Laser vaporization in treatment of superficial endometriosis of the uterine cervix

NASA Astrophysics Data System (ADS)

Wozniak, Jakub; Wilczak, Maciej; Opala, Tomasz; Pisarska-Krawczyk, Magdalena; Cwojdzinski, Marek; Pisarski, Tadeusz

1996-03-01

The study shows the treatment of superficial endometriosis of the uterine cervix in 79 patients. After first vaporization 74 patients were cured successfully. In two cases the laser procedure should be repeated and in 3 women the operation should be performed for the third time. All patients are still under control in our department and there is no recurrence observed. Carbon- dioxide laser vaporization under colposcopic control is an efficient method of treatment of superficial endometriosis of the uterine cervix that requires no anaesthesia. The healing process after laser procedures is fast and without complications. The number of recurrences is low. Use of carbon-dioxide laser under colposcopic control because of precise destruction of lesions, fast healing and a low number of recurrences seems to be the method of choice.

Double-Pulsed 2-micron Laser Transmitter for Multiple Lidar Applications

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Yu, Jirong

2002-01-01

A high energy double-pulsed Ho:Tm:YLF 2-micron laser amplifier has been demonstrated. 600 mJ per pulse pair under Q-switch operation is achieved with the gain of 4.4. This solid-state laser source can be used as lidar transmitter for multiple lidar applications such as coherent wind and carbon dioxide measurements.

Strong Optical Injection Locking of Edge-Emitting Lasers and Its Applications

DTIC Science & Technology

2006-08-18

investigated for communications applications. Using AlGaAs lasers, Kobayashi et al. demonstrated stable single-mode operation of Fabry - Perot (F-P...modulation (AM) efficiency is obtained at the expense of linearity. Furthermore, the previous gain-lever devices were Fabry - Perot (F-P) lasers operating in...coating of ~ 0.2-μm Zirconium dioxide (ZrO2) layer with a reflectivity of less than 0.1% is deposited on one facet to suppress the Fabry - Perot (F-P

Single Longitudinal Mode, High Repetition Rate, Q-switched Ho:YLF Laser for Remote Sensing

NASA Technical Reports Server (NTRS)

Bai, Yingxin; Yu, Jirong; Petzar, Paul; Petros, M.; Chen, Songsheng; Trieu, Bo; Lee, Nyung; Singh, U.

2009-01-01

Ho:YLF/LuLiF lasers have specific applications for remote sensing such as wind-speed measurement and carbon dioxide (CO2) concentration measurement in the atmosphere because the operating wavelength (around 2 m) is located in the eye-safe range and can be tuned to the characteristic lines of CO2 absorption and there is strong backward scattering signal from aerosol (Mie scattering). Experimentally, a diode pumped Ho:Tm:YLF laser has been successfully used as the transmitter of coherent differential absorption lidar for the measurement of with a repetition rate of 5 Hz and pulse energy of 75 mJ [1]. For highly precise CO2 measurements with coherent detection technique, a laser with high repetition rate is required to averaging out the speckle effect [2]. In addition, laser efficiency is critically important for the air/space borne lidar applications, because of the limited power supply. A diode pumped Ho:Tm:YLF laser is difficult to efficiently operate in high repetition rate due to the large heat loading and up-conversion. However, a Tm:fiber laser pumped Ho:YLF laser with low heat loading can be operated at high repetition rates efficiently [3]. No matter whether wind-speed or carbon dioxide (CO2) concentration measurement is the goal, a Ho:YLF/LuLiF laser as the transmitter should operate in a single longitudinal mode. Injection seeding is a valid technique for a Q-switched laser to obtain single longitudinal mode operation. In this paper, we will report the new results for a single longitudinal mode, high repetition rate, Q-switched Ho:YLF laser. In order to avoid spectral hole burning and make injection seeding easier, a four mirror ring cavity is designed for single longitudinal mode, high repetition rate Q-switched Ho:YLF laser. The ramp-fire technique is chosen for injection seeding.

Laser surgery: using the carbon dioxide laser.

PubMed Central

Wright, V. C.

1982-01-01

In 1917 Einstein theorized tha through an atomic process a unique kind of electromagnetic radiation could be produced by stimulated emission. When such radiation is in the optical or infrared spectrum it is termed laser (light amplification by stimulated emission of radiation) light. A laser, a high-intensity light source, emits a nearly parallel electromagnetic beam of energy at a given wavelength that can be captured by a lens and concentrated in the focal spot. The wavelength determines how the laser will be used. The carbon dioxide laser is now successfully employed for some surgical procedures in gynecology, otorhinolaryngology, neurosurgery, and plastic and general surgery. The CO2 laser beam is directed through the viewing system of an operating microscope or through a hand-held laser component. Its basic action in tissue is thermal vaporization; it causes minimal damage to adjacent tissues. Surgeons require special training in the basic methods and techniques of laser surgery, as well as in the safety standards that must be observed. Images FIG. 5 PMID:7074503

A Miniaturized Laser Heterodyne Radiometer for Greenhouse Gas Measurements in the Atmospheric Column

NASA Technical Reports Server (NTRS)

Steel, Emily Wilson

2015-01-01

Laser Heterodyne Radiometry is a technique adapted from radio receiver technology has been used to measure trace gases in the atmosphere since the 1960s.By leveraging advances in the telecommunications industry, it has been possible to miniaturize this technology.The mini-LHR (Miniaturized Laser Heterodyne Radiometer) has been under development at NASA Goddard Space flight Center since 2009. This sun-viewing instrument measures carbon dioxide and methane in the atmospheric column and operates in tandem with an AERONET sun photometer producing a simultaneous measure of aerosols. The mini-LHR has been extensively field tested in a range of locations ranging in the continental US as well as Alaska and Hawaii and now operates autonomously with sensitivities of approximately 0.2 ppmv and approximately10 ppbv, for carbon dioxide and methane respectively, for 10 averaged scans under clear sky conditions.

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.

Applications of lasers and electro-optics

NASA Astrophysics Data System (ADS)

Tan, B. C.; Low, K. S.; Chen, Y. H.; Ahmad, Harith; Tou, T. Y.

Supported by the IRPA Programme on Laser Technology and Applications, many types of lasers have been designed, constructed and applied in various areas of science, medicine and industries. Amongst these lasers constructed were high power carbon dioxide lasers, rare gas halide excimer lasers, solid state Neodymium-YAG lasers, nitrogen lasers, flashlamp pumped dye lasers and nitrogen and excimer laser pumped dye lasers. These lasers and the associated electro-optics system, some with computer controlled, are designed and developed for the following areas of applications: (1) industrial applications of high power carbon dioxide lasers for making of i.c. components and other materials processing purposes -- prototype operational systems have been developed; (2) Medical applications of lasers for cancer treatment using the technique of photodynamic therapy -- a new and more effective treatment protocol has been proposed; (3) agricultural applications of lasers in palm oil and palm fruit-fluorescence diagnostic studies -- fruit ripeness signature has been developed and palm oil oxidation level were investigated; (4) development of atmospheric pollution monitoring systems using laser lidar techniques -- laboratory scale systems were developed; and (5) other applications of lasers including laser holographic and interferometric methods for the non destructive testing of materials.

Pulsed TEA CO2 Laser Irradiation of Titanium in Nitrogen and Carbon Dioxide Gases

NASA Astrophysics Data System (ADS)

Ciganovic, J.; Matavulj, P.; Trtica, M.; Stasic, J.; Savovic, J.; Zivkovic, S.; Momcilovic, M.

2017-12-01

Surface changes created by interaction of transversely excited atmospheric carbon dioxide (TEA CO2) laser with titanium target/implant in nitrogen and carbon dioxide gas were studied. TEA CO2 laser operated at 10.6 μm, pulse length of 100 ns and fluence of ˜17 J/cm2 which was sufficient for inducing surface modifications. Induced changes depend on the gas used. In both gases the grain structure was produced (central irradiated zone) but its forms were diverse, (N2: irregular shape; CO2: hill-like forms). Hydrodynamic features at peripheral zone, like resolidified droplets, were recorded only in CO2 gas. Elemental analysis of the titanium target surface indicated that under a nitrogen atmosphere surface nitridation occurred. In addition, irradiation in both gases was followed by appearance of plasma in front of the target. The existence of plasma indicates relatively high temperatures created above the target surface offering a sterilizing effect.

Infrared Spectroscopic Measurement of Titanium Dioxide Nanoparticle Shallow Trap State Energies

DTIC Science & Technology

2010-02-10

energy from the immediately preceding pulse burst. Continuous operation of a laser directed onto a target leads to vaporization operation. In this...1988, (92), 5196-5201. 93. Wang, Y.; Herron, N., Quantum Size Effects on the Exciton Energy of Cds Clusters . Physical Review B 1990, 42 (11...Nanoparticles by Pulsed Laser Ablation: Ambient Pressure Dependence of Crystallization. Jpn. J. Appl. Phys. 2003, 42, L 479–L 481. 186. Kawasaki, K.; Despres, J

Solid-State 2-Micron Laser Transmitter Advancement for Wind and Carbon Dioxide Measurements From Ground, Airborne, and Space-Based Lidar Systems

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Kavaya, Michael J.; Koch, Grady; Yu, Jirong; Ismail, Syed

2008-01-01

NASA Langley Research Center has been developing 2-micron lidar technologies over a decade for wind measurements, utilizing coherent Doppler wind lidar technique and carbon dioxide measurements, utilizing Differential Absorption Lidar (DIAL) technique. Significant advancements have been made towards developing state-of-the-art technologies towards laser transmitters, detectors, and receiver systems. These efforts have led to the development of solid-state lasers with high pulse energy, tunablility, wavelength-stability, and double-pulsed operation. This paper will present a review of these technological developments along with examples of high resolution wind and high precision CO2 DIAL measurements in the atmosphere. Plans for the development of compact high power lasers for applications in airborne and future space platforms for wind and regional to global scale measurement of atmospheric CO2 will also be discussed.

Optical-fiber-to-waveguide coupling using carbon-dioxide-laser-induced long-period fiber gratings.

PubMed

Bachim, Brent L; Ogunsola, Oluwafemi O; Gaylord, Thomas K

2005-08-15

Optical fibers are expected to play a role in chip-level and board-level optical interconnects because of limitations on the bandwidth and level of integration of electrical interconnects. Therefore, methods are needed to couple optical fibers directly to waveguides on chips and on boards. We demonstrate optical-fiber-to-waveguide coupling using carbon-dioxide laser-induced long-period fiber gratings (LPFGs). Such gratings can be written in standard fiber and offer wavelength multiplexing-demultiplexing performance. The coupler fabrication process and the characterization apparatus are presented. The operation and the wavelength response of a LPFG-based optical-fiber-to-waveguide directional coupler are demonstrated.

The 2014 ASCENDS Field Campaign - a Carbon Dioxide Laser Absorption Spectrometer Perspective

NASA Astrophysics Data System (ADS)

Spiers, G. D.; Menzies, R. T.; Jacob, J. C.; Geier, S.; Fregoso, S. F.

2014-12-01

NASA's ASCENDS mission has been flying several candidate lidar instruments on board the NASA DC-8 aircraft to obtain column integrated measurements of Carbon Dioxide. Each instrument uses a different approach to making the measurement and combined they have allowed for the informed development of the ASCENDS mission measurement requirements(1). The JPL developed Carbon Dioxide Laser Absorption Spectrometer, CO2LAS is one of these instruments. The CO2LAS measures the weighted, column averaged carbon dioxide between the aircraft and the ground using a continuous-wave heterodyne technique. The instrument operates at a 2.05 micron wavelength optimized for enhancing sensitivity to boundary layer carbon dioxide. Since the 2013 field campaign the instrument has undergone significant upgrades that improve the data collection efficiency and instrument stability and has recently been re-integrated onto the NASA DC-8 for the August 2014 ASCENDS field campaign. This presentation will summarize the instrument and algorithm improvements and review the 2014 field campaign flights and preliminary results. (1) Abshire, J.B. et al., "An overview of NASA's ASCENDS Mission lidar measurement requirements", submitted to 2014 Fall AGU Conference.

Aerodynamic levitator for in situ x-ray structure measurements on high temperature and molten nuclear fuel materials

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

Weber, J. K. R.; Alderman, O. L. G.; Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439

2016-07-15

An aerodynamic levitator with carbon dioxide laser beam heating was integrated with a hermetically sealed controlled atmosphere chamber and sample handling mechanism. The system enabled containment of radioactive samples and control of the process atmosphere chemistry. The chamber was typically operated at a pressure of approximately 0.9 bars to ensure containment of the materials being processed. Samples 2.5-3 mm in diameter were levitated in flowing gas to achieve containerless conditions. Levitated samples were heated to temperatures of up to 3500 °C with a partially focused carbon dioxide laser beam. Sample temperature was measured using an optical pyrometer. The sample environment wasmore » integrated with a high energy (100 keV) x-ray synchrotron beamline to enable in situ structure measurements to be made on levitated samples as they were heated, melted, and supercooled. The system was controlled from outside the x-ray beamline hutch by using a LabVIEW program. Measurements have been made on hot solid and molten uranium dioxide and binary uranium dioxide-zirconium dioxide compositions.« less

Aerodynamic levitator for in situ x-ray structure measurements on high temperature and molten nuclear fuel materials

DOE PAGES

Weber, J. K. R.; Tamalonis, A.; Benmore, C. J.; ...

2016-07-01

We integrated an aerodynamic levitator with carbon dioxide laser beam heating with a hermetically sealed controlled atmosphere chamber and sample handling mechanism. The system enabled containment of radioactive samples and control of the process atmosphere chemistry. Furthermore, the chamber was typically operated at a pressure of approximately 0.9 bars to ensure containment of the materials being processed. Samples 2.5-3 mm in diameter were levitated in flowing gas to achieve containerless conditions. Levitated samples were heated to temperatures of up to 3500 °C with a partially focused carbon dioxide laser beam. Sample temperature was measured using an optical pyrometer. The samplemore » environment was integrated with a high energy (100 keV) x-ray synchrotron beamline to enable in situ structure measurements to be made on levitated samples as they were heated, melted, and supercooled. Our system was controlled from outside the x-ray beamline hutch by using a LabVIEW program. Measurements have been made on hot solid and molten uranium dioxide and binary uranium dioxide-zirconium dioxide compositions.« less

Comparison of carbon dioxide laser-assisted versus stapler-assisted endoscopic cricopharyngeal myotomy.

PubMed

Pollei, Taylor R; Hinni, Michael L; Hayden, Richard E; Lott, David G; Mors, Matthew B

2013-09-01

We directly compared endoscopic carbon dioxide (CO2) laser and stapler treatment methods for both cricopharyngeal hypertrophy (CPH) and Zenker's diverticulum (ZD). We performed a single-institution retrospective chart review of 153 patients who underwent either CO2 laser-assisted or stapler-assisted endoscopic cricopharyngeal myotomy (CPM). Isolated CPH was more likely to be treated with the CO2 laser than by stapler techniques. The ZD pouch size decreased significantly after surgery in both laser (p = 0.04) and stapler (p = 0.008) groups. The average duration of the procedure for CPM was longer for the laser than for the stapler (p = 0.01). Both techniques were successful when used in revision procedures. The overall complication rates were not statistically significantly different. Laser surgery trended toward a higher rate of major complications (2.4% versus 0%). Symptomatic recurrence was more likely after stapler surgery (p = 0.002). The rates of revision surgery were similar in the two groups (3.3% for laser and 4.3% for stapler). In the treatment of isolated CPH or ZD, stapler-assisted endoscopic surgery results in a shorter operative time, whereas laser-assisted CPM results in a decreased incidence of symptomatic recurrence.

Development of CO2 laser Doppler instrumentation for detection of clear air turbulence, volume 1

NASA Technical Reports Server (NTRS)

Harris, C. E.; Jelalian, A. V.

1979-01-01

Modification, construction, test and operation of an advanced airborne carbon dioxide laser Doppler system for detecting clear air turbulence are described. The second generation CAT program and those auxiliary activities required to support and verify such a first-of-a-kind system are detailed: aircraft interface; ground and flight verification tests; data analysis; and laboratory examinations.

Progress in Measurement of Carbon Dioxide Using a Broadband Lidar

NASA Technical Reports Server (NTRS)

Heaps, William S.

2010-01-01

In order to better understand the budget of carbon dioxide in the Earth's atmosphere it is necessary to develop a global high precision understanding of the carbon dioxide column. In order to uncover the 'missing sink" that is responsible for the large discrepancies in the budget as we presently understand it calculation has indicated that measurement accuracy on the order of 1 ppm is necessary. Because typical column average CO2 has now reached 380 ppm this represents a precision on the order of .25% for these column measurements. No species has ever been measured from space at such a precision. In recognition of the importance of understanding the CO2 budget in order to evaluate its impact on global warming the National Research Council in its decadal survey report to NASA recommended planning for a laser based total CO2 mapping mission in the near future. The extreme measurement accuracy requirements on this mission places very strong requirements on the laser system used for the measurement. This work presents an overview of the characteristics necessary in a laser system used to make this measurement. Consideration is given to the temperature dependence, pressure broadening, and pressure shift of the CO2 lines themselves and how these impact the laser system characteristics We have been examining the possibility of making precise measurements of atmospheric carbon dioxide using broad band source of radiation. This means that many of the difficulties in wavelength control can be treated in the detector portion of the system rather than the laser source. It also greatly reduces the number of individual lasers required to make a measurement. Simplifications such as these are extremely desirable for systems designed to operate from space.

21 CFR 874.4500 - Ear, nose, and throat microsurgical carbon dioxide laser.

Code of Federal Regulations, 2011 CFR

2011-04-01

... laser. 874.4500 Section 874.4500 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND..., nose, and throat microsurgical carbon dioxide laser. (a) Identification. An ear, nose, and throat microsurgical carbon dioxide laser is a device intended for the surgical excision of tissue from the ear, nose...

21 CFR 874.4500 - Ear, nose, and throat microsurgical carbon dioxide laser.

Code of Federal Regulations, 2010 CFR

2010-04-01

... laser. 874.4500 Section 874.4500 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND..., nose, and throat microsurgical carbon dioxide laser. (a) Identification. An ear, nose, and throat microsurgical carbon dioxide laser is a device intended for the surgical excision of tissue from the ear, nose...

21 CFR 874.4500 - Ear, nose, and throat microsurgical carbon dioxide laser.

Code of Federal Regulations, 2013 CFR

2013-04-01

... laser. 874.4500 Section 874.4500 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND..., nose, and throat microsurgical carbon dioxide laser. (a) Identification. An ear, nose, and throat microsurgical carbon dioxide laser is a device intended for the surgical excision of tissue from the ear, nose...

21 CFR 874.4500 - Ear, nose, and throat microsurgical carbon dioxide laser.

Code of Federal Regulations, 2012 CFR

2012-04-01

... laser. 874.4500 Section 874.4500 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND..., nose, and throat microsurgical carbon dioxide laser. (a) Identification. An ear, nose, and throat microsurgical carbon dioxide laser is a device intended for the surgical excision of tissue from the ear, nose...

21 CFR 874.4500 - Ear, nose, and throat microsurgical carbon dioxide laser.

Code of Federal Regulations, 2014 CFR

2014-04-01

... laser. 874.4500 Section 874.4500 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND..., nose, and throat microsurgical carbon dioxide laser. (a) Identification. An ear, nose, and throat microsurgical carbon dioxide laser is a device intended for the surgical excision of tissue from the ear, nose...

Characterization of the surfaces of platinum/tin oxide based catalysts by Fourier transform spectroscopy (FTIR)

NASA Technical Reports Server (NTRS)

Keiser, Joseph T.

1989-01-01

The Laser Atmospheric Wind Sounder (LAWS) Program has as one of its goals the development of a satellite based carbon dioxide laser for making wind velocity measurements. The specifications for this laser include the requirement that the laser operate at a repetition rate of 10 Hertz continuously for three years. Earth-based carbon dioxide lasers can operate for only a short time on a single charge of gas because the lasing action causes the CO2 to break down into CO and O2. Therefore, earth-based CO2 lasers are generally operated in a flow through mode in which the spent gas is continually exhausted and fresh gas is continually added. For a satellite based system, however, a recirculation system is desired because it is not practical to send up extra tanks of CO2. A catalyst which could enable a recirculating CO2 laser to function continuously for three years needs to be developed. In the development of a catalyst system there are many variables. Obviously, not all possible formulations can be tested for three years, therefore, an accurate model which is based on the reaction mechanism is needed. The construction of a multistep reaction mechanism is similar to the construction of a jigsaw puzzle. Different techniques each supply a piece of the puzzle and the researcher must put the pieces together. Transmission infrared spectroscopy was shown to be very useful in supplying some of the information needed to elucidate reaction mechanisms. The purpose was to see what kind of information might be obtained about the NASA catalyst using infrared absorption spectroscopy. Approximately 200 infrared spectra of the prototype Pt/tin oxide catalyst and its precursor components are observed under a variety of different conditions. The most significant observations are summarized.

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

PubMed Central

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

2011-01-01

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

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

PubMed

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

2011-07-01

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

Development of Double-Pulsed Two-Micron Laser for Atmospheric Carbon Dioxide Measurements

NASA Technical Reports Server (NTRS)

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

2017-01-01

A CO2 lidar double-pulse two-micron high-energy transmitter, tuned to on- and off-line absorption wavelengths, has been developed. Transmitter operation and performance has been verified on ground and airborne platform.

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

Endoscopic Carbon Dioxide Laser Photocoagulation Of Bleeding Canine Gastric Ulcers

NASA Astrophysics Data System (ADS)

Gal, Dov; Ron, Nimrod; Orgad, Uri; Katzir, Abraham

1987-04-01

This is the first report which describes carbon dioxide laser photocoagulation of upper gastrointestinal bleeding via a flexible endoscope, using an infrared transmitting siver nalide fiber. Various laser parameters were checked to determine the optimal conditions for hemostasis. Both the acute effects of laser irradiation on tissue and the chronic effects on healing process were examined. Preliminary results indicate that carbon dioxide laser beam can successfully photocoagulate moderately bleeding ulcers.

Closed-Cycle, Frequency-Stable CO2 Laser Technology

NASA Technical Reports Server (NTRS)

Batten, Carmen E. (Editor); Miller, Irvin M. (Editor); Wood, George M., Jr. (Editor); Willetts, David V. (Editor)

1987-01-01

These proceedings contain a collection of papers and comments presented at a workshop on technology associated with long-duration closed-cycle operation of frequency-stable, pulsed carbon dioxide lasers. This workshop was held at the NASA Langley Research Center June 10 to 12, 1986. The workshop, jointly sponsored by the National Aeronautics and Space Administration (NASA) and the Royal Signals and Radar Establishment (RSRE), was attended by 63 engineers and scientists from the United States and the United Kingdom. During the 2 1/2 days of the workshop, a number of issues relating to obtaining frequency-stable operation and to the catalytic control of laser gas chemistry were discussed, and specific recommendations concerning future activities were drafted.

Lidar detection of carbon dioxide in volcanic plumes

NASA Astrophysics Data System (ADS)

Fiorani, Luca; Santoro, Simone; Parracino, Stefano; Maio, Giovanni; Del Franco, Mario; Aiuppa, Alessandro

2015-06-01

Volcanic gases give information on magmatic processes. In particular, anomalous releases of carbon dioxide precede volcanic eruptions. Up to now, this gas has been measured in volcanic plumes with conventional measurements that imply the severe risks of local sampling and can last many hours. For these reasons and for the great advantages of laser sensing, the thorough development of volcanic lidar has been undertaken at the Diagnostics and Metrology Laboratory (UTAPRAD-DIM) of the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA). In fact, lidar profiling allows one to scan remotely volcanic plumes in a fast and continuous way, and with high spatial and temporal resolution. Two differential absorption lidar instruments will be presented in this paper: BILLI (BrIdge voLcanic LIdar), based on injection seeded Nd:YAG laser, double grating dye laser, difference frequency mixing (DFM) and optical parametric amplifier (OPA), and VULLI (VULcamed Lidar), based on injection seeded Nd:YAG laser and optical parametric oscillator (OPO). The first one is funded by the ERC (European Research Council) project BRIDGE and the second one by the ERDF (European Regional Development Fund) project VULCAMED. While VULLI has not yet been tested in a volcanic site, BILLI scanned the gas emitted by Pozzuoli Solfatara (Campi Flegrei volcanic area, Naples, Italy) during a field campaign carried out from 13 to 17 October 2014. Carbon dioxide concentration maps were retrieved remotely in few minutes in the crater area. Lidar measurements were in good agreement with well-established techniques, based on different operating principles. To our knowledge, it is the first time that carbon dioxide in a volcanic plume is retrieved by lidar, representing the first direct measurement of this kind ever performed on an active volcano and showing the high potential of laser remote sensing in geophysical research.

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.

Technology Advancements for Active Remote Sensing of Carbon Dioxide from Space using the ASCENDS CarbonHawk Experiment Simulator

NASA Astrophysics Data System (ADS)

Obland, M. D.; Nehrir, A. R.; Liu, Z.; Chen, S.; Campbell, J. F.; Lin, B.; Kooi, S. A.; Fan, T. F.; Choi, Y.; Plant, J.; Yang, M. M.; Browell, E. V.; Harrison, F. W.; Meadows, B.; Dobler, J. T.; Zaccheo, T. S.

2015-12-01

This work describes advances in critical lidar technologies and techniques developed as part of the ASCENDS CarbonHawk Experiment Simulator (ACES) system for measuring atmospheric column carbon dioxide (CO2) mixing ratios in support of the NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission. The ACES design demonstrates advancements in: (1) enhanced power-aperture product through the use and operation of multiple co-aligned laser transmitters and a multi-aperture telescope design; (2) high-efficiency, high-power Erbium-Doped Fiber Amplifiers (EDFAs); (3) high-bandwidth, low-noise HgCdTe detector and transimpedence amplifier (TIA) subsystem capable of long-duration operation; and (4) advanced algorithms for cloud and aerosol discrimination. The ACES instrument, an Intensity-Modulated Continuous-Wave (IM-CW) lidar, was designed for high-altitude aircraft operations and can be directly applied to space instrumentation to meet the ASCENDS mission requirements. Specifically, the lidar simultaneously transmits three IM-CW laser beams from the high power EDFAs operating near 1571 nm. The outgoing laser beams are aligned to the field of view of three fiber-coupled 17.8-cm diameter telescopes, and the backscattered light collected by the same three telescopes is sent to the detector/TIA subsystem, which has a bandwidth of 4.9 MHz and operates service-free with a tactical Dewar and cryocooler. The electronic bandwidth is only slightly higher than 1 MHz, effectively limiting the noise level. Two key laser modulation approaches are being tested to significantly mitigate the effects of thin clouds on the retrieved CO2 column amounts. This work provides an over view of these technologies, the modulation approaches, and results from recent test flights.

Technology Advancements for Active Remote Sensing of Carbon Dioxide From Space using the ASCENDS CarbonHawk Experiment Simulator

NASA Astrophysics Data System (ADS)

Obland, M. D.; Liu, Z.; Campbell, J. F.; Lin, B.; Kooi, S. A.; Carrion, W.; Hicks, J.; Fan, T. F.; Nehrir, A. R.; Browell, E. V.; Meadows, B.; Davis, K. J.

2016-12-01

This work describes advances in critical lidar technologies and techniques developed as part of the ASCENDS CarbonHawk Experiment Simulator (ACES) system for measuring atmospheric column carbon dioxide (CO2) mixing ratios in support of the NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission. The ACES design demonstrates advancements in: (1) enhanced power-aperture product through the use and operation of multiple co-aligned laser transmitters and a multi-aperture telescope design; (2) high-efficiency, high-power Erbium-Doped Fiber Amplifiers (EDFAs); (3) high-bandwidth, low-noise HgCdTe detector and transimpedence amplifier (TIA) subsystem capable of long-duration operation; and (4) advanced algorithms for cloud and aerosol discrimination. The ACES instrument, an Intensity-Modulated Continuous-Wave (IM-CW) lidar, was designed for high-altitude aircraft operations and can be directly applied to space instrumentation to meet the ASCENDS mission requirements. Specifically, the lidar simultaneously transmits three IM-CW laser beams from the high power EDFAs operating near 1571 nm. The outgoing laser beams are aligned to the field of view of three fiber-coupled 17.8-cm diameter telescopes, and the backscattered light collected by the same three telescopes is sent to the detector/TIA subsystem, which has a bandwidth of 4.9 MHz and operates service-free with a tactical Dewar and cryocooler. The electronic bandwidth is only slightly higher than 1 MHz, effectively limiting the noise level. Two key laser modulation approaches are being tested to significantly mitigate the effects of thin clouds on the retrieved CO2 column amounts. This work provides an over view of these technologies, the modulation approaches, and results from recent test flights during the Atmospheric Carbon and Transport - America (ACT-America) Earth Venture Suborbital flight campaign.

Double-Pulse Two-Micron IPDA Lidar Simulation for Airborne Carbon Dioxide Measurements

NASA Technical Reports Server (NTRS)

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

2015-01-01

An advanced double-pulsed 2-micron integrated path differential absorption lidar has been developed at NASA Langley Research Center for measuring atmospheric carbon dioxide. The instrument utilizes a state-of-the-art 2-micron laser transmitter with tunable on-line wavelength and advanced receiver. Instrument modeling and airborne simulations are presented in this paper. Focusing on random errors, results demonstrate instrument capabilities of performing precise carbon dioxide differential optical depth measurement with less than 3% random error for single-shot operation from up to 11 km altitude. This study is useful for defining CO2 measurement weighting, instrument setting, validation and sensitivity trade-offs.

Infrared image construction with computer-generated reflection holograms. [using carbon dioxide laser

NASA Technical Reports Server (NTRS)

Angus, J. C.; Coffield, F. E.; Edwards, R. V.; Mann, J. A., Jr.; Rugh, R. W.; Gallagher, N. C.

1977-01-01

Computer-generated reflection holograms hold substantial promise as a means of carrying out complex machining, marking, scribing, welding, soldering, heat treating, and similar processing operations simultaneously and without moving the work piece or laser beam. In the study described, a photographically reduced transparency of a 64 x 64 element Lohmann hologram was used to make a mask which, in turn, was used (with conventional photoresist techniques) to produce a holographic reflector. Images from a commercial CO2 laser (150W TEM(00)) and the holographic reflector are illustrated and discussed.

Development and Deployment of a Compact Eye-Safe Scanning Differential absorption Lidar (DIAL) for Spatial Mapping of Carbon Dioxide for Monitoring/Verification/Accounting at Geologic Sequestration Sites

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

Repasky, Kevin

2014-03-31

A scanning differential absorption lidar (DIAL) instrument for monitoring carbon dioxide has been developed. The laser transmitter uses two tunable discrete mode laser diodes (DMLD) operating in the continuous wave (cw) mode with one locked to the online absorption wavelength and the other operating at the offline wavelength. Two in-line fiber optic switches are used to switch between online and offline operation. After the fiber optic switch, an acousto- optic modulator (AOM) is used to generate a pulse train used to injection seed an erbium doped fiber amplifier (EDFA) to produce eye-safe laser pulses with maximum pulse energies of 66more » {micro}J, a pulse repetition frequency of 15 kHz, and an operating wavelength of 1.571 {micro}m. The DIAL receiver uses a 28 cm diameter Schmidt-Cassegrain telescope to collect that backscattered light, which is then monitored using a photo-multiplier tube (PMT) module operating in the photon counting mode. The DIAL instrument has been operated from a laboratory environment on the campus of Montana State University, at the Zero Emission Research Technology (ZERT) field site located in the agricultural research area on the western end of the Montana State University campus, and at the Big Sky Carbon Sequestration Partnership site located in north-central Montana. DIAL data has been collected and profiles have been validated using a co-located Licor LI-820 Gas Analyzer point sensor.« less

Computer Simulation of Global Profiles of Carbon Dioxide Using a Pulsed, 2-Micron, Coherent-Detection, Column-Content DIAL System

NASA Technical Reports Server (NTRS)

Kavaya, Michael J.; Singh, Upendra N.; Koch, Grady J.; Yu, Jirong; Frehlich, Rod G.

2009-01-01

We present preliminary results of computer simulations of the error in measuring carbon dioxide mixing ratio profiles from earth orbit. The simulated sensor is a pulsed, 2-micron, coherent-detection lidar alternately operating on at least two wavelengths. The simulated geometry is a nadir viewing lidar measuring the column content signal. Atmospheric absorption is modeled using FASCODE3P software with the HITRAN 2004 absorption line data base. Lidar shot accumulation is employed up to the horizontal resolution limit. Horizontal resolutions of 50, 100, and 200 km are shown. Assuming a 400 km spacecraft orbit, the horizontal resolutions correspond to measurement times of about 7, 14, and 28 s. We simulate laser pulse-pair repetition frequencies from 1 Hz to 100 kHz. The range of shot accumulation is 7 to 2.8 million pulse-pairs. The resultant error is shown as a function of horizontal resolution, laser pulse-pair repetition frequency, and laser pulse energy. The effect of different on and off pulse energies is explored. The results are compared to simulation results of others and to demonstrated 2-micron operating points at NASA Langley.

Infrared diagnosis using liquid crystal detectors

NASA Technical Reports Server (NTRS)

Hugenschmidt, M.; Vollrath, K.

1986-01-01

The possible uses of pulsed carbon dioxide lasers for analysis of plasmas and flows need appropriate infrared image converters. Emphasis was placed on liquid crystal detectors and their operational modes. Performance characterstics and selection criteria, such as high sensitivity, short reaction time, and high spatial resolution are discussed.

Use Of Zernike Polynomials And Interferometry In The Optical Design And Assembly Of Large Carbon-Dioxide Laser Systems

NASA Astrophysics Data System (ADS)

Viswanathan, V. K.

1982-02-01

This paper describes the need for non-raytracing schemes in the optical design and analysis of large carbon-dioxide lasers like the Gigawatt,1 Gemini, 2 and Helios3 lasers currently operational at Los Alamos, and the Antares 4 laser fusion system under construction. The scheme currently used at Los Alamos involves characterizing the various optical components with a Zernike polynomial sets obtained by the digitization6 of experimentally produced interferograms of the components. A Fast Fourier Transform code then propagates the complex amplitude and phase of the beam through the whole system and computes the optical parameters of interest. The analysis scheme is illustrated through examples of the Gigawatt, Gemini, and Helios systems. A possible way of using the Zernike polynomials in optical design problems of this type is discussed. Comparisons between the computed values and experimentally obtained results are made and it is concluded that this appears to be a valid approach. As this is a review article, some previously published results are also used where relevant.

Color vision deficits and laser eyewear protection for soft tissue laser applications.

PubMed

Teichman, J M; Vassar, G J; Yates, J T; Angle, B N; Johnson, A J; Dirks, M S; Thompson, I M

1999-03-01

Laser safety considerations require urologists to wear laser eye protection. Laser eye protection devices block transmittance of specific light wavelengths and may distort color perception. We tested whether urologists risk color confusion when wearing laser eye protection devices for laser soft tissue applications. Subjects were tested with the Farnsworth-Munsell 100-Hue Test without (controls) and with laser eye protection devices for carbon dioxide, potassium titanyl phosphate (KTP), neodymium (Nd):YAG and holmium:YAG lasers. Color deficits were characterized by error scores, polar graphs, confusion angles, confusion index, scatter index and color axes. Laser eye protection device spectral transmittance was tested with spectrophotometry. Mean total error scores plus or minus standard deviation were 13+/-5 for controls, and 44+/-31 for carbon dioxide, 273+/-26 for KTP, 22+/-6 for Nd:YAG and 14+/-8 for holmium:YAG devices (p <0.001). The KTP laser eye protection polar graphs, and confusion and scatter indexes revealed moderate blue-yellow and red-green color confusion. Color axes indicated no significant deficits for controls, or carbon dioxide, Nd:YAG or holmium:YAG laser eye protection in any subject compared to blue-yellow color vision deficits in 8 of 8 tested with KTP laser eye protection (p <0.001). Spectrophotometry demonstrated that light was blocked with laser eye protection devices for carbon dioxide less than 380, holmium:YAG greater than 850, Nd:YAG less than 350 and greater than 950, and KTP less than 550 and greater than 750 nm. The laser eye protection device for KTP causes significant blue-yellow and red-green color confusion. Laser eye protection devices for carbon dioxide, holmium:YAG and Nd:YAG cause no significant color confusion compared to controls. The differences are explained by laser eye protection spectrophotometry characteristics and visual physiology.

Rapid and Selective Removal of Composite From Tooth Surfaces With a 9.3 μm CO2 Laser Using Spectral Feedback

PubMed Central

Chan, Kenneth H.; Hirasuna, Krista; Fried, Daniel

2015-01-01

Objective Dental composite restorative materials are color matched to the tooth and are difficult to remove by mechanical means without excessive removal or damage to peripheral enamel and dentin. Lasers are ideally suited for selective ablation to minimize healthy tissue loss when replacing existing restorations, sealants, or removing composite adhesives such as residual composite left after debonding orthodontic brackets. Methods In this study, a carbon dioxide laser operating at 9.3-μm with a pulse duration of 10–20-microsecond and a pulse repetition rate of ~200 Hz was integrated with a galvanometer based scanner and used to selectively remove composite from tooth surfaces. Spectra of the plume emission were acquired after each laser pulse and used to differentiate between the ablation of dental enamel or composite. Microthermocouples were used to monitor the temperature rise in the pulp chamber during composite removal. The composite was placed on tooth buccal and occlusal surfaces and the carbon dioxide laser beam was scanned across the surface to selectively remove the composite without excessive damage to the underlying sound enamel. The residual composite and the damage to the underlying enamel was evaluated using optical microscopy. Results The laser was able to rapidly remove composite from tooth buccal and occlusal surfaces with minimal damage to the underlying sound enamel and without excessive heat accumulation in the tooth. Conclusion This study demonstrated that composite can be selectively removed from tooth surfaces at clinically relevant rates using a CO2 laser operating at 9.3-μm with high pulse repetition rates with minimal heat deposition and damage to the underlying enamel. PMID:21956630

Rapid and selective removal of composite from tooth surfaces with a 9.3 µm CO2 laser using spectral feedback.

PubMed

Chan, Kenneth H; Hirasuna, Krista; Fried, Daniel

2011-09-01

Dental composite restorative materials are color matched to the tooth and are difficult to remove by mechanical means without excessive removal or damage to peripheral enamel and dentin. Lasers are ideally suited for selective ablation to minimize healthy tissue loss when replacing existing restorations, sealants, or removing composite adhesives such as residual composite left after debonding orthodontic brackets. In this study, a carbon dioxide laser operating at 9.3-µm with a pulse duration of 10-20-microsecond and a pulse repetition rate of ∼200 Hz was integrated with a galvanometer based scanner and used to selectively remove composite from tooth surfaces. Spectra of the plume emission were acquired after each laser pulse and used to differentiate between the ablation of dental enamel or composite. Microthermocouples were used to monitor the temperature rise in the pulp chamber during composite removal. The composite was placed on tooth buccal and occlusal surfaces and the carbon dioxide laser beam was scanned across the surface to selectively remove the composite without excessive damage to the underlying sound enamel. The residual composite and the damage to the underlying enamel was evaluated using optical microscopy. The laser was able to rapidly remove composite from tooth buccal and occlusal surfaces with minimal damage to the underlying sound enamel and without excessive heat accumulation in the tooth. This study demonstrated that composite can be selectively removed from tooth surfaces at clinically relevant rates using a CO(2) laser operating at 9.3-µm with high pulse repetition rates with minimal heat deposition and damage to the underlying enamel. Copyright © 2011 Wiley-Liss, Inc.

Development of carbon dioxide laser doppler instrumentation detection of clear air turbulence

NASA Technical Reports Server (NTRS)

Sonnenschein, C.; Jelalian, A.; Keene, W.

1970-01-01

The analytical, experimental, and developmental aspects of an airborne, pulsed, carbon dioxide laser-optical radar system are described. The laser detects clear air turbulence and performs Doppler measurements of this air-motion phenomenon. Conclusions and recommendations arising from the development of the laser system are presented.

Carbon dioxide laser laparoscopy performed with a flexible fiber in humans.

PubMed

Baggish, M S; Baltoyannis, P; Badawy, S; Laurey, D

1987-11-01

A flexible carbon dioxide laser fiber delivery system was used in conjunction with the laparoscope to treat 12 women. The 77 by 2 mm hollow fiber could subtend an arc of 90 degrees without significant loss of power or unfavorably affecting the delivery mode. As many as 20 W of power was transmitted through the fiber; however, carbon dioxide gas flow rates as high as 2000 cc/min reduced power by approximately 25%. Replaceable tips preserved fiber integrity to the extent that a single fiber could be reused repeatedly and gas sterilized without jeopardizing laser transmission. Of the 12 cases, endometriotic implants were vaporized in eight women, adhesiolysis was performed in four women, endometrial cysts were drained in two women, and vaporization of myomata was accomplished in two patients. The fiber was also used as a manipulating instrument and could be internally bent with a grasping forceps to better site the laser beam on a lesion. No complications related to the use of the carbon dioxide laser fiber were observed. The safety aspects of carbon dioxide laser fiber technology are not inconsiderable and could provide laser laparoscopy with an extra margin of security.

New approach of Co2 laser use in plastic and dermo-cosmetic surgery

NASA Astrophysics Data System (ADS)

Trelles, Mario A.; Trelles, O. R.; Romero, L. F.

1996-01-01

Laboratory and mathematical skin examination has played an important role in defining the clinical usefulness and limitations of laser, developing concepts and techniques that have further improved the effectiveness of laser treatment. In addition to this, new technological developments over the years, have helped define the specificity of laser-tissue interaction. Instantaneous conversion by thermal energy of water in a liquid state to a gaseous state when irradiation of skin is done by high power density carbon dioxide laser in short pulses, occurs so quickly that there is minimal thermal conduction to the adjacent tissues structures. The zone of thermal injury could be minimized to the order of only 50 micron thick. In spite of the limited effects of heat conduction, coagulation in vessels can be obtained as well, since small blood vessels are immediately sealed by the laser. Modern carbon dioxide systems can be programmed and make it possible to reproduce shots precisely to vaporize identically thin layers of soft tissue, since absorption by intracellular water limits the depth of penetration. Moreover, collimated handpieces make it possible to deliver a fixed beam diameter and a constant power density as the handpiece is steadily moved over lesions situated on uneven facial contours. The use of large spot sizes gives a more uniform vaporization thus damaging adjacent tissues to a lesser degree, but enlarging of the spot size requires higher energy levels per pulse so that the whole surface can reach a sufficiently high fluence for clean vaporization to take place. For this to be achieved, the fluence required is about 4 - 5 J/cm2 and so UltraPulseR carbon dioxide laser with a 3 mm spot size may be operated with optimal parameters for clean ablation. The resulting surface, covered by dry debris, can be removed by gently scrubbing to avoid thermal build-up, otherwise this remaining tissue can act as a refracting surface as the practical absence of water content means that the carbon dioxide laser light is not efficiently absorbed. This process is repeated layer-by-layer using the same laser parameters until all remaining abnormal tissue has been grossly removed. Utilized as a chain of rapid, short (approx. 1 ms) pulses, with high peak power, tissue can be effectively eliminated, taking advantage of the concept of the known thermal relaxation time of soft tissue. The current laser systems which are built according to the new concept of high technology based upon the knowledge of laser tissue interaction, known as UltraPulsedR Carbon Dioxide Laser, are capable of precise ablation and also of being used in cosmetically sensitive areas with minimal thermal damage. Although the precise clinical role for this laser has yet to be accurately defined, the potential benefits offered by its use appear to be substantial.

Laser-produced plasma EUV source using a colloidal microjet target containing tin dioxide nanoparticles

NASA Astrophysics Data System (ADS)

Higashiguchi, Takeshi; Dojyo, Naoto; Sasaki, Wataru; Kubodera, Shoichi

2006-10-01

We realized a low-debris laser-produced plasma extreme ultraviolet (EUV) source by use of a colloidal microjet target, which contained low-concentration (6 wt%) tin-dioxide nanoparticles. An Nd:YAG laser was used to produce a plasma at the intensity on the order of 10^11 W/cm^2. The use of low concentration nanoparticles in a microjet target with a diameter of 50 μm regulated the neutral debris emission from a target, which was monitored by a silicon witness plate placed 30 cm apart from the source in a vacuum chamber. No XPS signals of tin and/or oxygen atoms were observed on the plate after ten thousand laser exposures. The low concentration nature of the target was compensated and the conversion efficiency (CE) was improved by introducing double pulses of two Nd:YAG lasers operated at 532 and 1064 nm as a result of controlling the micro-plasma characteristics. The EUV CE reached its maximum of 1.2% at the delay time of approximately 100 ns with the main laser intensiy of 2 x10^11 W/cm^2. The CE value was comparable to that of a tin bulk target, which, however, produced a significant amount of neutral debris.

Airborne Carbon Dioxide Laser Absorption Spectrometer for IPDA Measurements of Tropospheric CO2: Recent Results

NASA Technical Reports Server (NTRS)

Spiers, Gary D.; Menzies, Robert T.

2008-01-01

The National Research Council's decadal survey on Earth Science and Applications from Space[1] recommended the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission for launch in 2013-2016 as a logical follow-on to the Orbiting Carbon Observatory (OCO) which is scheduled for launch in late 2008 [2]. The use of a laser absorption measurement technique provides the required ability to make day and night measurements of CO2 over all latitudes and seasons. As a demonstrator for an approach to meeting the instrument needs for the ASCENDS mission we have developed the airborne Carbon Dioxide Laser Absorption Spectrometer (CO2LAS) which uses the Integrated Path Differential Absorption (IPDA) Spectrometer [3] technique operating in the 2 micron wavelength region.. During 2006 a short engineering checkout flight of the CO2LAS was conducted and the results presented previously [4]. Several short flight campaigns were conducted during 2007 and we report results from these campaigns.

A Study on The Development of Local Exhaust Ventilation System (LEV’s) for Installation of Laser Cutting Machine

NASA Astrophysics Data System (ADS)

Harun, S. I.; Idris, S. R. A.; Tamar Jaya, N.

2017-09-01

Local exhaust ventilation (LEV) is an engineering system frequently used in the workplace to protect operators from hazardous substances. The objective of this project is design and fabricate the ventilation system as installation for chamber room of laser cutting machine and to stimulate the air flow inside chamber room of laser cutting machine with the ventilation system that designed. LEV’s fabricated with rated voltage D.C 10.8V and 1.5 ampere. Its capacity 600 ml, continuously use limit approximately 12-15 minute, overall length LEV’s fabricated is 966 mm with net weight 0.88 kg and maximum airflow is 1.3 meter cubic per minute. Stimulate the air flow inside chamber room of laser cutting machine with the ventilation system that designed and fabricated overall result get 2 main gas vapor which air and carbon dioxide. For air gas which experimented by using anemometer, general duct velocity that produce is same with other gas produce, carbon dioxide which 5 m/s until 10 m/s. Overall result for 5 m/s and 10 m/s as minimum and maximum duct velocity produce for both air and carbon dioxide. The air gas flow velocity that captured by LEV’s fabricated, 3.998 m/s average velocity captured from 5 m/s duct velocity which it efficiency of 79.960% and 7.667 m/s average velocity captured from 10 m/s duct velocity with efficiency of 76.665%. For carbon dioxide gas flow velocity that captured by LEV’s fabricated, 3.674 m/s average velocity captured from 5 m/s duct velocity which it efficiency of 73.480% and 8.255 m/s average velocity captured from 10 m/s duct velocity with efficiency of 82.545%.

Precision Column CO2 Measurement from Space Using Broad Band LIDAR

NASA Technical Reports Server (NTRS)

Heaps, William S.

2009-01-01

In order to better understand the budget of carbon dioxide in the Earth's atmosphere it is necessary to develop a global high precision understanding of the carbon dioxide column. To uncover the missing sink" that is responsible for the large discrepancies in the budget as we presently understand it, calculation has indicated that measurement accuracy of 1 ppm is necessary. Because typical column average CO2 has now reached 380 ppm this represents a precision on the order of 0.25% for these column measurements. No species has ever been measured from space at such a precision. In recognition of the importance of understanding the CO2 budget to evaluate its impact on global warming the National Research Council in its decadal survey report to NASA recommended planning for a laser based total CO2 mapping mission in the near future. The extreme measurement accuracy requirements on this mission places very strong constraints on the laser system used for the measurement. This work presents an overview of the characteristics necessary in a laser system used to make this measurement. Consideration is given to the temperature dependence, pressure broadening, and pressure shift of the CO2 lines themselves and how these impact the laser system characteristics. We are examining the possibility of making precise measurements of atmospheric carbon dioxide using a broad band source of radiation. This means that many of the difficulties in wavelength control can be treated in the detector portion of the system rather than the laser source. It also greatly reduces the number of individual lasers required to make a measurement. Simplifications such as these are extremely desirable for systems designed to operate from space.

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.

Current and emerging laser sensors for greenhouse gas sensing and leak detection

NASA Astrophysics Data System (ADS)

Frish, Michael B.

2014-05-01

To reduce atmospheric accumulation of the greenhouse gases methane and carbon dioxide, networks of continuously operating sensors that monitor and map their sources are desirable. In this paper, we discuss advances in laser-based open-path leak detectors, as well as technical and economic challenges inhibiting widespread sensor deployment for "ubiquitous monitoring". We describe permanently-installed, wireless, solar-powered sensors that overcome previous installation and maintenance difficulties while providing autonomous real-time leak reporting without false alarms.

High sensitivity detection of NO2 employing cavity ringdown spectroscopy and an external cavity continuously tunable quantum cascade laser.

PubMed

Rao, Gottipaty N; Karpf, Andreas

2010-09-10

A trace gas sensor for the detection of nitrogen dioxide based on cavity ringdown spectroscopy (CRDS) and a continuous wave external cavity tunable quantum cascade laser operating at room temperature has been designed, and its features and performance characteristics are reported. By measuring the ringdown times of the cavity at different concentrations of NO(2), we report a sensitivity of 1.2 ppb for the detection of NO(2) in Zero Air.

The Successful Treatment of Elephantiasis Nostras Verrucosa With Ablative Carbon Dioxide Laser.

PubMed

Robinson, Caitlin G; Lee, Kory R; Thomas, Valencia D

2018-03-01

Elephantiasis nostras verrucosa (ENV) is a disfiguring skin condition that is difficult to treat. Existing treatment modalities serve to improve cosmesis or treat symptoms. Herein, we report a case of ENV with lymphocutaneous fistula successfully treated with ablative carbon dioxide laser. A 57-year-old woman with biopsy-proven ENV with lymphocutaneous fistula was treated with ablative carbon dioxide laser to the symptomatic area of her right thigh in 3 treatment sessions over 6 months. The patient had resolution of lymphocutaneous drainage as well as 90% improvement in the appearance of ENV lesions at the 1-month follow-up visit. Ablative carbon dioxide laser may provide cosmetic, symptomatic, and medical benefit for patients with localized ENV.

Advancements for Active Remote Sensing of Carbon Dioxide from Space using the ASCENDS CarbonHawk Experiment Simulator: First Results

NASA Astrophysics Data System (ADS)

Obland, M. D.; Nehrir, A. R.; Lin, B.; Harrison, F. W.; Kooi, S. A.; Choi, Y.; Plant, J.; Yang, M. M.; Antill, C.; Campbell, J. F.; Ismail, S.; Browell, E. V.; Meadows, B.; Dobler, J. T.; Zaccheo, T. S.; Moore, B., III; Crowell, S.

2014-12-01

The ASCENDS CarbonHawk Experiment Simulator (ACES) is an Intensity-Modulated Continuous-Wave lidar system recently developed at NASA Langley Research Center that seeks to advance technologies and techniques critical to measuring atmospheric column carbon dioxide (CO2) mixing ratios in support of the NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission. These advancements include: (1) increasing the power-aperture product to approach ASCENDS mission requirements by implementing multi-aperture telescopes and multiple co-aligned laser transmitters; (2) incorporating high-efficiency, high-power Erbium-Doped Fiber Amplifiers (EDFAs); (3) developing and incorporating a high-bandwidth, low-noise HgCdTe detector and transimpedence amplifier (TIA) subsystem capable of long-duration operation on Global Hawk aircraft, and (4) advancing algorithms for cloud and aerosol discrimination. The ACES instrument architecture is being developed for operation on high-altitude aircraft and will be directly scalable to meet the ASCENDS mission requirements. ACES simultaneously transmits five laser beams: three from commercial EDFAs operating near 1571 nm, and two from the Exelis oxygen (O2) Raman fiber laser amplifier system operating near 1260 nm. The Integrated-Path Differential Absorption (IPDA) lidar approach is used at both wavelengths to independently measure the CO2 and O2 column number densities and retrieve the average column CO2 mixing ratio. The outgoing laser beams are aligned to the field of view of ACES' three fiber-coupled 17.8-cm diameter athermal telescopes. The backscattered light collected by the three telescopes is sent to the detector/TIA subsystem, which has a bandwidth of 4.7 MHz and operates service-free using a tactical dewar and cryocooler. Two key laser modulation approaches are being tested to significantly mitigate the effects of thin clouds on the retrieved CO2 column amounts. Full instrument development concluded in the spring of 2014. After ground range tests of the instrument, ACES successfully completed six test flights on the Langley Hu-25 aircraft in July, 2014, and recorded data at multiple altitudes over land and ocean surfaces with and without intervening clouds. Preliminary results from these flights will be presented in this paper.

Real-time diagnostics of a jet engine exhaust using an intra-pulse quantum cascade laser spectrometer

NASA Astrophysics Data System (ADS)

Duxbury, Geoffrey; Hay, Kenneth G.; Langford, Nigel; Johnson, Mark P.; Black, John D.

2011-09-01

It has been demonstrated that an intra-pulse scanned quantum cascade laser spectrometer may be used to obtain real-time diagnostics of the amounts of carbon monoxide, carbon dioxide, and water, in the exhaust of an aero gas turbine (turbojet) engine operated in a sea level test cell. Measurements have been made of the rapid changes in composition following ignition, the composition under steady state operating conditions, and the composition changes across the exhaust plume. The minimum detection limit for CO in a double pass through a typical gas turbine plume of 50 cm in diameter, with 0.4 seconds integration time, is approximately 2 ppm.

Selective Removal of Residual Orthodontic Composite Using a Rapidly Scanned Carbon Dioxide Laser with Spectral Feedback

NASA Astrophysics Data System (ADS)

Hirasuna, Krista

Background and Objective: Excessive heat accumulation within the tooth, incomplete removal of composite, and variable damage to the enamel are shortcomings of using conventional burs to remove residual orthodontic composite after debonding fixed appliances. The objective of this study was to determine if composite could be selectively removed from the enamel surface using a rapidly scanned carbon dioxide laser controlled by spectral feedback. Materials and Methods: A carbon dioxide laser operating at a wavelength of 9.3 microm with a pulse duration of 10-15 micros and a pulse repetition rate of ˜ 200 Hz was used to selectively remove composite from the buccal surfaces of 21 extracted teeth. GrenGloo(TM) composite was used to better visualize residual composite and the amount of enamel lost was measured with optical microscopy. A spectral feedback system utilizing a miniature spectrometer was used to control the laser scanning system. Pulpal temperature measurements were performed during composite removal to determine if there was excessive heat accumulation. Results: The amount of enamel lost averaged 22.7microm +/- 8.9 and 25.3 microm +/- 9.4 for removal at 3.8 and 4.2 J/cm2, respectively. An average maximum temperature rise of 1.9°C +/- 1.5 was recorded, with no teeth approaching the critical value of 5.5°C. The average time of composite removal was 19.3 +/- 4.1 seconds. Conclusions: Residual orthodontic composite can be rapidly removed from the tooth surface using a rapidly scanned CO2 laser with spectral feedback, with minimal temperature rise within the pulp and with minimal damage to the underlying enamel surface.

A Carbon Dioxide Laser Bibliography, 1964-1969,

DTIC Science & Technology

A bibliography concerning carbon dioxide lasers has been compiled covering the period 1964 through 1969. The chronologically listed references have also been catalogued into an author index and a subject index. (Author)

A new sealed RF-excited CO2 laser for enamel ablation operating at 9.4-μm with a pulse duration of 26-μs

PubMed Central

Chan, Kenneth H.; Jew, Jamison M.; Fried, Daniel

2016-01-01

Several studies over the past 20 years have shown that carbon dioxide lasers operating at wavelengths between 9.3 and 9.6-μm with pulse durations near 20-μs are ideal for hard tissue ablation. Those wavelengths are coincident with the peak absorption of the mineral phase. The pulse duration is close to the thermal relaxation time of the deposited energy of a few microseconds which is short enough to minimize peripheral thermal damage and long enough to minimize plasma shielding effects to allow efficient ablation at practical rates. The desired pulse duration near 20-μs has been difficult to achieve since it is too long for transverse excited atmospheric pressure (TEA) lasers and too short for radio-frequency (RF) excited lasers for efficient operation. Recently, Coherent Inc. (Santa Clara, CA) developed the Diamond J5-V laser for microvia drilling which can produce laser pulses greater than 100-mJ in energy at 9.4-μm with a pulse duration of 26-μs and it can achieve pulse repetition rates of 3 KHz. We report the first results using this laser to ablate dental enamel. Efficient ablation of dental enamel is possible at rates exceeding 50-μm per pulse. This laser is ideally suited for the selective ablation of carious lesions. PMID:27006521

Optoacoustic Determination of Carbon Dioxide Concentration in Exhaled Breath in Various Human Diseases*

NASA Astrophysics Data System (ADS)

Ageev, V. G.; Nikiforova, O. Yu.

2016-11-01

We determined the carbon dioxide concentrations in exhaled breath from healthy donors and patients with various diseases from the absorption spectra of test samples, recorded on a laser optoacoustic gas analyzer based on a CO2 laser. We observed that the carbon dioxide concentrations in exhaled breath from healthy donors is higher than in patients with various diseases.

Carbon dioxide (CO2) laser treatment of cutaneous papillomas in a common snapping turtle, Chelydra serpentina.

PubMed

Raiti, Paul

2008-06-01

Carbon dioxide (CO2) laser was used to treat multiple cutaneous papillomas on an adult female common snapping turtle, Chelydra serpentina serpentina. A combination of excisional and ablative techniques provided excellent intraoperative visibility and postoperative results due to the laser's unique ability to incise and vaporize soft tissue.

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.

The new method of real-time detection of 129I2, 129I127I, 127I2 and NO2 in gases using tunable diode laser operating in the range of 632-637 nm

NASA Astrophysics Data System (ADS)

Kireev, S. V.; Shnyrev, S. L.

2018-02-01

This paper develops the new selective real-time method of 129I2, 129I127I, 127I2 and NO2 detection in gases. Measuring concentrations of molecular iodine is based on fluorescence exciting by the radiation of a tunable diode laser, operating in the red spectral region (632-637 nm), at two or three wavelengths corresponding to the centers of the absorption lines of 129I2, 129I127I and 127I2. Detection of NO2 is performed by measuring the intensity of the tunable diode laser radiation, which passed through the measuring cell. Measured simultaneously, boundary ratios of iodine molecule concentrations measured simultaneously are about 10-6. The sensitivity of nitrogen dioxide detection is 1016 cm-3.

Selected developments in laser wire stripping. [cutting insulation from aerospace-type wires and cables

NASA Technical Reports Server (NTRS)

1977-01-01

The operation of mechanical and thermal strippers and the early development of laser wire strippers are reviewed. NASA sponsored development of laser wire stripping for space shuttle includes bench-type strippers as well as an advanced portable hand-held stripper which incorporates a miniaturized carbon dioxide laser and a rotating optics unit with a gas-jet assist and debris exhaust. Drives and controls girdle the wire and slit the remaining slug without manual assistance. This unit can strip wire sizes 26 through 12 gage. A larger-capacity hand-held unit for wire sizes through 1/0 gage was built using a neodynium-doped yttrium aluminum garnet (Nd:YAG) laser. The hand-held units have a flexible umbilical cable to an accompanying cart that carries the power supply, gas supply, cooling unit, and the controls.

Tuneable diode laser gas analyser for methane measurements on a large scale solid oxide fuel cell

NASA Astrophysics Data System (ADS)

Lengden, Michael; Cunningham, Robert; Johnstone, Walter

2011-10-01

A new in-line, real time gas analyser is described that uses tuneable diode laser spectroscopy (TDLS) for the measurement of methane in solid oxide fuel cells. The sensor has been tested on an operating solid oxide fuel cell (SOFC) in order to prove the fast response and accuracy of the technology as compared to a gas chromatograph. The advantages of using a TDLS system for process control in a large-scale, distributed power SOFC unit are described. In future work, the addition of new laser sources and wavelength modulation will allow the simultaneous measurement of methane, water vapour, carbon-dioxide and carbon-monoxide concentrations.

The principle of a three-staged operation in the surgery of acne scars.

PubMed

Whang, K K; Lee, M

1999-01-01

Acne scars cannot be effectively corrected by a single treatment modality because of their widely varied depth and width. We assessed the effectiveness of staged combinations of several surgical modalities in the treatment of acne scars. Focal chemical peeling, carbon dioxide (CO2) laser, scar excision, punch grafting, and dermabrasion were used. Initially, focal chemical peeling was performed on all patients and then CO2 laser, scar excision, and punch grafts were used for deep scars. Finally, dermabrasion was done for the remaining scars. Seventy-five percent of patients showed excellent or good results. The degree of improvement increased as the follow-up periods and number of focal chemical peeling procedures increased and as the 3-staged operation progressed. A 3-staged operation is effective in the treatment of patients with various types of acne scars.

Efficacy of autologous platelet-rich plasma combined with fractional ablative carbon dioxide resurfacing laser in treatment of facial atrophic acne scars: A split-face randomized clinical trial.

PubMed

Faghihi, Gita; Keyvan, Shima; Asilian, Ali; Nouraei, Saeid; Behfar, Shadi; Nilforoushzadeh, Mohamad Ali

2016-01-01

Autologous platelet-rich plasma has recently attracted significant attention throughout the medical field for its wound-healing ability. This study was conducted to investigate the potential of platelet-rich plasma combined with fractional laser therapy in the treatment of acne scarring. Sixteen patients (12 women and 4 men) who underwent split-face therapy were analyzed in this study. They received ablative fractional carbon dioxide laser combined with intradermal platelet-rich plasma treatment on one half of their face and ablative fractional carbon dioxide laser with intradermal normal saline on the other half. The injections were administered immediately after laser therapy. The treatment sessions were repeated after an interval of one month. The clinical response was assessed based on patient satisfaction and the objective evaluation of serial photographs by two blinded dermatologists at baseline, 1 month after the first treatment session and 4 months after the second. The adverse effects including erythema and edema were scored by participants on days 0, 2, 4, 6, 8, 15 and 30 after each session. Overall clinical improvement of acne scars was higher on the platelet-rich plasma-fractional carbon dioxide laser treated side but the difference was not statistically significant either 1 month after the first treatment session (P = 0.15) or 4 months after the second (P = 0.23). In addition, adverse effects (erythema and edema) on the platelet-rich plasma-fractional carbon dioxide laser-treated side were more severe and of longer duration. Small sample size, absence of all skin phototypes within the study group and lack of objective methods for the evaluation of response to treatment and adverse effects were the limitations. This study demonstrated that adding platelet-rich plasma to fractional carbon dioxide laser treatment did not produce any statistically significant synergistic effects and also resulted in more severe side effects and longer downtime.

Laser Doppler technology applied to atmospheric environmental operating problems

NASA Technical Reports Server (NTRS)

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

1976-01-01

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

A compact tunable diode laser absorption spectrometer to monitor CO2 at 2.7 μm wavelength in hypersonic flows.

PubMed

Vallon, Raphäel; Soutadé, Jacques; Vérant, Jean-Luc; Meyers, Jason; Paris, Sébastien; Mohamed, Ajmal

2010-01-01

Since the beginning of the Mars planet exploration, the characterization of carbon dioxide hypersonic flows to simulate a spaceship's Mars atmosphere entry conditions has been an important issue. We have developed a Tunable Diode Laser Absorption Spectrometer with a new room-temperature operating antimony-based distributed feedback laser (DFB) diode laser to characterize the velocity, the temperature and the density of such flows. This instrument has been tested during two measurement campaigns in a free piston tunnel cold hypersonic facility and in a high enthalpy arc jet wind tunnel. These tests also demonstrate the feasibility of mid-infrared fiber optics coupling of the spectrometer to a wind tunnel for integrated or local flow characterization with an optical probe placed in the flow.

New CO2 laser waveguide systems: advances in surgery of tracheal stenosis

NASA Astrophysics Data System (ADS)

Stasche, Norbert; Bernecker, Frank; Hoermann, Karl

1996-01-01

The carbon dioxide laser is a well established tool in the surgical treatment of laryngeal and tracheal stenosis. Usually the laser beam is applied by a microscope/micromanipulator device. Different types of rigid laryngoscopes and bronchoscopes provide access to nearly every area of larynx, trachea and main bronchi. In order to be treated with this equipment the target tissue has to be in a straight optical axis with the laser beam output at the micromanipulator. We report about one patient who presented with severe dyspnea due to granulation tissue directly below his left vocal cord. He was suffering from tracheomalacia for several years and was successfully treated by tracheostomy and a Montgomery's silicone T-tube as a stent. Then granulation tissue blocked the upper orifice of the Montgomery's T-tube. First removal by a carbon dioxide laser beam through the laryngoscope would have required sacrificing his intact left vocal cord. We removed the obstructing tissue by using the ArthroLaseTM System: the carbon dioxide laser beam was conducted through a 90 degree bent rigid probe, using the tracheostomy as an access. This ArthroLaseTM System was originally designed for arthroscopic surgery. In this special case however it successfully extends the use of the carbon dioxide laser in otolaryngology.

Superpulsed carbon dioxide laser: an update on cutaneous surgical applications

NASA Astrophysics Data System (ADS)

Wheeland, Ronald G.

1990-06-01

Superpulsing the carbon dioxide laser allows delivery of high energy pulses separated by short pauses during which tissue cooling can occur.1 This new technology can provide several important advantages in cutaneous surgery over similar procedures performed with conventional continuous discharge carbon dioxide laser systems. In the excisional mode, there is a two-thirds reduction in thermal necrosis of the wound edge.2 This should translate into more rapid healing3 and increased rate of gain in tensile strength. In the vaporizational mode, precise, superficial and bloodless ablation of multiple benign appendigeal tumors is possible with less thermal damage yielding excellent cosmetic results. The establishment through additional research of accurate laser parameters, pulse duration, peak energy levels, and frequency of pulses, will help improve the specificity of the laser-tissue interaction to provide even better surgical results.

Carbon Dioxide Laser Fiber Optics In Endoscopy

NASA Astrophysics Data System (ADS)

Fuller, Terry A.

1982-12-01

Carbon dioxide laser surgery has been limited to a great extent to surgical application on the integument and accessible cavities such as the cervix, vagina, oral cavities, etc. This limitation has been due to the rigid delivery systems available to all carbon dioxide lasers. Articulating arms (series of hollow tubes connected by articulating mirrors) have provided an effective means of delivery of laser energy to the patient as long as the lesion was within the direct line of sight. Even direct line-of-sight applications were restricted to physical dimension of the articulating arm or associated hand probes, manipulators and hollow tubes. The many attempts at providing straight endoscopic systems to the laser only stressed the need for a fiber optic capable of carrying the carbon dioxide laser wavelength. Rectangular and circular hollow metal waveguides, hollow dielectric waveguides have proven ineffective to the stringent requirements of a flexible surgical delivery system. One large diameter (1 cm) fiber optic delivery system, incorporates a toxic thalliumAbased fiber optic material. The device is an effective alternative to an articulating arm for external or conventional laser surgery, but is too large and stiff to use as a flexible endoscopic tool. The author describes the first highly flexible inexpensive series of fiber optic systems suitable for either conventional or endoscopic carbon dioxide laser surgery. One system (IRFLEX 3) has been manufactured by Medlase, Inc. for surgical uses capable of delivering 2000w, 100 mJ pulsed energy and 15w continuous wave. The system diameter is 0.035 inches in diameter. Surgically suitable fibers as small as 120 um have been manufactured. Other fibers (IRFLEX 142,447) have a variety of transmission characteristics, bend radii, etc.

Performance of 100-W HVM LPP-EUV source

NASA Astrophysics Data System (ADS)

Mizoguchi, Hakaru; Nakarai, Hiroaki; Abe, Tamotsu; Nowak, Krzysztof M.; Kawasuji, Yasufumi; Tanaka, Hiroshi; Watanabe, Yukio; Hori, Tsukasa; Kodama, Takeshi; Shiraishi, Yutaka; Yanagida, Tatsuya; Soumagne, Georg; Yamada, Tsuyoshi; Yamazaki, Taku; Okazaki, Shinji; Saitou, Takashi

2015-08-01

At Gigaphoton Inc., we have developed unique and original technologies for a carbon dioxide laser-produced tin plasma extreme ultraviolet (CO2-Sn-LPP EUV) light source, which is the most promising solution for high-power high-volume manufacturing (HVM) EUV lithography at 13.5 nm. Our unique technologies include the combination of a pulsed CO2 laser with Sn droplets, the application of dual-wavelength laser pulses for Sn droplet conditioning, and subsequent EUV generation and magnetic field mitigation. Theoretical and experimental data have clearly shown the advantage of our proposed strategy. Currently, we are developing the first HVM light source, `GL200E'. This HVM light source will provide 250-W EUV power based on a 20-kW level pulsed CO2 laser. The preparation of a high average-power CO2 laser (more than 20 kW output power) has been completed in cooperation with Mitsubishi Electric Corporation. Recently, we achieved 140 W at 50 kHz and 50% duty cycle operation as well as 2 h of operation at 100 W of power level. Further improvements are ongoing. We will report the latest status and the challenge to reach stable system operation of more than 100 W at about 4% conversion efficiency with 20-μm droplets and magnetic mitigation.

Quantitative evaluation of the safety of mucosal incision and submucosal dissection for colon during endoscopic submucosal dissection using carbon dioxide laser

NASA Astrophysics Data System (ADS)

Noguchi, Takuma; Honda, Norihiro; Hazama, Hisanao; Morita, Yoshinori; Awazu, Kunio

2018-02-01

Since the increase in the overall mortality rate in patients with colon cancer is remarkably high in recent years, early treatment is required. For this reason, endoscopic submucosal dissection (ESD) has been at the forefront of international attention as a low invasive treatment for early digestive cancer. In current ESD procedure, an electrosurgical knife is used for mucosal incision and subsequent submucosal dissection. However, the perforation has been reported to occur by approximately 5%. Thus, to enhance the tissue selectivity of this modality, we focused on the application of laser for ESD. A carbon dioxide laser was chosen as a surgical knife because the saline or a sodium hyaluronate solution injected into the submucosal layer in current ESD procedure has a high absorption coefficient at the wavelength of the carbon dioxide laser. In this research, ex vivo experiment was performed at the output power of 3-7 W and discuss the optimum irradiation power of laser. As a result of ex vivo experiment using extracted porcine colon tissues, mucosal incision and submucosal dissection were safely and less invasively performed in every output power, without reaching the thermal damage to a muscular layer. This is because a carbon dioxide laser is strongly absorbed by saline injected into submucosa. ESD using a carbon dioxide laser is a safer method for the treatment of early colon cancer. We are planning to measure and compare the optical and thermal properties of porcine colon with those of human colon.

Laser endoscopy.

PubMed

McElvein, R B

1981-11-01

A carbon dioxide laser operating in the invisible infrared range (10.6 mu) generates a beam of energy that is almost completely absorbed by biological tissue with release of intense heat and rapid destruction. A laser attached to a rigid bronchoscope has been used in 18 patients ranging in age from 21 to 62 years to treat a variety of causes of airway obstruction. These include tracheal stenosis and granulation tissue (6 patients), adenoma (1), web (2), and carcinoma (9). The results were good in 15 and poor in 3 patients. However, all patients had an improved airway after laser treatment with the best results occurring in patients with benign, inflammatory disease. The advantages of the laser are a lack of bleeding, minimal edema after treatment, and minimal scar formation. The disadvantages are the expense of the machine, and the need for general anesthesia and direct visualization of the lesion.

Ablative Fractional Carbon Dioxide Laser in the Treatment of Chronic, Posttraumatic, Lower-Extremity Ulcers in Elderly Patients.

PubMed

Phillips, Tania J; Morton, Laurel M; Uebelhoer, Nathan S; Dover, Jeffrey S

2015-08-01

Treating posttraumatic lower extremity wounds can be challenging, especially in elderly patients. Recently, the use of fractional carbon dioxide laser has been shown to improve wound healing in scar-related wounds. We used this treatment modality in posttraumatic wounds that were slow to heal in 3 elderly patients. Each wound underwent one fractional carbon dioxide laser treatment. The wound base was treated at 30 mJ and 5% density. The entire wound edge and 1 to 2 cm into the normal surrounding skin were treated at 50 mJ and 5% density. One pass was completed at 150 Hz per treatment. Treatments were well tolerated with only mild discomfort. Each wound healed by 60% or greater within 3 weeks. No adverse events were reported aside from mild and transient erythema at site of treatment. Fractional carbon dioxide laser treatment appeared to accelerate healing in each of these posttraumatic wounds. It may be a helpful adjunct in nonhealing posttraumatic wounds.

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.

Phase-selective vanadium dioxide (VO2) nanostructured thin films by pulsed laser deposition

NASA Astrophysics Data System (ADS)

Masina, B. N.; Lafane, S.; Wu, L.; Akande, A. A.; Mwakikunga, B.; Abdelli-Messaci, S.; Kerdja, T.; Forbes, A.

2015-10-01

Thin films of monoclinic nanostructured vanadium dioxide are notoriously difficult to produce in a selective manner. To date, post-annealing, after pulsed laser deposition (PLD), has been used to revert the crystal phase or to remove impurities, and non-glass substrates have been employed, thus reducing the efficacy of the transparency switching. Here, we overcome these limitations in PLD by optimizing a laser-ablation and deposition process through optical imaging of the laser-induced plasma. We report high quality monoclinic rutile-type vanadium dioxide (VO2) (M1) nanoparticles without post-annealing, and on a glass substrate. Our samples demonstrate a reversible metal-to-insulator transition at ˜43 °C, without any doping, paving the way to switchable transparency in optical materials at room temperature.

Discovery of natural gain amplification in the 10-micrometer carbon dioxide laser bands on Mars - A natural laser

NASA Technical Reports Server (NTRS)

Mumma, M. J.; Buhl, D.; Chin, G.; Deming, D.; Espenak, F.; Kostiuk, T.; Zipoy, D.

1981-01-01

Fully resolved intensity profiles of various lines in the carbon dioxide band at 10.4 micrometers have been measured on Mars with an infrared heterodyne spectrometer. Analysis of the line shapes shows that the Mars atmosphere exhibits positive gain in these lines. The detection of natural optical gain amplification enables identification of these lines as a definite natural laser.

Evaluation of an airborne triple-pulsed 2 μm IPDA lidar for simultaneous and independent atmospheric water vapor and carbon dioxide measurements.

PubMed

Refaat, Tamer F; Singh, Upendra N; Yu, Jirong; Petros, Mulugeta; Ismail, Syed; Kavaya, Michael J; Davis, Kenneth J

2015-02-20

Water vapor and carbon dioxide are the most dominant greenhouse gases directly contributing to the Earth's radiation budget and global warming. A performance evaluation of an airborne triple-pulsed integrated path differential absorption (IPDA) lidar system for simultaneous and independent monitoring of atmospheric water vapor and carbon dioxide column amounts is presented. This system leverages a state-of-the-art Ho:Tm:YLF triple-pulse laser transmitter operating at 2.05 μm wavelength. The transmitter provides wavelength tuning and locking capabilities for each pulse. The IPDA lidar system leverages a low risk and technologically mature receiver system based on InGaAs pin detectors. Measurement methodology and wavelength setting are discussed. The IPDA lidar return signals and error budget are analyzed for airborne operation on-board the NASA B-200. Results indicate that the IPDA lidar system is capable of measuring water vapor and carbon dioxide differential optical depth with 0.5% and 0.2% accuracy, respectively, from an altitude of 8 km to the surface and with 10 s averaging. Provided availability of meteorological data, in terms of temperature, pressure, and relative humidity vertical profiles, the differential optical depth conversion into weighted-average column dry-air volume-mixing ratio is also presented.

Carbon dioxide laser for de-epithelialization of periodontal flaps.

PubMed

Centty, I G; Blank, L W; Levy, B A; Romberg, E; Barnes, D M

1997-08-01

Regeneration of mineralized and soft connective tissue components of the attachment apparatus is the main goal in the treatment of periodontal diseases. Often, apical migration of epithelium (long junctional epithelium) effectively prevents the formation of bone and connective tissue attachment after periodontal surgery. The purpose of the present study was to compare conventional periodontal surgery combined with carbon dioxide laser and conventional periodontal surgery alone with respect to epithelial elimination and degree of necrosis of mucoperiosteal flaps. After signing a consent form, five patients with at least two comparable bilateral periodontal defects needing pocket elimination surgery participated in this study. The investigators randomly divided each side into test and control sites. Each patient received oral hygiene instruction and initial therapy prior to surgery. At surgery, the test site received a sulcular incision and carbon dioxide laser de-epithelialization of the outer and inner aspects of the flap. The control group received reverse bevel incision only. The surgeon performed open flap debridement on all teeth. At the time of surgery, the surgeon did a biopsy of each site and submitted specimens for histologic evaluation. A matched pairs t-test was used to analyze the data. The results show significant differences between the carbon dioxide laser and reverse bevel incision with respect to sulcular (P < or = 0.025) and gingival (external) (P < or = 0.01) flap surface epithelial elimination and tissue necrosis (P < or = 0.005). These results should be replicated with a larger number of subjects. The carbon dioxide laser eliminated sulcular and gingival (external) epithelium without disturbing underlying connective tissue. This finding supports the concept that the carbon dioxide wavelength has little or no effect on tissues beyond the target. However, neither laser nor blade eliminated all the epithelium. Researchers observed chronic inflammation in the control and test sites, with a predominance of plasma cells. Lining the sulcular and gingival (external) lased areas, investigators found coagulation necrosis covered by fibrin and coagulated blood. The laser appears to effectively remove epithelium at the time of surgery; however, future long-term, well-controlled quantitative histologic studies are needed to evaluate the effect of repeated carbon dioxide laser de-epithelialization of the gingival (external) surface of mucoperiosteal flaps at intervals during the healing period.

A Compact Tunable Diode Laser Absorption Spectrometer to Monitor CO2 at 2.7 μm Wavelength in Hypersonic Flows

PubMed Central

Vallon, Raphäel; Soutadé, Jacques; Vérant, Jean-Luc; Meyers, Jason; Paris, Sébastien; Mohamed, Ajmal

2010-01-01

Since the beginning of the Mars planet exploration, the characterization of carbon dioxide hypersonic flows to simulate a spaceship’s Mars atmosphere entry conditions has been an important issue. We have developed a Tunable Diode Laser Absorption Spectrometer with a new room-temperature operating antimony-based distributed feedback laser (DFB) diode laser to characterize the velocity, the temperature and the density of such flows. This instrument has been tested during two measurement campaigns in a free piston tunnel cold hypersonic facility and in a high enthalpy arc jet wind tunnel. These tests also demonstrate the feasibility of mid-infrared fiber optics coupling of the spectrometer to a wind tunnel for integrated or local flow characterization with an optical probe placed in the flow. PMID:22219703

An audit of the use of the CO2 laser in oral and maxillofacial surgery

NASA Astrophysics Data System (ADS)

Pinheiro, Antonio L. B.; Santos de Almeida, Darcy

2004-09-01

The use of the Carbon dioxide Laser to perform surgical procedures in the oral cavity has been described as a successful method for the treatment of several conditions affecting the maxillofacial region. Several benefits of the use of the CO2 Laser have been reported and includes reduction of postoperative pain and edema, local hemosthasis, reduction of scaring and wound contraction and infection. The aim of this work is to present our clinical experience in performing several surgical procedures using the CO2 Laser to treat soft tissue pathologies of both benign and malign origin as well as on performing pre-prosthetic surgery, apical surgery and on the treatment of pre-malignancies. Our experience demonstrate that the use of the Carbon dioxide Laser in treating oral soft-tissue pathology presents advantages over conventional techniques and local discomfort and pain are the most common complaints after Laser surgery. The Carbon dioxide Laser does not offer any enhanced cure-rate for oral pathology, but rather it is a precise means of removing soft tissue lesions with little upset afterwards.

Flammability of topical preparations and surgical dressings in cutaneous and laser surgery: a controlled simulation study.

PubMed

Arefiev, Katharine; Warycha, Melanie; Whiting, Dennis; Alam, Murad

2012-10-01

Surgical fires are a rare, but serious complication of dermatologic procedures involving electrosurgical and laser devices. Given the lack of data regarding basic fire safety principles, many dermatologists remain unaware of this potential risk. We evaluated the flammability of topical preparations and surgical drapes commonly encountered in the immediate operative field during cutaneous and laser surgery. Surgical dressings, drapes, and pork belly skin were examined for fire risk upon exposure to isopropyl alcohol, chlorhexidine gluconate, and aluminum chloride under dry, saturated, and damp conditions. Both electrosurgery and a carbon-dioxide laser were used as ignition sources. At least some char was observed in 86 of 126 simulated conditions (68%). Flames occurred in 2 test conditions: dry underpad drapes and cotton balls exposed to the carbon-dioxide laser. In general, drapes and dressings dampened or saturated with isopropyl alcohol failed to ignite with electrofulguration or electrodessication, although sparks and moderate char developed on pork belly skin and the underpad drape. Materials dampened or saturated with chlorhexidine gluconate, which contains isopropyl alcohol, generated less smoke and char compared with materials exposed to aluminum chloride, which does not contain alcohol. Future studies may assess the flammability of materials in the setting of oxygen supplementation. In common cutaneous surgical environments, electrosurgery or ablative laser may lead to char and rarely to fire. Char may be seen in up to two thirds of simulated conditions, and in a minute proportion of conditions, fire is observed. Copyright © 2012 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.

Infrared Lasers in Chemistry.

ERIC Educational Resources Information Center

John, Phillip

1982-01-01

Selected infrared laser chemistry topics are discussed including carbon dioxide lasers, infrared quanta and molecules, laser-induced chemistry, structural isomerization (laser purification, sensitized reactions, and dielectric breakdown), and fundamental principles of laser isotope separation, focusing on uranium isotope separation. (JN)

Ocular Absorption of Laser Radiation for Calculating Personnel Hazards

DTIC Science & Technology

1974-11-30

radia- tion incident on the cell in the conventional spectrophotometers. Carbon Dioxide Laser Measurements: We were interested in obtaining some total...Measurements 19Carbon Dioxide Laser Measurements 20T REFERENCES 22 APPENDIX 1: Fluorescence of Ocular Media 43SAPPENDIX I1: Absorption of Water and...result that we can not get mean- ingful data when the absorption coefficient approaches 10 . In order to work in these more abosrbing regions, we must

Low-debris, efficient laser-produced plasma extreme ultraviolet source by use of a regenerative liquid microjet target containing tin dioxide (SnO2) nanoparticles

NASA Astrophysics Data System (ADS)

Higashiguchi, Takeshi; Dojyo, Naoto; Hamada, Masaya; Sasaki, Wataru; Kubodera, Shoichi

2006-05-01

We demonstrated a low-debris, efficient laser-produced plasma extreme ultraviolet (EUV) source by use of a regenerative liquid microjet target containing tin-dioxide (SnO2) nanoparticles. By using a low SnO2 concentration (6%) solution and dual laser pulses for the plasma control, we observed the EUV conversion efficiency of 1.2% with undetectable debris.

Measurement of Trace Water Vapor in a Carbon Dioxide Removal Assembly Product Stream

NASA Technical Reports Server (NTRS)

Wormhoudt, Joda; Shorter, Joanne H.; McManus, J. Barry; Nelson, David D.; Zahniser, Mark S.; Freedman, Andrew; Campbell, Melissa; Chang, Clarence T.; Smith, Frederick D.

2004-01-01

The International Space Station Carbon Dioxide Removal Assembly (CDRA) uses regenerable adsorption technology to remove carbon dioxide (COP) from cabin air. Product water vapor measurements from a CDRA test bed at the NASA Marshall Space Flight Center were made using a tunable infrared diode laser differential absorption spectrometer (TILDAS) provided by NASA Glenn Research Center. The TILDAS instrument exceeded all the test specifications, including sensitivity, dynamic range, time response, and unattended operation. During the COP desorption phase, water vapor concentrations as low as 5 ppmv were observed near the peak of CO2 evolution, rising to levels of approx. 40 ppmv at the end of a cycle. Periods of high water concentration (>100 ppmv) were detected and shown to be caused by an experimental artifact. Measured values of total water vapor evolved during a single desorption cycle were as low as 1 mg.

Comparison of Efficacy of Carbon Dioxide (CO2) Laser with Cutting Diathermy in Surgical Excision of Early Carcinoma Tongue.

PubMed

Rashid, Muhammad; Hashmi, Muhammad Ali; Maqbool, Shahzad; Dastigir, Majid

2015-10-01

To compare the efficacy of carbon dioxide (CO(2)) laser with cutting diathermy as a cutting device in surgical excision of early carcinoma tongue. Experimental study. Combined Military Hospital (CMH), Rawalpindi and CMH, Lahore, from July 2008 to July 2011. Twenty two biopsy proven cases of T(1) and early T(2) squamous cell carcinoma of tongue were divided in two equal groups of 11 each labeled as A and B. Tumor was excised by CO(2) laser in group A while cutting diathermy was done in group B. For both groups tumor excision time, per-operative blood loss, postoperative oral swelling and pain was recorded. Excision time of tumor was assessed in minutes and amount of blood loss in milliliters till complete hemostasis after removal of primary tumor. Postoperatively patients were assessed on 12 hourly basis for 48 hours for pain. Pain was analyzed on visual analogue score 1 - 10. Oral swelling was assessed once after 24 hours and labeled as mild, moderate and severe. Independent sample t-test was applied for analysis of excision time, postoperative pain and per-operative blood loss for both groups. Postoperative swelling was analyzed using Fisher's exact test. P-value of < 0.05 was considered significant. The mean age at diagnosis in group A was 49.36 ± 5.27 years, while in group B patients had mean age of 50.73 ± 8.13 years. In group A, 4/11 (36.3%) patients were having tumor stage T(1) while 7/11 (63.6%) had T(2) stage tumor. In group B, 5/11 (45.4%) were having T1 and 6/11 (54.5%) were having stage T(2) tumor. Excision time was significantly shorter for group B (p=0.003), but group A had less postoperative pain (p=0.001), less per-operative blood loss (p=0.001) and less postoperative oral swelling (p=0.021). Early carcinoma tongue is better removed by laser than electrocautery in terms of postoperative morbidity, per-operative blood loss, postoperative pain and oral swelling.

Carbon dioxide laser microsurgery of the uterine tube.

PubMed

Baggish, M S; Chong, A P

1981-07-01

The carbon dioxide (CO2) laser was used to perform microsurgical excision of obstructed tubal segments in rabbit and human subjects. Approximation of the freshly severed tubes by means of laser "welding" was evaluated in both groups investigated. More important, the laser beam cuts accurately and atraumatically while sealing small vascular channels. Scanning electron microscopic studies of the human fallopian tube following laser surgery were done to determine the extent of tissue injury. At a distance of 1 mm distal to the vaporization and necrotic impact zone, normal tubal anatomy was observed. Follow-up data are presented for 7 women who underwent laser beam tuboplasty between 1979 and 1980. The principle advantages of the CO2 laser are its precise control, minimal tissue injury, and hemostatic properties.

Phase-selective vanadium dioxide (VO{sub 2}) nanostructured thin films by pulsed laser deposition

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

Masina, B. N., E-mail: BMasina@csir.co.za, E-mail: slafane@cdta.dz; School of Physics, University of KwaZulu-Natal, Private Bag X54001, Durban 4000; Lafane, S., E-mail: BMasina@csir.co.za, E-mail: slafane@cdta.dz

2015-10-28

Thin films of monoclinic nanostructured vanadium dioxide are notoriously difficult to produce in a selective manner. To date, post-annealing, after pulsed laser deposition (PLD), has been used to revert the crystal phase or to remove impurities, and non-glass substrates have been employed, thus reducing the efficacy of the transparency switching. Here, we overcome these limitations in PLD by optimizing a laser-ablation and deposition process through optical imaging of the laser-induced plasma. We report high quality monoclinic rutile-type vanadium dioxide (VO{sub 2}) (M1) nanoparticles without post-annealing, and on a glass substrate. Our samples demonstrate a reversible metal-to-insulator transition at ∼43 °C, withoutmore » any doping, paving the way to switchable transparency in optical materials at room temperature.« less

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.

Facilities to Support Beamed Energy Launch Testing at the Laser Hardened Materials Evaluation Laboratory (LHMEL)

NASA Astrophysics Data System (ADS)

Lander, Michael L.

2003-05-01

The Laser Hardened Materials Evaluation Laboratory (LHMEL) has been characterizing material responses to laser energy in support of national defense programs and the aerospace industry for the past 26 years. This paper reviews the overall resources available at LHMEL to support fundamental materials testing relating to impulse coupling measurement and to explore beamed energy launch concepts. Located at Wright-Patterson Air Force Base, Ohio, LHMEL is managed by the Air Force Research Laboratory Materials Directorate AFRL/MLPJ and operated by Anteon Corporation. The facility's advanced hardware is centered around carbon dioxide lasers producing output power up to 135kW and neodymium glass lasers producing up to 10 kilojoules of repetitively pulsed output. The specific capabilities of each laser device and related optical systems are discussed. Materials testing capabilities coupled with the laser systems are also described including laser output and test specimen response diagnostics. Environmental simulation capabilities including wind tunnels and large-volume vacuum chambers relevant to beamed energy propulsion are also discussed. This paper concludes with a summary of the procedures and methods by which the facility can be accessed.

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.

21 CFR 179.43 - Carbon dioxide laser for etching food.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Carbon dioxide laser for etching food. 179.43 Section 179.43 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) IRRADIATION IN THE PRODUCTION, PROCESSING AND HANDLING OF...

21 CFR 179.43 - Carbon dioxide laser for etching food.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Carbon dioxide laser for etching food. 179.43 Section 179.43 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) IRRADIATION IN THE PRODUCTION, PROCESSING AND HANDLING OF FOOD Radiation and Radiation Sources...

Fast-axial turbulent flow CO2 laser output characteristics and scaling parameters

NASA Astrophysics Data System (ADS)

Dembovetsky, V. V.; Zavalova, Valentina Y.; Zavalov, Yuri N.

1996-04-01

The paper presents the experimental results of evaluating the output characteristics of TLA- 600 carbon-dioxide laser with axial turbulent gas flow, as well as the results of numerical modeling. The output characteristic and spatial distribution of laser beam were measured with regard to specific energy input, working mixture pressure, active media length and output mirror reflection. The paper presents the results of experimental and theoretical study and design decisions on a succession of similar type industrial carbon-dioxide lasers with fast-axial gas-flow and dc discharge excitation of active medium developed at NICTL RAN. As an illustration, characteristics of the TLA-600 laser are cited.

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.

Surface hardening using cw CO2 laser: laser heat treatment, modelation, and experimental work

NASA Astrophysics Data System (ADS)

Muniz, German; Alum, Jorge

1996-02-01

In the present work are given the results of the application of laser metal surface hardening techniques using a cw carbon dioxide laser as an energy source on steel 65 G. The laser heat treatment results are presented theoretically and experimentally. Continuous wave carbon dioxide laser of 0.6, 0.3, and 0.4 kW were used. A physical model for the descriptions of the thermophysical laser metal interactions process is given and a numerical algorithm is used to solve this problem by means of the LHT code. The results are compared with the corresponding experimental ones and a very good agreement is observed. The LHT code is able to do predictions of transformation hardening by laser heating. These results will be completed with other ones concerning laser alloying and cladding presented in a second paper.

Pulsed CO2 laser for intra-articular cartilage vaporization and subchondral bone perforation in horses

NASA Astrophysics Data System (ADS)

Nixon, Alan J.; Roth, Jerry E.; Krook, Lennart P.

1991-05-01

A pulsed carbon dioxide laser was used to vaporize articular cartilage in four horses, and perforate the cartilage and subchondral bone in four horses. Both intercarpal joints were examined arthroscopically and either a 1 cm cartilage crater or a series of holes was created in the third carpal bone of one joint. The contralateral carpus served as a control. The horses were evaluated clinically for 8 weeks, euthanatized and the joints examined radiographically, grossly, and histologically. Pulsed carbon dioxide laser vaporized cartilage readily but penetrated bone poorly. Cartilage vaporization resulted in no greater swelling, heat, pain on flexion, lameness, or synovial fluid reaction than the sham procedure. Laser drilling resulted in a shallow, charred hole with a tenacious carbon residue, and in combination with the thermal damage to deeper bone, resulted in increased swelling, mild lameness and a low-grade, but persistent synovitis. Cartilage removal by laser vaporization resulted in rapid regrowth with fibrous and fibrovascular tissue and occasional regions of fibrocartilage at week 8. The subchondral bone, synovial membrane, and draining lymph nodes appeared essentially unaffected by the laser cartilage vaporization procedure. Conversely, carbon dioxide laser drilling of subchondral bone resulted in poor penetration, extensive areas of thermal necrosis of bone, and significant secondary damage to the apposing articular surface of the radial carpal bone. The carbon dioxide laser is a useful intraarticular instrument for removal of cartilage and has potential application in inaccessible regions of diarthrodial joints. It does not penetrate bone sufficiently to have application in subchondral drilling.

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.

Temperature measurement using ultraviolet laser absorption of carbon dioxide behind shock waves.

PubMed

Oehlschlaeger, Matthew A; Davidson, David F; Jeffries, Jay B

2005-11-01

A diagnostic for microsecond time-resolved temperature measurements behind shock waves, using ultraviolet laser absorption of vibrationally hot carbon dioxide, is demonstrated. Continuous-wave laser radiation at 244 and 266 nm was employed to probe the spectrally smooth CO2 ultraviolet absorption, and an absorbance ratio technique was used to determine temperature. Measurements behind shock waves in both nonreacting and reacting (ignition) systems were made, and comparisons with isentropic and constant-volume calculations are reported.

Measurement of atmospheric carbon dioxide and water vapor in built-up urban areas in the Gandhinagar-Ahmedabad region in India using a portable tunable diode laser spectroscopy system.

PubMed

Roy, Anirban; Sharma, Neetesh Kumar; Chakraborty, Arup Lal; Upadhyay, Abhishek

2017-11-01

This paper reports open-path in situ measurements of atmospheric carbon dioxide at Gandhinagar (23.2156°N, 72.6369°E) and Ahmedabad (23.0225°N, 72.5714°E) in the heavily industrialized state of Gujarat in western India. Calibration-free second harmonic wavelength modulation spectroscopy (2f WMS) is used to carry out accurate and fully automated measurements. The mean values of the mole fraction of carbon dioxide at four locations were 438 ppm, 495 ppm, 550 ppm, and 740 ppm, respectively. These values are much higher than the current global average of 406.67 ppm. A 1 mW, 2004-nm vertical cavity surface-emitting laser is used to selectively interrogate the R16 transition of carbon dioxide at 2003.5 nm (4991.2585 cm -1 ). The 2f WMS signal corresponding to the gas absorption line shape is simulated using spectroscopic parameters available in the HITRAN database and relevant laser parameters that are extracted in situ from non-absorbing spectral wings of the harmonic signals. The mole fraction of carbon dioxide is extracted in real-time by a MATLAB program from least-squares fit of the simulated 2f WMS signal to the corresponding experimentally obtained signal. A 10-mW, 1392.54-nm distributed feedback laser is used at two of the locations to carry out water vapor measurements using direct absorption spectroscopy. This is the first instance of a portable tunable diode laser spectroscopy system being deployed in an urban location in India to measure atmospheric carbon dioxide and water vapor under varying traffic conditions. The measurements clearly demonstrate the need to adopt tunable diode laser spectroscopy for precise long-term monitoring of greenhouse gases in the Indian subcontinent.

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.

Role of laser myringotomy in a pediatric otolaryngology practice: initial experience

NASA Astrophysics Data System (ADS)

Shah, Udayan K.

2001-05-01

A new technology (OtoLAM) to fenestrate the tympanic membrane with the carbon dioxide laser (CO2), in the office or the operating room, has been introduced over the last three years. While not new conceptually, this product offers the ability to easily create a precise window into the middle ear using a portable system. Controversy regarding the indications and benefits of this technique, amplified by the costs of the system and the marketing of the technology prior to extensive clinical testing, has plagued the clinical application of this technology. We report our experience over the past year with this system in a busy pediatric otolaryngology practice. Laser fenestration of the tympanic membrane has been useful for the insertion of tympanostomy tubes, and for the minimally invasive evaluation of the middle ear. Our small experience to date reveals that there is a limited role for laser tympanic membrane fenestration in a busy pediatric otolaryngology practice.

Passive Q switching and mode-locking of Er:glass lasers using VO2 mirrors

NASA Astrophysics Data System (ADS)

Pollack, S. A.; Chang, D. B.; Chudnovky, F. A.; Khakhaev, I. A.

1995-09-01

Passive Q switching of an Er:glass laser with the pulse width varying between 14 and 80 ns has been demonstrated, using three resonator vanadium-dioxide-coated (VO2) mirror samples with temperature-dependent reflectivity and differing in the reflectivity contrast. The reflectivity changes because of a phase transition from a semiconductor to a metallic state. Broad band operating characteristics of VO2 mirrors provide Q switching over a wide range of wavelengths. In addition, mode-locked pulses with much shorter time scales have been observed, due to exciton formation and recombination. A simple criterion is derived for the allowable ambient temperatures at which the Q switching operates effectively. A simple relation has also been found relating the duration of the Q-switched pulse to the contrast in reflectivities of the two mirror phases.

Progress on High-Energy 2-micron Solid State Laser for NASA Space-Based Wind and Carbon Dioxide Measurements

NASA Technical Reports Server (NTRS)

Singh, Upendra N.

2011-01-01

Sustained research efforts at NASA Langley Research Center during last fifteen years have resulted in significant advancement of a 2-micron diode-pumped, solid-state laser transmitter for wind and carbon dioxide measurements from ground, air and space-borne platforms. Solid-state 2-micron laser is a key subsystem for a coherent Doppler lidar that measures the horizontal and vertical wind velocities with high precision and resolution. The same laser, after a few modifications, can also be used in a Differential Absorption Lidar system for measuring atmospheric CO2 concentration profiles. Researchers at NASA Langley Research Center have developed a compact, flight capable, high energy, injection seeded, 2-micron laser transmitter for ground and airborne wind and carbon dioxide measurements. It is capable of producing 250 mJ at 10 Hz by an oscillator and one amplifier. This compact laser transmitter was integrated into a mobile trailer based coherent Doppler wind and CO2 DIAL system and was deployed during field measurement campaigns. This paper will give an overview of 2-micron solid-state laser technology development and discuss results from recent ground-based field measurements.

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.

Mapping Mars with a Laser Altimeter

NASA Technical Reports Server (NTRS)

Smith, David E.

2001-01-01

In November 1996 the Mars Global Surveyor (MGS) spacecraft was launched to Mars. One of the instruments on the spacecraft was a laser altimeter, MOLA, for measuring the shape and topography of the planet. The altimeter has a diode pumped Q-switched ND:YAG laser at 1064nm, operating at 10Hz with an 8 nsec pulse width. The pulse energy is 48mJ, and the instrument has a 37cm ranging precision. The laser illuminates a spot on the surface of Mars approximately 160 meters in diameter and the instrument has accumulated over 600 million range measurements of the surface since arrival at Mars in September 1997. MOLA has operated continuously for over 2 years and has mapped the planet at a horizontal resolution of about 1 km and a radial accuracy of about a meter. MOLA has measured the shape of the planet, the heights of the volcanoes, the depths of the canyons, and the volumes of the polar icecaps. It has detected carbon dioxide clouds and measured the accumulation of seasonal CO2 on the polar icecaps. This new remote sensing tool has helped transform our understanding of Mars and its geological history, and opened a new door to planetary exploration.

Carbon dioxide sequestration monitoring and verification via laser based detection system in the 2 mum band

NASA Astrophysics Data System (ADS)

Humphries, Seth David

Carbon Dioxide (CO2) is a known contributor to the green house gas effect. Emissions of CO2 are rising as the global demand for inexpensive energy is placated through the consumption and combustion of fossil fuels. Carbon capture and sequestration (CCS) may provide a method to prevent CO2 from being exhausted to the atmosphere. The carbon may be captured after fossil fuel combustion in a power plant and then stored in a long term facility such as a deep geologic feature. The ability to verify the integrity of carbon storage at a location is key to the success of all CCS projects. A laser-based instrument has been built and tested at Montana State University (MSU) to measure CO2 concentrations above a carbon storage location. The CO2 Detection by Differential Absorption (CODDA) Instrument uses a temperature-tunable distributed feedback (DFB) laser diode that is capable of accessing a spectral region, 2.0027 to 2.0042 mum, that contains three CO2 absorption lines and a water vapor absorption line. This instrument laser is aimed over an open-air, two-way path of about 100 m, allowing measurements of CO2 concentrations to be made directly above a carbon dioxide release test site. The performance of the instrument for carbon sequestration site monitoring is studied using a newly developed CO2 controlled release facility. The field and CO2 releases are managed by the Zero Emissions Research Technology (ZERT) group at MSU. Two test injections were carried out through vertical wells simulating seepage up well paths. Three test injections were done as CO2 escaped up through a slotted horizontal pipe simulating seepage up through geologic fault zones. The results from these 5 separate controlled release experiments over the course of three summers show that the CODDA Instrument is clearly capable of verifying the integrity of full-scale CO2 storage operations.

Formation of porous silicon oxide from substrate-bound silicon rich silicon oxide layers by continuous-wave laser irradiation

NASA Astrophysics Data System (ADS)

Wang, Nan; Fricke-Begemann, Th.; Peretzki, P.; Ihlemann, J.; Seibt, M.

2018-03-01

Silicon nanocrystals embedded in silicon oxide that show room temperature photoluminescence (PL) have great potential in silicon light emission applications. Nanocrystalline silicon particle formation by laser irradiation has the unique advantage of spatially controlled heating, which is compatible with modern silicon micro-fabrication technology. In this paper, we employ continuous wave laser irradiation to decompose substrate-bound silicon-rich silicon oxide films into crystalline silicon particles and silicon dioxide. The resulting microstructure is studied using transmission electron microscopy techniques with considerable emphasis on the formation and properties of laser damaged regions which typically quench room temperature PL from the nanoparticles. It is shown that such regions consist of an amorphous matrix with a composition similar to silicon dioxide which contains some nanometric silicon particles in addition to pores. A mechanism referred to as "selective silicon ablation" is proposed which consistently explains the experimental observations. Implications for the damage-free laser decomposition of silicon-rich silicon oxides and also for controlled production of porous silicon dioxide films are discussed.

Comparison of the effect of the carbon dioxide laser and the bipolar coagulator on the cat brain

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

Cozzens, J.W.; Cerullo, L.J.

The carbon dioxide laser has recently received clinical acceptance in neurosurgical practice. There are, however, few studies reported in the neurosurgical literature, either clinical or experimental, concerning its safety or efficacy on a physiological level by comparison to a more conventional tool. This study is not a description of a surgical technique, but is rather a basic physiological comparison of two surgical instruments. In this study, 11 cats were pretreated with the protein-bound dye, Evans blue. A corticotomy was performed in one hemisphere with the carbon dioxide laser and in the other with a microbipolar coagulator and a sharp blade.more » The subsequent extravasation of dye was presumed to be proportional to the amount of blood-brain barrier disruption associated with each lesion. When effective power settings for the two devices were compared, the laser lesions had significantly less extravasation of blue dye. This indicated that there was less damage to the blood-brain barrier surrounding laser corticotomy than surrounding conventional bipolar coagulation and sharp dissection at comparable power settings for each modality.« less

Laser-Based Monitoring of CH4, CO2, NH3, and H2S in Animal Farming—System Characterization and Initial Demonstration

PubMed Central

Jaworski, Piotr; Nikodem, Michał

2018-01-01

In this paper, we present a system for sequential detection of multiple gases using laser-based wavelength modulation spectroscopy (WMS) method combined with a Herriot-type multi-pass cell. Concentration of hydrogen sulfide (H2S), methane (CH4), carbon dioxide (CO2), and ammonia (NH3) are retrieved using three distributed feedback laser diodes operating at 1574.5 nm (H2S and CO2), 1651 nm (CH4), and 1531 nm (NH3). Careful adjustment of system parameters allows for H2S sensing at single parts-per-million by volume (ppmv) level with strongly reduced interference from adjacent CO2 transitions even at atmospheric pressure. System characterization in laboratory conditions is presented and the results from initial tests in real-world application are demonstrated. PMID:29425175

Single-mode interband cascade laser multiemitter structure for two-wavelength absorption spectroscopy

NASA Astrophysics Data System (ADS)

Scheuermann, Julian; Weih, Robert; Becker, Steffen; Fischer, Marc; Koeth, Johannes; Höfling, Sven

2018-01-01

An interband cascade laser multiemitter with single-mode distributed feedback (DFB) emission at two wavelengths is presented. Continuous-wave laser operation is measured from 0°C to 40°C with threshold currents of around 25 mA and output powers of around 9 mW at 20°C. The ridge waveguide DFB structures are monolithically integrated with a spacing of 70 μm and each is provided with an individual metal DFB grating to select specific single-mode wavelengths of interest for absorption spectroscopy. The emission windows at 3.92 and 4.01 μm are targeting hydrogen sulfide and sulfur dioxide, which are of importance for industrial applications since both gases are reagents of the Claus process in sulfur recovery units, recovering elemental sulfur from gaseous hydrogen sulfide.

Airborne Measurements of Atmospheric Methane Using Pulsed Laser Transmitters

NASA Technical Reports Server (NTRS)

Numata, Kenji; Riris, Haris; Wu, Stewart; Gonzalez, Brayler; Rodriguez, Michael; Hasselbrack, William; Fahey, Molly; Yu, Anthony; Stephen, Mark; Mao, Jianping;

Exostosis following a subepithelial connective tissue graft.

PubMed

Corsair, A J; Iacono, V J; Moss, S S

2001-04-01

This case report describes the formation of an unusual unaesthetic gingival enlargement during a five year post operative period subsequent to a subepithelial connective tissue graft placed facial to teeth #4 and #6. Histological assessment of the enlarged tissue indicated that it consisted of viable bone and marrow. The exostosis was reduced with rotary instruments and acceptable soft tissue aesthetics were created using a carbon dioxide laser for gingivoplasty. Possible causes for this unusual enlargement are discussed.

Maintenance of arytenoid abduction following carbon dioxide laser debridement of the articular cartilage and joint capsule of the cricoarytenoid joint combined with prosthetic laryngoplasty in horses: an in vivo and in vitro study.

PubMed

Hawkins, J F; Couetil, L; Miller, M A

2014-02-01

The objective was to evaluate CO2 laser debridement of the cricoarytenoid joint (CAJ) combined with prosthetic laryngoplasty to prevent post-operative loss of arytenoid abduction in seven horses. Horses were assigned to either laser debridement of the left CAJ and laryngoplasty (laser treated, n=5) or control laryngoplasty (sham, n=2), and were evaluated with endoscopic examinations and measurement of right to left angle quotients (RLQ) to assess maintenance of arytenoid abduction. The animals were euthanased at intervals after surgery and larynges were harvested for post-mortem testing, including determination of translaryngeal flow, pressure, impedance and RLQ. Measurements were obtained under increasing vacuum-generated negative pressure with laryngoplasty sutures intact and with the knot/crimp of the laryngoplasty sutures removed. Following post-mortem testing the cricoarytenoid joints were examined histologically. Post-operative endoscopic examinations revealed no significant differences between RLQ measurements calculated for day 1 following surgery to the termination date of the study for the seven horses. Post-mortem RLQ at airflows of 10 and 60 L/s was significantly higher in sham than in laser treated horses both before and after knot/crimp removal. Translaryngeal impedance at 10 and 60 L/s was not statistically different between groups. Histopathology revealed necrosis and loss of articular cartilage in the laser treated horses. The lymphoid cell infiltration subsided but joint capsule and periarticular fibrosis increased over the course of the study. Post-operative loss of arytenoid abduction after laryngoplasty can be minimized with CO2 laser debridement of the CAJ joint. Copyright © 2013 Elsevier Ltd. All rights reserved.

Multi-Wavelength Measurement of Bus Exhausts Using a Four QC Laser Spectrometer

NASA Astrophysics Data System (ADS)

Hay, K. G.; Wilson, D.; Duxbury, G.; Langford, N.

2010-06-01

Using a portable, lightweight, four laser intra-pulse quantum cascade laser spectrometer we have measured the variation of the composition of exhaust gases emitted by diesel engined buses which are representative of the decades from the 1930's until the 1990's. The lasers and the fast detector used in the spectrometer are Peltier cooled, and the spectra are recorded using each laser in turn, in a repeated four laser cycle. The instrument is controlled via a ruggedised laptop computer. The wavelengths of the lasers used were 7.84 microns (methane, nitrous oxide and formaldehyde), 6.13 microns (nitrogen dioxide) 5.25 microns (nitric oxide and water) and 4.88 microns (carbon monoxide and carbon dioxide). The path length of the multiple pass absorption cell used was 77 m. The results we will present demonstrate the possibility of deploying this type of instrument for investigating gas emissions from a variety of sources.

Large tuning of narrow-beam terahertz plasmonic lasers operating at 78 K

DOE PAGES

Wu, Chongzhao; Jin, Yuan; Reno, John L.; ...

2016-12-19

A new tuning mechanism is demonstrated for single-mode metal-clad plasmonic lasers, in which the refractive-index of the laser’s surrounding medium affects the resonant-cavity mode in the same vein as the refractive-index of gain medium inside the cavity. Reversible, continuous, and mode-hop-free tuning of ~57 GHz is realized for single-mode narrow-beam terahertz plasmonic quantum-cascade lasers (QCLs), which is demonstrated at a much more practical temperature of 78 K. The tuning is based on post-process deposition/etching of a dielectric (silicon-dioxide) on a QCL chip that has already been soldered and wire-bonded onto a copper mount. This is a considerably larger tuning rangemore » compared to previously reported results for terahertz QCLs with directional far-field radiation patterns. The key enabling mechanism for tuning is a recently developed antenna-feedback scheme for plasmonic lasers, which leads to the generation of hybrid surface-plasmon-polaritons propagating outside the cavity of the laser with a large spatial extent. The effect of dielectric deposition on QCL’s characteristics is investigated in detail including that on maximum operating temperature, peak output power, and far-field radiation patterns. Single-lobed beam with low divergence (<7°) is maintained through the tuning range. The antenna-feedback scheme is ideally suited for modulation of plasmonic lasers and their sensing applications due to the sensitive dependence of spectral and radiative properties of the laser on its surrounding medium.« less

21 CFR 884.4550 - Gynecologic surgical laser.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Gynecologic surgical laser. 884.4550 Section 884....4550 Gynecologic surgical laser. (a) Identification. A gynecologic surgical laser is a continuous wave carbon dioxide laser designed to destroy tissue thermally or to remove tissue by radiant light energy...

21 CFR 884.4550 - Gynecologic surgical laser.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Gynecologic surgical laser. 884.4550 Section 884....4550 Gynecologic surgical laser. (a) Identification. A gynecologic surgical laser is a continuous wave carbon dioxide laser designed to destroy tissue thermally or to remove tissue by radiant light energy...

21 CFR 884.4550 - Gynecologic surgical laser.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Gynecologic surgical laser. 884.4550 Section 884....4550 Gynecologic surgical laser. (a) Identification. A gynecologic surgical laser is a continuous wave carbon dioxide laser designed to destroy tissue thermally or to remove tissue by radiant light energy...

21 CFR 884.4550 - Gynecologic surgical laser.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Gynecologic surgical laser. 884.4550 Section 884....4550 Gynecologic surgical laser. (a) Identification. A gynecologic surgical laser is a continuous wave carbon dioxide laser designed to destroy tissue thermally or to remove tissue by radiant light energy...

21 CFR 884.4550 - Gynecologic surgical laser.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Gynecologic surgical laser. 884.4550 Section 884....4550 Gynecologic surgical laser. (a) Identification. A gynecologic surgical laser is a continuous wave carbon dioxide laser designed to destroy tissue thermally or to remove tissue by radiant light energy...

Phase Aberrations And Beam Cleanup Techniques In Carbon-Dioxide Laser Fusion Systems

NASA Astrophysics Data System (ADS)

Viswanathan, V. K.

1981-12-01

This paper describes the various carbon dioxide laser fusion systems at Los Alamos from the point of view of an optical designer. The types of phase aberrations present in these systems, as well as the beam cleanup techniques that can be used to improve the beam optical quality, are discussed. As this is a review article, some previously published results are also used where relevant.

Design of a high pulse repitition frequency carbon dioxide laser for processing high damage threshold materials

NASA Astrophysics Data System (ADS)

Chatwin, Christopher R.; McDonald, Donald W.; Scott, Brian F.

1989-07-01

The absence of an applications led design philosophy has compromised both the development of laser source technology and its effective implementation into manufacturing technology in particular. For example, CO2 lasers are still incapable of processing classes of refractory and non-ferrous metals. Whilst the scope of this paper is restricted to high power CO2 lasers; the design methodology reported herein is applicable to source technology in general, which when exploited, will effect an expansion of applications. The CO2 laser operational envelope should not only be expanded to incorporate high damage threshold materials but also offer a greater degree of controllability. By a combination of modelling and experimentation the requisite beam characteristics, at the workpiece, were determined then utilised to design the Laser Manufacturing System. The design of sub-system elements was achieved by a combination of experimentation and simulation which benefited from a comprehensive set of software tools. By linking these tools the physical processes in the laser - electron processes in the plasma, the history of photons in the resonator, etc. - can be related, in a detailed model, to the heating mechanisms in the workpiece.

Monitoring the inhibition of erosion by a CO2 laser with OCT

NASA Astrophysics Data System (ADS)

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

2014-02-01

Since optical coherence tomography (OCT) is well suited for measuring small dimensional changes on tooth surfaces, OCT has great potential for monitoring tooth erosion. Previous studies have shown that enamel areas ablated by a carbon dioxide laser manifested lower rates of erosion compared to the nonablated areas. The purpose of this study was to develop a model to monitor erosion in vitro that could potentially be used in vivo. Teeth surfaces were irradiated with a carbon dioxide laser at low sub-ablative fluence to create an acid-resistant reference layer without damaging the enamel. The laser treated areas were compared with the unprotected areas using OCT during exposure to a pH cycling model for up to 6 days. The laser treated areas markedly reduced the rate of erosion.

Application of the UV laser printing technique to soft gelatin capsules containing titanium dioxide in the shells.

PubMed

Hosokawa, Akihiro; Kato, Yoshiteru

2012-03-01

The purpose of this study was to examine application of ultraviolet (UV) laser irradiation to printing soft gelatin capsules containing titanium dioxide (TiO(2)) in the shells and to study effect of UV laser power on the color strength of printing on the soft gelatin capsules. Size 6 Oval type soft gelatin capsules of which shells contained 0.685% TiO(2) and 0.005% ferric dioxide were used in this study. The capsules were irradiated pulsed UV laser at a wavelength 355 nm. The color strength of the printed capsules was determined by a spectrophotometer as total color difference (dE). The soft gelatin capsules which contained TiO(2) in the shells could be printed gray by the laser. Many black particles, which were associated with the printing, were formed at the colored parts of the shells. It was found that there were two inflection points in relationship between output laser energy of a pulse and dE. Below the lower point, the capsules were not printed. From the lower point to the upper point, the capsules were printed gray and total color difference of the printing increased linearly in proportion with the output laser energy. Beyond the upper point, total color difference showed saturation because of micro-bubbles formation at the laser irradiated spot. Soft gelatin capsules containing TiO(2) in the shells could be performed stable printing using the UV laser printing technique. Color strength of the printing could be controlled by regulating the laser energy between the two inflection points.

The airborne Laser Absorption Spectrometer - A new instrument of remote measurement of atmospheric trace gases

NASA Technical Reports Server (NTRS)

Shumate, M. S.; Menzies, R. T.

1978-01-01

The Laser Absorption Spectrometer is a portable instrument developed by JPL for remote measurement of trace gases from an aircraft platform. It contains two carbon dioxide lasers, two optical heterodyne receivers, appropriate optics to aim the lasers at the ground and detect the backscattered energy, and signal processing and recording electronics. Operating in the differential-absorption mode, it is possible to monitor one atmospheric gas at a time and record the data in real time. The system can presently measure ozone, ethylene, water vapor, and chlorofluoromethanes with high sensitivity. Airborne measurements were made in early 1977 from the NASA/JPL twin-engine Beechcraft and in May 1977 from the NASA Convair 990 during the ASSESS-II Shuttle Simulation Study. These flights resulted in measurements of ozone concentrations in the lower troposphere which were compared with ground-based values provided by the Air Pollution Control District. This paper describes the details of the instrument and results of the airborne measurements.

Technology Advancement for Active Remote Sensing of Carbon Dioxide from Space Using the ASCENDS CarbonHawk Experiment Simulator: First Results

NASA Technical Reports Server (NTRS)

Obland, Michael D.; Nehrir, Amin R.; Lin, Bing; Harrison, F. Wallace; Kooi, Susan; Choi, Yonghoon; Plant, James; Yang, Melissa; Antill, Charles; Campbell, Joel;

Nitrogen dioxide and kerosene-flame soot calibration of photoacoustic instruments for measurement of light absorption by aerosols

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

Arnott, W. Patrick; Moosmu''ller, Hans; Walker, John W.

2000-12-01

A nitrogen dioxide calibration method is developed to evaluate the theoretical calibration for a photoacoustic instrument used to measure light absorption by atmospheric aerosols at a laser wavelength of 532.0 nm. This method uses high concentrations of nitrogen dioxide so that both a simple extinction and the photoacoustically obtained absorption measurement may be performed simultaneously. Since Rayleigh scattering is much less than absorption for the gas, the agreement between the extinction and absorption coefficients can be used to evaluate the theoretical calibration, so that the laser gas spectra are not needed. Photoacoustic theory is developed to account for strong absorptionmore » of the laser beam power in passage through the resonator. Findings are that the photoacoustic absorption based on heat-balance theory for the instrument compares well with absorption inferred from the extinction measurement, and that both are well within values represented by published spectra of nitrogen dioxide. Photodissociation of nitrogen dioxide limits the calibration method to wavelengths longer than 398 nm. Extinction and absorption at 532 and 1047 nm were measured for kerosene-flame soot to evaluate the calibration method, and the single scattering albedo was found to be 0.31 and 0.20 at these wavelengths, respectively.« less

Lasers '92; Proceedings of the International Conference on Lasers and Applications, 15th, Houston, TX, Dec. 7-10, 1992

NASA Technical Reports Server (NTRS)

Wang, Charles P. (Editor)

1993-01-01

Papers from the conference are presented, and the topics covered include the following: x-ray lasers, excimer lasers, chemical lasers, high power lasers, blue-green lasers, dye lasers, solid state lasers, semiconductor lasers, gas and discharge lasers, carbon dioxide lasers, ultrafast phenomena, nonlinear optics, quantum optics, dynamic gratings and wave mixing, laser radar, lasers in medicine, optical filters and laser communication, optical techniques and instruments, laser material interaction, and industrial and manufacturing applications.

Visualization of transient phenomena during the interaction of pulsed CO2 laser radiation with matter

NASA Astrophysics Data System (ADS)

Schmitt, R.; Hugenschmidt, Manfred

1996-05-01

Carbon-dioxide-lasers operating in the pulsed mode with energy densities up to several tens of J/cm2 and peak power densities in the multi-MW/cm2-range may cause fast heating and melting. Eventually quasi-explosive ejection, decomposition or vaporization of material can be observed. Surface plasmas are strongly influencing the energy transfer from the laser radiation field to any target. For optically transparent plastics, such as PMMA for example, only slowly expanding plasmas (LSC-waves) are ignited at fluences around 20 J/cm2, with a low level of self-luminosity. High brightness, supersonically expanding plasma jets (LSD-waves) are generated at the same fluences on glasses. Similar conditions were found for metals as well. From recordings with a high speed CCD-camera, interesting features concerning the initial plasma phases and temporal evolution were deduced. Additionally, information was obtained concerning the quasi explosive ejection of material for PMMA.

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.

High Power Laser Processing Of Materials

NASA Astrophysics Data System (ADS)

Martyr, D. R.; Holt, T.

1987-09-01

The first practical demonstration of a laser device was in 1960 and in the following years, the high power carbon dioxide laser has matured as an industrial machine tool. Modern carbon dioxide gas lasers can be used for cutting, welding, heat treatment, drilling, scribing and marking. Since their invention over 25 years ago they are now becoming recognised as highly reliable devices capable of achieving huge savings in production costs in many situations. This paper introduces the basic laser processing techniques of cutting, welding and heat treatment as they apply to the most common engineering materials. Typical processing speeds achieved with a wide range of laser powers are reported. Accuracies achievable and fit-up tolerances required are presented. Methods of integrating lasers with machine tools are described and their suitability in a wide range of manufacturing industries is described by reference to recent installations. Examples from small batch manufacturing, high volume production using dedicated laser welding equipment, and high volume manufacturing using 'flexible' automated laser welding equipment are described Future applications of laser processing are suggested by reference to current process developments.

Stabilized Lasers and Precision Measurements.

ERIC Educational Resources Information Center

Hall, J. L.

1978-01-01

Traces the development of stabilized lasers from the Massachusetts Institute of Technology passive-stabilization experiments of the early 1960s up through the current epoch of highly stabilized helium-neon and carbon dioxide and continuous wave dye lasers. (Author/HM)

Carbon dioxide laser management cervical intraepithelial neoplasia

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

Bellina, J.H.; Wright, V.C.; Voros, J.I.

1981-12-01

In this report we describe the use of the carbon dioxide laser for the outpatient management of cervical intraepithelial neoplasia (CIN). A comparison of treatment effectiveness for different grades of CIN is also included. Two hundred fifty-six cases were evaluated by colposcopy, cytology, and histopathology, treated by at least 5 to 6 mm of laser vaporization, and followed up for an average of 10.7 months. Follow-up examinations included cytology, colposcopy, and directed biopsy if a suspicious lesion was discovered. During the follow-up, 18 cases of persistent CIN were identified (7.0%). Most of these were successfully managed with repeat laser treatment.more » Overall success of laser surgery for CIN, one or two applications, was 97.6%. Few complications were encountered. Laser surgery appears to offer acceptable treatment effectiveness, early identification of persistent disease, and easy retreatment when required. (Am. J. Obstet. Gynecol. 141:828, 1981.)« less

Carbon dioxide laser effects on caries-like lesions of dental enamel

NASA Astrophysics Data System (ADS)

Featherstone, John D. B.; Zhang, S. H.; Shariati, M.; McCormack, Sandra M.

1991-05-01

Previous studies by the authors have shown that carbon dioxide (CO2) laser light has marked effects on dental hard tissues and that these effects are wavelength-dependent. The aim of the present study was to determine whether treatment by CO2 laser of caries-like lesions in human enamel would inhibit subsequent lesion progression. Nine groups of 10 teeth each with preformed caries-like lesions were treated with/without CO2 laser (9.32 micrometers , 15 mJ or 25 mJ per pulse) by a pulsed laser (100-200 nsec) for either 200 or 400 pulses. Preformed lesions were then treated with acidulated phosphate fluoride for 5 minutes with control groups with no fluoride treatment. Teeth were subjected to a subsequent pH cycling challenge to determine the protection against lesion progression. Low energy laser treatment coupled with fluoride treatment entirely inhibited subsequent lesion progression in this model system.

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.

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.

Quad quantum cascade laser spectrometer with dual gas cells for the simultaneous analysis of mainstream and sidestream cigarette smoke

NASA Astrophysics Data System (ADS)

Baren, Randall E.; Parrish, Milton E.; Shafer, Kenneth H.; Harward, Charles N.; Shi, Quan; Nelson, David D.; McManus, J. Barry; Zahniser, Mark S.

2004-12-01

A compact, fast response, infrared spectrometer using four pulsed quantum cascade (QC) lasers has been applied to the analysis of gases in mainstream (MS) and sidestream (SS) cigarette smoke. QC lasers have many advantages over the traditional lead-salt tunable diode lasers, including near room temperature operation with thermoelectric cooling and single mode operation with improved long-term stability. The new instrument uses two 36 m, 0.3 l multiple pass absorption gas cells to obtain a time response of 0.1 s for the MS smoke system and 0.4 s for the SS smoke system. The concentrations of ammonia, ethylene, nitric oxide, and carbon dioxide for three different reference cigarettes were measured simultaneously in MS and SS smoke. A data rate of 20 Hz provides sufficient resolution to determine the concentration profiles during each 2 s puff in the MS smoke. Concentration profiles before, during and after the puffs also have been observed for these smoke constituents in SS smoke. Also, simultaneous measurements of CO 2 from a non-dispersive infrared (NDIR) analyzer are obtained for both MS and SS smoke. In addition, during this work, nitrous oxide was detected in both the MS and SS smoke for all reference cigarettes studied.

Excellent Aesthetic and Functional Outcome After Fractionated Carbon Dioxide Laser Skin Graft Revision Surgery: Case Report and Review of Laser Skin Graft Revision Techniques.

PubMed

Ho, Derek; Jagdeo, Jared

2015-11-01

Skin grafts are utilized in dermatology to reconstruct a defect secondary to surgery or trauma of the skin. Common indications for skin grafts include surgical removal of cutaneous malignancies, replacement of tissue after burns or lacerations, and hair transplantation in alopecia. Skin grafts may be cosmetically displeasing, functionally limiting, and significantly impact patient's quality-of-life. There is limited published data regarding skin graft revision to enhance aesthetics and function. Here, we present a case demonstrating excellent aesthetic and functional outcome after fractionated carbon dioxide (CO2) laser skin graft revision surgery and review of the medical literature on laser skin graft revision techniques.

Thermoinduced laser-assisted deposition of molybdenum from aqueous solutions

NASA Astrophysics Data System (ADS)

Kochemirovsky, Vladimir V.; Logunov, Lev S.; Zhigley, Elvira S.; Baranauskaite, Valeriia

2015-05-01

Local molybdenum deposit obtainment is promising for micro thermocouples creation on dielectric surfaces. This paper is dedicated to development of method of laser-induced molybdenum deposition from water-based solution of inorganic salt on Sitall st-50 and glass dielectric substrates, as well as research of solution composition, pH and substrate optical properties influence on result of laser-induced molybdenum deposition from solution. It was shown that depending on dielectric substrate type, as a result of laser-induced deposition metallic molybdenum or molybdenum dioxide deposit forms: molybdenum dioxide deposits in case of optically clear substrate and metallic molybdenum deposits in case of opaque glass-ceramics. While modelling interim case via using clouded glass, mixture of molybdenum and its oxide was successfully obtained.

Lasers in otorhinolaryngology

NASA Astrophysics Data System (ADS)

Pais Clemente, Manuel P.

1992-03-01

Lasers are now commonly accepted and widely used surgical instruments in otorhinolaryngology. There have been a great number of technological advances with lasers that have contributed to the expansion of this new surgical modality with an increased number of medical applications. Surgical strategies have also changed and are more favorable toward conservative surgery in which less tissues is removed than with more radical resections. This combination of improving technology and medical attitudes has changed the field of otorhinolaryngology, and resulted in an expanding use of laser surgery. Since 1973 we have been using the carbon dioxide laser in the treatment of diseases of the upper aero digestive systems, learning this new surgical technique from the pioneer work of Strong, Jako, and Vaughan. It is our conviction that a laser surgeon must have a thorough knowledge of laser biophysics, instrumentation, safety protocols, and surgical indications, and have the technical skills to perform laser surgery. Laser technology continues to improve at an increased speed, and it is imperative to update knowledge of current and potential applications of lasers in our specialty. It is the purpose of this article to present our clinical experience of 18 years with the use of lasers in surgery of ORL, emphasizing the carbon dioxide laser.

Titanium Dioxide (TiO2) film as a new saturable absorber for generating mode-locked Thulium-Holmium doped all-fiber laser

NASA Astrophysics Data System (ADS)

Mohd Rusdi, Muhammad Farid; Latiff, Anas Abdul; Paul, Mukul Chandra; Das, Shyamal; Dhar, Anirban; Ahmad, Harith; Harun, Sulaiman Wadi

2017-03-01

We report the generation of mode-locked thulium-holmium doped fiber laser (THDFL) at 1979 nm. This is a first demonstration of mode-locked by using Titanium Dioxide (TiO2) film as a saturable absorber (SA). A piece of 1 mm×1 mm TiO2 film was sandwiched in between two fiber ferrule in the cavity. Fabrication process of TiO2 film incorporated a TiO2 and a polyvinyl alcohol (PVA). The stable 9 MHz repetition rate of mode-locked mode operation with 58 dB SNR was generated under pump power of 902-1062 mW. At maximum pump power, the mode-locked THDFL has output power and pulse energy of 15 mW and 1.66 nJ, respectively. Our results demonstrate the TiO2 can be used promisingly in ultrafast photonics applications.

Effects of pulsed CO2 laser in caries selective ablation

NASA Astrophysics Data System (ADS)

Colojoara, Carmen; David, Ion; Marinovici, Mariana

1995-03-01

We have evaluated the effect of pulsed carbon dioxide laser in the treatment for deep carious decay. The so called `caries profonda' is still a problem for conservative dentistry. A `Valvfivre' Master 20S carbon dioxide laser was pulsed to determine the effects on dentine and for testing the properties of softened dentine in selective ablation. Laser treatment parameters were from 1 to 2 W, 50 to 150 ms, 200 to 320 Hz. Fifteen human teeth samples were exposed to irradiation: extracted third molar were exposed to CO2 pulsed laser to determine in vitro the effects on pulp morphology. The tissue samples were analyzed histologically and by means of scanning electron microscopy for evidence of thermal damage. Next, we have evaluated the morphologic changes in vivo on 10 cases in patients with deep carious decay. Pulsed infrared lasers are capable of inducing physical and chemical changes in dentine structure. The results showed an artificially sclerosing and micro-hardness on the remaining dentine. CO2 laser can vaporized carious dentine.

Laser Doppler detection systems for gas velocity measurement.

PubMed

Huffaker, R M

1970-05-01

The velocity of gas flow has been remotely measured using a technique which involves the coherent detection of scattered laser radiation from small particles suspended in the fluid utilizing the doppler effect. Suitable instrumentation for the study of wind tunnel type and atmospheric flows are described. Mainly for reasons of spatial resolution, a function of the laser wavelength, the wind tunnel system utilizes an argon laser operating at 0.5 micro. The relaxed spatial resolution requirement of atmospheric applications allows the use of a carbon dioxide laser, which has superior performance at a wavelength of 10.6 micro, a deduction made from signal-to-noise ratio considerations. Theoretical design considerations are given which consider Mie scattering predictions, two-phase flow effects, photomixing fundamentals, laser selection, spatial resolution, and spectral broadening effects. Preliminary experimental investigations using the instrumentation are detailed. The velocity profile of the flow field generated by a 1.27-cm diam subsonic jet was investigated, and the result compared favorably with a hot wire investigation conducted in the same jet. Measurements of wind velocity at a range of 50 m have also shown the considerable promise of the atmospheric system.

Investigation of the Effects of MIR-FELIrradiation on the Photoluminescence of Titanium Dioxides

NASA Astrophysics Data System (ADS)

Sonobe, T.; Bakr, M.; Yoshida, K.; Higashimura, K.; Kinjo, R.; Hachiya, K.; Kii, T.; Masuda, K.; Ohgaki, H.

2010-02-01

A mid-infrared free electron laser (MIR-FEL: 5 μm-20 μm) facility (KU-FEL: Kyoto University Free Electron Laser) has been constructed in Institute of Advanced Energy Kyoto University, and first laser saturation at 13.2 μm was achieved in May 2008. Currently, we have started to develop the application of MIR-FEL in the field of energy and material science. This study aimed at investigating the feasibility for the development of new evaluation technique of electron-phonon interaction in metal oxides by MIR-FEL. A preliminary result of electrical and optical properties of titanium dioxides was presented.

CO2-laser-assisted microsurgical anastomosis in reconstructive microsurgery

NASA Astrophysics Data System (ADS)

Kiyoshige, Yoshiro

1996-01-01

Since 1984, the author used a low output carbon dioxide laser for microsurgical anastomoses in the experimental investigation with rats. The series of experiments demonstrates the following characteristics, in comparison with conventional microsurgical anastomoses: ease in technique; less time consumption; equivalency of patency rate and bursting pressure; but only about 50% of the tensile strength of manual suture anastomosis. These findings suggested that low output carbon dioxide laser has the potential for clinical application. Then this technique has been applied in six clinical cases with digital replantations and free vascularized flap since 1988. The procedure offers increased safety and speed in reconstructive microsurgery.

In vitro comparison of debonding force and intrapulpal temperature changes during ceramic orthodontic bracket removal using a carbon dioxide laser.

PubMed

Ma, T; Marangoni, R D; Flint, W

1997-02-01

The aim of this study was to develop a method to reduce the fracture of ceramic orthodontics brackets during debonding procedures. Lasers have been used to thermally soften the bonding resin, which reduces the tensile debonding force. Thermal effects of lasers may create adverse effects to the dental pulp. Previous studies have shown that no pulpal injury occurs when the maximum intrapulpal temperature rise stayed below 2 degrees C. This study investigated the effect of lasing time on intrapulpal temperature increase and tensile debonding force with a 18 watt carbon dioxide laser. Ceramic brackets were bonded to mandibular deciduous bovine teeth and human mandibular first premolars with a photoactivated bonding resin. Modified debonding pliers was used to accurately position the laser beam onto the ceramic bracket. Lasing time required to keep the maximum intrapulpal temperature rise below 2 degrees C was determined by the use of thermocouples inserted into the pulp chambers of the specimens. A tensile debonding force was applied on the control group without lasing and the experimental group was debonded after applying a predetermined lasing time with a carbon dioxide laser. It was found that there was a significance difference (P < 0.05) in tensile debonding force between the control group and the experimental group. It is feasible to use a laser for the debonding of ceramic brackets while keeping the intrapulpal temperature rise below the threshold of pulpal damage.

Laser applications in the tracheobronchial tree.

PubMed

Rebeiz, E E; Shapsay, S M; Ingrams, D R

1996-12-01

This article outlines the historical development of the use of lasers in the tracheobronchial tree, the current indications for the use of carbon dioxide and neodymium:yttrium-aluminum-garnet lasers, and the management of complications. The merits of other laser wavelengths are mentioned, including use of the potassium titanyl phosphate laser in the pediatric airway. Photodynamic therapy is discussed, and some future developments are introduced.

Retrospective Analysis Of CO2 Laser Myringotomy

NASA Astrophysics Data System (ADS)

Lipman, Sidney P.; Guelcher, Robert T.

1988-06-01

A retrospective review of the author's series of 91 carbon dioxide (CO2) laser myringotomy cases performed between 1983 and 1986 is presented. Patients with chronic otitis media with effusion (COME) were selected on the basis of possible benefit from shorter ventilation time than tympanostomy tube insertion. The proceedings were performed on an outpatient basis with topical iontophoretic anesthesia, which offers significant cost savings and a lack of possible complications. The CO2 laser gives clean precise 0.8mm perforations which remain open for 2-4 weeks, this shorter ventilation time minimizing the period of water precautions and other side effects. The laser perforations heal well. With a success rate of 52 % reported, which could be increased with careful patient selection, we feel that the advantages of carbon dioxide laser myringotomy over myringotomy plus intubation outweight the risk of recurrent otitis media with effusion formation in those patients to whom this procedure is applicable.

The feasibility of TEA CO2 laser-induced plasma for spectrochemical analysis of geological samples in simulated Martian conditions

NASA Astrophysics Data System (ADS)

Savovic, Jelena; Stoiljkovic, Milovan; Kuzmanovic, Miroslav; Momcilovic, Milos; Ciganovic, Jovan; Rankovic, Dragan; Zivkovic, Sanja; Trtica, Milan

2016-04-01

The present work studies the possibility of using pulsed Transversely Excited Atmospheric (TEA) carbon dioxide laser as an energy source for laser-induced breakdown spectroscopy (LIBS) analysis of rocks under simulated Martian atmospheric conditions. Irradiation of a basaltic rock sample with the laser intensity of 56 MW cm- 2, in carbon-dioxide gas at a pressure of 9 mbar, created target plasma with favorable conditions for excitation of all elements usually found in geological samples. Detection limits of minor constituents (Ba, Cr, Cu, Mn, Ni, Sr, V, and Zr) were in the 3 ppm-30 ppm range depending on the element. The precision varied between 5% and 25% for concentration levels of 1% to 10 ppm, respectively. Generally, the proposed relatively simple TEA CO2 laser-LIBS system provides good sensitivity for geological studies under reduced CO2 pressure.

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.

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.

Applications of Kalman filtering to real-time trace gas concentration measurements

NASA Technical Reports Server (NTRS)

Leleux, D. P.; Claps, R.; Chen, W.; Tittel, F. K.; Harman, T. L.

2002-01-01

A Kalman filtering technique is applied to the simultaneous detection of NH3 and CO2 with a diode-laser-based sensor operating at 1.53 micrometers. This technique is developed for improving the sensitivity and precision of trace gas concentration levels based on direct overtone laser absorption spectroscopy in the presence of various sensor noise sources. Filter performance is demonstrated to be adaptive to real-time noise and data statistics. Additionally, filter operation is successfully performed with dynamic ranges differing by three orders of magnitude. Details of Kalman filter theory applied to the acquired spectroscopic data are discussed. The effectiveness of this technique is evaluated by performing NH3 and CO2 concentration measurements and utilizing it to monitor varying ammonia and carbon dioxide levels in a bioreactor for water reprocessing, located at the NASA-Johnson Space Center. Results indicate a sensitivity enhancement of six times, in terms of improved minimum detectable absorption by the gas sensor.

Optical Performance Of The Gemini Carbon Dioxide Laser Fusion System

NASA Astrophysics Data System (ADS)

Viswanathan, V. K.; Hayden, J. J.; Liberman, I.

1980-11-01

The performance of the Gemini two beam carbon dioxide laser fusion system was recently upgraded by installation of optical components with improved quality in the final amplifier. A theoretical analysis was conducted in conlunction with measurements of the new performance. The analysis and experimental procedures, and results obtained are reported and compared. Good agreement was found which was within the uncertainties of the analysis and the inaccuracies of the experiments. The focal spot Strehl ratio was between 0.24 and 0.3 for both beams.

Full-face carbon dioxide laser resurfacing: a 10-year follow-up descriptive study.

PubMed

Prado, Arturo; Andrades, Patricio; Danilla, Stefan; Benitez, Susana; Reyes, Sergio; Valenzuela, Gustavo; Guridi, Rodrigo; Fuentes, Patricio

2008-03-01

The purposes of this study were to retrospectively compare the 1-, 5-, and 10-year cosmetic outcomes of full-face carbon dioxide laser resurfacing using the SilkTouch technology, and analyze its advantages, disadvantages, and long-term results. Photographic results of full-face carbon dioxide laser resurfacing were evaluated after 1, 5, and 10 years. Statistical analysis considered surgeon and patient satisfaction based on a predetermined cosmetic visual analogue scale. Patients and two plastic surgeons unfamiliar with the cases evaluated objective postresurfacing results using Beausang's grading system and a modified wrinkle assessment scale. One hundred fifty-nine patients were treated and 46 patients completed 1-, 5-, and 10-year follow-up. Combined aesthetic procedures to the full-face carbon dioxide resurfacing were transcutaneous upper lid/lower lid transconjunctival blepharoplasty and endoscopic brow lifts in 15 patients. After 1 year, some relapse occurred, but the overall aesthetic result remained very good. At 5 and 10 years, respectively, 32 and 20 percent of the sample maintained good-quality skin texture; 22 and 19 percent achieved correction of skin pigmentation without scars; and 88 and 98 percent needed correction of recurrent rhytides, jowling, and redundant skin. Permanent hypopigmentation was found in four cases (8.7 percent). The authors' early experience with the carbon dioxide laser was excellent, but after 1 year, they noticed lines of demarcation between treated and nontreated skin or persistent erythema. After 5 and 10 years, advantages were maintenance of good skin texture, ablation of fine wrinkles, and long-term correction of skin pigmentation. Disadvantages included permanent hypopigmentation of the mandible-neck junction, telangiectasia, and possible accentuation of skin redundancy.

Efficient, space-based, PM 100W thulium fiber laser for pumping Q-switched 2μm Ho:YLF for global winds and carbon dioxide lidar

NASA Astrophysics Data System (ADS)

Engin, Doruk; Mathason, Brian; Storm, Mark

2017-08-01

Global wind measurements are critically needed to improve and extend NOAA weather forecasting that impacts U.S. economic activity such as agriculture crop production, as well as hurricane forecasting, flooding, and FEMA disaster planning.1 NASA and the 2007 National Research Council (NRC) Earth Science Decadal Study have also identified global wind measurements as critical for global change research. NASA has conducted aircraft-based wind lidar measurements using 2 um Ho:YLF lasers, which has shown that robust wind measurements can be made. Fibertek designed and demonstrated a high-efficiency, 100 W average power continuous wave (CW) 1940 nm thulium (Tm)- doped fiber laser bread-board system meeting all requirements for a NASA Earth Science spaceflight 2 μm Ho:YLF pump laser. Our preliminary design shows that it is possible to package the laser for high-reliability spaceflight operation in an ultra-compact 2″x8″x14″ size and weight <8.5 lbs. A spaceflight 100 W polarization maintaining (PM) Tm laser provides a path to space for a pulsed, Q-switched 2 μm Ho:YLF laser with 30-80 mJ/pulse range at 100-200 Hz repletion rates.

Gas sensing using wavelength modulation spectroscopy

NASA Astrophysics Data System (ADS)

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

2014-08-01

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

Development of an Eye-Safe Micro-Pulse Differential Absorption Lidar (DIAL) for Carbon Dioxide Profilings

NASA Astrophysics Data System (ADS)

Johnson, W.; Repasky, K. S.; Nehrir, A. R.; Carlsten, J.

2011-12-01

A differential absorption lidar (DIAL) for monitoring carbon dioxide (CO2) is under development at Montana State University using commercially available parts. Two distributed feedback (DFB) lasers, one at the on-line wavelength and one at the off-line wavelength are used to injection seed a fiber amplifier. The DIAL operates in the 1.57 micron carbon dioxide absorption band at an on-line wavelength of 1.5714060 microns. The laser transmitter produces 40 μJ pulses with a pulse duration of 1 μs and a pulse repetition frequency of 20 kHz. The scattered light from the laser transmitter is collected using a 28 cm diameter Schmidt-Cassegrain telescope. The light collected by the telescope is collimated and then filtered using a 0.8 nm FWHM narrowband interference filter. After the optical filter, the light is coupled into a multimode optical fiber with a 1000 μm core diameter. The output from the optical fiber is coupled into a photomultiplier tube (PMT) used to monitor the return signal. The analog output from the PMT is next incident on a discriminator producing TTL logic pulses for photon counting. The output from the PMT and discriminator is monitored using a multichannel scalar card allowing the counting of the TTL pulses as a function of range. Data from the DIAL instrument is collected in the following manner. The fiber amplifier is injection seeded first with the on-line DFB laser. The return signal as a function of range is integrated using the multichannel scalar for a user defined time, typically set at 6 s. The off-line DFB laser is then used to injection seed the fiber amplifier and the process is repeated. This process is repeated for a user defined period. The CO2 concentration as a function of range is calculated using the on-line and off-line return signals with the DIAL equation. A comparison of the CO2 concentration measured using the DIAL instrument at 1.5 km and a Li-Cor LI-820 in situ sensor located at 1.5 km from the DIAL over a 2.5 hour period indicate that the CO2 DIAL has an accuracy of ±20 parts per million (PPM).

Surgical Coagulator With Carbon Dioxide Laser For Gynecology

NASA Astrophysics Data System (ADS)

Wolinski, Wieslaw; Kazmirowski, Antoni; Korobowicz, Witold; Olborski, Zbigniew

1987-10-01

The technical data and parameters of the CO2 surgical laser for gynecology are given. Coagulator was designed and constructed in Institute of Microelectronics and Optoelectronics Warsaw Technical University.

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.

[In-transit metastasis in melanoma: Efficacy of topical imiquimod combined with carbon dioxide laser or with electrocautery].

PubMed

Elfatoiki, F-Z; Longvert, C; Clerici, T; Bourgault-Villada, I; Roudier-Pujol, C; Vasseur, E; Saiag, P

2014-02-01

In-transit metastases in cutaneous melanoma are common and difficult to manage. Therapy is mainly palliative. Use of topical imiquimod has been assessed for surface metastases. We report on four patients with cutaneous melanoma metastases treated with topical imiquimod associated with carbon dioxide laser in the first two patients and with electrocoagulation in the two others. For two patients, we noted complete regression of the lesions after 15 and 18 months. For the two others, treatment was stopped after 9 to 10 months because of progression of subcutaneous metastasis and distant metastasis. Topical imiquimod is an alternative treatment used in superficial in-transit metastasis of melanoma. Its use as a monotherapy is sometimes ineffective. We elected to use combined pre-treatment with carbon dioxide laser or electrocoagulation in order to potentiate the action of imiquimod. This simple and inexpensive therapeutic strategy constitutes a palliative treatment that can allow prolonged local control of cutaneous metastasis. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Backscatter and extinction measurements in cloud and drizzle at CO2 laser wavelengths

NASA Technical Reports Server (NTRS)

Jennings, S. G.

1986-01-01

The backscatter and extinction of laboratory generated cloud and drizzle sized water drops were measured at carbon dioxide laser wavelengths (predominately at lambda = 10.591 micrometers). Two distinctly different drop size regimes were studied: one which covers the range normally encompassed by natural cloud droplets and the other representative of mist or drizzle sized drops. The derivation and verification of the relation between extinction and backscatter at carbon dioxide laser wavelengths should allow the determination of large cloud drop and drizzle extinction coefficient solely from a lidar return signal without requiring knowledge of the drop size distribution. This result will also apply to precipitation sized drops so long as they are spherical.

Advances in Fabry-Perot and tunable quantum cascade lasers

NASA Astrophysics Data System (ADS)

Patel, C. Kumar N.

2017-05-01

Quantum cascade lasers (QCLs) are becoming mature infrared emitting devices that convert electrical power directly into optical power and generate laser radiation in the mid wave infrared (MWIR) and long wave infrared (LWIR) regions. These lasers operate at room temperature in the 3.5 μm to >12.0 μm region. QCLs operate at longer wavelengths into the terahertz region; however, these require some level of cryogenic cooling. Nonetheless, QCLs are the only solid-state sources that convert electrical power into optical power directly in these spectral regions. Three critical advances have contributed to the broad range of applications of QCLs, since their first demonstration in 1994 [1]. The first of these was the utilization of two phonon resonance for deexcitation of electrons from the lower lasing level [2]; the second is the utilization of epi-down mounting with hard solder of QCLs for practical applications [3]; and the third is the invention of nonresonant extraction for deexciting electrons from the lower laser level and simultaneously removing constraints on QCL structure design for extending high power room temperature operation to a broad range of wavelengths [4]. Although QCLs generate CW radiation at room temperature at wavelengths ranging from 3.5 μm to <12.0 μm, two spectral regions are very important for a broad range of applications. These are the first and the second atmospheric transmission windows from 3.5 μm to 5.0 μm and from 8.0 μm to 12.0 μm, respectively. Both of these windows (except for the spectral region near 4.2 μm, which is dominated by the infrared absorption from atmospheric carbon dioxide) are relatively free from atmospheric absorption and have a range of applications that involve long distance propagation.

Influence of instrument conditions on the evaporation behavior of uranium dioxide with UV laser-assisted atom probe tomography

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

Valderrama, B.; Henderson, H.B.; Gan, J.

2015-04-01

Atom probe tomography (APT) provides the ability to detect subnanometer chemical variations spatially, with high accuracy. However, it is known that compositional accuracy can be affected by experimental conditions. A study of the effect of laser energy, specimen base temperature, and detection rate is performed on the evaporation behavior of uranium dioxide (UO 2). In laser-assisted mode, tip geometry and standing voltage also contribute to the evaporation behavior. In this investigation, it was determined that modifying the detection rate and temperature did not affect the evaporation behavior as significantly as laser energy. It was also determined that three laser evaporationmore » regimes are present in UO 2. Very low laser energy produces a behavior similar to DC-field evaporation, moderate laser energy produces the desired laser-assisted field evaporation characteristic and high laser energy induces thermal effects, negatively altering the evaporation behavior. The need for UO 2 to be analyzed under moderate laser energies to produce accurate stoichiometry distinguishes it from other oxides. The following experimental conditions providing the best combination of mass resolving power, accurate stoichiometry, and uniform evaporation behavior: 50 K, 10 pJ laser energy, a detection rate of 0.003 atoms per pulse, and a 100 kHz repetition rate.« less

Efficiency of Carbon Dioxide Fractional Laser in Skin Resurfacing.

PubMed

Petrov, Andrej

2016-06-15

The aim of the study was to confirm the efficiency and safety of the fractional CO2 laser in skin renewal and to check the possibility of having a synergistic effect in patients who besides carbon dioxide laser are treated with PRP (platelet-rich plasma) too. The first group (Examined Group 1 or EG1) included 107 patients treated with fractional CO2 laser (Lutronic eCO2) as mono-therapy. The second group (Control Group or CG) covered 100 patients treated with neither laser nor plasma in the same period but subjected to local therapy with drugs or other physio-procedures under the existing protocols for treatment of certain diseases. The third group (Examined Group 2 or EG2) treated 25 patients with combined therapy of CO2 laser and PRP in the treatment of facial rejuvenation or treatment of acne scars. Patient's satisfaction, in general, is significantly greater in both examined groups (EG1 and EG2) (p < 0.001). It was found the significant difference between control and examined group from the treatment in acne scar (Fisher exact two tailed p < 0.001). Patients satisfaction with the treatment effect in rejuvenation of the skin is significant (χ2 = 39.41; df = 4; p < 0.001). But, patients satisfaction from the treatment with HPV on the skin was significantly lower in examined group (treated with laser), p = 0.0002. Multifunctional fractional carbon dioxide laser used in treatment of patients with acne and pigmentation from acne, as well as in the treatment of scars from different backgrounds, is an effective and safe method that causes statistically significant better effect of the treatment, greater patients' satisfaction, minimal side effects and statistically better response to the therapy, according to assessments by the patient and the therapist.

Room-temperature subnanosecond waveguide lasers in Nd:YVO4 Q-switched by phase-change VO2: A comparison with 2D materials

NASA Astrophysics Data System (ADS)

Nie, Weijie; Li, Rang; Cheng, Chen; Chen, Yanxue; Lu, Qingming; Romero, Carolina; Vázquez de Aldana, Javier R.; Hao, Xiaotao; Chen, Feng

2017-04-01

We report on room-temperature subnanosecond waveguide laser operation at 1064 nm in a Nd:YVO4 crystal waveguide through Q-switching of phase-change nanomaterial vanadium dioxide (VO2). The unique feature of VO2 nanomaterial from the insulating to metallic phases offers low-saturation-intensity nonlinear absorptions of light for subnanosecond pulse generation. The low-loss waveguide is fabricated by using the femtosecond laser writing with depressed cladding geometry. Under optical pump at 808 nm, efficient pulsed laser has been achieved in the Nd:YVO4 waveguide, reaching minimum pulse duration of 690 ps and maximum output average power of 66.7 mW. To compare the Q-switched laser performances by VO2 saturable absorber with those based on two-dimensional materials, the 1064-nm laser pulses have been realized in the same waveguide platform with either graphene or transition metal dichalcogenide (in this work, WS2) coated mirror. The results on 2D material Q-switched waveguide lasers have shown that the shortest pulses are with 22-ns duration, whilst the maximum output average powers reach ~161.9 mW. This work shows the obvious difference on the lasing properties based on phase-change material and 2D materials, and suggests potential applications of VO2 as low-cost saturable absorber for subnanosecond laser generation.

Room-temperature subnanosecond waveguide lasers in Nd:YVO4 Q-switched by phase-change VO2: A comparison with 2D materials.

PubMed

Nie, Weijie; Li, Rang; Cheng, Chen; Chen, Yanxue; Lu, Qingming; Romero, Carolina; Vázquez de Aldana, Javier R; Hao, Xiaotao; Chen, Feng

2017-04-06

We report on room-temperature subnanosecond waveguide laser operation at 1064 nm in a Nd:YVO 4 crystal waveguide through Q-switching of phase-change nanomaterial vanadium dioxide (VO 2 ). The unique feature of VO 2 nanomaterial from the insulating to metallic phases offers low-saturation-intensity nonlinear absorptions of light for subnanosecond pulse generation. The low-loss waveguide is fabricated by using the femtosecond laser writing with depressed cladding geometry. Under optical pump at 808 nm, efficient pulsed laser has been achieved in the Nd:YVO 4 waveguide, reaching minimum pulse duration of 690 ps and maximum output average power of 66.7 mW. To compare the Q-switched laser performances by VO 2 saturable absorber with those based on two-dimensional materials, the 1064-nm laser pulses have been realized in the same waveguide platform with either graphene or transition metal dichalcogenide (in this work, WS 2 ) coated mirror. The results on 2D material Q-switched waveguide lasers have shown that the shortest pulses are with 22-ns duration, whilst the maximum output average powers reach ~161.9 mW. This work shows the obvious difference on the lasing properties based on phase-change material and 2D materials, and suggests potential applications of VO 2 as low-cost saturable absorber for subnanosecond laser generation.

The CO2 laser frequency stability measurements

NASA Technical Reports Server (NTRS)

Johnson, E. H., Jr.

1973-01-01

Carbon dioxide laser frequency stability data are considered for a receiver design that relates to maximum Doppler frequency and its rate of change. Results show that an adequate margin exists in terms of data acquisition, Doppler tracking, and bit error rate as they relate to laser stability and transmitter power.

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.

Hydrazine Detection with a Tunable Diode Laser Spectrometer

NASA Technical Reports Server (NTRS)

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

1999-01-01

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

Measurement of Carbon Dioxide Column via Space Borne Laser Absorption

NASA Technical Reports Server (NTRS)

Heaps, WIlliam S.

2007-01-01

In order to better understand the budget of carbon dioxide in the Earth's atmosphere it is necessary to develop a global high precision understanding of the carbon dioxide column. In order to uncover the 'missing sink that is responsible for the large discrepancies in the budget as we presently understand it calculation has indicated that measurement accuracy on the order of 1 ppm is necessary. Because typical column average CO2 has now reached 380 ppm this represents a precision on the order of .25% for these column measurements. No species has ever been measured from space at such a precision. In recognition of the importance of understanding the CO2 budget in order to evaluate its impact on global warming the National Research Council in its decadal survey report to NASA recommended planning for a laser based total CO2 mapping mission in the near future. The extreme measurement accuracy requirements on this mission places very strong requirements on the laser system used for the measurement. This work presents an analysis of the characteristics necessary in a laser system used to make this measurement. Consideration is given to the temperature dependence, pressure broadening, and pressure shift of the CO2 lines themselves and how these impact the laser system characteristics Several systems for meeting these requirements that are under investigation at various institutions in the US as well as Europe will be discussed.

CO2 laser arthroscopy-through the arthroscope

NASA Astrophysics Data System (ADS)

Garrick, James G.

1990-06-01

Orthopedists have been among the last of the specialists to utilize lasers in surgery. Even today, laser usage in orthopedics is almost exclusively limited to arthroscopy procedures. Although other types of lasers have been approved for use in orthopedics, nearly all laser-assisted arthroscopic procedures have involved the carbon dioxide laser in the knee. These techniques involve skills and problems not previously encountered. In an attempt to simplify the usage and circumvent some of the problems, we describe a means of laser energy delivery through the arthroscope.

Characterizing Far-infrared Laser Emissions and the Measurement of Their Frequencies.

PubMed

Jackson, Michael; Zink, Lyndon R

2015-12-18

The generation and subsequent measurement of far-infrared radiation has found numerous applications in high-resolution spectroscopy, radio astronomy, and Terahertz imaging. For about 45 years, the generation of coherent, far-infrared radiation has been accomplished using the optically pumped molecular laser. Once far-infrared laser radiation is detected, the frequencies of these laser emissions are measured using a three-laser heterodyne technique. With this technique, the unknown frequency from the optically pumped molecular laser is mixed with the difference frequency between two stabilized, infrared reference frequencies. These reference frequencies are generated by independent carbon dioxide lasers, each stabilized using the fluorescence signal from an external, low pressure reference cell. The resulting beat between the known and unknown laser frequencies is monitored by a metal-insulator-metal point contact diode detector whose output is observed on a spectrum analyzer. The beat frequency between these laser emissions is subsequently measured and combined with the known reference frequencies to extrapolate the unknown far-infrared laser frequency. The resulting one-sigma fractional uncertainty for laser frequencies measured with this technique is ± 5 parts in 10(7). Accurately determining the frequency of far-infrared laser emissions is critical as they are often used as a reference for other measurements, as in the high-resolution spectroscopic investigations of free radicals using laser magnetic resonance. As part of this investigation, difluoromethane, CH2F2, was used as the far-infrared laser medium. In all, eight far-infrared laser frequencies were measured for the first time with frequencies ranging from 0.359 to 1.273 THz. Three of these laser emissions were discovered during this investigation and are reported with their optimal operating pressure, polarization with respect to the CO2 pump laser, and strength.

Characterizing Far-infrared Laser Emissions and the Measurement of Their Frequencies

PubMed Central

Jackson, Michael; Zink, Lyndon R.

2015-01-01

The generation and subsequent measurement of far-infrared radiation has found numerous applications in high-resolution spectroscopy, radio astronomy, and Terahertz imaging. For about 45 years, the generation of coherent, far-infrared radiation has been accomplished using the optically pumped molecular laser. Once far-infrared laser radiation is detected, the frequencies of these laser emissions are measured using a three-laser heterodyne technique. With this technique, the unknown frequency from the optically pumped molecular laser is mixed with the difference frequency between two stabilized, infrared reference frequencies. These reference frequencies are generated by independent carbon dioxide lasers, each stabilized using the fluorescence signal from an external, low pressure reference cell. The resulting beat between the known and unknown laser frequencies is monitored by a metal-insulator-metal point contact diode detector whose output is observed on a spectrum analyzer. The beat frequency between these laser emissions is subsequently measured and combined with the known reference frequencies to extrapolate the unknown far-infrared laser frequency. The resulting one-sigma fractional uncertainty for laser frequencies measured with this technique is ± 5 parts in 107. Accurately determining the frequency of far-infrared laser emissions is critical as they are often used as a reference for other measurements, as in the high-resolution spectroscopic investigations of free radicals using laser magnetic resonance. As part of this investigation, difluoromethane, CH2F2, was used as the far-infrared laser medium. In all, eight far-infrared laser frequencies were measured for the first time with frequencies ranging from 0.359 to 1.273 THz. Three of these laser emissions were discovered during this investigation and are reported with their optimal operating pressure, polarization with respect to the CO2 pump laser, and strength. PMID:26709957

Technology advancement for the ASCENDS mission using the ASCENDS CarbonHawk Experiment Simulator (ACES)

NASA Astrophysics Data System (ADS)

Obland, M. D.; Antill, C.; Browell, E. V.; Campbell, J. F.; CHEN, S.; Cleckner, C.; Dijoseph, M. S.; Harrison, F. W.; Ismail, S.; Lin, B.; Meadows, B. L.; Mills, C.; Nehrir, A. R.; Notari, A.; Prasad, N. S.; Kooi, S. A.; Vitullo, N.; Dobler, J. T.; Bender, J.; Blume, N.; Braun, M.; Horney, S.; McGregor, D.; Neal, M.; Shure, M.; Zaccheo, T.; Moore, B.; Crowell, S.; Rayner, P. J.; Welch, W.

2013-12-01

The ASCENDS CarbonHawk Experiment Simulator (ACES) is a NASA Langley Research Center project funded by NASA's Earth Science Technology Office that seeks to advance technologies critical to measuring atmospheric column carbon dioxide (CO2) mixing ratios in support of the NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission. The technologies being advanced are: (1) multiple transmitter and telescope-aperture operations, (2) high-efficiency CO2 laser transmitters, (3) a high bandwidth detector and transimpedance amplifier (TIA), and (4) advanced algorithms for cloud and aerosol discrimination. The instrument architecture is being developed for ACES to operate on a high-altitude aircraft, and it will be directly scalable to meet the ASCENDS mission requirements. The above technologies are critical for developing an airborne simulator and spaceborne instrument with lower platform consumption of size, mass, and power, and with improved performance. This design employs several laser transmitters and telescope-apertures to demonstrate column CO2 retrievals with alignment of multiple laser beams in the far-field. ACES will transmit five laser beams: three from commercial lasers operating near 1.57-microns, and two from the Exelis atmospheric oxygen (O2) fiber laser amplifier system operating near 1.26-microns. The Master Oscillator Power Amplifier at 1.57-microns measures CO2 column concentrations using an Integrated-Path Differential Absorption (IPDA) lidar approach. O2 column amounts needed for calculating the CO2 mixing ratio will be retrieved using the Exelis laser system with a similar IPDA approach. The three aperture telescope design was built to meet the constraints of the Global Hawk high-altitude unmanned aerial vehicle (UAV). This assembly integrates fiber-coupled transmit collimators for all of the laser transmitters and fiber-coupled optical signals from the three telescopes to the aft optics and detector package. The detector/TIA effort has improved the existing detector subsystem by: increasing its bandwidth to 5.4 MHz, exceeding the original goal of 5 MHz; reducing the overall mass from 18 lbs to <10 lbs; and increasing the duration of autonomous, service-free operation periods from 4 hrs to >24 hrs. The new detector subsystem will permit higher laser modulation rates, which provides greater flexibility for implementing thin-cloud discrimination algorithms as well as improving range resolution and error reduction, and will enable long-range flights on the Global Hawk. The cloud/aerosol discrimination work features development of new algorithms by Langley and Exelis for the avoidance of bias errors in the retrieval of column CO2 induced by the presence of thin clouds.

Ablative Fractional 10 600 nm Carbon Dioxide Laser Versus Non-ablative Fractional 1540 nm Erbium-Glass Laser in Egyptian Post-acne Scar patients.

PubMed

Elsaie, Mohamed L; Ibrahim, Shady M; Saudi, Wael

2018-01-01

Introduction: Non-ablative fractional erbium-doped glass 1540 nm and fractional ablative 10600 nm carbon dioxide lasers are regarded as effective modalities for treating acne atrophic scars. In this study, we aimed to compare the effectiveness of fractional CO 2 laser and fractional nonablative 1540 nm erbium doped glass laser in treating post acne atrophic scars in Egyptian patients. Methods: Fifty-eight patients complaining of moderate and severe acne atrophic scars were randomly divided into 2 groups of 29 patients each. Both groups were subjected to 4 treatment sessions with 3 weeks interval and were followed up for 3 months. In group A, enrolled patient sreceived C2 laser, while in group B, patients were treated with 1540 nm erbium glass fractional laser. Results: Clinical assessment revealed that the mean grades of progress and improvement were higher with fractional 10600 nm CO2 laser but with non-significant difference between both treatments ( P = 0.1). The overall patients' satisfaction with both lasers were not significantly different ( P = 0.44). Conclusion: Both fractional ablative CO2 and fractional non-ablative erbium glass lasers are good modalities for treating acne scars with a high efficacy and safety profile and good patient satisfaction. The fractional ablative laser showed higher efficacy while non-ablative laser offered less pain and shorter downtime.

Laser Resurfacing Pearls

PubMed Central

Shah, Sonia; Alam, Murad

2012-01-01

Ablative skin resurfacing using the carbon dioxide laser was long considered the gold standard for treatment of photoaging, acne scars, and rhytids. However, conventional full-face carbon dioxide resurfacing is associated with significant risk of side effects and a prolonged postoperative recovery period. Fractional resurfacing has recently revolutionized laser surgery by offering close to comparable results with minimal side effects and a more rapid recovery. Although fractional devices have grown in popularity, and have essentially replaced traditional resurfacing, fractional resurfacing can still be a challenging modality to control precisely due to hardware variations across comparable devices, the range of settings that can be used, and patient-specific considerations. Certain precautions and rules of thumb can reduce the risk associated with fractional resurfacing, and increase the likelihood of a good outcome. PMID:23904821

Laser resurfacing pearls.

PubMed

Shah, Sonia; Alam, Murad

2012-08-01

Ablative skin resurfacing using the carbon dioxide laser was long considered the gold standard for treatment of photoaging, acne scars, and rhytids. However, conventional full-face carbon dioxide resurfacing is associated with significant risk of side effects and a prolonged postoperative recovery period. Fractional resurfacing has recently revolutionized laser surgery by offering close to comparable results with minimal side effects and a more rapid recovery. Although fractional devices have grown in popularity, and have essentially replaced traditional resurfacing, fractional resurfacing can still be a challenging modality to control precisely due to hardware variations across comparable devices, the range of settings that can be used, and patient-specific considerations. Certain precautions and rules of thumb can reduce the risk associated with fractional resurfacing, and increase the likelihood of a good outcome.

Laser removal of loose uranium compound contamination from metal surfaces

NASA Astrophysics Data System (ADS)

Roberts, D. E.; Modise, T. S.

2007-04-01

Pulsed laser removal of surface contamination of uranyl nitrate and uranium dioxide from stainless steel has been studied. Most of the loosely bound contamination has been removed at fluence levels below 0.5 J cm -2, leaving about 5% fixed contamination for uranyl nitrate and 15% for uranium dioxide. Both alpha and beta activities are then sufficiently low that contaminated objects can be taken out of a restricted radiation area for re-use. The ratio of beta to alpha activity is found to be a function of particle size and changes during laser removal. In a separate experiment using technetium-99m, the collection of removed radioactivity in the filter was studied and an inventory made of removed and collected contamination.

Carbon dioxide UV laser-induced fluorescence in high-pressure flames

NASA Astrophysics Data System (ADS)

Bessler, W. G.; Schulz, C.; Lee, T.; Jeffries, J. B.; Hanson, R. K.

2003-07-01

Laser-induced fluorescence (LIF) of carbon dioxide is investigated with excitation between 215 and 255 nm with spectrally resolved detection in 5-40 bar premixed CH 4/O 2/Ar and CH 4/air flat-flames at fuel/air ratios between 0.8 and 1.9. The LIF signal consists of a broad (200-450 nm) continuum with a faint superimposed structure, and this signal is absent in similar H 2/O 2/Ar flames. There is strong evidence this signal arises from CO 2, as the signal variations with excitation wavelength, equivalence ratio and flame temperature all correlate with CO 2 absorption cross-sections. The signal is linear with pressure and laser fluence within the investigated ranges.

Saline soaked pledgets prevent carbon dioxide laser-induced endotracheal tube cuff ignition.

PubMed

Sosis, M B

1995-08-01

To determine whether saline soaked pledgets would protect the cuffs of polyvinylchloride (PVC) endotracheal tubes from carbon dioxide (CO2) laser-induced combustion. 12 PVC endotracheal tubes were studied. The cuffed end of each was placed in a graduated cylinder and flushed with 5 L/min of oxygen for 5 minutes. The endotracheal tube's cuff was then inflated with air and the system pressure set to 20 cm H2O. Research laboratory of a university hospital. Six of the endotracheal tube cuffs were protected with 1 inch by 3 inch saline soaked pledgets and six were left unprotected. A CO2 laser set to 40 watts was then fired at the cuffs. All six unprotected cuffs were ignited in less than 1 second. No significant combustion occurred at the six pledget protected endotracheal tube cuffs after 1 minute of laser fire. Under the conditions of this experiment, saline soaked pledgets protected PVC endotracheal tube cuffs from the CO2 laser.

Laser welding of fused quartz

DOEpatents

Piltch, Martin S.; Carpenter, Robert W.; Archer, III, McIlwaine

2003-06-10

Refractory materials, such as fused quartz plates and rods are welded using a heat source, such as a high power continuous wave carbon dioxide laser. The radiation is optimized through a process of varying the power, the focus, and the feed rates of the laser such that full penetration welds may be accomplished. The process of optimization varies the characteristic wavelengths of the laser until the radiation is almost completely absorbed by the refractory material, thereby leading to a very rapid heating of the material to the melting point. This optimization naturally occurs when a carbon dioxide laser is used to weld quartz. As such this method of quartz welding creates a minimum sized heat-affected zone. Furthermore, the welding apparatus and process requires a ventilation system to carry away the silicon oxides that are produced during the welding process to avoid the deposition of the silicon oxides on the surface of the quartz plates or the contamination of the welds with the silicon oxides.

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.

Co2 Laser Resurfacing for Facial Rhytides

PubMed Central

Jain, Vinod K; Ghiya, B C; Gupta, Dhruv; Singhi, Mahendra K

2008-01-01

Resurfacing of facial rhytides (periorbital crow-feet wrinkles) was performed in three cases by carbon dioxide laser (Sharplan® 1030 machine). Good to excellent results were observed. However, erythema and postinflammatory pigmentation were important side effects. PMID:20300334

Optical communication in free space

NASA Technical Reports Server (NTRS)

Plotkin, H. H.; Mcavoy, N.; Fitzmaurice, M. W.

1974-01-01

Two classes of laser communication systems for handling very high data rates across inter-satellite distances are considered that provide for high antenna gains, wide modulation bandwidths, and optical receiver sensitivities. System design considerations are based upon the carbon dioxide laser modulation to accommodate digital or analog information, and the neodymium doped YAG laser pulse for digital modulation.

Study on ceramic coating on the enamel surface using a carbon dioxide laser.

PubMed

Nihei, Tomotaro; Kurata, Shigeaki; Ohashi, Katsura; Umemoto, Kozo; Teranaka, Toshio

2011-01-01

The aims of this study were to evaluate a new restorative method using a carbon dioxide laser (CO(2)-laser) and to evaluate the acid resistance of teeth. Experimental calcium phosphate glass (CPG) powder and two low melting point ceramics (Finesse and zirconium silicate) were fused to enamel surfaces using a CO(2)-laser at an irradiation intensity of 1.0 watt for 30 seconds with a beam size of 0.49 mm at the focal point. The treated teeth were observed with a scanning electron microscope, and the acid resistance of the treated enamel surfaces was evaluated. The CPG fused successfully to the enamel surface, and the treated enamel surface showed high acid resistance compared with the low melting point ceramics and the non-irradiated surfaces. This system may lead to the development of new restorative methods that do not require the use of bonding agents.

Optical design of laser transmission system

NASA Astrophysics Data System (ADS)

Zhang, Yulan; Feng, Jinliang; Li, Yongliang; Yang, Jiandong

1998-08-01

This paper discusses a design of optical transfer system used in carbon-dioxide laser therapeutic machine. The design of this system is according to the requirement of the therapeutic machine. The therapeutic machine requires the movement of laser transfer system is similar to the movement of human beings arms, which possesses 7 rotating hinges. We use optical hinges, which is composed of 45 degree mirrors. Because the carbon-dioxide laser mode is not good, light beam diameter at focus and divergence angle dissemination are big, we use a collecting lens at the transfer system output part in order to make the light beam diameter at focus in 0.2 to approximately 0.3 mm. For whole system the focus off-axis error is less than 0.5 mm, the transfer power consumption is smaller than 10%. The system can move in three dimension space freely and satisfies the therapeutic machine requirement.

Fractional carbon dioxide laser versus low-dose UVA-1 phototherapy for treatment of localized scleroderma: a clinical and immunohistochemical randomized controlled study.

PubMed

Shalaby, S M; Bosseila, M; Fawzy, M M; Abdel Halim, D M; Sayed, S S; Allam, R S H M

2016-11-01

Morphea is a rare fibrosing skin disorder that occurs as a result of abnormal homogenized collagen synthesis. Fractional ablative laser resurfacing has been used effectively in scar treatment via abnormal collagen degradation and induction of healthy collagen synthesis. Therefore, fractional ablative laser can provide an effective modality in treatment of morphea. The study aimed at evaluating the efficacy of fractional carbon dioxide laser as a new modality for the treatment of localized scleroderma and to compare its results with the well-established method of UVA-1 phototherapy. Seventeen patients with plaque and linear morphea were included in this parallel intra-individual comparative randomized controlled clinical trial. Each with two comparable morphea lesions that were randomly assigned to either 30 sessions of low-dose (30 J/cm 2 ) UVA-1 phototherapy (340-400 nm) or 3 sessions of fractional CO 2 laser (10,600 nm-power 25 W). The response to therapy was then evaluated clinically and histopathologically via validated scoring systems. Immunohistochemical analysis of TGF-ß1 and MMP1 was done. Patient satisfaction was also assessed. Wilcoxon signed rank test for paired (matched) samples and Spearman rank correlation equation were used as indicated. Comparing the two groups, there was an obvious improvement with fractional CO 2 laser that was superior to that of low-dose UVA-1 phototherapy. Statistically, there was a significant difference in the clinical scores (p = 0.001), collagen homogenization scores (p = 0.012), and patient satisfaction scores (p = 0.001). In conclusion, fractional carbon dioxide laser is a promising treatment modality for cases of localized morphea, with proved efficacy of this treatment on clinical and histopathological levels.

The Effect of Neodymium: Yttrium Aluminum Garnet and Fractional Carbon Dioxide Lasers on Alopecia Areata: A Prospective Controlled Clinical Trial.

PubMed

Yalici-Armagan, Basak; Elcin, Gonca

2016-04-01

Effective treatment options for alopecia areata (AA) are missing. Whether lasers might be effective is a topic of debate. We aimed to evaluate whether neodymium: yttrium aluminum garnet (Nd:YAG) or fractional carbon dioxide lasers might stimulate the development of new hair. Thirty-two patients who had long-standing and treatment refractory diseases were recruited for the study. Three different patches on the scalp were selected, 1 of which served as control. The mean outcome measure was the hair count, which was calculated with the digital phototrichogram. Response was defined as at least 25% increase in the mean hair count at the treated patch compared with the control patch. At the end of the study, there was no statistically significant difference in the mean hair count for the 3 patches. In 7 of 32 patients (22%), an increase in the mean hair count was observed on the whole scalp including the control patch, which resulted in an improved Severity of Alopecia Tool (SALT) score. We have observed that Nd:YAG or fractional carbon dioxide lasers did not increase the mean hair count on the treated AA patches when compared with the control patch. However, an SALT score improvement in 22% of the patients suggested spontaneous remission.

Monolithic photonic integration technology platform and devices at wavelengths beyond 2μm for gas spectroscopy applications

NASA Astrophysics Data System (ADS)

Latkowski, S.; van Veldhoven, P. J.; Hänsel, A.; D'Agostino, D.; Rabbani-Haghighi, H.; Docter, B.; Bhattacharya, N.; Thijs, P. J. A.; Ambrosius, H. P. M. M.; Smit, M. K.; Williams, K. A.; Bente, E. A. J. M.

2017-02-01

In this paper a generic monolithic photonic integration technology platform and tunable laser devices for gas sensing applications at 2 μm will be presented. The basic set of long wavelength optical functions which is fundamental for a generic photonic integration approach is realized using planar, but-joint, active-passive integration on indium phosphide substrate with active components based on strained InGaAs quantum wells. Using this limited set of basic building blocks a novel geometry, widely tunable laser source was designed and fabricated within the first long wavelength multiproject wafer run. The fabricated laser operates around 2027 nm, covers a record tuning range of 31 nm and is successfully employed in absorption measurements of carbon dioxide. These results demonstrate a fully functional long wavelength photonic integrated circuit that operates at these wavelengths. Moreover, the process steps and material system used for the long wavelength technology are almost identical to the ones which are used in the technology process at 1.5μm which makes it straightforward and hassle-free to transfer to the photonic foundries with existing fabrication lines. The changes from the 1550 nm technology and the trade-offs made in the building block design and layer stack will be discussed.

Advances in High Energy Solid-State 2-micron Laser Transmitter Development for Ground and Airborne Wind and CO2 Measurements

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta; Chen, Songsheng; Kavaya, Michael J.; Trieu, Bo; Bai, Yingxin; Petzar, Paul; Modlin, Edward A.; Koch, Grady;

Long-range open-path greenhouse gas monitoring using mid-infrared laser dispersion spectroscopy

NASA Astrophysics Data System (ADS)

Daghestani, Nart; Brownsword, Richard; Weidmann, Damien

2015-04-01

Accurate and sensitive methods of monitoring greenhouse gas (GHG) emission over large areas has become a pressing need to deliver improved estimates of both human-made and natural GHG budgets. These needs relate to a variety of sectors including environmental monitoring, energy, oil and gas industry, waste management, biogenic emission characterization, and leak detection. To address the needs, long-distance open-path laser spectroscopy methods offer significant advantages in terms of temporal resolution, sensitivity, compactness and cost effectiveness. Path-integrated mixing ratio measurements stemming from long open-path laser spectrometers can provide emission mapping when combined with meteorological data and/or through tomographic approaches. Laser absorption spectroscopy is the predominant method of detecting gasses over long integrated path lengths. The development of dispersion spectrometers measuring tiny refractive index changes, rather than optical power transmission, may offer a set of specific advantages1. These include greater immunity to laser power fluctuations, greater dynamic range due to the linearity of dispersion, and ideally a zero baseline signal easing quantitative retrievals of path integrated mixing ratios. Chirped laser dispersion spectrometers (CLaDS) developed for the monitoring of atmospheric methane and carbon dioxide will be presented. Using quantum cascade laser as the source, a minimalistic and compact system operating at 7.8 μm has been developed and demonstrated for the monitoring of atmospheric methane over a 90 meter open path2. Through full instrument modelling and error propagation analysis, precision of 3 ppm.m.Hz-0.5 has been established (one sigma precision for atmospheric methane normalized over a 1 m path and 1 s measurement duration). The system was fully functional in the rain, sleet, and moderate fog. The physical model and system concept of CLaDS can be adapted to any greenhouse gas species. Currently we are developing an in-lab instrument that can measure carbon dioxide using a quantum cascade laser operating in the 4 μm range. In this case, the dynamic range benefit of CLaDS is used to provide high precision even when peak absorbance in the CO2 spectrum gets greater than 2. Development for this deployable CO2 measurement system is still at an early stage. So far laboratory gas cell experiments have demonstrated a 9.3 ppm.m.Hz-0.5 for CO2 monitoring. This corresponds to about 0.02% relative precision in measuring CO2 atmospheric background over a 100 m open-path in one second. 1 G. Wysocki and D. Weidmann, "Molecular dispersion spectroscopy for chemical sensing using chirped mid-infrared quantum cascade laser," Opt. Express 18(25), 26123-26140 (2010). 2 N.S. Daghestani, R. Brownsword, D. Weidmann, 'Analysis and demonstration of atmospheric methane monitoring by mid-infrared open-path chirped dispersion spectroscopy' Opt. Express 22(25), A1731-A1743 (2014).

Laser Resurfacing: Full Field and Fractional.

PubMed

Pozner, Jason N; DiBernardo, Barry E

2016-07-01

Laser resurfacing is a very popular procedure worldwide. Full field and fractional lasers are used in many aesthetic practices. There have been significant advances in laser resurfacing in the past few years, which make patient treatments more efficacious and with less downtime. Erbium and carbon dioxide and ablative, nonablative, and hybrid fractional lasers are all extremely effective and popular tools that have a place in plastic surgery and dermatology offices. Copyright © 2016 Elsevier Inc. All rights reserved.

Can transmyocardial CO2 laser channels supply nutritive blood flow into adjacent myocardium?

NASA Astrophysics Data System (ADS)

Kohmoto, Takushi; Fisher, Peter E.; DeRosa, Carolyn; Smith, Craig R.; Burkhoff, Daniel

1996-05-01

Clinical reports of transmyocardial laser revascularization (TMLR) suggest that this procedure is effective in relieving angina. However, experimental evidence of nutritive blood flow through the TMLR channels is not available. The purpose of this study was to test whether blood could flow through the TMLR channels created with the carbon-dioxide laser.

Cutaneous applications of lasers.

PubMed

Ries, W R; Speyer, M T

1996-12-01

The cutaneous application of lasers today includes more selective and less damaging devices. Carbon dioxide, neodymium:yttrium-aluminum-garnet, potassium titanyl phosphate, argon, and yellow lasers are most prevalent in treating cutaneous lesions. Specific techniques in skin resurfacing, keloid excision, rhinophyma, actinic cheilitis ablation, and excision of superficial cutaneous tumors are discussed. Proper management of cutaneous vascular lesions is also presented.

Terahertz Imaging of Subjects With Concealed Weapons

DTIC Science & Technology

2006-05-01

pulsed imaging", Advanced Characterization, Therapeutics, and Systems XIV, Proceedings of SPIE, Vol. 5318: 23-33 6. Anthony E. Siegman , Lasers , p667...imagery. Both methods made use of in-house transceivers, consisting of two ultra-stable far-infrared lasers , terahertz heterodyne detection systems...SYSTEM The 1.56THz transceiver system at STL uses two carbon dioxide lasers paired individually with two far-infrared lasers . All four units are

A 4 U Laser Heterodyne Radiometer for Methane (CH4) and Carbon Dioxide (CO2) Measurements from an Occultation-Viewing CubSat

NASA Technical Reports Server (NTRS)

Wilson, Emily L.; DiGregorio, A. J.; Riot, Vincent J.; Ammons, Mark S.; Bruner, WIlliam W.; Carter, Darrell; Mao, Jianping; Ramanathan, Anand; Strahan, Susan E.; Oman, Luke D.;

Dynamics and Fragmentation of Hydrogen Bonded and van der Waal Clusters upon 26.5 eV Soft X-ray Laser Ionization

NASA Astrophysics Data System (ADS)

Dong, Feng; Heinbuch, Scott; Bernstein, Elliot; Rocca, Jorge

2006-05-01

A desk-top soft x-ray laser is applied to the study of water, methanol, ammonia, sulfur dioxide, carbon dioxide, mixed sulfur dioxide-water, and mixed carbon dioxide-water clusters through single photon ionization time of flight mass spectroscopy. Almost all of the energy above the vertical ionization energy is removed by the ejected electron. Protonated water, methanol, and ammonia clusters dominate the mass spectra for the first three systems. The temperatures of the neutral water and methanol clusters can be estimated. In the case of pure SO2 and CO2, the mass spectra are dominated by (SO2)n^+ and (CO2)n^+ cluster series. When a high or low concentration of SO2/CO2 is mixed with water, we observe (SO2/CO2)nH2O^+ or SO2/CO2(H2O)nH^+ in the mass spectra, respectively. The unimolecular dissociation rate constants for reactions involving loss of one neutral molecule are calculated for the protonated water, methanol, and ammonia clusters as well as for SO2 and CO2 clusters. We find that the 26.5 eV soft x-ray laser is a nearly ideal tool for the study of hydrogen bonded and van der Waals cluster systems and we are currently exploring its usefulness for other more strongly bound systems.

Laser surface modification of decellularized extracellular cartilage matrix for cartilage tissue engineering.

PubMed

Goldberg-Bockhorn, Eva; Schwarz, Silke; Subedi, Rachana; Elsässer, Alexander; Riepl, Ricarda; Walther, Paul; Körber, Ludwig; Breiter, Roman; Stock, Karl; Rotter, Nicole

2018-02-01

The implantation of autologous cartilage as the gold standard operative procedure for the reconstruction of cartilage defects in the head and neck region unfortunately implicates a variety of negative effects at the donor site. Tissue-engineered cartilage appears to be a promising alternative. However, due to the complex requirements, the optimal material is yet to be determined. As demonstrated previously, decellularized porcine cartilage (DECM) might be a good option to engineer vital cartilage. As the dense structure of DECM limits cellular infiltration, we investigated surface modifications of the scaffolds by carbon dioxide (CO 2 ) and Er:YAG laser application to facilitate the migration of chondrocytes inside the scaffold. After laser treatment, the scaffolds were seeded with human nasal septal chondrocytes and analyzed with respect to cell migration and formation of new extracellular matrix proteins. Histology, immunohistochemistry, SEM, and TEM examination revealed an increase of the scaffolds' surface area with proliferation of cell numbers on the scaffolds for both laser types. The lack of cytotoxic effects was demonstrated by standard cytotoxicity testing. However, a thermal denaturation area seemed to hinder the migration of the chondrocytes inside the scaffolds, even more so after CO 2 laser treatment. Therefore, the Er:YAG laser seemed to be better suitable. Further modifications of the laser adjustments or the use of alternative laser systems might be advantageous for surface enlargement and to facilitate migration of chondrocytes into the scaffold in one step.

Room-temperature subnanosecond waveguide lasers in Nd:YVO4 Q-switched by phase-change VO2: A comparison with 2D materials

PubMed Central

Nie, Weijie; Li, Rang; Cheng, Chen; Chen, Yanxue; Lu, Qingming; Romero, Carolina; Vázquez de Aldana, Javier R.; Hao, Xiaotao; Chen, Feng

2017-01-01

We report on room-temperature subnanosecond waveguide laser operation at 1064 nm in a Nd:YVO4 crystal waveguide through Q-switching of phase-change nanomaterial vanadium dioxide (VO2). The unique feature of VO2 nanomaterial from the insulating to metallic phases offers low-saturation-intensity nonlinear absorptions of light for subnanosecond pulse generation. The low-loss waveguide is fabricated by using the femtosecond laser writing with depressed cladding geometry. Under optical pump at 808 nm, efficient pulsed laser has been achieved in the Nd:YVO4 waveguide, reaching minimum pulse duration of 690 ps and maximum output average power of 66.7 mW. To compare the Q-switched laser performances by VO2 saturable absorber with those based on two-dimensional materials, the 1064-nm laser pulses have been realized in the same waveguide platform with either graphene or transition metal dichalcogenide (in this work, WS2) coated mirror. The results on 2D material Q-switched waveguide lasers have shown that the shortest pulses are with 22-ns duration, whilst the maximum output average powers reach ~161.9 mW. This work shows the obvious difference on the lasing properties based on phase-change material and 2D materials, and suggests potential applications of VO2 as low-cost saturable absorber for subnanosecond laser generation. PMID:28383017

Efficiency of Carbon Dioxide Fractional Laser in Skin Resurfacing

PubMed Central

Petrov, Andrej

2016-01-01

AIM: The aim of the study was to confirm the efficiency and safety of the fractional CO2 laser in skin renewal and to check the possibility of having a synergistic effect in patients who besides carbon dioxide laser are treated with PRP (platelet-rich plasma) too. MATERIAL AND METHODS: The first group (Examined Group 1 or EG1) included 107 patients treated with fractional CO2 laser (Lutronic eCO2) as mono-therapy. The second group (Control Group or CG) covered 100 patients treated with neither laser nor plasma in the same period but subjected to local therapy with drugs or other physio-procedures under the existing protocols for treatment of certain diseases. The third group (Examined Group 2 or EG2) treated 25 patients with combined therapy of CO2 laser and PRP in the treatment of facial rejuvenation or treatment of acne scars. RESULTS: Patient’s satisfaction, in general, is significantly greater in both examined groups (EG1 and EG2) (p < 0.001). It was found the significant difference between control and examined group from the treatment in acne scar (Fisher exact two tailed p < 0.001). Patients satisfaction with the treatment effect in rejuvenation of the skin is significant (χ2 = 39.41; df = 4; p < 0.001). But, patients satisfaction from the treatment with HPV on the skin was significantly lower in examined group (treated with laser), p = 0.0002. CONCLUSION: Multifunctional fractional carbon dioxide laser used in treatment of patients with acne and pigmentation from acne, as well as in the treatment of scars from different backgrounds, is an effective and safe method that causes statistically significant better effect of the treatment, greater patients’ satisfaction, minimal side effects and statistically better response to the therapy, according to assessments by the patient and the therapist. PMID:27335599

Laser Corrective Surgery with Fractional Carbon Dioxide Laser Following Full-thickness Skin Grafts.

PubMed

Forbat, Emily; Ali, Faisal R; Mallipeddi, Raj; Al-Niaimi, Firas

2017-01-01

Full-thickness skin grafts (FTSGs) are frequently used to treat patients with burn injuries and to repair defects rendered by excisional (including Mohs) surgery. The evidence for corrective laser surgery after scar formation is well established. With regard to laser treatment of FTSG, the evidence is sparse. Laser treatment after FTSG is a novel concept, with minimal literature. We present a case series, one of the first to our knowledge, of the treatment of FTSG with fractional CO 2 laser in five patients after Mohs surgery.

Laser Spectroscopy Multi-Gas Monitor: Results of Technology Demonstration on ISS

NASA Technical Reports Server (NTRS)

Mudgett, Paul D.; Pilgrim, Jeffrey S.

2015-01-01

Tunable diode laser spectroscopy (TDLS) is an up and coming trace and major gas monitoring technology with unmatched selectivity, range and stability. The technology demonstration of the 4 gas Multi-Gas Monitor (MGM), reported at the 2014 ICES conference, operated continuously on the International Space Station (ISS) for nearly a year. The MGM is designed to measure oxygen, carbon dioxide, ammonia and water vapor in ambient cabin air in a low power, relatively compact device. While on board, the MGM experienced a number of challenges, unplanned and planned, including a test of the ammonia channel using a commercial medical ammonia inhalant. Data from the unit was downlinked once per week and compared with other analytical resources on board, notably the Major Constituent Analyzer (MCA), a magnetic sector mass spectrometer. MGM spent the majority of the time installed in the Nanoracks Frame 2 payload facility in front breathing mode (sampling the ambient environment of the Japanese Experiment Module), but was also used to analyze recirculated rack air. The capability of the MGM to be operated in portable mode (via internal rechargeable lithium ion polymer batteries or by plugging into any Express Rack 28VDC connector) was a part of the usability demonstration. Results to date show unprecedented stability and accuracy of the MGM vs. the MCA for oxygen and carbon dioxide. The ammonia challenge (approx. 75 ppm) was successful as well, showing very rapid response time in both directions. Work on an expansion of capability in a next generation MGM has just begun. Combustion products and hydrazine are being added to the measurable target analytes. An 8 to 10 gas monitor (aka Gas Tricorder 1.0) is envisioned for use on ISS, Orion and Exploration missions.

Results of a Long-Term Demonstration of an Optical Multi-Gas Monitor on ISS

NASA Technical Reports Server (NTRS)

Mudgett, Paul; Pilgrim, Jeffrey S.

2015-01-01

Previously at SAMAP we reported on the development of tunable diode laser spectroscopy (TDLS) based instruments for measuring small gas molecules in real time. TDLS technology has matured rapidly over the last 5 years as a result of advances in low power diode lasers as well as better detection schemes. In collaboration with two small businesses Vista Photonics, Inc. and Nanoracks LLC, NASA developed a 4 gas TDLS based monitor for an experimental demonstration of the technology on the International Space Station (ISS). Vista invented and constructed the core TDLS sensor. Nanoracks designed and built the enclosure, and certified the integrated monitor as a payload. The device, which measures oxygen, carbon dioxide, ammonia and water vapor, is called the Multi-Gas Monitor (MGM). MGM measures the 4 gases every few seconds and records a 30 second moving average of the concentrations. The relatively small unit draws only 2.5W. MGM was calibrated at NASA-Johnson Space Center in July 2013 and launched to ISS on a Soyuz vehicle in November 2013. Installation and activation of MGM occurred in February 2014, and the unit has been operating nearly continuously ever since in the Japanese Experiment Module. Data is downlinked from ISS about once per week. Oxygen and carbon dioxide data is compared with that from the central Major Constituents Analyzer. Water vapor data is compared with dew point measurements made by sensors in the Columbus module. The ammonia channel was tested by the crew using a commercial ammonia inhalant. MGM is remarkably stable to date. Results of 18 months of operation are presented and future applications including combustion product monitoring are discussed.

Direct thermal water splitting by concentrated solar radiation for hydrogen production. Phase O: Proof of concept experiment

NASA Technical Reports Server (NTRS)

Genequand, P.

1980-01-01

The direct production of hydrogen from water and solar energy concentrated into a high temperature aperture is described. A solar powered reactor able to dissociate water vapor and to separate the reaction product at high temperature was developed, and direct water splitting has been achieved in a laboratory reactor. Water vapor and radiative heating from a carbon dioxide laser are fed into the reactor, and water vapor enriched in hydrogen and water vapor enriched in oxygen are produced. The enriched water vapors are separated through a separation membrane, a small disc of zirconium dioxide heated to a range of 1800 k to 2800 k. To avoid water vapor condensation within the reactor, the total pressure within the reactor was limited to 0.15 torr. A few modifications would enable the reactor to be operated at an increased pressure of a few torrs. More substantial modifications would allow for a reaction pressure of 0.1 atmosphere.

Efficacy and safety of fractional carbon dioxide laser for treatment of unwanted facial freckles in phototypes II-IV: a pilot study.

PubMed

El Zawahry, Bakr; Zaki, Naglaa; Hafez, Vanessa; Abdel Hay, Rania; Hay, Rania Abdel; Fahim, Aya

2014-11-01

Facial freckles are a cosmetic concern to Egyptians, particularly young females. Several therapeutic lines exist with variable response rates and limitations. Fractional carbon dioxide (FCO2) laser provides minimal ablation and therefore less down time and less side effects. The efficacy and safety of this laser technology have still not been studied in freckles. The aim of this study is to assess the efficacy and safety of FCO2 laser in the treatment of unwanted facial freckles in Egyptians. Twenty patients undergone a single session of FCO2 laser and then were followed up clinically a month later. Photographs were taken before treatment and at follow-up visit and were assessed by three blinded investigators. Percent of global improvement was measured on a 4-point grading scale. Patient's satisfaction and adverse events were recorded. Two patients (10 %) showed grade 1 improvement, while eight patients (40 %) showed grade 2 improvement. Nine patients (45 %) showed grade 3 improvement, and only one patient (5 %) showed grade 4 improvement. FCO2 laser resurfacing is effective and safe in treatment of facial freckles in skin phototypes II-IV. It can offer a more practical alternative to topical treatments, and a cheaper alternative to Q-switched lasers.

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

Dental hard tissue characterization using laser-based ultrasonics

NASA Astrophysics Data System (ADS)

Blodgett, David W.; Massey, Ward L.

2003-07-01

Dental health care and research workers require a means of imaging the structures within teeth in vivo. One critical need is the detection of tooth decay in its early stages. If decay can be detected early enough, the process can be monitored and interventional procedures, such as fluoride washes and controlled diet, can be initiated to help re-mineralize the tooth. Currently employed x-ray imaging is limited in its ability to visualize interfaces and incapable of detecting decay at a stage early enough to avoid invasive cavity preparation followed by a restoration. To this end, non-destructive and non-contact in vitro measurements on extracted human molars using laser-based ultrasonics are presented. Broadband ultrasonic waves are excited in the extracted sections by using a pulsed carbon-dioxide (CO2) laser operating in a region of high optical absorption in the dental hard tissues. Optical interferometric detection of the ultrasonic wave surface displacements in accomplished with a path-stabilized Michelson-type interferometer. Results for bulk and surface in-vitro characterization of caries are presented on extracted molars with pre-existing caries.

Nanoparticle Thin Films for Gas Sensors Prepared by Matrix Assisted Pulsed Laser Evaporation

PubMed Central

Caricato, Anna Paola; Luches, Armando; Rella, Roberto

2009-01-01

The matrix assisted pulsed laser evaporation (MAPLE) technique has been used for the deposition of metal dioxide (TiO2, SnO2) nanoparticle thin films for gas sensor applications. For this purpose, colloidal metal dioxide nanoparticles were diluted in volatile solvents, the solution was frozen at the liquid nitrogen temperature and irradiated with a pulsed excimer laser. The dioxide nanoparticles were deposited on Si and Al2O3 substrates. A rather uniform distribution of TiO2 nanoparticles with an average size of about 10 nm and of SnO2 nanoparticles with an average size of about 3 nm was obtained, as demonstrated by high resolution scanning electron microscopy (SEM-FEG) inspections. Gas-sensing devices based on the resistive transduction mechanism were fabricated by depositing the nanoparticle thin films onto suitable rough alumina substrates equipped with interdigitated electrical contacts and heating elements. Electrical characterization measurements were carried out in controlled environment. The results of the gas-sensing tests towards low concentrations of ethanol and acetone vapors are reported. Typical gas sensor parameters (gas responses, response/recovery time, sensitivity, and low detection limit) towards ethanol and acetone are presented. PMID:22574039

Nanoparticle thin films for gas sensors prepared by matrix assisted pulsed laser evaporation.

PubMed

Caricato, Anna Paola; Luches, Armando; Rella, Roberto

2009-01-01

The matrix assisted pulsed laser evaporation (MAPLE) technique has been used for the deposition of metal dioxide (TiO(2), SnO(2)) nanoparticle thin films for gas sensor applications. For this purpose, colloidal metal dioxide nanoparticles were diluted in volatile solvents, the solution was frozen at the liquid nitrogen temperature and irradiated with a pulsed excimer laser. The dioxide nanoparticles were deposited on Si and Al(2)O(3) substrates. A rather uniform distribution of TiO(2) nanoparticles with an average size of about 10 nm and of SnO(2) nanoparticles with an average size of about 3 nm was obtained, as demonstrated by high resolution scanning electron microscopy (SEM-FEG) inspections. Gas-sensing devices based on the resistive transduction mechanism were fabricated by depositing the nanoparticle thin films onto suitable rough alumina substrates equipped with interdigitated electrical contacts and heating elements. Electrical characterization measurements were carried out in controlled environment. The results of the gas-sensing tests towards low concentrations of ethanol and acetone vapors are reported. Typical gas sensor parameters (gas responses, response/recovery time, sensitivity, and low detection limit) towards ethanol and acetone are presented.

40 CFR 62.15175 - What continuous emission monitoring systems must I install for gaseous pollutants?

Code of Federal Regulations, 2010 CFR

2010-07-01

..., maintain, and operate continuous emission monitoring systems for oxygen (or carbon dioxide), sulfur dioxide, and carbon monoxide. If you operate a Class I municipal waste combustion unit, also install, calibrate... emission monitoring system for sulfur dioxide, nitrogen oxides, and oxygen (or carbon dioxide) at the...

40 CFR 60.1720 - What continuous emission monitoring systems must I install for gaseous pollutants?

Code of Federal Regulations, 2011 CFR

2011-07-01

..., maintain, and operate continuous emission monitoring systems for oxygen (or carbon dioxide), sulfur dioxide, and carbon monoxide. If you operate a Class I municipal waste combustion unit, also install, calibrate... emission monitoring systems for sulfur dioxide, nitrogen oxides, and oxygen (or carbon dioxide) at the...

40 CFR 60.1720 - What continuous emission monitoring systems must I install for gaseous pollutants?

Code of Federal Regulations, 2010 CFR

2010-07-01

..., maintain, and operate continuous emission monitoring systems for oxygen (or carbon dioxide), sulfur dioxide, and carbon monoxide. If you operate a Class I municipal waste combustion unit, also install, calibrate... emission monitoring systems for sulfur dioxide, nitrogen oxides, and oxygen (or carbon dioxide) at the...

40 CFR 62.15175 - What continuous emission monitoring systems must I install for gaseous pollutants?

Code of Federal Regulations, 2011 CFR

2011-07-01

..., maintain, and operate continuous emission monitoring systems for oxygen (or carbon dioxide), sulfur dioxide, and carbon monoxide. If you operate a Class I municipal waste combustion unit, also install, calibrate... emission monitoring system for sulfur dioxide, nitrogen oxides, and oxygen (or carbon dioxide) at the...

High-sensitivity remote detection of atmospheric pollutants and greenhouse gases at low ppm levels using near-infrared tunable diode lasers

NASA Astrophysics Data System (ADS)

Roy, Anirban; Upadhyay, Abhishek; Chakraborty, Arup Lal

2016-05-01

The concentration of atmospheric pollutants and greenhouse gases needs to be precisely monitored for sustainable industrial development and to predict the climate shifts caused by global warming. Such measurements are made on a continuous basis in ecologically sensitive and urban areas in the advanced countries. Tunable diode laser spectroscopy (TDLS) is the most versatile non-destructive technology currently available for remote measurements of multiple gases with very high selectivity (low cross-sensitivity), very high sensitivity (on the order of ppm and ppb) and under hazardous conditions. We demonstrate absolute measurements of acetylene, methane and carbon dioxide using a fielddeployable fully automated TDLS system that uses calibration-free 2f wavelength modulation spectroscopy (2f WMS) techniques with sensitivities of low ppm levels. A 40 mW, 1531.52 nm distributed feedback (DFB) diode laser, a 10 mW, 1650 nm DFB laser and a 1 mW, 2004 nm vertical cavity surface emitting laser (VCSEL) are used in the experiments to probe the P9 transition of acetylene, R4 transition of methane and R16 transition of carbon dioxide respectively. Data acquisition and on-board analysis comprises a Raspberry Pi-based embedded system that is controllable over a wireless connection. Gas concentration and pressure are simultaneously extracted by fitting the experimental signals to 2f WMS signals simulated using spectroscopic parameters obtained from the HITRAN database. The lowest detected concentration is 11 ppm for acetylene, 275 ppm for methane and 285 ppm for carbon dioxide using a 28 cm long single-pass gas cell.

"Application of Tunable Diode Laser Spectrometry to Isotopic Studies for Exobiology"

NASA Technical Reports Server (NTRS)

Sauke, Todd B.

1999-01-01

Computer-controlled electrically-activated valves for rapid gas-handling have been incorporated into the Stable Isotope Laser Spectrometer (SILS) which now permits rapid filling and evacuating of the sample and reference gas cells, Experimental protocols have been developed to take advantage of the fast gas handling capabilities of the instrument and to achieve increased accuracy which results from reduced instrumental drift during rapid isotopic ratio measurements. Using these protocols' accuracies of 0.5 del (0.05%) have been achieved in measurements of 13C/12C in carbon dioxide. Using the small stable isotope laser spectrometer developed in a related PIDDP project of the Co-I, protocols for acquisition of rapid sequential calibration spectra were developed which resulted in 0.5 del accuracy also being achieved in this less complex instrument. An initial version of software for automatic characterization of tunable diode lasers has been developed and diodes have been characterized in order to establish their spectral output properties. A new state-of-the-art high operating temperature (200 K) mid infrared diode laser was purchased (through NASA procurement) and characterized. A thermo-electrically cooled mid infrared tunable diode laser system for use with high temperature operation lasers was developed. In addition to isotopic ratio measurements of carbon and oxygen, measurements of a third biologically important element (15N/14N in N2O gas) have been achieved to a preliminary accuracy of about 0.2%. Transfer of the basic SILS technology to the commercial sector is proceeding under an unfunded Space Act Agreement between NASA and SpiraMed, a medical diagnostic instrument company. Two patents have been issued. Foreign patents based on these two US patents have been applied for and are expected to be issued. A preliminary design was developed for a thermo-electrically cooled SILS instruments for application to planetary space flight exploration missions.

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.

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.

Designing Catalytic Monoliths For Closed-Cycle CO2 Lasers

NASA Technical Reports Server (NTRS)

Guinn, Keith; Herz, Richard K.; Goldblum, Seth; Noskowski, ED

1992-01-01

LASCAT (Design of Catalytic Monoliths for Closed-Cycle Carbon Dioxide Lasers) computer program aids in design of catalyst in monolith by simulating effects of design decisions on performance of laser. Provides opportunity for designer to explore tradeoffs among activity and dimensions of catalyst, dimensions of monolith, pressure drop caused by flow of gas through monolith, conversion of oxygen, and other variables. Written in FORTRAN 77.

Heat pump processes induced by laser radiation

NASA Technical Reports Server (NTRS)

Garbuny, M.; Henningsen, T.

1980-01-01

A carbon dioxide laser system was constructed for the demonstration of heat pump processes induced by laser radiation. The system consisted of a frequency doubling stage, a gas reaction cell with its vacuum and high purity gas supply system, and provisions to measure the temperature changes by pressure, or alternatively, by density changes. The theoretical considerations for the choice of designs and components are dicussed.

High Power and Frequency-Agile Optical Parametric Oscillators for Airborne DIAL Measurements of CH4 and H2O

NASA Astrophysics Data System (ADS)

Nehrir, A. R.; Shuman, T.; Chuang, T.; Hair, J. W.; Refaat, T. F.; Ismail, S.; Kooi, S. A.; Notari, A.

2014-12-01

Atmospheric methane (CH4) has the second largest radiative forcing of the long-lived greenhouse gasses (GHG) after carbon dioxide. However, methane's much shorter atmospheric lifetime and much stronger warming potential make its radiative forcing equivalent to that for CO2 over a 20-year time horizon which makes CH4 a particularly attractive target for mitigation strategies. Similar to CH4, water vapor (H2O) is the most dominant of the short-lived GHG in the atmosphere and plays a key role in many atmospheric processes. Atmospheric H2O concentrations span over four orders of magnitude from the planetary boundary layer where high impact weather initiates to lower levels in the upper troposphere and lower stratosphere (UTLS) where water vapor has significant and long term impacts on the Earth's radiation budget. NASA Langley has fostered the technology development with Fibertek, Inc. to develop frequency agile and high power (> 3 W) pulsed lasers using similar architectures in the 1645 nm and 935 nm spectral bands for DIAL measurements of CH4 and H2O, respectively. Both systems utilize high power 1 kHz pulse repetition frequency Nd:YAG lasers to generate high power laser emission at the desired wavelength via optical parametric oscillators (OPO). The CH4 OPO, currently in its final build stage in a SBIR Phase II program has demonstrated >2 W average power with injection seeding from a distributed feedback (DFB) laser during risk reduction experiments. The H2O OPO has demonstrated high power operation (>2 W) during the SBIR Phase I program while being injection seeded with a DFB laser, and is currently funded via an SBIR Phase II to build a robust system for future integration into an airborne water vapor DIAL system capable of profiling from the boundary layer up to the UTLS. Both systems have demonstrated operation with active OPO wavelength control to allow for optimization of the DIAL measurements for operation at different altitudes and geographic regions. An update on the progress of the CH4 and H2O laser development will be presented which will focus on key laser characteristics such as pulse energy, frequency agility and spectral purity. DIAL simulations will also be presented based on the expected and measured laser characteristics and system parameters in anticipation of future system(s) development.

Laser machining wood composites

Treesearch

Vladimir Barnekov; Henry A. Huber; Charles W. McMillin

1989-01-01

This practical, nonstatistical experiment using commercial equipment demonstrated that nominal 3/4-inch compositep anelsf or furniture consisting of a particleboard core,h igh density melamine crossbands, and walnut veneer face plies can be cut with a carbon dioxide/airjet-assisted laser to produce surfaces with minimal nonparallelism and char compared to previous...

Management of a Recurrent Pyogenic Granuloma of the Hard Palate with Diode Laser: A Case Report.

PubMed

Hasanoglu Erbasar, Güzin Neda; Senguven, Burcu; Gultekin, Sibel Elif; Cetiner, Sedat

2016-01-01

Pyogenic granuloma (PG) is a prevalent inflammatory hyperplasia of skin and oral mucosa which is often caused by constant low-grade local irritation, traumatic injury or hormonal factors. In many cases, gingival irritation and inflammation due to poor oral hygiene are precipitating factors. Oral PG occurs predominantly on the gingiva, but it is also encountered on the lips, tongue, buccal mucosa and rarely on the hard palate. Although surgical excision is the first choice of treatment, many other treatment modalities could be counted such as cryosurgery, sodium tetradecyl sulfate sclerotherapy, intralesional steroids, flash lamp pulsed dye laser, neodymium-doped yttrium aluminium garnet (Nd:YAG) laser, carbon dioxide (CO2) laser, erbium-doped yttrium aluminum garnet (Er:YAG) lasers and diode laser have been suggested. After surgical excision recurrence occurs up to 16% of these lesions. It is believed that recurrence ensues as a result of incomplete excision, failure to eliminate etiologic factors or repeated trauma. A 50-year-old female was referred to the Department of Oral Surgery, Gazi University, School of Dentistry, complaining of a swelling and growth on the right side of the hard palate for four months. Patient reported a similar growth in the same area about two years earlier, which had turned out to be a PG by histopathology. The treatment plan included surgical excision of the lesion using diode laser. The patient reported no pain after the surgery. She was discharged with a prescription of chlorhexidine mouthwash and necessary post-operative instructions. At 7 days follow up visit, immediate recurrence of the lesion was observed, and it was excised by diode laser with 2 mm margins at its clinical periphery, to a depth up to the periosteum, by the same operator. No recurrence or scarring was observed in 14 months follow-up. Although diode laser is a secure and efficient technique for the treatment of intraoral PG, in order to minimize its recurrence, the lesion should be excised with a wider margin down to the periosteum or to the causing agent. Also due to its high recurrence rate, long-term follow-up is recommended.

Novel diode laser-based sensors for gas sensing applications

NASA Technical Reports Server (NTRS)

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

2000-01-01

The development of compact spectroscopic gas sensors and their applications to environmental sensing will be described. These sensors employ mid-infrared difference-frequency generation (DFG) in periodically poled lithium niobate (PPLN) crystals pumped by two single-frequency solid state lasers such as diode lasers, diode-pumped solid state, and fiber lasers. Ultrasensitive, highly selective, and real-time measurements of several important atmospheric trace gases, including carbon monoxide, nitrous oxide, carbon dioxide, formaldehyde [correction of formaldehye], and methane, have been demonstrated.

Manufacturing Methods and Technology (MM&T) Program. 10.6 Micrometer Carbon Dioxide TEA (Transverely Excited Atmospheric) Lasers

DTIC Science & Technology

1983-06-01

TBE LV I R , VA 22060 DISTRIBUTION STATEMENT s Approved for public release, distribution unlimited. Prepared by DR. CLARENCE F. LUCK RAYTHEON COMPANY0...Polaroid photographic records of interferograms of test optical elements. xvii/xviii . i .’’ . r *’. ~ ~ s . -’- * INTRODUCTION/SUMMARY In April 1981...SEPTUM Q LASER-SIDE VALVE PINCH-OFF TUBES O oo LASER EOA-3224 Figure 7. Laser Plumbing 16 I .4. . I 4",’ : ."," , r

A 4 U laser heterodyne radiometer for methane (CH4) and carbon dioxide (CO2) measurements from an occultation-viewing CubeSat

NASA Astrophysics Data System (ADS)

Wilson, Emily L.; DiGregorio, A. J.; Riot, Vincent J.; Ammons, Mark S.; Bruner, William W.; Carter, Darrell; Mao, Jianping; Ramanathan, Anand; Strahan, Susan E.; Oman, Luke D.; Hoffman, Christine; Garner, Richard M.

2017-03-01

We present a design for a 4 U (20 cm  ×  20 cm  ×  10 cm) occultation-viewing laser heterodyne radiometer (LHR) that measures methane (CH4), carbon dioxide (CO2) and water vapor (H2O) in the limb that is designed for deployment on a 6 U CubeSat. The LHR design collects sunlight that has undergone absorption by the trace gas and mixes it with a distributive feedback (DFB) laser centered at 1640 nm that scans across CO2, CH4, and H2O absorption features. Upper troposphere/lower stratosphere measurements of these gases provide key inputs to stratospheric circulation models: measuring stratospheric circulation and its variability is essential for projecting how climate change will affect stratospheric ozone.

Development of an Airborne Triple-Pulse 2-Micron Integrated Path Differential Absorption Lidar (IPDA) for Simultaneous Airborne Column Measurements of Carbon Dioxide and Water Vapor in the Atmosphere

NASA Technical Reports Server (NTRS)

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

2016-01-01

This presentation will provide status and details of an airborne 2-micron triple-pulse integrated path differential absorption (IPDA) lidar being developed at NASA Langley Research Center with support from NASA ESTO Instrument Incubator Program. The development of this active optical remote sensing IPDA instrument is targeted for measuring both atmospheric carbon dioxide and water vapor in the atmosphere from an airborne platform. This presentation will focus on the advancement of the 2-micron triple-pulse IPDA lidar development. Updates on the state-of-the-art triple-pulse laser transmitter will be presented including the status of seed laser locking, wavelength control, receiver and detector upgrades, laser packaging and lidar integration. Future plan for IPDA lidar system for ground integration, testing and flight validation will also be presented.

A strategic decision-making model considering the social costs of carbon dioxide emissions for sustainable supply chain management.

PubMed

Tseng, Shih-Chang; Hung, Shiu-Wan

2014-01-15

Incorporating sustainability into supply chain management has become a critical issue driven by pressures from governments, customers, and various stakeholder groups over the past decade. This study proposes a strategic decision-making model considering both the operational costs and social costs caused by the carbon dioxide emissions from operating such a supply chain network for sustainable supply chain management. This model was used to evaluate carbon dioxide emissions and operational costs under different scenarios in an apparel manufacturing supply chain network. The results showed that the higher the social cost rate of carbon dioxide emissions, the lower the amount of the emission of carbon dioxide. The results also suggested that a legislation that forces the enterprises to bear the social costs of carbon dioxide emissions resulting from their economic activities is an effective approach to reducing carbon dioxide emissions. Copyright © 2013 Elsevier Ltd. All rights reserved.

United States Air Force Summer Faculty Research Program: Program Management Report

DTIC Science & Technology

1988-12-01

Laboratory 64 Realization of Sublayer Relative Dr. Lane Clark Shielding Order in Electromagnetic Topology 65 Diode Laser Probe of Vibrational Dr. David...given. In addition, all possible sublayer topologies with relative shielding order at most 5 are explicitly given. S863 Diode Laser Probe of...dioxide at 193 nm to prepare the SO radicals. High resolution diode laser absorption spectrometry will be used to obtain time-dependent concentrations

Histopathology of laser skin resurfacing

NASA Astrophysics Data System (ADS)

Thomsen, Sharon L.; Baldwin, Bonnie; Chi, Eric; Ellard, Jeff; Schwartz, Jon A.

1997-05-01

Pulsed carbon-dioxide laser skin resurfacing is a purportedly 'non-thermal' procedure enjoying wide application as a cosmetic treatment for skin wrinkles. Treatment success has been based on clinical assessments of skin smoothness. Skin lesions (1 cm2) created by one, two or three superimposed carbon-dioxide laser passes were placed on the backs of 28 'fuzzy' Harlan Sprague Dawley rats. The variable laser irradiation parameters included measured energies ranging from 112 to 387/pulse with pulse widths of 65 and 125 microseconds and a repetition rate of 8 Hz. The square, flat laser beam measured 3 mm2 at the focal point. The lesions were collected from 0 to 10 days after treatment for qualitative and quantitative histopathology. Thermal damage and treatment effect tended to increase in severity and, to a lesser extent, depth with increased delivery parameters. In acute lesions, the vacuolated and fragmented, desiccated and thermally coagulated epidermis was partially removed exposing the underlying thermally coagulated dermal collagen and cells. Epidermal and dermal necrosis and slough occurred between 24 to 72 hours after treatment. Epithelial regeneration originated from the adnexa and the lesion edges. Dermal fibrous scar formation began at 5 days below the regenerated epidermis and became more prominent at 7 and 10 days.

Fractional ablative carbon dioxide laser followed by topical sodium stibogluconate application: A treatment option for pediatric cutaneous leishmaniasis.

PubMed

Hilerowicz, Yuval; Koren, Amir; Mashiah, Jacob; Katz, Oren; Sprecher, Eli; Artzi, Ofir

2018-05-01

Leishmaniasis is a protozoan zoonotic parasitic infection with cutaneous, mucocutaneous, and visceral manifestations. Israel is endemic for cutaneous leishmaniasis, which is a self-limited disease but is associated with scarring, which is often a source of psychological and social burden for patients. Scars can be especially devastating for children and teenagers. A wide range of physical and medical approaches is used to treat cutaneous leishmaniasis, among which intralesional injections of sodium stibogluconate rank among the most frequently used. Unfortunately, despite being effective, this therapeutic modality can be very painful. Fractional ablative laser creates a controlled mesh-like pattern of tissue ablation in the skin that promotes dermal remodeling and collagen production while at the same time facilitating enhanced delivery of topically applied medications. Patients were treated with fractional ablative carbon dioxide laser followed by immediate topical application of sodium stibogluconate. All children were diagnosed with cutaneous leishmaniasis prior to treatment initiation.. Ten children were treated. One leishmania tropica-positive girl failed to respond. The other nine patients achieved clinical cure and demonstrated good to excellent final cosmesis. Self-rated patient satisfaction and tolerance were high No adverse effects were observed or reported during treatment. Fractional ablative carbon dioxide laser followed by topical sodium stibogluconate application appears to be a safe and promising treatment for cutaneous leishmaniasis infection in children. Future controlled studies are required to validate these findings and compare this technique with traditional approaches. © 2018 Wiley Periodicals, Inc.

Column carbon dioxide and water vapor measurements by an airborne triple-pulse integrated path differential absorption lidar: novel lidar technologies and techniques with path to space

NASA Astrophysics Data System (ADS)

Singh, U. N.; Petros, M.; Refaat, T. F.; Yu, J.; Ismail, S.

2017-09-01

The 2-micron wavelength region is suitable for atmospheric carbon dioxide (CO2) measurements due to the existence of distinct absorption features for the gas at this wavelength region [1]. For more than 20 years, researchers at NASA Langley Research Center (LaRC) have developed several high-energy and high repetition rate 2-micron pulsed lasers [2]. Currently, LaRC team is engaged in designing, developing and demonstrating a triple-pulsed 2-micron direct detection Integrated Path Differential Absorption (IPDA) lidar to measure the weighted-average column dry-air mixing ratios of carbon dioxide (XCO2) and water vapor (XH2O) from an airborne platform [1, 3-5]. This novel technique allows measurement of the two most dominant greenhouse gases, simultaneously and independently, using a single instrument. This paper will provide status and details of the development of this airborne 2-micron triple-pulse IPDA lidar. The presented work will focus on the advancement of critical IPDA lidar components. Updates on the state-of-the-art triple-pulse laser transmitter will be presented including the status of seed laser locking, wavelength control, receiver and detector upgrades, laser packaging and lidar integration. Future plans for IPDA lidar ground integration, testing and flight validation will also be discussed. This work enables new Earth observation measurements, while reducing risk, cost, size, volume, mass and development time of required instruments.

Optical Design And Analysis Of Carbon Dioxide Laser Fusion Systems Using Interferometry And Fast Fourier Transform Techniques

NASA Astrophysics Data System (ADS)

Viswanathan, V. K.

1980-11-01

The optical design and analysis of the LASL carbon dioxide laser fusion systems required the use of techniques that are quite different from the currently used method in conventional optical design problems. The necessity for this is explored and the method that has been successfully used at Los Alamos to understand these systems is discussed with examples. This method involves characterization of the various optical components in their mounts by a Zernike polynomial set and using fast Fourier transform techniques to propagate the beam, taking diffraction and other nonlinear effects that occur in these types of systems into account. The various programs used for analysis are briefly discussed.

Imprinting on empty hard gelatin capsule shells containing titanium dioxide by application of the UV laser printing technique.

PubMed

Hosokawa, Akihiro; Kato, Yoshiteru; Terada, Katsuhide

2014-08-01

The purpose of this study was to examine the application of ultraviolet (UV) laser irradiation to printing hard gelatin capsule shells containing titanium dioxide (TiO2) and to clarify how the color strength of the printing by the laser could be controlled by the power of the irradiated laser. Hard gelatin capsule shells containing 3.5% TiO2 were used in this study. The capsules were irradiated with pulsed UV laser at a wavelength of 355 nm. The color strength of the printed capsule was determined by a spectrophotometer as total color difference (dE). The capsules could be printed gray by the UV laser. The formation of many black particles which were agglomerates of oxygen-defected TiO2 was associated with the printing. In the relationship between laser peak power of a pulse and dE, there were two inflection points. The lower point was the minimal laser peak power to form the black particles and was constant regardless of the dosage forms, for example film-coated tablets, soft gelatin capsules and hard gelatin capsules. The upper point was the minimal laser peak power to form micro-bubbles in the shells and was variable with the formulation. From the lower point to the upper point, the capsules were printed gray and the dE of the printing increased linearly with the laser peak power. Hard gelatin capsule shells containing TiO2 could be printed gray using the UV laser printing technique. The color strength of the printing could be controlled by regulating the laser energy between the two inflection points.

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..

Room temperature ferromagnetism in liquid-phase pulsed laser ablation synthesized nanoparticles of nonmagnetic oxides

NASA Astrophysics Data System (ADS)

Singh, S. C.; Kotnala, R. K.; Gopal, R.

2015-08-01

Intrinsic Room Temperature Ferromagnetism (RTF) has been observed in undoped/uncapped zinc oxide and titanium dioxide spherical nanoparticles (NPs) obtained by a purely green approach of liquid phase pulsed laser ablation of corresponding metal targets in pure water. Saturation magnetization values observed for zinc oxide (average size, 9 ± 1.2 nm) and titanium dioxide (average size, 4.4 ± 0.3 nm) NPs are 62.37 and 42.17 memu/g, respectively, which are several orders of magnitude larger than those of previous reports. In contrast to the previous works, no postprocessing treatments or surface modification is required to induce ferromagnetism in the case of present communication. The most important result, related to the field of intrinsic ferromagnetism in nonmagnetic materials, is the observation of size dependent ferromagnetism. Degree of ferromagnetism in titanium dioxide increases with the increase in particle size, while it is reverse for zinc oxide. Surface and volume defects play significant roles for the origin of RTF in zinc oxide and titanium dioxide NPs, respectively. Single ionized oxygen and neutral zinc vacancies in zinc oxide and oxygen and neutral/ionized titanium vacancies in titanium dioxide are considered as predominant defect centres responsible for observed ferromagnetism. It is expected that origin of ferromagnetism is a consequence of exchange interactions between localized electron spin moments resulting from point defects.

Room temperature ferromagnetism in liquid-phase pulsed laser ablation synthesized nanoparticles of nonmagnetic oxides

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

Singh, S. C., E-mail: subhash.laserlab@gmail.com; Gopal, R.; Kotnala, R. K.

2015-08-14

Intrinsic Room Temperature Ferromagnetism (RTF) has been observed in undoped/uncapped zinc oxide and titanium dioxide spherical nanoparticles (NPs) obtained by a purely green approach of liquid phase pulsed laser ablation of corresponding metal targets in pure water. Saturation magnetization values observed for zinc oxide (average size, 9 ± 1.2 nm) and titanium dioxide (average size, 4.4 ± 0.3 nm) NPs are 62.37 and 42.17 memu/g, respectively, which are several orders of magnitude larger than those of previous reports. In contrast to the previous works, no postprocessing treatments or surface modification is required to induce ferromagnetism in the case of present communication. The most important result, relatedmore » to the field of intrinsic ferromagnetism in nonmagnetic materials, is the observation of size dependent ferromagnetism. Degree of ferromagnetism in titanium dioxide increases with the increase in particle size, while it is reverse for zinc oxide. Surface and volume defects play significant roles for the origin of RTF in zinc oxide and titanium dioxide NPs, respectively. Single ionized oxygen and neutral zinc vacancies in zinc oxide and oxygen and neutral/ionized titanium vacancies in titanium dioxide are considered as predominant defect centres responsible for observed ferromagnetism. It is expected that origin of ferromagnetism is a consequence of exchange interactions between localized electron spin moments resulting from point defects.« less

Airborne laser systems for atmospheric sounding in the near infrared

NASA Astrophysics Data System (ADS)

Sabatini, Roberto; Richardson, Mark A.; Jia, Huamin; Zammit-Mangion, David

2012-06-01

This paper presents new techniques for atmospheric sounding using Near Infrared (NIR) laser sources, direct detection electro-optics and passive infrared imaging systems. These techniques allow a direct determination of atmospheric extinction and, through the adoption of suitable inversion algorithms, the indirect measurement of some important natural and man-made atmospheric constituents, including Carbon Dioxide (CO2). The proposed techniques are suitable for remote sensing missions performed by using aircraft, satellites, Unmanned Aerial Vehicles (UAV), parachute/gliding vehicles, Roving Surface Vehicles (RSV), or Permanent Surface Installations (PSI). The various techniques proposed offer relative advantages in different scenarios. All are based on measurements of the laser energy/power incident on target surfaces of known geometric and reflective characteristics, by means of infrared detectors and/or infrared cameras calibrated for radiance. Experimental results are presented relative to ground and flight trials performed with laser systems operating in the near infrared (NIR) at λ = 1064 nm and λ = 1550 nm. This includes ground tests performed with 10 Hz and 20 KHz PRF NIR laser systems in a variety of atmospheric conditions, and flight trials performed with a 10 Hz airborne NIR laser system installed on a TORNADO aircraft, flying up to altitudes of 22,000 ft above ground level. Future activities are planned to validate the atmospheric retrieval algorithms developed for CO2 column density measurements, with emphasis on aircraft related emissions at airports and other high air-traffic density environments.

Optical damage observed in the LHMEL II output coupler

NASA Astrophysics Data System (ADS)

Eric, John J.; Bagford, John O.; Devlin, Christie L. H.; Hull, Robert J.; Seibert, Daniel B.

2008-01-01

During the annual NIST calibration testing done at the LHMEL facility in FY06 on its high energy Carbon-Dioxide lasers, the LHMEL II device suffered severe damage to the internal surface of its ZnSe output coupler optics. The damage occurred during a high power, short duration run and it was believed to have been the result of a significant amount of surface contaminants interacting with the LHMEL cavity beam. Initial theories as to the source of the contamination led to the inspection of the vacuum grease that seals the piping that supplies the source gases to the laser cavity. Other contamination sources were considered, and analysis was conducted in an effort to identify the material found at the damage sites on the optic, but the tests were mainly inconclusive. Some procedure changes were initiated to identify possible contamination before high energy laser operation in an attempt to mitigate and possibly prevent the continued occurrence of damage to the output coupler window. This paper is to illustrate the type and extent of the damage encountered, highlight some of the theories as to the contamination source, and serve as a notice as to the severity and consequences of damage that is possible even due to small amounts of foreign material in a high energy laser environment.

Effect of Novel Quercetin Titanium Dioxide-Decorated Multi-Walled Carbon Nanotubes Nanocomposite on Bacillus subtilis Biofilm Development

PubMed Central

Raie, Diana S.; Mhatre, Eisha; El-Desouki, Doaa S.; Labena, Ahmed; El-Ghannam, Gamal; Farahat, Laila A.; Youssef, Tareq; Fritzsche, Wolfgang; Kovács, Ákos T.

2018-01-01

The present work was targeted to design a surface against cell seeding and adhering of bacteria, Bacillus subtilis. A multi-walled carbon nanotube/titanium dioxide nano-power was produced via simple mixing of carbon nanotube and titanium dioxide nanoparticles during the sol-gel process followed by heat treatment. Successfully, quercetin was immobilized on the nanocomposite via physical adsorption to form a quercetin/multi-walled carbon nanotube/titanium dioxide nanocomposite. The adhesion of bacteria on the coated-slides was verified after 24 h using confocal laser-scanning microscopy. Results indicated that the quercetin/multi-walled carbon nanotube/titanium dioxide nanocomposite had more negativity and higher recovery by glass surfaces than its counterpart. Moreover, coating surfaces with the quercetin-modified nanocomposite lowered both hydrophilicity and surface-attached bacteria compared to surfaces coated with the multi-walled carbon nanotubes/titanium dioxide nanocomposite. PMID:29346268

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.

Urologic laser types and instrumentation.

PubMed

Natalin, Ricardo A; Phillips, Courtney K; Clayman, Ralph V; Landman, Jaime

2008-11-01

Though the primary role of lasers in urology has always been in the treatment of urolithiasis, there are several other indications for their use. There are many different types of lasers currently available, each with unique properties conducive to treating certain disorders. As such, it is critical that today's urologist understands each laser's characteristics in order to optimize patient selection and treatment. The lasers which are primarily used in urologic applications include the carbon dioxide (CO2) laser; the Neodymium:Yttrium-Aluminum-Garnet (Nd:YAG); the Potassium Titanyl Phosphate (KTP) laser and the Holmium:YAG (Ho:YAG) laser. This review focuses on the unique characteristics of each of these lasers as well as the instrumentation needed utilize and deploy these tools in the urinary tract.

Study on elucidation of bactericidal effects induced by laser beam irradiation Measurement of dynamic stress on laser irradiated surface

NASA Astrophysics Data System (ADS)

Furumoto, Tatsuaki; Kasai, Atsushi; Tachiya, Hiroshi; Hosokawa, Akira; Ueda, Takashi

2010-09-01

In dental treatment, many types of laser beams have been used for various surgical treatments, and the influences of laser beam irradiation on bactericidal effect have been investigated. However, most of the work has been performed by irradiating to an agar plate with the colony of bacteria, and very few studies have been reported on the physical mechanism of bactericidal effects induced by laser beam irradiation. This paper deals with the measurement of dynamic stress induced in extracted human enamel by irradiation with Nd:YAG laser beams. Laser beams can be delivered to the enamel surface through a quartz optical fiber. Dynamic stress induced in the specimen using elastic wave propagation in a cylindrical long bar made of aluminum alloy is measured. Laser induced stress intensity is evaluated from dynamic strain measured by small semiconductor strain gauges. Carbon powder and titanium dioxide powder were applied to the human enamel surface as absorbents. Additionally, the phenomenon of laser beam irradiation to the human enamel surface was observed with an ultrahigh speed video camera. Results showed that a plasma was generated on the enamel surface during laser beam irradiation, and the melted tissues were scattered in the vertical direction against the enamel surface with a mushroom-like wave. Averaged scattering velocity of the melted tissues was 25.2 m/s. Induced dynamic stress on the enamel surface increased with increasing laser energy in each absorbent. Induced dynamic stresses with titanium dioxide powder were superior to those with carbon powder. Induced dynamic stress was related to volume of prepared cavity, and induced stress for the removal of unit volume of human enamel was 0.03 Pa/mm 3.

Enhancement of conversion efficiency of extreme ultraviolet radiation from a liquid aqueous solution microjet target by use of dual laser pulses

NASA Astrophysics Data System (ADS)

Higashiguchi, Takeshi; Dojyo, Naoto; Hamada, Masaya; Kawasaki, Keita; Sasaki, Wataru; Kubodera, Shoichi

2006-03-01

We demonstrated a debris-free, efficient laser-produced plasma extreme ultraviolet (EUV) source by use of a regenerative liquid microjet target containing tin-dioxide (SnO II) nano-particles. By using a low SnO II concentration (6%) solution and dual laser pulses for the plasma control, we observed the EUV conversion efficiency of 1.2% with undetectable debris.

Fractional carbon dioxide laser for the treatment of facial atrophic acne scars: prospective clinical trial with short and long-term evaluation.

PubMed

Elcin, Gonca; Yalici-Armagan, Basak

2017-12-01

The aim of this study was to evaluate the efficacy and safety of fractional carbon dioxide laser for the treatment of acne scars. Thirty-one participants, 15 female and 16 male, whose mean age was 34.84 ± 10.94 years, were included in this prospective study. The study took place between 2012 and 2016. Participants were evaluated with the "ECCA Grading Scale" before the first session, 3 months (short-term evaluation) and 3 years after the last session (long-term evaluation). Participants received two or three treatment sessions at 4-week intervals, with a 10,600 nm fractional carbon dioxide laser with pulse energies ranging between 100 and 160 mJ, 120 spot type, 75-100 spot/cm 2 density, and 30 W power. Self-assessments by the participants were done 3 months and 3 years after the last session. The mean ECCA score was 107.90 ± 39.38 before the first session, and 82.17 ± 36.23 at the time of short-term evaluation (p = 0.000). The grade of improvement at the short-term evaluation was as follows: no improvement, mild, moderate, and significant improvement for 7 (22.6%), 11 (35.5%), 9 (29%), and 4 (12.9%) of the participants, respectively. Regarding self-assessments, 80.6 and 61.3% of the participants rated themselves as having at least mild improvement at the short-term and the long-term follow-up periods, respectively. The results of this study suggest that fractional carbon dioxide laser is an efficient treatment option for acne scars. Furthermore, self-assessment results show that more than half of the participants still experience at least mild improvement at the end of 3 years.

Compact, highly efficient, single-frequency 25W, 2051nm Tm fiber-based MOPA for CO2 trace-gas laser space transmitter

NASA Astrophysics Data System (ADS)

Engin, Doruk; Chuang, Ti; Litvinovitch, Slava; Storm, Mark

2017-08-01

Fibertek has developed and demonstrated an ideal high-power; low-risk; low-size, weight, and power (SWaP) 2051 nm laser design meeting the lidar requirements for satellite-based global measurement of carbon dioxide (CO2). The laser design provides a path to space for either a coherent lidar approach being developed by NASA Jet Propulsion Laboratory (JPL)1,2 or an Integrated Path Differential Lidar (IPDA) approach developed by Harris Corp using radio frequency (RF) modulation and being flown as part of a NASA Earth Venture Suborbital Mission—NASA's Atmospheric Carbon and Transport - America.3,4 The thulium (Tm) fiber laser amplifies a <500 kHz linewidth distributed feedback (DFB) laser up to 25 W average power in a polarization maintaining (PM) fiber. The design manages and suppresses all deleterious non-linear effects that can cause linewidth broadening or amplified spontaneous emission (ASE) and meets all lidar requirements. We believe the core laser components, architecture, and design margins can support a coherent or IPDA lidar 10-year space mission. With follow-on funding Fibertek can adapt an existing space-based Technology Readiness Level 6 (TRL-6), 20 W erbium fiber laser package for this Tm design and enable a near-term space mission with an electrical-to-optical (e-o) efficiency of <20%. A cladding-pumped PM Tm fiber-based amplifier optimized for high efficiency and high-power operation at 2051 nm is presented. The two-stage amplifier has been demonstrated to achieve 25 W average power and <16 dB polarization extinction ratio (PER) out of a single-mode PM fiber using a <500 kHz linewidth JPL DFB laser5-7 and 43 dB gain. The power amplifier's optical conversion efficiency is 53%. An internal efficiency of 58% is calculated after correcting for passive losses. The two-stage amplifier sustains its highly efficient operation for a temperature range of 5-40°C. The absence of stimulated Brillouin scattering (SBS) for the narrow linewidth amplification shows promise for further power scaling.

Efficient sintering of nanocrystalline titanium dioxide films for dye solar cells via raster scanning laser

NASA Astrophysics Data System (ADS)

Mincuzzi, Girolamo; Vesce, Luigi; Reale, Andrea; Di Carlo, Aldo; Brown, Thomas M.

2009-09-01

By identifying the right combination of laser parameters, in particular the integrated laser fluence Φ, we fabricated dye solar cells (DSCs) with UV laser-sintered TiO2 films exhibiting a power conversion efficiency η =5.2%, the highest reported for laser-sintered devices. η is dramatically affected by Φ and a clear trend is reported. Significantly, DSCs fabricated by raster scanning the laser beam to sinter the TiO2 films are made as efficient as those with oven-sintered ones. These results, confirmed on three batches of cells, demonstrate the remarkable potential (noncontact, local, low cost, rapid, selective, and scalable) of scanning laser processing applied to DSC technology.

TDLAS a laser diode sensor for the in situ monitoring of H2O, CO2 and their isotopes in the Martian atmosphere

NASA Astrophysics Data System (ADS)

Le Barbu, T.; Vinogradov, I.; Durry, G.; Korablev, O.; Chassefière, E.; Bertaux, J.-L.

2006-01-01

Within the framework of Pasteur-Exomars, we have proposed to measure in situ water vapor (H2O, HDO, H218O, H217O) and carbon dioxide (CO2, 13C16O2, 16O12C18O, 16O12C17O) isotopes and also CO, CH4 and N2O by absorption spectroscopy using near infrared laser diodes. The Service d’Aéronomie has a relevant experience in trace-gas detection with laser diodes. We have developed, with the support of the CNES and the CNRS, the SDLA diode laser spectrometer to measure in situ H2O (at 1.39 μm), CH4 (1.65 μm) and CO2 (at 1.60 μm) in the middle atmosphere from stratospheric balloons. The concentrations are obtained with a precision error of a few percent and with a high temporal resolution that ranges from 10 ms to 1 s. The developed laser probing technique should be also highly efficient to study the Martian atmosphere as there are much higher amounts of water vapor and carbon dioxide in the Martian atmosphere than in the lower stratosphere (H2O: 200 ppmv at 6 hPa on Mars, 5 ppmv at 10 hPa in the low stratosphere (LS); CO2 95% on Mars, 360 ppmv in the LS). Hence, we propose to adapt the laser probing technique to the Martian atmosphere. The main objectives are to determine water vapor and carbon dioxide fluxes and to study boundary layer properties. The sensor will provide in situ daily, diurnally resolved measurements of near-surface H2O and CO2 concentrations over seasonal time scales. The additional isotopic measurements will provide quantitative constraints on the evolution of atmospheric composition and on the history of water on Mars.

Breath Analysis Using Laser Spectroscopic Techniques: Breath Biomarkers, Spectral Fingerprints, and Detection Limits

PubMed Central

Wang, Chuji; Sahay, Peeyush

2009-01-01

Breath analysis, a promising new field of medicine and medical instrumentation, potentially offers noninvasive, real-time, and point-of-care (POC) disease diagnostics and metabolic status monitoring. Numerous breath biomarkers have been detected and quantified so far by using the GC-MS technique. Recent advances in laser spectroscopic techniques and laser sources have driven breath analysis to new heights, moving from laboratory research to commercial reality. Laser spectroscopic detection techniques not only have high-sensitivity and high-selectivity, as equivalently offered by the MS-based techniques, but also have the advantageous features of near real-time response, low instrument costs, and POC function. Of the approximately 35 established breath biomarkers, such as acetone, ammonia, carbon dioxide, ethane, methane, and nitric oxide, 14 species in exhaled human breath have been analyzed by high-sensitivity laser spectroscopic techniques, namely, tunable diode laser absorption spectroscopy (TDLAS), cavity ringdown spectroscopy (CRDS), integrated cavity output spectroscopy (ICOS), cavity enhanced absorption spectroscopy (CEAS), cavity leak-out spectroscopy (CALOS), photoacoustic spectroscopy (PAS), quartz-enhanced photoacoustic spectroscopy (QEPAS), and optical frequency comb cavity-enhanced absorption spectroscopy (OFC-CEAS). Spectral fingerprints of the measured biomarkers span from the UV to the mid-IR spectral regions and the detection limits achieved by the laser techniques range from parts per million to parts per billion levels. Sensors using the laser spectroscopic techniques for a few breath biomarkers, e.g., carbon dioxide, nitric oxide, etc. are commercially available. This review presents an update on the latest developments in laser-based breath analysis. PMID:22408503

Optimizing fluence and debridement effects on cutaneous resurfacing carbon dioxide laser surgery.

PubMed

Weisberg, N K; Kuo, T; Torkian, B; Reinisch, L; Ellis, D L

1998-10-01

To develop methods to compare carbon dioxide (CO2) resurfacing lasers, fluence, and debridement effects on tissue shrinkage and histological thermal denaturation. In vitro human or in vivo porcine skin samples received up to 5 passes with scanner or short-pulsed CO2 resurfacing lasers. Fluences ranging from 2.19 to 17.58 J/cm2 (scanner) and 1.11 to 5.56 J/cm2 (short pulsed) were used to determine each laser's threshold energy for clinical effect. Variable amounts of debridement were also studied. Tissue shrinkage was evaluated by using digital photography to measure linear distance change of the treated tissue. Tissue histological studies were evaluated using quantitative computer image analysis. Fluence-independent in vitro tissue shrinkage was seen with the scanned and short-pulsed lasers above threshold fluence levels of 5.9 and 2.5 J/cm2, respectively. Histologically, fluence-independent thermal depths of damage of 77 microns (scanner) and 25 microns (pulsed) were observed. Aggressive debridement of the tissue increased the shrinkage per pass of the laser, and decreased the fluence required for the threshold effect. In vivo experiments confirmed the in vitro results, although the in vivo threshold fluence level was slightly higher and the shrinkage obtained was slightly lower per pass. Our methods allow comparison of different resurfacing lasers' acute effects. We found equivalent laser tissue effects using lower fluences than those currently accepted clinically. This suggests that the morbidity associated with CO2 laser resurfacing may be minimized by lowering levels of tissue input energy and controlling for tissue debridement.

Comparison of electrically driven lasers for space power transmission

NASA Technical Reports Server (NTRS)

Deyoung, R. J.; Lee, J. H.; Williams, M. D.; Schuster, G.; Conway, E. J.

1988-01-01

High-power lasers in space could provide power for a variety of future missions such as spacecraft electric power requirements and laser propulsion. This study investigates four electrically pumped laser systems, all scaled to 1-MW laser output, that could provide power to spacecraft. The four laser systems are krypton fluoride, copper vapor, laser diode array, and carbon dioxide. Each system was powered by a large solar photovoltaic array which, in turn, provided power for the appropriate laser power conditioning subsystem. Each system was block-diagrammed, and the power and efficiency were found for each subsystem block component. The copper vapor system had the lowest system efficiency (6 percent). The CO2 laser was found to be the most readily scalable but has the disadvantage of long laser wavelength.

Carbon fuel cells with carbon corrosion suppression

DOEpatents

Cooper, John F [Oakland, CA

2012-04-10

An electrochemical cell apparatus that can operate as either a fuel cell or a battery includes a cathode compartment, an anode compartment operatively connected to the cathode compartment, and a carbon fuel cell section connected to the anode compartment and the cathode compartment. An effusion plate is operatively positioned adjacent the anode compartment or the cathode compartment. The effusion plate allows passage of carbon dioxide. Carbon dioxide exhaust channels are operatively positioned in the electrochemical cell to direct the carbon dioxide from the electrochemical cell.

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.

Mechanism of laser-induced stress relaxation in cartilage

NASA Astrophysics Data System (ADS)

Sobol, Emil N.; Sviridov, Alexander P.; Omelchenko, Alexander I.; Bagratashvili, Victor N.; Bagratashvili, Nodar V.; Popov, Vladimir K.

1997-06-01

The paper presents theoretical and experimental results allowing to discuss and understand the mechanism of stress relaxation and reshaping of cartilage under laser radiation. A carbon dioxide and a Holmium laser was used for treatment of rabbits and human cartilage. We measured temperature, stress, amplitude of oscillation by free and forced vibration, internal friction, and light scattering in the course of laser irradiation. Using experimental data and theoretical modeling of heat and mass transfer in cartilaginous tissue we estimated the values of transformation heat, diffusion coefficients and energy activation for water movement.

Performance of an exhaled nitric oxide and carbon dioxide sensor using quantum cascade laser-based integrated cavity output spectroscopy.

PubMed

McCurdy, Matthew R; Bakhirkin, Yury; Wysocki, Gerard; Tittel, Frank K

2007-01-01

Exhaled nitric oxide (NO) is an important biomarker in asthma and other respiratory disorders. The optical performance of a NOCO(2) sensor employing integrated cavity output spectroscopy (ICOS) with a quantum cascade laser operating at 5.22 microm capable of real-time NO and CO(2) measurements in a single breath cycle is reported. A NO noise-equivalent concentration of 0.4 ppb within a 1-sec integration time is achieved. The off-axis ICOS sensor performance is compared to a chemiluminescent NO analyzer and a nondispersive infrared (NDIR) CO(2) absorption capnograph. Differences between the gas analyzers are assessed by the Bland-Altman method to estimate the expected variability between the gas sensors. The off-axis ICOS sensor measurements are in good agreement with the data acquired with the two commercial gas analyzers. This work demonstrates the performance characteristics and merits of mid-infrared spectroscopy for exhaled breath analysis.

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

Development of Control System for Hydrolysis Crystallization Process

NASA Astrophysics Data System (ADS)

Wan, Feng; Shi, Xiao-Ming; Feng, Fang-Fang

2016-05-01

Sulfate method for producing titanium dioxide is commonly used in China, but the determination of crystallization time is artificially which leads to a big error and is harmful to the operators. In this paper a new method for determining crystallization time is proposed. The method adopts the red laser as the light source, uses the silicon photocell as reflection light receiving component, using optical fiber as the light transmission element, differential algorithm is adopted in the software to realize the determination of the crystallizing time. The experimental results show that the method can realize the determination of crystallization point automatically and accurately, can replace manual labor and protect the health of workers, can be applied to practice completely.

Efficient 1.6 Micron Laser Source for Methane DIAL

NASA Technical Reports Server (NTRS)

Shuman, Timothy; Burnham, Ralph; Nehrir, Amin R.; Ismail, Syed; Hair, Johnathan W.

2013-01-01

Methane is a potent greenhouse gas and on a per molecule basis has a warming influence 72 times that of carbon dioxide over a 20 year horizon. Therefore, it is important to look at near term radiative effects due to methane to develop mitigation strategies to counteract global warming trends via ground and airborne based measurements systems. These systems require the development of a time-resolved DIAL capability using a narrow-line laser source allowing observation of atmospheric methane on local, regional and global scales. In this work, a demonstrated and efficient nonlinear conversion scheme meeting the performance requirements of a deployable methane DIAL system is presented. By combining a single frequency 1064 nm pump source and a seeded KTP OPO more than 5 mJ of 1.6 µm pulse energy is generated with conversion efficiencies in excess of 20%. Even without active cavity control instrument limited linewidths (50 pm) were achieved with an estimated spectral purity of 95%. Tunable operation over 400 pm (limited by the tuning range of the seed laser) was also demonstrated. This source demonstrated the critical needs for a methane DIAL system motivating additional development of the technology.

From Rockets to Racecars

NASA Technical Reports Server (NTRS)

2005-01-01

NASA s Langley Research Center scientists developed a family of catalysts for low- temperature oxidation of carbon monoxide and other gases. The catalysts provide oxidation of both carbon monoxide and formaldehyde at room temperature without requiring any energy input, just a suitable flow of gas through them. Originally designed as part of an atmospheric satellite project, where the catalysts were intended to recycle and recapture carbon dioxide to enhance the operational life of carbon dioxide lasers, the entire system was made to be rugged, long-lived, and fail-safe. The low-temperature oxidation catalysts can be produced and coated onto various catalyst supports, including porous ceramic monoliths and beads, which means that they can be integrated into existing designs, made to fit in limited space, and fashioned into a variety of geometrically different products. Although the satellite project was never launched, the resulting catalysts are doing great things here on Earth, with current applications in the high-speed motor sports arena as air purifiers, so professional racecar drivers do not get carbon monoxide poisoning. Future benefits may extend even further.

JPRS Report. Science & Technology: Japan.

DTIC Science & Technology

1987-07-07

the mirror with this high reflectance is also provided with a function of cutting off return light. The method of cutting off return light which is...0.351 micron), far down from the planned level of 100 kJ, owing to a damage incurred in the laser glass by absorption and heating of a contaminant...a new project, is also underway, which involves a "two-laser method " wherein ions are produced by a carbon-dioxide laser and subseguently excited

Treatment of Carcinoma In Situ of the Glans Penis With Topical Imiquimod Followed by Carbon Dioxide Laser Excision.

PubMed

Torelli, Tullio; Catanzaro, Mario A; Nicolai, Nicola; Giannatempo, Patrizia; Necchi, Andrea; Raggi, Daniele; Paolini, Biagio; Colecchia, Maurizio; Piva, Luigi; Biasoni, Davide; Stagni, Silvia; Tesone, Antonio; Salvioni, Roberto

2017-06-01

Different approaches have been described in published studies for carcinoma in situ (CIS) of the glans penis (erythroplasia of Queyrat), including topical chemotherapy or immunotherapy and laser or surgical excision. We evaluated the efficacy of topical imiquimod (IQ) followed by carbon dioxide laser ablation of the lesion. From 2010 to 2015, 10 patients affected by CIS of the glans were treated by IQ, followed by carbon dioxide laser ablation. For every patient, we performed histologic examination before and after IQ. Local toxicity and adverse effects were recorded. After treatment, histologic examination showed no residual tumor in 6 patients (complete response [CR]), stable disease in 2 patients, and progressive disease in 2 patients. Those with a CR had human papillomavirus-related lesions, and they had no experienced relapses after a mean follow-up of 26 months. The 2 patients with progressive disease underwent total penectomy. All patients were alive at the last follow-up examination. All patients experienced a mild local toxicity (burning erythema) but no major adverse effects. Local treatment with IQ for glans CIS is effective mainly for human papillomavirus-related lesions. The present study is the first to record the histologic examination findings before and after IQ treatment. The small number of patients, owing to the rarity of this disease, was the main limitation of the present study. IQ must be used carefully, and a close follow-up protocol is mandatory because of the lack of long-term efficacy data. Copyright © 2017 Elsevier Inc. All rights reserved.

A Lithography-Free and Field-Programmable Photonic Metacanvas.

PubMed

Dong, Kaichen; Hong, Sukjoon; Deng, Yang; Ma, He; Li, Jiachen; Wang, Xi; Yeo, Junyeob; Wang, Letian; Lou, Shuai; Tom, Kyle B; Liu, Kai; You, Zheng; Wei, Yang; Grigoropoulos, Costas P; Yao, Jie; Wu, Junqiao

2018-02-01

The unique correspondence between mathematical operators and photonic elements in wave optics enables quantitative analysis of light manipulation with individual optical devices. Phase-transition materials are able to provide real-time reconfigurability of these devices, which would create new optical functionalities via (re)compilation of photonic operators, as those achieved in other fields such as field-programmable gate arrays (FPGA). Here, by exploiting the hysteretic phase transition of vanadium dioxide, an all-solid, rewritable metacanvas on which nearly arbitrary photonic devices can be rapidly and repeatedly written and erased is presented. The writing is performed with a low-power laser and the entire process stays below 90 °C. Using the metacanvas, dynamic manipulation of optical waves is demonstrated for light propagation, polarization, and reconstruction. The metacanvas supports physical (re)compilation of photonic operators akin to that of FPGA, opening up possibilities where photonic elements can be field programmed to deliver complex, system-level functionalities. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

40 CFR 62.15175 - What continuous emission monitoring systems must I install for gaseous pollutants?

Code of Federal Regulations, 2013 CFR

2013-07-01

... part 60. (c) You must monitor the oxygen (or carbon dioxide) concentration at each location where you..., maintain, and operate continuous emission monitoring systems for oxygen (or carbon dioxide), sulfur dioxide, and carbon monoxide. If you operate a Class I municipal waste combustion unit, also install, calibrate...

40 CFR 62.15175 - What continuous emission monitoring systems must I install for gaseous pollutants?

Code of Federal Regulations, 2014 CFR

2014-07-01

... part 60. (c) You must monitor the oxygen (or carbon dioxide) concentration at each location where you..., maintain, and operate continuous emission monitoring systems for oxygen (or carbon dioxide), sulfur dioxide, and carbon monoxide. If you operate a Class I municipal waste combustion unit, also install, calibrate...

40 CFR 62.15175 - What continuous emission monitoring systems must I install for gaseous pollutants?

Code of Federal Regulations, 2012 CFR

2012-07-01

... part 60. (c) You must monitor the oxygen (or carbon dioxide) concentration at each location where you..., maintain, and operate continuous emission monitoring systems for oxygen (or carbon dioxide), sulfur dioxide, and carbon monoxide. If you operate a Class I municipal waste combustion unit, also install, calibrate...

Extensive tissue damage of bovine ovaries after bipolar ovarian drilling compared to monopolar electrocoagulation or carbon dioxide laser.

PubMed

Hendriks, Marja-Liisa; van der Valk, Paul; Lambalk, Cornelis B; Broeckaert, Mark A M; Homburg, Roy; Hompes, Peter G A

2010-02-01

To evaluate the size of ovarian damage caused by ovarian drilling in polycystic ovary syndrome, the amount of inflicted damage was assessed for the most frequently used ovarian drilling techniques. Experimental prospective design. University clinic. Six fresh bovine ovaries per technique. Carbon dioxide (CO(2)) laser, monopolar electrocoagulation, and bipolar electrocoagulation were used for in vitro ovarian drilling. Amount of inflicted ovarian damage per procedure. Bipolar electrocoagulation resulted in significantly more destruction per burn than the CO(2) laser and monopolar electrocoagulation (287.6 versus 24.0 and 70.0 mm(3), respectively). The damage found per lesion was multiplied by the regularly applied number of punctures per procedure in daily practice (based on the literature). Again, the bipolar electrocoagulation resulted in significantly more tissue damage than the CO(2) laser and monopolar coagulation (2,876 versus 599 and 700 mm(3), respectively). Ovarian drilling, especially bipolar electrocoagulation, causes extensive destruction of the ovary. Given the same clinical effectiveness of the various procedures, it is essential to use the lowest possible dose that works; thus, the first choice should be CO(2) laser or monopolar electrocoagulation. Copyright 2010 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

An optical method for carbon dioxide isotopes and mole fractions in small gas samples: tracing microbial respiration from soil, litter, and lignin.

Treesearch

Steven J. Hall; Wenjuan Huang; Kenneth Hammel

2017-01-01

RATIONALE: Carbon dioxide isotope (Δ13C value) measurements enable quantification of the sources of soil microbial respiration, thus informing ecosystem C dynamics. Tunable diode lasers (TDLs) can precisely measure CO2 isotopes at low cost and high throughput, but are seldom used for small samples (≤5 mL). We developed a...

Studies on the mechanism of printing film-coated tablets containing titanium dioxide in the film by using UV laser irradiation.

PubMed

Kato, Yoshiteru; Nakashima, Yasuhiko; Shino, Naoki; Sasaki, Koichi; Hosokawa, Akihiro; Ishihara, Hiroshi

2010-04-01

The purpose of this article is to study a detailed mechanism of printing when film-coated tablets were irradiated by UV laser at a wavelength of 355 nm. Hydroxypropylmethylcellulose (HPMC) film containing titanium dioxide (TiO(2)) and the film not containing TiO(2) and TiO(2) powder were lirradiated by the UV laser and estimated by the morphological observation by zoom stereo microscope, thermogravimetric analysis (TGA), total color difference (dE), X-ray powder diffraction (XRD), and dispersive Raman microscopy. In the case of the film containing TiO(2), the film showed a visible change in its color from white to gray by the UV laser irradiation. By zoom stereo microscope, it was found that the entire UV laser-irradiated area was not grayed uniformly, but many black particles, whose diameter was about 2 microm, were observed on the film. When TiO(2) powder was irradiated by the UV laser, a visible change in its color from white to gray was observed similar to the case of the film containing TiO(2). There were many black particles locally in the UV laser-treated TiO(2) powder by the morphological observation, and these black particles, agglomerates of the grayed oxygen-defected TiO(2), were associated with the visible change of the TiO(2). It was found that the film-coated tablets were printed utilizing the formation of the black particles by the agglomeration of the grayed oxygen-defected TiO(2) by the UV laser irradiation.

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

Fractional carbon dioxide (CO2) laser combined with topical tretinoin for the treatment of different forms of cystic acne.

PubMed

Pestoni Porvén, Carmela; Vieira Dos Santos, Vanessa; Del Pozo Losada, Jesus

2017-12-01

Nodulocystic acne is prone to scarring and difficult to treat with treatments other than oral isotretinoin. The aim of this article is to discuss the role of a single session of a fractional carbon dioxide (CO 2 ) laser combined with a topical treatment with a tretinoin and antibiotic gel for a month as a successful treatment to improve nodulocystic acne and chronic microcystic acne. Two cases were involved: the first with nodulocystic acne lesions that persisted after oral retinoids and the second with chronic microcystic acne resistant to topical treatments. After only one session of treatment with the CO 2 laser and the topical treatment, a complete healing of the nodulocystic acne lesions was observed with minimal secondary effects. The microcystic acne showed great improvement. No other topical or oral treatment was needed. This treatment could be a safe and effective treatment for nodulocystic acne lesions and microcystic acne when other treatments fail. More studies should be performed to confirm our results.

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.

Recent advances in the study of the UO2-PuO2 phase diagram at high temperatures

NASA Astrophysics Data System (ADS)

Böhler, R.; Welland, M. J.; Prieur, D.; Cakir, P.; Vitova, T.; Pruessmann, T.; Pidchenko, I.; Hennig, C.; Guéneau, C.; Konings, R. J. M.; Manara, D.

2014-05-01

Recently, novel container-less laser heating experimental data have been published on the melting behaviour of pure PuO2 and PuO2-rich compositions in the uranium dioxide-plutonium dioxide system. Such data showed that previous data obtained by more traditional furnace heating techniques were affected by extensive interaction between the sample and its containment. It is therefore paramount to check whether data so far used by nuclear engineers for the uranium-rich side of the pseudo-binary dioxide system can be confirmed or not. In the present work, new data are presented both in the UO2-rich part of the phase diagram, most interesting for the uranium-plutonium dioxide based nuclear fuel safety, and in the PuO2 side. The new results confirm earlier furnace heating data in the uranium-dioxide rich part of the phase diagram, and more recent laser-heating data in the plutonium-dioxide side of the system. As a consequence, it is also confirmed that a minimum melting point must exist in the UO2-PuO2 system, at a composition between x(PuO2) = 0.4 and x(PuO2) = 0.7 and 2900 K ⩽ T ⩽ 3000 K. Taking into account that, especially at high temperature, oxygen chemistry has an effect on the reported phase boundary uncertainties, the current results should be projected in the ternary U-Pu-O system. This aspect has been extensively studied here by X-ray diffraction and X-ray absorption spectroscopy. The current results suggest that uncertainty bands related to oxygen behaviour in the equilibria between condensed phases and gas should not significantly affect the qualitative trend of the current solid-liquid phase boundaries.

Histologic effects of resurfacing lasers.

PubMed

Freedman, Joshua R; Greene, Ryan M; Green, Jeremy B

2014-02-01

By utilizing resurfacing lasers, physicians can significantly improve the appearance of sun-damaged skin, scars, and more. The carbon dioxide and erbium:yttrium-aluminum-garnet lasers were the first ablative resurfacing lasers to offer impressive results although these earlier treatments were associated with significant downtime. Later, nonablative resurfacing lasers such as the neodymium:yttrium-aluminum-garnet laser proved effective, after a series of treatments with less downtime, but with more modest results. The theory of fractional photothermolysis has revolutionized resurfacing laser technology by increasing the safety profile of the devices while delivering clinical efficacy. A review of the histologic and molecular consequences of the resurfacing laser-tissue interaction allows for a better understanding of the devices and their clinical effects. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Preparation of platinum modified titanium dioxide nanoparticles with the use of laser ablation in water.

PubMed

Siuzdak, K; Sawczak, M; Klein, M; Nowaczyk, G; Jurga, S; Cenian, A

2014-08-07

We report on the preparation method of nanocrystalline titanium dioxide modified with platinum by using nanosecond laser ablation in liquid (LAL). Titania in the form of anatase crystals has been prepared in a two-stage process. Initially, irradiation by laser beam of a titanium metal plate fixed in a glass container filled with deionized water was conducted. After that, the ablation process was continued, with the use of a platinum target placed in a freshly obtained titania colloid. In this work, characterization of the obtained nanoparticles, based on spectroscopic techniques--Raman, X-ray photoelectron and UV-vis reflectance spectroscopy--is given. High resolution transmission electron microscopy was used to describe particle morphology. On the basis of photocatalytic studies we observed the rate of degradation process of methylene blue (MB) (a model organic pollution) in the presence of Pt modified titania in comparison to pure TiO2--as a reference case. Physical and chemical mechanisms of the formation of platinum modified titania are also discussed here. Stable colloidal suspensions containing Pt modified titanium dioxide crystalline anatase particles show an almost perfect spherical shape with diameters ranging from 5 to 30 nm. The TiO2 nanoparticles decorated with platinum exhibit much higher (up to 30%) photocatalytic activity towards the degradation of MB under UV illumination than pure titania.

Optical Multi-Gas Monitor Technology Demonstration on the International Space Station

NASA Technical Reports Server (NTRS)

Pilgrim, Jeffrey S.; Wood, William R.; Casias, Miguel E.; Vakhtin, Andrei B,; Johnson, Michael D.; Mudgett, Paul D.

2014-01-01

There are a variety of both portable and fixed gas monitors onboard the International Space Station (ISS). Devices range from rack-mounted mass spectrometers to hand-held electrochemical sensors. An optical Multi-Gas Monitor has been developed as an ISS Technology Demonstration to evaluate long-term continuous measurement of 4 gases. Based on tunable diode laser spectroscopy, this technology offers unprecedented selectivity, concentration range, precision, and calibration stability. The monitor utilizes the combination of high performance laser absorption spectroscopy with a rugged optical path length enhancement cell that is nearly impossible to misalign. The enhancement cell serves simultaneously as the measurement sampling cell for multiple laser channels operating within a common measurement volume. Four laser diode based detection channels allow quantitative determination of ISS cabin concentrations of water vapor (humidity), carbon dioxide, ammonia and oxygen. Each channel utilizes a separate vertical cavity surface emitting laser (VCSEL) at a different wavelength. In addition to measuring major air constituents in their relevant ranges, the multiple gas monitor provides real time quantitative gaseous ammonia measurements between 5 and 20,000 parts-per-million (ppm). A small ventilation fan draws air with no pumps or valves into the enclosure in which analysis occurs. Power draw is only about 3 W from USB sources when installed in Nanoracks or when connected to 28V source from any EXPRESS rack interface. Internal battery power can run the sensor for over 20 hours during portable operation. The sensor is controlled digitally with an FPGA/microcontroller architecture that stores data internally while displaying running average measurements on an LCD screen and interfacing with the rack or laptop via USB. Design, construction and certification of the Multi-Gas Monitor were a joint effort between Vista Photonics, Nanoracks and NASA-Johnson Space Center (JSC). Vista Photonics developed the core technology and built the sensor. Nanoracks designed, constructed the enclosure, interfaces, and battery power management circuitry, integrated all subsystems into the enclosure, and then managed the certification tests, documentation and manifesting. The unit was calibrated in the JSC Toxicology Laboratory. The Multi-Gas Monitor is manifested to fly as a technology demonstration to the ISS in November 2013 and will operate for at least 6 months with data sent to the ground for evaluation. The primary goal is to demonstrate long term interference free operation in the real spacecraft environment.

Laser machining of southern pine

Treesearch

C. W. McMillin; J. E. Harry

1971-01-01

When cutting with an air-jet-assisted carbon-dioxide laser of 240 watts output power, maximum feed speed at the point of full penetration of the beam decreased with increasing workpiece thickness in both wet and dry samples; the trend was curvilinear. Feed speeds averaged 99.1 and 14.6 inches per minute for samples 0.25 and 1.00 inch thick, respectively. Somewhat...

Astronomical masers and lasers

NASA Astrophysics Data System (ADS)

Townes, C. H.

1997-12-01

A brief account is given of the discovery of the astronomical maser and laser effects in OH radicals and in molecules of water (H2O), carbon monoxide and dioxide (CO and CO2), ammonia (NH3), methyl alcohol (CH3OH), formaldehyde (CH2O), and silicon oxide (SiO). A detailed table is given of all the currently known molecular stimulated-emission lines.

Evaluation of Carbon Dioxide Laser in the Treatment of Epidermal Nevi.

PubMed

Bhat, Yasmeen Jabeen; Hassan, Iffat; Sajad, Peerzada; Yaseen, Atiya; Mubashir, Syed; Akhter, Saniya; Wani, Roohi

2016-01-01

Epidermal naevi are benign hamartomatous growths of the skin which are generally asymptomatic with a benign course but are cosmetically disagreeable. Topical treatments such as steroids, calcipotriol, 5 fluorouracil, podophyllin, retinoids and cryotherapy are ineffective and surgical excision results in scar formation. Therapy is often challenging. To study the response of carbon dioxide (CO 2 ) laser in the management of epidermal naevi. We conducted a study of CO 2 laser treatment on 15 patients of epidermal naevi, eight with verrucous epidermal naevi and seven with sebaceous naevi. A thorough history and examination was done to rule out any epidermal naevus syndrome. The diagnosis was confirmed by histopathology. The number of treatment sessions varied from 1 to 8. Response was excellent (>90% reduction in lesion size) in three patients, very good (>75% reduction) in five, good (>50% reduction in lesion size) in five and poor (<50% reduction in lesion size) in two patients. The side effects were hyperpigmentation and scarring. Long-term follow-up over a period of 10 months showed a recurrence rate of 20%. We conclude that CO 2 laser treatment might be an effective option with long-term safety, minimal discomfort and rapid recovery.

Carbon dioxide (CO2) laser third eyelid excision: surgical description and report of 7 cases.

PubMed

Dees, Dustin D; Knollinger, Amy M; MacLaren, Nicole E

2015-09-01

To describe a novel technique for third eyelid (TEL) excision using a carbon dioxide (CO2) laser. Prospective. The procedure was performed on six canine patients and one feline patient. The laser was set to 6 Watts (W) of power and a linear continuous setting. Forceps were used to elevate the TEL and, with a protective shield covering the cornea, the base was cut and cauterized simultaneously. Minimal to no hemorrhage was observed, and the conjunctiva was left to heal by second intention. Seven patients underwent unilateral surgical TEL excision. All patients had suspected neoplasms affecting either the glandular tissues or conjunctival surfaces of the TEL. Clean surgical margins were achieved in all but one patient. All surgical sites were considered healed by 14 days showing mild-to-moderate conjunctival hyperemia and accumulation of mucoid discharge at the ventronasal fornix. One patient experienced postoperative keratoconjunctivitis sicca. Prolapse of orbital fat was not observed in any patient. Use of CO2 laser appears to be an efficient and effective means for surgical third eyelid removal with excellent postoperative comfort and minimal complications. © 2014 American College of Veterinary Ophthalmologists.

Favre-Racouchot syndrome: a novel two-step treatment approach using the carbon dioxide laser.

PubMed

Rai, S; Madan, V; August, P J; Ferguson, J E

2014-03-01

Favre-Racouchot syndrome (FRS) is both disfiguring and difficult to treat. Available medical and surgical therapies are of variable efficacy. Most treatments do not achieve complete resolution and do not show maintenance of therapeutic response. To assess the response to a novel two-step treatment using the CO2 laser in patients with FRS. Seven patients with FRS were treated with the CO2 laser in resurfacing mode with manual expression of comedones under infiltrative local anaesthesia. The procedure was completed in one treatment session lasting 30 min and the wound was left to heal by secondary intention. A topical antibiotic was applied to treated areas, which were covered with a nonadherent dressing. All patients were assessed 3 months postoperatively by the operating laser surgeon and a visual assessment of clinical response to treatment in comparison with pretreatment photographs was made. Patient satisfaction was also recorded. All patients achieved complete resolution of FRS. The follow-up duration for our cohort ranged from 8 months to 3 years. Two patients required further treatment within a 2-3-year period from initial treatment. Disease relapse was noted over 1 year after the primary treatment; both these cases were smokers and repeat treatment with similar laser parameters maintained reproducible results. Our longest disease-free follow-up duration was 3 years postprimary treatment. The laser surgeons and patients reported high levels of therapeutic benefit and satisfaction with the results. This two-step treatment of FRS (CO2 laser resurfacing and manual pressure-induced expression of comedones) is an effective and durable treatment for FRS with an excellent cosmetic outcome. Long-term follow-up beyond 3 years is planned to determine whether later recurrence occurs with this technique. © 2013 British Association of Dermatologists.

CO2 laser in treatment of condylomata acuminata of male reproductive organs

NASA Astrophysics Data System (ADS)

Wozniak, Jakub; Opala, Tomasz; Pisarska-Krawczyk, Magdalena; Wilczak, Maciej; Pisarski, Tadeusz

1996-03-01

The results of laser therapy in the treatment of condylomata acuminata of male reproductive organs are reported. Between November 1991 and February 1995 in the Department of Reproduction, Institute of Gynecology and Obstetrics, Karol Marcinkowski University School of Medical Sciences, Poznan in 28 patients with condylomatous changes of reproductive organs carbon-dioxide laser therapy under colposcopic control was done. In 24 of them the healing was achieved. In four patients second laser therapy was done. All patients are still under control in the Department of Reproduction and there was no recurrence diagnosed.

Optical Emission Studies of Copper Plasma Induced Using Infrared Transversely Excited Atmospheric (IR TEA) Carbon Dioxide Laser Pulses.

PubMed

Momcilovic, Milos; Kuzmanovic, Miroslav; Rankovic, Dragan; Ciganovic, Jovan; Stoiljkovic, Milovan; Savovic, Jelena; Trtica, Milan

2015-04-01

Spatially resolved, time-integrated optical emission spectroscopy was applied for investigation of copper plasma produced by a nanosecond infrared (IR) transversely excited atmospheric (TEA) CO2 laser, operating at 10.6 μm. The effect of surrounding air pressure, in the pressure range 0.1 to 1013 mbar, on plasma formation and its characteristics was investigated. A linear dependence of intensity threshold for plasma formation on logarithm of air pressure was found. Lowering of the air pressure reduces the extent of gas breakdown, enabling better laser-target coupling and thus increases ablation. Optimum air pressure for target plasma formation was 0.1 mbar. Under that pressure, the induced plasma consisted of two clearly distinguished and spatially separated regions. The maximum intensity of emission, with sharp and well-resolved spectral lines and negligibly low background emission, was obtained from a plasma zone 8 mm from the target surface. The estimated excitation temperature in this zone was around 7000 K. The favorable signal to background ratio obtained in this plasma region indicates possible analytical application of TEA CO2 laser produced copper plasma. Detection limits of trace elements present in the Cu sample were on the order of 10 ppm (parts per million). Time-resolved measurements of spatially selected plasma zones were used to find a correlation between the observed spatial position and time delay.

[The study of CO2 cavity enhanced absorption and highly sensitive absorption spectroscopy].

PubMed

Pei, Shi-Xin; Gao, Xiao-Ming; Cui, Fen-Ping; Huang, Wei; Shao, Jie; Fan, Hong; Zhang, Wei-Jun

2005-12-01

Cavity enhanced absorption spectroscopy (CEAS) is a new spectral technology that is based on the cavity ring down absorption spectroscopy. In the present paper, a DFB encapsulation narrow line width tunable diode laser (TDL) was used as the light source. At the center output, the TDL radiation wavelength was 1.573 microm, and an optical cavity, which consisted of two high reflectivity mirrors (near 1.573 microm, the mirror reflectivity was about 0.994%), was used as a sample cell. A wavemeter was used to record the accurate frequency of the laser radiation. In the experiment, the method of scanning the optical cavity to change the cavity mode was used, when the laser frequency was coincident with one of the cavity mode; the laser radiation was coupled into the optical cavity and the detector could receive the light signals that escaped the optical cavity. As a result, the absorption spectrum of carbon dioxide weak absorption at low pressure was obtained with an absorption intensity of 1.816 x 10(-23) cm(-1) x (molecule x cm(-2)(-1) in a sample cell with a length of only 33.5 cm. An absorption sensitivity of about 3.62 x 10(-7) cm(-1) has been achieved. The experiment result indicated that the cavity enhanced absorption spectroscopy has the advantage of high sensivity, simple experimental setup, and easy operation.

Detection of gain enhancement in laser-induced fluorescence of rhodamine B lasing dye by silicon dioxide nanostructures-coated cavity

NASA Astrophysics Data System (ADS)

Al-Tameemi, Mohammed N. A.

2018-03-01

In this work, nanostructured silicon dioxide films are deposited by closed-field unbalanced direct-current (DC) reactive magnetron sputtering technique on two sides of quartz cells containing rhodamine B dye dissolved in ethanol with 10‒5 M concentration as a random gain medium. The preparation conditions are optimized to prepare highly pure SiO2 nanostructures with a minimum particle size of about 20 nm. The effect of SiO2 films as external cavity for the random gain medium is determined by the laser-induced fluorescence of this medium, and an increase of about 200% in intensity is observed after the deposition of nanostructured SiO2 thin films on two sides of the dye cell.

Evaluation of the Effect of Water Vapor On the Performance of NASA's NMRO Catalysts for Carbon Monoxide Oxidation

NASA Technical Reports Server (NTRS)

Akyurtlu, Ates; Akyurtlu, Jale F.; Ammons, Vaughnery; Battle, Taikelia; Gay, Amy; Bray, Kyle; Washington, Boe; Schryer, David (Technical Monitor); Jordan, Jeff (Technical Monitor)

2002-01-01

The Noble Metal Reducible Oxide (NMRO) catalysts for the low temperature oxidation of carbon monoxide were developed by NASA for the reoxidation of carbon monoxide which forms by the dissociation of carbon dioxide during the operation of sealed carbon dioxide lasers. The NMRO catalyst, which consists of a noble metal in conjunction with a reducible metal oxide, was evaluated under conditions that will be encountered in a CO2 laser operation, namely temperatures in the range 298 to 373 K and no significant reaction gas components other than CO, CO2 and O2. The NMRO catalysts may have significant potential for spin-off applications such as the prevention of carbon monoxide build-up in closed spaces as in space vehicle cabins or submarines, and the elimination of the cold start-up problem of automobile exhaust catalysts. The most significant difference in the conditions of these possible future applications is the high moisture content of the gases to be processed. Lack of understanding of the effects of water vapor and high temperature on catalyst activity and operation for extended periods are currently the main stumbling blocks for the transfer of this NASA technology to be used for commercial purposes. In the original proposal the following objectives were stated: To obtain experimental data on the adsorption, desorption and reaction characteristics of CO and CO2 the catalysts under high moisture conditions; to collect evidence on the presence of carbonate and hydroxyl surface species and their involvement in the CO oxidation mechanism; and to model the reaction system using a Monte-Carlo simulation to gain insight on the various steps involved. After the work has commenced the NASA technical monitor Mr. David Scheyer informed us that there was increased interest in the possible use of the NMRO catalysts as automobile exhaust catalysts and therefore NASA wanted to know whether the catalysts can operate at high temperatures as well as with high moisture gases. At that meeting it was decided that investigation of the high temperature performance of the NMRO catalysts should be given priority and replace the Monte-Carlo simulation objective. As a result, the modified objectives of the investigation were taken as the investigation of the high-temperature activity of the NMRO catalysts, and the effect of water vapor on the performance of these catalysts.

PROCESS FOR COOLING A NUCLEAR REACTOR

DOEpatents

Borst, L.B.

1962-12-11

This patent relates to the operation of a reactor cooled by liquid sulfur dioxide. According to the invention the pressure on the sulfur dioxide in the reactor is maintained at least at the critical pressure of the sulfur dioxide. Heating the sulfur dioxide to its critical temperature results in vaporization of the sulfur dioxide without boiling. (AEC)

The carbon footprint of Australian ambulance operations.

PubMed

Brown, Lawrence H; Canyon, Deon V; Buettner, Petra G; Crawford, J Mac; Judd, Jenni

2012-12-01

To determine the greenhouse gas emissions associated with the energy consumption of Australian ambulance operations, and to identify the predominant energy sources that contribute to those emissions. A two-phase study of operational and financial data from a convenience sample of Australian ambulance operations to inventory their energy consumption and greenhouse gas emissions for 1 year. State- and territory-based ambulance systems serving 58% of Australia's population and performing 59% of Australia's ambulance responses provided data for the study. Emissions for the participating systems totalled 67 390 metric tons of carbon dioxide equivalents. For ground ambulance operations, emissions averaged 22 kg of carbon dioxide equivalents per ambulance response, 30 kg of carbon dioxide equivalents per patient transport and 3 kg of carbon dioxide equivalents per capita. Vehicle fuels accounted for 58% of the emissions from ground ambulance operations, with the remainder primarily attributable to electricity consumption. Emissions from air ambulance transport were nearly 200 times those for ground ambulance transport. On a national level, emissions from Australian ambulance operations are estimated to be between 110 000 and 120 000 tons of carbon dioxide equivalents each year. Vehicle fuels are the primary source of emissions for ground ambulance operations. Emissions from air ambulance transport are substantially higher than those for ground ambulance transport. © 2012 The Authors. EMA © 2012 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine.

Two Micron Laser Technology Advancements at NASA Langley Research Center

NASA Technical Reports Server (NTRS)

Singh, Upendra N.

2010-01-01

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

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.

Molecular effects of fractional carbon dioxide laser resurfacing on photodamaged human skin.

PubMed

Reilly, Michael J; Cohen, Marc; Hokugo, Akishige; Keller, Gregory S

2010-01-01

Objective To elucidate the sequential changes in protein expression that play a role in the clinically beneficial results seen with fractional carbon dioxide (CO(2)) laser resurfacing of the face and neck. Methods Nine healthy volunteers were recruited for participation from the senior author's facial plastic surgery practice. After informed consent was obtained, each volunteer underwent a 2-mm punch biopsy from a discrete area of infra-auricular neck skin prior to laser treatment. Patients then immediately underwent laser resurfacing of photodamaged face and neck skin at a minimal dose (30 W for 0.1 second) with the Pixel Perfect fractional CO(2) laser. On completion of the treatment, another biopsy specimen was taken adjacent to the first site. Additional biopsy specimens were subsequently taken from adjacent skin at 2 of 3 time points (day 7, day 14, or day 21). RNA was extracted from the specimens, and reverse transcriptase-polymerase chain reaction and protein microarray analysis were performed. Comparisons were then made between time points using pairwise comparison testing. Results We found statistically significant changes in the gene expression of several matrix metalloproteinases (MMPs). The data demonstrate a consistent up-regulation of MMPs 1, 3, 9, and 13, all of which have been previously reported for fully ablative CO(2) laser resurfacing. There was also a statistically significant increase in MMP-10 and MMP-11 levels in this data set. Conclusion This study suggests that the molecular mechanisms of action are similar for both fractional and fully ablative CO(2) laser resurfacing.

Utilizing Diffusion Theory to predict carbon dioxide concentration in an indoor environment

NASA Astrophysics Data System (ADS)

Kramer, Andrew R.

This research details a new method of relating sources of carbon dioxide to carbon dioxide concentration in a room operating in a reduced ventilation mode by utilizing Diffusion Theory. The theoretical basis of this research involved solving Fick's Second Law of Diffusion in spherical coordinates for a source of carbon dioxide flowing at a constant rate and located in the center of an impermeable spherical boundary. The solution was developed using a Laplace Transformation. A spherical diffusion test chamber was constructed and used to validate and benchmark the developed theory. The method was benchmarked by using Dispersion Coefficients for large carbon dioxide flow rates due to diffusion induced convection. The theoretical model was adapted to model a room operating with restricted ventilation in the presence of a known, constant source of carbon dioxide. The room was modeled as a sphere of volume equal to the room and utilized a Dispersion Coefficient that is consistent with published values. The developed Diffusion Model successfully predicted the spatial concentration of carbon dioxide in a room operating in a reduced ventilation mode in the presence of a source of carbon dioxide. The flow rates of carbon dioxide that were used in the room are comparable to the average flow rate of carbon dioxide from a person during quiet breathing, also known as the Tidal Breathing. This indicates the Diffusion Model developed from this research has the potential to correlate carbon dioxide concentration with static occupancy levels which can lead to energy savings through a reduction in air exchange rates when low occupancy is detected.

40 CFR 86.524-78 - Carbon dioxide analyzer calibration.

Code of Federal Regulations, 2012 CFR

2012-07-01

... operation. Adjust the analyzer to optimize performance. (2) Zero the carbon dioxide analyzer with either zero grade air or zero grade nitrogen. (3) Calibrate on each normally used operating range with carbon...

40 CFR 86.524-78 - Carbon dioxide analyzer calibration.

Code of Federal Regulations, 2013 CFR

2013-07-01

... operation. Adjust the analyzer to optimize performance. (2) Zero the carbon dioxide analyzer with either zero grade air or zero grade nitrogen. (3) Calibrate on each normally used operating range with carbon...

40 CFR 86.524-78 - Carbon dioxide analyzer calibration.

Code of Federal Regulations, 2014 CFR

2014-07-01

... operation. Adjust the analyzer to optimize performance. (2) Zero the carbon dioxide analyzer with either zero grade air or zero grade nitrogen. (3) Calibrate on each normally used operating range with carbon...

The role of transforming growth factor β1 in fractional laser resurfacing with a carbon dioxide laser.

PubMed

Jiang, Xia; Ge, Hongmei; Zhou, Chuanqing; Chai, Xinyu; Deng, Hui

2014-03-01

The aim of this study was to investigate the role of transforming growth factor β1 in mechanisms of cutaneous remodeling induced by fractional carbon dioxide laser treatment. The dorsal skin of Kunming mice was exposed to a single-pass fractional CO2 laser treatment. Biopsies were taken at 1 h and at 1, 3, 7, 14, 21, 28, and 56 days after treatment. Transforming growth factor (TGF) β1 expression in skin samples was evaluated by ELISA, dermal thickness by hematoxylin-eosin staining, collagen and elastic fibers by Ponceau S and Victoria blue double staining, and types I and III collagens by ELISA. The level of TGF β1 in the laser-treated areas of skin was significantly increased compared with that in the control areas on days 1 (p < 0.05), 3 (p < 0.01), and 7 (p < 0.05) and then decreased by day 14 after treatment, at which time it had returned to the baseline level. Dermal thickness and the amount of type I collagen of the skin of the laser-treated areas had increased significantly (p < 0.05) compared with that in control areas on days 28 and 56. Fibroblast proliferation showed a positive correlation with TGF β1 expression during the early stages (r = 0.789, p < 0.01), and there was a negative correlation between the level of TGF β1 and type I collagen in the late stages, after laser treatment (r = -0.546, p < 0.05). TGF β1 appears to be an important factor in fractional laser resurfacing.

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

PubMed Central

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

2016-01-01

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

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

PubMed

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

2016-06-01

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

Fractional Carbon Dioxide Laser and its Combination with Subcision in Improving Atrophic Acne Scars.

PubMed

Nilforoushzadeh, Mohammad Ali; Faghihi, Gita; Jaffary, Fariba; Haftbaradaran, Elaheh; Hoseini, Sayed Mohsen; Mazaheri, Nafiseh

2017-01-01

Acne is a very common skin disease in which scars are seen in 95% of the patients. Although numerous treatments have been recommended, researchers are still searching for a single modality to treat the complication due to its variety in shape and depth. We compared the effects of fractional carbon dioxide (CO 2 ) laser alone and in combination with subcision in the treatment of atrophic acne scars. This clinical trial study was performed in Skin Diseases and Leishmaniasis Research Center (Isfahan, Iran) during 2011-2012. Eligible patients with atrophic acne scars were treated with fractional CO 2 laser alone (five sessions with 3-week interval) on the right side of the face and fractional CO 2 laser plus subcision (one session using both with four sessions of fractional CO 2 laser, with 3-week interval) on the left side. The subjects were visited 1, 2, and 6 months after the treatment. Patient satisfaction rate was analyzed using SPSS 20 software. The average of recovery rate was 54.7% using the combination method and 43.0% using laser alone ( P < 0.001). The mean patient satisfaction was significantly higher with the combination method than laser alone (6.6 ± 1.2 vs. 5.2 ± 1.8; P < 0.001). Bruising was only seen with the combination method and lasted for 1 week in 57.0% and for 2 weeks in 43.0%. Erythema was seen in both methods. Postinflammatory pigmentation and hyperpigmentation were associated with combination method. No persistent side effects were seen after 6 months. Using a combination of subcision and laser had suitable results regarding scar recovery and satisfaction rate.

Skin graft take and healing following 193-nm excimer, continuous-wave carbon dioxide (CO2), pulsed CO2, or pulsed holmium: YAG laser ablation of the graft bed.

PubMed

Green, H A; Burd, E E; Nishioka, N S; Compton, C C

1993-08-01

Ablative lasers have been used for cutaneous surgery for greater than two decades since they can remove skin and skin lesions bloodlessly and efficiently. Because full-thickness skin wounds created after thermal laser ablation may require skin grafting in order to heal, we have examined the effect of the residual laser-induced thermal damage in the wound bed on subsequent skin graft take and healing. In a pig model, four different pulsed and continuous-wave lasers with varying wavelengths and radiant energy exposures were used to create uniform fascial graft bed thermal damage of approximately 25, 160, 470, and 1100 microns. Meshed split-thickness skin graft take and healing on the thermally damaged fascial graft beds were examined on a gross and microscopic level on days 3 and 7, and then weekly up to 42 days. Laser-induced thermal damage on the graft bed measuring greater than 160 +/- 60 microns in depth significantly decreased skin graft take. Other deleterious effects included delayed graft revascularization, increased inflammatory cell infiltrate at the graft-wound bed interface, and accelerated formation of hypertrophied fibrous tissue within the graft bed and underlying muscle. Ablative lasers developed for cutaneous surgery should create less than 160 +/- 60 microns of residual thermal damage to permit optimal skin graft take and healing. Pulsed carbon dioxide and 193-nm excimer lasers may be valuable instruments for the removal of full-thickness skin, skin lesions, and necrotic tissue, since they create wound beds with minimal thermal damage permitting graft take comparable to that achieved with standard surgical techniques.

Dentin ablation-rate measurements in endodontics witj HF and CO2 laser radiation

NASA Astrophysics Data System (ADS)

Makropoulou, Mersini I.; Serafetinides, Alexander A.; Khabbaz, Marouan; Sykaras, Sotirios; Tsikrikas, G. N.

1996-01-01

Recent studies focused on the ability of the laser light to enlarge the root canal during the endodontic therapy. The aim of this research is the experimental and theoretical study of the ablation rate of two infrared laser wavelengths on dentin. Thirty freshly extracted human teeth were longitudinally sectioned at thicknesses ranged from 0.5 to 2 mm, and irradiated on the root canal dentin. The measured ablation rates in dentinal wall of the root canal showed that the HF laser at 2.9 micrometer can more effectively penetrate into the tissue, whereas the carbon dioxide laser at 10.6 micrometer leads to high thermal damage of the ablation crater surroundings.

Closed Cycle Electric Discharge Laser Design Investigation

DTIC Science & Technology

1978-03-01

Report Number Assigned by Contract Monitor: NASA CR- 135408 Comments on Document: Archive, RRI, DEW Descriptors, Keywords: Closed Cycle Electric...Discharge Laser Design Investigation Carbon Dioxide Monoxide Space Airborne Heat Disposal Point Track Power Solar Generator Radiation Pages: 00100...Cataloged Date: Nov 27,1992 Contract Number: NAS 3-20100 Document Type: HC Number of Copies In Library: 000001 Record ID: 25219 Source of Document: DEW

Safety management of an underground-based gravitational wave telescope: KAGRA

NASA Astrophysics Data System (ADS)

Ohishi, Naoko; Miyoki, Shinji; Uchiyama, Takashi; Miyakawa, Osamu; Ohashi, Masatake

2014-08-01

KAGRA is a unique gravitational wave telescope with its location underground and use of cryogenic mirrors. Safety management plays an important role for secure development and operation of such a unique and large facility. Based on relevant law in Japan, Labor Standard Act and Industrial Safety and Health Law, various countermeasures are mandated to avoid foreseeable accidents and diseases. In addition to the usual safety management of hazardous materials, such as cranes, organic solvents, lasers, there are specific safety issues in the tunnel. Prevention of collapse, flood, and fire accidents are the most critical issues for the underground facility. Ventilation is also important for prevention of air pollution by carbon monoxide, carbon dioxide, organic solvents and radon. Oxygen deficiency should also be prevented.

40 CFR 60.1230 - What continuous emission monitoring systems must I install for gaseous pollutants?

Code of Federal Regulations, 2010 CFR

2010-07-01

... systems for oxygen (or carbon dioxide), sulfur dioxide, and carbon monoxide. If you operate a Class I... sulfur dioxide, nitrogen oxides, and oxygen (or carbon dioxide) at the outlet of the air pollution... according to the “Monitoring Requirements” in § 60.13. (c) You must monitor the oxygen (or carbon dioxide...

40 CFR 60.1230 - What continuous emission monitoring systems must I install for gaseous pollutants?

Code of Federal Regulations, 2011 CFR

2011-07-01

... systems for oxygen (or carbon dioxide), sulfur dioxide, and carbon monoxide. If you operate a Class I... sulfur dioxide, nitrogen oxides, and oxygen (or carbon dioxide) at the outlet of the air pollution... according to the “Monitoring Requirements” in § 60.13. (c) You must monitor the oxygen (or carbon dioxide...

Laser-assisted electron tunneling in a STM junction

NASA Astrophysics Data System (ADS)

Chang, Shunhua Thomas

2000-10-01

Since its introduction in 1981, the Nobel prize-winning scanning tunneling microscope (STM) has been developed into a powerful yet conceptually simple instrument, replacing traditional scanning and transmission electron microscopes (SEM/TEM) in many of the microscopic surface phenomenon studies. The strength of the STM stems from the sensitive tunneling current-potential barrier width relationship of the electron tunneling process, and has been used to re-examine the frequency-mixing and harmonic generation properties of an non-linear metal- oxide-metal (MOM) tunneling junction. In this research, electron-tunneling events under polarized laser radiation at 514.5-nm argon and 10.6-μm carbon dioxide laser wavelengths were investigated. The objective is to understand the underlying interactive mechanisms between the tunneling junction and the external laser excitation. A commercial scanning tunneling microscope head and controller were incorporated into the experimental setup. Operation characteristics and the electrical properties of the STM junction were determined. Tunneling current and distance responses with respect to different laser polarization, modulation frequency, incident power, and tunneling distance were also conducted. From the experimental results it is shown that thermal expansion effect was the dominant source of response for laser modulation frequency up to about 100 kHz, in quantitative agreement with theoretical calculations. Different laser polarizations as the experiments demonstrated did not contribute significantly to the STM response in the investigated frequency range. The electric field induced by the laser beam was calculated to be one to two order of magnitudes lower than the field required to initiate field emission where the tunneling junction I- V curve is most non-linear. Also, the electrical coupling of the incident laser at the STM junction was determined to be non-critical at visible laser wavelength, and the reflected laser energy from the sample re-entering the junction was shown to be weak and did not influence the ongoing electron tunneling process. In conclusion, the thermal expansion of the physical tunneling junction was found to be responsible to the tunneling current modulation in a laser - STM setup for laser modulation frequencies in the lower frequency range.

Spectral-kinetic characteristics of luminescence of pentaerythritol tetranitrate with inclusions of iron nanoparticles upon explosion induced by laser pulses

NASA Astrophysics Data System (ADS)

Aduev, B. P.; Nurmukhametov, D. R.; Belokurov, G. M.; Nelyubina, N. V.; Gudilin, A. V.

2017-03-01

Spectral-kinetic characteristics of luminescence of tetranitropentaeritrite with inclusions of iron nanoparticles upon an explosion induced by laser pulses are measured with high temporal resolution. It is shown that the luminescence occurring during exposure to the laser pulse is a result of initiating a chemical reaction in tetranitropentaeritrite and is chemiluminescence. The glow is presumably associated with the excited nitrogen dioxide, NO2, which is formed by the rupture of O-NO2 bond in the tetranitropentaeritrite molecule.

NO2 heterodyne frequency measurements with a tunable diode laser, a CO laser transfer oscillator and CO2 laser standards

NASA Technical Reports Server (NTRS)

Zink, L. R.; Vanek, M.; Wells, J. S.

1987-01-01

Heterodyne frequency measurements have been made on selected groups of nitrogen dioxide rovibronic transitions between 1580.8 and 1650.7/cm. The groups are separated by 7 to 10/cm, and the intent is to provide a limited (and interim) calibration table for the region. In addition to a table of measured frequencies in the region, figures of spectra in the vicinity of the measured lines are included to provide a map for identifying the transitions measured.

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Study of photoinduced absorption by the method of modified laser photothermal radiometry

NASA Astrophysics Data System (ADS)

Skvortsov, L. A.; Maksimov, E. M.; Tuchkov, A. A.

2008-10-01

The application of the method of modified laser photothermal radiometry for studying the photoinduced absorption in thin films is considered. The sensitivity of the method is estimated. The mechanism of induced near-IR absorption in titanium dioxide films is proposed and the nature of surface defects responsible for this process is explained. It is shown that kinetic equations describing monomolecular recombination are consistent with the experimental dependences for the thermal activation energy of defects equal to 0.17±0.04 eV.

Laser welding of polypropylene using two different sources

NASA Astrophysics Data System (ADS)

Mandolfino, Chiara; Brabazon, Dermot; McCarthy, Éanna; Lertora, Enrico; Gambaro, Carla; Ahad, Inam Ul

2017-10-01

In this paper, laser weldability of neutral polypropylene has been investigated using fibre and carbon dioxide lasers. A design of experiment (DoE) was conducted in order to establish the influence of the main working parameters on the welding strength of the two types of laser. The welded samples were characterized by carrying out visual and microscopic inspection for the welding morphology and cross-section, and by distinguishing the tensile strength. The resulting weld quality was investigated by means of optical microscopy at weld cross-sections. The tensile strength of butt-welded materials was measured and compared to that of a corresponding bulk material.

Suppression of suprathermal ions from a colloidal microjet target containing SnO2 nanoparticles by using double laser pulses

NASA Astrophysics Data System (ADS)

Higashiguchi, Takeshi; Kaku, Masanori; Katto, Masahito; Kubodera, Shoichi

2007-10-01

We have demonstrated suppression of suprathermal ions from a colloidal microjet target plasma containing tin-dioxide (SnO2) nanoparticles irradiated by double laser pulses. We observed a significant decrease of the tin and oxygen ion signals in the charged-state-separated energy spectra when double laser pulses were irradiated. The peak energy of the singly ionized tin ions decreased from 9to3keV when a preplasma was produced. The decrease in the ion energy, considered as debris suppression, is attributed to the interaction between an expanding low-density preplasma and a main laser pulse.

Refurbishment of one-person regenerative air revitalization system

NASA Technical Reports Server (NTRS)

Powell, Ferolyn T.

1989-01-01

Regenerative processes for the revitalization of spacecraft atmospheres and reclamation of waste waters are essential for making long-term manned space missions a reality. Processes studied include: static feed water electrolysis for oxygen generation, Bosch carbon dioxide reduction, electrochemical carbon dioxide concentration, vapor compression distillation water recovery, and iodine monitoring. The objectives were to: provide engineering support to Marshall Space Flight Center personnel throughout all phases of the test program, e.g., planning through data analysis; fabricate, test, and deliver to Marshall Space Flight Center an electrochemical carbon dioxide module and test stand; fabricate and deliver an iodine monitor; evaluate the electrochemical carbon dioxide concentrator subsystem configuration and its ability to ensure safe utilization of hydrogen gas; evaluate techniques for recovering oxygen from a product oxygen and carbon dioxide stream; and evaluate the performance of an electrochemical carbon dioxide concentrator module to operate without hydrogen as a method of safe haven operation. Each of the tasks were related in that all focused on providing a better understanding of the function, operation, and performance of developmental pieces of environmental control and life support system hardware.

Portable Unit for Metabolic Analysis

NASA Technical Reports Server (NTRS)

Dietrich, Daniel L.; Pitch, Nancy D.; Lewis, Mark E.; Juergens, Jeffrey R.; Lichter, Michael J.; Stuk, Peter M.; Diedrick, Dale M.; Valentine, Russell W.; Pettegrew, Richard D.

2007-01-01

The Portable Unit for Metabolic Analysis (PUMA) is an instrument that measures several quantities indicative of human metabolic function. Specifically, this instrument makes time-resolved measurements of temperature, pressure, flow, and the partial pressures of oxygen and carbon dioxide in breath during both inhalation and exhalation. Portable instruments for measuring these quantities have been commercially available, but the response times of those instruments are too long to enable temporal resolution of phenomena on the time scales of human respiration cycles. In contrast, the response time of the PUMA is significantly shorter than characteristic times of human respiration phenomena, making it possible to analyze varying metabolic parameters, not only on sequential breath cycles but also at successive phases of inhalation and exhalation within the same breath cycle. In operation, the PUMA is positioned to sample breath near the subject s mouth. Commercial off-the-shelf sensors are used for three of the measurements: a miniature pressure transducer for pressure, a thermistor for temperature, and an ultrasonic sensor for flow. Sensors developed at Glenn Research Center are used for measuring the partial pressures of oxygen and carbon dioxide: The carbon dioxide sensor exploits the relatively strong absorption of infrared light by carbon dioxide. Light from an infrared source passes through the stream of inhaled or exhaled gas and is focused on an infrared- sensitive photodetector. The oxygen sensor exploits the effect of oxygen in quenching the fluorescence of ruthenium-doped organic molecules in a dye on the tip of an optical fiber. A blue laser diode is used to excite the fluorescence, and the optical fiber carries the fluorescent light to a photodiode, the temporal variation of the output of which bears a known relationship with the rate of quenching of fluorescence and, hence, with the partial pressure of oxygen. The outputs of the sensors are digitized, preprocessed by a small onboard computer, and then sent wirelessly to a desktop computer, where the collected data are analyzed and displayed. In addition to the raw data on temperature, pressure, flow, and mole fractions of oxygen and carbon dioxide, the display can include volumetric oxygen consumption, volumetric carbon dioxide production, respiratory equivalent ratio, and volumetric flow rate of exhaled gas.

A Laser-Induced Fluorescence Instrument for Aircraft Measurements of Sulfur Dioxide in the Upper Troposphere and Lower Stratosphere

NASA Technical Reports Server (NTRS)

Rollins, Andrew W.; Thornberry, Troy D.; Ciciora, Steven J.; McLaughlin, Richard J.; Watts, Laurel A.; Hanisco, Thomas F.; Baumann, Esther; Giorgetta, Fabrizio R.; Bui, Thaopaul V.; Fahey, David W.

2016-01-01

This work describes the development and testing of a new instrument for in situ measurements of sulfur dioxide (SO2) on airborne platforms in the upper troposphere and lower stratosphere (UTLS). The instrument is based on the laser-induced fluorescence technique and uses the fifth harmonic of a tunable fiber-amplified semiconductor diode laser system at 1084.5 nm to excite SO2 at 216.9 nm. Sensitivity and background checks are achieved in flight by additions of SO2 calibration gas and zero air, respectively. Aircraft demonstration was performed during the NASA Volcano Plume Investigation Readiness and Gas-Phase and Aerosol Sulfur (VIRGAS) experiment, which was a series of flights using the NASA WB-57F during October 2015 based at Ellington Field and Harlingen, Texas. During these flights, the instrument successfully measured SO2 in the UTLS at background (non-volcanic) conditions with a precision of 2 ppt at 10 s and an overall uncertainty determined primarily by instrument drifts of +/- (16% + 0.9 ppt).

Fiber Lasers and Amplifiers for Space-based Science and Exploration

NASA Technical Reports Server (NTRS)

Yu, Anthony W.; Krainak, Michael A.; Stephen, Mark A.; Chen, Jeffrey R.; Coyle, Barry; Numata, Kenji; Camp, Jordan; Abshire, James B.; Allan, Graham R.; Li, Steven X.;

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.

Integrated Testing of a Carbon Dioxide Removal Assembly and a Temperature-Swing Adsorption Compressor for Closed-Loop Air Revitalization

NASA Technical Reports Server (NTRS)

Knox, J. C.; Mulloth, Lila; Frederick, Kenneth; Affleck, Dave

2003-01-01

Accumulation and subsequent compression of carbon dioxide that is removed from space cabin are two important processes involved in a closed-loop air revitalization scheme of the International Space Station (ISS). The carbon dioxide removal assembly (CDRA) of ISS currently operates in an open loop mode without a compressor. This paper describes the integrated test results of a flight-like CDRA and a temperature-swing adsorption compressor (TSAC) for carbon dioxide removal and compression. The paper provides details of the TSAC operation at various CO2 loadings and corresponding performance of CDRA.

Evaluation of Carbon Dioxide Laser in the Treatment of Epidermal Nevi

PubMed Central

Bhat, Yasmeen Jabeen; Hassan, Iffat; Sajad, Peerzada; Yaseen, Atiya; Mubashir, Syed; Akhter, Saniya; Wani, Roohi

2016-01-01

Background: Epidermal naevi are benign hamartomatous growths of the skin which are generally asymptomatic with a benign course but are cosmetically disagreeable. Topical treatments such as steroids, calcipotriol, 5 fluorouracil, podophyllin, retinoids and cryotherapy are ineffective and surgical excision results in scar formation. Therapy is often challenging. Aim of the Study: To study the response of carbon dioxide (CO2) laser in the management of epidermal naevi. Subjects and Methods: We conducted a study of CO2 laser treatment on 15 patients of epidermal naevi, eight with verrucous epidermal naevi and seven with sebaceous naevi. A thorough history and examination was done to rule out any epidermal naevus syndrome. The diagnosis was confirmed by histopathology. The number of treatment sessions varied from 1 to 8. Results: Response was excellent (>90% reduction in lesion size) in three patients, very good (>75% reduction) in five, good (>50% reduction in lesion size) in five and poor (<50% reduction in lesion size) in two patients. The side effects were hyperpigmentation and scarring. Long-term follow-up over a period of 10 months showed a recurrence rate of 20%. Conclusion: We conclude that CO2 laser treatment might be an effective option with long-term safety, minimal discomfort and rapid recovery. PMID:27761089

Molecular systems under shock compression into the dense plasma regime: carbon dioxide and hydrocarbon polymers

NASA Astrophysics Data System (ADS)

Mattsson, Thomas R.; Cochrane, Kyle R.; Root, Seth; Carpenter, John H.

2013-10-01

Density Functional Theory (DFT) has proven remarkably accurate in predicting properties of matter under shock compression into the dense plasma regime. Materials where chemistry plays a role are of interest for many applications, including planetary science and inertial confinement fusion (ICF). As examples of systems where chemical reactions are important, and demonstration of the high fidelity possible for these both structurally and chemically complex systems, we will discuss shock- and re-shock of liquid carbon dioxide (CO2) in the range 100 to 800 GPa and shock compression of hydrocarbon polymers, including GDP (glow discharge polymer) which is used as an ablator in laser ICF experiments. Experimental results from Sandia's Z machine validate the DFT simulations at extreme conditions and the combination of experiment and DFT provide reliable data for evaluating existing and constructing future wide-range equations of state models for molecular compounds. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Pseudorandom Noise Code-Based Technique for Thin Cloud Discrimination with CO2 and O2 Absorption Measurements

NASA Technical Reports Server (NTRS)

Campbell, Joel F.; Prasad, Narasimha S.; Flood, Michael A.

2011-01-01

NASA Langley Research Center is working on a continuous wave (CW) laser based remote sensing scheme for the detection of CO2 and O2 from space based platforms suitable for ACTIVE SENSING OF CO2 EMISSIONS OVER NIGHTS, DAYS, AND SEASONS (ASCENDS) mission. ASCENDS is a future space-based mission to determine the global distribution of sources and sinks of atmospheric carbon dioxide (CO2). A unique, multi-frequency, intensity modulated CW (IMCW) laser absorption spectrometer (LAS) operating at 1.57 micron for CO2 sensing has been developed. Effective aerosol and cloud discrimination techniques are being investigated in order to determine concentration values with accuracies less than 0.3%. In this paper, we discuss the demonstration of a pseudo noise (PN) code based technique for cloud and aerosol discrimination applications. The possibility of using maximum length (ML)-sequences for range and absorption measurements is investigated. A simple model for accomplishing this objective is formulated, Proof-of-concept experiments carried out using SONAR based LIDAR simulator that was built using simple audio hardware provided promising results for extension into optical wavelengths.

Towards a Precision Measurement of the Lamb Shift in Hydrogen-Like Nitrogen

NASA Astrophysics Data System (ADS)

Myers, E. G.; Tarbutt, M. R.

Measurements of the 2S1/2-2P1/2 and 2S1/2 -2P3/2 transitions in moderate Z hydrogen-like ions can test Quantum-Electrodynamic calculations relevant to the interpretation of high-precision spectroscopy of atomic hydrogen. There is now particular interest in testing calculations of the two-loop self-energy. Experimental conditions are favorable for a measurement of the 2S1/2 - 2P3/2 transition in N6+ using a carbon dioxide laser. As a preliminary experiment, we have observed the 2S1/2 -2P3/2 transition in 14N6+ using a 2.5 MeV2 laser operating on the hot band of 12C16O2. The measured value of the transition centroid, 834.94(7) cm-1, agrees with, but is less precise than theory. However, the counting rate and signal-to-background ratio obtained indicate, that with careful control of systematics, a precision test of the theory is practical. Work towards constructing such a set-up is in pro gress.

Remote measurements of ozone, water vapor and liquid water content, and vertical profiles of temperature in the lower troposphere

NASA Technical Reports Server (NTRS)

Grant, W. B.; Gary, B. L.; Shumate, M. S.

1983-01-01

Several advanced atmospheric remote sensing systems developed at the Jet Propulsion Laboratory were demonstrated under various field conditions to determine how useful they would be for general use by the California Air Resources Board and local air quality districts. One of the instruments reported on is the Laser Absorption Spectrometer (LAS). It has a pair of carbon dioxide lasers with a transmitter and receiver and can be flown in an aircraft to measure the column abundance of such gases as ozone. From an aircraft, it can be used to rapidly survey a large region. The LAS is usually operated from an aircraft, although it can also be used at a fixed location on the ground. Some tests were performed with the LAS to measure ozone over a 2-km horizontal path. Another system reported on is the Microwave Atmospheric Remote Sensing System (MARS). It is tuned to microwave emissions from water vapor, liquid water, and oxygen molecules (for atmospheric temperature). It can measure water vapor and liquid water in the line-of-sight, and can measure the vertical temperature profile.

Carbon dioxide laser ablation of dermatosis papulosa nigra: high satisfaction and few complications in patients with pigmented skin.

PubMed

Ali, Faisal R; Bakkour, Waseem; Ferguson, Janice E; Madan, Vishal

2016-04-01

Dermatosis papulosa nigra (DPN) is a common condition of pigmented skin. Whilst lesions are benign, they may be symptomatic or cosmetically disfiguring. Ablative lasers have previously been reported as a useful therapeutic modality in DPN. We report the largest case series to date of patients with DPN ablated with the carbon dioxide (CO2) laser. A retrospective case note review was conducted of all patients with DPN treated in our laser clinic in the last five years, and a post-treatment telephone survey was undertaken to assess patient satisfaction. Forty-five patients were identified, with a median age of 41 years (range 25-74 years), of whom 37 (82%) were female. The median number of treatments undertaken was three (range 1-10). Of the 18 respondents to the telephone survey, when asked to grade their satisfaction with the procedure out of 10, median response was 9.5 (range 6-10) with nine patients citing the maximum score of 10. All patients replied that their confidence had improved following the procedure and that they would recommend the treatment to other patients. Five respondents (28%) reported recurrence of a few lesions following CO2 laser ablation; the remaining 13 respondents (72%) reported no recurrence of DPN. No respondents reported any other post-procedural complications (including scarring, hypopigmentation and hyperpigmentation). We advocate use of the CO2 laser as a safe, convenient means of treating DPN, with a high degree of patient satisfaction, low recurrence rate and few complications.

Plasmonic enhancement of the vanadium dioxide phase transition induced by low-power laser irradiation

NASA Astrophysics Data System (ADS)

Ferrara, Davon W.; MacQuarrie, Evan R.; Diez-Blanco, Victor; Nag, Joyeeta; Kaye, Anthony B.; Haglund, Richard F.

2012-08-01

Nanocomposites consisting of gold nanoparticle (NP) arrays and vanadium dioxide (VO2) thin films are noteworthy for the tunability of both their thermal and optical properties. The localized surface plasmon resonance (LSPR) of the Au can be tuned when its dielectric environment is modulated by the semiconducting-to-metal phase transition (SMT) of the VO2; the LSPR itself can be altered by changing the shape of the NPs and the pitch of the NP array. In principle, then it should be possible to choose a combination of VO2 film and Au LSPR properties that maximizes the overall optical response of the nanocomposite. To demonstrate this effect, transient transmission measurements were conducted on lithographically fabricated arrays of Au NPs of diameter 140 nm, array spacing 350 nm, and covered with a 60 nm thick films of VO2 via pulsed laser deposition. Both Au::VO2 nanocomposites and bare VO2 film were irradiated with a shuttered 785 nm pump laser, and their optical response was probed at 1550 nm by a fixed-frequency diode laser. The Au::VO2 nanocomposite exhibited an increased effective absorption coefficient 1.5 times that of the plain film and required 37 % less laser power to induce the SMT. The time-dependent temperature rise in the film as a function of laser intensity was calculated from these measurements and compared with both analytic and finite-element models. Our results suggest that Au::VO2 nanocomposites may be useful in applications such as thermal-management coatings for energy efficient "smart" windows.

Overview of International Space Station Carbon Dioxide Removal Assembly On-Orbit Operations and Performance

NASA Technical Reports Server (NTRS)

Matty, Christopher M.

2013-01-01

Controlling Carbon Dioxide (CO2) partial pressure in the habitable vehicle environment is a critical part of operations on the International Space Station (ISS). On the United States segment of ISS, CO2 levels are primarily controlled by the Carbon Dioxide Removal Assembly (CDRA). There are two CDRAs on ISS; one in the United States Laboratory module, and one in the Node3 module. CDRA has been through several significant operational issues, performance issues and subsequent re-design of various components, primarily involving the Desiccant Adsorbent Bed (DAB) assembly and Air Selector Valves (ASV). This paper will focus on significant operational and performance issues experienced by the CDRA team from 2008-2012.

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.

Nitrogen dioxide exposures inside ice skating rinks.

PubMed Central

Brauer, M; Spengler, J D

1994-01-01

OBJECTIVES. The common operation of fuel-powered resurfacing equipment in enclosed ice skating rinks has the potential for producing high concentrations of carbon monoxide and nitrogen dioxide. Exposures to these gaseous combustion products may adversely affect the health of those inside the rink. Little information is available on pollutant concentrations under normal operating conditions. METHODS. One-week average nitrogen dioxide concentrations in 70 northeastern US rinks were measured with passive samplers during normal winter season conditions. RESULTS. The median nitrogen dioxide level inside rinks was 180 ppb, more than 10 times higher than the median outdoor concentration. One-week average nitrogen dioxide concentrations above 1000 ppb were measured in 10% of the rinks. CONCLUSIONS. Considering that short-term peak concentrations were likely to have reached two to five times the measured 1-week averages, our results suggest that nitrogen dioxide levels were well above short-term air quality guidelines and constitute a public health concern of considerable magnitude. PMID:8129060

Joint EPA/NASA/USAF Interagency Depainting Study

NASA Technical Reports Server (NTRS)

Clark-Ingram, M.

2001-01-01

Environmental regulations such as National Emission Standards for Hazardous Air Pollutants (NESHAPs) are drivers for the implementation of environmentally compliant methodologies in the manufacture of aerospace hardware. In 1995, the Environmental Protection Agency (EPA) promulgated the NESHAP for the Aerospace Manufacture and Rework (Aerospace NESHAP) industry. Affected facilities were to be in compliance by September 1998. Several aerospace manufacturing operations are regulated within the Aerospace NESHAP including Depainting operations. The National Aeronautics and Space Administration (NASA), EPA, and United States Air Force (USAF) combined resources to evaluate the performance of nine alternative depainting processes. The seven alternative depainting processes were: (1) Chemical stripping (non-methylene chloride); (2) Carbon Dioxide Blasting; (3) Xenon Flashlamp; (4) Carbon Dioxide Laser Stripping; (5) Plastic Media Blasting; (6) Sodium Bicarbonate Wet Stripping; and (7) Waterjet Blasting and Wheat Starch Blasting. All epoxy primer and polyurethane top coat system was applied to 2024-T3 clad and non-clad aluminum test specimens. Approximately 200 test specimens were evaluated in this study. Each coupon was subjected to three, four, or five complete depainting cycles. This paper discusses the conclusions from the study including the test protocol, test parameters, and achievable strip rates for the alternative depainting processes. Test data includes immersion corrosion testing, sandwich corrosion testing and hydrogen embrittlement testing for the non-methylene chloride chemical strippers. Additionally, the cumulative effect of the alternative depainting processes on the metallurgical integrity of the test substrate is addressed with the results from tensile and fatigue evaluations.

Quantitative comparison of inflammatory infiltrate and linear contraction in human skin treated with 90-microsecond pulsed and 900-microsecond dwell time carbon dioxide lasers.

PubMed

Bucalo, B D; Moy, R L

1998-12-01

Skin resurfacing with 90-microsecond pulse duration carbon dioxide (CO2) resurfacing lasers has been reported to have shorter duration of erythema compared with skin resurfacing with 900-microsecond dwell time lasers. The presence of inflammatory infiltrate following resurfacing may correlate with the persistence of this erythema. Furthermore, skin treated with the 90-microsecond pulse duration laser and the 900-microsecond dwell time lasers both result in equivalent improvement of rhytids in the treated skin. To quantitative the inflammatory cell infiltrate and linear contraction of skin treated with the 90-microsecond pulsed and 900-microsecond dwell time CO2 lasers at intervals of 2 and 4 weeks after treatment. Volunteers were recruited from patients who were planning to undergo full face laser resurfacing under general anesthesia. Informed consent was obtained from all volunteers. In the posterior auricular areas of all volunteers, four separate rectangular areas were marked using a skin marking pen and a template. Two rectangular areas behind the right ear were treated with 6 passes of the 90-microsecond laser and two rectangular areas behind the left ear were treated with the 900-microsecond dwell time laser. The resurfaced areas were wiped with a moist cotton swab and then patted dry with dry gauze between passes. Contraction measurements of the resurfaced areas were taken before and immediately after laser treatment and again at 2 and 4 weeks following treatment. Punch biopsies were also performed at 2 and 4 weeks after treatment in an area of skin different from where contraction measurements were taken. The number of inflammatory cells present in the skin at 2 and 4 weeks after laser resurfacing are greater for skin resurfaced with a 900-microsecond dwell time laser than a 90-microsecond pulse time laser. Linear contraction of skin immediately after treatment was 18% greater with the 900-microsecond dwell time laser than with the 90-microsecond pulsed laser. The difference in the amount of contraction produced by the lasers tended to decrease over time. At 4 weeks there was a 10% difference in mean linear contraction between the two laser types. Increased numbers of inflammatory cells in skin resurfaced with the 900-microsecond dwell time laser may explain the observed persistence of erythema associated with the 900-microsecond dwell time laser. Measurable linear contraction produced by the 900-microsecond dwell time laser was initially 18% greater than the 90-microsecond pulse laser. This difference tends to decrease over time.

Comparative evaluation of the three different surface treatments - conventional, laser and Nano technology methods in enhancing the surface characteristics of commercially pure titanium discs and their effects on cell adhesion: An in vitro study.

PubMed

Vignesh; Nayar, Sanjna; Bhuminathan; Mahadevan; Santhosh, S

2015-04-01

The surface area of the titanium dental implant materials can be increased by surface treatments without altering their shape and form, thereby increasing the biologic properties of the biomaterial. A good biomaterial helps in early cell adhesion and cell signaling. In this study, the commercially pure titanium surfaces were prepared to enable machined surfaces to form a control material and to be compared with sandblasted and acid-etched surfaces, laser treated surfaces and titanium dioxide (20 nm) Nano-particle coated surfaces. The surface elements were characterized. The biocompatibility was evaluated by cell culture in vitro using L929 fibroblasts. The results suggested that the titanium dioxide Nano-particle coated surfaces had good osteoconductivity and can be used as a potential method for coating the biomaterial.

Photoacoustic measurement of ammonia in the atmosphere: influence of water vapor and carbon dioxide

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

Rooth, R.A.; Verhage, A.J.L.; Wouters, L.W.

1990-09-01

The photoacoustic determination of the ammonia concentration in atmospheric air by absorption of CO{sub 2} laser radiation at 9.22 {mu}m is influenced by the presence of H{sub 2}O and CO{sub 2}. Kinetic cooling due to the coupling of excited CO{sub 2} and N{sub 2} levels causes important changes in phase and amplitude of the photoacoustic signal. Theoretical background is presented to deduce the correct NH{sub 3} concentration from the signal. The experimental setup used to perform field measurements is described. Adhesion of NH{sub 3} to the walls of the resonant photoacoustic cell was investigated. Temperature effects are treated. Field datamore » of NH{sub 3} and H{sub 2}O concentrations are presented. Key words: Photoacoustics, ammonia, kinetic cooling, trace gas measurements, ammonia adhesion, acoustic resonance, CO{sub 2} laser radiation, water vapor absorption, carbon dioxide absorption.« less

The detection of carbon dioxide leaks using quasi-tomographic laser absorption spectroscopy measurements in variable wind

DOE PAGES

Levine, Zachary H.; Pintar, Adam L.; Dobler, Jeremy T.; ...

2016-04-13

Laser absorption spectroscopy (LAS) has been used over the last several decades for the measurement of trace gasses in the atmosphere. For over a decade, LAS measurements from multiple sources and tens of retroreflectors have been combined with sparse-sample tomography methods to estimate the 2-D distribution of trace gas concentrations and underlying fluxes from point-like sources. In this work, we consider the ability of such a system to detect and estimate the position and rate of a single point leak which may arise as a failure mode for carbon dioxide storage. The leak is assumed to be at a constant ratemore » giving rise to a plume with a concentration and distribution that depend on the wind velocity. Lastly, we demonstrate the ability of our approach to detect a leak using numerical simulation and also present a preliminary measurement.« less

Real Time Diagnostics of Jet Engine Exhaust Plumes Using a Chirped QC Laser Spectrometer

NASA Astrophysics Data System (ADS)

Hay, K. G.; Duxbury, G.; Langford, N.

2010-06-01

Quantitative measurements of real-time variations of the chemical composition of a jet engine exhaust plume is demonstrated using a 4.86 μmn intra-pulse quantum cascade laser spectrometer. The measurements of the gas turbine exhaust were carried out in collaboration with John Black and Mark Johnson at Rolls Royce. The recording of five sets of averaged spectra a second has allowed us to follow the build up of the combustion products within the exhaust, and to demonstrate the large variation of the integrated absorption of these absorption lines with temperature. The absorption cross sections of the lines of both carbon monoxide and water increase with temperature, whereas those of the three main absorption lines of carbon dioxide decrease. At the steady state limit the absorption lines of carbon dioxide are barely visible, and the spectrum is dominated by absorption lines of carbon monoxide and water.

International Space Station Carbon Dioxide Removal Assembly Testing

NASA Technical Reports Server (NTRS)

Knox, James C.

2000-01-01

Performance testing of the International Space Station Carbon Dioxide Removal Assembly flight hardware in the United States Laboratory during 1999 is described. The CDRA exceeded carbon dioxide performance specifications and operated flawlessly. Data from this test is presented.

Optimized LWIR enhancement of nanosecond and femtosecond LIBS uranium emission

NASA Astrophysics Data System (ADS)

Akpovo, Codjo A.; Ford, Alan; Johnson, Lewis

2016-05-01

A carbon dioxide (CO2) transverse electrical breakdown in atmosphere (TEA), pulsed laser was used to enhance the laser-induced breakdown spectroscopy (LIBS) spectral signatures of uranium under nanosecond (ns) and femtosecond (fs) ablation. The peak areas of both ionic and neutral species increased by one order of magnitude for ns-ablation and two orders of magnitude for fs-ablation over LIBS when the CO2 TEA laser was used with samples of dried solutions of uranyl nitrate hexahydrate (UO2(NO3)2·6H2O) on silicon wafers. Electron temperature and density measurements show that the spectral emission improvement from using the TEA laser comes from plasma reheating.

Treatment of condylomata acuminata with CO2 laser under colposcopic control in pregnant women

NASA Astrophysics Data System (ADS)

Wozniak, Jakub; Opala, Tomasz; Pisarska-Krawczyk, Magdalena; Wilczak, Maciej; Pisarski, Tadeusz

1996-03-01

The results of treatment of condylomata acuminata of the anogenital region in pregnant women are presented. All patients were treated between the 28th and 35th weeks of gestation. The laser surgery was done in 23 patients. One laser procedure was done in 14 women. In 5 patients we performed two and in 4 women 3 laser therapies. Complete destruction of pathological changes was obtained and no recurrences were diagnosed. There were no clinical signs of HPV infection in all neonates. In the authors' opinion the use of carbon-dioxide laser under colposcopic control is an efficient and safe method in the treatment of condylomata acuminata in pregnant women. Colposcopic control allows us to discover and coagulate the bleeding spots using the defocused laser beam with low power density.

The use of lasers for periodontal debridement: marketing tool or proven therapy?

PubMed

Chanthaboury, Rachel; Irinakis, Tassos

2005-10-01

The use of lasers in dentistry has recently received much attention, in both clinical practice and research; their unique properties produce favourable clinical results in some cases and encourage patient acceptance. Various types of lasers have been investigated as an adjunct to periodontal therapy; these include carbon dioxide (CO₂), diode, neodymium:yttrium-aluminium-garnet (Nd:YAG) and erbium:yttrium-aluminium-garnet (Er:YAG) lasers.However, adverse results have been associated with each type, including thermal damage to root surfaces, increases in pulpal temperature and the production of toxic by-products. The Er:YAG laser has produced the most promising results, as it can ablate effectively with minimal adverse effects. More research is needed to determine the ideal settings and methods for using the laser safely and effectively in clinical practice.

46 CFR 35.40-7 - Carbon dioxide alarm-T/ALL.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 1 2011-10-01 2011-10-01 false Carbon dioxide alarm-T/ALL. 35.40-7 Section 35.40-7 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS Posting and Marking Requirements-TB/ALL. § 35.40-7 Carbon dioxide alarm—T/ALL. Adjacent to all carbon dioxide fire extinguishing...

46 CFR 97.37-9 - Carbon dioxide alarm.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 4 2011-10-01 2011-10-01 false Carbon dioxide alarm. 97.37-9 Section 97.37-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS OPERATIONS Markings for Fire and Emergency Equipment, Etc. § 97.37-9 Carbon dioxide alarm. (a) All carbon dioxide alarms shall be conspicuously identified: “WHEN...

46 CFR 78.47-9 - Carbon dioxide alarm.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 3 2011-10-01 2011-10-01 false Carbon dioxide alarm. 78.47-9 Section 78.47-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PASSENGER VESSELS OPERATIONS Markings for Fire and Emergency Equipment, Etc. § 78.47-9 Carbon dioxide alarm. (a) All carbon dioxide alarms shall be conspicuously identified: “WHEN ALARM...

46 CFR 131.815 - Carbon dioxide and clean agent alarms.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 4 2014-10-01 2014-10-01 false Carbon dioxide and clean agent alarms. 131.815 Section 131.815 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OFFSHORE SUPPLY VESSELS OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.815 Carbon dioxide and clean agent alarms. Each carbon dioxide or clean agent fire...

46 CFR 131.815 - Carbon dioxide and clean agent alarms.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 4 2012-10-01 2012-10-01 false Carbon dioxide and clean agent alarms. 131.815 Section 131.815 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OFFSHORE SUPPLY VESSELS OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.815 Carbon dioxide and clean agent alarms. Each carbon dioxide or clean agent fire...

46 CFR 131.815 - Carbon dioxide and clean agent alarms.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 4 2013-10-01 2013-10-01 false Carbon dioxide and clean agent alarms. 131.815 Section 131.815 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OFFSHORE SUPPLY VESSELS OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.815 Carbon dioxide and clean agent alarms. Each carbon dioxide or clean agent fire...

LPP-EUV light source for HVM lithography

NASA Astrophysics Data System (ADS)

Saito, T.; Ueno, Y.; Yabu, T.; Kurosawa, A.; Nagai, S.; Yanagida, T.; Hori, T.; Kawasuji, Y.; Abe, T.; Kodama, T.; Nakarai, H.; Yamazaki, T.; Mizoguchi, H.

2017-01-01

We have been developing a laser produced plasma extremely ultra violet (LPP-EUV) light source for a high volume manufacturing (HVM) semiconductor lithography. It has several unique technologies such as the high power short pulse carbon dioxide (CO2) laser, the short wavelength solid-state pre-pulse laser and the debris mitigation technology with the magnetic field. This paper presents the key technologies for a high power LPP-EUV light source. We also show the latest performance data which is 188W EUV power at intermediate focus (IF) point with 3.7% conversion efficiency (CE) at 100 kHz.

Antares alignment gimbal positioner

NASA Astrophysics Data System (ADS)

Day, R. D.; Viswanathan, V. K.; Saxman, A. C.; Lujan, R. E.; Woodfin, W. C.; Sweatt, W. C.

Antares is a 24-beam 40-TW carbon dioxide (CO2) laser fusion system currently under construction at the Los Alamos National Laboratory. The Antares alignment gimbal positioner (AGP) is an optomechanical instrument that will be used for target alignment and alignment of the 24 laser beams, as well as beam quality assessments. The AGP will be capable of providing pointing, focusing, an wavefront optical path difference, as well as aberration information at both helium neon (He-Ne) and CO2 wavelengths. It is designed to allow the laser beams to be aligned to any position within a 1 cm cube to a tolerance of 10 micrometers.

Three-dimensional ordered titanium dioxide-zirconium dioxide film-based microfluidic device for efficient on-chip phosphopeptide enrichment.

PubMed

Zhao, De; He, Zhongyuan; Wang, Gang; Wang, Hongzhi; Zhang, Qinghong; Li, Yaogang

2016-09-15

Microfluidic technology plays a significant role in separating biomolecules, because of its miniaturization, integration, and automation. Introducing micro/nanostructured functional materials can improve the properties of microfluidic devices, and extend their application. Inverse opal has a three-dimensional ordered net-like structure. It possesses a large surface area and exhibits good mass transport, making it a good candidate for bio-separation. This study exploits inverse opal titanium dioxide-zirconium dioxide films for on-chip phosphopeptide enrichment. Titanium dioxide-zirconium dioxide inverse opal film-based microfluidic devices were constructed from templates of 270-, 340-, and 370-nm-diameter poly(methylmethacrylate) spheres. The phosphopeptide enrichments of these devices were determined by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. The device constructed from the 270-nm-diameter sphere template exhibited good comprehensive phosphopeptide enrichment, and was the best among these three devices. Because the size of opal template used in construction was the smallest, the inverse opal film therefore had the smallest pore sizes and the largest surface area. Enrichment by this device was also better than those of similar devices based on nanoparticle films and single component films. The titanium dioxide-zirconium dioxide inverse opal film-based device provides a promising approach for the efficient separation of various biomolecules. Copyright © 2016 Elsevier Inc. All rights reserved.

40 CFR 90.320 - Carbon dioxide analyzer calibration.

Code of Federal Regulations, 2010 CFR

2010-07-01

... use and monthly thereafter, or within one month prior to the certification test, calibrate the NDIR... operation. Adjust the analyzer to optimize performance. (2) Zero the carbon dioxide analyzer with either purified synthetic air or zero-grade nitrogen. (3) Calibrate on each normally used operating range with...

46 CFR 35.40-10 - Steam, foam, carbon dioxide, or clean agent fire smothering apparatus-TB/ALL.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 1 2013-10-01 2013-10-01 false Steam, foam, carbon dioxide, or clean agent fire... TANK VESSELS OPERATIONS Posting and Marking Requirements-TB/ALL § 35.40-10 Steam, foam, carbon dioxide, or clean agent fire smothering apparatus—TB/ALL. Each steam, foam, carbon dioxide, or clean agent...

46 CFR 35.40-10 - Steam, foam, carbon dioxide, or clean agent fire smothering apparatus-TB/ALL.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 1 2014-10-01 2014-10-01 false Steam, foam, carbon dioxide, or clean agent fire... TANK VESSELS OPERATIONS Posting and Marking Requirements-TB/ALL § 35.40-10 Steam, foam, carbon dioxide, or clean agent fire smothering apparatus—TB/ALL. Each steam, foam, carbon dioxide, or clean agent...

46 CFR 97.37-9 - Carbon dioxide and clean agent alarms.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 4 2014-10-01 2014-10-01 false Carbon dioxide and clean agent alarms. 97.37-9 Section 97.37-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS OPERATIONS Markings for Fire and Emergency Equipment, Etc. § 97.37-9 Carbon dioxide and clean agent alarms. Each carbon dioxide or clean agent...

46 CFR 78.47-9 - Carbon dioxide and clean agent alarms.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 3 2013-10-01 2013-10-01 false Carbon dioxide and clean agent alarms. 78.47-9 Section 78.47-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PASSENGER VESSELS OPERATIONS Markings for Fire and Emergency Equipment, Etc. § 78.47-9 Carbon dioxide and clean agent alarms. Each carbon dioxide or clean agent fire...

46 CFR 78.47-9 - Carbon dioxide and clean agent alarms.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 3 2012-10-01 2012-10-01 false Carbon dioxide and clean agent alarms. 78.47-9 Section 78.47-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PASSENGER VESSELS OPERATIONS Markings for Fire and Emergency Equipment, Etc. § 78.47-9 Carbon dioxide and clean agent alarms. Each carbon dioxide or clean agent fire...

46 CFR 97.37-9 - Carbon dioxide and clean agent alarms.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 4 2013-10-01 2013-10-01 false Carbon dioxide and clean agent alarms. 97.37-9 Section 97.37-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS OPERATIONS Markings for Fire and Emergency Equipment, Etc. § 97.37-9 Carbon dioxide and clean agent alarms. Each carbon dioxide or clean agent...

46 CFR 97.37-9 - Carbon dioxide and clean agent alarms.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 4 2012-10-01 2012-10-01 false Carbon dioxide and clean agent alarms. 97.37-9 Section 97.37-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS OPERATIONS Markings for Fire and Emergency Equipment, Etc. § 97.37-9 Carbon dioxide and clean agent alarms. Each carbon dioxide or clean agent...

46 CFR 78.47-9 - Carbon dioxide and clean agent alarms.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 3 2014-10-01 2014-10-01 false Carbon dioxide and clean agent alarms. 78.47-9 Section 78.47-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PASSENGER VESSELS OPERATIONS Markings for Fire and Emergency Equipment, Etc. § 78.47-9 Carbon dioxide and clean agent alarms. Each carbon dioxide or clean agent fire...

Nonlinear-optical properties of thick composite media with vanadium dioxide nanoparticles. II. Self-focusing of mid-IR radiation

NASA Astrophysics Data System (ADS)

Vinogradova, O. P.; Ostrosablina, A. A.; Sidorov, A. I.

2006-02-01

This paper presents the experimental and theoretical results of a study of the interaction of pulsed laser radiation with thick composite media containing nanoparticles of vanadium dioxide (VO2). It is established that the reversible semiconductor-metal phase transition that occurs in the VO2 nanoparticles under the action of radiation can produce self-focusing of the mid-IR radiation by the formation of a photoinduced dynamic lens. An analysis is carried out of how the radiation intensity affects the dynamics of the given process.

Elasticity of α-Cristobalite: A Silicon Dioxide with a Negative Poisson's Ratio

NASA Astrophysics Data System (ADS)

Yeganeh-Haeri, Amir; Weidner, Donald J.; Parise, John B.

1992-07-01

Laser Brillouin spectroscopy was used to determine the adiabatic single-crystal elastic stiffness coefficients of silicon dioxide (SiO_2) in the α-cristobalite structure. This SiO_2 polymorph, unlike other silicas and silicates, exhibits a negative Poisson's ratio; α-cristobalite contracts laterally when compressed and expands laterally when stretched. Tensorial analysis of the elastic coefficients shows that Poisson's ratio reaches a maximum value of -0.5 in some directions, whereas averaged values for the single-phased aggregate yield a Poisson's ratio of -0.16.

Closed dressings after laser skin resurfacing.

PubMed

Newman, J P; Koch, R J; Goode, R L

1998-07-01

To evaluate the safety, efficacy, and patient acceptance of closed dressings after full facial resurfacing with the carbon dioxide laser. Prospective cohort of men and women undergoing full facial carbon dioxide laser resurfacing. Ambulatory surgical center at a university hospital. Forty consecutive patients randomized to 1 of 4 dressing groups. All patients underwent full facial resurfacing with a carbon dioxide laser system. One of 5 closed dressings (single- or 3-layer composite foam, plastic mesh, hydrogel, or polymer film) was placed immediately after the procedure. Closed dressings were changed on postoperative day 2 and removed on postoperative day 4. Objective postoperative criteria of erythema, scarring, reepithelialization, and surface irregularities were recorded and photodocumented. Comparisons were made among the closed dressing groups as well as with a group of historical control subjects treated with open dressings. The ease of application, office time for preparation and application, and cost of the individual dressings were collected. Patient characteristics of overall acceptance, comfort, and ease of maintenance were recorded with a visual analog scale. There were no complications of scarring, surface irregularities, or contact dermatitis from the application or maintenance of the closed dressings. There were no significant differences in the number of days of postoperative erythema or in the rate of facial reepithelialization among the groups. Most patients preferred not to continue with the closed dressings past 2 days. Positive features from the use of closed dressings included reduction in crust formation, decreased pruritus, decreased erythema, and decreased postoperative pain, compared with historical controls. Negative features included time in preparation and application of the dressings. Costs ranged from $9.79 to $50 per dressing change. Closed dressings are safe and offer benefits noted during the first 4 postoperative days. Patients can be expected to maintain a closed dressing for at least 24 hours but no longer than 4 days. The positive features of closed dressings and patient acceptance outweigh the cost and office time involved with their application and maintenance.

Laser Initiation of PETN containing Nickel Inclusions

NASA Astrophysics Data System (ADS)

Aduev, B. P.; Zvekov, A. A.; Nurmukhametov, D. R.; Nikitin, A. P.

2017-01-01

The spectral and kinetic characteristics of pentaerythritol tetranitrate (PETN) containing nickel nanoparticles glow initiated by laser pulses was studied with high temporal resolution. It was shown that glow which is chemiluminescence arises as a result of chemical reaction initiation. We suggest that the glow is concerned on excited nitrogen dioxide NO2 luminescence. The reaction propagation leads to the explosion in the microsecond time range that is accompanied by thermal glow of the reaction products with temperature T=4300 K.

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

Treatment outcome of vocal cord leukoplakia by transoral laser microsurgery.

PubMed

Yang, Shih-Wei; Chao, Wei-Chieh; Lee, Yun-Shien; Chang, Liang-Che; Hsieh, Tsan-Yu; Chen, Tai-An; Luo, Cheng-Ming

2017-01-01

The aim of this study is to evaluate the treatment outcome and analyze the associated factors of postoperative recurrence in patients who received transoral laser microsurgery for vocal cord leukoplakia. The demographic, histopathological data were retrospectively reviewed and the factors associated with recurrence of vocal leukoplakia after surgery were analyzed statistically. A total of 44 patients, including 36 males and 8 females, with a mean age of 50.4 ± 13.4 years, were enrolled. All the patients received excision of the vocal leukoplakia by carbon dioxide laser (2-4 Watt, ultrapulse mode) under general anesthesia. No patients had malignant transformation after surgery. Postoperative recurrence occurred in 10 patients (22.7 %). Univariate analysis showed that patients who had the habit of cigarette smoking, alcohol drinking, and presence of gastroesophageal reflux disease tended to recur. Among these risk factors, presence of gastroesophageal reflux disease (odds ratio 8.43) was the independent prognostic factor for recurrence using multivariate logistic regression analysis. Carbon dioxide laser excision is effective for treating vocal leukoplakia that is still confined to dysplasia of any degree, with acceptable morbidity. This study suggests that the presence of gastroesophageal reflux disease is the prognostic indicator for postoperative recurrence of vocal leukoplakia. Aggressive treatment of reflux disease for those who have received surgical excision for vocal leukoplakia is indicated.

Use of a carbon dioxide laser for surgical management of cutaneous masses in horses: 65 cases (1993-2004)

NASA Astrophysics Data System (ADS)

Hawkins, Jan F.; McCauley, Charles T.

2005-04-01

The purpose of this study was to evaluate the outcome of horses treated for cutaneous masses with the carbon dioxide (CO2) laser. The records of 65 horses were examined. Surgery was performed under general anesthesia or standing under sedation and local anesthesia. Excision was performed freehand using a focused beam with power settings ranging from 10 to 32 Watts in a continuous mode. Following en bloc removal of masses the subcutaneous tissue and wound margins were photovaporized using a defocused beam. Follow-up information was obtained via telephone interview with owners or referring veterinarians Cutaneous masses were divided into three groups: sarcoid (29), neoplasia including squamous cell carcinoma (15), melanoma (6), schwanoma (2), fibroma (1), and fibrosarcoma (1), and non-neoplastic masses (11). Mass reoccurrence developed in 8 of 29 (28%) sarcoids and 4 of 14 (29%) squamous cell carcinoma. No reoccurrence was reported for horses diagnosed with melanoma, schwanoma, fibrosarcoma, fibroma, or any of the non-neoplastic masses. Sixty of 63 owners (95%) reported that they were satisfied with the outcome of the procedure. This study demonstrates that the CO2 laser is an effective means of treating cutaneous masses in horses.

New technique for laryngotracheal mucosa transplantation. 'Stamp' welding using indocyanine green dye and albumin interaction with diode laser.

PubMed

Wang, Z; Pankratov, M M; Gleich, L L; Rebeiz, E E; Shapshay, S M

1995-07-01

To investigate (1) the possibility of survival of free mucosa "stamp" grafts fixed in the airway with a new technique using indocyanine green-dyed albumin solder activated with a diode laser and (2) the degree of improvement of wound healing in the airway by applying modified microskin transplantation techniques from burn surgery to cover a relatively large wound with a few small pieces of mucosa anchored in place with the previously mentioned technique. Three (one control and two experimental) rectangular (10 x 8 mm) wounds in tracheal mucosa were produced in four experimental animals (dogs) using a carbon dioxide laser. The control wound was left uncovered. In the first experimental wound, a mucosal flap was raised and then fixed in place by a trapdoor flap method. In the second experimental wound, two small (each 2 x 3 mm) autogenous mucosa grafts were anchored onto the surface with indocyanine green-dyed albumin activated with an 810-nm diode laser. Histomorphologically, the postoperative results from three wounds were compared. The experimental wounds were completely covered by regenerated squamous cells in 1 week and by ciliated epithelium in 2 weeks after the operation despite the discrepancy in size of the graft to wound area (1:6.7) covered with the stamp mucosa. No thermal damage from the diode laser was noted in the second experimental wounds. In the control wounds, no coverage was observed at 1 week, and only squamous cells were noted 2 weeks postoperatively. All the wounds had normal ciliated epithelium coverage at 4 weeks. Transplanted stamp grafts provided similar or better healing than trapdoor flap transplants. This new technique made endoscopic mucosal grafting possible and offers a potential breakthrough in the management of laryngotracheal stenosis.

Laser assisted drug delivery: a review of an evolving technology.

PubMed

Sklar, Lindsay R; Burnett, Christopher T; Waibel, Jill S; Moy, Ronald L; Ozog, David M

2014-04-01

Topically applied drugs have a relatively low cutaneous bioavailability. This article reviews the existing applications of laser assisted drug delivery, a means by which the permeation of topically applied agents can be enhanced into the skin. The existing literature suggests that lasers are a safe and effective means of enhancing the delivery of topically applied agents through the skin. The types of lasers most commonly studied in regards to drug delivery are the carbon dioxide (CO2 ) and erbium:yttrium-aluminum-garnet (Er:YAG) lasers. Both conventional ablative and fractional ablative modalities have been utilized and are summarized herein. The majority of the existing studies on laser assisted drug delivery have been performed on animal models and additional human studies are needed. Laser assisted drug delivery is an evolving technology with potentially broad clinical applications. Multiple studies demonstrate that laser pretreatment of the skin can increase the permeability and depth of penetration of topically applied drug molecules for both local cutaneous and systemic applications. © 2014 Wiley Periodicals, Inc.

Erbium:YAG laser resurfacing increases skin permeability and the risk of excessive absorption of antibiotics and sunscreens: the influence of skin recovery on drug absorption.

PubMed

Lee, Woan-Ruoh; Shen, Shing-Chuan; Al-Suwayeh, Saleh A; Li, Yi-Ching; Fang, Jia-You

2012-06-01

While laser skin resurfacing is expected to result in reduced barrier function and increased risk of drug absorption, the extent of the increment has not yet been systematically investigated. We aimed to establish the skin permeation profiles of tetracycline and sunscreens after exposure to the erbium:yttrium-aluminum-garnet (Er:YAG) laser during postoperative periods. Physiological and histopathological examinations were carried out for 5 days after laser treatment on nude mice. Percutaneous absorption of the permeants was determined by an in vitro Franz cell. Ablation depths varied in reaching the stratum corneum (10 μm, 2.5 J/cm²) to approach the epidermis (25 μm, 6.25 J/cm²) and upper dermis (40 μm, 10 J/cm²). Reepithelialization evaluated by transepidermal water loss was complete within 2-4 days and depended on the ablation depth. Epidermal hyperplasia was observed in the 40-μm-treated group. The laser was sufficient to disrupt the skin barrier and allow the transport of the permeants into and across the skin. The laser fluence was found to play an important role in modulating skin absorption. A 25-μm ablation depth increased tetracycline flux 84-fold. A much smaller enhancement (3.3-fold) was detected for tetracycline accumulation within the skin. The laser with different fluences produced enhancement of oxybenzone skin deposition of 3.4-6.4-fold relative to the untreated group. No penetration across the skin was shown regardless of whether titanium dioxide was applied to intact or laser-treated skin. However, laser resurfacing increased the skin deposition of titanium dioxide from 46 to 109-188 ng/g. Tetracycline absorption had recovered to the level of intact skin after 5 days, while more time was required for oxybenzone absorption. The in vivo skin accumulation and plasma concentration revealed that the laser could increase tetracycline absorption 2-3-fold. The experimental results indicated that clinicians should be cautious when determining the dose for postoperative treatment. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

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.

New and Advanced Picosecond Lasers for Tattoo Removal.

PubMed

Adatto, Maurice A; Amir, Ruthie; Bhawalkar, Jayant; Sierra, Rafael; Bankowski, Richard; Rozen, Doran; Dierickx, Christine; Lapidoth, Moshe

2017-01-01

Early methods of tattoo removal ultimately resulted in unacceptable cosmetic outcomes. While the introduction of laser technology was an improvement over the existing chemical, mechanical, and surgical procedures, the use of nonselective tattoo removal with carbon dioxide and argon lasers led to scarring. Q-switched lasers with nanosecond (10-9) pulse domains were considered to have revolutionized tattoo treatment, by selectively heating the tattoo particles, while reducing the adverse sequelae to adjacent normal skin. Theoretical considerations of restricting pulse duration, to heat tattoo particles to higher temperatures, proposed the use of sub-nanosecond pulses to target particles with thermal relaxation times lower than the nanosecond pulses in Q-switched lasers. Initial studies demonstrated that picosecond (10-12) pulses were more effective than nanosecond pulses in clearing black tattoos. Advances in picosecond technology led to the development of commercially available lasers, incorporating several different wavelengths, to further refine pigment targeting. © 2017 S. Karger AG, Basel.

Fiber lasers and amplifiers for science and exploration at NASA Goddard Space Flight Center

NASA Technical Reports Server (NTRS)

Krainak, Michael A.; Abshire, James; Allan, Graham R.; Stephen Mark

2005-01-01

We discuss present and near-term uses for high-power fiber lasers and amplifiers for NASA- specific applications including planetary topography and atmospheric spectroscopy. Fiber lasers and amplifiers offer numerous advantages for both near-term and future deployment of instruments on exploration and science remote sensing orbiting satellites. Ground-based and airborne systems provide an evolutionary path to space and a means for calibration and verification of space-borne systems. We present experimental progress on both the fiber transmitters and instrument prototypes for ongoing development efforts. These near-infrared instruments are laser sounders and lidars for measuring atmospheric carbon dioxide, oxygen, water vapor and methane and a pseudo-noise (PN) code laser ranging system. The associated fiber transmitters include high-power erbium, ytterbium, neodymium and Raman fiber amplifiers. In addition, we will discuss near-term fiber laser and amplifier requirements and programs for NASA free space optical communications, planetary topography and atmospheric spectroscopy.

Plasma ignition for laser propulsion

NASA Technical Reports Server (NTRS)

Askew, R. F.

1982-01-01

For a specific optical system a pulsed carbon dioxide laser having an energy output of up to 15 joules was used to initiate a plasma in air at one atmosphere pressure. The spatial and temporal development of the plasma were measured using a multiframe image converter camera. In addition the time dependent velocity of the laser supported plasma front which moves opposite to the direction of the laser pulse was measured in order to characterize the type of wavefront developed. Reliable and reproducible spark initiation was achieved. The lifetime of the highly dense plasma at the initial focal spot was determined to be less than 100 nanoseconds. The plasma front propagates toward the laser at a variable speed ranging from zero to 1.6 x 1,000,000 m/sec. The plasma front propagates for a total distance of approximately five centimeters for the energy and laser pulse shape employed.

46 CFR 35.40-7 - Carbon dioxide and clean agent alarms-T/ALL.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 1 2012-10-01 2012-10-01 false Carbon dioxide and clean agent alarms-T/ALL. 35.40-7 Section 35.40-7 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS Posting and Marking Requirements-TB/ALL § 35.40-7 Carbon dioxide and clean agent alarms—T/ALL. Each carbon dioxide or clean agent fire extinguishing alarm...

Thermal stress in dentin and enamel under CO2 laser irradiation

NASA Astrophysics Data System (ADS)

Meyer, Dirk H.; Foth, Hans-Jochen

1996-01-01

Ablation of dentin and tartar was studied under carbon dioxide-laser irradiation in cw and pulse mode with pulse length down to 150 microseconds. The specimens had been cut by a diamant blade to slices of thicknesses between 0.8 and 2.8 mm. The laser induced temperature rise was measured by an infrared camera monitoring the backside of the samples. The specimens shape and structure at the laser spot was analyzed by electron microscopy. Of special interest was the testing of the SwiftLaseTM to reducing the heat. The experimental results show the necessity of a water cooling in all application modes. The origin of the cracks which had been observed in many of the samples, is currently under investigation.

Laser ablation of single-crystalline silicon by radiation of pulsed frequency-selective fiber laser

NASA Astrophysics Data System (ADS)

Veiko, V. P.; Skvortsov, A. M.; Huynh, C. T.; Petrov, A. A.

2015-07-01

We have studied the process of destruction of the surface of a single-crystalline silicon wafer scanned by the beam of a pulsed ytterbium-doped fiber laser radiation with a wavelength of λ = 1062 nm. It is established that the laser ablation can proceed without melting of silicon and the formation of a plasma plume. Under certain parameters of the process (radiation power, beam scan velocity, and beam overlap density), pronounced oxidation of silicon microparticles with the formation of a characteristic loose layer of fine powdered silicon dioxide has been observed for the first time. The range of lasing and beam scanning regimes in which the growth of SiO2 layer takes place is determined.

40 CFR 91.320 - Carbon dioxide analyzer calibration.

Code of Federal Regulations, 2010 CFR

2010-07-01

... monthly thereafter, or within one month prior to the certification test, calibrate the NDIR carbon dioxide... the analyzer to optimize performance. (2) Zero the carbon dioxide analyzer with either purified synthetic air or zero-grade nitrogen. (3) Calibrate on each normally used operating range with carbon...

46 CFR 131.817 - Carbon dioxide warning signs.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 4 2014-10-01 2014-10-01 false Carbon dioxide warning signs. 131.817 Section 131.817 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OFFSHORE SUPPLY VESSELS OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.817 Carbon dioxide warning signs. Each entrance...

46 CFR 131.817 - Carbon dioxide warning signs.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 4 2012-10-01 2012-10-01 false Carbon dioxide warning signs. 131.817 Section 131.817 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OFFSHORE SUPPLY VESSELS OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.817 Carbon dioxide warning signs. Each entrance...

46 CFR 131.817 - Carbon dioxide warning signs.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 4 2013-10-01 2013-10-01 false Carbon dioxide warning signs. 131.817 Section 131.817 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OFFSHORE SUPPLY VESSELS OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.817 Carbon dioxide warning signs. Each entrance...

Effect of Carbon Dioxide Laser on Increasing Vestibular Depth in Cleft Lip and Palate Patients.

PubMed

Yassaei, Sogra; Aghili, Hossein; Azam, Alireza Navab; Moghadam, Mahjobeh Gholdani; Safari, Isa

2017-09-01

Shallow upper buccal sulcus deformity in cleft lip and palate patients is one of the common secondary deformities after primary cleft lip and palate repair; this deformity may prevent or complicate orthodontic and prosthodontic procedures causing aesthetic and functional problems. A number of methods are described to increase the anterior maxillary sulcus in these patients. This study assessed the use of a carbon dioxide laser (CO 2 ) to increase the sulcus depth. Fifteen patients with cleft lip and palate (eight unilateral and seven bilateral) were studied. The surgical procedure was performed using CO 2 laser. The vestibular depth and lip length were measured at three time points namely before surgery (T0), 1 week following surgery (T1), and 4 months following surgery (T2). After data collection, statistical analyses were done using PASW ® version 18 SPSS. The mean values of vestibular depth were 9.46 ± 1.92, 13.83 ± 1.88, and 13.23 ± 1.76 mm for T0, T1, and T2, respectively. The vestibular depth significantly increased after 4 months of follow-up (p = 0.001). The mean amount of vestibular depth gain was not significantly different in unilateral and bilateral cleft groups (p = 0.908). The mean value of upper lip length increased by a mean of 1.23 mm and was statistically significant (p = 0.001). Upper buccal sulcus reconstruction with CO 2 laser provides successful and stable results. CO 2 laser application is suggested as an alternative to conventional vestibuloplasty.

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.

Laser-induced amorphization of silicon during pulsed-laser irradiation of TiN/Ti/polycrystalline silicon/SiO2/silicon

NASA Astrophysics Data System (ADS)

Chong, Y. F.; Pey, K. L.; Wee, A. T. S.; Thompson, M. O.; Tung, C. H.; See, A.

2002-11-01

In this letter, we report on the complex solidification structures formed during laser irradiation of a titanium nitride/titanium/polycrystalline silicon/silicon dioxide/silicon film stack. Due to enhanced optical coupling, the titanium nitride/titanium capping layer increases the melt depth of polycrystalline silicon by more than a factor of 2. It is found that the titanium atoms diffuse through the entire polycrystalline silicon layer during irradiation. Contrary to the expected polycrystalline silicon growth, distinct regions of polycrystalline and amorphous silicon are formed instead. Possible mechanisms for the formation of these microstructures are proposed.

Infrared characteristics of VO2 thin films for smart window and laser protection applications

NASA Astrophysics Data System (ADS)

Huang, Zhangli; Chen, Sihai; Lv, Chaohong; Huang, Ying; Lai, Jianjun

2012-11-01

Vanadium dioxide (VO2) films with a low semiconductor-to-metal transition temperature of 45 °C were fabricated through direct current magnetron sputtering followed by a post-annealing. Atomic force microscopy measurements show that the VO2 grain size is about one hundred of nanometers. Infrared (IR) characteristic is well investigated by applying a He-Ne laser power intensity measurement, and the result reveals that the VO2 film exhibits excellent IR switching property. Furthermore, solar smart window and laser protection experiments demonstrate that the obtained VO2 thin film is a promising material for the application in related fields.

Antares Alignment Gimbal Positioner

NASA Astrophysics Data System (ADS)

Day, R. D.; Viswanathan, V. K.; Saxman, A. C.; Lujan, R. E.; Woodfin, G. L.; Sweatt, W. C.

1981-12-01

Antares is a 24-beam 40-TW carbon-dioxide (CO2) laser fusion system currently under construction at the Los Alamos National Laboratory. The Antares alignment gimbal positioner (AGP) is an optomechanical instrument that will be used for target alignment and alignment of the 24 laser beams, as well as beam quality assessments. The AGP will be capable of providing pointing, focusing, and wavefront optical path difference, as well as aberration information at both helium-neon (He-Ne) and CO2 wavelengths. It is designed to allow the laser beams to be aligned to any position within a 1-cm cube to a tolerance of 10 μm.

46 CFR 97.37-11 - Carbon dioxide warning signs.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 4 2012-10-01 2012-10-01 false Carbon dioxide warning signs. 97.37-11 Section 97.37-11 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS OPERATIONS Markings for Fire and Emergency Equipment, Etc. § 97.37-11 Carbon dioxide warning signs. Each...

46 CFR 97.37-11 - Carbon dioxide warning signs.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 4 2014-10-01 2014-10-01 false Carbon dioxide warning signs. 97.37-11 Section 97.37-11 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS OPERATIONS Markings for Fire and Emergency Equipment, Etc. § 97.37-11 Carbon dioxide warning signs. Each...

46 CFR 97.37-11 - Carbon dioxide warning signs.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 4 2013-10-01 2013-10-01 false Carbon dioxide warning signs. 97.37-11 Section 97.37-11 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS OPERATIONS Markings for Fire and Emergency Equipment, Etc. § 97.37-11 Carbon dioxide warning signs. Each...

Biological Effects of Laser Radiation. Volume III. Effects of Carbon Dioxide Laser Radiation on the Rabbit Eye.

DTIC Science & Technology

1978-10-17

seconds. They reported that enamel In i.rradiated areas was fused, c-halky and opaque. :.-ediately post _adiaticn the irradiated areas, including the...crater, were hot to the touch. Attempts to fuse hydroxyapatite to enamel failed. X-ray diffraction patterns o’ irradiated enamel did not show any...that czscks extended through the eramel and penetrated the dentin. The rod substance of the enamel had been disrpted ,and the inter-rcd substance had

Effects of Beryllium and Compaction Pressure on the Thermal Diffusivity of Uranium Dioxide Fuel Pellets

NASA Astrophysics Data System (ADS)

Camarano, D. M.; Mansur, F. A.; Santos, A. M. M.; Ferraz, W. B.; Ferreira, R. A. N.

2017-09-01

In nuclear reactors, the performance of uranium dioxide (UO2) fuel is strongly dependent on the thermal conductivity, which directly affects the fuel pellet temperature, the fission gas release and the fuel rod mechanical behavior during reactor operation. The use of additives to improve UO2 fuel performance has been investigated, and beryllium oxide (BeO) appears as a suitable additive because of its high thermal conductivity and excellent chemical compatibility with UO2. In this paper, UO2-BeO pellets were manufactured by mechanical mixing, pressing and sintering processes varying the BeO contents and compaction pressures. Pellets with BeO contents of 2 wt%, 3 wt%, 5 wt% and 7 wt% BeO were pressed at 400 MPa, 500 MPa and 600 MPa. The laser flash method was applied to determine the thermal diffusivity, and the results showed that the thermal diffusivity tends to increase with BeO content. Comparing thermal diffusivity results of UO2 with UO2-BeO pellets, it was observed that there was an increase in thermal diffusivity of at least 18 % for the UO2-2 wt% BeO pellet pressed at 400 MPa. The maximum relative expanded uncertainty (coverage factor k = 2) of the thermal diffusivity measurements was estimated to be 9 %.

Measurement of Near-Surface Carbon Dioxide Concentrations with an Open-Path Tunable Diode Laser Sensor and a Non-Dispersive Infrared Sensor at the Bonanza Creek Long Term Ecological Research Site near Fairbanks, Alaska

NASA Astrophysics Data System (ADS)

Bailey, D. M.; Caine, K. M.; Miller, J. H. H.

2016-12-01

Continuous collection of carbon dioxide (CO2) concentrations is imperative in understanding seasonal and inter-annual variability of carbon feedbacks above thawing permafrost. Permafrost makes up one-quarter of the Earth's terrestrial surface and has the potential to release twice the amount of carbon than is currently in the atmosphere if global temperatures continue to increase. A collaborative effort with the University of Alaska - Fairbanks, NASA Goddard Space Flight Center, and our group at George Washington University is underway to monitor these feedbacks near Fairbanks, Alaska. In June 2016, we deployed an open-path tunable diode laser sensor along with a non-dispersive infrared (NDIR) sensor at the Bonanza Creek Long Term Ecological Research Site as an exploratory study for their use in collecting near-surface CO2 concentrations above thawing permafrost. The open-path instrument (OPI) collected spatially-integrated measurements approximately 1.5 meters above the surface of a young thermokarst bog over a 15-day period whereas the NDIR sensor collected localized measurements 1 meter above the surface for 16 days. Near-continuous measurements were achieved with the NDIR sensor which was limited only by the availability of solar-produced power. The OPI measurements were further limited by maintaining laser alignment under changing environmental conditions. However, the campaign achieved a nearly 80% duty cycle for the entire test period. Here we compare both the localized and spatially-integrated carbon dioxide measurements and their observed diurnal concentration cycles, whose magnitude showed a strong dependence on daily weather at the test site.

A robust optical parametric oscillator and receiver telescope for differential absorption lidar of greenhouse gases

NASA Astrophysics Data System (ADS)

Robinson, Iain; Jack, James W.; Rae, Cameron F.; Moncrieff, John B.

2015-10-01

We report the development of a differential absorption lidar instrument (DIAL) designed and built specifically for the measurement of anthropogenic greenhouse gases in the atmosphere. The DIAL is integrated into a commercial astronomical telescope to provide high-quality receiver optics and enable automated scanning for three-dimensional lidar acquisition. The instrument is portable and can be set up within a few hours in the field. The laser source is a pulsed optical parametric oscillator (OPO) which outputs light at a wavelength tunable near 1.6 μm. This wavelength region, which is also used in telecommunications devices, provides access to absorption lines in both carbon dioxide at 1573 nm and methane at 1646 nm. To achieve the critical temperature stability required for a laserbased field instrument the four-mirror OPO cavity is machined from a single aluminium block. A piezoactuator adjusts the cavity length to achieve resonance and this is maintained over temperature changes through the use of a feedback loop. The laser output is continuously monitored with pyroelectric detectors and a custom-built wavemeter. The OPO is injection seeded by a temperature-stabilized distributed feedback laser diode (DFB-LD) with a wavelength locked to the absorption line centre (on-line) using a gas cell containing pure carbon dioxide. A second DFB-LD is tuned to a nearby wavelength (off-line) to provide the reference required for differential absorption measurements. A similar system has been designed and built to provide the injection seeding wavelengths for methane. The system integrates the DFB-LDs, drivers, locking electronics, gas cell and balanced photodetectors. The results of test measurements of carbon dioxide are presented and the development of the system is discussed, including the adaptation required for the measurement of methane.

Measurement of nitrogen dioxide in cigarette smoke using quantum cascade tunable infrared laser differential absorption spectroscopy (TILDAS)

NASA Astrophysics Data System (ADS)

Shorter, Joanne H.; Nelson, David D.; Zahniser, Mark S.; Parrish, Milton E.; Crawford, Danielle R.; Gee, Diane L.

2006-04-01

Although nitrogen dioxide (NO 2) has been previously reported to be present in cigarette smoke, the concentration estimates were derived from kinetic calculations or from measurements of aged smoke, where NO 2 was formed some time after the puff was taken. The objective of this work was to use tunable infrared laser differential absorption spectroscopy (TILDAS) equipped with a quantum cascade (QC) laser to determine if NO 2 could be detected and quantified in a fresh puff of cigarette smoke. A temporal resolution of ˜0.16 s allowed measurements to be taken directly as the NO 2 was formed during the puff. Sidestream cigarette smoke was sampled to determine if NO 2 could be detected using TILDAS. Experiments were conducted using 2R4F Kentucky Reference cigarettes with and without a Cambridge filter pad. NO 2 was detected only in the lighting puff of whole mainstream smoke (without a Cambridge filter pad), with no NO 2 detected in the subsequent puffs. The measurement precision was ˜1.0 ppbV Hz -1/2, which allows a detection limit of ˜0.2 ng in a 35 ml puff volume. More NO 2 was generated in the lighting puff using a match or blue flame lighter (29 ± 21 ng) than when using an electric lighter (9 ± 3 ng). In the presence of a Cambridge filter pad, NO 2 was observed in the gas phase mainstream smoke for every puff (total of 200 ± 30 ng/cigarette) and is most likely due to smoke chemistry taking place on the Cambridge filter pad during the smoke collection process. Nitrogen dioxide was observed continuously in the sidestream smoke starting with the lighting puff.

Laser communication experiment. Volume 1: Design study report: Spacecraft transceiver. Part 1: Transceiver design

NASA Technical Reports Server (NTRS)

1970-01-01

The ATS-F Laser Communications Experiment (LCE) is the first significant step in the application of laser systems to space communications. The space-qualified laser communications system being developed in this experiment, and the data resulting from its successful deployment in space, will be applicable to the use of laser communications systems in a wide variety of manned as well as unmanned space missions, both near earth and in deep space. Particular future NASA missions which can benefit from this effort are the Tracking and Data Relay Satellite System and the Earth Resources Satellites. The LCE makes use of carbon dioxide lasers to establish simultaneous, two-way communication between the ATS-F synchronous satellite and a ground station. In addition, the LCE is designed to permit communication with a similar spacecraft transceiver proposed to be flown on ATS-G, nominally one year after the launch of ATS-F. This would be the first attempt to employ lasers for satellite-to-satellite communications.

Fiber-Based Laser Transmitter at 1.57 Micrometers for Remote Sensing of Atmospheric Carbon Dioxide from Satellites

NASA Technical Reports Server (NTRS)

Yu, Anthony W.; Abshire, James B.; Stephen, Mark A.; Chen, Jeffrey R.; Wu, Stewart; Gonzalez, Brayler; Han, Lawrence; Numata, Kenji; Allan, Graham R.; Hasselbrack, William;

Comparison of Carbon Dioxide Laser With Surgical Blade for Removal of Epulis Fissuratum. A Randomized Clinical Trial

PubMed Central

Karimi, Abbas; Sobouti, Farhad; Torabi, Sara; Bakhshandehfard, Ali; Amirian, Armaghan; Shariati, Mahsa; Morshedi, Ehsan; Barati, Maryam

2016-01-01

Introduction: Epulis fissuratum is often formed as a result of a poor fitting denture. The conventional treatment for this fibrous hyperplastic tissue is to excise it using a scalpel and to close the wound by a continuous or an interrupted suture. The increased utilization of lasers in dentistry also includes the utilization of carbon dioxide (CO2) lasers in place of surgical scalpels in soft tissue surgeries. The objective of this study is to assess the feasibility of utilizing CO2 laser in place of scalpel in surgical treatment of epulis fissuratum. Methods: In this clinical trial research (IRCT code: IRCT2016071124969N2), 19 patients were selected with nearly symmetrical epulis fissuratums in the anterior part of the jaws. The hyperplastic tissue was evenly divided into two sections in each patient. One section was randomly selected and cut by CO2 laser and the other section by a surgical scalpel. The wound created by the scalpel was closed by appropriate number of interrupted sutures. Surgery duration and bleeding as well as vestibular depth, re-epithelialization and edema in both sections were noted and recorded after 7 and 14 days postoperatively. Results: The time of surgery and the amount of bleeding during surgery in the laser section was less and the vestibular depth was more than surgical scalpel section (P < 0.05). Surgical scalpel wound at day seventh healed significantly better than the section treated by the CO2 laser (P < 0.05). Wound in both sections healed similarly on day 14 and no statistical difference was observed. Edema presence was also equal in both sides after 7th and 14th following the surgery. Conclusion: According to the results it could be concluded that the use of CO2 laser may result in less surgery time, less bleeding during surgery, more vestibular depth, better re-epithelialization of the wound and less need for suturing. CO2 laser may be a clinically preferred method for surgical treatment of epulis fissuratum. PMID:28144443

Pseudorandom Noise Code-Based Technique for Cloud and Aerosol Discrimination Applications

NASA Technical Reports Server (NTRS)

Campbell, Joel F.; Prasad, Narasimha S.; Flood, Michael A.; Harrison, Fenton Wallace

2011-01-01

NASA Langley Research Center is working on a continuous wave (CW) laser based remote sensing scheme for the detection of CO2 and O2 from space based platforms suitable for ACTIVE SENSING OF CO2 EMISSIONS OVER NIGHTS, DAYS, AND SEASONS (ASCENDS) mission. ASCENDS is a future space-based mission to determine the global distribution of sources and sinks of atmospheric carbon dioxide (CO2). A unique, multi-frequency, intensity modulated CW (IMCW) laser absorption spectrometer (LAS) operating at 1.57 micron for CO2 sensing has been developed. Effective aerosol and cloud discrimination techniques are being investigated in order to determine concentration values with accuracies less than 0.3%. In this paper, we discuss the demonstration of a PN code based technique for cloud and aerosol discrimination applications. The possibility of using maximum length (ML)-sequences for range and absorption measurements is investigated. A simple model for accomplishing this objective is formulated, Proof-of-concept experiments carried out using SONAR based LIDAR simulator that was built using simple audio hardware provided promising results for extension into optical wavelengths. Keywords: ASCENDS, CO2 sensing, O2 sensing, PN codes, CW lidar

Carbon Dioxide Methanation for Human Exploration of Mars: A Look at Catalyst Longevity and Activity Using Supported Ruthenium

NASA Technical Reports Server (NTRS)

Petersen, Elspeth M.; Meier, Anne J.; Tessonnier, Jean-Philippe

2018-01-01

Overarching Purpose: To design a carbon dioxide methanation/Sabatier reaction catalyst able to withstand variable conditions including fluctuations in bed temperature and feed flow rates for 480 days of remote operation to produce seven tons of methane. Current Study Purpose: Examine supported Ruthenium as a carbon dioxide methanation catalyst to determine the effects support properties have on the active phase by studying activity and selectivity. Objective: The remote operation of the Mars ISRU (In Situ Resources Utilization) lander to produce rocket fuel prior to crew arrival on the planet to power an ascent vehicle. Constraints: Long-term operation (480 days); Variable conditions: Feed gas flow rates, Feed gas flow ratios, Reactor bed temperature.

Experiment definition phase shuttle laboratory (LDRL-10.6 experiment): Shuttle sortie to elliptical orbit satellite

NASA Technical Reports Server (NTRS)

Goodwin, F. E.; Nussmeier, T. A.; Stokes, L. S.; Vourgourakis, E. J.

1976-01-01

The following topics were reviewed: (1) design options for shuttle terminal, (2) elliptical orbit satellite design options, (3) shuttle terminal details, (4) technology status and development requirements, (5) transmitter technology, and (6) carbon dioxide laser life studies.

The Basis for Photocatalytic Writing

ERIC Educational Resources Information Center

Ibanez, Jorge G.; Tausch, Michael W.; Bohrmann-Linde, Claudia; Fernandez-Gallardo, Isabel; Robles-Leyzaola, Ainoha; Krees, Simone; Meuter, Nico; Tennior, Mathias

2011-01-01

We present a demonstration involving the oxidative photobleaching of a raspberry juice dye under visible laser light irradiation using the semiconductor titanium dioxide. A plausible interpretation of the phenomenon is discussed that aids in the understanding of semiconductor energetics and the nature of light. (Contains 2 figures.)

Microgravity Diode Laser Spectroscopy Measurements in a Reacting Vortex Ring

NASA Technical Reports Server (NTRS)

Chen, Shin-Juh; Dahm, Werner J. A.; Silver, Joel A.; Piltch, Nancy D.; VanderWal, R. (Technical Monitor)

2001-01-01

The technique of Diode Laser Spectroscopy (DLS) with wavelength modulation is utilized to measure the concentration of methane in reacting vortex rings under microgravity conditions. From the measured concentration of methane, other major species such as water, carbon dioxide, nitrogen, and oxygen can be easily computed under the assumption of equilibrium chemistry with an iterative method called ITAC (Iterative Temperature with Assumed Chemistry). The conserved scalar approach in modelling the coupling between fluid dynamics and combustion is utilized to represent the unknown variables in terms of the mixture fraction and scalar dissipation rate in conjunction with ITAC. Post-processing of the DLS and the method used to compute the species concentration are discussed. From the flame luminosity results, ring circulation appears to increase the fuel consumption rate inside the reacting vortex ring and the flame height for cases with similar fuel volumes but different ring circulations. The concentrations of methane, water, and carbon dioxide agree well with available results from numerical simulations.

Development of an advanced Two-Micron triple-pulse IPDA lidar for carbon dioxide and water vapor measurements

NASA Astrophysics Data System (ADS)

Petros, Mulugeta; Refaat, Tamer F.; Singh, Upendra N.; Yu, Jirong; Antill, Charles; Remus, Ruben; Taylor, Bryant D.; Wong, Teh-Hwa; Reithmaier, Karl; Lee, Jane; Ismail, Syed; Davis, Kenneth J.

2018-04-01

An advanced airborne triple-pulse 2-μm integrated path differential absorption (IPDA) lidar is under development at NASA Langley Research Center that targets both carbon dioxide (CO2) and water vapor (H2O) measurements simultaneously and independently. This lidar is an upgrade to the successfully demonstrated CO2 2-μm double-pulse IPDA. Upgrades include high-energy, highrepetition rate 2-μm triple-pulse laser transmitter, innovative wavelength control and advanced HgCdTe (MCT) electron-initiated avalanche photodiode detection system. Ground testing and airborne validation plans are presented.

Space-based active optical remote sensing of carbon dioxide column using high-energy two-micron pulsed ipda lidar

NASA Astrophysics Data System (ADS)

Singh, Upendra N.; Refaat, Tamer F.; Ismail, Syed; Petros, Mulugeta; Davis, Kenneth J.; Kawa, Stephan R.; Menzies, Robert T.

2018-04-01

Modeling of a space-based high-energy 2-μm triple-pulse Integrated Path Differential Absorption (IPDA) lidar was conducted to demonstrate carbon dioxide (CO2) measurement capability and to evaluate random and systematic errors. A high pulse energy laser and an advanced MCT e-APD detector were incorporated in this model. Projected performance shows 0.5 ppm precision and 0.3 ppm bias in low-tropospheric column CO2 mixing ratio measurements from space for 10 second signal averaging over Railroad Valley (RRV) reference surface.

Titanium-Dioxide Nano-Fiber-Cotton Targets for Efficient Multi-keV X-Ray Generation

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

Tanabe, M; Nishimura, H; Fujioka, S

Multi-keV x-ray generation from low-density (27 {+-} 7 mg/cc) nano-fiber-cotton targets composed of titanium-dioxide has been investigated. The cotton targets were heated volumetrically and supersonically to a peak electron temperature of 2.3 keV, which is optimal to yield Ti K-shell x rays. Considerable enhancement of conversion efficiency (3.7 {+-} 0.5%) from incident laser energy into Ti K-shell x rays (4-6 keV band) was attained in comparison with that (1.4 {+-} 0.9%) for a planar Ti-foil target.

Titanium dioxide nanofiber-cotton targets for efficient multi-keV x-ray generation

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

Tanabe, Minoru; Nishimura, Hiroaki; Fujioka, Shinsuke

Multi-keV x-ray generation from low-density (27{+-}7 mg/cm{sup 3}) nanofiber-cotton targets composed of titanium dioxide has been investigated. The cotton targets were heated volumetrically and supersonically to a peak electron temperature of 2.3 keV, which is optimal to yield Ti K-shell x rays. Considerable enhancement of conversion efficiency [(3.7{+-}0.5)%] from incident laser energy into Ti K-shell x rays (4-6 keV band) was attained in comparison with that [(1.4{+-}0.9)%] for a planar Ti-foil target.

Ultrafast electron crystallography of the cooperative reaction path in vanadium dioxide

PubMed Central

Yang, Ding-Shyue; Baum, Peter; Zewail, Ahmed H.

2016-01-01

Time-resolved electron diffraction with atomic-scale spatial and temporal resolution was used to unravel the transformation pathway in the photoinduced structural phase transition of vanadium dioxide. Results from bulk crystals and single-crystalline thin-films reveal a common, stepwise mechanism: First, there is a femtosecond V−V bond dilation within 300 fs, second, an intracell adjustment in picoseconds and, third, a nanoscale shear motion within tens of picoseconds. Experiments at different ambient temperatures and pump laser fluences reveal a temperature-dependent excitation threshold required to trigger the transitional reaction path of the atomic motions. PMID:27376103

Enhanced detection of nitrogen dioxide via combined heating and pulsed UV operation of indium oxide nano-octahedra.

PubMed

Gonzalez, Oriol; Roso, Sergio; Vilanova, Xavier; Llobet, Eduard

2016-01-01

We report on the use of combined heating and pulsed UV light activation of indium oxide gas sensors for enhancing their performance in the detection of nitrogen dioxide in air. Indium oxide nano-octahedra were synthesized at high temperature (900 °C) via vapour-phase transport and screen-printed onto alumina transducers that comprised interdigitated electrodes and a heating resistor. Compared to the standard, constant temperature operation of the sensor, mild heating (e.g., 100 °C) together with pulsed UV light irradiation employing a commercially available, 325 nm UV diode (square, 1 min period, 15 mA drive current signal), results in an up to 80-fold enhancement in sensitivity to nitrogen dioxide. Furthermore, this combined operation method allows for making savings in power consumption that range from 35% to over 80%. These results are achieved by exploiting the dynamics of sensor response under pulsed UV light, which convey important information for the quantitative analysis of nitrogen dioxide.

49 CFR 175.900 - Handling requirements for carbon dioxide, solid (dry ice).

Code of Federal Regulations, 2010 CFR

2010-10-01

... (dry ice). 175.900 Section 175.900 Transportation Other Regulations Relating to Transportation PIPELINE....900 Handling requirements for carbon dioxide, solid (dry ice). Carbon dioxide, solid (dry ice) when... operator must ensure that the ground staff is informed that the dry ice is being loaded or is on board the...

49 CFR 175.900 - Handling requirements for carbon dioxide, solid (dry ice).

Code of Federal Regulations, 2013 CFR

2013-10-01

... (dry ice). 175.900 Section 175.900 Transportation Other Regulations Relating to Transportation PIPELINE....900 Handling requirements for carbon dioxide, solid (dry ice). Carbon dioxide, solid (dry ice) when... operator must ensure that the ground staff is informed that the dry ice is being loaded or is on board the...

49 CFR 175.900 - Handling requirements for carbon dioxide, solid (dry ice).

Code of Federal Regulations, 2012 CFR

2012-10-01

... (dry ice). 175.900 Section 175.900 Transportation Other Regulations Relating to Transportation PIPELINE....900 Handling requirements for carbon dioxide, solid (dry ice). Carbon dioxide, solid (dry ice) when... operator must ensure that the ground staff is informed that the dry ice is being loaded or is on board the...

49 CFR 175.900 - Handling requirements for carbon dioxide, solid (dry ice).

Code of Federal Regulations, 2011 CFR

2011-10-01

... (dry ice). 175.900 Section 175.900 Transportation Other Regulations Relating to Transportation PIPELINE....900 Handling requirements for carbon dioxide, solid (dry ice). Carbon dioxide, solid (dry ice) when... operator must ensure that the ground staff is informed that the dry ice is being loaded or is on board the...

49 CFR 175.900 - Handling requirements for carbon dioxide, solid (dry ice).

Code of Federal Regulations, 2014 CFR

2014-10-01

... (dry ice). 175.900 Section 175.900 Transportation Other Regulations Relating to Transportation PIPELINE....900 Handling requirements for carbon dioxide, solid (dry ice). Carbon dioxide, solid (dry ice) when... operator must ensure that the ground staff is informed that the dry ice is being loaded or is on board the...

46 CFR 78.47-11 - Carbon dioxide warning signs.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 3 2014-10-01 2014-10-01 false Carbon dioxide warning signs. 78.47-11 Section 78.47-11 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PASSENGER VESSELS OPERATIONS Markings for Fire and Emergency Equipment, Etc. § 78.47-11 Carbon dioxide warning signs. Each entrance to a space...

46 CFR 78.47-11 - Carbon dioxide warning signs.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 3 2012-10-01 2012-10-01 false Carbon dioxide warning signs. 78.47-11 Section 78.47-11 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PASSENGER VESSELS OPERATIONS Markings for Fire and Emergency Equipment, Etc. § 78.47-11 Carbon dioxide warning signs. Each entrance to a space...

46 CFR 196.37-8 - Carbon dioxide warning signs.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 7 2013-10-01 2013-10-01 false Carbon dioxide warning signs. 196.37-8 Section 196.37-8 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OCEANOGRAPHIC RESEARCH VESSELS OPERATIONS Markings for Fire and Emergency Equipment, etc. § 196.37-8 Carbon dioxide warning signs. Each entrance to a...

46 CFR 196.37-8 - Carbon dioxide warning signs.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 7 2012-10-01 2012-10-01 false Carbon dioxide warning signs. 196.37-8 Section 196.37-8 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OCEANOGRAPHIC RESEARCH VESSELS OPERATIONS Markings for Fire and Emergency Equipment, etc. § 196.37-8 Carbon dioxide warning signs. Each entrance to a...

46 CFR 78.47-11 - Carbon dioxide warning signs.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 3 2013-10-01 2013-10-01 false Carbon dioxide warning signs. 78.47-11 Section 78.47-11 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PASSENGER VESSELS OPERATIONS Markings for Fire and Emergency Equipment, Etc. § 78.47-11 Carbon dioxide warning signs. Each entrance to a space...

46 CFR 196.37-8 - Carbon dioxide warning signs.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 7 2014-10-01 2014-10-01 false Carbon dioxide warning signs. 196.37-8 Section 196.37-8 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OCEANOGRAPHIC RESEARCH VESSELS OPERATIONS Markings for Fire and Emergency Equipment, etc. § 196.37-8 Carbon dioxide warning signs. Each entrance to a...

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.

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).

Flame imaging using planar laser induced fluorescence of sulfur dioxide

NASA Astrophysics Data System (ADS)

Honza, Rene; Ding, Carl-Philipp; Dreizler, Andreas; Böhm, Benjamin

2017-09-01

Laser induced fluorescence of sulfur dioxide (SO2-PLIF) has been demonstrated as a useful tool for flame imaging. Advantage was taken from the strong temperature dependence of the SO2 fluorescence signal. SO2 fluorescence intensity increases by more than one order of magnitude if the temperature changes from ambient conditions to adiabatic flame temperatures of stoichiometric methane-air flames. This results in a steep gradient of SO2-PLIF intensities at the reaction zone and therefore can be used as a reliable flame marker. SO2 can be excited electronically using the fourth-harmonic of an Nd:YAG laser at 266 nm. This is an attractive alternative to OH-LIF, a well-recognized flame front marker, because no frequency-doubled dye lasers are needed. This simplifies the experimental setup and is advantageous for measurements at high repetition rates where dye bleaching can become an issue. To prove the performance of this approach, SO2-PLIF measurements were performed simultaneously with OH-PLIF on laminar premixed methane-air Bunsen flames for equivalence ratios between 0.9 and 1.25. These measurements were compared to 1D laminar flamelet simulations. The SO2 fluorescence signal was found to follow the temperature rise of the flame and is located closer to the steep temperature gradient than OH. Finally, the combined SO2- and OH-PLIF setup was applied to a spark ignition IC-engine to visualize the development of the early flame kernel.

Enhancing caries resistance with a short-pulsed CO2 9.3-μm laser: a laboratory study (Conference Presentation)

NASA Astrophysics Data System (ADS)

Rechmann, Peter; Rechmann, Beate M.; Groves, William H.; Le, Charles; Rapozo-Hilo, Marcia L.; Featherstone, John D. B.

2016-02-01

The objective of this laboratory study was to test whether irradiation with a new 9.3µm microsecond short-pulsed CO2-laser enhances enamel caries resistance with and without additional fluoride applications. 101 human enamel samples were divided into 7 groups. Each group was treated with different laser parameters (Carbon-dioxide laser, wavelength 9.3µm, 43Hz pulse-repetition rate, pulse duration between 3μs to 7μs (1.5mJ/pulse to 2.9mJ/pulse). Using a pH-cycling model and cross-sectional microhardness testing determined the mean relative mineral loss delta Z (∆Z) for each group. The pH-cycling was performed with or without additional fluoride. The CO2 9.3μm short-pulsed laser energy rendered enamel caries resistant with and without additional fluoride use.

Atmospheric effects on CO2 laser propagation

NASA Technical Reports Server (NTRS)

Murty, S. S. R.; Bilbro, J. W.

1978-01-01

An investigation was made of the losses encountered in the propagation of CO2 laser radiation through the atmosphere, particularly as it applies to the NASA/Marshall Space Flight Center Pulsed Laser Doppler System. As such it addresses three major areas associated with signal loss: molecular absorption, refractive index changes in a turbulent environment, and aerosol absorption and scattering. In particular, the molecular absorption coefficients of carbon dioxide, water vapor, and nitrous oxide are calculated for various laser lines in the region of 10.6 mu m as a function of various pressures and temperatures. The current status in the physics of low-energy laser propagation through a turbulent atmosphere is presented together with the analysis and evaluation of the associated heterodyne signal power loss. Finally, aerosol backscatter and extinction coefficients are calculated for various aerosol distributions and the results incorporated into the signal-to-noise ratio equation for the Marshall Space Flight Center system.

Short-pulse laser interactions with disordered materials and liquids

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

Phinney, L.M.; Goldman, C.H.; Longtin, J.P.

High-power, short-pulse lasers in the picosecond and subpicosecond range are utilized in an increasing number of technologies, including materials processing and diagnostics, micro-electronics and devices, and medicine. In these applications, the short-pulse radiation interacts with a wide range of media encompassing disordered materials and liquids. Examples of disordered materials include porous media, polymers, organic tissues, and amorphous forms of silicon, silicon nitride, and silicon dioxide. In order to accurately model, efficiently control, and optimize short-pulse, laser-material interactions, a thorough understanding of the energy transport mechanisms is necessary. Thus, fractals and percolation theory are used to analyze the anomalous diffusion regimemore » in random media. In liquids, the thermal aspects of saturable and multiphoton absorption are examined. Finally, a novel application of short-pulse laser radiation to reduce surface adhesion forces in microstructures through short-pulse laser-induced water desorption is presented.« less

Carbon Dioxide Snow Storms During the Polar Night on Mars

NASA Technical Reports Server (NTRS)

Toon, Owen B.; Colaprete, Anthony

2001-01-01

The Mars Orbiter Laser Altimeter (MOLA) detected clouds associated with topographic features during the polar night on Mars. While uplift generated from flow over mountains initiates clouds on both Earth and Mars, we suggest that the Martian clouds differ greatly from terrestrial mountain wave clouds. Terrestrial wave clouds are generally compact features with sharp edges due to the relatively small particles in them. However, we find that the large mass of condensible carbon dioxide on Mars leads to clouds with snow tails that may extend many kilometers down wind from the mountain and even reach the surface. Both the observations and the simulations suggest substantial carbon dioxide snow precipitation in association with the underlying topography. This precipitation deposits CO2, dust and water ice to the polar caps, and may lead to propagating geologic features in the Martian polar regions.

Laboratory study of adsorption and deliquescence on the surface of Mars

NASA Astrophysics Data System (ADS)

Nikolakakos, George; Whiteway, James A.

2018-07-01

A sample of the zeolitic mineral chabazite was subjected to a range of water vapor pressures and temperatures found on present day Mars. Laser Raman scattering was applied to detect the relative amounts of water and carbon dioxide adsorbed by the sample. Results show that zeolites are capable of adsorbing water from the atmosphere on diurnal time scales and that Raman scattering spectroscopy provides a promising method for detecting this process during a landed mission. When the water vapor pressure and temperature were sufficiently low, the zeolite sample also adsorbed carbon dioxide, resulting in the simultaneous adsorption of water and carbon dioxide on the surface mineral grains. Additional experiments were carried out using a mixture of magnesium perchlorate and chabazite. The sample of mixed surface material remained visually unchanged during water adsorption, but was found to darken during deliquescence.

Development of single shot 1D-Raman scattering measurements for flames

NASA Astrophysics Data System (ADS)

Biase, Amelia; Uddi, Mruthunjaya

2017-11-01

The majority of energy consumption in the US comes from burning fossil fuels which increases the concentration of carbon dioxide in the atmosphere. The increasing concentration of carbon dioxide in the atmosphere has negative impacts on the environment. One solution to this problem is to study the oxy-combustion process. A pure oxygen stream is used instead of air for combustion. Products contain only carbon dioxide and water. It is easy to separate water from carbon dioxide by condensation and the carbon dioxide can be captured easily. Lower gas volume allows for easier removal of pollutants from the flue gas. The design of a system that studies the oxy-combustion process using advanced laser diagnostic techniques and Raman scattering measurements is presented. The experiments focus on spontaneous Raman scattering. This is one of the few techniques that can provide quantitative measurements of the concentration and temperature of different chemical species in a turbulent flow. The experimental design and process of validating the design to ensure the data is accurate is described. The Raman data collected form an experimental data base that is used for the validation of spontaneous Raman scattering in high pressure environments for the oxy-combustion process. NSF EEC 1659710.

Simultaneous and Independent Measurement of Atmospheric Water Vapor and Carbon Dioxide using a Triple-Pulsed, 2-micron Airborne IPDA Lidar - A Feasibility Study

NASA Astrophysics Data System (ADS)

Singh, U. N.; Refaat, T. F.; Yu, J.; Petros, M.

2013-12-01

Water vapor (H2O) and carbon dioxide (CO2) are dominant greenhouse gases that are critical for Earth's radiation budget and global warming through the eco-system and the carbon cycle. NASA Langley Research Center (LaRC) has a strong heritage in atmospheric remote sensing of both gases using several instruments adopting various DIAL techniques. This communication presents a feasibility study for measuring both H2O and CO2 simultaneously and independently using a single instrument. This instrument utilizes the Integrated Path Differential Absorption (IPDA) lidar technique to measure the weighted-average column dry-air mixing ratios of CO2 (XCO2) and H2O (XH2O) independently and simultaneously from an airborne platform. The key component of this instrument is a tunable triple-pulse 2-micron laser. The three laser pulses are transmitted sequentially within a short time interval of 200 microsec. The wavelength of each of the laser pulses can be tuned separately. The IPDA receiver design is based on low-risk, commercially available components, including 300-micron diameter InGaAs 2-micron pin detector, a low-noise, high speed trans-impedance amplifier (TIA) and 12-bit 400 MHz digitizer.

Pulsed Laser Deposited Ferromagnetic Chromium Dioxide thin Films for Applications in Spintronics

NASA Astrophysics Data System (ADS)

Dwivedi, S.; Jadhav, J.; Sharma, H.; Biswas, S.

Stable rutile type tetragonal chromium dioxide (CrO2) thin films have been deposited on lattice-matched layers of TiO2 by KrF excimer laser based pulsed laser deposition (PLD) technique using Cr2O3 target. The TiO2 seed layer was deposited on oxidized Si substrates by the same PLD process followed by annealing at 1100 °C for 4 h. The lattice-matched interfacial layer is required for the stabilization of Cr (IV) phase in CrO2, since CrO2 behaves as a metastable compound under ambient conditions and readily converts into its stable phase of Cr (III) oxide, Cr2O3. Analyses with X-ray diffraction (XRD), Glancing-angle XRD (GIXRD), Raman spectroscopy and grazing-angle Fourier transform infra-red (FTIR) spectroscopy confirm the presence of tetragonal CrO2 phase in the as-deposited films. Microstructure and surface morphology in the films were studied with field emission scanning electron microscope (FESEM) and atomic force microscope (AFM). Electrical and magnetic characterizations of the films were performed at room temperature. Such type of stable half-metallic CrO2 thin films with low field magnetoresistive switching behaviour are in demand for applications as diverse as spin-FETs, magnetic sensors, and magneto-optical devices.

A novel method of carbon dioxide clumped isotope analysis with tunable infra-red laser direct absorption spectroscopy

NASA Astrophysics Data System (ADS)

Prokhorov, Ivan; Kluge, Tobias; Janssen, Christof

2016-04-01

Precise clumped isotopes analysis of carbon dioxide opens up new horizons of atmospheric and biogeochemical research. Recent advances in laser and spectroscopic techniques provides us necessary instrumentation to access extremely low sub-permill variations of multiply-substituted isotopologues. We present an advanced analysis method of carbon dioxide clumped isotopes using direct absorption spectroscopy. Our assessments predict the ultimate precision of the new method on the sub-permill level comparable to state of the art mass spectrometry. Among the most auspicious intrinsic properties of this method we highlight genuine Δ16O13C18O and Δ16O13C18O measurements without isobaric interference, measurement cycle duration of several minutes versus hours for mass spectrometric analysis, reduced sample size of ˜ 10 μmol and high flexibility, allowing us to perform in-situ measurements. The pilot version of the instrument is being developed in an international collaboration framework between Heidelberg University, Germany and Pierre and Marie Curie University, Paris, France. It employs two continuous interband quantum cascade lasers tuned at 4.439 μm and 4.329 μm to measure doubly ( 16O13C18O, 16O13C17O) and singly ( 16O12C16O, 16O13C16O, 16O12C17O, 16O12C18O) substituted isotopologues, respectively. Two identical Herriot cells are filled with dry pure CO2 sample and reference gas at working pressure of 1 - 10 mbar. Cells provide optical path lengths of ˜ 17 m for the laser tuned at doubly substituted isotopologues lines and use a single pass for the laser tuned at the stronger lines of singly substituted isotopologues. Light outside of the gas cells is coupled into optical fiber to avoid absorption by ambient air CO2. Simulations predict sub-permill precision at working pressure of 1 mbar and room temperature stabilised at the ±10 mK level. Our prime target is to apply the proposed method for continuous in-situ analysis of CO2. We are foreseeing potential applications to the following environmental issues: assessments of distinct sources of atmospheric CO2, temperature reconstructions from terrestrial and marine archives, extra-terrestrial atmosphere studies, etc.

Ex vivo investigations of laser auricular cartilage reshaping with carbon dioxide spray cooling in a rabbit model

PubMed Central

Wu, Edward C.; Sun, Victor; Manuel, Cyrus T.; Protsenko, Dmitriy E.; Jia, Wangcun; Nelson, J. Stuart; Wong, Brian J. F.

2014-01-01

Laser cartilage reshaping (LCR) with cryogen spray cooling is a promising modality for producing cartilage shape change while reducing cutaneous thermal injury. However, LCR in thicker tissues, such as auricular cartilage, requires higher laser power, thus increasing cooling requirements. To eliminate the risks of freeze injury characteristic of high cryogen spray pulse rates, a carbon dioxide (CO2) spray, which evaporates rapidly from the skin, has been proposed as the cooling medium. This study aims to identify parameter sets which produce clinically significant reshaping while producing minimal skin thermal injury in LCR with CO2 spray cooling in ex vivo rabbit auricular cartilage. Excised whole rabbit ears were mechanically deformed around a cylindrical jig and irradiated with a 1.45-μm wavelength diode laser (fluence 12–14 J/cm2 per pulse, four to six pulse cycles per irradiation site, five to six irradiation sites per row for four rows on each sample) with concomitant application of CO2 spray (pulse duration 33–85 ms) to the skin surface. Bend angle measurements were performed before and after irradiation, and the change quantified. Surface temperature distributions were measured during irradiation/cooling. Maximum skin surface temperature ranged between 49.0 to 97.6 °C following four heating/cooling cycles. Significant reshaping was achieved with all laser dosimetry values with a 50–70 °C difference noted between controls (no cooling) and irradiated ears. Increasing cooling pulse duration yielded progressively improved gross skin protection during irradiation. CO2 spray cooling may potentially serve as an alternative to traditional cryogen spray cooling in LCR and may be the preferred cooling medium for thicker tissues. Future studies evaluating preclinical efficacy in an in vivo rabbit model are in progress. PMID:23307439

Ex vivo investigations of laser auricular cartilage reshaping with carbon dioxide spray cooling in a rabbit model.

PubMed

Wu, Edward C; Sun, Victor; Manuel, Cyrus T; Protsenko, Dmitriy E; Jia, Wangcun; Nelson, J Stuart; Wong, Brian J F

2013-11-01

Laser cartilage reshaping (LCR) with cryogen spray cooling is a promising modality for producing cartilage shape change while reducing cutaneous thermal injury. However, LCR in thicker tissues, such as auricular cartilage, requires higher laser power, thus increasing cooling requirements. To eliminate the risks of freeze injury characteristic of high cryogen spray pulse rates, a carbon dioxide (CO2) spray, which evaporates rapidly from the skin, has been proposed as the cooling medium. This study aims to identify parameter sets which produce clinically significant reshaping while producing minimal skin thermal injury in LCR with CO2 spray cooling in ex vivo rabbit auricular cartilage. Excised whole rabbit ears were mechanically deformed around a cylindrical jig and irradiated with a 1.45-μm wavelength diode laser (fluence 12-14 J/cm(2) per pulse, four to six pulse cycles per irradiation site, five to six irradiation sites per row for four rows on each sample) with concomitant application of CO2 spray (pulse duration 33-85 ms) to the skin surface. Bend angle measurements were performed before and after irradiation, and the change quantified. Surface temperature distributions were measured during irradiation/cooling. Maximum skin surface temperature ranged between 49.0 to 97.6 °C following four heating/cooling cycles. Significant reshaping was achieved with all laser dosimetry values with a 50-70 °C difference noted between controls (no cooling) and irradiated ears. Increasing cooling pulse duration yielded progressively improved gross skin protection during irradiation. CO2 spray cooling may potentially serve as an alternative to traditional cryogen spray cooling in LCR and may be the preferred cooling medium for thicker tissues. Future studies evaluating preclinical efficacy in an in vivo rabbit model are in progress.

Effect of laser radiation on the cultivation rate of the microalga Chlorella sorokiniana as a source of biofuel

NASA Astrophysics Data System (ADS)

Politaeva, N.; Smyatskaya, Y.; Slugin, V.; Toumi, A.; Bouabdelli, M.

2018-01-01

This article studies the influence of laser radiation on the growth of micro-algal biomass of Chlorella sorokiniana. The composition of nutrient medium and the effect the laser beam (2 and 5 cm diameter, 1, 5, 10, 15 and 20 minutes exposure time) for accelerated cultivation of microalgal biomass were studied. The source of laser radiation (LR) was a helium-neon laser with a nominal output power of 1.6 mW and a wavelength of 0.63 μm. The greatest increase in biomass was observed when LR was applied to a suspension of microalga Chlorella sorokiniana with a beam of 5 cm diameter for a time of 10, 15 and 20 minutes. The results of the microscopic study of the microalga cells show a significant increase in the number of cells after an exposure to LR with a beam diameter of 5 cm in diameter. These cells were characterized by a large vacuole, a thickened lipid shell and a large accumulation of metabolites prone to agglutination. This study proposed to obtain valuable components (lipids, carotenoids, and pectin) from the obtained biomass by extraction method and to use the residual biomass formed wastes, after the extraction of valuable components, as a co-substrate for anaerobic digestion to produce biogas. The composition of biogas consists mainly of methane and carbon dioxide. Methane is recommended to be used for economic needs in supplying the whole process with heat and electricity. The carbon dioxide formed during fermentation and after combustion of methane for energy production, is planned to be used as a carbon source in the cultivation of Chlorella sorokiniana for photoautotrophic biomass production.

Material For Self-Q-Switching Mirrors For Solid State Laser (MSMSSL)

NASA Astrophysics Data System (ADS)

Wolf, L.; Walocha, J.; Drobnik, A.

1983-09-01

Vanadium dioxide (V02) film exhibits semiconductor-to-metal transition at temperature, Tt near 340 K. The transition is accompanied by changes in optical transmission and relection. In this paper the reflected light spectra were experimentally determined at the two temperatures below and above Tt (300 and 360 K) using film thickness as the parameter. Then we calculated the ratio, Kλ , of reflection coefficient, Rm, in metallic phase to reflection coefficient, Rsc, in semiconductor phase. The film for which the maximum Kλ was observed at λ =1.06μm applied as a mirror in Nd:glass laser. The laser generated giant pulse with duration time at about 50 ns.

Antares alignment gimbal positioner

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

Day, R.D.; Viswanathan, V.K.; Saxman, A.C.

1981-01-01

Antares is a 24-beam 40-TW carbon-dioxide (CO/sub 2/) laser fusion system currently under construction at the Los Alamos National Laboratory. The Antares alignment gimbal positioner (AGP) is an optomechanical instrument that will be used for target alignment and alignment of the 24 laser beams, as well as beam quality assessments. The AGP will be capable of providing pointing, focusing, and wavefront optical path difference, as well as aberration information at both helium-neon (He-Ne) and CO/sub 2/ wavelengths. It is designed to allow the laser beams to be aligned to any position within a 1-cm cube to a tolerance of 10more » ..mu..m.« less

Optically pumped carbon dioxide laser mixtures. [using solar radiation

NASA Technical Reports Server (NTRS)

Yesil, O.; Christiansen, W. H.

1979-01-01

This work explores the concept of blackbody radiation pumping of CO2 gas as a step toward utilization of solar radiation as a pumping source for laser action. To demonstrate this concept, an experiment was performed in which laser gas mixtures were exposed to 1500 K thermal radiation for brief periods of time. A gain of 2.8 x 10 to the -3rd reciprocal centimeters has been measured at 10.6 microns in a CO2-He gas mixture of 1 Torr pressure. A simple analytical model is used to describe the rate of change of energy of the vibrational modes of CO2 and to predict the gain. Agreement between the prediction and experiment is good.

Advancements in quantum cascade laser-based infrared microscopy of aqueous media.

PubMed

Haase, K; Kröger-Lui, N; Pucci, A; Schönhals, A; Petrich, W

2016-06-23

The large mid-infrared absorption coefficient of water frequently hampers the rapid, label-free infrared microscopy of biological objects in their natural aqueous environment. However, the high spectral power density of quantum cascade lasers is shifting this limitation such that mid-infrared absorbance images can be acquired in situ within signal-to-noise ratios of up to 100. Even at sample thicknesses well above 50 μm, signal-to-noise ratios above 10 are readily achieved. The quantum cascade laser-based microspectroscopy of aqueous media is exemplified by imaging an aqueous yeast solution and quantifying glucose consumption, ethanol generation as well as the production of carbon dioxide gas during fermentation.

Mathematical simulation of the amplification of 1790-nm laser radiation in a nuclear-excited He - Ar plasma containing nanoclusters of uranium compounds

NASA Astrophysics Data System (ADS)

Kosarev, V. A.; Kuznetsova, E. E.

2014-02-01

The possibility of applying dusty active media in nuclearpumped lasers has been considered. The amplification of 1790-nm radiation in a nuclear-excited dusty He - Ar plasma is studied by mathematical simulation. The influence of nanoclusters on the component composition of the medium and the kinetics of the processes occurring in it is analysed using a specially developed kinetic model, including 72 components and more than 400 reactions. An analysis of the results indicates that amplification can in principle be implemented in an active laser He - Ar medium containing 10-nm nanoclusters of metallic uranium and uranium dioxide.

46 CFR 196.37-9 - Carbon dioxide and clean agent alarms.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 7 2013-10-01 2013-10-01 false Carbon dioxide and clean agent alarms. 196.37-9 Section 196.37-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OCEANOGRAPHIC RESEARCH VESSELS OPERATIONS Markings for Fire and Emergency Equipment, etc. § 196.37-9 Carbon dioxide and clean agent alarms. Each extinguishing system using...

46 CFR 196.37-9 - Carbon dioxide and clean agent alarms.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 7 2012-10-01 2012-10-01 false Carbon dioxide and clean agent alarms. 196.37-9 Section 196.37-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OCEANOGRAPHIC RESEARCH VESSELS OPERATIONS Markings for Fire and Emergency Equipment, etc. § 196.37-9 Carbon dioxide and clean agent alarms. Each extinguishing system using...

46 CFR 196.37-9 - Carbon dioxide and clean agent alarms.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 7 2014-10-01 2014-10-01 false Carbon dioxide and clean agent alarms. 196.37-9 Section 196.37-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OCEANOGRAPHIC RESEARCH VESSELS OPERATIONS Markings for Fire and Emergency Equipment, etc. § 196.37-9 Carbon dioxide and clean agent alarms. Each extinguishing system using...

46 CFR 35.40-8 - Carbon dioxide warning signs-T/ALL.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 1 2012-10-01 2012-10-01 false Carbon dioxide warning signs-T/ALL. 35.40-8 Section 35.40-8 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS Posting and Marking Requirements-TB/ALL § 35.40-8 Carbon dioxide warning signs—T/ALL. Each entrance to a space storing...

40 CFR 60.44c - Compliance and performance test methods and procedures for sulfur dioxide.

Code of Federal Regulations, 2011 CFR

2011-07-01

... and procedures for sulfur dioxide. 60.44c Section 60.44c Protection of Environment ENVIRONMENTAL... Compliance and performance test methods and procedures for sulfur dioxide. (a) Except as provided in... operator seeks to demonstrate compliance with the fuel oil sulfur limits under § 60.42c based on shipment...

40 CFR 60.44c - Compliance and performance test methods and procedures for sulfur dioxide.

Code of Federal Regulations, 2012 CFR

2012-07-01

... and procedures for sulfur dioxide. 60.44c Section 60.44c Protection of Environment ENVIRONMENTAL... Compliance and performance test methods and procedures for sulfur dioxide. (a) Except as provided in... operator seeks to demonstrate compliance with the fuel oil sulfur limits under § 60.42c based on shipment...

40 CFR 49.129 - Rule for limiting emissions of sulfur dioxide.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 1 2013-07-01 2013-07-01 false Rule for limiting emissions of sulfur... emissions of sulfur dioxide. (a) What is the purpose of this section? This section limits the amount of sulfur dioxide (SO2) that may be emitted from certain air pollution sources operating within the Indian...

40 CFR 60.44c - Compliance and performance test methods and procedures for sulfur dioxide.

Code of Federal Regulations, 2014 CFR

2014-07-01

... and procedures for sulfur dioxide. 60.44c Section 60.44c Protection of Environment ENVIRONMENTAL... Compliance and performance test methods and procedures for sulfur dioxide. (a) Except as provided in... operator seeks to demonstrate compliance with the fuel oil sulfur limits under § 60.42c based on shipment...

40 CFR 60.44c - Compliance and performance test methods and procedures for sulfur dioxide.

Code of Federal Regulations, 2013 CFR

2013-07-01

... and procedures for sulfur dioxide. 60.44c Section 60.44c Protection of Environment ENVIRONMENTAL... Compliance and performance test methods and procedures for sulfur dioxide. (a) Except as provided in... operator seeks to demonstrate compliance with the fuel oil sulfur limits under § 60.42c based on shipment...

In-situ measurement of residence time distributions in a turbulent oxy-fuel gas-flame combustor

NASA Astrophysics Data System (ADS)

Bürkle, Sebastian; Becker, Lukas G.; Agizza, Maria Angela; Dreizler, Andreas; Ebert, Volker; Wagner, Steven

2017-07-01

For improving the design of combustors, the knowledge of residence-time distributions (RTD) is important as they influence exhaust gas compositions. Measuring RTDs in combustors is challenging, due to high temperatures, chemical reactions, the presence of particles or corrosive species as well as high turbulence levels. This paper presents a technique for the in situ measurement of RTDs in combustors. Based on tunable diode laser absorption spectroscopy (TDLAS), the temporal evolution of the concentration of tracers is tracked simultaneously at the combustion chamber inlet and outlet. Using either air or mixtures of oxygen and carbon dioxide (oxy-fuel atmosphere) as oxidants, the method is applied to reacting and non-reacting operating conditions in a 20-kWth methane combustor. For reacting conditions, hydrogen chloride is used as a tracer, whereas for non-reacting conditions methane was chosen. Depending on the tracer, for a repetition rate of approximately 2 kHz detection limits of 16-40 ppmV are achieved. For deriving RTDs, low-pass filtering is compared to reactor network modeling. Different RTDs observed for varying operating conditions are discussed.

Effect of basic fibroblast growth factor and transforming growth factor β1 on the healing of reconstructed dura by carbon dioxide laser soldering in minipigs.

PubMed

Zhong, Hong-liang; Wang, Zhen-min; Yang, Zhi-jun; Zhao, Fu; Wang, Bo; Wang, Zhong-cheng; Liu, Pi-nan

2012-02-01

Carbon dioxide (CO2) laser soldering is an alternative technique for tissue bonding. Basic fibroblast growth factor (bFGF) and transforming growth factor β(1) (TGFβ(1)) are two key factors for wound healing. This study was performed to demonstrate the efficacy of CO2 laser soldering for dural reconstruction and the effect of bFGF and TGFβ(1) on healing. In Part I, 10 minipigs were randomized into two equal groups. Dural defects were reconstructed by conventional fibrin glue bonding (group I(a)) or CO2 laser soldering (group I(b)). The reconstructed dura was subjected to burst pressure (BP) measurement and immunohistochemical staining after 1 week. In Part II, 36 minipigs were randomized into three equal groups. Dural reconstruction was achieved by CO2 laser soldering. Exogenous bFGF (group II(b)) or TGFβ(1) (group II(c)) was administered while group II(a) served as a control group. The specimens were subjected to BP measurement after 1, 2, 3, and 4 weeks, respectively. In Part I, the dura specimens displayed positive staining of only bFGF in group I(a) and of both bFGF and TGFβ(1) in group I(b). Group I(b) showed higher BP than group I(a) ((98.00 ± 21.41) mmHg vs. (70.80 ± 15.09) mmHg, respectively; P < 0.05). In Part II, BP of group II(c) was significantly higher than that of group II(a) (P < 0.01). The BP of group II(a) trended toward stabilization after 3 weeks of growth, while that of groups II(b) and II(c) trended toward stabilization after 2 weeks of growth. CO2 laser soldering is a reliable technique for dural reconstruction. The superior healing of dural reconstruction by CO2 laser soldering may be related to higher expression of bFGF and TGFβ(1), and CO2 lasers may stimulate their secretion. Exogenous bFGF or TGFβ(1) may improve healing by shortening the wound healing time, and exogenous TGFβ(1) may improve the tensile strength.

Investigation into the absorptivity change in metals with increased laser power

NASA Astrophysics Data System (ADS)

Blidegn, M. Sc. K.; Olsen, Flemming O.

1997-04-01

At first glance the low absorptivity of metals in the infrared (IR) makes the use of YAG or carbon-dioxide lasers in metal processing very inefficient. However, it has been demonstrated that the absorptivity can reach significantly higher levels during the high power laser interaction. An increase which cannot be explained by the increase in temperature only. The interaction between laser light and metals is a major physical phenomena in laser material processing and when modeling processes the Drude free electron model or simplifications, such as the Hagen-Rubens relation, have often been used. This paper discusses the need to extend the Drude model taking into account interband transitions and anormal skin effect at low light intensities and a multiphoton absorption model in order to describe the increase in the absorptivity at high intensities. The model is compared with experimental results carried out at low power, and tested on experimental absorptivity measurements at high power YAG laser pulses, found in literature.

A systematic review of the use of lasers for the treatment of hidradenitis suppurativa.

PubMed

John, Hannah; Manoloudakis, Nikolaos; Stephen Sinclair, J

2016-10-01

To conduct a systematic review of the effectiveness of various types of lasers (and light based therapies) for the treatment of hidradenitis suppurativa (HS) and to establish recommendations based on our findings. MEDLINE, Cochrane and PubMed databases. English language studies describing the use of laser for the treatment of HS. Multiple reviewers performed independent extraction and identified 22 studies that met the inclusion and exclusion criteria. Studies were categorised according to grading recommendations based on evidence quality guidelines for systematic reviews. Only 2 studies met criteria to be assigned the highest grade. Nd:YAG laser has been shown to be effective for the treatment of HS, as is intense pulsed light therapy (IPL) using the same principles of laser hair removal. There is weak evidence to recommend the use of carbon dioxide, diode or alexandrite lasers. The need for larger randomized controlled trials is highlighted. Copyright © 2016 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Determination of the plasma impedance of a glow discharge in carbon dioxide

NASA Astrophysics Data System (ADS)

Kiselev, A. S.; Smirnov, E. A.

2017-07-01

In this work an expression for the dynamic resistance of a glow discharge flowing in long tubes is obtained and analyzed. The expression describes the physical processes occurring in the positive column of a glow discharge. The frequency dependences of the active and reactive components as well as the dynamic resistance module for the discharge conditions corresponding to CO2-lasers have been calculated. Based on the simulation results developed a computer program in the C# programming language for modeling the dynamic resistance discharge of glow discharge lasers.

Aesthetic management of gingival recession by root biomodification with carbon dioxide laser and subepithelial connective tissue graft with lateral repositioned flap technique

PubMed Central

Rastogi, Pavitra Kumar; Lal, Nand; Garg, Nimit; Anand, Vishal; Singhal, Rameshwari

2012-01-01

Localised gingival recessions continue to represent an important aesthetic condition requiring treatment in periodontics. Various techniques have been tried to treat exposed root surfaces to improve aesthetics with high percentage of success and minimal discomfort. Root biomodification is done to improve the predictability of these procedures. This clinical report describes periodontal plastic procedure involving subepithelial connective tissue graft with lateral repositioned flap technique and root biomodification with CO2 laser for the management of gingival recession. PMID:22778454

Nonlinear Spectroscopy of Multicomponent Droplets and Two- and Three-Dimensional Measurements in Flames

DTIC Science & Technology

1989-01-27

carbon dioxide laser has caused the droplet to undergo vaporization. --- - -(tont-nued) 20. DISTRIBUTION /AVAILABIUTV OF ATRACT 21. ABSTRACT SECURITY...breakdown threshold and produced a dense, high temperature plasma which can abosrb the stimulated Raman radiation; (3) studies on the dependence of the

Physics at the International Science and Engineering Fair.

ERIC Educational Resources Information Center

Walker, Jearl

1979-01-01

A judge for the physics projects for the 1979 International Science and Engineering Fair describes many of the more popular science projects. Projects described include the following: carbon dioxide and helium-neon lasers, reverse flame investigations, holography, construction of a magnetic bottle to confine plasma, and aerodynamic drag. (BT)

40 CFR 86.1324-84 - Carbon dioxide analyzer calibration.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Exhaust Test Procedures § 86.1324-84 Carbon dioxide analyzer calibration. Prior to its introduction into...) Follow good engineering practices for instrument start-up and operation. Adjust the analyzer to optimize...

Test stand for gas-discharge chamber of TEA CO2 lasers with pulse-periodical energy supply

NASA Astrophysics Data System (ADS)

Shorin, Vladimyr P.; Bystrov, N. D.; Zhuravlyov, O. A.; Nekrasov, V. V.

1997-05-01

Test stand for function optimization (incomposition of gas- dynamic circuit (GDC) of operating characteristics of full- size discharge chamber of flowing TEA carbon-dioxide lasers (power up to 100 kW) was created in Samara State Aerospace University (former Kuibyshev Aviation Institute). Test stand includes an inside-type GDC, low inductive generators of voltage pulses of preionization and main discharges, two-flow rate system of gas supply and noise immunity diagnostic system. Module construction of units of GDC, power supplies of preionization and main discharges allows to change configuration of stand's systems for providing given properties of gas flow and its energy supply. This test stand can also be used in servicing of laser system. The diagnostic system of this stand allows us to analyze energy properties of discharge by means of oscillographic measurements of voltage and current with following processing of discharges' volt- ampere characteristics by means of a computer; rate of non- stationary gas-dynamic disturbances in discharge gap of discharge chamber was measured by means of pulse holographic system (UlG-1M) with data processing of schliren- and interferogram (density fluctuation sensitivity approximately 10-2) and sensor measurement system of gas-dynamic shock and acoustics process with resonance frequency exceeding 100 kHz. Research results of process of plasma plate wave and channel structures interaction with mediums, including actuation non-stationary gas-dynamic flows, cavitation erosion of preionization electrodes' dielectric substructure, ancillary heating of channels by main volumetric discharge are presented as well.

Triple-Pulse Integrated Path Differential Absorption Lidar for Carbon Dioxide Measurement - Novel Lidar Technologies and Techniques with Path to Space

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Refaat, Tamer F.; Petros, Mulugeta

2017-01-01

The societal benefits of understanding climate change through identification of global carbon dioxide sources and sinks led to the desired NASA's active sensing of carbon dioxide emissions over nights, days, and seasons (ASCENDS) space-based missions of global carbon dioxide measurements. For more than 15 years, NASA Langley Research Center (LaRC) have developed several carbon dioxide active remote sensors using the differential absorption lidar (DIAL) technique operating at the two-micron wavelength. Currently, an airborne two-micron triple-pulse integrated path differential absorption (IPDA) lidar is under development. This IPDA lidar measures carbon dioxide as well as water vapor, the dominant interfering molecule on carbon dioxide remote sensing. Advancement of this triple-pulse IPDA lidar development is presented.

Preliminary study on the treatment of vitiligo with carbon dioxide fractional laser together with tacrolimus.

PubMed

Chen, Wei; Zhou, Yuan; Huang, Fei-Ran; Luo, Dan; Wang, Da-Guang

2018-04-10

Tacrolimus is a conventional medication for the treatment of vitiligo, but the effect of a single medication is limited. This paper aims at observing the effects, adverse responses, and repigmentation results of the joint treatment of vitiligo by Carbon dioxide (CO 2 ) fractional laser together with tacrolimus. Forty-five patients with vitiligo were randomly divided into two groups: treatment (T) group and control (C) group, and each group was further divided into three subgroups (face, torso and limbs, and hand and foot) according to the location of the skin defect. Both groups used topical 0.1% tacrolimus cream, but the T group was given one CO 2 fractional laser treatment each month. We observed the clinical efficacy, adverse responses, and repigmentation results after 6 months. Compared to the C group, the T group showed better improvement in both objective and subjective assessments. When the treatment time was increased, the efficacy was also improved, and the repigmentation in the T group occured in three ways: perifollicular repigmentation, marginal repigmentation and diffuse repigmentation. There were three cases of isomorphic responses (2 cases in the rapid progression stage, one case in the progression stage), and 1 case formed scarring on the neck in the T group. The treatment of vitiligo by CO 2 fractional laser together with tacrolimus is significantly effective and is most suitable for patients in the progression stage. Patients in the rapid progression stage should use this approach with caution, and its efficacy was limited for patients in the stable stage. An extended course of treatment is helpful for the repigmentation of white patches. All three forms of repigmentation can occur in the joint treatment of vitiligo by CO 2 fractional laser together with tacrolimus. Lasers Surg. Med. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

The efficacy of fractional carbon dioxide (CO2) laser combined with terbinafine hydrochloride 1% cream for the treatment of onychomycosis.

PubMed

Shi, Jian; Li, Jin; Huang, He; Permatasari, Felicia; Liu, Juan; Xu, Yang; Wu, Di; Zhou, Bing-Rong; Luo, Dan

2017-10-01

Although systemic and topical antifungal agents are widely used to treat onychomycosis, oral medications can cause adverse effects and the efficacy of topical agents is not satisfying. Currently, laser treatment has been studied for its efficacy in the treatment of onychomycosis. Our study was aimed to evaluate the efficacy of fractional carbon dioxide (CO 2 ) laser treatment combined with terbinafine cream for 6 months in the treatment of onychomycosis and to analyze the influencing factors. A total of 30 participants (124 nails) with clinical and mycological diagnosis of onychomycosis received fractional CO 2 laser treatment at 2-week interval combined with terbinafine cream once daily for 6 months. The clinical efficacy rate (CER) was assessed from the percentage of fully normal-appearing nails or nails with ≤5% abnormal appearance, and the mycological clearance rate (MCR) was assessed from the percentage of nails with negative fungal microscopy. The CER was evaluated at 3 time points: at the end of treatment (58.9%), at 1 month after the last treatment (63.5%), and at 3 months after the last treatment (68.5%). The MCRs at 1 month and 3 months after the last treatment were 77.4 and 74.2%, respectively. The evaluation of influencing factors showed significantly higher CER (p < 0.05) in nails of participants with age <50 years, distal lateral subungual onychomycosis (DLSO), superficial white onychomycosis (SWO), nail thickness <2 mm, affected first-to-fourth finger/toenails, Trichophyton rubrum, and Trichophyton mentagrophytes. All participants experienced tolerable mild burning sensation during laser treatment, but there were no other adverse reactions reported. Fractional CO 2 laser treatment combined with terbinafine cream for 6 months was an effective and safe method for the treatment of onychomycosis. There were 5 factors that positively influenced the treatment outcome: age, clinical type of onychomycosis, nail thickness, involved nail, and species of fungus.

Pressure and Temperature Changes in In Vitro Applications with the Laser and Their Implications for Middle Ear Surgery

PubMed Central

Schwab, Burkard; Kontorinis, Georgios

2010-01-01

Background. The purpose of this study was to evaluate the thermal and pressure effects using a Titan Sapphire chirped-pulse amplifier system configured to deliver ultrashort pulses of 180 femtoseconds (fs) in an inner ear model. Materials and Methods. Temperature increases and heat exchange processes in the fluid (physiological saline) were examined in a calorically and physiologically approximated cochlea model for applying laser parameters effective in the creation of footplate perforations. Results. In the effective energy density range, the highest temperature increases achieved with the Carbon dioxide (CO2) laser were about 11 degrees C. The lowest temperature maxima were 6 degrees C with the Er:YAG laser (Yttrium-Aluminum-Oxide doted with Erbium3+-ions) and <5 degrees C with the femtosecond laser. Comparison of the laser-induced pressure with the limit graph published by Pfander indicated that the use of the fs laser is unobjectionable for fluences <1 J/cm2. Conclusions. Our investigations demonstrated that the application of the fs laser in middle ear surgery presents a new and promising addition to the range of ultrashort wavelength lasers used for this purpose. PMID:20953354

He-Ne and CW CO2 laser long-path systems for gas detection

NASA Technical Reports Server (NTRS)

Grant, W. B.

1986-01-01

This paper describes the design and testing of a laboratory prototype dual He-Ne laser system for the detection of methane leaks from underground pipelines and solid-waste landfill sites using differential absorption of radiation backscattered from topographic targets. A laboratory-prototype dual CW carbon dioxide laser system also using topographic backscatter is discussed, and measurement results for methanol are given. With both systems, it was observed that the time-varying differential absorption signal was useful in indicating the presence of a gas coming from a nearby source. Limitations to measurement sensitivity, especially the role of speckle and atmospheric turbulence, are described. The speckle results for hard targets are contrasted with those from atmospheric aerosols. The appendix gives appropriate laser lines and values of absorption coefficients for the hydrazine fuel gases.

MASERATI: a RocketBorne tunable diode laser absorption spectrometer.

PubMed

Lübken, F J; Dingler, F; von Lucke, H; Anders, J; Riedel, W J; Wolf, H

1999-09-01

The MASERATI (middle-atmosphere spectrometric experiment on rockets for analysis of trace-gas influences) instrument is, to our knowledge, the first rocket-borne tunable diode laser absorption spectrometer that was developed for in situ measurements of trace gases in the middle atmosphere. Infrared absorption spectroscopy with lead salt diode lasers is applied to measure water vapor and carbon dioxide in the altitude range from 50 to 90 km and 120 km, respectively. The laser beams are directed into an open multiple-pass absorption setup (total path length 31.7 m) that is mounted on top of a sounding rocket and that is directly exposed to ambient air. The two species are sampled alternately with a sampling time of 7.37 ms, each corresponding to an altitude resolution of approximately 15 m. Frequency-modulation and lock-in techniques are used to achieve high sensitivity. Tests in the laboratory have shown that the instrument is capable of detecting a very small relative absorbance of 10(-4)-10(-5) when integrating spectra for 1 s. The instrument is designed and qualified to resist the mechanical stress occurring during the start of a sounding rocket and to be operational during the cruising phase of the flight when accelerations are very small. Two almost identical versions of the MASERATI instrument were built and were launched on sounding rockets from the Andøya Rocket Range (69 degrees N) in northern Norway on 12 October 1997 and on 31 January 1998. The good technical performance of the instruments during these flights has demonstrated that MASERATI is indeed a new suitable tool to perform rocket-borne in situ measurements in the upper atmosphere.

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.

Orthogonally superimposed laser-induced periodic surface structures (LIPSS) upon nanosecond laser pulse irradiation of SiO2/Si layered systems

NASA Astrophysics Data System (ADS)

Nürnberger, Philipp; Reinhardt, Hendrik M.; Kim, Hee-Cheol; Pfeifer, Erik; Kroll, Moritz; Müller, Sandra; Yang, Fang; Hampp, Norbert A.

2017-12-01

In this study we examined the formation of laser-induced periodic surface structures (LIPSS) on silicon (Si) in dependence on the thickness of silicon-dioxide (SiO2) on top. LIPSS were generated in air by linearly polarized ≈8 nanosecond laser pulses with a fluence per pulse of 2.41 J cm-2 at a repetition rate of 100 kHz. For SiO2 layers <80 nm, LIPSS oriented perpendicular to the laser polarization were obtained, but for SiO2 layers >120 nm parallel oriented LIPSS were observed. In both cases the periodicity was about 80-90% of the applied laser wavelength (λ0 = 532 nm). By variation of the SiO2 layer thickness in the range between 80 nm-120 nm, the dominating orientation changes. Even orthogonally superimposed LIPSS with a periodicity of only 60% of the laser wavelength were found. We show that the transition of the orientation direction of LIPSS is related to the penetration depth of surface plasmon polariton (SPP) fields into the oxide layer.

Nd:GdVO4 ring laser pumped by laser diodes

NASA Astrophysics Data System (ADS)

Hao, E. J.; Li, T.; Wang, Z. D.; Zhang, Y.

2013-02-01

The design and operation of a laser diode-pumped Nd:GdVO4 ring laser is described. A composite crystal (Nd:GdVO4/YVO4) with undoped ends is single-end pumped by a fiber-coupled laser diode (LD) at 808 nm. A four-mirror ring cavity is designed to keep the laser operating unidirectionally, which eliminates spatial hole burning in the standing-wave cavity. This laser can operate either as continuous wave (CW) or Q-switched. The single-frequency power obtained was 9.1 W at 1063 nm. Q-switched operation produced 0.23 mJ/pulse at 20 kHz in the fundamental laser.

Rare isotope studies involving catalytic oxidation of CO over platinum-tin oxide

NASA Technical Reports Server (NTRS)

Upchurch, Billy T.; Wood, George M., Jr.; Hess, Robert V.; Hoyt, Ronald F.

1987-01-01

Results of studies utilizing normal and rare oxygen isotopes in the catalytic oxidation of carbon monoxide over a platinum-tin oxide catalyst substrate are presented. Chemisorption of labeled carbon monoxide on the catalyst followed by thermal desorption yielded a carbon dioxide product with an oxygen-18 composition consistent with the formation of a carbonate-like intermediate in the chemisorption process. The efficacy of a method developed for the oxygen-18 labeling of the platinum-tin oxide catalyst surface for use in closed cycle pulsed care isotope carbon dioxide lasers is demonstrated for the equivalent of 10 to the 6th power pulses at 10 pulses per second.

Carbon dioxide conversion over carbon-based nanocatalysts.

PubMed

Khavarian, Mehrnoush; Chai, Siang-Piao; Mohamed, Abdul Rahman

2013-07-01

The utilization of carbon dioxide for the production of valuable chemicals via catalysts is one of the efficient ways to mitigate the greenhouse gases in the atmosphere. It is known that the carbon dioxide conversion and product yields are still low even if the reaction is operated at high pressure and temperature. The carbon dioxide utilization and conversion provides many challenges in exploring new concepts and opportunities for development of unique catalysts for the purpose of activating the carbon dioxide molecules. In this paper, the role of carbon-based nanocatalysts in the hydrogenation of carbon dioxide and direct synthesis of dimethyl carbonate from carbon dioxide and methanol are reviewed. The current catalytic results obtained with different carbon-based nanocatalysts systems are presented and how these materials contribute to the carbon dioxide conversion is explained. In addition, different strategies and preparation methods of nanometallic catalysts on various carbon supports are described to optimize the dispersion of metal nanoparticles and catalytic activity.

Laser treatment of cutaneous angiokeratomas: A systematic review.

PubMed

Nguyen, Jannett; Chapman, Lance W; Korta, Dorota Z; Zachary, Christopher B

2017-11-01

Angiokeratomas can present therapeutic challenges, especially in cases of extensive lesions, where traditional surgical methods carry high risks of scarring and hemorrhage. Argon, pulsed dye (PDL), neodymium-doped yttrium aluminum garnet (Nd:YAG), copper vapor, potassium titanyl phosphate, carbon dioxide, and erbium-doped yttrium aluminum garnet (Er:YAG) lasers have emerged as alternative options. To review the use and efficacy of lasers in treating angiokeratomas. A PubMed search identified randomized clinical trials, cohort studies, case series, and case reports involving laser treatment of cutaneous angiokeratomas. Twenty-five studies were included. Quality ratings were assigned using the Oxford Centre for Evidence-Based Medicine scheme. Several laser modalities are effective in treating multiple variants of angiokeratomas. Vascular lasers like PDL, Nd:YAG, and argon are the most studied and of these, PDL offers the safest side effect profile. Nd:YAG may be more effective for hyperkeratotic angiokeratomas. Combination treatment with multiple laser modalities has also demonstrated some success. Lasers are a promising treatment option for angiokeratomas, but current use is limited by the lack of treatment guidelines. There are limited high quality studies comparing laser treatments to each other and to non-laser options. Additional studies are needed to establish guidelines and to optimize laser parameters. © 2017 Wiley Periodicals, Inc.

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.

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.

CO2 Compressor Requirements for Integration of Space Station Carbon Dioxide Removal and Carbon Dioxide Reduction Assemblies

NASA Technical Reports Server (NTRS)

Jeng, Frank F.; Lewis, John F.; Graf, John; LaFuse, Sharon; Nicholson, Leonard S. (Technical Monitor)

1999-01-01

This paper describes the analysis on integration requirements, CO2 compressor in particular, for integration of Carbon Dioxide Removal Assembly (CDRA) and CO2 Reduction Assembly (CRA) as a part of the Node 3 project previously conducted at JSC/NASA. A system analysis on the volume and operation pressure range of the CO2 accumulator was conducted. The hardware and operational configurations of the CO2 compressor were developed. The performance and interface requirements of the compressor were specified. An existing Four-Bed Molecular Sieve CO2 removal computer model was modified into a CDRA model and used in analyzing the requirements of the CDRA CO2 compressor. This CDRA model was also used in analyzing CDRA operation parameters that dictate CO2 pump sizing. Strategy for the pump activation was also analyzed.

Strained-layer indium gallium arsenide-gallium arsenide- aluminum galium arsenide photonic devices by metalorganic chemical vapor deposition

NASA Astrophysics Data System (ADS)

Osowski, Mark Louis

With the arrival of advanced growth technologies such as molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD), research in III-V compound semiconductor photonic devices has flourished. Advances in fabrication processes have allowed the realization of high-performance quantum well lasers which emit over a wide spectral range and operate with low threshold currents. As a result, semiconductor lasers are presently employed in a wide variety of applications, including fiber-optic telecommunications, optical spectroscopy, solid-state laser pumping, and photonic integrated circuits. The work in this dissertation addresses three photonic device structures which are currently receiving a great deal of attention in the research community: integrable quantum well laser devices, distributed feedback (DFB) laser devices, and quantum wire arrays. For the realization of the integrable and integrated photonic devices described-in Chapter 2, a three-step selective-area growth technique was utilized. The selective epitaxy process was used to produce discrete buried-heterostructure Fabry Perot lasers with threshold currents as low as 2.6 mA. Based on this process, broad- spectrum edge-emitting superluminescent diodes are demonstrated which display spectral widths of over 80 nm. In addition, the monolithic integration of a multiwavelength emitter is demonstrated in which two distinct laser sources are coupled into a single output waveguide. The dissertation also describes the development of a single-growth-step ridge waveguide DFB laser. The DFB laser utilizes an asymmetric cladding waveguide structure to enhance the interaction of the optical mode with the titanium surface metal to promote single frequency emission via gain coupling. These lasers exhibit low threshold currents (11 mA), high side mode suppression ratios (50 dB), and narrow linewidths (45 kHz). In light of the substantial performance advantages of quantum well lasers relative to double heterostructure lasers, extensive efforts have been directed toward producing quantum wire systems. In view of this, the final subject of this dissertation details the fabrication and characterization of quantum wire arrays by selective-area MOCVD. The method employs a silicon dioxide grating mask with sub-micron oxide dimensions to achieve selective deposition of high-quality buried layers in the open areas of the patterned substrate. This allows the fabrication of embedded nanostructures in a single growth step, and the crystallographic nature of the growth allows for control of their lateral size. Using this process, the growth of strained InGaAs wires with a lateral dimension of less than 50 nm are obtained. Subsequent characterization by photoluminescence, scanning electron microscopy and transmission electron microscopy is also presented.

Novel Technique and Technologies for Active Optical Remote Sensing of Greenhouse Gases

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Refaat, Tamer F.; Petros, Mulugeta

2017-01-01

The societal benefits of understanding climate change through identification of global carbon dioxide sources and sinks led to the desired NASA's active sensing of carbon dioxide emissions over nights, days, and seasons (ASCENDS) space-based missions of global carbon dioxide measurements. For more than 15 years, NASA Langley Research Center (LaRC) have developed several carbon dioxide active remote sensors using the differential absorption lidar (DIAL) technique operating at the two-micron wavelength. Currently, an airborne two-micron triple-pulse integrated path differential absorption (IPDA) lidar is under development. This IPDA lidar measures carbon dioxide as well as water vapor, the dominant interfering molecule on carbon dioxide remote sensing. Advancement of this triple-pulse IPDA lidar development is presented.

Fractional ablative carbon dioxide laser resurfacing for skin rejuvenation and acne scars in Asians.

PubMed

Chan, Nicola P Y; Ho, Stephanie G Y; Yeung, Chi K; Shek, Samantha Y N; Chan, Henry H

2010-11-01

Ablative fractional resurfacing (AFR) is a new modality for photorejuvenation and acne scars which combines carbon dioxide (CO₂) laser ablation with fractional photothermolysis. The objective is to evaluate the efficacy and side effects of a new fractional CO₂ ablative device (Fraxel Re:pair) for skin rejuvenation and acne scars in Asians. Nine patients underwent one full-face treatment. The energy levels ranged from 30-70 mJ with coverage between 30% and 45%. Improvement in skin texture, laxity, wrinkles, enlarged pores, overall pigmentation irregularity, and adverse effects were assessed up to 6 months post-treatment. Standardized photographs using the Canfield Visia CR system® were assessed by two independent observers. Subjective improvement was assessed by patient questionnaires. Nine Chinese patients (skin types III and IV, mean age 44.8) were included. Statistically significant improvements were seen for skin texture, skin laxity, wrinkles, enlarged pores, and acne scars. The post-inflammatory hyperpigmentation rate was 55.5% and 11.1% at 1 and 6 months post-treatment, respectively. Eighty-six percent of patients were overall satisfied to very satisfied with the treatment. Ablative fractional CO₂ laser resurfacing was overall safe and effective for skin rejuvenation and acne scars in Asians. However, in view of the high post-inflammatory rate and the statistically significant but only mild to moderate improvement after a single treatment as observed in this study, there is a need to review the current role of fractional ablative CO₂ laser treatment as compared to fractional non-ablative for skin rejuvenation and acne scar treatment in Asians. © 2010 Wiley-Liss, Inc.

Electrochemical carbon dioxide concentrator: Math model

NASA Technical Reports Server (NTRS)

Marshall, R. D.; Schubert, F. H.; Carlson, J. N.

1973-01-01

A steady state computer simulation model of an Electrochemical Depolarized Carbon Dioxide Concentrator (EDC) has been developed. The mathematical model combines EDC heat and mass balance equations with empirical correlations derived from experimental data to describe EDC performance as a function of the operating parameters involved. The model is capable of accurately predicting performance over EDC operating ranges. Model simulation results agree with the experimental data obtained over the prediction range.

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.

Correlation of plume dynamics and oxygen pressure with VO2 stoichiometry during pulsed laser deposition

NASA Astrophysics Data System (ADS)

Lafane, S.; Kerdja, T.; Abdelli-Messaci, S.; Khereddine, Y.; Kechouane, M.; Nemraoui, O.

2013-07-01

Vanadium dioxide thin films have been deposited on Corning glass substrates by a KrF laser ablation of V2O5 target at the laser fluence of 2 J cm-2. The substrate temperature and the target-substrate distance were set to 500 ∘C and 4 cm, respectively. X-ray diffraction analysis showed that pure VO2 is only obtained at an oxygen pressure range of 4×10-3-2×10-2 mbar. A higher optical switching contrast was obtained for the VO2 films deposited at 4×10-3-10-2 mbar. The films properties were correlated to the plume-oxygen gas interaction monitored by fast imaging of the plume.

Fractional laser microablation of skin aimed at enhancing its permeability for nanoparticles

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

Genina, Elina A; Dolotov, L E; Bashkatov, A N

2011-05-31

A new method for delivering nanoparticles into the skin using the fractional laser microablation of its surface and the ultrasonic treatment is proposed. As a result of in vitro and in vivo studies, it is shown that the 290-nm laser pulses with the energy from 0.5 to 3.0 J provide the penetration of nanoparticles of titanium dioxide with the diameter {approx}100 nm from the skin surface to the depth, varying from 150 to 400 {mu}m. Histological testing of the skin areas, subjected to the treatment, shows that the particles stay in the dermis at the depth up to 400 {mu}mmore » no less than for three weeks. (optical technologies in biophysics and medicine)« less

Remote Operations of Laser Guide Star Systems: Gemini Observatory.

NASA Astrophysics Data System (ADS)

Oram, Richard J.; Fesquet, Vincent; Wyman, Robert; D'Orgeville, Celine

2011-03-01

The Gemini North telescope, equipped with a 14W laser, has been providing Laser Guide Star Adaptive Optics (LGS AO) regular science queue observations for worldwide astronomers since February 2007. The new 55W laser system for MCAO was installed on the Gemini South telescope in May 2010. In this paper, we comment on how Gemini Observatory developed regular remote operation of the Laser Guide Star Facility and high-power solid-state laser as routine normal operations. Fully remote operation of the LGSF from the Hilo base facility HBF was initially trialed and then optimized and became the standard operating procedure (SOP) for LGS operation in December 2008. From an engineering perspective remote operation demands stable, well characterized and base-lined equipment sets. In the effort to produce consistent, stable and controlled laser parameters (power, wavelength and beam quality) we completed a failure mode effect analysis of the laser system and sub systems that initiated a campaign of hardware upgrades and procedural improvements to the routine maintenance operations. Finally, we provide an overview of normal operation procedures during LGS runs and present a snapshot of data accumulated over several years that describes the overall LGS AO observing efficiency at the Gemini North telescope.

Catalytic Converters Maintain Air Quality in Mines

NASA Technical Reports Server (NTRS)

2014-01-01

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