser has been well studied, but SLM by CO2-lasers has not. SLM of TiAl6V4 powder by CO2-laser was studied in this paper. Nine 10×10×10 mm cubic specimens were fabricated using different SLM process parameters. All of the fabricated specimens have a good dense structure and a good surface finish quality without dimensional distortion. The lowest porosity that was achieved was about 0.5%.

Magnetic-Field-Assisted Terahertz Quantum Cascade Laser Operating up to 225 K

NASA Technical Reports Server (NTRS)

Wade, A.; Fedorov, G.; Smirnov, D.; Kumar, S.; Williams, B. S.; Hu, Q.; Reno, J. L.

2008-01-01

Advances in semiconductor bandgap engineering have resulted in the recent development of the terahertz quantum cascade laser1. These compact optoelectronic devices now operate in the frequency range 1.2-5 THz, although cryogenic cooling is still required2.3. Further progress towards the realization of devices operating at higher temperatures and emitting at longer wavelengths (sub-terahertz quantum cascade lasers) is difficult because it requires maintaining a population inversion between closely spaced electronic sub-bands (1 THz approx. equals 4 meV). Here, we demonstrate a magnetic-field-assisted quantum cascade laser based on the resonant-phonon design. By applying appropriate electrical bias and strong magnetic fields above 16 T, it is possible to achieve laser emission from a single device over a wide range of frequencies (0.68-3.33 THz). Owing to the suppression of inter-landau-level non-radiative scattering, the device shows magnetic field assisted laser action at 1 THz at temperatures up to 215 K, and 3 THz lasing up to 225 K.

Development of new type of nozzle for high-power Nd:YAG laser welding

NASA Astrophysics Data System (ADS)

Yoshikawa, Mitsuaki; Kurosawa, Takashi; Tanno, Yasuo

2000-02-01

We have been engaged in research and development concerning high power Nd:YAG laser equipment and overall application technology for welding, cutting and drilling. Especially, development of the technology and the system are required for to establish stable welding process. Higher the laser power used, the more laser beam interacted with material, leading to increased vapor, plume and spatter ejection from molten metal. They contaminate and damage the optical systems that are constructed by lens and cover glass plate. In general, in order to protect the optical system, shielding gas flow rate is controlled. But if the gas flow rate exceeds the proper value, molten metal does not protect from oxidation. Therefore we developed a new type co-axial nozzle device. We welded various material (mild steel, stainless steel and aluminum alloy) using new type nozzle and 4 kW YAG laser (MW4000). As the results of experiment, it was cleared that we can weld, within the speed range from 25 mm/min to 2 m/min, stably and easily.

High output power of differently cut Nd:MgO:LiTaO3 CW lasers

NASA Astrophysics Data System (ADS)

Sun, D. H.; Liu, S. D.; Wang, D. Z.; Sang, Y. H.; Kang, X. L.; Liu, H.; Bi, Y.; Yan, B. X.; He, J. L.; Wang, J. Y.

2013-04-01

A high-quality Nd3+ and Mg2+ co-doped LiTaO3 (Nd:MgO:LT) crystal was grown by the Czochralski method. The polarized absorption spectra and fluorescence spectra were studied, and the absorption cross section was calculated by Judd-Ofelt (J-O) theory. The laser performance with different sample cuts of the crystal was investigated for the first time, and it was found that Nd:MgO:LT crystal with different cutting directions (a and c) exhibits different laser properties. By optimizing a partial reflectivity mirror in the laser experimental setting, a high continuous wave output power of 3.58 W was obtained at 1092 and 1076 nm with an optical-to-optical conversion efficiency of 22.78% and slope efficiency of 26.06%. The results indicate that Nd:MgO:LT crystal is a promising candidate for the manufacture of Nd3+ doped periodically poled MgO:LiTaO3 crystal (Nd:PPMgOLT), which should have considerable applications in self-frequency doubling and optical parametric oscillation laser devices.

[The use of lasers in dermatology].

PubMed

Lecocq, C; Pirard, D; del Marmol, V; Berlingin, E

2013-01-01

Albert Einstein is undoubtedly the father of lasers. But it is not until 1964 that the first dermatological lasers were introduced. The Nd-YAG laser, the CO2 laser were developed by Kumar Patel. In a 40 year period lasers not only were diversified but have also become safer and miniaturized. This article hopes to strengthen general practionners' and specialist's knowledge of the different categories of available lasers. The most frequently used ones are ablative lasers (CO2-Erbium), vascular lasers (Nd-YAG, KTP, pulsed dye laser) and the pigment lasers (Q-Switched Nd-YAG, Alexandrite). A description of these lasers and their indications in dermatology will be discussed.

Biochemical Studies Of The Effect Of Two Laser Radiation Wavelengths On The Khapra Beetle Trogoderma Granarium Everts (Coleoptera : Dermestidae)

NASA Astrophysics Data System (ADS)

Abdel-Kader, Mahmoud H.; El-Nozahy, Adel M.; Ahmed, Salwa M. S.; Khalifa, Ibtesam A.

2007-02-01

The present work was carried out to evaluate the actual effect of subleathal dosage of LD30 of two different lasers (Argon-ion and CO2 lasers) on the main metabolites, phosphatases enzymes, transaminases, acetylcholinestrase and peroxidases in the one day adult stage of Trogoderma granarium treated as 2-3 days old pupae. Our results clearly indicated that two different wavelengths of laser radiation increased significantly the total proteins content, whereas no significant changes occurred in the total lipids for the two laser radiation wavelenghts. On the other hand the total carbohydrates were significantly decreased when irradiating using CO2 laser wavelength which is not the case for the Argon-ion laser radiation. Significant changes of phosphatases occurred for both wavelengths. Inhibition of transaminases GOT (glutamic oxaloacetic transaminases) and insignificant changes of GPT (glutamic pyruvic oxaloacetic transaminases) was observed for both laser wavelengths. Significant inhibition of acetyl cholinestrase was observed using CO2 laser and insignificant changes were recorded for Argon ion laser radiation where as insignificant decrease of peroxideses was observed for both lasers.

Acquired acid resistance of human enamel treated with laser (Er:YAG laser and Co2 laser) and acidulated phosphate fluoride treatment: An in vitro atomic emission spectrometry analysis

PubMed Central

Mathew, Anju; Reddy, N. Venugopal; Sugumaran, D. K.; Peter, Joby; Shameer, M.; Dauravu, Liju Marcely

2013-01-01

Background: Dental caries is essentially a process of diffusion and dissolution. If the aspect of dissolution can be curtailed some degree of prevention can be achieved. Aims: The present study was carried out to evaluate and compare the effect of Er:YAG laser and Co2 laser irradiation combined with acidulated phosphate fluoride treatment on in vitro acid resistance of human enamel. Design: An in vitro study was carried out on 30 human premolars to evaluate the enamel's acid resistance using an atomic emission spectrometry analysis. Materials and Methods: A total of 60 enamel specimens were prepared from 30 human premolars and were randomly assigned to 6 groups: (1) Untreated (control); (2) 1.23% acidulated phosphate fluoride (APF) gel application alone for 4 min; (3) Er:YAG laser treatment alone; (4) Co2 laser treatment alone; (5) Er:YAG laser + APF gel application; (6) Co2 laser + APF gel application. The specimens were then individually immersed in 5 ml of acetate buffer solution (0.1 mol/L, pH 4.5) and incubated at 37°C for 24 h, and the acid resistance was evaluated by determining the calcium ion concentration using the atomic emission spectrometry. Statistical Analysis: An ANOVA model was constructed (P value of 0.05), followed by Tukey's test for multiple pair wise comparisons of mean values. Results: Significant differences were found between the control group and the test groups (P < 0.001). Conclusions: Combining acidulated phosphate fluoride with either Er:YAG or Co2 laser had a synergistic effect in decreasing the enamel demineralization more than either fluoride treatment or laser treatment alone. PMID:24015004

Simultaneous sensing of temperature, CO, and CO2 in a scramjet combustor using quantum cascade laser absorption spectroscopy

NASA Astrophysics Data System (ADS)

Spearrin, R. M.; Goldenstein, C. S.; Schultz, I. A.; Jeffries, J. B.; Hanson, R. K.

2014-07-01

A mid-infrared laser absorption sensor was developed for gas temperature and carbon oxide (CO, CO2) concentrations in high-enthalpy, hydrocarbon combustion flows. This diagnostic enables non-intrusive, in situ measurements in harsh environments produced by hypersonic propulsion ground test facilities. The sensing system utilizes tunable quantum cascade lasers capable of probing the fundamental mid-infrared absorption bands of CO and CO2 in the 4-5 µm wavelength domain. A scanned-wavelength direct absorption technique was employed with two lasers, one dedicated to each species, free-space fiber-coupled using a bifurcated hollow-core fiber for remote light delivery on a single line of sight. Scanned-wavelength modulation spectroscopy with second-harmonic detection was utilized to extend the dynamic range of the CO measurement. The diagnostic was field-tested on a direct-connect scramjet combustor for ethylene-air combustion. Simultaneous, laser-based measurements of carbon monoxide and carbon dioxide provide a basis for evaluating combustion completion or efficiency with temporal and spatial resolution in practical hydrocarbon-fueled engines.

Thoracoscopic CO laser coagulation shrinkage of blebs in treatment of spontaneous pneumothorax

NASA Astrophysics Data System (ADS)

Sensaki, Koji; Arai, Tsunenori; Kikuchi, Keiichi; Takagi, Keigo; Tanaka, Susumu; Kikuchi, Makoto

1992-06-01

Spontaneous pneumothorax is a common disease in young people. Operative intervention has been done in most of the recurrent cases. Recently thoracoscopic treatment has been tested as a less invasive treatment modarity. We adopted carbon monoxide (CO) laser for thoracoscopic treatment of recurrent spontaneous pneumothorax. CO laser (wavelength; 5.4 micrometers ) could be delivered by chalcogenide glass (As - S) covered with a teflon sheath and ZnSe fiber tip. The sterilized flexible bronchoscope was inserted through the thoracoscopic outer sheath under local anesthesia. Shrinkage of blebs was obtained by non-contact method of CO laser irradiation. Laser power at the tip was 2.5 - 5 W and irradiation duration was 0.5 s each. Excellent shrinkage of bleb and bulla could be obtained by CO laser without perforation complication. Advantages of CO laser as a thoracoscopic treatment were: (1) capability of fiber delivery (flexible thoracoscopy was easy to operate and clear to visualize the blebs which were frequently found at the apical portion of the lung, and (2) shallow extinction length (good shrinkage of blebs, low risk of perforation, and thin layer of carbonization). In conclusion, our new technique of thoracoscopic CO laser irradiation was found to be a safe and effective treatment of spontaneous pneumothorax.

Successful Treatment of Keloid With Fractionated Carbon Dioxide (CO2) Laser and Laser-Assisted Drug Delivery of Triamcinolone Acetonide Ointment in an African-American Man.

PubMed

Kraeva, Ekaterina; Ho, Derek; Jagdeo, Jared

2017-09-01

Keloids are fibrous growths that occur as a result of abnormal response to dermal injury. Keloids are cosmetically disfiguring and may impair function, often resulting in decreased patient quality-of-life. Treatment of keloids remains challenging, and rate of recurrence is high. We present a case of a 39-year-old African-American man (Fitzpatrick VI) with a 10-year history of keloid, who was successfully treated with eight sessions of fractionated carbon dioxide (CO2) laser immediately followed by laser-assisted drug delivery (LADD) of topical triamcinolone acetonide (TAC) ointment and review the medical literature on fractionated CO2 laser treatment of keloids. To the best of our knowledge, this is the first report of successful treatment of a keloid using combination therapy of fractionated CO2 laser and LADD with topical TAC ointment in an African-American man (Fitzpatrick VI) with excellent cosmetic results sustained at 22 months post-treatment. We believe that this combination treatment modality may be safe and efficacious for keloids in skin of color (Fitzpatrick IV-VI) and other patients. This case highlights the ability of laser surgeons to safely use fractionated CO2 lasers in patients of all skin colors.

J Drugs Dermatol. 2017;16(9):925-927.

Laser versus cold instruments for microlaryngoscopic surgery.

PubMed

Zeitels, S M

1996-05-01

Controversy has arisen concerning the merits of the CO2 laser in microlaryngoscopic surgery because of the potentially harmful effects that the injudicious application of the laser could have on voice production. In an effort to develop a logical approach to instrument selection, the author examined the use of both cold instruments and the CO2 laser in the treatment of various benign and malignant lesions. A retrospective review of 307 microlaryngeal procedures performed over a 3-year period revealed that 263 (86%) were glottal and 44 (14%) were supraglottal. Of the 263 glottal procedures, 203 (77%) employed cold instruments alone and 60 (23%) used both cold instruments and the CO2 laser. The laser was used to assist in all 44 supraglottal procedures. Therefore, 203 (66%) of 307 procedures were done with cold instruments alone, and 104 (34%) of 307 procedures were performed using the CO2 laser with cold instruments. Lesions were stratified on the basis of pathology and size, as well as surgical approach. A primary phonomicrosurgical principle in glottal surgery is to maximally preserve the vocal fold's layered microstructure (laminae propria and epithelium). Precise tangential dissection was necessary for achieving this goal. For limited lesions, this dissection was best accomplished with cold instruments alone. The CO2 laser facilitated hemostatic surgical dissection for all supraglottal lesions and for selected larger glottal lesions in which bleeding would obscure visualization of the microanatomy of the musculomembranous vocal fold.

Direct Bandgap Group IV Materials

DTIC Science & Technology

2016-01-21

devices. In this project, we have accomplished (a) direct bandgap group IV materials of GeSn, (b) GeSn-based planar light - emitting diode operated at near...devices of planar light emitting diode , detector and laser ” 6/12/2015 PI and Co-PI information: - Name of Principal Investigators: Prof. H. H. Cheng...IV materials of GeSn, (b) GeSn-based planar light - emitting diode operated at near infrared with direct emission, and (c) the first planar

In vitro histological evaluation of the surgical margins made by different laser wavelengths in tongue tissues

PubMed Central

Azevedo, Ana-Salvaterra; Ferreira, Fernando; Delgado, Maria-Leonor; Garcês, Fernanda; Carreira, Sofia; Martins, Marco; Suarez-Quintanilla, Juan

2016-01-01

Background Lasers have become standard tools for the surgical treatment of oral lesions. The purpose of this study is to determine the surgical margins and histologically evaluate the tissue thermal effects induced by different types of surgical instruments. Material and Methods Cuts were made in pork tongues’ mucosa with different lasers (Er:YAG at 2W with and without air / water spray and at 4W with and without air / water spray; CO2 at 3.5W and 7W in pulsed mode and at 7W in continuous mode; the diode laser at 3.5W and boost 3.5W in pulsed mode; Nd:YAG at 6W, 40Hz and electroscalpel at 5W and conventional scalpel as control. Macroscopic and microscopic morphological changes were evaluated. Results The results of this study showed that the surgical instruments that caused greater tissue damage extension were: the Nd:YAG laser (670.68μm), the diode 3.5W and boost PW (626.82μm), the CO2 7W CW (571.18μm), the CO2 at 7W PW (485.45μm), the diode 3.5W PW (456.15μm), the electroscalpel (409.57μm) and lastly the CO2 laser 3.5W PW (306.19μm) and Er:YAG (74.66μm) laser, regardless of power, mode or air / water spray used. An association between the Tissue Damage Extension and the Degree of Carbonization (r = 0.789; P = 0.01), and an association between the Tissue Damage Extension and Regularity of the Incision were found (r = -, 299; P = 0.01). Conclusions The results of this study suggest that lasers can be used in soft tissues biopsies of the oral cavity, enabling a correct histopathological analysis, as long as the biological effects of each laser type are considered. The Er:YAG laser revealed its potential for biopsies of the oral mucosa ensuring a successful histological evaluation and the CO2 laser at 3,5W in pulsed mode presented itself as the best choice for surgeries with hemostasis. Key words:CO2 laser, diode laser, Er:YAG laser, laser surgery, Nd:YAG laser, oral mucosa, thermal effect. PMID:27703606

Usefulness of the infrared heterodyne radiometer in remote sensing of atmospheric pollutants.

NASA Technical Reports Server (NTRS)

Menzies, R. T.; Shumate, M. S.

1971-01-01

The application of narrow-band optical receivers to the problem of sensing atmospheric pollution is discussed. The emission/absorption lines of many major atmospheric pollutant molecules overlap the operating frequency bands of CO2 laser and CO laser heterodyne receivers. Several remote pollution sensing systems which are based upon utilization of these spectral overlaps are described, and an analysis of their potential is presented. The possibility of using other lasers (e.g.: the PbSnTe tunable diode laser) as local oscillators is also considered. Results of laboratory experiments with a CO2 laser heterodyne radiometer are presented.

CO2 laser increases the regenerative capacity of human adipose-derived stem cells by a mechanism involving the redox state and enhanced secretion of pro-angiogenic molecules.

PubMed

Constantin, Alina; Dumitrescu, Madalina; Mihai Corotchi, Maria Cristina; Jianu, Dana; Simionescu, Maya

2017-01-01

CO 2 laser has a beneficial effect on stem cells by mechanisms that are not clearly elucidated. We hypothesize that the effect of fractional CO 2 laser on human adipose-derived stem cells (ADSC) could be due to changes in redox homeostasis and secretion of factors contributing to cellular proliferation and angiogenic potential. ADSC incubated in medium containing 0.5 or 10 % FBS were exposed to a single irradiation of a 10,600-nm fractional CO 2 laser; non-irradiated ADSC were used as control. Viability/proliferation of ADSC was assessed by MTT assay; the intracellular reactive oxygen species (ROS) levels and the mitochondrial membrane potential (∆Ψ m ) were determined with DCFH-DA and JC-1 fluorescent probes, respectively. Molecules secreted by ADSC in the medium were determined by ELISA assay, and their capacity to support endothelial tube-like formation by the Matrigel assay. The results showed that compared to controls, ADSC kept in low FBS medium and irradiated with CO 2 laser at 9 W exhibited: (a) increased proliferation (∼20 %), (b) transient increase of mitochondrial ROS and the capacity to restore Δψ m after rotenone induced depolarization, and (c) augmented secretion in the conditioned medium of MMP-2 (twofold), MMP-9 (eightfold), VEGF (twofold), and adiponectin (∼50 %) that have the capacity to support angiogenesis of endothelial progenitor cells. In conclusion, the mechanisms underlying the benefic effect of CO 2 laser on ADSC are the activation of the redox pathways which increases cell proliferation and enhances secretion of angiogenic molecules. These results explain, in part, the mechanisms involved in the increased regenerative potential of CO 2 laser-exposed ADSC that could be exploited for clinical applications.

Raman spectroscopy differentiates squamous cell carcinoma (SCC) from normal skin following treatment with a high-powered CO2 laser.

PubMed

Fox, Sara A; Shanblatt, Ashley A; Beckman, Hugh; Strasswimmer, John; Terentis, Andrew C

2014-12-01

The number of cases of non-melanoma skin cancer (NMSC), which include squamous cell carcinoma (SCC) and basal cell carcinoma (BCC), continues to rise as the aging population grows. Mohs micrographic surgery has become the treatment of choice in many cases but is not always necessary or feasible. Ablation with a high-powered CO2 laser offers the advantage of highly precise, hemostatic tissue removal. However, confirmation of complete cancer removal following ablation is difficult. In this study we tested for the first time the feasibility of using Raman spectroscopy as an in situ diagnostic method to differentiate NMSC from normal tissue following partial ablation with a high-powered CO2 laser. Twenty-five tissue samples were obtained from eleven patients undergoing Mohs micrographic surgery to remove NMSC tumors. Laser treatment was performed with a SmartXide DOT Fractional CO2 Laser (DEKA Laser Technologies, Inc.) emitting a wavelength of 10.6 μm. Treatment levels ranged from 20 mJ to 1200 mJ total energy delivered per laser treatment spot (350 μm spot size). Raman spectra were collected from both untreated and CO2 laser-treated samples using a 785 nm diode laser. Principal Component Analysis (PCA) and Binary Logistic Regression (LR) were used to classify spectra as originating from either normal or NMSC tissue, and from treated or untreated tissue. Partial laser ablation did not adversely affect the ability of Raman spectroscopy to differentiate normal from cancerous residual tissue, with the spectral classification model correctly identifying SCC tissue with 95% sensitivity and 100% specificity following partial laser ablation, compared with 92% sensitivity and 60% selectivity for untreated NMSC tissue. The main biochemical difference identified between normal and NMSC tissue was high levels of collagen in the normal tissue, which was lacking in the NMSC tissue. The feasibility of a combined high-powered CO2 laser ablation, Raman diagnostic procedure for the treatment of NMSC is demonstrated since CO2 laser treatment does not hinder the ability of Raman spectroscopy to differentiate normal from diseased tissue. This combined approach could be employed clinically to greatly enhance the speed and effectiveness of NMSC treatment in many cases. © 2014 Wiley Periodicals, Inc.

BIB mixers

NASA Technical Reports Server (NTRS)

1995-01-01

We have determined that the multi-pin 'microprocessor style' packages in which current Blocked Impurity Band (BIB) devices are mounted will not meet our IF bandwidth spec of greater than 2 GHz for a practical mixer. Hence we have started to repackage the Ga:Ge BIB devices in new microwave compatible packages. The smaller size of the microwave package mount necessitates cutting the BIB array down to include only the 3 smallest detectors: 0.2, 0.4, and 0.6 mm sq. A FIR beam incident at f/1.5 can be focussed on the smallest element for wavelengths shorter than 100 microns. A more typical (easier) beam convergence of f/3 will require 0.4 mm elements at 100 microns and 0.6 mm elements at 170 microns wavelength. Since the device capacitance (parasitic loss) scales with detector size, there is a tradeoff of speed of response and optical convenience. Our existing optics produce only the slower convergence beam, so we need to redesign the optical layout and are looking at long focal length all-reflective microscope objectives. BIB detectors and the edge-coupled microbolometers have restricted IF bandwidths, an order of magnitude less than what is possible with the Schottky-diode mixers we currently use for astronomical observations. Consequently the frequencies of the FIR laser lines must be close to the astronomical line of interest to be an effective Local Oscillator (LO). We have therefore begun a coordinated effort to discover and measure new FIR laser transition lines in close frequency coincidence with important astrophysical lines. Most of this effort involves pumping isotopic variants of known good laser molecules with laser lines from isotopic variants of CO2. We have been most successful in detecting new FIR lines in deuterated ammonia. One line in particular is very close to the frequency of HD rotational line at 2675 GHz.

Treatment of striae distensae with needling therapy versus CO2 fractional laser.

PubMed

Khater, Mohamed H; Khattab, Fathia M; Abdelhaleem, Manal R

2016-01-01

Striae are atrophic dermal scars with overlying epidermal atrophy causing cosmetic concern. This study assesses and compares the efficacy and safety of needling therapy versus CO2 fractional laser in treatment of striae. Twenty Egyptian female patients with striae in the abdomen and lower limbs were involved in the study. The patients were treated with needling therapy and CO2 laser every 1 month for 3 sessions. Follow-up by digital photography and skin biopsy was conducted at baseline and 6 months after treatment. Clinical improvement was assessed by comparing photographs and patient's satisfaction before and after treatment. Nine of 10 (90%) needle-treated patients showed improvement. Among them, 3 (30%) had good, 4 (40%) had fair, and 2 (20%) had poor improvements; however, 1 (10%) did not show any improvement after the treatment. In CO2-laser treated patients, 5 of 10 (50%) of the patients showed clinical improvement; 1 (10%) were good, 3 (30%) were fair, and 1 (10%) were poor; however, 5 (50%) did not show improvement. The results support the use of microneedle therapy over CO2 lasers for striae treatment.

"One-shot" CO2 versus Er:YAG laser stapedotomy: is the outcome the same?

PubMed

Marchese, Maria Raffaella; Scorpecci, Alessandro; Cianfrone, Francesca; Paludetti, Gaetano

2011-03-01

To assess and compare the functional results obtained by means of multiple-shot Erbium: yttrium-aluminum-garnet (Er:YAG) laser to those obtained using "one-shot" CO(2) laser stapedotomy in patients affected by otosclerosis. A retrospective case review was performed. Of the total number of 123 patients (114 ears) who underwent primary small-fenestra stapedotomy from January 2006 to September 2008, seven patients who received multiple-shot laser CO(2) stapedotomy were excluded from the study. The remaining 116 patients (104 ears) were sorted, and "one-shot" CO(2) laser stapedotomy (group A) was performed in 35/104 and Er:YAG laser stapedotomy (group B) in 69/104. After surgery, air conduction-pure tone average (AC-PTA) and air-bone gap (ABG) improved significantly in both groups, whereas sensorineural hearing loss (SNHL) and bone conduction (BC)-PTA did not change in both the groups. In group A, the postoperative ABG was significantly better (12.63 vs. 14.86 dB). Moreover, after "one-shot" stapedotomy, the AC-PTA significantly improved in all tested frequencies. On the contrary, in group B the AC-PTA improved significantly only in two frequencies (0.5 and 1 kHz). Consistent with previous reports, our findings confirm that laser stapedotomy is a safe and effective surgery, regardless of the technique. Based on our functional results, the "one-shot" CO(2) laser technique seems to be associated with a significantly better postoperative ABG if compared to Er:YAG laser stapedotomy.

Early effect of fractional CO2 laser treatment in Post-menopausal women with vaginal atrophy.

PubMed

Eder, Scott Evan

2018-03-31

Fractional CO 2 lasers have been shown to provide improvement of vulvovaginal atrophy (VVA). The aim of the current study was to assess the early effect of a fractional CO 2 laser system in treating postmenopausal women with clinical symptoms of VVA. 28 healthy post-menopausal women (mean age 60.1 ± 5.55 years) with VVA-related symptoms were treated with fractional CO 2 laser 3 times, in 4-week intervals. At each study visit, VHIS score and VVA symptom severity were recorded. Sexual function was assessed with the Female Sexual Function Index (FSFI). One month following the first laser treatment, the mean VHIS score was significantly improved (13.89 ± 4.25 vs. baseline 11.93 ± 3.82; p < 0.05), and improved further at 3 and 6 months following all three laser treatments (16.43 ± 4.20 and 17.46 ± 4.07, respectively). Almost all VVA symptoms were significantly improved at one month following the first treatment. A further significant improvement in VVA symptoms was noted at 3 and 6 months following the third laser treatment. Following treatments, the FSFI score increased significantly (22.36 ± 10.40 vs. baseline 13.78 ± 7.70; p < 0.05), and remained significantly higher than baseline at the 3- and 6-month follow-up visits. CO 2 laser therapy for post-menopausal women can be considered an effective therapeutic option providing relief of symptoms already noted after one laser treatment.

A radiatively pumped CW CO2 laser

NASA Technical Reports Server (NTRS)

Insuik, R. J.; Christiansen, W. H.

1984-01-01

A proof of principle experiment to demonstrate the physics of a radiatively pumped laser has been carried out. For the first time, a blackbody cavity has optically pumped a CW CO2 laser. Results are presented from a series of experiments using mixtures of CO2, He, and Ar in which maximum output power was obtained with a 20 percent CO2-15 percent He-65 percent Ar mixture. The dependence of the output power on the blackbody temperature and the cooling gas flow rate is also discussed. By appropriately varying these parameters, continuous output powers of 8-10 mW have been achieved.

Miniaturized Laser Heterodyne Radiometer for Measurements of CO2 in the Atmospheric Column

NASA Technical Reports Server (NTRS)

Wilson, E. L.; Mclinden, M. L.; Miller, J. H.; Allan, G. R.; Lott, L. E.; Melroy, H. R.; Clarke, G. B.

2013-01-01

We have developed a low-cost, miniaturized laser heterodyne radiometer for highly sensitive measurements of carbon dioxide (CO2) in the atmospheric column. In this passive design, sunlight that has undergone absorption by CO2 in the atmosphere is collected and mixed with continuous wave laser light that is step-scanned across the absorption feature centered at 1,573.6 nm. The resulting radio frequency beat signal is collected as a function of laser wavelength, from which the total column mole fraction can be de-convolved. We are expanding this technique to include methane (CH4) and carbon monoxide (CO), and with minor modifications, this technique can be expanded to include species such as water vapor (H2O) and nitrous oxide (N2O).

The use of pulsed CO2 lasers for the treatment of vulvovaginal atrophy.

PubMed

Salvatore, Stefano; Athanasiou, Stavros; Candiani, Massimo

2015-12-01

This article reviews the literature regarding the safety and efficacy of the use of a pulsed CO2 laser for the treatment of vulvovaginal atrophy (VVA). Prospective observational studies have demonstrated histological changes after the use of pulsed CO2 laser vaginally in atrophic conditions. Increased collagen and extracellular matrix production has been reported together with an increase in the thickness of the vaginal epithelium with the formation of new papilla. Three different observational studies reported a significant improvement of VVA assessed subjectively (with a 10-point visual analogue scale) and objectively (using the Vaginal Health Index) after a cycle of three treatments of pulsed CO2 laser. Also sexual function (assessed with the Female Sexual Function Index) and quality of life (evaluated with the SF12 questionnaire) significantly improved. No complications or side-effects were reported during or after the laser procedure that was performed in an outpatient setting. Increasing evidence with histological and clinical data supports the use of pulsed CO2 lasers in the treatment of VVA; however, no randomized control trial (sham versus treatment) has yet been produced and no data on the duration of therapy are currently available.

Stereotactic CO2 laser therapy for hydrocephalus

NASA Astrophysics Data System (ADS)

Kozodoy-Pins, Rebecca L.; Harrington, James A.; Zazanis, George A.; Nosko, Michael G.; Lehman, Richard M.

1994-05-01

A new fiber-optic delivery system for CO2 radiation has been used to successfully treat non-communicating hydrocephalus. This system consists of a hollow sapphire waveguide employed in the lumen of a stereotactically-guided neuroendoscope. CO2 gas flows through the bore of the hollow waveguide, creating a path for the laser beam through the cerebrospinal fluid (CSF). This delivery system has the advantages of both visualization and guided CO2 laser radiation without the same 4.3 mm diameter scope. Several patients with hydrocephalus were treated with this new system. The laser was used to create a passage in the floor of the ventricle to allow the flow of CSF from the ventricles to the sub-arachnoid space. Initial postoperative results demonstrated a relief of the clinical symptoms. Long-term results will indicate if this type of therapy will be superior to the use of implanted silicone shunts. Since CO2 laser radiation at 10.6 micrometers is strongly absorbed by the water in tissue and CSF, damage to tissue surrounding the lesion with each laser pulse is limited. The accuracy and safety of this technique may prove it to be an advantageous therapy for obstructive hydrocephalus.

Laser applications in meteorology and earth and atmospheric remote sensing; Proceedings of the Meeting, Los Angeles, CA, Jan. 16-18, 1989

NASA Technical Reports Server (NTRS)

Sokoloski, Martin M. (Editor)

1989-01-01

Various papers on laser applications in meteorology and earth and atmospheric remote sensing are presented. The individual topics addressed include: solid state lasers for the mid-IR region, tunable chromium lasers, GaInAsSb/AlGaAsSb injection lasers for remote sensing applications, development and design of an airborne autonomous wavemeter for laser tuning, fabrication of lightweight Si/SiC lidar mirrors, low-cost double heterostructure and quantum-well laser array development, nonlinear optical processes for the mid-IR region, simulated space-based Doppler lidar performance in regions of backscatter inhomogeneities, design of CO2 recombination catalysts for closed-cycle CO2 lasers, density measurements with combined Raman-Rayleigh lidar, geodynamics applications of spaceborne laser ranging, use of aircraft laser ranging data for forest mensuration, remote active spectrometer, multiwavelngth and triple CO2 lidars for trace gas detection, analysis of laser diagnostics in plumes, laser atmospheric wind sounder, compact Doppler lidar system using commercial off-the-shelf components, and preliminary design for a laser atmospheric wind sounder.

Spectral characteristics of quantum-cascade laser operating at 10.6 μm wavelength for a seed application in laser-produced-plasma extreme UV source.

PubMed

Nowak, Krzysztof M; Ohta, Takeshi; Suganuma, Takashi; Yokotsuka, Toshio; Fujimoto, Junichi; Mizoguchi, Hakaru; Endo, Akira

2012-11-15

In this Letter, we investigate, for the first time to our knowledge, the spectral properties of a quantum-cascade laser (QCL) from a point of view of a new application as a laser seeder for a nanosecond-pulse high-repetition frequency CO(2) laser operating at 10.6 μm wavelength. The motivation for this work is a renewed interest in such a pulse format and wavelength driven by a development of extreme UV (EUV) laser-produced-plasma (LPP) sources. These sources use pulsed multikilowatt CO(2) lasers to drive the EUV-emitting plasmas. Basic spectral performance characteristics of a custom-made QCL chip are measured, such as tuning range and chirp rate. The QCL is shown to have all essential qualities of a robust seed source for a high-repetition nanosecond-pulsed CO(2) laser required by EUV LPP sources.

Early treatment using fractional CO2 laser before skin suture during scar revision surgery in Asians.

PubMed

Du, Feiya; Yu, Yusheng; Zhou, Zhiqin; Wang, Liujia; Zheng, Shusen

2018-04-01

Fractional CO 2 laser is one of the most effective treatment options used to resurface scars. However, most previous studies have been performed on mature scars at least 2 months after surgery. Recent studies have emphasized the importance of early treatment to reduce scar formation. In the present study, we described our experience with fractional CO 2 laser intervention before skin suture during scar revision surgery in Asians, and found the treatment was safe and effective.

Laser arthroscopic surgery of the shoulder and knee

NASA Astrophysics Data System (ADS)

Smith, Chadwick F.; Johansen, Ed; Bonvalet, Todd; Sutter, Leroy V., Jr.; Marshall, G. June

1990-06-01

The laser is used less in orthopaedics than in any other medical specialty. Improving technology and the impressive effect of the CO2 laser on orthopaedic tissues has, however, accelerated the interest of orthopaedic surgeons over the past two years. The carbon dioxide laser is now commonly used in orthopaedics for difficult to access lesions of the knee - particularly those of a degenerative nature with high surface area and low volume. The results are presented in this paper and reveal no evidence of lasting complications. Although several types of lasers are being experimentally utilized in orthopaedics, the YAG and CO2 lasers are the only lasers commonly utilized. The YAG laser is utilized for shoulder arthroscopy and offers the advantage of passage of energy through fiber and the ability to utilize the tool in an aqueous environment. It is too early to determine as to whether or not the YAG laser or the CO2 laser will be the most efficient energy delivery system for use in the shoulder.

Residual stress and damage-induced critical fracture on CO2 laser treated fused silica

NASA Astrophysics Data System (ADS)

Matthews, M. J.; Stolken, J. S.; Vignes, R. M.; Norton, M. A.; Yang, S.; Cooke, J. D.; Guss, G. M.; Adams, J. J.

2009-10-01

Localized damage repair and polishing of silica-based optics using mid- and far-IR CO2 lasers has been shown to be an effective method for increasing optical damage threshold in the UV. However, it is known that CO2 laser heating of silicate surfaces can lead to a level of residual stress capable of causing critical fracture either during or after laser treatment. Sufficient control of the surface temperature as a function of time and position is therefore required to limit this residual stress to an acceptable level to avoid critical fracture. In this work we present the results of 351 nm, 3ns Gaussian damage growth experiments within regions of varying residual stress caused by prior CO2 laser exposures. Thermally stressed regions were non-destructively characterized using polarimetry and confocal Raman microscopy to measure the stress induced birefringence and fictive temperature respectively. For 1~40s square pulse CO2 laser exposures created over 0.5-1.25kW/cm2 with a 1-3mm 1/e2 diameter beam (Tmax~1500-3000K), the critical damage site size leading to fracture increases weakly with peak temperature, but shows a stronger dependence on cooling rate, as predicted by finite element hydrodynamics simulations. Confocal micro-Raman was used to probe structural changes to the glass over different thermal histories and indicated a maximum fictive temperature of 1900K for Tmax>=2000K. The effect of cooling rate on fictive temperature caused by CO2 laser heating are consistent with finite element calculations based on a Tool-Narayanaswamy relaxation model.

Impact of CO2 laser and stannous fluoride on primary tooth erosion.

PubMed

Rocha, Cristiane Tomaz; Turssi, Cecilia Pedroso; Rodrigues-Júnior, Antonio Luiz; Corona, Silmara Aparecida Milori

2016-04-01

This study evaluated in vitro the effect of input power of CO2 laser, either associated or not to stannous fluoride (SnF2) gel, for the control of intrinsic erosion in primary teeth. One hundred four enamel slabs (3 × 3 × 2 mm) from human primary molars were flattened and polished. Adhesive tapes were placed on their surface leaving a window of 3 × 1 mm. Slabs were then cycled four times in 0.01 M hydrochloric acid (pH 2, 2 min) and in artificial saliva (2 h) for creation of erosive lesions. Specimens were randomly assigned into eight groups (n = 13) according to fluoride application [absent (control) or 0.4% stannous fluoride gel (SnF2)] and input power of CO2 laser [unlased (control), 0.5, 1.0 or 1.5 W]. The CO2 laser irradiation was performed in an ultra-pulse mode (100 μs of pulse duration), 4-mm working distance, for 10 s. Specimens were then submitted to further erosive episodes for 5 days and evaluated for enamel relative permeability. Fluoride did not show any protective effect for any of the laser-treated groups or control (p = 0.185). However, a significant effect was detected for input power of CO2 laser (p = 0.037). Tukey's test showed that there was a significant statistically difference between specimens irradiated with 0.5 and 1.5 W (p = 0.028). The input power of 0.5 W showed lower permeability. Variation of input power CO2 laser can influence enamel permeability, at the power of 1.5 W which promoted greater permeability.

Design and development of equipment for laser wire stripping

NASA Technical Reports Server (NTRS)

Iceland, W. F.

1977-01-01

Three laser wire strippers have been built for the stripping of Kapton-insulated wire, the baseline wire of the space shuttle orbiter. The strippers are: (1) a bench-model stripper powered with a cw CO2 10.6-micron laser, (2) a hand-held stripper powered with a cw 1.06-micron Nd-YAG laser with an output of 5-7 watts, and (3) a hand-held stripper with a five-inch-long CO2 laser inside the stripping head.

Studies of CW lasing action in CO2-CO, N2O-CO, CO2-H2O, and N2O-H2O mixtures pumped by blackbody radiation

NASA Technical Reports Server (NTRS)

Abel, Robert W.; Christiansen, Walter H.; Li, Jian-Guo

1988-01-01

A proof of principle experiment to evaluate the efficacy of CO and H2O in increasing the power output for N2O and CO2 lasing mixtures has been conducted and theoretically analyzed for a blackbody radiation-pumped laser. The results for N2O-CO, CO2-CO, N2O-H2O and CO2-H2O mixtures are presented. Additions of CO to the N2O lasant increased power up to 28 percent for N2O laser mixtures, whereas additions of CO to the CO2 lasant, and the addition of H2O to both the CO2 and N2O lasants, resulted in decreased output power.

Comparison of fiber delivered CO2 laser and electrocautery in transoral robot assisted tongue base surgery.

PubMed

Karaman, Murat; Gün, Taylan; Temelkuran, Burak; Aynacı, Engin; Kaya, Cem; Tekin, Ahmet Mahmut

2017-05-01

To compare intra-operative and post-operative effectiveness of fiber delivered CO 2 laser to monopolar electrocautery in robot assisted tongue base surgery. Prospective non-randomized clinical study. Twenty moderate to severe obstructive sleep apnea (OSA) patients, non-compliant with Continuous Positive Airway Pressure (CPAP), underwent Transoral Robotic Surgery (TORS) using the Da Vinci surgical robot in our University Hospital. OSA was treated with monopolar electrocautery in 10 patients, and with flexible CO 2 laser fiber in another 10 patients. The following parameters in the two sets are analyzed: Intraoperative bleeding that required cauterization, robot operating time, need for tracheotomy, postoperative self-limiting bleeding, length of hospitalization, duration until start of oral intake, pre-operative and post-operative minimum arterial oxygen saturation, pre-operative and post-operative Epworth Sleepiness Scale score, postoperative airway complication and postoperative pain. Mean follow-up was 12 months. None of the patients required tracheotomy and there were no intraoperative complications related to the use of the robot or the CO 2 laser. The use of CO 2 laser in TORS-assisted tongue base surgery resulted in less intraoperative bleeding that required cauterization, shorter robot operating time, shorter length of hospitalization, shorter duration until start of oral intake and less postoperative pain, when compared to electrocautery. Postoperative apnea-hypopnea index scores showed better efficacy of CO 2 laser than electrocautery. Comparison of postoperative airway complication rates and Epworth sleepiness scale scores were found to be statistically insignificant between the two groups. The use of CO 2 laser in robot assisted tongue base surgery has various intraoperative and post-operative advantages when compared to monopolar electrocautery.

Coherent cavity-enhanced dual-comb spectroscopy

PubMed Central

Fleisher, Adam J.; Long, David A.; Reed, Zachary D.; Hodges, Joseph T.; Plusquellic, David F.

2016-01-01

Dual-comb spectroscopy allows for the rapid, multiplexed acquisition of high-resolution spectra without the need for moving parts or low-resolution dispersive optics. This method of broadband spectroscopy is most often accomplished via tight phase locking of two mode-locked lasers or via sophisticated signal processing algorithms, and therefore, long integration times of phase coherent signals are difficult to achieve. Here we demonstrate an alternative approach to dual-comb spectroscopy using two phase modulator combs originating from a single continuous-wave laser capable of > 2 hours of coherent real-time averaging. The dual combs were generated by driving the phase modulators with step-recovery diodes where each comb consisted of > 250 teeth with 203 MHz spacing and spanned > 50 GHz region in the near-infrared. The step-recovery diodes are passive devices that provide low-phase-noise harmonics for efficient coupling into an enhancement cavity at picowatt optical powers. With this approach, we demonstrate the sensitivity to simultaneously monitor ambient levels of CO2, CO, HDO, and H2O in a single spectral region at a maximum acquisition rate of 150 kHz. Robust, compact, low-cost and widely tunable dual-comb systems could enable a network of distributed multiplexed optical sensors. PMID:27409866

Stable isotope analysis of molecular oxygen from silicates and oxides using CO2 laser extraction

NASA Technical Reports Server (NTRS)

Perry, Eugene

1996-01-01

A laser-excited system for determination of the oxygen isotope composition of small quantities of silicate and oxide minerals was constructed and tested at JSC. This device is the first reported to use a commercially available helium cryostat to transfer and purify oxygen gas quantitatively within the system. The system uses oxygen gas instead of the conventional CO2 for mass spectrometer analyses. This modification of technique permits determination of all three stable oxygen isotopes, an essential requirement for oxygen isotope analysis of meteoritic material. Tests of the system included analysis of standard silicate materials NBS 28 and UWMG2 garnet, six SNC meteorites, and inclusions and chondrules from the Allende meteorite. Calibration with terrestrial standards was excellent. Meteorite values are close to published values and show no evidence of terrestrial oxygen contamination. The one limitation observed is that, in some runs on fine-grained SNC matrix material, sample results were affected by other samples in the sample holder within the reaction chamber. This reemphasizes the need for special precautions in dealing with fine-grained, reactive samples. Performance of the JSC instrument compares favorably with that of any other instrument currently producing published oxygen isotope data.

A multi-wavelength fiber-optic temperature-controlled laser soldering system for upper aerodigestive tract reconstruction: an animal model.

PubMed

Abergel, Avraham; Gabay, Ilan; Fliss, Dan M; Katzir, Abraham; Gil, Ziv

2011-06-01

Laser soldering of a thick multilayer organ using conventional CO(2) lasers is ineffective. The purpose of this work was to develop a method for bonding the multilayer tissue of the upper aerodigestive tracts (UADT) without the need of sutures or stapling. Animal model. Academic research laboratory. The authors developed a multi-wavelength laser system, based on 2 fiber-optic lasers applied simultaneously. A highly absorbable CO(2) laser interacts with the muscular layer, and a nonabsorbable GaAs laser interacts with indocyanine-green solid albumin, placed between the mucosa and the muscular layer. The authors used an ex vivo porcine model to examine the capability of this system to effectively correct esophageal tears. The soldered esophagi burst pressure was >175 cm H(2)O (98% success rate) in 88 of the 90 experiments. A conventional CO(2) laser soldering resulted in insufficient bonding (mean burst pressure of 40 ± 7 cm H(2)O, n = 5), while the multi-wavelength laser system provided an ~9-fold tighter seal (359 ± 75.4 cm H(2)O, P < .0001, n = 15). Burst pressures after conventional suturing of the defect was significantly lower (106 ± 65.8 cm H(2)O, P < .001) than in the multi-wavelength laser system. Bonding of the UADT mucosa using a multi-wavelength, temperature-controlled laser soldering system can support significantly higher pressures then conventional CO(2) laser soldering and suture repair. The mean bonding pressure was 3.5-fold higher than the maximal swallowing pressure. Our findings provide a basis for implementation of new surgical tools for repair of esophageal perforations.

Aspects of CO2 laser engraving of printing cylinders.

PubMed

Atanasov, P A; Maeno, K; Manolov, V P

1999-03-20

Results of the experimental and theoretical investigations of CO(2) laser-engraved cylinders are presented. The processed surfaces of test samples are examined by a phase-stepping laser interferometer, digital microscope, and computer-controlled profilometer. Fourier analysis is made on the patterns parallel to the axis of the laser-scribed test ceramic cylinders. The problem of the visually observed banding is discussed.

Simulation of planetary entry radiative heating with a CO2 gasdynamic laser

NASA Technical Reports Server (NTRS)

Lundell, J. H.; Dickey, R. R.; Howe, J. T.

1975-01-01

Heating encountered during entry into the atmospheres of Jupiter, Saturn, and Uranus is described, followed by a discussion of the use of a CO2 gasdynamic laser to simulate the radiative component of the heating. Operation and performance of the laser is briefly described. Finally, results of laser tests of some candidate heat-shield materials are presented.

Corona Preionization Technique for Carbon Dioxide TEA Lasers.

DTIC Science & Technology

1982-11-30

34’" " " " "- -. .. " "I~ 82R8O701-02 CORONA PREIONIZATION TECHNIQUE FOR CARBON DIOXIDE TEA LASERS W after R. Kamnki SUnited Technologiles Research Center C...TITLE (and Subtitle) S. TYPE OF REPORT a PERIOD COVERED CORONA PREIONIZATION TECHNIQUE FOR CARBON Final Report DIOXIDE TEA LASERS May 5, 1981...Preionization Laser UV Preionization Pulsed CO2 Laser Corona Preionization CO2 TEA Laser 10. ABSTRACT (Continue on reverse side If neceeeiny md Identify

Lasers and wound healing.

PubMed

Nemeth, A J

1993-10-01

The advances in laser surgery over the past decade have been remarkable and have significantly altered the management of a host of dermatologic disorders. This article focuses on the CO2 laser as a cutting and vaporization tool and reviews the features that distinguish CO2 laser-induced wounds from those created by a scalpel. Tissue welding, wound management after skin treatment with the visible light lasers based on the principle of selective photothermolysis, as well as the controversial field of low-energy laser therapy (biostimulation) are also addressed.

Nd:YAG and CO2 laser therapy of oral mucosal lesions.

PubMed

White, J M; Chaudhry, S I; Kudler, J J; Sekandari, N; Schoelch, M L; Silverman, S

1998-12-01

Experiences gained in the management of oral mucosal lesions by CO2 and Nd:YAG laser therapy in an outpatient clinic treated over an 80-year period are described. Lasers have indications for use in dentistry for incision, excision, and coagulation of intraoral soft tissue. Advances in laser technology have provided delivery systems for site-specific delivery of laser energy with short interaction items on tissue to be ablated. This study retrospectively evaluates a series of clinical case studies. Sixty-four patients with a variety of benign oral soft tissue lesions were treated by laser excision. Thirty-five patients were treated by a pulsed fiberoptic delivered Nd:YAG contact laser, and 29 by a continuous free-beam CO2 non-contact laser. The largest group of lesions treated were leukoplakia (39 cases). Other lesions excised and biopsied were lichen planus, squamous papilloma, pyogenic granuloma, focal melanosis, nonhealing traumatic ulceration, hemangioma, and lymphangioma. All patients were followed postoperatively (mean 6.8 months, range 1-36 months). Laser excision was well tolerated by patients with no intraoperative or postoperative adverse effects. All patients healed postsurgically with no loss of function. CO2 and Nd:YAG lasers are successful surgical options when performing excision of benign intraoral lesions. Advantages of laser therapy include minimal postoperative pain, conservative site-specific minimally invasive surgeries, and elimination of need for sutures.

Direct quantitative comparison of molecular responses in photodamaged human skin to fractionated and fully ablative carbon dioxide laser resurfacing.

PubMed

Orringer, Jeffrey S; Sachs, Dana L; Shao, Yuan; Hammerberg, Craig; Cui, Yilei; Voorhees, John J; Fisher, Gary J

2012-10-01

Fractionated ablative laser resurfacing has become a widely used treatment modality. Its clinical results are often found to approach those of traditional fully ablative laser resurfacing. To directly compare the molecular changes that result from fractionated and fully ablative carbon dioxide (CO(2)) laser resurfacing in photodamaged human skin. Photodamaged skin of 34 adult volunteers was focally treated at distinct sites with a fully ablative CO(2) laser and a fractionated CO(2) laser. Serial skin samples were obtained at baseline and several time points after treatment. Real-time reverse transcriptase polymerase chain reaction technology and immunohistochemistry were used to quantify molecular responses to each type of laser treatment. Fully ablative and fractionated CO(2) laser resurfacing induced significant dermal remodeling and collagen induction. After a single treatment, fractionated ablative laser resurfacing resulted in collagen induction that was approximately 40% to 50% as pronounced as that induced by fully ablative laser resurfacing. The fundamental cutaneous responses that result from fully ablative and fractionated carbon dioxide laser resurfacing are similar but differ in magnitude and duration, with the fully ablative procedure inducing relatively greater changes including more pronounced collagen induction. However, the molecular data reported here provide substantial support for fractionated ablative resurfacing as an effective treatment modality for improving skin texture. © 2012 by the American Society for Dermatologic Surgery, Inc. Published by Wiley Periodicals, Inc.

Laser treatment in gynecology

NASA Astrophysics Data System (ADS)

de Riese, Cornelia

2004-07-01

This presentation is designed as a brief overview of laser use in gynecology, for non-medical researchers involved in development of new laser techniques. The literature of the past decade is reviewed. Differences in penetration, absorption, and suitable delivery media for the beams dictate clinical application. The use of CO2 laser in the treatment of uterine cervical intraepithelial lesions is well established and indications as well as techniques have not changed over 30 years. The Cochrane Systematic Review from 2000 suggests no obviously superior technique. CO2 laser ablation of the vagina is also established as a safe treatment modality for VAIN. CO2 laser permits treatment of lesions with excellent cosmetic and functional results. The treatment of heavy menstrual bleeding by destruction of the endometrial lining using various techniques has been the subject of a 2002 Cochran Database Review. Among the compared treatment modalities are newer and modified laser techniques. Conclusion by reviewers is that outcomes and complication profiles of newer techniques compare favorably with the gold standard of endometrial resection. The ELITT diode laser system is one of the new successful additions. CO2 laser is also the dominant laser type used with laparoscopy for ablation of endometriotic implants. Myoma coagulation or myolysis with Nd:Yag laser through the laparoscope or hysteroscope is a conservative treatment option. Even MRI guided percutaneous approaches have been described. No long-term data are available.

Transoral laser microsurgery for laryngeal cancer: A primer and review of laser dosimetry

PubMed Central

Rubinstein, Marc

2010-01-01

Transoral laser microsurgery (TLM) is an emerging technique for the management of laryngeal and other head and neck malignancies. It is increasingly being used in place of traditional open surgery because of lower morbidity and improved organ preservation. Since the surgery is performed from the inside working outward as opposed to working from the outside in, there is less damage to the supporting structures that lie external to the tumor. Coupling the laser to a micromanipulator and a microscope allows precise tissue cutting and hemostasis; thereby improving visualization and precise ablation. The basic approach and principles of performing TLM, the devices currently in use, and the associated dosimetry parameters will be discussed. The benefits of using TLM over conventional surgery, common complications and the different settings used depending on the location of the tumor will also be discussed. Although the CO2 laser is the most versatile and the best-suited laser for TLM applications, a variety of lasers and different parameters are used in the treatment of laryngeal cancer. Improved instrumentation has lead to an increased utilization of TLM by head and neck cancer surgeons and has resulted in improved outcomes. Laser energy levels and spot size are adjusted to vary the precision of cutting and amount of hemostasis obtained. PMID:20835840

Laser Sounder for Measuring Atmospheric CO2 Concentrations: Progress Toward Ascends

NASA Technical Reports Server (NTRS)

Abshire, J. B.; Kawa, S. R.; Riris, H.; Allan, G. R.; Sun, X.; Stephen, M. A.; Wilson, E.; Burris, J. F.; Mao, J.

2008-01-01

The next generation of space-based, active remote sensing instruments for measurement of tropospheric CO2 promises a capability to quantify global carbon sources and sinks at regional scales. Active (laser) methods will extend CO2 measurement coverage in time, space, and perhaps precision such that the underlying mechanisms for carbon exchange at the surface can be understood with .sufficient detail to confidently project the future of carbon-climate interaction and the influence of remediative policy actions. The recent Decadal Survey for Earth Science by the US National Research Council has recommended such a mission called the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) for launch in 2013-2016. We have been developing a laser technique for measurement of tropospheric CO2 for a number of years. Our immediate goal is to develop and demonstrate the method and instrument technology that will permit measurements of the CO2 column abundance over a horizontal path and from aircraft at the few-ppmv level. Our longer-term goal is to demonstrate the required capabilities of the technique, develop a space mission approach, and design the instrument for an ASCENDS-type mission. Our approach is to use a dual channel laser absorption spectrometer (i.e., differential absorption in altimeter mode), which continuously measures from a near-polar circular orbit. We use several co-aligned tunable fiber laser transmitters allowing simultaneous measurement of the absorption from a CO2 line in the 1570 nm band, O2 extinction in the oxygen A-band (near 765 nm), and aerosol backscatter in the same measurement path. We measure the energy of the laser echoes at nadir reflected from land and water surfaces, day and night. The lasers have spectral widths much narrower than the gas absorption lines and are turned on and off the selected CO2 and O2 lines at kHz rates. The gas extinction and column densities for the CO2 and O2 gases are estimated from the ratio of the on and off-line singnals via the DIAL technique. We used pulsed laser signals, photon counting detectors, and time gating to isolate the laser returns from the surface, and to reject photons scattered from thin clouds and aerosols. High signal-to-noise ratios are required and the CO2 estimates can be sensitive to small drifts or other errors in the instrument, so the absorption estimates need to be quite stable for hours. We have constructed a breadboard version of the CO2 sensor that uses a low power fiber laser and a 20 cm diameter telescope. We have used it to make measurements of CO2 absorption in the laboratory and over 200-m to 2-km long open horizontal paths. These have been done in several sessions extending over multiple days, which allows us to assess the measurement stability and to compare absorption variations to readings from an external in situ CO2 sensor. We have also calculated characteristics of the technique for space including its expected measurement performance for different modulation types, and have performed an initial space mission accommodation study. We sill describe these results in the presentation.

Effect of CO2 Laser and Fluoride Varnish Application on Microhardness of Enamel Surface Around Orthodontic Brackets

PubMed Central

Mahmoudzadeh, Majid; Rezaei-Soufi, Loghman; Farhadian, Nasrin; Jamalian, Seyed Farzad; Akbarzadeh, Mahdi; Momeni, Mohammadali; Basamtabar, Masome

2018-01-01

Introduction: Orthodontic treatment has many advantages such as esthetic improvement and self-esteem enhancement; yet it has some disadvantages such as increasing the risk of formation of white spot lesions, because it makes oral hygiene more difficult. It is rational to implement procedures to prevent these lesions. The present study was aimed to assess the effect of CO2 laser and fluoride varnish on the surface of the enamel surface microhardness around the orthodontic braces. Methods: Eighty extracted premolar teeth were selected, scaled, polished with nonfluoridated pumic and metal brackets were bonded to them. Then, they were randomly allocated to 5 groups: control (neither fluoride nor laser is used on enamel surfaces), fluoride (4 minutes fluoride varnish treatment of the enamel surfaces), CO2 laser (10.6 µm CO2 laser irradiation of the teeth), laserfluoride (fluoride application after laser irradiation) and fluoride-laser (fluoride was applied and then teeth were irradiated with laser). After surface treatment around brackets on enamel, the samples were stored in 0.1% thymol for less than 5 days and then they were exposed to a 10-day microbiological caries model. Microhardness values of enamel were evaluated with Vickers test. One sample of each group (5 teeth from 80 samples) was prepared for SEM (scanning electron microscopy) and the data from 75 remaining teeth were analyzed with analysis of variance (ANOVA) and chi-square tests (α =0.05). Results: Microhardness mean values from high to low were as follow: fluoride-laser, laser-fluoride, laser, fluoride and control. Microhardness in fluoride-laser group was significantly higher compared with that of the control group. Distribution adhesive remnant index (ARI) scores were significantly different between groups and most of bond failures occurred at the enamel-adhesive interface in groups 2 to 5 and at the adhesive-bracket interface in the control group. Conclusion: Combination of fluoride varnish and CO2 laser irradiation can reduce enamel demineralization around orthodontic brackets. PMID:29399311

Effect of CO2 Laser and Fluoride Varnish Application on Microhardness of Enamel Surface Around Orthodontic Brackets.

PubMed

Mahmoudzadeh, Majid; Rezaei-Soufi, Loghman; Farhadian, Nasrin; Jamalian, Seyed Farzad; Akbarzadeh, Mahdi; Momeni, Mohammadali; Basamtabar, Masome

2018-01-01

Introduction: Orthodontic treatment has many advantages such as esthetic improvement and self-esteem enhancement; yet it has some disadvantages such as increasing the risk of formation of white spot lesions, because it makes oral hygiene more difficult. It is rational to implement procedures to prevent these lesions. The present study was aimed to assess the effect of CO 2 laser and fluoride varnish on the surface of the enamel surface microhardness around the orthodontic braces. Methods: Eighty extracted premolar teeth were selected, scaled, polished with nonfluoridated pumic and metal brackets were bonded to them. Then, they were randomly allocated to 5 groups: control (neither fluoride nor laser is used on enamel surfaces), fluoride (4 minutes fluoride varnish treatment of the enamel surfaces), CO 2 laser (10.6 µm CO 2 laser irradiation of the teeth), laserfluoride (fluoride application after laser irradiation) and fluoride-laser (fluoride was applied and then teeth were irradiated with laser). After surface treatment around brackets on enamel, the samples were stored in 0.1% thymol for less than 5 days and then they were exposed to a 10-day microbiological caries model. Microhardness values of enamel were evaluated with Vickers test. One sample of each group (5 teeth from 80 samples) was prepared for SEM (scanning electron microscopy) and the data from 75 remaining teeth were analyzed with analysis of variance (ANOVA) and chi-square tests (α =0.05). Results: Microhardness mean values from high to low were as follow: fluoride-laser, laser-fluoride, laser, fluoride and control. Microhardness in fluoride-laser group was significantly higher compared with that of the control group. Distribution adhesive remnant index (ARI) scores were significantly different between groups and most of bond failures occurred at the enamel-adhesive interface in groups 2 to 5 and at the adhesive-bracket interface in the control group. Conclusion: Combination of fluoride varnish and CO2 laser irradiation can reduce enamel demineralization around orthodontic brackets.

Comparison between a CO2 and a Nd-YAG laser with fibertom system in the treatment of frenulum breve

NASA Astrophysics Data System (ADS)

Wozniak, Jakub; Dydowicz, Piotr; Jedrzejczak, Piotr; Opala, Tomasz; Wilczak, Maciej; Pisarska-Krawczyk, Magdalena; Pisarski, Tadeusz

1997-10-01

The study showed the treatment of frenulum breve in 24 patients. Nine of them were treated with CO2 and eight ones with Nd:YAG lasers. In seven males the classical surgical procedures were done. All patients were treated in Department of Reproduction, Institute of Gynecology and Obstetrics, Karol Marcinkowski School of Medical Sciences, Poznan, Poland between March 1995 and September 1996. All procedures were collected successful and no serious complications were observed. The all males are still under control in our department. The use of lasersurgery is the safe and efficient method in treatment of frenulum breve. Lasersurgery may be conducting as the out-patient procedure or one-day surgery because of possibility of NLA and local anesthesia. The use of CO2 seems to be the better method than Nd:YAG laser with fibertom system in treatment of frenulum breve because of shorter time of healing. There are no differences between hemostasis achieved by CO2 and Nd:YAG lasers. The incision effect is the same, when CO2 and Nd:YAG laser with fibertom system are used.

Transmyocardial laser revascularization with a high-power (800 W) CO2 laser: clinical report with 50 cases

NASA Astrophysics Data System (ADS)

Qu, Zheng; Zhang, Zhaoguang; Ye, Jianguang; Yu, Jianbo

1999-09-01

This paper reports the clinical experience in transmyocardial laser revascularization (TMLR) with high power CO2 laser and evaluates the preliminary results of TMLR. TMLR may improve angina pectoris and myocardial perfusion significantly. To switch on the laser in proper order may be helpful to shorten duration of surgery. A gentle removal of fat on the apex may increase the successful transmyocardial penetration.

New refractive method for laser thermal keratoplasty with the Co:MgF2 laser.

PubMed

Horn, G; Spears, K G; Lopez, O; Lewicky, A; Yang, X Y; Riaz, M; Wang, R; Silva, D; Serafin, J

1990-09-01

We have observed corneal curvature changes from laser thermal keratoplasty with a Co:MgF2 laser. We studied corneal curvature changes in rabbits and have identified specific treatment patterns and laser parameters that can correct myopia and astigmatism. These corneal changes, some as large as 8 diopters, have been stable for at least one year, and slitlamp examination demonstrates clear central corneas with normal appearance.

CO2 laser versus cold steel margin analysis following endoscopic excision of glottic cancer

PubMed Central

2014-01-01

Objective To compare the suitability of CO2 laser with steel instruments for margin excision in transoral laser microsurgery. Methods Prospective randomized blinded study. Patients with glottic cancer undergoing laser resection were randomized to margin excision by either steel instruments or CO2 laser. Margins were analyzed for size, interpretability and degree of artifact by a pathologist who was blinded to technique. Results 45 patients were enrolled in the study with 226 total margins taken. 39 margins taken by laser had marked artifact and 0 were uninterpretable. 20 margins taken by steel instruments had marked artifact, and 2 were uninterpretable. Controlling for margin size, the laser technique was associated with increasing degrees of margin artifact (p = 0.210), but there was no difference in crude rates of uninterpretability (p = 0.24). Conclusion Laser margin excision is associated with a greater degree of artifact than steel instrument excision, but was not associated with higher rate of uninterpretability. PMID:24502856

Flexible omnidirectional carbon dioxide laser as an effective tool for resection of brainstem, supratentorial, and intramedullary cavernous malformations.

PubMed

Choudhri, Omar; Karamchandani, Jason; Gooderham, Peter; Steinberg, Gary K

2014-03-01

Lasers have a long history in neurosurgery, yet bulky designs and difficult ergonomics limit their use. With its ease of manipulation and multiple applications, the OmniGuide CO2 laser has reintroduced laser technology to the microsurgical resection of brain and spine lesions. This laser, delivered through a hollow-core fiber lined with a unidirectional mirror, minimizes energy loss and allows precise targeting. To analyze resections performed by the senior author from April 2009 to March 2013 of 58 cavernous malformations (CMs) in the brain and spine with the use of the OmniGuide CO2 laser, to reflect on lessons learned from laser use in eloquent areas, and to share data on comparisons of laser power calibration and histopathology. Data were collected from electronic medical records, radiology reports, operative room records, OmniGuide CO2 laser case logs, and pathology records. Of 58 CMs, approximately 50% were in the brainstem (30) and the rest were in supratentorial (26) and intramedullary spinal locations (2). Fifty-seven, ranging from 5 to 45 mm, were resected, with a subtotal resection in 1. Laser power ranged from 2 to 10 W. Pathology specimens showed minimal thermal damage compared with traditionally resected specimens with bipolar coagulation. The OmniGuide CO2 laser is safe and has excellent precision for the resection of supratentorial, brainstem, and spinal intramedullary CMs. No laser-associated complications occurred, and very low energy was used to dissect malformations from their surrounding hemosiderin-stained parenchymas. The authors recommend its use for deep-seated and critically located CMs, along with traditional tools.

The effects of arterial carbon dioxide partial pressure and sevoflurane on capillary venous cerebral blood flow and oxygen saturation during craniotomy.

PubMed

Klein, Klaus Ulrich; Glaser, Martin; Reisch, Robert; Tresch, Achim; Werner, Christian; Engelhard, Kristin

2009-07-01

Intraoperative routine monitoring of cerebral blood flow and oxygenation remains a technological challenge. Using the physiological principle of carbon dioxide reactivity of cerebral vasculature, we investigated a recently developed neuromonitoring device (oxygen-to-see, O2C device) for simultaneous measurements of regional cerebral blood flow (rvCBF), blood flow velocity (rvVelo), oxygen saturation (srvO2), and hemoglobin amount (rvHb) at the capillary venous level in patients subjected to craniotomy. Twenty-six neurosurgical patients were randomly assigned to anesthesia with 1.4% or 2.0% sevoflurane end-tidal concentration. After craniotomy, a fiberoptic probe was applied on a macroscopically healthy surface of cerebral tissue next to the site of surgery. Simultaneous measurements in 2 and 8 mm cerebral depth were performed in each patient during lower (35 mm Hg) and higher (45 mm Hg) levels (random order) of arterial carbon dioxide partial pressure (PaCO2). The principle of these measurements relies on the combination of laser-Doppler flowmetry (rvCBF, rvVelo) and photo-spectrometry (srvO2, rvHb). Linear models were fitted to test changes of end points (rvCBF, rvVelo, srvO2, rvHb) in response to lower and higher levels of PaCO2, 1.4% and 2.0% sevoflurane end-tidal concentration, and 2 and 8 mm cerebral depth. RvCBF and rvVelo were elevated by PaCO2 independent of sevoflurane concentration in 2 and 8 mm depth of cerebral tissue (P < 0.001). Higher PaCO2 induced an increase in mean srvO2 from 50% to 68% (P < 0.001). RvVelo (P < 0.001) and srvO2 (P = 0.007) were higher in 8 compared with 2 mm cerebral depth. RvHb was not influenced by alterations in PaCO2 but positively correlated to sevoflurane concentration (P = 0.005). Increases in rvCBF and rvVelo by PaCO2 suggest preserved hypercapnic vasodilation under anesthesia with sevoflurane 1.4% and 2.0% end-tidal concentration. A consecutive increase in srvO2 implies that cerebral arteriovenous difference in oxygen was decreased by elevated PaCO2. Unchanged levels of rvHb signify that there was no blood loss during measurements. Data suggest that the device allows detection of local changes in blood flow and oxygen saturation in response to different PaCO2 levels in predominant venous cerebral microvessels.

Standard guidelines of care: CO2 laser for removal of benign skin lesions and resurfacing.

PubMed

Krupashankar, D S

2008-01-01

Resurfacing is a treatment to remove acne and chicken pox scars, and changes in the skin due to ageing. MACHINES: Both ablative and nonablative lasers are available for use. CO 2 laser is the gold standard in ablative lasers. Detailed knowledge of the machines is essential. INDICATIONS FOR CO 2 LASER: Therapeutic indications: Actinic and seborrheic keratosis, warts, moles, skin tags, epidermal and dermal nevi, vitiligo blister and punch grafting, rhinophyma, sebaceous hyperplasia, xanthelasma, syringomas, actinic cheilitis angiofibroma, scar treatment, keloid, skin cancer, neurofibroma and diffuse actinic keratoses. CO 2 laser is not recommended for the removal of tattoos. AESTHETIC INDICATIONS: Resurfacing for acne, chicken pox and surgical scars, periorbital and perioral wrinkles, photo ageing changes, facial resurfacing. PHYSICIANS' QUALIFICATIONS: Any qualified dermatologist (DVD or MD) may practice CO 2 laser. The dermatologist should possess postgraduate qualification in dermatology and should have had specific hands-on training in lasers either during postgraduation or later at a facility which routinely performs laser procedures under a competent dermatologist/plastic surgeon, who has experience and training in using lasers. For the use of CO 2 lasers for benign growths, a full day workshop is adequate. As parameters may vary in different machines, specific training with the available machine at either the manufacturer's facility or at another centre using the machine is recommended. CO 2 lasers can be used in the dermatologist's minor procedure room for the above indications. However, when used for full-face resurfacing, the hospital operation theatre or day care facility with immediate access to emergency medical care is essential. Smoke evacuator is mandatory. Detailed counseling with respect to the treatment, desired effects, possible postoperative complications, should be discussed with the patient. The patient should be provided brochures to study and also given adequate opportunity to seek information. Detailed consent forms need to be completed by the patients. Consent forms should include information on the machine used; possible postoperative course expected and postoperative complications. Preoperative photography should be carried out in all cases of resurfacing. Choice of the machine and the parameters depends on the site, type of lesion, result needed, and the physician's experience. Localized lesions can be treated under eutectic mixture of local anesthesia (EMLA) cream anesthesia or local infiltration anesthesia. Full-face resurfacing can be performed under general anesthesia. Proper postoperative care is important to avoid complications.

Thermoelectronic laser energy conversion for power transmission in space

NASA Technical Reports Server (NTRS)

Britt, E. J.; Yuen, C.

1977-01-01

Long distance transmission of power in space by means of laser beams is an attractive concept because of the very narrow beam divergence. Such a system requires efficient means to both generate the laser beam and to convert the light energy in the beam into useful electric output at the receiver. A plasma-type device known as a Thermo-Electronic Laser Energy Converter (TELEC) has been studied as a method of converting a 10.6 micron CO2 laser beam into electric power. In the TELEC process, electromagnetic radiation is absorbed directly in the plasma electrons producing a high electron temperature. The energetic electrons diffuse out of the plasma striking two electrodes with different areas. Since more electrons are collected by the larger electrode there is a net transport of current, and an EMF is generated in the external circuit. The smaller electrode functions as an electron emitter to provide continuity of the current. Waste heat is rejected from the large electrode. A design for a TELEC system with an input 1 MW laser beam was developed as part of the study. The calculated performance of the system showed an overall efficiency of about 42%.

Catalyst for Carbon Monoxide Oxidation

NASA Technical Reports Server (NTRS)

Davis, Patricia; Brown, Kenneth; VanNorman, John; Brown, David; Upchurch, Billy; Schryer, David; Miller, Irvin

2010-01-01

In many applications, it is highly desirable to operate a CO2 laser in a sealed condition, for in an open system the laser requires a continuous flow of laser gas to remove the dissociation products that occur in the discharge zone of the laser, in order to maintain a stable power output. This adds to the operating cost of the laser, and in airborne or space applications, it also adds to the weight penalty of the laser. In a sealed CO2 laser, a small amount of CO2 gas is decomposed in the electrical discharge zone into corresponding quantities of CO and O2. As the laser continues to operate, the concentration of CO2 decreases, while the concentrations of CO and O2 correspondingly increase. The increasing concentration of O2 reduces laser power, because O2 scavenges electrons in the electrical discharge, thereby causing arcing in the electric discharge and a loss of the energetic electrons required to boost CO2 molecules to lasing energy levels. As a result, laser power decreases rapidly. The primary object of this invention is to provide a catalyst that, by composition of matter alone, contains chemisorbed water within and upon its structure. Such bound moisture renders the catalyst highly active and very long-lived, such that only a small quantity of it needs to be used with a CO2 laser under ambient operating conditions. This object is achieved by a catalyst that consists essentially of about 1 to 40 percent by weight of one or more platinum group metals (Pt, Pd, Rh, Ir, Ru, Os, Pt being preferred); about 1 to 90 percent by weight of one or more oxides of reducible metals having multiple valence states (such as Sn, Ti, Mn, Cu, and Ce, with SnO2 being preferred); and about 1 to 90 percent by weight of a compound that can bind water to its structure (such as silica gel, calcium chloride, magnesium sulfate, hydrated alumina, and magnesium perchlorate, with silica gel being preferred). Especially beneficial results are obtained when platinum is present in the catalyst composition in an amount of about 5 to 25 (especially 7) percent by weight, SnO2 is present in an amount of about 30 to 40 (especially 40) percent by weight, and silica gel is present in an amount of 45 to 55 (especially 50) percent by weight. The composition of this catalyst was suggested by preliminary experiments in which a Pt/SnO2 catalyst was needed for bound water to enhance its activity. These experimental results suggested that if the water were bound to the surface, this water would enhance and prolong catalyst activity for long time periods. Because the catalyst is to be exposed to a laser gas mixture, and because a CO2 laser can tolerate only a very small amount of moisture, a hygroscopic support for the catalyst would provide the needed H2O into the gas. Silica gel is considered to be superior because of its property to chemisorb water on its surface over a wide range of moisture content.

Analysis of Pulsed Airborne Lidar Measurements of Atmospheric CO2 Column Absorption from 3-13 km Altitudes

NASA Technical Reports Server (NTRS)

Abshire, James B.; Weaver, Clark J.; Riris, Haris; Mao, Jianping; Sun, Xiaoli; Allan, Graham R.; Hasselbrack, William; Browell, Edward V.

2011-01-01

We have developed a pulsed lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's ASCENDS space mission [1]. It uses two pulsed laser transmitters allowing simultaneous measurement of a CO2 absorption line in the 1575 nm band, O2 extinction in the Oxygen A-band, surface height and backscatter profile. The lasers are precisely stepped in wavelength across the CO2 line and an O2 line region during the measurement. The direct detection receiver measures the energies of the laser echoes from the surface along with the range profile of scattering in the path. The column densities for the CO2 and O2 gases are estimated from the ratio of the on- and off-line signals via the integrated path differential absorption (IPDA) technique. The time of flight of the laser pulses is used to estimate the height of the scattering surface and to reject laser photons scattered in the atmosphere. We developed an airborne lidar to demonstrate an early version of the CO2 measurement from the NASA Glenn Lear-25 aircraft. The airborne lidar stepped the pulsed laser's wavelength across the selected CO2 line with 20 wavelength steps per scan. The line scan rate is 450 Hz, the laser pulse widths are 1 usec, and laser pulse energy is 24 uJ. The time resolved laser backscatter is collected by a 20 cm telescope, detected by a NIR photomultiplier and is recorded on every other reading by a photon counting system [2]. During August 2009 we made a series of 2.5 hour long flights and measured the atmospheric CO2 absorption and line shapes using the 1572.33 nm CO2 line. Measurements were made at stepped altitudes from 3-13 km over locations in the US, including the SGP ARM site in Oklahoma, central Illinois, north-eastern North Carolina, and over the Chesapeake Bay and the eastern shore of Virginia. Although the received signal energies were weaker than expected for ASCENDS, clear CO2 line shapes were observed at all altitudes, and some measurements were made through thin clouds. The Oklahoma and east coast flights were coordinated with a LaRC/ITT CO2 lidar on the LaRC UC-12 aircraft, and in-situ measurements were made using its CO2 sensor and radiosondes. We have conducted an analysis of the ranging and IPDA lidar measurements from these four flights. Most flights had 5-6 altitude steps with 200-300 seconds of recorded measurements per step. We used a cross-correlation approach to process the laser echo records. This was used to estimate the range to the scattering surface, to define the edges of the laser pulses and to determine echo pulse energy at each wavelength. We used a minimum mean square approach to fit an instrument response function and to solve for the best-fit CO2 absorption line shape. We then calculated the differential optical depth (DOD) of the fitted CO2 line. We computed its statistics at the various altitude steps, and compare them to the DODs calculated from spectroscopy based on HITRAN 2008 and the column conditions calculated from the airborne in-situ readings. The results show the lidar and in-situ measurements have very similar DOD change with altitude and greater than 10 segments per flight where the scatter in the lidar measurements are less than or equal to 1ppm. We also present the results from subsequent CO2 column absorption measurements, which were made with stronger detected signals during three flights on the NASA DC-8 over the southwestern US in during July 2010.

Solar pumped continuous wave carbon dioxide laser

NASA Technical Reports Server (NTRS)

Yesil, O.; Christiansen, W. H.

1978-01-01

In an effort to demonstrate the feasibility of a solar pumped laser concept, gain has been measured in a CO2-He laser medium optically pumped by blackbody radiation. Various gas mixtures of CO2 and He have been pumped by blackbody radiation emitted from an electrically heated oven. Using a CO2 laser as a probe, an optical gain coefficient of 1.8 x 10 to the -3rd/cm has been measured at 10.6 microns for a 9:1 CO2-He mixture at an oven temperature of about 1500 K, a gas temperature of about 400 K and a pressure of about 1 torr. This corresponds to a small signal gain coefficient when allowance is made for saturation effects due to the probe beam, in reasonable agreement with a theoretical value.

Enhanced light emission near 2.7 μm from Er-Nd co-doped germanate glass

NASA Astrophysics Data System (ADS)

Bai, Gongxun; Tao, Lili; Li, Kefeng; Hu, Lili; Tsang, Yuen Hong

2013-04-01

Laser glass gain medium that can convert low cost 808 nm diode laser into 2.7 μm has attracted considerable interest due to its potential application for medical surgery fiber laser system. In this study, enhanced 2.7 μm emission has been achieved in Er3+:germanate glass by co-doping with Nd3+ ions under the excitation of an 808 nm diode laser. In the co-doped sample, the experimental results show that the harmful visible emissions via up-conversion were effectively restricted. The reduction of 1.5 μm emission was also detected in the co-doped sample, which indicates significant de-excitation of 4I13/2 Er3+ ion through energy transfer and non-radiative decay in Nd3+ ions. In conclusion, the 2.7 μm emission enhancement achieved was due to the increased optical absorption of 808 nm, efficient energy transfer (ET) with efficiency of 81.73% between Er3+ and Nd3+ ions, and shortening the lifetime of the lower lasing level 4I13/2 Er3+ in the co-doped sample. Therefore, Er3+/Nd3+ co-doped germanate glass could be used to fabricate fiber optical gain media for 2.7 μm laser generation.

Cutaneous pain effects induced by Nd:YAG and CO2 laser stimuli

NASA Astrophysics Data System (ADS)

Wang, Jia-Rui; Yu, Guang-Yuan; Yang, Zai-Fu; Chen, Hong-Xia; Hu, Dong-Dong; Zou, Xian-Biao

2012-12-01

The near infrared laser technique can activate cutaneous nociceptors with high specificity and reproducibility and be used in anti-riot equipment. This study aimed to explore cutaneous pain effect and determine the threshold induced by Nd:YAG and CO2 laser stimuli. The corresponding wavelength was 1.32μm and 10.6μm. The pain effect was assessed in three healthy subjects (1 woman and 2 men) on the skin of dorsum of both hands. The energy of each pulse and whether the subjects felt a painful sensation after each stimulus were recorded. A simplified Bliss Method was used to calculate the pain threshold which were determined under three pulse durations for Nd:YAG laser and one pulse duration for CO2 laser. As a result the pain thresholds were determined to be 5.6J/cm2, 5.4J/cm2 and 5.0J/cm2 respectively when using Nd:YAG laser, 4.0mm beam diameter, 8ms, 0.1s and 1s pulse duration. The pain threshold was 1.0J/cm2 when using CO2 laser, 4.0mm beam diameter and 0.1s pulse duration. We concluded that the threshold of cutaneous pain elicited by 1.32μm laser was independent upon the pulse duration when the exposure time ranged from 8ms to 1s. Under the same exposure condition, the threshold of cutaneous pain elicited by 1.32μm laser was higher than that elicited by 10.6μm laser.

The effect of CO2 and Nd:YAP lasers on CAD/CAM Ceramics: SEM, EDS and thermal studies.

PubMed

El Gamal, Ahmed; Fornaini, Carlo; Rocca, Jean Paul; Muhammad, Omid H; Medioni, Etienne; Cucinotta, Annamaria; Brulat-Bouchard, Nathalie

2016-03-31

The objective of this study was to investigate the interaction of infrared laser light on Computer Aided Design and Computer Aided Manufacturing (CAD/CAM) ceramic surfaces. Sixty CAD/CAM ceramic discs were prepared and divided into two different groups: lithiumdisilicate ceramic (IPSe.maxCADs) and Zirconia ceramic (IPSe.maxZirCADs). The laser irradiation was performed on graphite and non-graphite surfaces with a Carbon Dioxide laser at 5W and 10W power in continuous mode (CW mode) and with Neodymium Yttrium Aluminum Perovskite (Nd:YAP) laser at 10W. Surface textures and compositions were examined using Scanning Electron Microscopy (SEM), and Energy Dispersive Spectroscopy (EDS). Thermal elevation was measured by thermocouple during laser irradiation. The SEM observation showed a rough surface plus cracks and fissures on CO2 10W samples and melting areas in Nd:YAP samples; moreover, with CO2 5W smooth and shallow surfaces were observed. EDS analysis revealed that laser irradiation does not result in modifications of the chemical composition even if minor changes in the atomic mass percentage of the components were registered. Thermocouple showed several thermal changes during laser irradiation. CO2 and Nd:YAP lasers modify CAD/CAM ceramic surface without chemical composition modifications.

A compact, rugged, high repetition rate CO2 laser incorporating catalyst

NASA Technical Reports Server (NTRS)

Schwarzenberger, P. M.; Matzangou, X.

1990-01-01

The principal design features and operating characteristics of a high repetition rate CO2 laser are outlined. The laser is a compact, rugged unit, completely sealed and incorporating an unheated solid catalyst. Stable operation has been successfully demonstrated over a temperature range of -35 C to 65 C.

A blackbody radiation-pumped CO2 laser experiment

NASA Technical Reports Server (NTRS)

Christiansen, W. H.; Insuik, R. J.; Deyoung, R. J.

1982-01-01

Thermal radiation from a high temperature oven was used as an optical pump to achieve lasing from CO2 mixtures. Laser output as a function of blackbody temperature and gas conditions is described. This achievement represents the first blackbody cavity pumped laser and has potential for solar pumping.

Room-temperature operation of a Co:MgF2 laser

NASA Technical Reports Server (NTRS)

Welford, D.; Moulton, P. F.

1988-01-01

A normal-mode, pulsed Co:MgF2 laser has been operated at room temperature for the first time. Continuous tuning from 1750 to 2500 nm with pulse energies up to 70 mJ and 46-percent slope efficiency was obtained with a 1338-nm Nd:YAG pump laser.

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.

The use of laser CO2 in salivary gland diseases

NASA Astrophysics Data System (ADS)

Ciolfi, C.; Rocchetti, F.; Fioravanti, M.; Tenore, G.; Palaia, G.; Romeo, U.

2016-03-01

Salivary gland diseases can include reactive lesions, obstructive lesions, and benign tumors. All these clinical entities are slow growing. Salivary glands reactive lesions, such as mucoceles, can result from extravasation of saliva into the surrounding soft tissue or from retention of saliva within the duct. Sialolithiasis, one of the most common obstructive lesions, is generally due to calculi, which are attributed to retention of saliva. Monomorphic adenoma is a salivary gland benign tumor, which is exclusively resulted from proliferation of epithelial cells, with no alterations interesting the connective tissue. The elective therapy of these lesions is surgical excision because sometimes they can be accompained by difficulties during chewing and phonation and can interfere with prosthesis's stability. The aim of the study is to evaluate the efficacy of CO2 laser in the treatment of patients with salivary gland diseases. Three different cases - a mucocele, a scialolithiasis and a monomorphic adenoma - were treated with CO2 laser excision (CW and 4W), under local anesthesia. Two different techniques were used: circumferential incision for the adenoma, and mucosa preservation technique for mucocele and sialolithiasis. In each case final haemostasis was obtained by thermocoagulation, but suture was applied to guarantee good healing by sewing up the flaps. The patients were checked after twenty days and the healing was good. The carbon dioxide laser (CO2 laser) was one of the earliest gas laser to be developed, and is still the highest-power continuous wave laser that is currently available. In dentistry the CO2 laser produces a beam of infrared light with the principal wavelength bands centering around 9.4 and 10.6 micrometers. Laser excision can be very useful in oral surgery. In the cases presented CO2 laser offered, differently from traditional surgery, simplified surgical technique, shorter duration of operation, minimal postoperative pain, minimal scarring, bloodless field and the possibility to realize minimally invasive surgery. These advantages made the operation tolerable for the patients, that became more compliant. Optimum functional results can be expected.

Sealed-off CO2 laser with In-Au alloy sealing

NASA Astrophysics Data System (ADS)

Iehisa, N.; Fukaya, K.; Karube, N.

1986-02-01

The In-Au alloy sealing was found to satisfy all the requirements imposed on the sealed-off CO2 lasers. The sealing between different materials such as quartz, SUS 303, Si, and ZnSe was shown to withstand the thermal shock test, and gave the He leak rate lower than 1×10-9 atm cc/s both before and after the tests. It was also proved that the transmittance characteristics of dielectric coated output couplers did not change after the sealing. The sealed-off CO2 lasers with La1-xSrxCoO3 perovskite oxide cathodes sealed with this technique produced the operational life of 3000 h at the laser power level of 50 W/m.

Experimental Investigation of Airbreathing Laser Propulsion Engines: CO2TEA vs. EDL

NASA Astrophysics Data System (ADS)

Mori, Koichi; Sasoh, Akihiro; Myrabo, Leik N.

2005-04-01

Single pulse laboratory experiments were carried out with a high-power CO2 Transversely-Exited Atmospheric (TEA) laser using parabolic laser propulsion (LP) engines of historic interest: 1) an original Pirri/ AERL bell engine, and 2) a scaled-up 11-cm diameter version with identical geometry. The objective was to quantify the effects of pulse duration upon the impulse coupling coefficient performance — with pulse energy as the parametric variable. Performance data from the TEA laser are contrasted with former results derived from AVCO Everett Research Laboratory and PLVTS CO2 electron discharge lasers (EDL). The `short-pulse' 2-microsecond TEA laser tests generated results that were distinctively different from that of the `long-pulse' EDL sources. The TC-300 TEA laser employed an unstable resonator to deliver up to 380 joules, and the square output beam measured 15-cm on a side, with a hollow 8-cm center. A standard ballistic pendulum was employed to measure the performance.

77 FR 27081 - II-VI, Incorporated, Infrared Optics-Saxonburg Division, Saxonburg, Pennsylvania; Notice of...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-08

...). The workers were engaged in employment related to the production of infrared and CO 2 laser optics... 2 laser optics, and related materials, from 2009 to 2010 or from January- October 2010 compared to... that the workers' firm did not shift production of infrared and CO 2 laser optics, and related...

77 FR 21586 - II-VI, Incorporated, Infrared Optics-Saxonburg Division, Saxonburg, PA; Notice of Affirmative...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-10

...). The workers were engaged in employment related to the production of infrared and CO 2 laser optics... 2 laser optics, and related materials, from 2009 to 2010 or from January- October 2010 compared to... investigation revealed that the workers' firm did not shift production of infrared and CO 2 laser optics, and...

A Simple Device for Lens-to-Sample Distance Adjustment in Laser-Induced Breakdown Spectroscopy (LIBS).

PubMed

Cortez, Juliana; Farias Filho, Benedito B; Fontes, Laiane M; Pasquini, Celio; Raimundo, Ivo M; Pimentel, Maria Fernanda; de Souza Lins Borba, Flávia

2017-04-01

A simple device based on two commercial laser pointers is described to assist in the analysis of samples that present uneven surfaces and/or irregular shapes using laser-induced breakdown spectroscopy (LIBS). The device allows for easy positioning of the sample surface at a reproducible distance from the focusing lens that conveys the laser pulse to generate the micro-plasma in a LIBS system, with reproducibility better than ±0.2 mm. In this way, fluctuations in the fluence (J cm -2 ) are minimized and the LIBS analytical signals can be obtained with a better precision even when samples with irregular surfaces are probed.

Intensity-Modulated Continuous-Wave Laser Absorption Spectrometer at 1.57 Micrometer for Atmospheric CO2 Measurements

NASA Technical Reports Server (NTRS)

Lin, Bing

2014-01-01

Understanding the earth's carbon cycle is essential for diagnosing current and predicting future climates, which requires precise global measurements of atmospheric CO2 through space missions. The Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) space mission will provide accurate global atmospheric CO2 measurements to meet carbon science requirements. The joint team of NASA Langley Research Center and ITT Exelis, Inc. proposes to use the intensity-modulated, continuous-wave (IM-CW) laser absorption spectrometer (LAS) approach for the ASCENDS mission. Prototype LAS instruments have been developed and used to demonstrate the power, signal-to-noise ratio, precision and accuracy, spectral purity, and stability of the measurement and the instrument needed for atmospheric CO2 observations from space. The ranging capability from laser platform to ground surfaces or intermediate backscatter layers is achieved by transmitted range-encoded IM laser signals. Based on the prototype instruments and current lidar technologies, space LAS systems and their CO2 column measurements are analyzed. These studies exhibit a great potential of using IM-CW LAS system for the active space CO2 mission ASCENDS.

Imaging Fourier transform spectroscopy of the boundary layer plume from laser irradiated polymers and carbon materials

NASA Astrophysics Data System (ADS)

Acosta, Roberto I.

The high-energy laser (HEL) lethality community needs for enhanced laser weapons systems requires a better understanding of a wide variety of emerging threats. In order to reduce the dimensionality of laser-materials interaction it is necessary to develop novel predictive capabilities of these events. The objective is to better understand the fundamentals of laser lethality testing by developing empirical models from hyperspectral imagery, enabling a robust library of experiments for vulnerability assessments. Emissive plumes from laser irradiated fiberglass reinforced polymers (FRP), poly(methyl methacrylate) (PMMA) and porous graphite targets were investigated primarily using a mid-wave infrared (MWIR) imaging Fourier transform spectrometer (FTS). Polymer and graphite targets were irradiated with a continuous wave (cw) fiber lasers. Data was acquired with a spectral resolution of 2 cm-1 and spatial resolution as high as 0.52 mm2 per pixel. Strong emission from H2O, CO, CO2 and hydrocarbons were observed in the MWIR between 1900-4000 cm-1. A single-layer radiative transfer model was developed to estimate spatial maps of temperature and column densities of CO and CO2 from the hyperspectral imagery of the boundary layer plume. The spectral model was used to compute the absorption cross sections of CO and CO2, using spectral line parameters from the high temperature extension of the HITRAN. Also, spatial maps of gas-phase temperature and methyl methacrylate (MMA) concentration were developed from laser irradiated carbon black-pigmented PMMA at irradiances of 4-22 W/cm2. Global kinetics interplay between heterogeneous and homogeneous combustion kinetics are shown from experimental observations at high spatial resolutions. Overall the boundary layer profile at steady-state is consistent with CO being mainly produced at the surface by heterogeneous reactions followed by a rapid homogeneous combustion in the boundary layer towards buoyancy.

Visible light plasmonic heating of Au-ZnO for the catalytic reduction of CO 2

DOE PAGES

Wang, Congjun; Ranasingha, Oshadha; Natesakhawat, Sittichai; ...

2013-01-01

Plasmonic excitation of Au nanoparticles attached to the surface of ZnO catalysts using low power 532 nm laser illumination leads to significant heating of the catalyst and the conversion of CO 2 and H 2 reactants to CH 4 and CO products. Temperature-calibrated Raman spectra of ZnO phonons show that intensity-dependent plasmonic excitation can controllably heat Au–ZnO from 30 to ~600 °C and simultaneously tune the CH 4 : CO product ratio. The laser induced heating and resulting CH 4 : CO product distribution agrees well with predictions from thermodynamic models and temperature-programmed reaction experiments indicating that the reaction ismore » a thermally driven process resulting from the plasmonic heating of the Au-ZnO. The apparent quantum yield for CO 2 conversion under continuous wave (cw) 532 nm laser illumination is 0.030%. The Au-ZnO catalysts are robust and remain active after repeated laser exposure and cycling. The light intensity required to initiate CO 2 reduction is low ( ~2.5 x 10 5 W m -2) and achievable with solar concentrators. Our results illustrate the viability of plasmonic heating approaches for CO 2 utilization and other practical thermal catalytic applications.« less

Catalytic recombination of dissociation products with Pt/SnO2 for rare and common isotope long-life, closed-cycle CO2 lasers

NASA Technical Reports Server (NTRS)

Brown, Kenneth G.; Sidney, B. D.; Schryer, D. R.; Upchurch, B. T.; Miller, I. M.

1986-01-01

This paper reports results on recombination of pulsed CO2 laser dissociation products with Pt/SnO2 catalysts, and supporting studies in a surrogate laboratory catalyst reactor. The closed-cycle, pulsed CO2 laser has been continuously operated for one million pulses with an overall power degradation of less than 5 percent by flowing the laser gas mixture through a 2-percent Pt/SnO2 catalyst bed. In the surrogate laboratory reactor, experiments have been conducted to determine isotopic exchange with the catalyst when using rare-isotope gases. The effects of catalyst pretreatment, sample weight, composition, and temperature on catalyst efficiency have also been determined.

Modematic: a fast laser beam analyzing system for high power CO2-laser beams

NASA Astrophysics Data System (ADS)

Olsen, Flemming O.; Ulrich, Dan

2003-03-01

The performance of an industrial laser is very much depending upon the characteristics of the laser beam. The ISO standards 11146 and 11154 describing test methods for laser beam parameters have been approved. To implement these methods in industry is difficult and especially for the infrared laser sources, such as the CO2-laser, the availabl analyzing systems are slow, difficult to apply and having limited reliability due to the nature of the detection methods. In an EUREKA-project the goal was defined to develop a laser beam analyzing system dedicated to high power CO2-lasers, which could fulfill the demands for an entire analyzing system, automating the time consuming pre-alignment and beam conditioning work required before a beam mode analyses, automating the analyzing sequences and data analysis required to determine the laser beam caustics and last but not least to deliver reliable close to real time data to the operator. The results of this project work will be described in this paper. The research project has led to the development of the Modematic laser beam analyzer, which is ready for the market.

Catalysts for long-life closed-cycle CO2 lasers

NASA Technical Reports Server (NTRS)

Schryer, David R.; Sidney, Barry D.; Miller, Irvin M.; Hess, Robert V.; Wood, George M.; Batten, Carmen E.; Burney, Lewis G.; Hoyt, Ronald F.; Paulin, Patricia A.; Brown, Kenneth G.

1987-01-01

Long-life, closed-cycle operation of pulsed CO2 lasers requires catalytic CO-O2 recombination both to remove O2, which is formed by discharge-induced CO2 decomposition, and to regenerate CO2. Platinum metal on a tin (IV) oxide substrate (Pt/SnO2) has been found to be an effective catalyst for such recombination in the desired temperature range of 25 to 100 C. This paper presents a description of ongoing research at NASA-LaRC on Pt/SnO2 catalyzed CO-O2 recombination. Included are studies with rare-isotope gases since rare-isotope CO2 is desirable as a laser gas for enhanced atmospheric transmission. Results presented include: (1) achievement of 98% to 100% conversion of a stoichiometric mixture of CO and O2 to CO2 for 318 hours (greater than 1 x 10 to the 6th power seconds), continuous, at a catalyst temperature of 60 C, and (2) development of a technique verified in a 30-hour test, to prevent isotopic scrambling when CO-18 and O-18(2) are reacted in the presence of a common-isotope Pt/Sn O-16(2) catalyst.

367 cases of CO2 laser therapy on facial acne

NASA Astrophysics Data System (ADS)

Gao, Yunqing; Liu, Songhao; Zhang, You; Liu, T. C.

1996-09-01

Since 1989, we have cured 367 persons of facial acne of different course by using direct irradiation of high-power CO2 laser combing with operative therapy of low-power CO2 laser. The cure rate is 100 percent. In this paper, we stated the therapeutic approach. It was shown that this therapeutic approach is simple and effective, and its recurrence rate is zero. There are no cicatrices after healing. It is easy to accept it, and is worthy of extension.

Experimental and clinical standards, and evolution of lasers in neurosurgery.

PubMed

Devaux, B C; Roux, F X

1996-01-01

From initial experiments of ruby, argon and CO2 lasers on the nervous system so far, dramatic progress was made in delivery systems technology as well as in knowledge of laser-tissue interaction effects and hazards through various animal experiments and clinical experience. Most surgical effects of laser light on neural tissue and the central nervous system (CNS) are thermal lesions. Haemostasis, cutting and vaporization depend on laser emission parameters--wavelength, fluence and mode--and on the exposed tissues optical and thermal properties--water and haemoglobin content, thermal conductivity and specific heat. CO2 and Nd-YAG lasers have today a large place in the neurosurgical armamentarium, while new laser sources such as high power diode lasers will have one in the near future. Current applications of these lasers derive from their respective characteristics, and include CNS tumour and vascular malformation surgery, and stereotactic neurosurgery. Intracranial, spinal cord and intra-orbital meningiomas are the best lesions for laser use for haemostasis, dissection and tissue vaporization. Resection of acoustic neuromas, pituitary tumours, spinal cord neuromas, intracerebral gliomas and metastases may also benefit from lasers as accurate, haemostatic, non-contact instruments which reduce surgical trauma to the brain and eloquent structures such as brain stem and cranial nerves. Coagulative lasers (1.06 microns and 1.32 microns Nd-YAG, argon, or diode laser) will find an application for arteriovenous malformations and cavernomas. Any fiberoptic-guided laser will find a use during stereotactic neurosurgical procedures, including image-guided resection of tumours and vascular malformations and endoscopic tumour resection and cysts or entry into a ventricle. Besides these routine applications of lasers, laser interstitial thermotherapy (LITT) and photodynamic therapy (PDT) of brain tumours are still in the experimental stage. The choice of a laser in a neurosurgical operating room implies an evaluation of the laser use (applications, frequency), of the available budget and costs--including purchase, maintenance and staff training--, and material that will be necessary: unit, peripherals, safety devices and measures, training programme. Future applications of lasers in neurosurgery will come from technological advances and refined experimental applications. The availability of new wavelength, tunable, small sized and "smart" laser units, will enlarge the thermal and non-thermal interactions between laser energy and neural tissue leading to new surgical applications. Tissue photo-ablation, photohynamic therapy using second generation of photosensitizers, updated thermotherapy protocols, are current trends for further use of lasers in neurosurgery.

Effect of surface-breakdown plasma on metal drilling by pulsed CO2-laser radiation

NASA Astrophysics Data System (ADS)

Arutiunian, P. V.; Baranov, V. Iu.; Bobkov, I. V.; Bol'Shakov, L. A.; Dolgov, V. A.

1988-03-01

The effect of low-threshold surface breakdown produced by short (5-microsec) CO2-laser pulses on the metal drilling process is investigated. Data on the interaction of metals with laser pulses having the same duration but different shape are shown to be different. The effect of the ambient atmospheric pressure on the laser drilling process is investigated.

Pulsed CO2 characterization for lidar use

NASA Technical Reports Server (NTRS)

Jaenisch, Holger M.

1992-01-01

An account is given of a scaled functional testbed laser for space-qualified coherent-detection lidar applications which employs a CO2 laser. This laser has undergone modification and characterization for inherent performance capabilities as a model of coherent detection. While characterization results show good overall performance that is in agreement with theoretical predictions, frequency-stability and pulse-length limitations severely limit the laser's use in coherent detection.

CO2 Laser Excision of a Pyogenic Granuloma Associated with Dental Implants: A Case Report and Review of the Literature.

PubMed

Truschnegg, Astrid; Acham, Stephan; Kqiku, Lumnije; Beham, Alfred; Jakse, Norbert

2016-09-01

This article reports the CO2 laser excision of a pyogenic granuloma related to dental implants and reviews the current literature on this pathology in association with dental implants. Five publications describe pyogenic granulomas related to dental implants, and a further one describes the removal of such a lesion with an Er:YAG laser; removal with a CO2 laser is not reported. A 67-year-old male patient presented with a hyperplastic gingival lesion around two implants in the left lower jaw. The hyperplastic tissue was removed with a CO2 laser (Lasram; model OPAL 25, 25 W continuous wave, 10.600 nm, gas laser), and a vestibuloplasty was performed. The excised tissue was examined histopathologically. The patient was followed up after 4 weeks, 6 weeks, 6 months, and 1 year, and a panoramic X-ray was also made. There were no complications during surgery or follow-up. The panoramic X-ray taken 1 year after excision showed neither vertical bone loss nor impaired osseointegration of the implant. Histopathology reported a pyogenic granuloma. After vestibuloplasty, the height of the fixed mucosa was satisfactory. The CO2 laser seems to be a safe and appropriate tool for removal of a pyogenic granuloma in close proximity to dental implants. The laser parameters must, however, be chosen carefully and any additional irritants should be excluded to prevent a recurrence.

CO2-Doped Diamond: A Potential Solid-State CO2 Laser Material?

NASA Technical Reports Server (NTRS)

Tratt, D.

1994-01-01

This paper describes a novel concept for a solid-state CO subscript 2 laser medium which, by eschewing the gas-phase approach, may offer prospects for a compact, robust 9 - 11 (micro)m coherent source, coupled with the potentially superior frequency stability characteristics afforded by monolithic solid-state construction.

Cutaneous resurfacing with CO2 and erbium: YAG lasers: preoperative, intraoperative, and postoperative considerations.

PubMed

Alster, T S

1999-02-01

The development and integration of pulsed and scanned CO2 and erbium:YAG laser systems into mainstream surgical practice over the past years has revolutionized cutaneous resurfacing. These lasers are capable of delivering to skin high peak fluences to effect controlled tissue vaporization, while leaving an acceptably narrow zone of residual thermal damage. The inherent technological differences that exist between the two distant laser systems in terms of ablation depths, degree of thermal coagulation, and postoperative side-effects and complications guide patient selection and management. This article reviews the basic principles of CO2 and erbium:YAG laser resurfacing, including preoperative, intraoperative, and postoperative patient considerations. Side-effects and complications encountered after laser resurfacing are discussed with specific guidelines provided on their appropriate management. Anticipated future developments and cutting-edge research endeavors in cutaneous laser resurfacing are also briefly outlined.

Laser Welding and Syncristallization Techniques Comparison: In Vitro Study

PubMed Central

Fornaini, C.; Merigo, E.; Vescovi, P.; Meleti, M.; Nammour, S.

2012-01-01

Background. Laser welding was first reported in 1967 and for many years it has been used in dental laboratories with several advantages versus the conventional technique. Authors described, in previous works, the possibility of using also chair-side Nd : YAG laser device (Fotona Fidelis III, λ = 1064 nm) for welding metallic parts of prosthetic appliances directly in the dental office, extra- and also intra-orally. Syncristallisation is a soldering technique based on the creation of an electric arc between two electrodes and used to connect implants to bars intra-orally. Aim. The aim of this study was to compare two different laser welding devices with a soldering machine, all of these used in prosthetic dentistry. Material and Methods. In-lab Nd : YAG laser welding (group A = 12 samples), chair-side Nd : YAG laser welding (group B = 12 samples), and electrowelder (group C = 12 samples) were used. The tests were performed on 36 CrCoMo plates and the analysis consisted in evaluation, by microscopic observation, of the number of fissures in welded areas of groups A and B and in measurement of the welding strength in all the groups. The results were statistically analysed by means of one-way ANOVA and Tukey-Kramer multiple comparison tests. Results. The means and standard deviations for the number of fissures in welded areas were 8.12 ± 2.59 for group A and 5.20 ± 1.38 for group B. The difference was statistical significant (P = 0.0023 at the level 95%). On the other hand, the means and standard deviations for the traction tests were 1185.50 ± 288.56 N for group A, 896.41 ± 120.84 N for group B, and 283.58 ± 84.98 N for group C. The difference was statistical significant (P = 0.01 at the level 95%). Conclusion. The joint obtained by welding devices had a significant higher strength compared with that obtained by the electrowelder, and the comparison between the two laser devices used demonstrated that the chair-side Nd : YAG, even giving a lower strength to the joints, produced the lowest number of fissures in the welded area. PMID:22778737

Experimental comparative study on morphological effects of different lasers on the liver.

PubMed

Godlewski, G; Miro, L; Chevalier, J M; Bureau, J P

1982-01-01

Three types of laser radiation were compared as to their capabilities in hepatic surgery using 17 New Zealand rabbits. In four animals, subtotal scalpel lobectomy was performed, the hepatic pedicle being clamped. Hemostasis is obtained by means of argon or Nd YAG laser as long as the internal diameter of the vessels encountered is less than 4.5 mm. Nd YAG laser requires a power output four times higher than argon laser to obtain hemostasis. In six animals limited resection was performed by means of Nd YAG and CO2 lasers. CO2 radiation supplied insufficient hemostasis whenever the vessel diameter was more than 1 mm despite an excellent cutting power. Nd YAG radiation created an important necrosis zone due to thermal diffusion. In seven animals various focal hepatic lesions produced by the three types of laser were compared. Argon laser induced superficial and regularly round lesion, Nd YAG laser deeper, cauliflower-like lesions with thermal diffusion following especially vessels. Veins presented thrombosis of their blood content and coagulation necrosis of their wall. The amount of glycogenic granulation decreased. The CO2 laser induced very sharp punctual lesion without necrosis. Electron-microscopic sections revealed faint shadowy liver cells closet to the thermal source and bubbled mitochondria containing disrupted critea around the lesion. In later lesions Nd YAG laser produced more extensive fibrosis than argon or CO2 laser. After first clinical trials we believe that laser irradiation is actually an adjuvant safety factor in current hepatic surgery, whereas the Nd YAG laser could be of real interest in metastatic carcinoma destruction in liver.

Spectrally Tailored Pulsed Thulium Fiber Laser System for Broadband Lidar CO2 Sensing

NASA Technical Reports Server (NTRS)

Heaps, William S.; Georgieva, Elena M.; McComb, Timothy S.; Cheung, Eric C.; Hassell, Frank R.; Baldauf, Brian K.

2011-01-01

Thulium doped pulsed fiber lasers are capable of meeting the spectral, temporal, efficiency, size and weight demands of defense and civil applications for pulsed lasers in the eye-safe spectral regime due to inherent mechanical stability, compact "all-fiber" master oscillator power amplifier (MOPA) architectures, high beam quality and efficiency. Thulium fiber's longer operating wavelength allows use of larger fiber cores without compromising beam quality, increasing potential single aperture pulse energies. Applications of these lasers include eye-safe laser ranging, frequency conversion to longer or shorter wavelengths for IR countermeasures and sensing applications with otherwise tough to achieve wavelengths and detection of atmospheric species including CO2 and water vapor. Performance of a portable thulium fiber laser system developed for CO2 sensing via a broadband lidar technique with an etalon based sensor will be discussed. The fielded laser operates with approximately 280 J pulse energy in 90-150ns pulses over a tunable 110nm spectral range and has a uniquely tailored broadband spectral output allowing the sensing of multiple CO2 lines simultaneously, simplifying future potentially space based CO2 sensing instruments by reducing the number and complexity of lasers required to carry out high precision sensing missions. Power scaling and future "all fiber" system configurations for a number of ranging, sensing, countermeasures and other yet to be defined applications by use of flexible spectral and temporal performance master oscillators will be discussed. The compact, low mass, robust, efficient and readily power scalable nature of "all-fiber" thulium lasers makes them ideal candidates for use in future space based sensing applications.

First field determination of the 13C/12C isotope ratio in volcanic CO2 by diode-laser.

PubMed

Castrillo, A; Casa, G; van Burgel, M; Tedesco, D; Gianfrani, L

2004-12-27

Carbon isotope ratio analysis using a laser-based technique has been performed in the field, on the gaseous emissions from an active volcano. We here describe that 13CO2/12CO2 determinations can be carried out in a quasi-continuous regime using a compact, selective and sensitive diode laser spectrometer at a wavelength of 2 mum. Within the Solfatara crater (near Naples, Italy), in a very harsh environment, we were able to determine relative 13CO2/12CO2 values, on the highest flux fumarole, with an accuracy of 0.5 per thousand. Regular and frequent observations of the carbon isotopes in volcanic gases, which become possible with our methodology, are of the utmost importance for geochemical surveillance of volcanoes.

Scaling studies of solar pumped lasers

NASA Astrophysics Data System (ADS)

Christiansen, W. H.; Chang, J.

1985-08-01

A progress report of scaling studies of solar pumped lasers is presented. Conversion of blackbody radiation into laser light has been demonstrated in this study. Parametric studies of the variation of laser mixture composition and laser gas temperature were carried out for CO2 and N2O gases. Theoretical analysis and modeling of the system have been performed. Reasonable agreement between predictions in the parameter variation and the experimental results have been obtained. Almost 200 mW of laser output at 10.6 micron was achieved by placing a small sapphire laser tube inside an oven at 1500 K the tube was filled with CO2 laser gas mixture and cooled by longitudinal nitrogen gas flow.

Scaling studies of solar pumped lasers

NASA Technical Reports Server (NTRS)

Christiansen, W. H.; Chang, J.

1985-01-01

A progress report of scaling studies of solar pumped lasers is presented. Conversion of blackbody radiation into laser light has been demonstrated in this study. Parametric studies of the variation of laser mixture composition and laser gas temperature were carried out for CO2 and N2O gases. Theoretical analysis and modeling of the system have been performed. Reasonable agreement between predictions in the parameter variation and the experimental results have been obtained. Almost 200 mW of laser output at 10.6 micron was achieved by placing a small sapphire laser tube inside an oven at 1500 K the tube was filled with CO2 laser gas mixture and cooled by longitudinal nitrogen gas flow.

Surface patterning of multilayer graphene by ultraviolet laser irradiation in biomolecule sensing devices

NASA Astrophysics Data System (ADS)

Chang, Tien-Li; Chen, Zhao-Chi

2015-12-01

The study presents a direct process for surface patterning of multilayer graphene on the glass substrate as a biosensing device. In contrast to lithography with etching, the proposed process provides simultaneous surface patterning of multilayer graphene through nanosecond laser irradiation. In this study, the multilayer graphene was prepared by a screen printing process. Additionally, the wavelength of the laser beam was 355 nm. To perform the effective laser process with the small heat affected zone, the surface patterns on the sensing devices could be directly fabricated using the laser with optimal control of the pulse overlap at a fluence threshold of 0.63 J/cm2. The unique patterning of the laser-ablated surface exhibits their electrical and hydrophilic characteristics. The hydrophilic surface of graphene-based sensing devices was achieved in the process with the pulse overlap of 90%. Furthermore, the sensing devices for controlling the electrical response of glucose by using glucose oxidase can be used in sensors in commercial medical applications.

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...

Comparative Morphologic Evaluation and Occluding Effectiveness of Nd: YAG, CO2 and Diode Lasers on Exposed Human Dentinal Tubules: An Invitro SEM Study

PubMed Central

Grover, Harpreet Singh; Choudhary, Pankaj

2016-01-01

Introduction Dentinal hypersensitivity is one of the most common problem, encountered in dental practice but has least predictable treatment outcome. The advent of lasers in dentistry has provided an additional therapeutic option for treating dentinal hypersensitivity. Although various lasers have been tried over a period of time to treat dentinal hypersensitivity, but still the doubt persist as to which laser leads to maximum dentinal tubular occlusion and is most suitable with minimal hazardous effects. Aim To compare the effects of Nd: YAG, CO2 and 810-nm diode lasers on width of exposed dentinal tubule orifices and to evaluate the morphologic changes on dentinal surface of human tooth after laser irradiation by scanning electron microscope (SEM). Materials and Methods Forty root specimens were obtained from ten freshly extracted human premolars, which were randomly divided into four groups of ten each. Group I: control group treated with only saline, Group II: Nd:YAG laser, Group III: CO2 laser and Group IV: 810-nm diode laser. The specimens were examined using SEM. After calculating mean tubular diameter for each group, the values were compared statistically using parametric one-way ANOVA test and Turkey’s post hoc multiple comparison test. Results All the three lased groups showed a highly statistical significant result with p-value of <0.001 as compared to non-lased group. On intergroup comparison within the lased groups, all the three groups showed statistically significant difference in the reduction of dentinal tubular diameter (p-value < 0.001). Conclusion Nd: YAG laser was found to be most effective, followed by the CO2 laser and 810-nm diode laser was found to be least effective. The morphologic changes like craters, cracks and charring effect of the dentine were seen maximum by the use of CO2 laser. PMID:27630957

Comparative Morphologic Evaluation and Occluding Effectiveness of Nd: YAG, CO2 and Diode Lasers on Exposed Human Dentinal Tubules: An Invitro SEM Study.

PubMed

Saluja, Mini; Grover, Harpreet Singh; Choudhary, Pankaj

2016-07-01

Dentinal hypersensitivity is one of the most common problem, encountered in dental practice but has least predictable treatment outcome. The advent of lasers in dentistry has provided an additional therapeutic option for treating dentinal hypersensitivity. Although various lasers have been tried over a period of time to treat dentinal hypersensitivity, but still the doubt persist as to which laser leads to maximum dentinal tubular occlusion and is most suitable with minimal hazardous effects. To compare the effects of Nd: YAG, CO2 and 810-nm diode lasers on width of exposed dentinal tubule orifices and to evaluate the morphologic changes on dentinal surface of human tooth after laser irradiation by scanning electron microscope (SEM). Forty root specimens were obtained from ten freshly extracted human premolars, which were randomly divided into four groups of ten each. Group I: control group treated with only saline, Group II: Nd:YAG laser, Group III: CO2 laser and Group IV: 810-nm diode laser. The specimens were examined using SEM. After calculating mean tubular diameter for each group, the values were compared statistically using parametric one-way ANOVA test and Turkey's post hoc multiple comparison test. All the three lased groups showed a highly statistical significant result with p-value of <0.001 as compared to non-lased group. On intergroup comparison within the lased groups, all the three groups showed statistically significant difference in the reduction of dentinal tubular diameter (p-value < 0.001). Nd: YAG laser was found to be most effective, followed by the CO2 laser and 810-nm diode laser was found to be least effective. The morphologic changes like craters, cracks and charring effect of the dentine were seen maximum by the use of CO2 laser.

A practical comparison of Copper Bromide Laser for the treatment of vascular lesions.

PubMed

Lee, SunWoo; Lee, TaeBum; Kim, HoYoun; Kim, JungSoo; Eun, HyeJun; Kim, RyunKyung

2013-01-01

The recent rapid growth in demand for aesthetic non-invasive laser treatments such as unwanted skin rejuvenation, removal of age-related vascular blemishes has led to a boom in the medical devices to treat these conditions. Among diverse laser for skin treatment, copper bromide laser is a very effective, safe, and well tolerated treatment for facial telangiectasia at various energy levels and the most important thing of the copper bromide laser device is that the stability of the energy. However there is no evidence about effective copper bromide laser's energy level for the treatment of vascular lesions. We compared energy stability and treatment performance between two energy levels in 2 W and 8 W which commonly use in laser treatment for the vascular lesions. 8 W copper bromide laser was more stable compared than 2 W copper bromide laser. Also, 8 W copper bromide laser was effectively superior to 2 W copper bromide laser in treatment of vascular legion. Consequently, 8 W copper bromide laser treatment for vascular lesion might be more suitable than 2 W copper bromide laser.

Tunable single-longitudinal-mode operation of an injection-locked TEA CO2 laser. [ozone absorption spectroscopy

NASA Technical Reports Server (NTRS)

Megie, G.; Menzies, R. T.

1979-01-01

The tunable single-longitudinal-mode operation of a TEA CO2 laser by an injection technique using a CW waveguide laser as the master oscillator is reported. With the experimental arrangement described, in which the waveguide laser frequency is tuned to correspond to one of the oscillating longitudinal modes of the TEA laser, single-longitudinal-mode operation was achieved with no apparent reduction in the TEA output energy, on various CO2 lines with frequency offsets from the line center as large as 300 MHz. The capability of this technique for high-resolution spectroscopy or atmospheric lidar studies is demonstrated by the recording of the absorption spectrum of a strong ozone line.

Synthesis of arbitrary pulse waveforms in QCL-seeded ns-pulse CO₂ laser for optimization of an LPP EUV source.

PubMed

Nowak, Krzysztof M; Kurosawa, Yoshiaki; Suganuma, Takashi; Kawasuji, Yasufumi; Nakarai, Hiroaki; Saito, Takashi; Fujimoto, Junichi; Mizoguchi, Hakaru

2016-07-01

One of the unique features of the quantum-cascade-laser-seeded, nanosecond-pulse CO₂ laser, invented for the purpose of generation of extreme UV by laser-produced-plasma, is a robust synthesis of arbitrary pulse waveforms. In the present Letter we report on experimental results that are, to our best knowledge, the first demonstration of such functionality obtainable from nanosecond-pulse CO₂ laser technology. An online pulse duration adjustment within 10-40 ns was demonstrated, and a few exemplary pulse waveforms were synthesized, such as "tophat," "tailspike," and "leadspike" shapes. Such output characteristics may be useful to optimize the performance of LPP EUV source.

CO2 and Er:YAG laser interaction with grass tissues

NASA Astrophysics Data System (ADS)

Kim, Jaehun; Ki, Hyungson

2013-01-01

Plant leaves are multi-component optical materials consisting of water, pigments, and dry matter, among which water is the predominant constituent. In this article, we investigate laser interaction with grass using CO2 and Er:YAG lasers theoretically and experimentally, especially targeting water in grass tissues. We have first studied the optical properties of light absorbing constituents of grass theoretically, and then have identified interaction regimes and constructed interaction maps through a systematic experiment. Using the interaction maps, we have studied how interaction regimes change as process parameters are varied. This study reveals some interesting findings concerning carbonization and ablation mechanisms, the effect of laser beam diameter, and the ablation efficiency and quality of CO2 and Er:YAG lasers.

A sulfur hexafluoride sensor using quantum cascade and CO2 laser-based photoacoustic spectroscopy.

PubMed

Rocha, Mila; Sthel, Marcelo; Lima, Guilherme; da Silva, Marcelo; Schramm, Delson; Miklós, András; Vargas, Helion

2010-01-01

The increase in greenhouse gas emissions is a serious environmental problem and has stimulated the scientific community to pay attention to the need for detection and monitoring of gases released into the atmosphere. In this regard, the development of sensitive and selective gas sensors has been the subject of several research programs. An important greenhouse gas is sulphur hexafluoride, an almost non-reactive gas widely employed in industrial processes worldwide. Indeed it is estimated that it has a radiative forcing of 0.52 W/m(2). This work compares two photoacoustic spectrometers, one coupled to a CO(2) laser and another one coupled to a Quantum Cascade (QC) laser, for the detection of SF(6). The laser photoacoustic spectrometers described in this work have been developed for gas detection at small concentrations. Detection limits of 20 ppbv for CO(2) laser and 50 ppbv for quantum cascade laser were obtained.