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Sample records for laser vaporization methods

  1. Self-tuning method for monitoring the density of a gas vapor component using a tunable laser

    DOEpatents

    Hagans, Karla; Berzins, Leon; Galkowski, Joseph; Seng, Rita

    1996-01-01

    The present invention relates to a vapor density monitor and laser atomic absorption spectroscopy method for highly accurate, continuous monitoring of vapor densities, composition, flow velocity, internal and kinetic temperatures and constituent distributions. The vapor density monitor employs a diode laser, preferably of an external cavity design. By using a diode laser, the vapor density monitor is significantly less expensive and more reliable than prior art vapor density monitoring devices. In addition, the compact size of diode lasers enables the vapor density monitor to be portable. According to the method of the present invention, the density of a component of a gas vapor is calculated by tuning the diode laser to a frequency at which the amount of light absorbed by the component is at a minimum or a maximum within about 50 MHz of that frequency. Laser light from the diode laser is then transmitted at the determined frequency across a predetermined pathlength of the gas vapor. By comparing the amount of light transmitted by the diode laser to the amount of light transmitted after the laser light passes through the gas vapor, the density of the component can be determined using Beer's law.

  2. Self-tuning method for monitoring the density of a gas vapor component using a tunable laser

    DOEpatents

    Hagans, K.; Berzins, L.; Galkowski, J.; Seng, R.

    1996-08-27

    The present invention relates to a vapor density monitor and laser atomic absorption spectroscopy method for highly accurate, continuous monitoring of vapor densities, composition, flow velocity, internal and kinetic temperatures and constituent distributions. The vapor density monitor employs a diode laser, preferably of an external cavity design. By using a diode laser, the vapor density monitor is significantly less expensive and more reliable than prior art vapor density monitoring devices. In addition, the compact size of diode lasers enables the vapor density monitor to be portable. According to the method of the present invention, the density of a component of a gas vapor is calculated by tuning the diode laser to a frequency at which the amount of light absorbed by the component is at a minimum or a maximum within about 50 MHz of that frequency. Laser light from the diode laser is then transmitted at the determined frequency across a predetermined pathlength of the gas vapor. By comparing the amount of light transmitted by the diode laser to the amount of light transmitted after the laser light passes through the gas vapor, the density of the component can be determined using Beer`s law. 6 figs.

  3. Production of pulsed atomic oxygen beams via laser vaporization methods

    NASA Technical Reports Server (NTRS)

    Brinza, David E.; Coulter, Daniel R.; Liang, Ranty H.; Gupta, Amitava

    1986-01-01

    The generation of energetic pulsed atomic oxygen beams by laser-driven evaporation of cryogenically frozen ozone/oxygen films and thin indium-tin oxide (ITO) films is reported. Mass spectroscopy is used in the mass and energy characterization of beams from the ozone/oxygen films, and a peak flux of 3 x 10 to the 20th/sq m per sec at 10 eV is found. Analysis of the time-of-flight data suggests that several processes contribute to the formation of the oxygen beam. Results show the absence of metastable states such as the 2p(3)3s(1)(5S) level of atomic oxygen blown-off from the ITO films. The present process has application to the study of the oxygen degradation problem of LEO materials.

  4. Production of pulsed atomic oxygen beams via laser vaporization methods

    NASA Technical Reports Server (NTRS)

    Brinza, David E.; Coulter, Daniel R.; Liang, Ranty H.; Gupta, Amitava

    1987-01-01

    Energetic pulsed atomic oxygen beams were generated by laser-driven evaporation of cryogenically frozen ozone/oxygen films and thin films of indium-tin oxide (ITO). Mass and energy characterization of beams from the ozone/oxygen films were carried out by mass spectrometry. The peak flux, found to occur at 10 eV, is estimated from this data to be 3 x 10(20) m(-2) s(-1). Analysis of the time-of-flight data indicates a number of processes contribute to the formation of the atomic oxygen beam. The absence of metastable states such as the 2p(3) 3s(1) (5S) level of atomic oxygen blown off from ITO films is supported by the failure to observe emission at 777.3 nm from the 2p(3) 3p(1) (5P sub J) levels. Reactive scattering experiments with polymer film targets for atomic oxygen bombardment are planned using a universal crossed molecular beam apparatus.

  5. Multiwavelength Strontium Vapor Lasers

    NASA Astrophysics Data System (ADS)

    Soldatov, A. N.; Yudin, N. A.

    2016-08-01

    Based on an analysis of experimental and theoretical works, modern notion on conditions of forming of population density inversion on self-terminating IR transitions of alkali-earth metals is given. It is demonstrated that there is a significant difference in the inversion formation in lasers on self-terminating transitions in the visible and near-IR ranges and lasers on self-terminating transitions of alkali-earth metals lasing IR lines in the mid-IR range. It is shown that in the discharge circuit of lasers on self-terminating metal atom transitions (LSMT) there are processes strengthening the influence of the known mechanism limiting the frequency and energy characteristics (FEC) of radiation caused by the presence of prepulse electron concentration. The mechanism of influence of these processes on FEC of the LSMT and technical methods of their neutralization are considered. The possibility of obtaining average lasing power of ~200 W from one liter volume of the active medium of the strontium vapor laser is demonstrated under conditions of neutralization of these processes.

  6. Iron bromide vapor laser

    NASA Astrophysics Data System (ADS)

    Sukhanov, V. B.; Shiyanov, D. V.; Trigub, M. V.; Dimaki, V. A.; Evtushenko, G. S.

    2016-03-01

    We have studied the characteristics of a pulsed gas-discharge laser on iron bromide vapor generating radiation with a wavelength of 452.9 nm at a pulse repetition frequency (PRF) of 5-30 kHz. The maximum output power amounted to 10 mW at a PRF within 5-15 kHz for a voltage of 20-25 kV applied to electrodes of the discharge tube. Addition of HBr to the medium produced leveling of the radial profile of emission. Initial weak lasing at a wavelength of 868.9 nm was observed for the first time, which ceased with buildup of the main 452.9-nm line.

  7. Diode pumped alkali vapor fiber laser

    DOEpatents

    Payne, Stephen A.; Beach, Raymond J.; Dawson, Jay W.; Krupke, William F.

    2006-07-26

    A method and apparatus is provided for producing near-diffraction-limited laser light, or amplifying near-diffraction-limited light, in diode pumped alkali vapor photonic-band-gap fiber lasers or amplifiers. Laser light is both substantially generated and propagated in an alkali gas instead of a solid, allowing the nonlinear and damage limitations of conventional solid core fibers to be circumvented. Alkali vapor is introduced into the center hole of a photonic-band-gap fiber, which can then be pumped with light from a pump laser and operated as an oscillator with a seed beam, or can be configured as an amplifier.

  8. Diode pumped alkali vapor fiber laser

    DOEpatents

    Payne, Stephen A.; Beach, Raymond J.; Dawson, Jay W.; Krupke, William F.

    2007-10-23

    A method and apparatus is provided for producing near-diffraction-limited laser light, or amplifying near-diffraction-limited light, in diode pumped alkali vapor photonic-band-gap fiber lasers or amplifiers. Laser light is both substantially generated and propagated in an alkali gas instead of a solid, allowing the nonlinear and damage limitations of conventional solid core fibers to be circumvented. Alkali vapor is introduced into the center hole of a photonic-band-gap fiber, which can then be pumped with light from a pump laser and operated as an oscillator with a seed beam, or can be configured as an amplifier.

  9. Atomic vapor laser isotope separation process

    DOEpatents

    Wyeth, R.W.; Paisner, J.A.; Story, T.

    1990-08-21

    A laser spectroscopy system is utilized in an atomic vapor laser isotope separation process. The system determines spectral components of an atomic vapor utilizing a laser heterodyne technique. 23 figs.

  10. Comparison of cervical dysplasia treatment with leep-loop method and CO2 laser vaporization

    NASA Astrophysics Data System (ADS)

    Wozniak, Jakub; Rzymski, Pawel; Opala, Tomasz; Wilczak, Maciej; Sajdak, Stefan

    2003-10-01

    There are several methods of treating cervical dysplasia, including surgical and electric conisation, laservaporisation. The aim of our study was to evaluate leep-loop method and laservaporisation wtih CO2 laser. Material consisted of 49 women, 28 underwent leep-loop conisation and 21 lavervaporisation. The effectiveness of laser treatment was 90,4% and with leep-loop 96,4%, but the difference was not statistically significant. Mean time of wound healing and frequency of pain was shorter after laser treatment, but the differences were not statistically significant. Conclusions: Effect treatment with both methods is comparable.

  11. Alkali-vapor lasers

    NASA Astrophysics Data System (ADS)

    Zweiback, J.; Komashko, A.; Krupke, W. F.

    2010-02-01

    We report on the results from several of our alkali laser systems. We show highly efficient performance from an alexandrite-pumped rubidium laser. Using a laser diode stack as a pump source, we demonstrate up to 145 W of average power from a CW system. We present a design for a transversely pumped demonstration system that will show all of the required laser physics for a high power system.

  12. Vapor spill monitoring method

    DOEpatents

    Bianchini, Gregory M.; McRae, Thomas G.

    1985-01-01

    Method for continuous sampling of liquified natural gas effluent from a spill pipe, vaporizing the cold liquified natural gas, and feeding the vaporized gas into an infrared detector to measure the gas composition. The apparatus utilizes a probe having an inner channel for receiving samples of liquified natural gas and a surrounding water jacket through which warm water is flowed to flash vaporize the liquified natural gas.

  13. Atomic vapor laser isotope separation

    SciTech Connect

    Stern, R.C.; Paisner, J.A.

    1985-11-08

    Atomic vapor laser isotope separation (AVLIS) is a general and powerful technique. A major present application to the enrichment of uranium for light-water power reactor fuel has been under development for over 10 years. In June 1985 the Department of Energy announced the selection of AVLIS as the technology to meet the nation's future need for the internationally competitive production of uranium separative work. The economic basis for this decision is considered, with an indicated of the constraints placed on the process figures of merit and the process laser system. We then trace an atom through a generic AVLIS separator and give examples of the physical steps encountered, the models used to describe the process physics, the fundamental parameters involved, and the role of diagnostic laser measurements.

  14. Copper vapor laser modular packaging assembly

    DOEpatents

    Alger, T.W.; Ault, E.R.; Moses, E.I.

    1992-12-01

    A modularized packaging arrangement for one or more copper vapor lasers and associated equipment is disclosed herein. This arrangement includes a single housing which contains the laser or lasers and all their associated equipment except power, water and neon, and means for bringing power, water, and neon which are necessary to the operation of the lasers into the container for use by the laser or lasers and their associated equipment. 2 figs.

  15. Copper vapor laser modular packaging assembly

    DOEpatents

    Alger, Terry W.; Ault, Earl R.; Moses, Edward I.

    1992-01-01

    A modularized packaging arrangement for one or more copper vapor lasers and associated equipment is disclosed herein. This arrangement includes a single housing which contains the laser or lasers and all their associated equipment except power, water and neon, and means for bringing power, water, and neon which are necessary to the operation of the lasers into the container for use by the laser or lasers and their associated equipment.

  16. Copper vapor laser acoustic thermometry system

    DOEpatents

    Galkowski, Joseph J.

    1987-01-01

    A copper vapor laser (CVL) acoustic thermometry system is disclosed. The invention couples an acoustic pulse a predetermined distance into a laser tube by means of a transducer and an alumina rod such that an echo pulse is returned along the alumina rod to the point of entry. The time differential between the point of entry of the acoustic pulse into the laser tube and the exit of the echo pulse is related to the temperature at the predetermined distance within the laser tube. This information is processed and can provide an accurate indication of the average temperature within the laser tube.

  17. Physico-technical background of metal vapor laser systems and their application in oncology

    NASA Astrophysics Data System (ADS)

    Armichev, A. V.; Ivanov, Andrei V.; Kazaryan, Mishik A.

    1996-01-01

    Some results of the copper and gold vapor lasers and of helium-cadmium lasers used in medical practice are presented. The most in medical use copper vapor laser is commonly applied for low-intensity laser therapy and endoscopic surgery. A universal capability of dye lasers oscillating in 600 - 670 red region for excitation of the preparates used in photodynamic therapy is demonstrated. The copper vapor lasers are shown also to effectively coagulate pre- tumor neoplasms. A new method of laser beams shaping fitted to tumor configuration basing on quantum optical systems including image brightness amplifiers is described. Variability of the irradiating beam contrast is displayed, including the contrast inversion. Possibilities of the copper vapor lasers use for tumors drugless phototherapy and the two-step and two-stage methods of the photodynamic therapy are discussed. Some Russian medical systems based on the copper vapor lasers and dye lasers pumped by them are specified in parameters.

  18. Metal vapor lasers with increased reliability

    NASA Astrophysics Data System (ADS)

    Soldatov, A. N.; Sabotinov, N. V.; Polunin, Yu. P.; Shumeiko, A. S.; Kostadinov, I. K.; Vasilieva, A. V.; Reimer, I. V.

    2015-12-01

    Results of investigation and development of an excitation pulse generator with magnetic pulse compression by saturation chokes for pumping of active media of CuBr, Sr, and Ca vapor lasers are presented. A high-power IGBT transistor is used as a commutator. The generator can operate at excitation pulse repetition frequencies up to 20 kHz. The total average power for all laser lines of the CuBr laser pumped by this generator is ~6.0 W; it is ~1.3-1.7 W for the Sr and Ca lasers.

  19. Alkali metal vapors - Laser spectroscopy and applications

    NASA Technical Reports Server (NTRS)

    Stwalley, W. C.; Koch, M. E.

    1980-01-01

    The paper examines the rapidly expanding use of lasers for spectroscopic studies of alkali metal vapors. Since the alkali metals (lithium, sodium, potassium, rubidium and cesium) are theoretically simple ('visible hydrogen'), readily ionized, and strongly interacting with laser light, they represent ideal systems for quantitative understanding of microscopic interconversion mechanisms between photon (e.g., solar or laser), chemical, electrical and thermal energy. The possible implications of such understanding for a wide variety of practical applications (sodium lamps, thermionic converters, magnetohydrodynamic devices, new lasers, 'lithium waterfall' inertial confinement fusion reactors, etc.) are also discussed.

  20. New Medical Applications Of Metal Vapor Lasers

    NASA Astrophysics Data System (ADS)

    Anderson, Robert S.; McIntosh, Alexander I.

    1989-06-01

    The first medical application for metal vapor lasers has been granted marketing approval by the FDA. This represents a major milestone for this technology. Metalaser Technologies recently received this approval for its Vasculase unit in the treatment of vascular lesions such as port wine stains, facial telangiectasia and strawberry hemangiomas.

  1. Copper vapor laser development for SILVA

    NASA Astrophysics Data System (ADS)

    Bettinger, Antoine; Neu, M.; Maury, J.; Chatelet, Jacques A.

    1993-05-01

    The recent developments of the components for high power Copper Vapor Laser (CVL) have been oriented towards four main goals: high quality laser beam, mainly for the CVL oscillators, increase of the extracted energy out of the amplifying stage, fully integrated and monolithic design for oscillator and amplifier, and extended lifetime and high reliability. A first step of this work, which is done under contract with CILAS (Compagnie Industrielle des Lasers) led to an injection seeded oscillator and a 100 Watt amplifier; the present step concerns development of a 400 Watts class amplifier.

  2. Monitoring PVD metal vapors using laser absorption spectroscopy

    SciTech Connect

    Braun, D.G.; Anklam, T.M.; Berzins, L.V.; Hagans, K.G.

    1994-04-01

    Laser absorption spectroscopy (LAS) has been used by the Atomic Vapor Laser Isotope Separation (AVLIS) program for over 10 years to monitor the co-vaporization of uranium and iron in its separators. During that time, LAS has proven to be an accurate and reliable method to monitor both the density and composition of the vapor. It has distinct advantages over other rate monitors, in that it is completely non-obtrusive to the vaporization process and its accuracy is unaffected by the duration of the run. Additionally, the LAS diagnostic has been incorporated into a very successful process control system. LAS requires only a line of sight through the vacuum chamber, as all hardware is external to the vessel. The laser is swept in frequency through an absorption line of interest. In the process a baseline is established, and the line integrated density is determined from the absorption profile. The measurement requires no hardware calibration. Through a proper choice of the atomic transition, a wide range of elements and densities have been monitored (e.g. nickel, iron, cerium and gadolinium). A great deal of information about the vapor plume can be obtained from the measured absorption profiles. By monitoring different species at the same location, the composition of the vapor is measured in real time. By measuring the same density at different locations, the spatial profile of the vapor plume is determined. The shape of the absorption profile is used to obtain the flow speed of the vapor. Finally, all of the above information is used evaluate the total vaporization rate.

  3. Transverse-pumped Cs vapor laser

    NASA Astrophysics Data System (ADS)

    Zhdanov, B. V.; Shaffer, M. K.; Sell, J.; Knize, R. J.

    2009-02-01

    Scaling of alkali lasers to higher powers requires combining beams of multiple diode laser pump sources. For longitudinal pumping this can be very complicated if more than four beams are to be combined. In this paper we report a first demonstration of a transversely pumped Cs laser with fifteen laser diode arrays. The LDA pump beams were individually collimated with a beam size of about 1 x 4 cm as measured at a 1 m distance from the diodes. All these beams were incident on a cylindrical lens to be focused and coupled through the side slit of a hollow, cylindrical diffuse reflector which contained the Cs vapor cell. We measured the output power and efficiency of the Cs laser for pump powers up to 200 W at different cell temperatures. Although the values of output power and slope efficiency obtained for this laser system were less than those for a longitudinally pumped alkali laser, these recent results can be significantly improved by using a more optimal laser cavity design. The demonstrated operation of Cs laser with transverse pumping opens new possibilities in power scaling of alkali lasers.

  4. Laser Velocimetry of Chemical Vapor Deposition Flows

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Laser velocimetry (LV) is being used to measure the gas flows in chemical vapor deposition (CVD) reactors. These gas flow measurements can be used to improve industrial processes in semiconductor and optical layer deposition and to validate numerical models. Visible in the center of the picture is the graphite susceptor glowing orange-hot at 600 degrees C. It is inductively heated via the copper cool surrounding the glass reactor.

  5. Water vapor-nitrogen absorption at CO2 laser frequencies

    NASA Technical Reports Server (NTRS)

    Peterson, J. C.; Thomas, M. E.; Nordstrom, R. J.; Damon, E. K.; Long, R. K.

    1979-01-01

    The paper reports the results of a series of pressure-broadened water vapor absorption measurements at 27 CO2 laser frequencies between 935 and 1082 kaysers. Both multiple traversal cell and optoacoustic (spectrophone) techniques were utilized together with an electronically stabilized CW CO2 laser. Comparison of the results obtained by these two methods shows remarkable agreement, indicating a precision which has not been previously achieved in pressure-broadened studies of water vapor. The data of 10.59 microns substantiate the existence of the large (greater than 200) self-broadening coefficients determined in an earlier study by McCoy. In this work, the case of water vapor in N2 at a total pressure of 1 atm has been treated.

  6. Ambient Femtosecond Laser Vaporization and Nanosecond Laser Desorption Electrospray Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Flanigan, Paul; Levis, Robert

    2014-06-01

    Recent investigations of ambient laser-based transfer of molecules into the gas phase for subsequent mass spectral analysis have undergone a renaissance resulting from the separation of vaporization and ionization events. Here, we seek to provide a snapshot of recent femtosecond (fs) duration laser vaporization and nanosecond (ns) duration laser desorption electrospray ionization mass spectrometry experiments. The former employs pulse durations of <100 fs to enable matrix-free laser vaporization with little or no fragmentation. When coupled to electrospray ionization, femtosecond laser vaporization provides a universal, rapid mass spectral analysis method requiring no sample workup. Remarkably, laser pulses with intensities exceeding 1013 W cm-2 desorb intact macromolecules, such as proteins, and even preserve the condensed phase of folded or unfolded protein structures according to the mass spectral charge state distribution, as demonstrated for cytochrome c and lysozyme. Because of the ability to vaporize and ionize multiple components from complex mixtures for subsequent analysis, near perfect classification of explosive formulations, plant tissue phenotypes, and even the identity of the manufacturer of smokeless powders can be determined by multivariate statistics. We also review the more mature field of nanosecond laser desorption for ambient mass spectrometry, covering the wide range of systems analyzed, the need for resonant absorption, and the spatial imaging of complex systems like tissue samples.

  7. Ambient femtosecond laser vaporization and nanosecond laser desorption electrospray ionization mass spectrometry.

    PubMed

    Flanigan, Paul; Levis, Robert

    2014-01-01

    Recent investigations of ambient laser-based transfer of molecules into the gas phase for subsequent mass spectral analysis have undergone a renaissance resulting from the separation of vaporization and ionization events. Here, we seek to provide a snapshot of recent femtosecond (fs) duration laser vaporization and nanosecond (ns) duration laser desorption electrospray ionization mass spectrometry experiments. The former employs pulse durations of <100 fs to enable matrix-free laser vaporization with little or no fragmentation. When coupled to electrospray ionization, femtosecond laser vaporization provides a universal, rapid mass spectral analysis method requiring no sample workup. Remarkably, laser pulses with intensities exceeding 10(13) W cm(-2) desorb intact macromolecules, such as proteins, and even preserve the condensed phase of folded or unfolded protein structures according to the mass spectral charge state distribution, as demonstrated for cytochrome c and lysozyme. Because of the ability to vaporize and ionize multiple components from complex mixtures for subsequent analysis, near perfect classification of explosive formulations, plant tissue phenotypes, and even the identity of the manufacturer of smokeless powders can be determined by multivariate statistics. We also review the more mature field of nanosecond laser desorption for ambient mass spectrometry, covering the wide range of systems analyzed, the need for resonant absorption, and the spatial imaging of complex systems like tissue samples.

  8. Injection locked oscillator system for pulsed metal vapor lasers

    DOEpatents

    Warner, Bruce E.; Ault, Earl R.

    1988-01-01

    An injection locked oscillator system for pulsed metal vapor lasers is disclosed. The invention includes the combination of a seeding oscillator with an injection locked oscillator (ILO) for improving the quality, particularly the intensity, of an output laser beam pulse. The present invention includes means for matching the first seeder laser pulses from the seeding oscillator to second laser pulses of a metal vapor laser to improve the quality, and particularly the intensity, of the output laser beam pulse.

  9. Metal vapor laser including hot electrodes and integral wick

    DOEpatents

    Ault, Earl R.; Alger, Terry W.

    1995-01-01

    A metal vapor laser, specifically one utilizing copper vapor, is disclosed herein. This laser utilizes a plasma tube assembly including a thermally insulated plasma tube containing a specific metal, e.g., copper, and a buffer gas therein. The laser also utilizes means including hot electrodes located at opposite ends of the plasma tube for electrically exciting the metal vapor and heating its interior to a sufficiently high temperature to cause the metal contained therein to vaporize and for subjecting the vapor to an electrical discharge excitation in order to lase. The laser also utilizes external wicking arrangements, that is, wicking arrangements located outside the plasma tube.

  10. Metal vapor laser including hot electrodes and integral wick

    DOEpatents

    Ault, E.R.; Alger, T.W.

    1995-03-07

    A metal vapor laser, specifically one utilizing copper vapor, is disclosed herein. This laser utilizes a plasma tube assembly including a thermally insulated plasma tube containing a specific metal, e.g., copper, and a buffer gas therein. The laser also utilizes means including hot electrodes located at opposite ends of the plasma tube for electrically exciting the metal vapor and heating its interior to a sufficiently high temperature to cause the metal contained therein to vaporize and for subjecting the vapor to an electrical discharge excitation in order to lase. The laser also utilizes external wicking arrangements, that is, wicking arrangements located outside the plasma tube. 5 figs.

  11. Tunable lasers for water vapor measurements and other lidar applications

    NASA Technical Reports Server (NTRS)

    Gammon, R. W.; Mcilrath, T. J.; Wilkerson, T. D.

    1977-01-01

    A tunable dye laser suitable for differential absorption (DIAL) measurements of water vapor in the troposphere was constructed. A multi-pass absorption cell for calibration was also constructed for use in atmospheric DIAL measurements of water vapor.

  12. Fabrication and laser performance of Yb3+/Al3+ co-doped photonic crystal fiber synthesized by plasma nonchemical vapor deposition method

    NASA Astrophysics Data System (ADS)

    Xia, Changming; Zhou, Guiyao; Liu, Jiantao; Wang, Chao; Han, Ying; Zhang, Wei; Yuan, Jinhui

    2015-10-01

    In this paper, the bulk Yb3+/Al3+ co-doped silica glass with 1.3 Yb2O3-2.5Al2O3-96.2SiO2 (wt%) are synthesized by plasma nonchemical vapor deposition method combining solution doping technology, where the inductively coupled plasma is used as the heat source. The influence of different O2/N2 ratios on the fluorescence properties of Yb3+/Al3+ co-doped silica glass are investigated. The large mode area photonic crystal fiber (PCF) is fabricated by using the bulk Yb3+/Al3+ co-doped silica glass as fiber core. The laser performance of Yb3+/Al3+ co-doped photonic crystal fiber is studied.

  13. Quasi-dynamical analysis and real-time tissue temperature monitoring during laser vaporization

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Ray, Aditi; Jebens, Dave; Chia, Ray; Hasenberg, Tom

    2014-03-01

    Vaporization and coagulation are two fundamental processes that can be performed during laser-tissue ablation. We demonstrated a method allowing quasi-dynamically observing of the cross-sectional images of tissue response during ablation. The results showed that coagulation depth is relatively constant during vaporization, which supports the excellent hemostasis of green laser benign prostate hyperplasia (BPH) treatment. We also verified a new technology for real-time, in situ tissue temperature monitoring, which may be promising for in vivo tissue vaporization degree feedback during laser ablation to improve the vaporization efficiency and avoid complications.

  14. Study of the Characteristics of a Laser Based on the Cr2+-Ion Doped ZnS Polycrystal Obtained by the Method of Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Egorov, A. S.; Savikin, A. P.; Eremeikin, O. N.; Ikonnikov, V. B.; Gavrishchuk, E. M.; Savin, D. V.

    2016-01-01

    We study the lasing characteristics of the Cr2+:ZnS-crystal laser pumped by the pulsed-periodic Tm3+:YLF laser, as well as the lasing polarization properties. The Cr2+:ZnS sample was obtained by chemical vapor deposition of zinc sulfide doped by the chrome ions in the hightemperature isostatic processing. Total efficiency of the pump-power conversion to lasing power at a level of 33% was reached, which corresponds to a laser differential efficiency of about 55% in terms of the absorbed power.

  15. Heat-Pipe Bismuth Laser; Examination of Laser Action at 4722A in Bismuth Vapor

    DTIC Science & Technology

    1976-11-01

    Terminating Laser Transitions in Calcium and Strontium. " IEEE J. Quantum Electron. QE-4, 474 (1968). 7. P.Cahuzac, "Raies Laser Infrarouges dans les Vapeurs... Spectroscopy 19. 282(1065). 13. P.A. Rice and D. V. Ragone, "Simultaneous Determination of f Values and Vapor Pressures from Optical Absorption Measurements...approaching 10%6. Beam foil spectroscopy can be included with these more accurate methods if one can be certain that there is no unrecognized

  16. Application of laser Doppler velocimeter to chemical vapor laser system

    NASA Technical Reports Server (NTRS)

    Gartrell, Luther R.; Hunter, William W., Jr.; Lee, Ja H.; Fletcher, Mark T.; Tabibi, Bagher M.

    1993-01-01

    A laser Doppler velocimeter (LDV) system was used to measure iodide vapor flow fields inside two different-sized tubes. Typical velocity profiles across the laser tubes were obtained with an estimated +/-1 percent bias and +/-0.3 to 0.5 percent random uncertainty in the mean values and +/-2.5 percent random uncertainty in the turbulence-intensity values. Centerline velocities and turbulence intensities for various longitudinal locations ranged from 13 to 17.5 m/sec and 6 to 20 percent, respectively. In view of these findings, the effects of turbulence should be considered for flow field modeling. The LDV system provided calibration data for pressure and mass flow systems used routinely to monitor the research laser gas flow velocity.

  17. Vapor generation methods for explosives detection research

    SciTech Connect

    Grate, Jay W.; Ewing, Robert G.; Atkinson, David A.

    2012-12-01

    The generation of calibrated vapor samples of explosives compounds remains a challenge due to the low vapor pressures of the explosives, adsorption of explosives on container and tubing walls, and the requirement to manage (typically) multiple temperature zones as the vapor is generated, diluted, and delivered. Methods that have been described to generate vapors can be classified as continuous or pulsed flow vapor generators. Vapor sources for continuous flow generators are typically explosives compounds supported on a solid support, or compounds contained in a permeation or diffusion device. Sources are held at elevated isothermal temperatures. Similar sources can be used for pulsed vapor generators; however, pulsed systems may also use injection of solutions onto heated surfaces with generation of both solvent and explosives vapors, transient peaks from a gas chromatograph, or vapors generated by s programmed thermal desorption. This article reviews vapor generator approaches with emphasis on the method of generating the vapors and on practical aspects of vapor dilution and handling. In addition, a gas chromatographic system with two ovens that is configurable with up to four heating ropes is proposed that could serve as a single integrated platform for explosives vapor generation and device testing. Issues related to standards, calibration, and safety are also discussed.

  18. Method and apparatus for vapor detection

    NASA Technical Reports Server (NTRS)

    Lerner, Melvin (Inventor); Hood, Lyal V. (Inventor); Rommel, Marjorie A. (Inventor); Pettitt, Bruce C. (Inventor); Erikson, Charles M. (Inventor)

    1980-01-01

    The method disclosed herein may be practiced by passing the vapors to be sampled along a path with halogen vapor, preferably chlorine vapor, heating the mixed vapors to halogenate those of the sampled vapors subject to halogenation, removing unreacted halogen vapor, and then sensing the vapors for organic halogenated compounds. The apparatus disclosed herein comprises means for flowing the vapors, both sample and halogen vapors, into a common path, means for heating the mixed vapors to effect the halogenation reaction, means for removing unreacted halogen vapor, and a sensing device for sensing halogenated compounds. By such a method and means, the vapors of low molecular weight hydrocarbons, ketones and alcohols, when present, such as methane, ethane, acetone, ethanol, and the like are converted, at least in part, to halogenated compounds, then the excess halogen removed or trapped, and the resultant vapors of the halogenated compounds sensed or detected. The system is highly sensitive. For example, acetone in a concentration of 30 parts per billion (volume) is readily detected.

  19. The one year outcome after KTP laser vaporization of the prostate according to the calculated vaporized volume.

    PubMed

    Ku, Ja Hyeon; Cho, Jeong Yeon; Cho, Sung Yong; Kim, Soo Woong; Paick, Jae-Seung

    2009-12-01

    The aim of this study was to develop a new simple method for measuring the vaporized volume and to evaluate the outcome of high-power potassium-titanyl-phosphate (KTP) photoselective laser vaporization. A total of 65 patients, with a mean age of 67.7 yr (range 53 to 85), were included in the primary analysis. The vaporized volume was calculated as the pre-operative volume minus the immediate post-operative volume plus the volume of the defect. For all patients, the subjective and objective parameters improved significantly after surgery. Six and 12 months after surgery, the group with a smaller vaporized volume (<15 g) had a lower reduction of the mean International Prostate Symptom Score (P=0.006 and P=0.004) and quality of life index (P=0.006 and P=0.004) when compared to the group with a greater vaporized volume (>or=15 g). There were no differences in the change of the maximum flow rate and post-void residual based on the vaporized volume. Our findings suggest that the subjective improvement, after a high-power KTP laser vaporization, may be dependent on the vaporized volume obtained after the procedure.

  20. Laser beam interactions with vapor plumes during Nd:YAG laser welding on aluminum

    NASA Astrophysics Data System (ADS)

    Peebles, H. C.; Russo, A. J.; Hadley, G. R.; Akau, R. L.

    Welds produced on pure aluminum targets using pulsed Nd:YAG lasers can be accurately described using a relatively simple conduction mode heat transfer model provided that the fraction of laser energy absorbed is known and the amount of metal vaporized is smalled however at laser fluences commonly used in many production welding schedules significant aluminum vaporization does occur. The possible mechanisms have been identified which could result in laser beam attenuation by the vapor plume.

  1. Runaway electron beam control for longitudinally pumped metal vapor lasers

    NASA Astrophysics Data System (ADS)

    Kolbychev, G. V.; Kolbycheva, P. D.

    1995-08-01

    Physics and techniques for producing of the pulsed runaway electron beams are considered. The main obstacle for increasing electron energies in the beams is revealed to be a self- breakdown of the e-gun's gas-filled diode. Two methods to suppress the self-breakdown and enhance the volumetric discharge producing the e-beam are offered and examined. Each of them provides 1.5 fold increase of the ceiling potential on the gun. The methods also give the ways to control several guns simultaneously. Resulting in the possibility of realizing the powerful longitudinal pumping of metal-vapor lasers on self-terminated transitions of atoms or ions.

  2. PRR performance of Cu- and CuBr-vapor lasers

    NASA Astrophysics Data System (ADS)

    Fedorov, V. F.; Evtushenko, Gennadiy S.; Klimkin, Vladimir M.; Polunin, Yu. P.; Soldatov, Anatoly N.; Sukhanov, Viktor B.

    1998-06-01

    Results obtained from comparative analysis of the pulse repetition rate performance of Cu- and CuBr-vapor lasers operated at high pump pulse repetitions (approximately 100 kHz) are reported. For a CuBr laser with a 8 mm diameter discharge tube the laser pulse repetition rate as high as 270 kHz was realized.

  3. Analysis of organic vapors with laser induced breakdown spectroscopy

    SciTech Connect

    Nozari, Hadi; Tavassoli, Seyed Hassan; Rezaei, Fatemeh

    2015-09-15

    In this paper, laser induced breakdown spectroscopy (LIBS) is utilized in the study of acetone, ethanol, methanol, cyclohexane, and nonane vapors. Carbon, hydrogen, oxygen, and nitrogen atomic emission spectra have been recorded following laser-induced breakdown of the organic vapors that are mixed with air inside a quartz chamber at atmospheric pressure. The plasma is generated with focused, Q-switched Nd:YAG radiation at the wavelength of 1064 nm. The effects of ignition and vapor pressure are discussed in view of the appearance of the emission spectra. The recorded spectra are proportional to the vapor pressure in air. The hydrogen and oxygen contributions diminish gradually with consecutive laser-plasma events without gas flow. The results show that LIBS can be used to characterize organic vapor.

  4. Computer simulated rate processes in copper vapor lasers

    NASA Technical Reports Server (NTRS)

    Harstad, K. C.

    1980-01-01

    A computer model for metal vapor lasers has been developed which places emphasis on the change of excited state populations of the lasant through inelastic collisions and radiative interaction. Also included are an energy equation for the pumping electrons and rate equations for laser photon densities. Presented are results of calculations for copper vapor with a neon buffer over a range of conditions. General agreement with experiments was obtained.

  5. A heated vapor cell unit for dichroic atomic vapor laser lock in atomic rubidium.

    PubMed

    McCarron, Daniel J; Hughes, Ifan G; Tierney, Patrick; Cornish, Simon L

    2007-09-01

    The design and performance of a compact heated vapor cell unit for realizing a dichroic atomic vapor laser lock (DAVLL) for the D(2) transitions in atomic rubidium is described. A 5 cm long vapor cell is placed in a double-solenoid arrangement to produce the required magnetic field; the heat from the solenoid is used to increase the vapor pressure and correspondingly the DAVLL signal. We have characterized experimentally the dependence of important features of the DAVLL signal on magnetic field and cell temperature. For the weaker transitions both the amplitude and gradient of the signal are increased by an order of magnitude.

  6. A heated vapor cell unit for dichroic atomic vapor laser lock in atomic rubidium

    NASA Astrophysics Data System (ADS)

    McCarron, Daniel J.; Hughes, Ifan G.; Tierney, Patrick; Cornish, Simon L.

    2007-09-01

    The design and performance of a compact heated vapor cell unit for realizing a dichroic atomic vapor laser lock (DAVLL) for the D2 transitions in atomic rubidium is described. A 5 cm long vapor cell is placed in a double-solenoid arrangement to produce the required magnetic field; the heat from the solenoid is used to increase the vapor pressure and correspondingly the DAVLL signal. We have characterized experimentally the dependence of important features of the DAVLL signal on magnetic field and cell temperature. For the weaker transitions both the amplitude and gradient of the signal are increased by an order of magnitude.

  7. Nonresonant femtosecond laser vaporization of aqueous protein preserves folded structure

    PubMed Central

    Brady, John J.; Judge, Elizabeth J.; Levis, Robert J.

    2011-01-01

    Femtosecond laser vaporization-based mass spectrometry can be used to measure protein conformation in vitro at atmospheric pressure. Cytochrome c and lysozyme are vaporized from the condensed phase into the gas phase intact when exposed to an intense (1013 W/cm2), nonresonant (800 nm), ultrafast (75 fs) laser pulse. Electrospray postionization time-of-flight mass spectrometry reveals that the vaporized protein maintains the solution-phase conformation through measurement of the charge-state distribution and the collision-induced dissociation channels. PMID:21746908

  8. Alexandrite laser transmitter development for airborne water vapor DIAL measurements

    NASA Technical Reports Server (NTRS)

    Chyba, Thomas H.; Ponsardin, Patrick; Higdon, Noah S.; DeYoung, Russell J.; Browell, Edward V.

    1995-01-01

    In the DIAL technique, the water vapor concentration profile is determined by analyzing the lidar backscatter signals for laser wavelengths tuned 'on' and 'off' a water vapor absorption line. Desired characteristics of the on-line transmitted laser beam include: pulse energy greater than or equal to 100 mJ, high-resolution tuning capability (uncertainty less than 0.25 pm), good spectral stability (jitter less than 0.5 pm about the mean), and high spectral purity (greater than 99 percent). The off-line laser is generally detuned less than 100 pm away from the water vapor line. Its spectral requirements are much less stringent. In our past research, we developed and demonstrated the airborne DIAL technique for water vapor measurements in the 720-nm spectral region using a system based on an alexandrite laser as the transmitter for the on-line wavelength and a Nd:YAG laser-pumped dye laser for the off-line wavelength. This off-line laser has been replaced by a second alexandrite laser. Diode lasers are used to injection seed both lasers for frequency and linewidth control. This eliminates the need for the two intracavity etalons utilized in our previous alexandrite laser and thereby greatly reduces the risk of optical damage. Consequently, the transmitted pulse energy can be substantially increased, resulting in greater measurement range, higher data density, and increased measurement precision. In this paper, we describe the diode injection seed source, the two alexandrite lasers, and the device used to line lock the on-line seed source to the water vapor absorption feature.

  9. Determining the stable isotope composition of pore water from saturated and unsaturated zone core: improvements to the direct vapor equilibration laser spectroscopy method

    NASA Astrophysics Data System (ADS)

    Hendry, M. J.; Schmeling, E.; Wassenaar, L. I.; Barbour, S. L.; Pratt, D.

    2015-06-01

    A method to measure the δ2H and δ18O composition of pore waters in saturated and unsaturated geologic core samples using direct vapor equilibration and laser spectroscopy (DVE-LS) was first described in 2008, and has since been widely adopted by others. Here, we describe a number of important methodological improvements and limitations encountered in routine application of DVE-LS over several years. Generally, good comparative agreement and accuracy is obtained between core pore water isotopic data obtained using DVE-LS and that measured on water squeezed from the same core. In complex hydrogeologic settings, high-resolution DVE-LS depth profiles provide greater spatial resolution of isotopic profiles compared to long-screened or nested piezometers. When fluid is used during drilling and coring (e.g., water rotary or wet sonic drill methods), spiking the drill fluid with 2H can be conducted to identify core contamination. DVE-LS analyses yield accurate formational isotopic data for fine-textured core (e.g., clay, shale) samples, but are less effective for cores obtained from saturated permeable (e.g., sand, gravels) geologic media or on chip samples that are easily contaminated by wet rotary drilling fluid. Data obtained from DVE-LS analyses of core samples collected using wet (contamination by drill water) and dry sonic (water loss by heating) methods were also problematic. Accurate DVE-LS results can be obtained on core samples with gravimetric water contents < 5 % by increasing the sample size tested. Inexpensive Ziploc™ gas sampling bags were determined to be as good as, if not better, than other, more expensive bags. Sample storage in gas tight sample bags provides acceptable results for up to 10 days of storage; however, measureable water loss and evaporitic isotopic enrichment occurs for samples stored for up to 6 months. With appropriate care taken during sample collection and storage, the DVE-LS approach for obtaining high resolution pore water

  10. Industrial applications of high-power copper vapor lasers

    SciTech Connect

    Warner, B.E.; Boley, C.D.; Chang, J.J.; Dragon, E.P.; Havstad, M.A.; Martinez, M.; McLean, W. II

    1995-08-01

    A growing appreciation has developed in the last several years for the copper vapor laser because of its utility in ablating difficult materials at high rates. Laser ablation at high rates shows promise for numerous industrial applications such as thin film deposition, precision hole drilling, and machining of ceramics and other refractories.

  11. Development of a strontium vapor laser with pulse repetition frequency up to 1 MHz

    NASA Astrophysics Data System (ADS)

    Soldatov, A. N.; Yudin, N. A.; Polunin, Yu. P.; Vasilieva, A. V.; Chebotarev, G. D.; Latush, E. L.; Fesenko, A. A.

    2010-09-01

    The problem of obtaining high pulse repetition frequencies in metal vapor lasers is urgent from the viewpoint of laser application to various technologies, increase of productivity of industrial laser systems, study of transient processes, etc. In addition, the high pulse repetition frequency provides large average laser radiation power in spite of a rather low energy extracted from a single lasing pulse. In this work, the possibility of increasing the pulse repetition frequency of a laser on self-terminated strontium ion transitions was investigated. The double pulse method was used to demonstrate experimentally that a pulse repetition frequency of ~1 MHz could be achieved at wavelengths of 1.03 and 1.09 μm of the strontium vapor laser. To explain the results obtained, the kinetics of the active medium was modeled using the self-consistent mathematical model of a He- Sr+ laser.

  12. Laser absorption spectroscopy system for vaporization process characterization and control

    SciTech Connect

    Galkowski, J.; Hagans, K.

    1993-09-07

    In support of the Lawrence Livermore National Laboratory`s (LLNL`s) Uranium Atomic Vapor Laser Isotope Separation (U-AVLIS) Program, a laser atomic absorption spectroscopy (LAS) system has been developed. This multi-laser system is capable of simultaneously measuring the line densities of {sup 238}U ground and metastable states, {sup 235}U ground and metastable states, iron, and ions at up to nine locations within the separator vessel. Supporting enrichment experiments that last over one hundred hours, this laser spectroscopy system is employed to diagnose and optimize separator system performance, control the electron beam vaporizer and metal feed systems, and provide physics data for the validation of computer models. As a tool for spectroscopic research, vapor plume characterization, vapor deposition monitoring, and vaporizer development, LLNL`s LAS laboratory with its six argon-ion-pumped ring dye lasers and recently added Ti:Sapphire and external-cavity diode-lasers has capabilities far beyond the requirements of its primary mission.

  13. Vaporization chambers and associated methods

    DOEpatents

    Turner, Terry D.; Wilding, Bruce M.; McKellar, Michael G.; Shunn, Lee P.

    2017-02-21

    A vaporization chamber may include at least one conduit and a shell. The at least one conduit may have an inlet at a first end, an outlet at a second end and a flow path therebetween. The shell may surround a portion of each conduit and define a chamber surrounding the portion of each conduit. Additionally, a plurality of discrete apertures may be positioned at longitudinal intervals in a wall of each conduit, each discrete aperture of the plurality of discrete apertures sized and configured to direct a jet of fluid into each conduit from the chamber. A liquid may be vaporized by directing a first fluid comprising a liquid into the inlet at the first end of each conduit, directing jets of a second fluid into each conduit from the chamber through discrete apertures in a wall of each conduit and transferring heat from the second fluid to the first fluid.

  14. Profiling atmospheric water vapor using a fiber laser lidar system.

    PubMed

    De Young, Russell J; Barnes, Norman P

    2010-02-01

    A compact, lightweight, and efficient fiber laser lidar system has been developed to measure water vapor profiles in the lower atmosphere of Earth or Mars. The line narrowed laser consist of a Tm:germanate fiber pumped by two 792 nm diode arrays. The fiber laser transmits approximately 0.5 mJ Q- switched pulses at 5 Hz and can be tuned to water vapor lines near 1.94 microm with linewidth of approximately 20 pm. A lightweight lidar receiver telescope was constructed of carbon epoxy fiber with a 30 cm Fresnel lens and an advanced HgCdTe APD detector. This system has made preliminary atmospheric measurements.

  15. Microcomponents manufacturing for precise devices by copper vapor laser

    NASA Astrophysics Data System (ADS)

    Gorny, Sergey; Nikonchuk, Michail O.; Polyakov, Igor V.

    2001-06-01

    This paper presents investigation results of drilling of metal microcomponents by copper vapor laser. The laser consists of master oscillator - spatial filter - amplifier system, electronics switching with digital control of laser pulse repetition rate and quantity of pulses, x-y stage with computer control system. Mass of metal, removed by one laser pulse, is measured and defined by means of diameter and depth of holes. Interaction of next pulses on drilled material is discussed. The difference between light absorption and metal evaporation processes is considered for drilling and cutting. Efficiency of drilling is estimated by ratio of evaporation heat and used laser energy. Maximum efficiency of steel cutting is calculated with experimental data of drilling. Applications of copper vapor laser for manufacturing is illustrated by such microcomponents as pin guide plate for printers, stents for cardio surgery, encoded disks for security systems and multiple slit masks for spectrophotometers.

  16. Diode pumped alkali vapor lasers for high power applications

    NASA Astrophysics Data System (ADS)

    Zweiback, J.; Krupke, B.; Komashko, A.

    2008-02-01

    General Atomics has been engaged in the development of diode pumped alkali vapor lasers. We have been examining the design space looking for designs that are both efficient and easily scalable to high powers. Computationally, we have looked at the effect of pump bandwidth on laser performance. We have also looked at different lasing species. We have used an alexandrite laser to study the relative merits of different designs. We report on the results of our experimental and computational studies.

  17. Solar-powered alkali metal vapor lasers

    NASA Technical Reports Server (NTRS)

    Blount, Charles E.

    1989-01-01

    The emission spectrum of the A(1 Sigma u +) - X(1 Sigma g +) band of Na2 has been recorded following excitation by monochromatic radiation in the region of X-A and X-B absorption. The spectral profile has been investigated as a function of excitation wavelength, sodium vapor temperature and buffer gas pressure. Additionally, gain measurements were made for the satellite of the A-X band as a function of the sodium vapor temperature and buffer gas pressure.

  18. Exploratory laser experiments. [measurement of atmospheric water vapor via optical radar

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Experiments are described which were undertaken to explore the application of various dye laser methods for generating laser pulses which could be tuned over H2O absorption lines in the visible and near infrared. Specific topics discussed include: operation of a long pulse dye laser with a tunable, narrow band output at high energies near the 5915 A water vapor absorption bands; assembly and operation of a short duration dye laser near the 5915 A water vapor absorption bands; construction of a dye laser to be pumped to operate in the red and near infrared; and preliminary studies of the beam divergence of the output of the a laser-pumped system. Results are summarized.

  19. High power diode pumped alkali vapor lasers

    NASA Astrophysics Data System (ADS)

    Zweiback, J.; Krupke, B.

    2008-05-01

    Diode pumped alkali lasers have developed rapidly since their first demonstration. These lasers offer a path to convert highly efficient, but relatively low brightness, laser diodes into a single high power, high brightness beam. General Atomics has been engaged in the development of DPALs with scalable architectures. We have examined different species and pump characteristics. We show that high absorption can be achieved even when the pump source bandwidth is several times the absorption bandwidth. In addition, we present experimental results for both potassium and rubidium systems pumped with a 0.2 nm bandwidth alexandrite laser. These data show slope efficiencies of 67% and 72% respectively.

  20. Multimode-diode-pumped gas (alkali-vapor) laser

    SciTech Connect

    Page, R H; Beach, R J; Kanz, V K

    2005-08-22

    We report the first demonstration of a multimode-diode-pumped gas laser--Rb vapor operating on the 795 nm resonance transition. Peak output of {approx}1 Watt was obtained using a volume-Bragg-grating stabilized pump diode array. The laser's output radiance exceeded the pump radiance by a factor greater than 2000. Power scaling (by pumping with larger diode arrays) is therefore possible.

  1. Carbon dioxide laser vaporization of facial siliconomas: flash in the pan or way of the future?

    PubMed

    Chui, Christopher Hoe Kong; Fong, Poh Him

    2008-03-01

    In 1988, Becker first described the "laser silicone flash" encountered while using the CO2 laser to remove breast siliconosis, but no subsequent use of the CO2 laser to remove siliconomas has been reported since. To our knowledge, lasers have not been described to treat facial silicone granulomas. Three cases of facial silicone granuloma (cheek, upper eyelids, and chin) were treated using the technique of CO2 laser vaporization.We describe a novel and effective method to remove facial siliconomas. This technique could avoid the need for radical resection of functional facial tissues such as nerves. Tiny globules of injected silicone in the face were vaporized without any untoward effects. Whether larger siliconomas can be treated in the same way remains to be seen and is an area of potential study.

  2. Laser diode array pumped continuous wave Rubidium vapor laser.

    PubMed

    Zhdanov, B V; Stooke, A; Boyadjian, G; Voci, A; Knize, R J

    2008-01-21

    We have demonstrated continuous wave operation of a laser diode array pumped Rb laser with an output power of 8 Watts. A slope efficiency of 60% and a total optical efficiency of 45% were obtained with a pump power of 18 Watts. This laser can be scaled to higher powers by using multiple laser diode arrays or stacks of arrays.

  3. Nd:Glass-Raman laser for water vapor dial

    NASA Technical Reports Server (NTRS)

    Kagann, R. H.; Petheram, J. C.; Rosenberg, A.

    1986-01-01

    A tunable solid-state Raman shifted laser which was used in a water vapor Differential Absorption Lidar (DIAL) system at 9400 A is described. The DIAL transmitter is based on a tunable glass laser operating at 1.06 microns, a hydrogen Raman cell to shift the radiation to 1.88 microns, and a frequency doubling crystal. The results of measurements which characterize the output of the laser with respect to optimization of optical configuration and of Raman parameters were reported. The DIAL system was also described and preliminary atmospheric returns shown.

  4. Method for laser machining explosives and ordnance

    SciTech Connect

    Muenchausen, Ross E.; Rivera, Thomas; Sanchez, John A.

    2003-05-06

    Method for laser machining explosives and related articles. A laser beam is directed at a surface portion of a mass of high explosive to melt and/or vaporize the surface portion while directing a flow of gas at the melted and/or vaporized surface portion. The gas flow sends the melted and/or vaporized explosive away from the charge of explosive that remains. The method also involves splitting the casing of a munition having an encased explosive. The method includes rotating a munition while directing a laser beam to a surface portion of the casing of an article of ordnance. While the beam melts and/or vaporizes the surface portion, a flow of gas directed at the melted and/or vaporized surface portion sends it away from the remaining portion of ordnance. After cutting through the casing, the beam then melts and/or vaporizes portions of the encased explosive and the gas stream sends the melted/vaporized explosive away from the ordnance. The beam is continued until it splits the article, after which the encased explosive, now accessible, can be removed safely for recycle or disposal.

  5. Study of Laser Created Metal Vapor Plasmas.

    DTIC Science & Technology

    1979-11-16

    the past year. We now have two nitrogen laser pumped dye lasers and a dual wavelength photodetection system. We have a new low pressure ablation chffber...ablation chamber and improved photodetection system is shcw in the foreground An RCA C31034 P’r and a SPEX 1700 monochromator is used in one cha-nel, while...independent, photodetection channels and a new fast dual bean oscilloscope. L13)1S - Theoretical Progrc-=, Over the past two years we have developed

  6. Growth of Carbon Nanostructure Materials Using Laser Vaporization

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, Ching-Hua; Lehozeky, S.

    2000-01-01

    Since the potential applications of carbon nanotubes (CNT) was discovered in many fields, such as non-structure electronics, lightweight composite structure, and drug delivery, CNT has been grown by many techniques in which high yield single wall CNT has been produced by physical processes including arc vaporization and laser vaporization. In this presentation, the growth mechanism of the carbon nanostructure materials by laser vaporization is to be discussed. Carbon nanoparticles and nanotubes have been synthesized using pulsed laser vaporization on Si substrates in various temperatures and pressures. Two kinds of targets were used to grow the nanostructure materials. One was a pure graphite target and the other one contained Ni and Co catalysts. The growth temperatures were 600-1000 C and the pressures varied from several torr to 500 torr. Carbon nanoparticles were observed when a graphite target was used, although catalysts were deposited on substrates before growing carbon films. When the target contains catalysts, carbon nanotubes (CNT) are obtained. The CNT were characterized by scanning electron microscopy, x-ray diffraction, optical absorption and transmission, and Raman spectroscopy. The temperature-and pressure-dependencies of carbon nanotubes' growth rate and size were investigated.

  7. Corona Charged Polypropylene Films Irradiated by CO2 and CuBr Vapor Lasers

    NASA Astrophysics Data System (ADS)

    Yovcheva, T. A.; Eftimov, T. A.; Viraneva, A. P.; Mekishev, G. A.; Yanev, V. C.; Avramova, I. A.

    2007-04-01

    The influence of CuBr vapor (Cu-Br) and CO2 laser radiation on polypropylene corona electrets is investigated in the present paper. The surface potential was measured before (V0) and after (Virr) irradiation using the method of the vibrating electrode with compensation. The sample surfaces were characterized by XPS.

  8. Water vapor absorption of carbon dioxide laser radiation

    NASA Technical Reports Server (NTRS)

    Shumate, M. S.; Menzies, R. T.; Margolis, J. S.; Rosengren, L.-G.

    1976-01-01

    An optoacoustic detector or spectrophone has been used to perform detailed measurements of the absorptivity of mixtures of water vapor in air. A (C-12) (O-16)2 laser was used as the source, and measurements were made at forty-nine different wavelengths from 9.2 to 10.7 microns. The details of the optoacoustic detector and its calibration are presented, along with a discussion of its performance characteristics. The results of the measurements of water vapor absorption show that the continuum absorption in the wavelength range covered is 5-10% lower than previous measurements.

  9. Vaporization behavior of non-stoichiometric refractory carbide materials and direct observations of the vapor phase using laser diagnostics

    SciTech Connect

    Butt, D.P.; Wantuck, P.J.; Rehse, S.J.; Wallace, T.C. Sr.

    1993-09-01

    Transition metal and actinide carbides, such as ZrC or NbC and UC or ThC, exhibit a wide range of stoichiometry, and therefore vaporize incongruently. At long times, steady state vaporization can be achieved where relative concentrations of atomic species on solid surface equals that in the gas phase. The surface composition under these steady state conditions is termed the congruently vaporizing composition, (CVC). Modeling the vaporization or corrosion behavior of this dynamic process is complex and requires an understanding of how the surface composition changes with time and a knowledge of CVC, which is both temperature and atmosphere dependent. This paper describes vaporization and corrosion behavior of non-stoichiometric refractory carbide materials and, as an example, describes a thermokinetic model that characterizes the vaporization behavior of the complex carbide U{sub x}Zr{sub 1-x}C{sub y} in hydrogen at 2500 to 3200 K. This model demonstrates that steady state corrosion of U{sub x}Zr{sub l-x}C{sub y} is rate limited by gaseous transport of Zr where partial pressure of Zr is determined by CVC. This paper also briefly describes efforts to image and characterize the vapor phase above the surface of ZrC in static and flowing gas environments using planar laser induced fluorescence. We have developed the method for monitoring and controlling the corrosion behavior of nuclear fuels in nuclear thermal rockets. However, the techniques described can be used, to image boundary layers, and could be used verifying corrosion models.

  10. Laser-induced ionization of Na vapor

    SciTech Connect

    Wu, R.C.Y.; Judge, D.L.; Roussel, F.; Carre, B.; Breger, P.; Spiess, G.

    1982-01-01

    The production of Na/sub 2//sup +/ ions by off-resonant laser excitation in the 5800-6200A region mainly results from two-photon absorption by the Na/sub 2/ molecule to highly excited gerade states followed by (a) direct ionization by absorbing a third photon or (b) coupling to the molecular Na/sub 2/ D/sup 1/PI..mu.. Rydberg state which is subsequently ionized by absorbing a third photon. This mechanism, i.e., a two-photon resonance three photon ionization process, explains a recent experimental observation of Roussel et al. It is suggested that the very same mechanism is also responsible for a similar observation reported by Polak-Dingels et al in their work using two crossed Na beams. In the latter two studies the laser-induced associative ionization processes were reported to be responsible for producing the Na/sub 2//sup +/ ion. From the ratio of molecular to atomic concentration in the crossed beam experiment of Polak-Dingels et al we estimate that the cross section for producing Na/sub 2//sup +/ through laser-induced associative ionization is at least four orders of magnitude smaller than ionization through the two-photon resonance three photon ionization process in Na/sub 2/ molecules.

  11. Laser-induced ionization of Na vapor

    NASA Astrophysics Data System (ADS)

    Wu, C. Y. Robert; Judge, D. L.; Roussel, F.; Carré, B.; Breger, P.; Spiess, G.

    1982-09-01

    The production of Na2+ ions by off-resonant laser excitation in the 5800-6200Å region mainly results from two-photon absorption by the Na2 molecule to highly excited gerade states followed by (a) direct ionization by absorbing a third photon or (b) coupling to the molecular Na2 D1Πu Rydberg state which is subsequently ionized by absorbing a third photon. This mechanism, i.e., a two-photon resonance three photon ionization process, explains a recent experimental observation of Roussel et al. It is suggested that the very same mechanism is also responsible for a similar observation reported by Polak-Dingels et al in their work using two crossed Na beams. In the latter two studies the laser-induced associative ionization processes were reported to be responsible for producing the Na2+ ion. From the ratio of molecular to atomic concentration in the crossed beam experiment of Polak-Dingels et al. we estimate that the cross section for producing Na2+ through laser-induced associative ionization is at least four orders of magnitude smaller than ionization through the two-photon resonance three photon ionization process in Na2 molecules.

  12. Laser vaporization for the synthesis of nanoparticles and polymers containing metal particulates

    NASA Astrophysics Data System (ADS)

    Samy El-Shall, M.

    1996-10-01

    The application of laser ablation has been widely used for the synthesis and characterization of nanomaterials and film deposition. Of particular interest are the combinations of laser ablation techniques with other chemical and physical processes to synthesize new materials with novel properties. In this paper, we specifically address two areas of materials chemistry which promise far-reaching progress for the development of novel materials with unusual properties. The first area deals with the synthesis of polymeric materials containing ultrafine metal particles. This has been achieved by combining recent advances in laser vaporization/ionization of metals with the very fast propagation rates characteristic of ionic polymerization. In the experiments, laser vaporization of metal targets is used to generate ultrafine metal particles and cations which are capable of catalyzing the cationic polymerization of isobutylene. High molecular weight polymers containing submicron metal particles have been obtained. This method can lead to the generation of new polymeric materials with unique properties. In the second area, combination of laser vaporization of metals with gas phase chemical reactions followed by controlled condensation from the vapor phase is used to synthesize nanoscale metal oxide, carbide and nitride particles with controlled sizes and compositions. The microscale structures of the SiO 2 and Al 2O 3 particles exhibit interesting web-like morphology with a significant volume of voids. Raman, IR, XPS, mass spectrometric and electron microscopic studies of these particles will be presented. These materials may have special applications in catalysis and as reinforcing agents for liquid polymers.

  13. Diode laser based water vapor DIAL using modulated pulse technique

    NASA Astrophysics Data System (ADS)

    Pham, Phong Le Hoai; Abo, Makoto

    2014-11-01

    In this paper, we propose a diode laser based differential absorption lidar (DIAL) for measuring lower-tropospheric water vapor profile using the modulated pulse technique. The transmitter is based on single-mode diode laser and tapered semiconductor optical amplifier with a peak power of 10W around 800nm absorption band, and the receiver telescope diameter is 35cm. The selected wavelengths are compared to referenced wavelengths in terms of random error and systematic errors. The key component of modulated pulse technique, a macropulse, is generated with a repetition rate of 10 kHz, and the modulation within the macropulse is coded according to a pseudorandom sequence with 100ns chip width. As a result, we evaluate both single pulse modulation and pseudorandom coded pulse modulation technique. The water vapor profiles conducted from these modulation techniques are compared to the real observation data in summer in Japan.

  14. Metal Organic-Chemical Vapor Deposition fabrication of semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Thomas, C.

    1980-08-01

    The metal organic chemical vapor deposition (MO-CVD) process was studied and implemented in detail. Single crystal GaAs, and Ga(x)Al(1-x)As films were grown on GaAs by depositing metal organic alkyl gallium compounds in the presence of an arsine mixture. The metal organic chemical vapor deposition process allowed formation of the semiconductor compound directly on the heated substrate in only one hot temperature zone. With MO-CVD, semiconductor films can be efficiently produced by a more economical, less complicated process which will lend itself more easily than past fabrication procedures, to high quantity, high quality reproduction techniques of semiconductor lasers. Clearly MO-CVD is of interest to the communication industry where semiconductor lasers are used extensively in fiber optic communication systems, and similarly to the solar energy business where GaAs substrates are used as photoelectric cells.

  15. Raman-shifted dye laser for water vapor DIAL measurements

    NASA Technical Reports Server (NTRS)

    Grossmann, B. E.; Singh, U. N.; Cotnoir, L. J.; Wilkerson, T. D.; Higdon, N. S.; Browell, E. V.

    1987-01-01

    For improved DIAL measurements of water vapor in the upper troposphere or lower stratosphere, narrowband (about 0.03/cm) laser radiation at 720- and 940-nm wavelengths was generated by stimulated Raman scattering (SRS), using the narrow linewidth (about 0.02/cm) output of a Nd:YAG-pumped dye laser. For a hydrogen pressure of 350 psi, the first Stokes conversion efficiencies to 940 nm were 20 percent and 35 percent, when using a conventional and waveguide Raman cell, respectively. The linewidth of the first Stokes line at high cell pressures, and the inferred collisional broadening coefficients, agree well with those previously measured in spontaneous Raman scattering.

  16. 250W diode laser for low pressure Rb vapor pumping

    NASA Astrophysics Data System (ADS)

    Podvyaznyy, A.; Venus, G.; Smirnov, V.; Mokhun, O.; Koulechov, V.; Hostutler, D.; Glebov, L.

    2010-02-01

    The diode pumped alkali vapor lasers operating at subatmospheric pressure require developing of a new generation of high-power laser diode sources with about 10 GHz wide emission spectrum. The latest achievements in the technology of volume Bragg gratings (VBGs) recorded in photo-thermo-refractive glass opened new opportunities for the design and fabrication of compact external cavity laser diodes, diode bars and stacks with reflecting VBGs as output couplers. We present a diode laser system providing up to 250 W output power and emission spectral width of 20 pm (FWHM) at the wavelength of 780 nm. The stability and position of an emission wavelength is determined by the resonant wavelength of a VBG which is controlled by temperature. Stability of an emitting wavelength is within 5 pm. Thermal tuning of the wavelength provides maximum overlapping of emitting line with absorption spectrum of a Rb (rubidium)- cell. The designed system consists of 7 modules tuned to the same wavelength corresponding to D2 spectral line of Rb87 or Rb85 and coupled to a single output fiber. Analogous systems could be used for other Rb isotopes spectral lines as well as for lasers based on other alkali metal vapors (Cs and K) or any agents with narrow absorption lines.

  17. Copper-vapor laser in medical practice: gynecology

    NASA Astrophysics Data System (ADS)

    Chvykov, Vladimir V.; Zazulya, O. I.; Zemskov, Konstantin I.

    1993-10-01

    About 100 patients were treated for cervical erosion, cervical leukoplakia, and vulval warts in the Gynecology Department of the adult polyclinic of the Zelenograd Center of Medicine. Copper vapor laser (CVL) was used with output average power up to 4 W in two lines (510 nm, 578 nm). Pulse repetition rate was about 10 kHz, pulselength approximately 20 - 40 ns. Four to twelve procedures were sufficient to recover.

  18. High average power magnetic modulator for metal vapor lasers

    DOEpatents

    Ball, Don G.; Birx, Daniel L.; Cook, Edward G.; Miller, John L.

    1994-01-01

    A three-stage magnetic modulator utilizing magnetic pulse compression designed to provide a 60 kV pulse to a copper vapor laser at a 4.5 kHz repetition rate is disclosed. This modulator operates at 34 kW input power. The circuit includes a step up auto transformer and utilizes a rod and plate stack construction technique to achieve a high packing factor.

  19. Laser device and method

    SciTech Connect

    Myers, J. D.

    1985-06-25

    A simplified, relatively inexpensive laser device, wherein the laser elements are fixed in a body exoskeleton of electrical insulating material having a low coefficient of thermal expansion. The preferred embodiment includes a shotgun type laser filter having parallel bores which receive the laser flashlamp and laser rod in fixed relation in a body chamber. The reflector surrounds the laser filter and retains the filter within the body chamber. In the preferred method of this invention, several controlled lasing pulses are generated with each illumination pulse of the flashlamp, substantially increasing the efficiency of the laser device. The number of pulses is generally controlled by increasing the voltage to the flashlamp. The rapid multiple lasing pulses generate an elongated plasma in a fluid medium, such as the vitreous fluid body of an eye which makes the laser device extemely efficient for treating glaucoma and other medical treatments.

  20. Laser amplifier and method

    DOEpatents

    Backus, Sterling; Kapteyn, Henry C.; Murnane, Margaret M.

    1997-01-01

    Laser amplifiers and methods for amplifying a laser beam are disclosed. A representative embodiment of the amplifier comprises first and second curved mirrors, a gain medium, a third mirror, and a mask. The gain medium is situated between the first and second curved mirrors at the focal point of each curved mirror. The first curved mirror directs and focuses a laser beam to pass through the gain medium to the second curved mirror which reflects and recollimates the laser beam. The gain medium amplifies and shapes the laser beam as the laser beam passes therethough. The third mirror reflects the laser beam, reflected from the second curved mirror, so that the laser beam bypasses the gain medium and return to the first curved mirror, thereby completing a cycle of a ring traversed by the laser beam. The mask defines at least one beam-clipping aperture through which the laser beam passes during a cycle. The gain medium is pumped, preferably using a suitable pumping laser. The laser amplifier can be used to increase the energy of continuous-wave or, especially, pulsed laser beams including pulses of femtosecond duration and relatively high pulse rate.

  1. Laser amplifier and method

    DOEpatents

    Backus, S.; Kapteyn, H.C.; Murnane, M.M.

    1997-07-01

    Laser amplifiers and methods for amplifying a laser beam are disclosed. A representative embodiment of the amplifier comprises first and second curved mirrors, a gain medium, a third mirror, and a mask. The gain medium is situated between the first and second curved mirrors at the focal point of each curved mirror. The first curved mirror directs and focuses a laser beam to pass through the gain medium to the second curved mirror which reflects and recollimates the laser beam. The gain medium amplifies and shapes the laser beam as the laser beam passes therethrough. The third mirror reflects the laser beam, reflected from the second curved mirror, so that the laser beam bypasses the gain medium and return to the first curved mirror, thereby completing a cycle of a ring traversed by the laser beam. The mask defines at least one beam-clipping aperture through which the laser beam passes during a cycle. The gain medium is pumped, preferably using a suitable pumping laser. The laser amplifier can be used to increase the energy of continuous-wave or, especially, pulsed laser beams including pulses of femtosecond duration and relatively high pulse rate. 7 figs.

  2. Chemical vapor synthesis of nanocrystalline perovskites using laser flash evaporation of low volatility solid precursors

    NASA Astrophysics Data System (ADS)

    Winterer, Markus; Srdic, Vladimir V.; Djenadic, Ruzica; Kompch, Alexander; Weirich, Thomas E.

    2007-12-01

    One key requirement for the production of multinary oxide films by chemical vapor deposition (CVD) or nanocrystalline multinary oxides particles by chemical vapor synthesis (CVS) is the availability of precursors with high vapor pressure. This is especially the case for CVS where much higher production rates are required compared to thin films prepared by CVD. However, elements, which form low valent cations such as alkaline earth metals, are typically only available as solid precursors of low volatility, e.g., in form of β-diketonates. This study describes laser flash evaporation as precursor delivery method for CVS of nanocrystalline perovskites. Laser flash evaporation exploits the nonequilibrium evaporation of solid metal organic precursors of low vapor pressure by absorption of the infrared radiation of a CO2 laser. It is shown that stoichiometric, nanocrystalline particles consisting of SrZrO3 and SrTiO3 can be formed from corresponding mixtures of β-diketonates which are evaporated nonselectively and with high rates by laser flash evaporation.

  3. Chemical vapor synthesis of nanocrystalline perovskites using laser flash evaporation of low volatility solid precursors.

    PubMed

    Winterer, Markus; Srdic, Vladimir V; Djenadic, Ruzica; Kompch, Alexander; Weirich, Thomas E

    2007-12-01

    One key requirement for the production of multinary oxide films by chemical vapor deposition (CVD) or nanocrystalline multinary oxides particles by chemical vapor synthesis (CVS) is the availability of precursors with high vapor pressure. This is especially the case for CVS where much higher production rates are required compared to thin films prepared by CVD. However, elements, which form low valent cations such as alkaline earth metals, are typically only available as solid precursors of low volatility, e.g., in form of beta-diketonates. This study describes laser flash evaporation as precursor delivery method for CVS of nanocrystalline perovskites. Laser flash evaporation exploits the nonequilibrium evaporation of solid metal organic precursors of low vapor pressure by absorption of the infrared radiation of a CO(2) laser. It is shown that stoichiometric, nanocrystalline particles consisting of SrZrO(3) and SrTiO(3) can be formed from corresponding mixtures of beta-diketonates which are evaporated nonselectively and with high rates by laser flash evaporation.

  4. Apparatus and method to control atmospheric water vapor composition and concentration during dynamic cooling of biological tissues in conjunction with laser irradiations

    DOEpatents

    Nelson, J. Stuart; Anvari, Bahman; Tanenbaum, B. Samuel; Milner, Thomas E.

    1999-01-01

    Cryogen spray cooling of skin surface with millisecond cryogen spurts is an effective method for establishing a controlled temperature distribution in tissue and protecting the epidermis from nonspecific thermal injury during laser mediated dermatological procedures. Control of humidity level, spraying distance and cryogen boiling point is material to the resulting surface temperature. Decreasing the ambient humidity level results in less ice formation on the skin surface without altering the surface temperature during the cryogen spurt. For a particular delivery nozzle, increasing the spraying distance to 85 millimeters lowers the surface temperature. The methodology comprises establishing a controlled humidity level in the theater of operation of the irradiation site of the biological tissues before and/or during the cryogenic spray cooling of the biological tissue. At cold temperatures calibration was achieved by mounting a thermistor on a thermoelectric cooler. The thermal electric cooler was cooled from from 20.degree. C. to about -20.degree. C. while measuring its infrared emission.

  5. Scaling of strontium-vapor laser active volume

    NASA Astrophysics Data System (ADS)

    Soldatov, A. N.; Polunin, Yu. P.

    2008-01-01

    Variations in the energy performance of a self-terminating Sr-vapor laser (SrVL) are examined. The active laser volume is varied between 20 and 650 cm 3. A linear relation is revealed between the average power delivered by the SrVL and its active volume. The SrVL efficiency is found to increase with active volume and to be comparable with that of a copper-vapor laser for an active volume V = 650 cm 3 (0.45 %). As the volume is increased, the total lasing pulse duration increases from 30 to 120 ns. The beam divergence problems associated with the use of a Fabry-Perot cavity or an unstable resonator of the telescopic type are discussed. A total average power of 13.5 W is obtained from V = 650 cm 3 at a lasing PRR F = 19 kHz. The output power generated at different laser wavelengths is as follows: 10.4 W at λ = 6.456 μm, 2.6 W at λ = 3 μm, and 0.5 W at λ = 1 μm. The wavelength dependence of the lasing pulse duration is considered.

  6. Conversion of Laser Phase Noise to Amplitude Noise in a Resonant Atomic Vapor: The Role of Laser Linewidth

    DTIC Science & Technology

    2007-11-02

    fiber optic sensors ; atomic frequency standards, applied laser spectroscopy, laser chemistry, atmospheric propagation and beam control, LIDAR/LADAR...SMC-TR-99-11 AEROSPACE REPORT NO. TR-98(8555)-14 Conversion of Laser Phase Noise to Amplitude Noise in a Resonant Atomic Vapor: The Role of Laser ...1999 3. REPORT TYPE AND DATES COVERED 4. TITLE AND SUBTITLE Conversion of Laser Phase Noise to Amplitude Noise in a Resonant Atomic Vapor: The Role

  7. Tm:germanate Fiber Laser for Planetary Water Vapor Atmospheric Profiling

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; De Young, Russell

    2009-01-01

    The atmospheric profiling of water vapor is necessary for finding life on Mars and weather on Earth. The design and performance of a water vapor lidar based on a Tm:germanate fiber laser is presented.

  8. The Laser Damage Threshold for Materials and the Relation Between Solid-Melt and Melt-Vapor Interface Velocities

    SciTech Connect

    Khalil, Osama Mostafa

    2010-10-08

    Numerous experiments have demonstrated and analytic theories have predicted that there is a threshold for pulsed laser ablation of a wide range of materials. Optical surface damage threshold is a very complex and important application of high-power lasers. Optical damage may also be considered to be the initial phase of laser ablation. In this work it was determined the time required and the threshold energy of a layer of thickness to heat up. We used the Finite Difference method to simulate the process of laser-target interaction in three cases. Namely, the case before melting begins using a continuous wave (c.w) laser source and a pulsed laser source, the case after the first change of state (from solid to melt), and the case after the second change of state (from melt to vapor). And also study the relation between the solid-melt and melt-vapor interface velocities to have a commonsense of the laser ablation process.

  9. Wavelength diversity in optically pumped alkali vapor lasers

    NASA Astrophysics Data System (ADS)

    Perram, Glen P.

    2017-01-01

    Alternative wavelengths for optically pumped alkali vapor lasers have been developed using single photon excitation of higher lying P-states, stimulated Raman processes, two-photon excitation of S and D states, and electric quadruple excitation on S-D transitions. Two photon excitation of Cs 72D leads to competing and cascade lasing producing red and infrared lasers operating on the D-P transitions, followed by ultraviolet, blue, the standard near infrared DPAL transitions operating on P-S transitions. The S-D pump transitions are fully bleached at pump intensities exceeding 1 MW/cm2, allowing for lasing transitions that terminate on the ground state. The kinetics of these systems are complex due to competition for population inversion among the many optical transitions. An optically pumped mid-infrared rubidium pulsed, mirrorless laser has also been demonstrated in a heat pipe along both the 62P3/2 - 62S1/2 transition at 2.73 μm and the 62P1/2 - 62S1/2 transition at 2.79 μm with a maximum energy of 100 nJ. Performance improves dramatically as the rubidium vapor density is increased, in direct contradiction with the prior work. No scaling limitations associated with energy pooling or ionization kinetics have been observed. Practical application for infrared counter measures depends on the further development of blue diode pump sources. Finally, stimulated electronic Raman scattering and hyper-Raman processes in potassium vapor near the D1 and D2 lines have been observed using a stable resonator and pulsed laser excitation. First and second order Stokes and anti-Stokes lines were observed simultaneously and independently for a pump laser tuning range exceeding 70 cm-1. When the pump is tuned between the K D1 and D2 lines, an efficient hyper-Raman process dominates with a slope efficiency that exceeds 10%. Raman shifted laser may be useful as a target illuminator or atmospheric compensation beacon for a high power diode pumped alkali laser.

  10. Removal of Water Vapor in a Mist Singlet Oxygen Generator for Chemical Oxygen Iodine Laser

    NASA Astrophysics Data System (ADS)

    Muto, Shigeki; Endo, Masamori; Nanri, Kenzo; Fujioka, Tomoo

    2004-02-01

    The mist singlet oxygen generator (Mist-SOG) for a chemical oxygen iodine laser (COIL) has been developed in order to increase basic hydrogen peroxide (BHP) utilization. It was clarified that the Mist-SOG generated much more water vapor than conventional SOGs because the heat capacity of BHP is small. The water vapor deactivates the excited iodine and depresses the laser power. Therefore, a jet-cold trap was developed in order to remove the water vapor while maintaining a minimum deactivation of singlet oxygen. In this method, a nozzle was used to spray chilled H2O2 at 238 K as a thin layer directly to the gas flow to achieve a large specific surface area for water vapor. As a result, the water vapor mole fraction was reduced to 7% from 18% with the BHP utilization of 21% at the Cl2 consumption rate of 3.5 mmol/s (Cl2 input flow rate of 8.0 mmol/s) for 65-μm-diameter BHP droplets.

  11. From a metal vapor laser projection microscope to a laser monitor (by the 50 year-anniversary of metal vapor lasers)

    NASA Astrophysics Data System (ADS)

    Evtushenko, G. S.

    2015-12-01

    The paper presents the history of active optical systems development from a laser projection microscope to a laser monitor. The examples of object visualization and diagnostics of high speed processes hidden by the intense background radiation are discussed. These are the processes of laser-surface interaction, self-propagating high-temperature synthesis (SHS), the corona discharge in the air, the nanoparticle production process using a high-power fiber laser, and etc. The results obtained by different research groups suggest that high-speed metal vapor brightness amplifiers and active optical systems based on them need further research, development and novel applications.

  12. Method and Apparatus for Concentrating Vapors for Analysis

    DOEpatents

    Grate, Jay W.; Baldwin, David L.; Anheier, Jr., Norman C.

    2008-10-07

    An apparatus and method are disclosed for pre-concentrating gaseous vapors for analysis. The invention finds application in conjunction with, e.g., analytical instruments where low detection limits for gaseous vapors are desirable. Vapors sorbed and concentrated within the bed of the apparatus can be thermally desorbed achieving at least partial separation of vapor mixtures. The apparatus is suitable, e.g., for preconcentration and sample injection, and provides greater resolution of peaks for vapors within vapor mixtures, yielding detection levels that are 10-10,000 times better than for direct sampling and analysis systems. Features are particularly useful for continuous unattended monitoring applications.

  13. Analysis of temporal jitter in a copper vapor laser system

    NASA Astrophysics Data System (ADS)

    Kumar, D. Durga Praveen; Gantayet, L. M.; Singh, Sunita; Rawat, A. S.; Rana, Paramjit; V, Rajasree; Agarwalla, Sandeep K.; Chakravarthy, D. P.

    2012-02-01

    Temporal jitter in a magnetic pulse compression based copper vapor laser (CVL) system is analyzed by considering ripple present in the input dc power supply and ripple present in the magnetic core resetting power supply. It is shown that the jitter is a function of the ratio of operating voltage to the designed voltage, percentage ripple, and the total propagation delay of the magnetic pulse compression circuit. Experimental results from a CVL system operating at a repetition rate of 9 kHz are presented.

  14. Atomic vapor laser isotope separation using resonance ionization

    SciTech Connect

    Comaskey, B.; Crane, J.; Erbert, G.; Haynam, C.; Johnson, M.; Morris, J.; Paisner, J.; Solarz, R.; Worden, E.

    1986-09-01

    Atomic vapor laser isotope separation (AVLIS) is a general and powerful technique. A major present application to the enrichment of uranium for light-water power-reactor fuel has been under development for over 10 years. In June 1985, the Department of Energy announced the selection of AVLIS as the technology to meet the nation's future need for enriched uranium. Resonance photoionization is the heart of the AVLIS process. We discuss those fundamental atomic parameters that are necessary for describing isotope-selective resonant multistep photoionization along with the measurement techniques that we use. We illustrate the methodology adopted with examples of other elements that are under study in our program.

  15. Characterization of Vapor and Aerosol Flows by Photothermal Methods.

    DTIC Science & Technology

    2014-09-26

    transient Mie-scattering. The main parts of our experimental set-up have been shown previously5 . A Q-switched CO2 laser beam (pulse duration I ps...indicated beam separations in a nitrogen/ethanol vapor flow.The CO2 laser is fired at t-0. Signal decrease and broadening is in agreement with eq. (I...20. AUSTRACT (Confliu W tover@ aede It nemsaem iaind Identif by bleck numier) Pulsed laser heating is used to label aerosols or absorbing vapors

  16. 80-W green KTP laser used in photoselective laser vaporization of the prostrate by frequency doubling of Yb 3+ -doped large-mode area fiber laser

    NASA Astrophysics Data System (ADS)

    Xia, Hongxing; Li, Zhengjia

    2007-05-01

    Photoselective laser vaporization of the prostate (PVP) is the most promising method for the treatment of benign prostatic hyperplasia (BPH), but KTP lasers used in PVP with lamp-pumped are low efficient .To increase the efficiency , we develop a 80-W, 400kHz, linearly polarized green laser based on a frequency-doubled fiber laser. A polarization-maintaining large-mode area (LMA) fiber amplifier generate polarized 1064nm fundamental wave by amplifying the seed signal from a composite Cr 4+:YAG-Nd 3+:YAG crystal fiber laser. The fundamental wave is injected into a KTP crystal with confined temperature management to achieve second harmonic generation (SHG). The overall electrical efficiency to the green portion of the spectrum is 10%.80-W maintenance-free long-lifetime KTP laser obtained can well satisfy the need of PVP.

  17. Means and method for vapor generation

    DOEpatents

    Carlson, L.W.

    A liquid, in heat transfer contact with a surface heated to a temperature well above the vaporization temperature of the liquid, will undergo a multiphase (liquid-vapor) transformation from 0% vapor to 100% vapor. During this transition, the temperature driving force or heat flux and the coefficients of heat transfer across the fluid-solid interface, and the vapor percentage influence the type of heating of the fluid - starting as feedwater heating where no vapors are present, progressing to nucleate heating where vaporization begins and some vapors are present, and concluding with film heating where only vapors are present. Unstable heating between nucleate and film heating can occur, accompanied by possibly large and rapid temperature shifts in the structures. This invention provides for injecting into the region of potential unstable heating and proximate the heated surface superheated vapors in sufficient quantities operable to rapidly increase the vapor percentage of the multiphase mixture by perhaps 10 to 30% and thereby effectively shift the multiphase mixture beyond the unstable heating region and up to the stable film heating region.

  18. Means and method for vapor generation

    DOEpatents

    Carlson, Larry W.

    1984-01-01

    A liquid, in heat transfer contact with a surface heated to a temperature well above the vaporization temperature of the liquid, will undergo a multiphase (liquid-vapor) transformation from 0% vapor to 100% vapor. During this transition, the temperature driving force or heat flux and the coefficients of heat transfer across the fluid-solid interface, and the vapor percentage influence the type of heating of the fluid--starting as "feedwater" heating where no vapors are present, progressing to "nucleate" heating where vaporization begins and some vapors are present, and concluding with "film" heating where only vapors are present. Unstable heating between nucleate and film heating can occur, accompanied by possibly large and rapid temperature shifts in the structures. This invention provides for injecting into the region of potential unstable heating and proximate the heated surface superheated vapors in sufficient quantities operable to rapidly increase the vapor percentage of the multiphase mixture by perhaps 10-30% and thereby effectively shift the multiphase mixture beyond the unstable heating region and up to the stable film heating region.

  19. High-efficiency cluster laser vaporization sources based on Ti: sapphire lasers

    NASA Astrophysics Data System (ADS)

    Pellarin, M.; Cottancin, E.; Lerme, J.; Vialle, J.L.; Wolf, J.P.; Broyer, M.; Paillard, V.; Dupuis, V.; Perez, A.; Perez, J.P.; Tuaillon, J.; Melinon, P.

    1994-07-01

    A new laser vaporization source based on a flashlamp-pumped Ti:sapphire laser has been used to produce cluster beams. The performance is compared to the standard cluster sources based on neodyme YAG lasers. We show that the Ti:sapphire source is much more efficient: the clusters deposition rate are about 30 times higher, and larger clusters are produced. Finally the quality of nanostructured films is comparable to those obtained by the standard source, but the time deposition is 30 times shorter. This opens new possibilites for film growth by cluster deposition.

  20. High intensity vacuum ultraviolet and extreme ultraviolet production by noncollinear mixing in laser vaporized media

    NASA Astrophysics Data System (ADS)

    Todt, Michael A.; Albert, Daniel R.; Davis, H. Floyd

    2016-06-01

    A method is described for generating intense pulsed vacuum ultraviolet (VUV) and extreme ultraviolet (XUV) laser radiation by resonance enhanced four-wave mixing of commercial pulsed nanosecond lasers in laser vaporized mercury under windowless conditions. By employing noncollinear mixing of the input beams, the need of dispersive elements such as gratings for separating the VUV/XUV from the residual UV and visible beams is eliminated. A number of schemes are described, facilitating access to the 9.9-14.6 eV range. A simple and convenient scheme for generating wavelengths of 125 nm, 112 nm, and 104 nm (10 eV, 11 eV, and 12 eV) using two dye lasers without the need for dye changes is described.

  1. High intensity vacuum ultraviolet and extreme ultraviolet production by noncollinear mixing in laser vaporized media.

    PubMed

    Todt, Michael A; Albert, Daniel R; Davis, H Floyd

    2016-06-01

    A method is described for generating intense pulsed vacuum ultraviolet (VUV) and extreme ultraviolet (XUV) laser radiation by resonance enhanced four-wave mixing of commercial pulsed nanosecond lasers in laser vaporized mercury under windowless conditions. By employing noncollinear mixing of the input beams, the need of dispersive elements such as gratings for separating the VUV/XUV from the residual UV and visible beams is eliminated. A number of schemes are described, facilitating access to the 9.9-14.6 eV range. A simple and convenient scheme for generating wavelengths of 125 nm, 112 nm, and 104 nm (10 eV, 11 eV, and 12 eV) using two dye lasers without the need for dye changes is described.

  2. Alexandrite laser characterization and airborne lidar developments for water vapor DIAL measurements

    NASA Technical Reports Server (NTRS)

    Ponsardin, P.; Higdon, N. S.; Grossmann, B. E.; Browell, E. V.

    1991-01-01

    The spectral characteristics of an Alexandrite laser used for making water vapor DIAL measurements have been evaluated. The optical servo-system used to lock the laser wavelength on a water vapor absorption line is described. A brief description of the DIAL system is given and the data obtained with this lidar during flight tests in March 1990 are also presented.

  3. Gas and metal vapor lasers and applications; Proceedings of the Meeting, Los Angeles, CA, Jan. 22, 23, 1991

    NASA Astrophysics Data System (ADS)

    Kim, Jin J.; Tittel, Frank K.

    Various papers on gas and metal vapor lasers and applications are presented. Individual topics addressed include: high-power copper vapor laser development, modified off-axis unstable resonator for copper vapor laser, industrial applications of metal vapor lasers, newly developed excitation circuit for kHz pulsed lasers, copper vapor laser precision processing, development of solid state pulse power supply for copper vapor laser, multiple spectral structure of the 578.2-nm line for copper vapor laser, adsorption of bromine in CuBr laser, processing of polytetrafluoroethylene with high-power VUV laser radiation, characterization of a subpicosecond XeF(C - A) excimer laser, X-ray preionization for high-repetition-rate discharge excimer lasers. Also discussed are: investigation of microwave-pumped excimer and rare-gas laser transitions, influence of gas composition of XeCl laser performance, output power stabilization of a XeCl excimer laser by HCl gas injection, excimer laser machining of optical fiber taps, diagnostics of a compact UV-preionized XeCl laser with BCl3 halogen donor, blackbody-pumped CO32 lasers using Gaussian and waveguide cavities, chemical problems of high-power sealed-off CO lasers, laser action of Xe and Ne pumped by electron beam, process monitoring during CO2 laser cutting, double-pulsed TEA CO2 laser, superhigh-gain gas laser, high-power ns-pulse iodine laser provided with SBS mirror. (No individual items are abstracted in this volume)

  4. Stabilization and spectral characterization of an alexandrite laser for water vapor lidar measurements

    NASA Technical Reports Server (NTRS)

    Ponsardin, Patrick; Higdon, Noah S.; Grossman, Benoist E.; Browell, Edward V.

    1991-01-01

    A description of an optical system used to lock the alexandrite laser frequency on a water vapor absorption line is presented. The laser spectral characteristics, which include the spectral purity, the effect of the laser linewidth on the absorption, and the laser wavelength stability, are evaluated.

  5. Laser frequency translation: a new method.

    PubMed

    Poelker, M; Kumar, P; Ho, S T

    1991-12-01

    We demonstrate how the frequency of a single-mode cw dye laser can be translated by 1.772 GHz using stimulated Raman scattering in sodium vapor. The output of a sodium Raman laser, the frequency-translated beam, is shown to be highly correlated in frequency with the dye-laser pump beam. The bandwidth of the 1.772-GHz heterodyne beat signal between the two beams is found to be as narrow as 440 Hz, much narrower than the root-mean-square frequency jitter (~1 MHz) of the dye-laser pump beam. The Raman laser method can be used with materials other than sodium, such as cesium or magnesium, to obtain frequency translations of a magnitude that may not be easily attainable with acousto-optic or electro-optic techniques.

  6. Multiphoton laser ionization for energy conversion in barium vapor

    NASA Astrophysics Data System (ADS)

    Makdisi, Y.; Kokaj, J.; Afrousheh, K.; Mathew, J.; Nair, R.; Pichler, G.

    2013-03-01

    We have studied the ion detection of barium atoms in special heated ovens with a tungsten rod in the middle of the stainless steel tube. The tungsten rod was heated indirectly by the oven body heaters. A bias voltage between the cell body and the tungsten rod of 9 V was used to collect electrons, after the barium ions had been created. However, we could collect the electrons even without the bias voltage, although with ten times less efficiency. We studied the conditions for the successful bias-less thermionic signal detection using excimer/dye laser two-photon excitation of Rydberg states below and above the first ionization limit (two-photon wavelength at 475.79 nm). We employed a hot-pipe oven and heat-pipe oven (with inserted mesh) in order to generate different barium vapor distributions inside the oven. The thermionic signal increased by a factor of two under heat-pipe oven conditions.

  7. Accumulating microparticles and direct-writing micropatterns using a continuous-wave laser-induced vapor bubble.

    PubMed

    Zheng, Yajian; Liu, Hui; Wang, Yi; Zhu, Cong; Wang, Shuming; Cao, Jingxiao; Zhu, Shining

    2011-11-21

    Through the enhanced photothermal effect, which was achieved using a silver film, a low power weakly focused continuous-wave laser (532 nm) was applied to create a vapor bubble. A convective flow was formed around the bubble. Microparticles dispersed in water were carried by the convective flow to the vapor bubble and accumulated on the silver film. By moving the laser spot, we easily manipulated the location of the bubble, allowing us to direct-write micropatterns on the silver film with accumulated particles. The reported simple controllable accumulation method can be applied to bimolecular detection, medical diagnosis, and other related biochip techniques.

  8. Collinear laser spectroscopy of francium using online rubidium vapor neutralization and amplitude modulated lasers.

    PubMed

    Sell, J F; Gulyuz, K; Sprouse, G D

    2009-12-01

    Performing collinear laser spectroscopy on low intensity radioactive beams requires sensitive detection techniques. We explain our apparatus to detect atomic resonances in neutralized (208-210)Fr ion beams at beam energies of 5 keV and intensities of 10(5) s(-1). Efficient neutralization (> or = 80%) is accomplished by passing the beam through a dense Rb vapor. Increased detection efficiency is achieved by amplitude modulating the exciting laser to decrease the scattered light background, allowing fluorescence detection only when the laser is near its minimum in the modulation cycle. Using this technique in a collinear geometry we achieve a background reduction by a factor of 180 and a signal-to-noise increase of 2.2, with the lifetime of the atomic state playing a role in the efficiency of this process. Such laser modulation will also produce sidebands on the atomic spectra which we illustrate.

  9. Collinear laser spectroscopy of francium using online rubidium vapor neutralization and amplitude modulated lasers

    NASA Astrophysics Data System (ADS)

    Sell, J. F.; Gulyuz, K.; Sprouse, G. D.

    2009-12-01

    Performing collinear laser spectroscopy on low intensity radioactive beams requires sensitive detection techniques. We explain our apparatus to detect atomic resonances in neutralized F208-210r ion beams at beam energies of 5 keV and intensities of 105 s-1. Efficient neutralization (≥80%) is accomplished by passing the beam through a dense Rb vapor. Increased detection efficiency is achieved by amplitude modulating the exciting laser to decrease the scattered light background, allowing fluorescence detection only when the laser is near its minimum in the modulation cycle. Using this technique in a collinear geometry we achieve a background reduction by a factor of 180 and a signal-to-noise increase of 2.2, with the lifetime of the atomic state playing a role in the efficiency of this process. Such laser modulation will also produce sidebands on the atomic spectra which we illustrate.

  10. Collinear laser spectroscopy of francium using online rubidium vapor neutralization and amplitude modulated lasers

    SciTech Connect

    Sell, J. F.; Gulyuz, K.; Sprouse, G. D.

    2009-12-15

    Performing collinear laser spectroscopy on low intensity radioactive beams requires sensitive detection techniques. We explain our apparatus to detect atomic resonances in neutralized {sup 208-210}Fr ion beams at beam energies of 5 keV and intensities of 10{sup 5} s{sup -1}. Efficient neutralization ({>=}80%) is accomplished by passing the beam through a dense Rb vapor. Increased detection efficiency is achieved by amplitude modulating the exciting laser to decrease the scattered light background, allowing fluorescence detection only when the laser is near its minimum in the modulation cycle. Using this technique in a collinear geometry we achieve a background reduction by a factor of 180 and a signal-to-noise increase of 2.2, with the lifetime of the atomic state playing a role in the efficiency of this process. Such laser modulation will also produce sidebands on the atomic spectra which we illustrate.

  11. Simulation studies of vapor bubble generation by short-pulse lasers

    SciTech Connect

    Amendt, P.; London, R.A.; Strauss, M.

    1997-10-26

    Formation of vapor bubbles is characteristic of many applications of short-pulse lasers in medicine. An understanding of the dynamics of vapor bubble generation is useful for developing and optimizing laser-based medical therapies. To this end, experiments in vapor bubble generation with laser light deposited in an aqueous dye solution near a fiber-optic tip have been performed. Numerical hydrodynamic simulations have been developed to understand and extrapolate results from these experiments. Comparison of two-dimensional simulations with the experiment shows excellent agreement in tracking the bubble evolution. Another regime of vapor bubble generation is short-pulse laser interactions with melanosomes. Strong shock generation and vapor bubble generation are common physical features of this interaction. A novel effect of discrete absorption by melanin granules within a melanosome is studied as a possible role in previously reported high Mach number shocks.

  12. Simulation studies of vapor bubble generation by short-pulse lasers

    NASA Astrophysics Data System (ADS)

    Amendt, Peter A.; London, Richard A.; Strauss, Moshe; Glinsky, Michael E.; Maitland, Duncan J.; Celliers, Peter M.; Visuri, Steven R.; Bailey, David S.; Young, David A.; Ho, Darwin; Lin, Charles P.; Kelly, Michael W.

    1998-01-01

    Formation of vapor bubbles is characteristic of many applications of short-pulse lasers in medicine. An understanding of the dynamics of vapor bubble generation is useful for developing and optimizing laser-based medical therapies. To this end, experiments in vapor bubble generation with laser light deposited in an aqueous dye solution near a fiber-optic tip have been performed. Numerical hydrodynamic simulations have been developed to understand and extrapolate results from these experiments. Comparison of two-dimensional simulations with the experiment shows excellent agreement in tracking the bubble evolution. Another regime of vapor bubble generation is short-pulse laser interactions with melanosomes. Strong shock generation and vapor bubble generation are common physical features of this interaction. A novel effect of discrete absorption by melanin granules within a melanosome is studied as a possible role in previously reported high Mach number shocks [Lin and Kelly, SPIE 2391, 294 (1995)].

  13. Determination of gas-discharge plasma parameters in powerful metal halide vapor lasers

    NASA Astrophysics Data System (ADS)

    Temelkov, Krassimir A.; Slaveeva, Stefka I.; Fedchenko, Yulian I.

    2016-01-01

    Powerful metal halide vapor lasers are excited with nanosecond pulsed longitudinal discharge in complex multicomponent gas mixtures. Using a new method, thermal conductivity of various 5- and 6-component gas mixtures is obtained under gas-discharge conditions, which are optimal for laser operation on the corresponding metal atom and ion transitions. Assuming that the gas temperature varies only in the radial direction and using the calculated thermal conductivities, an analytical solution of the steady-state heat conduction equation is found for uniform and radially nonuniform power input in various laser tube constructions. Using the results obtained for time-resolved electron temperature by measurement of electrical discharge characteristics and analytically solving steady-state heat conduction equation for electrons as well, radial distribution of electron temperature is also obtained for the discharge period.

  14. Metal film deposition by laser breakdown chemical vapor deposition

    SciTech Connect

    Jervis, T. R.; Newkirk, L. R.

    1986-06-01

    Dielectric breakdown of gas mixtures can be used to deposit thin films by chemical vapor deposition with appropriate control of flow and pressure conditions to suppress gas-phase nucleation and particle formation. Using a pulsed CO/sub 2/ laser operating at 10.6 ..mu.. where there is no significant resonant absorption in any of the source gases, homogeneous films from several gas-phase precursors have been sucessfully deposited by gas-phase laser pyrolysis. Nickel and molybdenum from the respective carbonyls representing decomposition chemistry and tungsten from the hexafluoride representing reduction chemistry have been demonstrated. In each case the gas precursor is buffered with argon to reduce the partial pressure of the reactants and to induce breakdown. Films have been characterized by Auger electron spectroscopy, x-ray diffraction, transmission electron microscopy, pull tests, and resistivity measurements. The highest quality films have resulted from the nickel depositions. Detailed x-ray diffraction analysis of these films yields a very small domain size consistent with the low temperature of the substrate and the formation of metastable nickel carbide. Transmission electron microscopy supports this analysis.

  15. Laser pulse stacking method

    DOEpatents

    Moses, Edward I.

    1992-01-01

    A laser pulse stacking method is disclosed. A problem with the prior art has been the generation of a series of laser beam pulses where the outer and inner regions of the beams are generated so as to form radially non-synchronous pulses. Such pulses thus have a non-uniform cross-sectional area with respect to the outer and inner edges of the pulses. The present invention provides a solution by combining the temporally non-uniform pulses in a stacking effect to thus provide a more uniform temporal synchronism over the beam diameter.

  16. Laser pulse stacking method

    DOEpatents

    Moses, E.I.

    1992-12-01

    A laser pulse stacking method is disclosed. A problem with the prior art has been the generation of a series of laser beam pulses where the outer and inner regions of the beams are generated so as to form radially non-synchronous pulses. Such pulses thus have a non-uniform cross-sectional area with respect to the outer and inner edges of the pulses. The present invention provides a solution by combining the temporally non-uniform pulses in a stacking effect to thus provide a more uniform temporal synchronism over the beam diameter. 2 figs.

  17. Method for controlling corrosion in thermal vapor injection gases

    DOEpatents

    Sperry, John S.; Krajicek, Richard W.

    1981-01-01

    An improvement in the method for producing high pressure thermal vapor streams from combustion gases for injection into subterranean oil producing formations to stimulate the production of viscous minerals is described. The improvement involves controlling corrosion in such thermal vapor gases by injecting water near the flame in the combustion zone and injecting ammonia into a vapor producing vessel to contact the combustion gases exiting the combustion chamber.

  18. The threshold of vapor channel formation in water induced by pulsed CO2 laser

    NASA Astrophysics Data System (ADS)

    Guo, Wenqing; Zhang, Xianzeng; Zhan, Zhenlin; Xie, Shusen

    2012-12-01

    Water plays an important role in laser ablation. There are two main interpretations of laser-water interaction: hydrokinetic effect and vapor phenomenon. The two explanations are reasonable in some way, but they can't explain the mechanism of laser-water interaction completely. In this study, the dynamic process of vapor channel formation induced by pulsed CO2 laser in static water layer was monitored by high-speed camera. The wavelength of pulsed CO2 laser is 10.64 um, and pulse repetition rate is 60 Hz. The laser power ranged from 1 to 7 W with a step of 0.5 W. The frame rate of high-speed camera used in the experiment was 80025 fps. Based on high-speed camera pictures, the dynamic process of vapor channel formation was examined, and the threshold of vapor channel formation, pulsation period, the volume, the maximum depth and corresponding width of vapor channel were determined. The results showed that the threshold of vapor channel formation was about 2.5 W. Moreover, pulsation period, the maximum depth and corresponding width of vapor channel increased with the increasing of the laser power.

  19. Performance characteristics of a chemical oxygen-iodine laser without a water vapor trap

    NASA Astrophysics Data System (ADS)

    Kikuchi, Toshio; Tsuruyama, Toru; Uchiyama, Taro

    1988-09-01

    The effect of water vapor on the operation of a chemical oxygen-iodine laser without a water vapor trap is described. The maximum CW laser power of 87 W was obtained without the water vapor trap at a Cl2 flow rate of 740 mmol/min. An alkaline H2O2 solution (90 wt pct H2O2, 50 wt pct KOH) was cooled down to about -30 C in order to control the saturated H2O2-H2O vapor pressure to less than 100 mTorr. Two porous pipes made of carbon were utilized as a singlet oxygen generator.

  20. Fabrication of highly ultramicroporous carbon nanofoams by SF6-catalyzed laser-induced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Hattori, Yoshiyuki; Shuhara, Ai; Kondo, Atsushi; Utsumi, Shigenori; Tanaka, Hideki; Ohba, Tomonori; Kanoh, Hirofumi; Takahashi, Kunimitsu; Vallejos-Burgos, Fernando; Kaneko, Katsumi

    2016-05-01

    We have developed a laser-induced chemical vapor deposition (LCVD) method for preparing nanocarbons with the aid of SF6. This method would offer advantages for the production of aggregates of nanoscale foams (nanofoams) at high rates. Pyrolysis of the as-grown nanofoams induced the high surface area (1120 m2 g-1) and significantly enhanced the adsorption of supercritical H2 (16.6 mg g-1 at 77 K and 0.1 MPa). We also showed that the pyrolized nanofoams have highly ultramicroporous structures. The pyrolized nanofoams would be superior to highly microporous nanocarbons for the adsorption of supercritical gases.

  1. Method and apparatus for isotope-selectively exciting gaseous or vaporous uranium hexafluoride molecules

    SciTech Connect

    Fill, E.E.; Jetter, H.L.; Volk, R.

    1981-06-09

    A method of isotope-selectively exciting gaseous or vaporous uranium hexafluoride molecules by subjecting them to the action of a monochromatic iodine laser beam, the frequency of which can be adjusted and tuned to an absorption band of the molecules to be excited, the laser beam being scattered by liquid and/or solid nitrogen to obtain a triple raman-scattering. In a preferred embodiment, the laser has an emission frequency of 7600 to 7610 cm-1 and the tuning is effected by means of a magnetic field. An apparatus suitable for carrying out such a method comprises a high-performance iodine laser and an optical resonator into which the emission beam or pulses of the laser are focused, one or more dewar vessels filled with liquid or solid nitrogen being located within the optical resonator. In a preferred embodiment, the laser beam tube is located between the poles of an electromagnet.

  2. Theoretical analysis of the semi-ring and trapezoid LD side-pumped alkali vapor lasers

    NASA Astrophysics Data System (ADS)

    Shen, Binglin; Xu, Xingqi; Xia, Chunsheng; Pan, Bailiang

    2016-12-01

    Analysis of two new pump-couplings: semi-ring and trapezoid LD side-pumped configurations in alkali vapor lasers is reported, which mainly includes the numerical approaches for evaluation of the pump intensity and temperature distribution in the cell of these two configurations. Comparison between the simulated results of the semi-ring and trapezoid LD side-pumped Cs vapor lasers and the experimental results of the single-side pumped Cs vapor lasers with a cylindrical white diffuse reflector and a stable or unstable resonator is made. Dependencies of laser power on pump power and flowed velocity for semi-ring, trapezoid, single and double side-pumped configurations are calculated, demonstrating the advantages of the semi-ring and trapezoid LD side-pumped configurations. Thus the model is very helpful for designing high-power side-pumped alkali vapor lasers.

  3. Method and apparatus for concentrating vapors for analysis

    DOEpatents

    Grate, Jay W [West Richland, WA; Baldwin, David L [Kennewick, WA; Anheier, Jr., Norman C.

    2012-06-05

    A pre-concentration device and a method are disclosed for concentrating gaseous vapors for analysis. Vapors sorbed and concentrated within the bed of the pre-concentration device are thermally desorbed, achieving at least partial separation of the vapor mixtures. The pre-concentration device is suitable, e.g., for pre-concentration and sample injection, and provides greater resolution of peaks for vapors within vapor mixtures, yielding detection levels that are 10-10,000 times better than direct sampling and analysis systems. Features are particularly useful for continuous unattended monitoring applications. The invention finds application in conjunction with, e.g., analytical instruments where low detection limits for gaseous vapors are desirable.

  4. Thermal electric vapor trap arrangement and method

    DOEpatents

    Alger, T.

    1988-03-15

    A technique for trapping vapor within a section of a tube is disclosed herein. This technique utilizes a conventional, readily providable thermal electric device having a hot side and a cold side and means for powering the device to accomplish this. The cold side of this device is positioned sufficiently close to a predetermined section of the tube and is made sufficiently cold so that any condensable vapor passing through the predetermined tube section is condensed and trapped, preferably within the predetermined tube section itself. 4 figs.

  5. Thermal electric vapor trap arrangement and method

    DOEpatents

    Alger, Terry

    1988-01-01

    A technique for trapping vapor within a section of a tube is disclosed herein. This technique utilizes a conventional, readily providable thermal electric device having a hot side and a cold side and means for powering the device to accomplish this. The cold side of this device is positioned sufficiently close to a predetermined section of the tube and is made sufficiently cold so that any condensable vapor passing through the predetermined tube section is condensed and trapped, preferably within the predetermined tube section itself.

  6. Method and apparatus for conducting variable thickness vapor deposition

    DOEpatents

    Nesslage, G.V.

    1984-08-03

    A method of vapor depositing metal on a substrate in variable thickness comprises conducting the deposition continuously without interruption to avoid formation of grain boundaries. To achieve reduced deposition in specific regions a thin wire or ribbon blocking body is placed between source and substrate to partially block vapors from depositing in the region immediately below.

  7. Metal film deposition by laser breakdown chemical vapor deposition

    SciTech Connect

    Jervis, T.R.

    1985-01-01

    Dielectric breakdown of gas mixtures can be used to deposit homogeneous thin films by chemical vapor deposition with appropriate control of flow and pressure conditions to suppress gas phase nucleation and particle formation. Using a pulsed CO/sub 2/ laser operating at 10.6 microns where there is no significant resonant absorption in any of the source gases, we have succeeded in depositing homogeneous films from several gas phase precursors by gas phase laser pyrolysis. Nickel and molybdenum from the respective carbonyls and tungsten from the hexafluoride have been examined to date. In each case the gas precursor is buffered to reduce the partial pressure of the reactants and to induce breakdown. The films are spectrally reflective and uniform over a large area. Films have been characterized by Auger electron spectroscopy, x-ray diffraction, pull tests, and resistivity measurements. The highest quality films have resulted from the nickel depositions. Detailed x-ray diffraction analysis of these films yields a very small domain size (approx. 50 A) consistent with rapid quenching from the gas phase reaction zone. This analysis also shows nickel carbide formation consistent with the temperature of the reaction zone and the Auger electron spectroscopy results which show some carbon and oxygen incorporation (8% and 1% respectively). Gas phase transport and condensation of the molybdenum carbonyl results in substantial carbon and oxygen contamination of the molybdenum films requiring heated substrates, a requirement not consistent with the goals of the program to maximize the quench rate of the deposition. Results from tungsten deposition experiments representing a reduction chemistry instead of the decomposition chemistry involved in the carbonyl experiments are also reported.

  8. Metal film deposition by laser breakdown chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Jervis, T. R.

    1985-01-01

    Dielectric breakdown of gas mixtures can be used to deposit homogeneous thin films by chemical vapor deposition with appropriate control of flow and pressure conditions to suppress gas phase nucleation and particle formation. Using a pulsed CO2 laser operating at 10.6 microns where there is no significant resonant absorption in any of the source gases, we have succeeded in depositing homogeneous films from several gas phase precursors by gas phase laser pyrolysis. Nickel and molybdenum from the respective carbonyls and tungsten from the hexafluoride have been examined to date. In each case the gas precursor is buffered to reduce the partial pressure of the reactants and to induce breakdown. The films are spectrally reflective and uniform over a large area. Films have been characterized by Auger electron spectroscopy, X-ray diffraction, pull tests, and resistivity measurements. The highest quality films have resulted from the nickel depositions. Detailed X-ray diffraction analysis of these films yields a very small domain size (approx. 50 A) consistent with rapid quenching from the gas phase reaction zone. This analysis also shows nickel carbide formation consistent with the temperature of the reaction zone and the Auger electron spectroscopy results which show some carbon and oxygen incorporation (8% and 1% respectively). Gas phase transport and condensation of the molybdenum carbonyl results in substantial carbon and oxygen contamination of the molybdenum films requiring heated substrates, a requirement not consistent with the goals of the program to maximize the quench rate of the deposition. Results from tungsten deposition experiments representing a reduction chemistry instead of the decomposition chemistry involved in the carbonyl experiments are also reported.

  9. Laser vaporization/ionization interface for coupling microscale separation techniques with mass spectrometry

    DOEpatents

    Yeung, Edward S.; Chang, Yu-chen

    1999-06-29

    The present invention provides a laser-induced vaporization and ionization interface for directly coupling microscale separation processes to a mass spectrometer. Vaporization and ionization of the separated analytes are facilitated by the addition of a light-absorbing component to the separation buffer or solvent.

  10. Laser vaporization/ionization interface for coupling microscale separation techniques with mass spectrometry

    DOEpatents

    Yeung, E.S.; Chang, Y.C.

    1999-06-29

    The present invention provides a laser-induced vaporization and ionization interface for directly coupling microscale separation processes to a mass spectrometer. Vaporization and ionization of the separated analytes are facilitated by the addition of a light-absorbing component to the separation buffer or solvent. 8 figs.

  11. Characteristics of a High Intensity, Pulsed, Potassium Vapor Laser in a Heat Pipe

    DTIC Science & Technology

    2011-03-01

    metals form the first column of the periodic table. From the top, this column includes lithium, sodium , potassium, rubidium, and cesium . They...pumped rubidium vapor laser by Krupke [2]. Since then, cesium (Cs), rubidium (Rb), and potassium (K) vapor lasers have been demonstrated and are the...would degrade the population inversion necessary for lasing to occur. Fortunately, the cesium and rubidium DPALs have much greater spin-orbit

  12. EPA Method 245.2: Mercury (Automated Cold Vapor Technique)

    EPA Pesticide Factsheets

    Method 245.2 describes procedures for preparation and analysis of drinking water samples for analysis of mercury using acid digestion and cold vapor atomic absorption. Samples are prepared using an acid digestion technique.

  13. Energy balance between vaporization and heating in the absorption of CO2 laser radiation by water

    NASA Astrophysics Data System (ADS)

    Mueller, Robert E.; Yam, Henry; Duley, Walter W.

    1997-03-01

    The use of lasers in industrial and medical procedures continues to increase. A fundamental question in many laser- material interactions is how is the incident laser power transferred to the target material, and how is the power distributed among the phases (solid, liquid, vapor) of the material. This paper describes the results of a fundamental calorimetry experiment to determine the fraction of incident carbon-dioxide laser energy which is used to vaporize water from a target volume, and the fraction of power used to simply heat the remaining liquid. The experiment was performed over a range of incident laser powers from 60 to 300 W. Over most of the range of incident power, the fraction used to vaporize water is 30 to 35 percent. This fraction increases at the lowest powers.

  14. 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.

  15. Advances in Diode-Laser-Based Water Vapor Differential Absorption Lidar

    NASA Astrophysics Data System (ADS)

    Spuler, Scott; Repasky, Kevin; Morley, Bruce; Moen, Drew; Weckwerth, Tammy; Hayman, Matt; Nehrir, Amin

    2016-06-01

    An advanced diode-laser-based water vapor differential absorption lidar (WV-DIAL) has been developed. The next generation design was built on the success of previous diode-laser-based prototypes and enables accurate measurement of water vapor closer to the ground surface, in rapidly changing atmospheric conditions, and in daytime cloudy conditions up to cloud base. The lidar provides up to 1 min resolution, 150 m range resolved measurements of water vapor in a broad range of atmospheric conditions. A description of the instrument and results from its initial field test in 2014 are discussed.

  16. Preliminary results on diode-laser assisted vaporization of prostate tissue

    NASA Astrophysics Data System (ADS)

    Sroka, Ronald; Seitz, Michael; Reich, Oliver; Bachmann, Alexander; Steinbrecher, Verena; Ackermann, Alexander; Stief, Christian

    2007-07-01

    Introduction and objectives: The aim was to identify the capability and the laser parameter of under water tissue vaporisation by means of a diode laser (1470 nm). Afterwards the feasibility and postoperative clinical outcome of vaporization of the prostate was investigated. Method: After acquiring suitable laser parameters in in-vitro experiments using a perfused tissue model patients (n=10) suffering from bladder outlet obstruction due to benign prostatic hyperplasia (BPH) were treated by diode laser. Their clinical outcome, in terms of acceptance and post-operatively voiding were evaluated. The diode laser emitted light of the wavelength of 1470 nm at 50 W (Biolitec GmbH) and delivered to the tissue by means of a side-fire fibre introduced through a 24F continuous-flow cystoscope. Normal saline was used for irrigation with an additive of 1% ethanol. The prostatic lobes (volume range 35-80ml) were vaporized within the prostatic capsular using sweeping and push and pull technique. The mean time of laser application was 2400 sec (1220-4000 sec) resulting in applied energies of 121 kJ in the mean (range: 61-200kJ). Results: During laser treatment none of the 10 patients showed any significant blood loss or any fluid absorption (no ethanol uptake). Foley catheters were removed between 18 and 168 hours postoperatively (mean: 49.8h+/-46h). After removal of the catheter the mean peak urine flow rate increased from 8.9ml/s +/- 2.9ml/s pre-operatively in comparison to 15.7ml/s +/- 5 ml/s (p=0.049) post-operatively. 8/10 patients were satisfied with their voiding outcome. None of the patients showed appearance of urgency, dysuria, hematuria, or incontinence but two patients required re-catheterization. After a follow-up of 1month, 8/10 patients showed evidence of good results and are satisfied with the outcome. Two patients required consecutive TUR-P. After a follow-up of 6-month the 8 patients are still satisfied. Conclusions: This very early and limited experience using

  17. Probing heat diffusion after pulsed-laser-induced breakdown in a metal vapor

    SciTech Connect

    Zapka, W.; Tam, A.C.

    1982-02-01

    We have used a pulsed dye-laser beam at 6010 A, of 1-..mu..sec duration and < or approx. =1-mJ energy, to produce a line plasma in a Cs metal vapor. This produces a line source of large thermal energy. The heat diffusion after the laser pulse can be studied by transmission monitoring of a weak cw He--Ne laser beam that is parallel to but separated from the pulse laser beam by an adjustable displacement. This is possible because the He--Ne beam is absorbed by the minority Cs/sub 2/ molecules but not by the majority Cs atoms; as the heat pulse diffuses through the probe beam, the transient temperature increase causes a corresponding change in the population distribution of the Cs/sub 2/ molecules and hence a transient increase in transmission of the probe beam. In other words, the Cs/sub 2/ workd like a thermometer. Our work demonstrates a new and simple method to measure heat diffusion in a well-defined geometry, and it is especially suitable for use in a hot corrosive system because it is a noncontact method.

  18. Systems and methods for generation of hydrogen peroxide vapor

    DOEpatents

    Love, Adam H; Eckels, Joel Del; Vu, Alexander K; Alcaraz, Armando; Reynolds, John G

    2014-12-02

    A system according to one embodiment includes a moisture trap for drying air; at least one of a first container and a second container; and a mechanism for at least one of: bubbling dried air from the moisture trap through a hydrogen peroxide solution in the first container for producing a hydrogen peroxide vapor, and passing dried air from the moisture trap into a headspace above a hydrogen peroxide solution in the second container for producing a hydrogen peroxide vapor. A method according one embodiment includes at least one of bubbling dried air through a hydrogen peroxide solution in a container for producing a first hydrogen peroxide vapor, and passing dried air from the moisture trap into a headspace above the hydrogen peroxide solution in a container for producing a second hydrogen peroxide vapor. Additional systems and methods are also presented.

  19. Laser vaporization of cirrus-like ice particles with secondary ice multiplication

    PubMed Central

    Matthews, Mary; Pomel, François; Wender, Christiane; Kiselev, Alexei; Duft, Denis; Kasparian, Jérôme; Wolf, Jean-Pierre; Leisner, Thomas

    2016-01-01

    We investigate the interaction of ultrashort laser filaments with individual 90-μm ice particles, representative of cirrus particles. The ice particles fragment under laser illumination. By monitoring the evolution of the corresponding ice/vapor system at up to 140,000 frames per second over 30 ms, we conclude that a shockwave vaporization supersaturates the neighboring region relative to ice, allowing the nucleation and growth of new ice particles, supported by laser-induced plasma photochemistry. This process constitutes the first direct observation of filament-induced secondary ice multiplication, a process that strongly modifies the particle size distribution and, thus, the albedo of typical cirrus clouds. PMID:27386537

  20. Laser vaporization of cirrus-like ice particles with secondary ice multiplication.

    PubMed

    Matthews, Mary; Pomel, François; Wender, Christiane; Kiselev, Alexei; Duft, Denis; Kasparian, Jérôme; Wolf, Jean-Pierre; Leisner, Thomas

    2016-05-01

    We investigate the interaction of ultrashort laser filaments with individual 90-μm ice particles, representative of cirrus particles. The ice particles fragment under laser illumination. By monitoring the evolution of the corresponding ice/vapor system at up to 140,000 frames per second over 30 ms, we conclude that a shockwave vaporization supersaturates the neighboring region relative to ice, allowing the nucleation and growth of new ice particles, supported by laser-induced plasma photochemistry. This process constitutes the first direct observation of filament-induced secondary ice multiplication, a process that strongly modifies the particle size distribution and, thus, the albedo of typical cirrus clouds.

  1. A Linearly-Polarized Cesium Vapor Laser with Fundamental Mode Output and Low Threshold

    NASA Astrophysics Data System (ADS)

    Li, Zhi-Yong; Tan, Rong-Qing; Huang, Wei; Xu, Cheng

    2014-04-01

    We report a cesium vapor laser with fundamental mode output and a wavelength of 894 nm. The laser is pumped by a laser diode array with an external cavity of a holographic grating by using Littrow's structure. A slope efficiency of 22.4% is obtained by using a pumping source with a linewidth of 0.26 nm and 80 kPa methane as the buffer gas. The threshold pumping power is 1.56 W.

  2. Space Debris-de-Orbiting by Vaporization Impulse using Short Pulse Laser

    SciTech Connect

    Early, J; Bibeau, C; Claude, P

    2003-09-16

    Space debris constitutes a significant hazard to low earth orbit satellites and particularly to manned spacecraft. A quite small velocity decrease from vaporization impulses is enough to lower the perigee of the debris sufficiently for atmospheric drag to de-orbit the debris. A short pulse (picosecond) laser version of the Orion concept can accomplish this task in several years of operation. The ''Mercury'' short pulse Yb:S-FAP laser being developed at LLNL for laser fusion is appropriate for this task.

  3. Integrated Rig for the Production of Boron Nitride Nanotubes via the Pressurized Vapor-Condenser Method

    NASA Technical Reports Server (NTRS)

    Smith, Michael W. (Inventor); Jordan, Kevin C. (Inventor)

    2014-01-01

    An integrated production apparatus for production of boron nitride nanotubes via the pressure vapor-condenser method. The apparatus comprises: a pressurized reaction chamber containing a continuously fed boron containing target having a boron target tip, a source of pressurized nitrogen and a moving belt condenser apparatus; a hutch chamber proximate the pressurized reaction chamber containing a target feed system and a laser beam and optics.

  4. Integrated rig for the production of boron nitride nanotubes via the pressurized vapor-condenser method

    DOEpatents

    Smith, Michael W; Jordan, Kevin C

    2014-03-25

    An integrated production apparatus for production of boron nitride nanotubes via the pressure vapor-condenser method. The apparatus comprises: a pressurized reaction chamber containing a continuously fed boron containing target having a boron target tip, a source of pressurized nitrogen and a moving belt condenser apparatus; a hutch chamber proximate the pressurized reaction chamber containing a target feed system and a laser beam and optics.

  5. Method and apparatus for precision laser micromachining

    DOEpatents

    Chang, Jim; Warner, Bruce E.; Dragon, Ernest P.

    2000-05-02

    A method and apparatus for micromachining and microdrilling which results in a machined part of superior surface quality is provided. The system uses a near diffraction limited, high repetition rate, short pulse length, visible wavelength laser. The laser is combined with a high speed precision tilting mirror and suitable beam shaping optics, thus allowing a large amount of energy to be accurately positioned and scanned on the workpiece. As a result of this system, complicated, high resolution machining patterns can be achieved. A cover plate may be temporarily attached to the workpiece. Then as the workpiece material is vaporized during the machining process, the vapors condense on the cover plate rather than the surface of the workpiece. In order to eliminate cutting rate variations as the cutting direction is varied, a randomly polarized laser beam is utilized. A rotating half-wave plate is used to achieve the random polarization. In order to correctly locate the focus at the desired location within the workpiece, the position of the focus is first determined by monitoring the speckle size while varying the distance between the workpiece and the focussing optics. When the speckle size reaches a maximum, the focus is located at the first surface of the workpiece. After the location of the focus has been determined, it is repositioned to the desired location within the workpiece, thus optimizing the quality of the machined area.

  6. Optoacoustic measurements of water vapor absorption at selected CO laser wavelengths in the 5-micron region

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

    Measurements of water vapor absorption were taken with a resonant optoacoustical detector (cylindrical pyrex detector, two BaF2 windows fitted into end plates at slight tilt to suppress Fabry-Perot resonances), for lack of confidence in existing spectral tabular data for the 5-7 micron region, as line shapes in the wing regions of water vapor lines are difficult to characterize. The measurements are required for air pollution studies using a CO laser, to find the differential absorption at the wavelengths in question due to atmospheric constituents other than water vapor. The design and performance of the optoacoustical detector are presented. Effects of absorption by ambient NO are considered, and the fixed-frequency discretely tunable CO laser is found suitable for monitoring urban NO concentrations in a fairly dry climate, using the water vapor absorption data obtained in the study.

  7. Computer modeling of the sensitivity of a laser water vapor sensor to variations in temperature and air speed

    NASA Technical Reports Server (NTRS)

    Tucker, George F.

    1994-01-01

    Currently, there is disagreement among existing methods of determining atmospheric water vapor concentration at dew-points below -40 C. A major source of error is wall effects which result from the necessity of bringing samples into the instruments. All of these instruments also have response times on the order of seconds. NASA Langley is developing a water vapor sensor which utilizes the absorption of the infrared radiation produced by a diode laser to estimate water vapor concentration. The laser beam is directed through an aircraft window to a retroreflector located on an engine. The reflected beam is detected by an infrared detector located near the laser. To maximize signal to noise, derivative signals are analyzed. By measuring the 2f/DC signal and correcting for ambient temperature, atmospheric pressure and air speed (which results in a Doppler shifting of the laser beam), the water vapor concentration can be retrieved. Since this is an in situ measurement there are no wall effects and measurements can be made at a rate of more than 20 per second. This allows small spatial variations of water vapor to be studied. In order to study the sensitivity of the instrument to variations in temperature and air speed, a computer program which generated the 2f, 3f, 4f, DC and 2f/DC signals of the instrument as a function of temperature, pressure and air speed was written. This model was used to determine the effect of errors in measurement of the temperature and air speed on the measured water vapor concentration. Future studies will quantify the effect of pressure measurement errors, which are expected to be very small. As a result of these studied, a retrieval algorithm has been formulated, and will be applied to data taken during the PEM-West atmospheric science field mission. Spectroscopic studies of the water vapor line used by the instrument will be used to refine this algorithm. To prepare for these studies, several lasers have been studied to determine their

  8. [The use of laser vaporization for the treatment of benign prostatic hyperplasia].

    PubMed

    Ustinov, D V; Kholtobin, D P; Kul'chavenia, E V; Aĭzikovich, B I

    2013-01-01

    Results of use of UroBeam laser diode in 72 patients with benign prostatic hyperplasia (BPH) were analyzed. Average prostate volume was 67.29 +/- 26.72 cm3, the duration of vaporization--69.2 +/- 23.7 min. Blood loss was minimal. In the period from 2 weeks to 4 months after surgery, 9 patients have developed acute urinary retention. In the early postoperative period, acute prostatitis was diagnosed in 7 patients and was jugulated using drug treatment. The laser vaporization of BPH led to a three-fold reduction in the severity of urinary disorders and increase the urinary flow rate. The combination of laser vaporization of the prostate with transurethral resection of the prostate allow to improve the recovery of urination after surgery.

  9. Modeling of a diode four-side pumped cesium vapor laser amplifier with flowing medium

    NASA Astrophysics Data System (ADS)

    Xia, Chunsheng; Shen, Binglin; Xu, Xingqi; Pan, Bailiang

    2017-03-01

    A physical model for a flowing four-side pumped alkali vapor laser MOPA system, which considers the saturation effect and amplified spontaneous emission (ASE) and cross-sectional temperature distribution, is established to simulate the output performance of the cesium vapor amplifier. According to the experimental parameters, the simulated result agrees well with the experiment, which demonstrates the validity of this model. Influences of the seed power, the flowing velocity, and the cell length on the amplified power are simulated and analyzed, and a set of optimal operating parameters are obtained. Thus, the model can provide an effective way for designing an efficient side-pumped flowing-gas alkali vapor amplifier.

  10. Development of Field-deployable Diode-laser-based Water Vapor Dial

    NASA Astrophysics Data System (ADS)

    Pham Le Hoai, Phong; Abo, Makoto; Sakai, Tetsu

    2016-06-01

    In this paper, a field-deployable diode-laser-based differential absorption lidar (DIAL) has been developed for lower-tropospheric water vapor observation in Tokyo, Japan. A photoacoustic cell is used for spectroscopy experiment around absorption peaks of 829.022 nm and 829.054 nm. The water vapor density extracted from the observational data agrees with the referenced radiosonde data. Furthermore, we applied modulated pulse technique for DIAL transmitter. It enables DIAL to measure water vapor profile for both low and high altitude regions.

  11. Nano structured physical vapor deposited coatings by means of picosecond laser radiation.

    PubMed

    Bobzin, K; Bagcivan, N; Ewering, M; Gillner, A; Beckemper, S; Hartmann, C; Theiss, S

    2011-10-01

    Molding of nano structures by injection molding leads to special requirements for the tools e.g., wear resistance and as low as possible release forces of the molded components. On the other hand it is not allowed to affect the replication precision. Physical vapor deposition is one of the promising technologies for applying coatings with adapted properties like high hardness, low roughness, low Young's modulus and less adhesion to the plastics melt. Although physical vapor deposition technology allows the deposition of films on micro structures without changing the structure significantly, film deposition on nano structures and small micro structures leads to a relevant change in surface topography. For this reason direct structuring of physical vapor deposition coatings might be beneficial. In this paper structuring was done using a picoseconds ultraviolet laser, Lumera Laser "Rapid," with a master oscillator power amplifier system at 355 nm. Two different coatings were deposited by magnetron sputter ion plating physical vapor deposition technology for laser structuring tests ((Cr, Al)N, (Cr, Al,Si)N). After deposition, the coatings were analyzed by common techniques regarding hardness, Young's modulus and morphology. The structures were analyzed by scanning electron microscopy. The results show a high potential for laser structuring of coatings deposited via physical vapor deposition. Linear structures with sizes between 400 nm and 10microm were realized.

  12. Containerless laser-induced flourescence study of vaporization and optical properties for sapphire and alumina

    NASA Technical Reports Server (NTRS)

    Nordine, Paul C.; Schiffman, Robert A.

    1988-01-01

    Evaporation of aluminum oxide was studied from 1800 to 2327 K by laser-induced flourescence (LIF) detection of Al atom vapor over sapphire and alumina spheres that were levitated in an argon gas jet and heated with a continuous wave CO2 laser. Optical properties were determined from apparent specimen temperatures measured with an optical pyrometer and true temperatures deduced from the LIF intensity versus temperature measurements using the known temperature dependence of the Al atom vapor concentration in equilibrium with Al2O3. The effects of impurities and dissolved oxygen on the high-temperature optical properties of aluminum oxide were discussed.

  13. High-energy transversely pumped alkali vapor laser

    NASA Astrophysics Data System (ADS)

    Zweiback, J.; Komashko, A.

    2011-03-01

    We report on the results from our transversely pumped alkali laser. This system uses an Alexandrite laser to pump a stainless steel laser head. The system uses methane and helium as buffer gasses. Using rubidium, the system produced up to 40 mJ of output energy when pumped with 63 mJ. Slope efficiency was 75%. Using potassium as the lasing species the system produced 32 mJ and a 53% slope efficiency.

  14. Characterization and reactivity of Pd Pt bimetallic supported catalysts obtained by laser vaporization of bulk alloy

    NASA Astrophysics Data System (ADS)

    Rousset, J. L.; Cadete Santos Aires, F. J.; Bornette, F.; Cattenot, M.; Pellarin, M.; Stievano, L.; Renouprez, A. J.

    2000-09-01

    Bimetallic Pd-Pt clusters produced by laser vaporization of bulk alloy have been deposited on high surface alumina. Energy dispersive X-ray (EDX) analysis and transmission electron microscopy (TEM) show that they have a perfectly well-defined stoichiometry and a narrow range of size. Therefore, they constitute ideal systems to investigate alloying effects towards reactivity. Pd-Pt alloys are already known for their applications in the hydrogenation of unsaturated hydrocarbons, especially aromatics, because this system is highly resistant to sulfur and nitrogen poisoning. In this context, the catalytic properties of this system have been investigated in the hydrogenation of tetralin in the presence of hydrogen sulfide. Preliminary results show that this model catalyst is more sulfur-resistant than each of the pure supported metals prepared by chemical methods.

  15. Ex vivo evaluation of safety and efficacy of vaporization of the prostate using a 300 W high-power laser diode with the wavelength of 980 nm

    NASA Astrophysics Data System (ADS)

    Takada, Junya; Honda, Norihiro; Hazama, Hisanao; Awazu, Kunio

    2014-03-01

    Laser vaporization of the prostate is one of the promising technique for less-invasive treatment of benign prostatic hyperplasia. However, shorter operative duration and higher hemostatic ability are expected. The wavelength of 980 nm offers a high simultaneous absorption by water and hemoglobin, so that it combines the efficient vaporization with good hemostasis. Therefore, we have evaluated the safety and efficacy of vaporization of the prostate using a recently developed 300 W high-power laser diode with the wavelength of 980 nm. First, validity of bovine prostate tissue as the sample was confirmed by measuring the optical properties of bovine and human prostate tissue using a double integrating sphere optical system. Next, contact and non-contact ex vivo irradiations were performed for various irradiation powers and times, and vaporized and coagulated depths were measured. In the contact irradiation, the vaporized depth at the power of 300 W was significantly deeper than that at the power of 100 W, while the difference was relatively smaller for the coagulated depths at 300 and 100 W. In the non-contact irradiation, coagulation as thick as that in the contact irradiation was observed almost without vaporization. Therefore, it is suggested that the treatment in the contact irradiation using the high-power laser diode can vaporize the prostate more efficiently without increasing the risk of perforation. Hemostasis with the coagulation would be possible in both irradiation methods. To prevent the postoperative perforation, operators need to understand the relationship between the coagulated depth and the irradiation conditions.

  16. Scalable Production Method for Graphene Oxide Water Vapor Separation Membranes

    SciTech Connect

    Fifield, Leonard S.; Shin, Yongsoon; Liu, Wei; Gotthold, David W.

    2016-01-01

    ABSTRACT

    Membranes for selective water vapor separation were assembled from graphene oxide suspension using techniques compatible with high volume industrial production. The large-diameter graphene oxide flake suspensions were synthesized from graphite materials via relatively efficient chemical oxidation steps with attention paid to maintaining flake size and achieving high graphene oxide concentrations. Graphene oxide membranes produced using scalable casting methods exhibited water vapor flux and water/nitrogen selectivity performance meeting or exceeding that of membranes produced using vacuum-assisted laboratory techniques. (PNNL-SA-117497)

  17. A Level Set Method for vaporizing two-phase flows

    NASA Astrophysics Data System (ADS)

    Tanguy, Sébastien; Ménard, Thibaut; Berlemont, Alain

    2007-02-01

    Development and applications of numerical methods devoted to reactive interface simulations are presented. Emphasis is put on vaporization, where numerical difficulties arise in imposing accurate jump conditions for heat and mass transfers. We use both the Level Set Method and the Ghost Fluid Method to capture the interface motion accurately and to handle suitable jump conditions. A local vaporization mass flow rate per unit of surface area is defined and Stefan flow is involved in the process. Specific care has been devoted to the extension of discontinuous variables across the interface to populate ghost cells, in order to avoid parasitic currents and numerical diffusion across the interface. A projection method is set up to impose both the velocity field continuity and a divergence-free condition for the extended velocity field across the interface. The d2 law is verified in the numerical simulations of the vaporization of an isolated static drop. Results are then presented for a water droplet moving in air. Vapor mass fraction and temperature fields inside and outside the droplet are presented.

  18. Radial distribution of radiation in a CuBr vapor brightness amplifier used in laser monitors

    NASA Astrophysics Data System (ADS)

    Gubarev, F. A.; Trigub, M. V.; Klenovskii, M. S.; Li, Lin; Evtushenko, G. S.

    2016-01-01

    The paper presents a study of the effect of excitation conditions in a CuBr vapor brightness amplifier in a monostatic laser monitor on the radial non-uniformity of the radiation bearing the information about the object being visualized. A significant dependence of radial signal distribution on the concentrations of CuBr, HBr and pumping power has been demonstrated. In particular, an increase in CuBr vapor concentration causes the gain profile of the active medium to constrict and the axial gain to increase. The conditions for the most uniform radial distribution of the laser monitor signal are substantially different from those for the maximum radiated power. The paper demonstrates HBr doping to be usable as a tool to correct the non-uniformity of the radial distribution of laser monitor radiation. An addition of ~0.15 Torr HBr broadens and flattens the radiation profile, improving an important aspect of laser monitor image quality.

  19. Diode Pumped Alkali Vapor Lasers - A New Pathway to High Beam Quality at High Average Power

    SciTech Connect

    Page, R H; Boley, C D; Rubenchik, A M; Beach, R J

    2005-05-06

    Resonance-transition alkali-vapor lasers have only recently been demonstrated [1] but are already attracting considerable attention. Alkali-atom-vapor gain media are among the simplest possible systems known, so there is much laboratory data upon which to base performance predictions. Therefore, accurate modeling is possible, as shown by the zero- free-parameter fits [2] to experimental data on alkali-vapor lasers pumped with Ti:sapphire lasers. The practical advantages of two of the alkali systems--Rb and Cs--are enormous, since they are amenable to diode-pumping [3,4]. Even without circulating the gas mixture, these lasers can have adequate cooling built-in owing to the presence of He in their vapor cells. The high predicted (up to 70%) optical-to-optical efficiency of the alkali laser, the superb (potentially 70% or better) wall-plug efficiency of the diode pumps, and the ability to exhaust heat at high temperature (100 C) combine to give a power-scalable architecture that is lightweight. A recent design exercise [5] at LLNL estimated that the system ''weight-to-power ratio'' figure of merit could be on the order of 7 kg/kW, an unprecedented value for a laser of the 100 kW class. Beam quality is expected to be excellent, owing to the small dn/dT value of the gain medium. There is obviously a long way to go, to get from a small laser pumped with a Ti:sapphire or injection-seeded diode system (of near-perfect beam quality, and narrow linewidth) [1, 4] to a large system pumped with broadband, multimode diode- laser arrays. We have a vision for this technology-development program, and have already built diode-array-pumped Rb lasers at the 1 Watt level. A setup for demonstrating Diode-array-Pumped Alkali vapor Lasers (DPALs) is shown in Figure 1. In general, use of a highly-multimode, broadband pump source renders diode-array-based experiments much more difficult than the previous ones done with Ti:sapphire pumping. High-NA optics, short focal distances, and short

  20. High-speed off-axis holographic cinematography with a copper-vapor-pumped dye laser.

    PubMed

    Lauterborn, W; Judt, A; Schmitz, E

    1993-01-01

    A series of coherent light pulses is generated by pumping a dye laser with the pulsed output of a copper-vapor laser at rates of as much as 20 kHz. Holograms are recorded at this pulse rate on a rotating holographic plate. This technique of high-speed holographic cinematography is demonstrated by viewing the bubble filaments that appear in water under the action of a sound field of high intensity.

  1. Spectral control of an alexandrite laser for an airborne water-vapor differential absorption lidar system

    NASA Technical Reports Server (NTRS)

    Ponsardin, Patrick; Grossmann, Benoist E.; Browell, Edward V.

    1994-01-01

    A narrow-linewidth pulsed alexandrite laser has been greatly modified for improved spectral stability in an aircraft environment, and its operation has been evaluated in the laboratory for making water-vapor differential absorption lidar measurements. An alignment technique is described to achieve the optimum free spectral range ratio for the two etalons inserted in the alexandrite laser cavity, and the sensitivity of this ratio is analyzed. This technique drastically decreases the occurrence of mode hopping, which is commonly observed in a tunable, two-intracavity-etalon laser system. High spectral purity (greater than 99.85%) at 730 nm is demonstrated by the use of a water-vapor absorption line as a notch filter. The effective cross sections of 760-nm oxygen and 730-nm water-vapor absorption lines are measured at different pressures by using this laser, which has a finite linewidth of 0.02 cm(exp -1) (FWHM). It is found that for water-vapor absorption linewidths greater than 0.04 cm(exp -1) (HWHM), or for altitudes below 10 km, the laser line can be considered monochromatic because the measured effective absorption cross section is within 1% of the calculated monochromatic cross section. An analysis of the environmental sensitivity of the two intracavity etalons is presented, and a closed-loop computer control for active stabilization of the two intracavity etalons in the alexandrite laser is described. Using a water-vapor absorption line as a wavelength reference, we measure a long-term frequency drift (approximately 1.5 h) of less than 0.7 pm in the laboratory.

  2. Ablation of biological tissues by radiation of strontium vapor laser

    SciTech Connect

    Soldatov, A. N. Vasilieva, A. V.

    2015-11-17

    A two-stage laser system consisting of a master oscillator and a power amplifier based on sources of self- contained transitions in pairs SrI and SrII has been developed. The radiation spectrum contains 8 laser lines generating in the range of 1 – 6.45 μm, with a generation pulse length of 50 – 150 ns, and pulse energy of ∼ 2.5 mJ. The divergence of the output beam was close to the diffraction and did not exceed 0.5 mrad. The control range of the laser pulse repetition rate varied from 10 to 15 000 Hz. The given laser system has allowed to perform ablation of bone tissue samples without visible thermal damage.

  3. Detection and measurement of middle-distillate fuel vapors by use of tunable diode lasers.

    PubMed

    McNesby, K L; Wainner, R T; Daniel, R G; Skaggs, R R; Morris, J B; Miziolek, A W; Jackson, W M; McLaren, I A

    2001-02-20

    A sensor for the rapid (10-ms response time) measurement of vapors from the hydrocarbon-based fuels JP-8, DF-2, and gasoline is described. The sensor is based on a previously reported laser-mixing technique that uses two tunable diode lasers emitting in the near-infrared spectral region [Appl. Opt. 39, 5006 (2000)] to measure concentrations of gases that have unstructured absorption spectra. The fiber-mixed laser beam consists of two wavelengths: one that is absorbed by the fuel vapor and one that is not absorbed. Sinusoidally modulating the power of the two lasers at the same frequency but 180 degrees out of phase allows a sinusoidal signal to be generated at the detector (when the target gas is present in the line of sight). The signal amplitude, measured by use of standard phase-sensitive detection techniques, is proportional to the fuel-vapor concentration. Limits of detection at room temperature are reported for the vapors of the three fuels studied. Improvements to be incorporated into the next generation of the sensor are discussed.

  4. Power enhancement of a Rubidium vapor laser with a master oscillator power amplifier.

    PubMed

    Hostutler, David A; Klennert, Wade L

    2008-05-26

    A master oscillator power amplifier (MOPA) with variable amplifier gain lengths was built to demonstrate power enhancement of an alkali vapor laser. A small signal gain of 0.91 / cm for two different gain lengths was observed. For a 2 cm long amplifier gain length an amplification of 7.9 dB was observed.

  5. Spectrophone Measurement of the Water Vapor Continuum at DF Laser Frequencies

    DTIC Science & Technology

    1975-08-01

    afA’afthar^re^ enc " ^^ ^ ^ ^’ ’^ ™ ^ity The water vapor absorption for the DF laser frequencies consists of three components - selective absorption...Rome Air Development Center. (AD 778949) (RADC-TR-74-89) Bell, A.G., Proc. Am. Assoc. Advanced Scie . 29_, (1880), p. 115. Bell, A.G., Phil

  6. Role of zinc coating at liquid-vapor interface during laser material processing of zinc coated steel

    NASA Astrophysics Data System (ADS)

    Hwan Lee, Seung; Mazumder, Jyoti

    2013-07-01

    In laser material processing, one of the major interests is characterizing interfacial phenomena induced by thermal phase changes of materials. The interfacial characteristics in the laser processing of multi-coated materials show different behaviors compared to those of single material processing. The difference in thermo-physical properties of the coated and primary materials induces the contrasting characteristics of multiple interfacial phenomena including temperature, recoil pressure, capillary force, and thermo capillary force. The influence of coating layer to the interfacial physics evolutions is difficult to be modeled mathematically when the laser beam penetrates the multi-coated material layer by layer. This paper addresses the role of the zinc coating at the liquid-vapor interface during the laser processing of zinc coated steel, as a representative case of multi-coated materials. Computational modules incorporating the zinc layers were established and selectively applied at the locations where the zinc coatings exist to investigate the interfacial phenomena. The level set method was integrated with the modules to track the evolution of the liquid-vapor interface in a self-consistent manner. The interfacial phenomena characteristics were estimated by a 3D mathematical simulation study. A reflective topography method was employed to validate the mathematical model and to supplement our understandings of the interfacial evolution.

  7. Preparation of γ-Al2O3 films by laser chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Gao, Ming; Ito, Akihiko; Goto, Takashi

    2015-06-01

    γ- and α-Al2O3 films were prepared by chemical vapor deposition using CO2, Nd:YAG, and InGaAs lasers to investigate the effects of varying the laser wavelength and deposition conditions on the phase composition and microstructure. The CO2 laser was found to mostly produce α-Al2O3 films, whereas the Nd:YAG and InGaAs lasers produced γ-Al2O3 films when used at a high total pressure. γ-Al2O3 films had a cauliflower-like structure, while the α-Al2O3 films had a dense and columnar structure. Of the three lasers, it was the Nd:YAG laser that interacted most with intermediate gas species. This promoted γ-Al2O3 nucleation in the gas phase at high total pressure, which explains the cauliflower-like structure of nanoparticles observed.

  8. Water vapor concentration measurement in singlet oxygen generator by using emission spectroscopy method and absorption at 1392nm

    NASA Astrophysics Data System (ADS)

    Zhao, Weili; Wang, Zengqiang; Fang, Benjie; Li, Qingwei; Jin, Yuqi; Sang, Fengting

    2005-12-01

    By using emission spectroscopy method and absorption at 1392nm, partial water pressure at the exit of a square pipe-array jet-type singlet oxygen generator (SPJSOG) for chemical oxygen-iodine laser (COIL) was measured. The water vapor fraction was calculated from the partial water pressure in the diagnostic cell when we assumed the water vapor fraction in the diagnostic cell is the same as that in the generator. The results from the two methods showed that the water vapor concentration is less than 0.08 in this SPJSOG during normal operation. The water vapor fraction decreases with the increasing of the pressure in the generator and rises with the increasing of buffer gas flow rate and the basic hydrogen peroxide (BHP) temperature in the case of constant chlorine flow rate. Measurements showed that the change of water vapor fraction due to BHP temperature could be ignored during normal operation. It is indicated that the gas flow velocity is the main reason that affects on the water vapor fraction in COIL. It is proved that the emission spectroscopy method is one of the simple and convenient ways to measure the water vapor concentration in singlet oxygen generator (SOG), especially in real time measurements. But absorption spectroscopy method, as a direct measurement, can give the more factual results of the water concentration.

  9. Laser beam pulse formatting method

    DOEpatents

    Daly, Thomas P.; Moses, Edward I.; Patterson, Ralph W.; Sawicki, Richard H.

    1994-01-01

    A method for formatting a laser beam pulse (20) using one or more delay loops (10). The delay loops (10) have a partially reflective beam splitter (12) and a plurality of highly reflective mirrors (14) arranged such that the laser beam pulse (20) enters into the delay loop (10) through the beam splitter (12) and circulates therein along a delay loop length (24) defined by the mirrors (14). As the laser beam pulse (20) circulates within the delay loop (10) a portion thereof is emitted upon each completed circuit when the laser beam pulse (20) strikes the beam splitter (12). The laser beam pulse (20) is thereby formatted into a plurality of sub-pulses (50, 52, 54 and 56). The delay loops (10) are used in combination to produce complex waveforms by combining the sub-pulses (50, 52, 54 and 56) using additive waveform synthesis.

  10. A tunable MWIR laser remote sensor for chemical vapor detection

    NASA Astrophysics Data System (ADS)

    Bunn, Thomas L.; Noblett, Patricia M.; Otting, William D.

    1998-01-01

    The Air Force vision for Global Virtual Presence suggests a need for active remote sensing systems that provide both global coverage and the ability to detect multiple gaseous chemical species at low concentration from a significant standoff distance. The system will need to have acceptable weight, volume, and power characteristics, as well as a long operating lifetime for integration with various surveillance platforms. Laser based remote sensing systems utilizing the differential absorption lidar (DIAL) technique are promising for long range chemical sensing applications. Recent advancements in pulsed, diode pumped solid state laser (DPSSL) technology and in tunable optical parametric oscillators (OPO) make broadly tunable laser transmitters possible for the DIAL system. Also the characteristic narrow spectral bandwidth of these laser devices provides high measurement sensitivity and spectral selectivity with the potential to avoid interfering species. Rocketdyne has built and tested a tunable, midwave infrared (MWIR) DIAL system using DPSSL/OPO technology. The key to the system is a novel tuning and line narrowing technology developed for the OPO. The tuning system can quickly adjust to the desired wavelength and precisely locate a narrow spectral feature of interest. Once the spectral feature is located, a rapid dither tuning technique is employed. The laser pulses are tuned ``on'' and ``off'' the spectral resonance of a molecule with precise and repeatable performance as required to make the DIAL measurement. To date, the breadboard system has been tested by measuring methane, ethane, and sulfur dioxide in a calibrated gas cell at a range of 60 meters.

  11. A new mass spectrometer system for investigating laser-induced vaporization phenomena

    NASA Technical Reports Server (NTRS)

    Lincoln, K. A.

    1974-01-01

    A laser has been combined with a mass spectrometer in a new configuration developed for studies of high-temperature materials. A vacuum-lock, solid-sample inlet is mounted at one end of a cylindrical, high-vacuum chamber one meter in length with a nude ion-source, time-of-flight mass spectrometer at the opposite end. The samples are positioned along the axis of the chamber at distances up to one meter from the ion source, and their surfaces are vaporized by a pulsed laser beam entering via windows on one side of the chamber. The instrumentation along with its capabilities is described, and results from laser-induced vaporization of several graphites are presented.

  12. Infectious papillomavirus in the vapor of warts treated with carbon dioxide laser or electrocoagulation: Detection and protection

    SciTech Connect

    Sawchuk, W.S.; Weber, P.J.; Lowy, D.R.; Dzubow, L.M.

    1989-07-01

    Papillomavirus DNA has been reported recently in the vapor (smoke plume) derived from warts treated with carbon dioxide laser; this raises concerns for operator safety. We therefore have studied a group of human and bovine warts to define further the potential risk of wart therapy and to test whether a surgical mask could reduce exposure. Half of each wart was treated with carbon dioxide laser and the other half with electrocoagulation. The vapor produced by each form of therapy was collected with a dry filter vacuum apparatus and analyzed for the presence of papillomavirus. Vapor from human plantar warts was analyzed for the presence of human papillomavirus DNA, because there is no infectivity assay for human papillomavirus. Of plantar warts treated, five of eight laser-derived vapors and four of seven electrocoagulation-derived vapors were positive for human papillomavirus DNA. Greater amounts of papillomavirus DNA were usually recovered in the laser vapor than in the electrocoagulation vapor from the same wart. Bioassay readily detected infectious bovine papillomavirus in the vapor from bovine warts treated with either modality; more virus was present in laser-derived material. A surgical mask was found capable of removing virtually all laser- or electrocoagulation-derived virus, strongly suggesting that such masks can protect operators from potential inhalation exposure to papillomavirus.

  13. Method for producing laser targets

    DOEpatents

    Jarboe, Thomas R.; Baker, William R.

    1977-01-01

    An apparatus and method for producing deuterium targets or pellets of 25.mu. to 75.mu. diameter. The pellets are sliced from a continuously spun solid deuterium thread at a rate of up to 10 pellets/second. The pellets after being sliced from the continuous thread of deuterium are collimated and directed to a point of use, such as a laser activated combustion or explosion chamber wherein the pellets are imploded by laser energy or laser produced target plasmas for neutral beam injection.

  14. An automated dynamic water vapor permeation test method

    NASA Astrophysics Data System (ADS)

    Gibson, Phillip; Kendrick, Cyrus; Rivin, Donald; Charmchii, Majid; Sicuranza, Linda

    1995-05-01

    This report describes an automated apparatus developed to measure the transport of water vapor through materials under a variety of conditions. The apparatus is more convenient to use than the traditional test methods for textiles and clothing materials, and allows one to use a wider variety of test conditions to investigate the concentration-dependent and nonlinear transport behavior of many of the semipermeable membrane laminates which are now available. The dynamic moisture permeation cell (DMPC) has been automated to permit multiple setpoint testing under computer control, and to facilitate investigation of transient phenomena. Results generated with the DMPC are in agreement with and of comparable accuracy to those from the ISO 11092 (sweating guarded hot plate) method of measuring water vapor permeability.

  15. Laser photoacoustic detection of the essential oil vapors of thyme, mint, and anise

    NASA Astrophysics Data System (ADS)

    El-Kahlout, A. M.; Al-Jourani, M. M.; Abu-Taha, M. I.; Laine, Derek C.

    1998-07-01

    Photoacoustic studies of the vapors of the essential oils of thyme, mint and anise have been made using a line-tunable waveguide CO2 laser in conjunction with a heat-pipe type of photoacoustic vapor sample cell operated over the temperature range 20 - 180 degree(s)C. Identifying spectral fingerprint features are found in the 9 - 10 micrometers spectral region for each of the three essential oils investigated. The principal features of the photoacoustic spectrum of each essential oil are associated with the dominant chemicals present i.e. thymol in thyme oil, menthol in mint and anethole in anise.

  16. Atomic vapor laser isotope separation of lead-210 isotope

    DOEpatents

    Scheibner, Karl F.; Haynam, Christopher A.; Johnson, Michael A.; Worden, Earl F.

    1999-01-01

    An isotopically selective laser process and apparatus for removal of Pb-210 from natural lead that involves a one-photon near-resonant, two-photon resonant excitation of one or more Rydberg levels, followed by field ionization and then electrostatic extraction. The wavelength to the near-resonant intermediate state is counter propagated with respect to the second wavelength required to populate the final Rydberg state. This scheme takes advantage of the large first excited state cross section, and only modest laser fluences are required. The non-resonant process helps to avoid two problems: first, stimulated Raman Gain due to the nearby F=3/2 hyperfine component of Pb-207 and, second, direct absorption of the first transition process light by Pb-207.

  17. Atomic vapor laser isotope separation of lead-210 isotope

    SciTech Connect

    Scheibner, K.F.; Haynam, C.A.; Johnson, M.A.; Worden, E.F.

    1999-08-31

    An isotopically selective laser process and apparatus for removal of Pb-210 from natural lead that involves a one-photon near-resonant, two-photon resonant excitation of one or more Rydberg levels, followed by field ionization and then electrostatic extraction. The wavelength to the near-resonant intermediate state is counter propagated with respect to the second wavelength required to populate the final Rydberg state. This scheme takes advantage of the large first excited state cross section, and only modest laser fluences are required. The non-resonant process helps to avoid two problems: first, stimulated Raman Gain due to the nearby F=3/2 hyperfine component of Pb-207 and, second, direct absorption of the first transition process light by Pb-207. 5 figs.

  18. Method and apparatus to measure vapor pressure in a flow system

    DOEpatents

    Grossman, Mark W.; Biblarz, Oscar

    1991-01-01

    The present invention is directed to a method for determining, by a condensation method, the vapor pressure of a material with a known vapor pressure versus temperature characteristic, in a flow system particularly in a mercury isotope enrichment process.

  19. Piston pump and method of reducing vapor lock

    SciTech Connect

    Phillips, B.A.; Harvey, M.N.

    2000-02-15

    A pump includes a housing defining a cavity, at least one bore, a bore inlet, and a bore outlet. The bore extends from the cavity to the outlet and the inlet communicates with the bore at a position between the cavity and the outlet. A crankshaft is mounted in supports and has an eccentric portion disposed in the cavity. The eccentric portion is coupled to a piston so that rotation of the crankshaft reciprocates the piston in the bore between a discharge position an intake position. The bore may be offset from an axis of rotation to reduce bending of the piston during crankshaft rotation. During assembly of the pump, separate parts of the housing can be connected together to facilitate installation of internal pumping components. Also disclosed is a method of reducing vapor lock by mixing vapor and liquid portions of a substance and introducing the mixture into a piston bore.

  20. Piston pump and method of reducing vapor lock

    SciTech Connect

    Phillips, Benjamin A.; Harvey, Michael N.

    2001-01-30

    A pump includes a housing defining a cavity, at least one bore, a bore inlet, and a bore outlet. The bore extends from the cavity to the outlet and the inlet communicates with the bore at a position between the cavity and the outlet. A crankshaft is mounted in supports and has an eccentric portion disposed in the cavity. The eccentric portion is coupled to a piston so that rotation of the crankshaft reciprocates the piston in the bore between a discharge position an intake position. The bore may be offset from an axis of rotation to reduce bending of the piston during crankshaft rotation. During assembly of the pump, separate parts of the housing can be connected together to facilitate installation of internal pumping components. Also disclosed is a method of reducing vapor lock by mixing vapor and liquid portions of a substance and introducing the mixture into a piston bore.

  1. Laser beam alignment apparatus and method

    DOEpatents

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

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

  2. Laser beam alignment apparatus and method

    DOEpatents

    Gruhn, Charles R.; Hammond, Robert B.

    1981-01-01

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

  3. Method of and apparatus for measuring vapor density

    DOEpatents

    Nelson, L.D.; Cerni, T.A.

    1989-10-17

    Apparatus and method are disclosed which determine the concentration of an individual component, such as water vapor, of a multi-component mixture, such as a gaseous mixture for cooling a nuclear reactor. A hygrometer apparatus includes an infrared source for producing a broadband infrared energy beam that includes a strong water vapor absorption band and a weak water vapor absorption region. The beam is chopped to select infrared pulses. A temporally first pulse has a wavelength in the weakly absorbing region, a temporally second pulse has a wavelength in the strong band and a temporally third pulse has a wavelength in the weakly absorbing region. A fourth reference pulse representing background radiation is interposed in such chopped pulses. An indium arsenide infrared sensor is responsive to the pulses for generating an output signal in proportion to an equation given in the patent where N1 is proportional to the transmission through the sample of the first signal, N4 is related to the background radiation, and [K2 (N2-N4) + K3 (N3-N4)] is the time-weighted average of the transmission through the sample of the second and third pulses applicable at the time of the second pulse, with the reference pulse N4 being subtracted in each case to render the ratio independent of variations in the background radiation. 11 figs.

  4. Method of and apparatus for measuring vapor density

    DOEpatents

    Nelson, Loren D.; Cerni, Todd A.

    1989-01-01

    Apparatus and method determine the concentration of an individual component, such as water vapor, of a multi-component mixture, such as a gaseous mixture for cooling a nuclear reactor. A hygrometer apparatus includes an infrared source for producing a broadband infrared energy beam that includes a strong water vapor absorption band and a weak water vapor absorption region. The beam is chopped to select infrared pulses. A temporally first pulse has a wavelength in the weakly absorbing region, a temporally second pulse has a wavelength in the strong band and a temporally third pulse has a wavlength in the weakly absorbing region. A fourth reference pulse representing background radiation is interposed in such chopped pulses. An indium arsenide infrared sensor is responsive to the pulses for generating an output signal in proportion to: ##EQU1## where N1 is proportional to the transmission through the sample of the first signal, N4 is related to the background radiation, and [K2 (N2-N4)+K3 (N3-N4)] is the time-weighted average of the transmission through the sample of the second and third pulses applicable at the time of the second pulse, with the reference pulse N4 being subtracted in each case to render the ratio independent of variations in the background radiation.

  5. Identification of vapor-phase chemical warfare agent simulants and rocket fuels using laser-induced breakdown spectroscopy

    SciTech Connect

    Stearns, Jaime A.; McElman, Sarah E.; Dodd, James A.

    2010-05-01

    Application of laser-induced breakdown spectroscopy (LIBS) to the identification of security threats is a growing area of research. This work presents LIBS spectra of vapor-phase chemical warfare agent simulants and typical rocket fuels. A large dataset of spectra was acquired using a variety of gas mixtures and background pressures and processed using partial least squares analysis. The five compounds studied were identified with a 99% success rate by the best method. The temporal behavior of the emission lines as a function of chamber pressure and gas mixture was also investigated, revealing some interesting trends that merit further study.

  6. Upper Tropospheric and Lower Stratospheric Measurements of Water Vapor by the JPL Laser Hygrometer Mark 2

    NASA Astrophysics Data System (ADS)

    Troy, R. F.

    2015-12-01

    The concentration of water vapor in the upper troposphere and lower stratosphere has a significant impact on climate. Over the last sixteen years, the JPL Laser Hygrometers have collected a significant data record of atmospheric humidity from several platforms, including the NASA ER-2, WB-57, DC-8, and Global Hawk. Here, we describe the observed relation between atmospheric humidity and temperature in-cloud and out of cloud near the tropopause. The relation between cloud microphysical properties and humidity is also explored. We feature measurements of water vapor from a substantially improved instrument, JPL Laser Hygrometer Mark 2, made during the 2013 NASA SEAC4RS (Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys) field mission.

  7. Kinetics of laser pulse vaporization of uranium dioxide by mass spectrometry

    SciTech Connect

    Tsai, C.

    1981-11-01

    Safety analyses of nuclear reactors require knowledge of the evaporation behavior of UO/sub 2/ at temperatures well above the melting point of 3140 K. In this study, rapid transient heating of a small spot on a UO/sub 2/ specimen was accomplished by a laser pulse, which generates a surface temperature excursion. This in turn vaporizes the target surface and the gas expands into vacuum. The surface temperature transient was monitored by a fast-response automatic optical pyrometer. The maximum surface temperatures investigated range from approx. 3700 K to approx. 4300 K. A computer program was developed to simulate the laser heating process and calculate the surface temperature evolution. The effect of the uncertainties of the high temperature material properties on the calculation was included in a sensitivity study for UO/sub 2/ vaporization. The measured surface temperatures were in satisfactory agreements.

  8. Dual-axis vapor cell for simultaneous laser frequency stabilization on disparate optical transitions

    SciTech Connect

    Jayakumar, Anupriya Plotkin-Swing, Benjamin; Jamison, Alan O.; Gupta, Subhadeep

    2015-07-15

    We have developed a dual-axis ytterbium (Yb) vapor cell and used it to simultaneously address the two laser cooling transitions in Yb at wavelengths 399 nm and 556 nm, featuring the disparate linewidths of 2π × 29 MHz and 2π × 182 KHz, respectively. By utilizing different optical paths for the two wavelengths, we simultaneously obtain comparable optical densities suitable for saturated absorption spectroscopy for both the transitions and keep both the lasers frequency stabilized over several hours. We demonstrate that by appropriate control of the cell temperature profile, two atomic transitions differing in relative strength across a large range of over three orders of magnitude can be simultaneously addressed, making the device adaptable to a variety of spectroscopic needs. We also show that our observations can be understood with a simple theoretical model of the Yb vapor.

  9. Optical emission spectroscopy of metal vapor dominated laser-arc hybrid welding plasma

    SciTech Connect

    Ribic, B.; DebRoy, T.; Burgardt, P.

    2011-04-15

    During laser-arc hybrid welding, plasma properties affect the welding process and the weld quality. However, hybrid welding plasmas have not been systematically studied. Here we examine electron temperatures, species densities, and electrical conductivity for laser, arc, and laser-arc hybrid welding using optical emission spectroscopy. The effects of arc currents and heat source separation distances were examined because these parameters significantly affect weld quality. Time-average plasma electron temperatures, electron and ion densities, electrical conductivity, and arc stability decrease with increasing heat source separation distance during hybrid welding. Heat source separation distance affects these properties more significantly than the arc current within the range of currents considered. Improved arc stability and higher electrical conductivity of the hybrid welding plasma result from increased heat flux, electron temperatures, electron density, and metal vapor concentrations relative to arc or laser welding.

  10. Laser vaporization and excisional techniques in the treatment of cervical intraepithelial neoplasia.

    PubMed

    Monaghan, J M

    1995-03-01

    The CO2 laser proved to be a vital tool in the development of conservative therapy for the treatment of CIN in the 1980s. In conjunction with colposcopy, the laser has allowed many women to achieve the security of identified and treated CIN with the freedom to live their lives normally, including the achievement of pregnancies. The laser may be used either in the ablative (vaporization) or the cutting mode. This flexibility allows patients with unsatisfactory as well as satisfactory colposcopy to be managed. The results of treatment are universally excellent, with clearance rates of 96% being reported. Complications are rare both in the short and long term, most patients returning fully to normal activities within 4 weeks of therapy. Although the laser is being superceded to some extent by the advent of the loop diathermy technique, it will for years to come represent a valuable and useful tool in the treatment of CIN.

  11. Numerical simulation of transient, incongruent vaporization induced by high power laser

    SciTech Connect

    Tsai, C.H.

    1981-01-01

    A mathematical model and numerical calculations were developed to solve the heat and mass transfer problems specifically for uranum oxide subject to laser irradiation. It can easily be modified for other heat sources or/and other materials. In the uranium-oxygen system, oxygen is the preferentially vaporizing component, and as a result of the finite mobility of oxygen in the solid, an oxygen deficiency is set up near the surface. Because of the bivariant behavior of uranium oxide, the heat transfer problem and the oxygen diffusion problem are coupled and a numerical method of simultaneously solving the two boundary value problems is studied. The temperature dependence of the thermal properties and oxygen diffusivity, as well as the highly ablative effect on the surface, leads to considerable non-linearities in both the governing differential equations and the boundary conditions. Based on the earlier work done in this laboratory by Olstad and Olander on Iron and on Zirconium hydride, the generality of the problem is expanded and the efficiency of the numerical scheme is improved. The finite difference method, along with some advanced numerical techniques, is found to be an efficient way to solve this problem.

  12. Power Enhancement of a Rubidium Vapor Laser With a Master Oscillator Power Amplifier (Postprint)

    DTIC Science & Technology

    2009-09-15

    Phys. Lett. 34, 655-658 (1979). 5 . W. F. Krupke, R. J. Beach, V. K. Kanz, and S. A. Payne, “Resonance transition 795-nm rubidium laser,” Opt. Lett...Kanz, and W. F. Krupke, “Multimode-diode-pumped gas (alkali-vapor) laser,” Opt. Lett. 31 , 353-355 (2006). 10. Y. Wang, T. Kasamatsu, Y.Zheng, H...OPTICS EXPRESS 8050 #94531 - $15.00 USD Received 7 Apr 2008; revised 4 May 2008; accepted 7 May 2008; published 19 May 2008 (DPAL) started rapidly gaining

  13. Imaging of droplets and vapor distributions in a diesel fuel spray by means of a laser absorption-scattering technique.

    PubMed

    Zhang, Y Y; Yoshizaki, T; Nishida, K

    2000-11-20

    The droplets and vapor distributions in a fuel spray were imaged by a dual-wavelength laser absorption-scattering technique. 1,3-dimethylnaphthalene, which has physical properties similar to those of Diesel fuel, strongly absorbs the ultraviolet light near the fourth harmonic (266 nm) of a Nd:YAG laser but is nearly transparent to the visible light near the second harmonic (532 nm) of a Nd:YAG laser. Therefore, droplets and vapor distributions in a Diesel spray can be visualized by an imaging system that uses a Nd:YAG laser as the incident light and 1,3-dimethylnaphthalene as the test fuel. For a quantitative application consideration, the absorption coefficients of dimethylnapthalene vapor at different temperatures and pressures were examined with an optical spectrometer. The findings of this study suggest that this imaging technique has great promise for simultaneously obtaining quantitative information of droplet density and vapor concentration in Diesel fuel spray.

  14. Synthesis of Cobalt Oxides Thin Films Fractal Structures by Laser Chemical Vapor Deposition

    PubMed Central

    Haniam, P.; Kunsombat, C.; Chiangga, S.; Songsasen, A.

    2014-01-01

    Thin films of cobalt oxides (CoO and Co3O4) fractal structures have been synthesized by using laser chemical vapor deposition at room temperature and atmospheric pressure. Various factors which affect the density and crystallization of cobalt oxides fractal shapes have been examined. We show that the fractal structures can be described by diffusion-limited aggregation model and discuss a new possibility to control the fractal structures. PMID:24672354

  15. Referred Air Method 25E: Determination of a Vapor Phase Organic Concentration in Waste Samples

    EPA Pesticide Factsheets

    This method is applicable for determining the vapor pressure of waste. The headspace vapor of the sample is analyzed for carbon content by a headspace analyzer, which uses a flame ionization detector (FID).

  16. Method and apparatus for producing thermal vapor stream

    DOEpatents

    Cradeur, Robert R.; Sperry, John S.; Krajicek, Richard W.

    1979-01-01

    Method and apparatus for producing a thermal vapor stream for injecting into a subterranean formation for the recovery of liquefiable minerals therefrom, including a pressure vessel containing a high pressure combustion chamber for producing a heating gas for introduction into a heating gas injector. The heating gas injector is partly immersed in a steam generating section of the pressure vessel such that the heating gas is passed through the steam generating section to produce steam and combustion products which are directed between the pressure vessel and the combustion chamber for simultaneously cooling of the combustion chamber by further heating of the steam and combustion gases.

  17. Different CO2 laser vaporization protocols for the therapy of oral precancerous lesions and precancerous conditions: a 10-year follow-up.

    PubMed

    Deppe, Herbert; Mücke, Thomas; Hohlweg-Majert, Bettina; Hauck, Wolfgang; Wagenpfeil, Stefan; Hölzle, Frank

    2012-01-01

    Use of the CO(2) laser (λ = 10.6 μm, continuous wave, defocused) is an established procedure for the treatment of premalignant lesions. Through employment of the sp-mode as well as scanners, thermal laser effects can be reduced but, on the other hand, a lesser degree of destruction of dysplastic cells could lead to an increased recurrence rate. The purpose of this study was to prospectively evaluate the recurrence rates resulting from different methods of CO(2) laser vaporization. From May 1995 to May, 2005, 145 patients with a total of 148 premalignant lesions of the oral mucosa were treated in a prospective clinical study. Sixty-two lesions in 62 patients were vaporized with the defocused CO(2) laser (group 1). In a further 45 lesions (43 patients, group 2), a scanner was additionally employed. In the remaining 41 lesions (40 patients, group 3), vaporization was carried out in the sp-mode in which the scanner was also used. In September, 2005, recurrence rates in the three groups were evaluated. Use of the scanner in sp-mode resulted in the most irregular tissue vaporization. This can be accounted for by the irregular paths of the laser beam and the pulsed delivery of the laser energy. Statistically significant lowest recurrence rates were yielded by the defocused cw-technique followed by the cw-scanner and the sp-mode. These results indicate that for CO(2) laser treatment of premalignant lesions of the oral mucosa, the best results can be achieved with the defocused technique. It may be assumed that other methods with lesser penetration of thermal effects (e.g. sp, scanner) do not reach the deeper-lying cells and, consequently, render higher rates of recurrence.

  18. Vaporization and recondensation dynamics of indocyanine green-loaded perfluoropentane droplets irradiated by a short pulse laser

    NASA Astrophysics Data System (ADS)

    Yu, Jaesok; Chen, Xucai; Villanueva, Flordeliza S.; Kim, Kang

    2016-12-01

    Phase-transition droplets have been proposed as promising contrast agents for ultrasound and photoacoustic imaging. Short pulse laser activated perfluorocarbon-based droplets, especially when in a medium with a temperature below their boiling point, undergo phase changes of vaporization and recondensation in response to pulsed laser irradiation. Here, we report and discuss the vaporization and recondensation dynamics of perfluoropentane droplets containing indocyanine green in response to a short pulsed laser with optical and acoustic measurements. To investigate the effect of temperature on the vaporization process, an imaging chamber was mounted on a temperature-controlled water reservoir and then the vaporization event was recorded at 5 million frames per second via a high-speed camera. The high-speed movies show that most of the droplets within the laser beam area expanded rapidly as soon as they were exposed to the laser pulse and immediately recondensed within 1-2 μs. The vaporization/recondensation process was consistently reproduced in six consecutive laser pulses to the same area. As the temperature of the media was increased above the boiling point of the perfluoropentane, the droplets were less likely to recondense and remained in a gas phase after the first vaporization. These observations will help to clarify the underlying processes and eventually guide the design of repeatable phase-transition droplets as a photoacoustic imaging contrast agent.

  19. Laser initiation and decay processes in an organic vapor plasma

    NASA Astrophysics Data System (ADS)

    Ding, Guowen

    A large volume organic molecular plasma (hundreds of cm3) is created by a 193 nm laser ionizing an organic molecule, Tetrakis-(dimethylamino)-ethylene (TMAE). The plasma is found to be characterized by high electron density (10 13-1011cm-3), low electron temperature (~0.1 eV), fast creation (~10 ns) and rapid decaying (electron-ion recombination coefficient ~10-6 cm3/s). Fast Langmuir probe (LP) techniques are developed for diagnosing this plasma, including a novel probe design and fabrication, a fast detection system, sampling, indirect probe heating, electro-magnetic shielding and dummy probe techniques. Plasma physical processes regarding fast LP diagnostics for different time scales (t> and <100 ns) are studied. A theory for the correction due to a rapidly decaying plasma to LP measurements is developed. The mechanisms responsible for the plasma decay are studied, and a delayed ionization process is found to be important in interpreting the decay processes. It is also found that nitrogen can enhance the delayed emission of a TMAE Rydberg state from the TMAE plasma. This result strongly suggests that a long-lifetime highly-excited state is important in the TMAE plasma decay process. This result supports the delayed ionization mechanism. A model combining electron-ion recombination and delayed ionization processes is developed to calculate the delayed ionization lifetime.

  20. Urethral stricture vaporization with the KTP laser provides evidence for a favorable impact of laser surgery on wound healing

    NASA Astrophysics Data System (ADS)

    Schmidlin, Franz R.; Venzi, Giordano; Jichlinski, Patrice; Oswald, Michael; Delacretaz, Guy P.; Gabbiani, Giulio; Leisinger, Hans-Juerg; Graber, Peter

    1997-12-01

    The objective of this study was to evaluate and compare the safety and efficacy of the KTP 532 laser to direct vision internal urethrotomy (DVIU) in the management of urethral strictures. A total of 32 patients were randomized prospectively in this study, 14 DVIU and 18 KTP 532 laser. Patients were evaluated postoperatively with flowmetry and in the case of recurrence with cystourethrography at 3, 12, 24 weeks. With the KTP 532 laser complete symptomatic and uredynamic success was achieved in 15 (83%) patients at 12 and 24 weeks. Success rate was lower in the DVIU group with 9 (64%) patients at 12 weeks and 8 (57%) patients at 24 weeks. Mean preoperative peak-flow was improved from 6 cc/s to 20 cc/s at 3, 12 and 24 weeks with the KTP laser. With DVIU mean preoperative peak-flow was improved from 5.5 cc/s to 20 cc/s at 3 weeks followed by a steady decrease to 13 cc/s at 12 weeks and to 12 cc/s 24 weeks. No complication was observed in either group of patients. Our results confirm that stricture vaporization with the KTP 532 laser is a safe and efficient procedure. The better results after laser surgery make it also a valuable alternative in the endoscopic treatment of urethral strictures. These findings suggest a favorable influence of laser surgery on wound healing with less wound contraction and scarring. The lack of contraction of laser wounds might be related to the absence and the lack of organization of myofibroblasts in laser induced lesions.

  1. Field evaluation of mercury vapor analytical methods: comparison of the "double amalgam method" and ISO 17733.

    PubMed

    Takaya, Mitsutoshi; Joeng, Jee Yeon; Ishihara, Nobuo; Serita, Fumio; Kohyama, Norihiko

    2006-04-01

    In this study, a gold amalgam method called the "Double amalgam method" was compared with the ISO 17733 method for mercury vapor analysis method. In terms of sensitivity and ease of operation, the amalgamation method is superior to the oxidation method. Two parallel samplings were carried out in this research at a button battery factory, where the mercury vapor level in the air was about 0.001 mg/m3 and at a fluorescent lamp factory, where the mercury vapor level was about 0.015 mg/m3. In the both cases, the measured values of the two showed good agreement with each other. As these two workplaces represent typical mercury levels in industries today, the double amalgam method is applicable to working environment measurement.

  2. Optically pumped Cs vapor lasers: pump-to-laser beam overlap optimization

    NASA Astrophysics Data System (ADS)

    Auslender, Ilya; Cohen, Tom; Lebiush, Eyal; Barmashenko, Boris D.; Rosenwaks, Salman

    2017-01-01

    We present the results of an experimental study of Ti:Sapphire pumped Cs laser and theoretical modeling of these results, where we focused on the influence of the pump-to-laser beam overlap, a crucial parameter for optimizing the output laser power. The dependence of the output laser power on the incident pump power was found for varying pump beam cross-section widths and for a constant laser beam. Maximum laser power > 370 mW with an optical-to-optical efficiency of 43% and slope efficiency 55% was obtained. Non monotonic dependence of the laser power and threshold power on the pump beam radius (at a given pump power) was observed with a maximum laser power and minimum threshold power achieved at the ratio 0.7 between the optimal pump beam and laser beam radius. A simple optical model of the laser, where Gaussian spatial shapes of the pump and laser intensities in any cross section of the beams were assumed, was compared to the experiments. Good agreement was obtained between the measured and calculated dependence of the laser power on the incident pump power at different pump beam radii and of the laser power, threshold power and optimal temperature on the pump beam radius. The model does not use empirical parameters such as mode overlap efficiency but rather the pump and laser beam spatial shapes as input parameters. This model can be applied to different optically pumped alkali lasers with arbitrary spatial distributions of the pump and laser beam widths.

  3. Relationship between 578-nm (copper vapor) laser beam geometry and heat distribution within biological tissues

    NASA Astrophysics Data System (ADS)

    Ilyasov, Ildar K.; Prikhodko, Constantin V.; Nevorotin, Alexey J.

    1995-01-01

    Monte Carlo (MC) simulation model and the thermoindicative tissue phantom were applied for evaluation of a depth of tissue necrosis (DTN) as a result of quasi-cw copper vapor laser (578 nm) irradiation. It has been shown that incident light focusing angle is essential for DTN. In particular, there was a significant rise in DTN parallel to elevation of this angle up to +20 degree(s)C and +5 degree(s)C for both the MC simulation and tissue phantom models, respectively, with no further increase in the necrosis depth above these angles. It is to be noted that the relationship between focusing angles and DTN values was apparently stronger for the real target compared to the MC-derived hypothetical one. To what extent these date are applicable for medical practice can be evaluated in animal models which would simulate laser-assisted therapy for PWS or related dermatologic lesions with converged 578 nm laser beams.

  4. Effect of laser power on orientation and microstructure of Ba2TiO4 film prepared by laser chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Guo, Dongyun; Goto, Takashi; Wang, Chuanbin; Shen, Qiang; Zhang, Lianmeng

    2012-08-01

    Ba2TiO4 films were prepared on Pt/Ti/SiO2/Si substrates by laser chemical vapor deposition method. The effect of laser power (PL) on orientation and microstructure was investigated. With increasing PL from 52 to 93 W, the deposition temperature (Tdep) increased from 845 to 946 K. With increasing Tdep from 845 to 927 K, the preferred orientation of Ba2TiO4 films changed from (0 9 1) to (1 0 3), the surface morphologies changed from faceted to rectangular, and the columnar cross-section became thicker. The films prepared at high Tdep (931-946 K) had the porous cross-section consisted of powder-like grains. Ba2TiO4 film prepared at 881 K had high deposition rate (Rdep) of 51.4 μm h-1, which was advantageous to industrial production.

  5. Differential absorption lidar measurements of atmospheric water vapor using a pseudonoise code modulated AlGaAs laser. Thesis

    NASA Technical Reports Server (NTRS)

    Rall, Jonathan A. R.

    1994-01-01

    Lidar measurements using pseudonoise code modulated AlGaAs lasers are reported. Horizontal path lidar measurements were made at night to terrestrial targets at ranges of 5 and 13 km with 35 mW of average power and integration times of one second. Cloud and aerosol lidar measurements were made to thin cirrus clouds at 13 km altitude with Rayleigh (molecular) backscatter evident up to 9 km. Average transmitter power was 35 mW and measurement integration time was 20 minutes. An AlGaAs laser was used to characterize spectral properties of water vapor absorption lines at 811.617, 816.024, and 815.769 nm in a multipass absorption cell using derivative spectroscopy techniques. Frequency locking of an AlGaAs laser to a water vapor absorption line was achieved with a laser center frequency stability measured to better than one-fifth of the water vapor Doppler linewidth over several minutes. Differential absorption lidar measurements of atmospheric water vapor were made in both integrated path and range-resolved modes using an externally modulated AlGaAs laser. Mean water vapor number density was estimated from both integrated path and range-resolved DIAL measurements and agreed with measured humidity values to within 6.5 percent and 20 percent, respectively. Error sources were identified and their effects on estimates of water vapor number density calculated.

  6. Elucidating the Structure of Sugars: MW Spectroscopy Combined with Ultrafast UV Laser Vaporization

    NASA Astrophysics Data System (ADS)

    Cocinero, Emilio J.; Ecija, Patricia; Basterretxea, Francisco J.; Fernandez, Jose A.; Castano, Fernando; Lesarri, Alberto; Grabow, Jens-Uwe; Cimas, Alvaro

    2013-06-01

    Carbohydrates are one of the most versatile biochemicalbuilding blocks, widely acting in energetic, structural or recognition processes. Even the small monosaccharides display unique structural and conformational freedom and may coexist in many open-chain or cyclic forms. We recently initiated the investigation of a series of monosaccharides using a combination of ultrafast laser vaporization and microwave spectroscopy in supersonic jet expansions. We present several structural studies on carbohydrates of aldoses and ketoses of five and six carbon sugars vaporized by UV ultrafast laser vaporization and stabilized in a jet expansion. The experimental evidence confirms that sugars exhibits a α-/β-pyranose conformation (6-membered ring), sharply contrasting with the furanose form (5-membered ring) found in the nature (as component of RNA, sucrose). In addition, thanks to the use of enriched samples, we have experimentally determined the substitution and effective structures. Finally, the structure of several monosaccharides was compared and common structural patterns of their conformational landscape will be showed. E. J. Cocinero, A. Lesarri, P. écija, F. J. Basterretxea, J. U. Grabow, J. A. Fernández and F. Castaño Angew. Chem. Int. Ed. 51, 3119-3124, 2012. E. J. Cocinero, A. Lesarri, P. écija, Á. Cimas, B. G. Davis, F. J. Basterretxea, J. A. Fernández and F. Castaño J. Am. Chem. Soc. 135, 2845-2852, 2013.

  7. Method of physical vapor deposition of metal oxides on semiconductors

    DOEpatents

    Norton, David P.

    2001-01-01

    A process for growing a metal oxide thin film upon a semiconductor surface with a physical vapor deposition technique in a high-vacuum environment and a structure formed with the process involves the steps of heating the semiconductor surface and introducing hydrogen gas into the high-vacuum environment to develop conditions at the semiconductor surface which are favorable for growing the desired metal oxide upon the semiconductor surface yet is unfavorable for the formation of any native oxides upon the semiconductor. More specifically, the temperature of the semiconductor surface and the ratio of hydrogen partial pressure to water pressure within the vacuum environment are high enough to render the formation of native oxides on the semiconductor surface thermodynamically unstable yet are not so high that the formation of the desired metal oxide on the semiconductor surface is thermodynamically unstable. Having established these conditions, constituent atoms of the metal oxide to be deposited upon the semiconductor surface are directed toward the surface of the semiconductor by a physical vapor deposition technique so that the atoms come to rest upon the semiconductor surface as a thin film of metal oxide with no native oxide at the semiconductor surface/thin film interface. An example of a structure formed by this method includes an epitaxial thin film of (001)-oriented CeO.sub.2 overlying a substrate of (001) Ge.

  8. Soft-Bake Purification of SWCNTs Produced by Pulsed Laser Vaporization

    NASA Technical Reports Server (NTRS)

    Yowell, Leonard; Nikolaev, Pavel; Gorelik, Olga; Allada, Rama Kumar; Sosa, Edward; Arepalli, Sivaram

    2013-01-01

    The "soft-bake" method is a simple and reliable initial purification step first proposed by researchers at Rice University for single-walled carbon nanotubes (SWCNT) produced by high-pressure carbon mon oxide disproportionation (HiPco). Soft-baking consists of annealing as-produced (raw) SWCNT, at low temperatures in humid air, in order to degrade the heavy graphitic shells that surround metal particle impurities. Once these shells are cracked open by the expansion and slow oxidation of the metal particles, the metal impurities can be digested through treatment with hydrochloric acid. The soft-baking of SWCNT produced by pulsed-laser vaporization (PLV) is not straightforward, because the larger average SWCNT diameters (.1.4 nm) and heavier graphitic shells surrounding metal particles call for increased temperatures during soft-bake. A part of the technology development focused on optimizing the temperature so that effective cracking of the graphitic shells is balanced with maintaining a reasonable yield, which was a critical aspect of this study. Once the ideal temperature was determined, a number of samples of raw SWCNT were purified using the soft-bake method. An important benefit to this process is the reduced time and effort required for soft-bake versus the standard purification route for SWCNT. The total time spent purifying samples by soft-bake is one week per batch, which equates to a factor of three reduction in the time required for purification as compared to the standard acid purification method. Reduction of the number of steps also appears to be an important factor in improving reproducibility of yield and purity of SWCNT, as small deviations are likely to get amplified over the course of a complicated multi-step purification process.

  9. Evaluation of tunable diode laser absorption spectroscopy for in-process water vapor mass flux measurements during freeze drying.

    PubMed

    Gieseler, Henning; Kessler, William J; Finson, Michael; Davis, Steven J; Mulhall, Phillip A; Bons, Vincent; Debo, David J; Pikal, Michael J

    2007-07-01

    The goal of this work was to demonstrate the use of Tunable Diode Laser Absorption Spectroscopy (TDLAS) as a noninvasive method to continuously measure the water vapor concentration and the vapor flow velocity in the spool connecting a freeze-dryer chamber and condenser. The instantaneous measurements were used to determine the water vapor mass flow rate (g/s). The mass flow determinations provided a continuous measurement of the total amount of water removed. Full load runs of pure water at different pressure and shelf temperature settings and a 5% (w/w) mannitol product run were performed in both laboratory and pilot scale freeze dryers. The ratio of "gravimetric/TDLAS" measurements of water removed was 1.02 +/- 0.06. A theoretical heat transfer model was used to predict the mass flow rate and the model results were compared to both the gravimetric and TDLAS data. Good agreement was also observed in the "gravimetric/TDLAS" ratio for the 5% mannitol runs dried in both freeze dryers. The endpoints of primary and secondary drying for the product runs were clearly identified. Comparison of the velocity and mass flux profiles between the laboratory and pilot dryers indicated a higher restriction to mass flow for the lab scale freeze dryer.

  10. Reduction of degradation in vapor phase transported InP/InGaAsP mushroom stripe lasers

    SciTech Connect

    Jung, H.; Burkhardt, E.G.; Pfister, W.

    1988-10-03

    The rapid degradation rate generally observed in InP/InGaAsP mushroom stripe lasers can be considerably decreased by regrowing the open sidewalls of the active stripe with low-doped InP in a second epitaxial step using the hydride vapor phase transport technique. This technique does not change the fundamental laser parameters like light-current and current-voltage characteristics. Because of this drastic reduction in degradation, the vapor phase epitaxy regrown InP/InGaAsP mushroom laser seems to be an interesting candidate for application in optical communication.

  11. Theoretical studies of Resonance Enhanced Stimulated Raman Scattering (RESRS) of frequency-doubled Alexandrite laser wavelength in cesium vapor

    NASA Technical Reports Server (NTRS)

    Lawandy, Nabil M.

    1987-01-01

    The solutions for the imaginary susceptibility of the Raman field transition with arbitrary relaxation rates and field strengths are examined for three different sets of relaxation rates. These rates correspond to: (1) Far Infrared (FIR) Raman lasers in the diabatic collision regime without consideration of coupled population decay in a closed system, (2) Raman FIR lasers in the diabatic collision regime with coupled population conserving decay, and (3) IR Raman gain in cesium vapor. The model is further expanded to include Doppler broadening and used to predict the peak gain as a function of detuning for a frequency doubled Alexandrite laser-pumped cesium vapor gain cell.

  12. Assessment of the application of cascade lasers to stand-off detection of alcohol vapors in moving cars

    NASA Astrophysics Data System (ADS)

    Mlynczak, Jaroslaw; Kubicki, Jan; Kopczynski, Krzysztof; Mierczyk, Jadwiga

    2016-10-01

    The idea of using commercially available cascade lasers for stand-off detection of alcohol vapors in moving cars is presented. Special attention is paid to the optical characteristics of the car windowpanes for the monitoring as well as for the reference laser beams. A special experimental setup was built to investigate the idea. It is shown that using interband cascade lasers operating at 3.45- and 3.59-μm wavelengths, the alcohol vapors inside a car can be successfully detected, even in cars with different windowpanes.

  13. Method for the generation of variable density metal vapors which bypasses the liquidus phase

    DOEpatents

    Kunnmann, Walter; Larese, John Z.

    2001-01-01

    The present invention provides a method for producing a metal vapor that includes the steps of combining a metal and graphite in a vessel to form a mixture; heating the mixture to a first temperature in an argon gas atmosphere to form a metal carbide; maintaining the first temperature for a period of time; heating the metal carbide to a second temperature to form a metal vapor; withdrawing the metal vapor and the argon gas from the vessel; and separating the metal vapor from the argon gas. Metal vapors made using this method can be used to produce uniform powders of the metal oxide that have narrow size distribution and high purity.

  14. Direct measurement of chemical composition of SOx in impact vapor using a laser gun

    NASA Astrophysics Data System (ADS)

    Ohno, Sohsuke; Kadono, Toshihiko; Kurosawa, Kosuke; Hamura, Taiga; Sakaiya, Tatsuhiro; Sugita, Seiji; Shigemori, Keisuke; Hironaka, Yoichiro; Watari, Takeshi; Matsui, Takafumi

    2011-06-01

    The SO3/SO2 ratio of the impact vapor cloud is a key parameter for understanding the environmental perturbation caused by the impact-induced SOx and the killing mechanism of. the mass extinction at the K-Pg boundary. We conducted hypervelocity impact experiments using a high-speed laser gun (GEKKO XII-HIPER, ILE, Osaka University) and measured the chemical compositions of the SOx released from CaSO4. The experimental result indicates that SOx are dominated by SO3. It implies that the SOx generated by the K-Pg impact would have been also dominated by SO3, because the SO3/SO2 ratio of natural planetary scale impact vapor clouds would have been larger than that of the experimental result of this study.

  15. High-gain inner-shell photoionization laser in Cd vapor pumped by soft-x-ray radiation from a laser-produced plasma source.

    PubMed

    Silfvast, W T; Macklin, J J; Ii, O R

    1983-11-01

    A soft-x-ray-pumped inner-shell photoionization laser has been produced in Cd vapor at 4416 and 3250 A. A gain of 5.6 cm(-1) has been measured at 4416 A, and a reasonably high-energy storage of 0.2 mJ/cm(3) in the upper laser states has been obtained.

  16. Theory and experiments of dye lasers longitudinally pumped by copper vapor laser (CVL)

    NASA Astrophysics Data System (ADS)

    Sun, W.; Tang, C. S.; Zhuge, X. B.; Chen, M. S.

    1986-06-01

    Theoretical and experimental studies were performed on high prf dye lasers longitudinally pumped by CVL. Analytic expressions were derived for the laser output power and efficiency by using a rate equation treatment and taking the influence of excited singlet-state absorption into account. A CuBr laser-pumped dye laser with longitudinally pumped geometry and a jet stream was used in the experiment. A maximum output power of 1.3 W was achieved for Kiton red dye with an efficiency of 40%. Experimental results were in good agreement with theoretical analysis.

  17. Waterproof Silicone Coatings of Thermal Insulation and Vaporization Method

    NASA Technical Reports Server (NTRS)

    Cagliostro, Domenick E. (Inventor)

    1999-01-01

    Thermal insulation composed of porous ceramic material can be waterproofed by producing a thin silicone film on the surface of the insulation by exposing it to volatile silicone precursors at ambient conditions. When the silicone precursor reactants are multi-functional siloxanes or silanes containing alkenes or alkynes carbon groups higher molecular weight films can be produced. Catalyst are usually required for the silicone precursors to react at room temperature to form the films. The catalyst are particularly useful in the single component system e.g. dimethylethoxysilane (DNMS) to accelerate the reaction and decrease the time to waterproof and protect the insulation. In comparison to other methods, the chemical vapor technique assures better control over the quantity and location of the film being deposited on the ceramic insulation to improve the waterproof coating.

  18. Combustion chamber and thermal vapor stream producing apparatus and method

    DOEpatents

    Sperry, John S.; Krajicek, Richard W.; Cradeur, Robert R.

    1978-01-01

    A new and improved method and apparatus for burning a hydrocarbon fuel for producing a high pressure thermal vapor stream comprising steam and combustion gases for injecting into a subterranean formation for the recovery of liquefiable minerals therefrom, wherein a high pressure combustion chamber having multiple refractory lined combustion zones of varying diameters is provided for burning a hydrocarbon fuel and pressurized air in predetermined ratios injected into the chamber for producing hot combustion gases essentially free of oxidizing components and solid carbonaceous particles. The combustion zones are formed by zones of increasing diameters up a final zone of decreasing diameter to provide expansion zones which cause turbulence through controlled thorough mixing of the air and fuel to facilitate complete combustion. The high pressure air and fuel is injected into the first of the multiple zones where ignition occurs with a portion of the air injected at or near the point of ignition to further provide turbulence and more complete combustion.

  19. Development of a new laser heating system for thin film growth by chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Fujimoto, Eiji; Sumiya, Masatomo; Ohnishi, Tsuyoshi; Lippmaa, Mikk; Takeguchi, Masaki; Koinuma, Hideomi; Matsumoto, Yuji

    2012-09-01

    We have developed a new laser heating system for thin film growth by chemical vapor deposition (CVD). A collimated beam from a high-power continuous-wave 808 nm semiconductor laser was directly introduced into a CVD growth chamber without an optical fiber. The light path of the heating laser inside the chamber was isolated mechanically from the growth area by bellows to protect the optics from film coating. Three types of heat absorbers, (10 × 10 × 2 mm3) consisting of SiC, Ni/NiOx, or pyrolytic graphite covered with pyrolytic BN (PG/PBN), located at the backside of the substrate, were tested for heating performance. It was confirmed that the substrate temperature could reach higher than 1500 °C in vacuum when a PG/PBN absorber was used. A wide-range temperature response between 400 °C and 1000 °C was achieved at high heating and cooling rates. Although the thermal energy loss increased in a H2 gas ambient due to the higher thermal conductivity, temperatures up to 1000°C were achieved even in 200 Torr H2. We have demonstrated the capabilities of this laser heating system by growing ZnO films by metalorganic chemical vapor deposition. The growth mode of ZnO films was changed from columnar to lateral growth by repeated temperature modulation in this laser heating system, and consequently atomically smooth epitaxial ZnO films were successfully grown on an a-plane sapphire substrate.

  20. Isolating Protein Charge State Reduction in Electrospray Droplets Using Femtosecond Laser Vaporization

    NASA Astrophysics Data System (ADS)

    Karki, Santosh; Sistani, Habiballah; Archer, Jieutonne J.; Shi, Fengjian; Levis, Robert J.

    2017-01-01

    Charge state distributions are measured using mass spectrometry for both native and denatured cytochrome c and myoglobin after laser vaporization from the solution state into an electrospray (ES) plume consisting of a series of solution additives differing in gas-phase basicity. The charge distribution depends on both the pH of the protein solution prior to laser vaporization and the gas-phase basicity of the solution additive employed in the ES solvent. Cytochrome c (myoglobin) prepared in solutions with pH of 7.0, 2.6, and 2.3 resulted in the average charge state distribution (Zavg) of 7.0 ± 0.1 (8.2 ± 0.1), 9.7 ± 0.2 (14.5 ± 0.3), and 11.6 ± 0.3 (16.4 ± 0.1), respectively, in ammonium formate ES solvent. The charge distribution shifted from higher charge states to lower charge states when the ES solvent contained amines additives with higher gas-phase basicity. In the case of triethyl ammonium formate, Zavg of cytochrome c (myoglobin) prepared in solutions with pH of 7.0, 2.6, and 2.3 decreased to 4.9 (5.7), 7.4 ± 0.2 (9.6 ± 0.3), and 7.9 ± 0.3 (9.8 ± 0.2), respectively. The detection of a charge state distribution corresponding to folded protein after laser vaporized, acid-denatured protein interacts with the ES solvent containing ammonium formate, ammonium acetate, triethyl ammonium formate, and triethyl ammonium acetate suggests that at least a part of protein population folds within the electrospray droplet on a millisecond timescale.

  1. Isolating Protein Charge State Reduction in Electrospray Droplets Using Femtosecond Laser Vaporization

    NASA Astrophysics Data System (ADS)

    Karki, Santosh; Sistani, Habiballah; Archer, Jieutonne J.; Shi, Fengjian; Levis, Robert J.

    2017-03-01

    Charge state distributions are measured using mass spectrometry for both native and denatured cytochrome c and myoglobin after laser vaporization from the solution state into an electrospray (ES) plume consisting of a series of solution additives differing in gas-phase basicity. The charge distribution depends on both the pH of the protein solution prior to laser vaporization and the gas-phase basicity of the solution additive employed in the ES solvent. Cytochrome c (myoglobin) prepared in solutions with pH of 7.0, 2.6, and 2.3 resulted in the average charge state distribution (Zavg) of 7.0 ± 0.1 (8.2 ± 0.1), 9.7 ± 0.2 (14.5 ± 0.3), and 11.6 ± 0.3 (16.4 ± 0.1), respectively, in ammonium formate ES solvent. The charge distribution shifted from higher charge states to lower charge states when the ES solvent contained amines additives with higher gas-phase basicity. In the case of triethyl ammonium formate, Zavg of cytochrome c (myoglobin) prepared in solutions with pH of 7.0, 2.6, and 2.3 decreased to 4.9 (5.7), 7.4 ± 0.2 (9.6 ± 0.3), and 7.9 ± 0.3 (9.8 ± 0.2), respectively. The detection of a charge state distribution corresponding to folded protein after laser vaporized, acid-denatured protein interacts with the ES solvent containing ammonium formate, ammonium acetate, triethyl ammonium formate, and triethyl ammonium acetate suggests that at least a part of protein population folds within the electrospray droplet on a millisecond timescale.

  2. An investigation into the output characteristics of a discharge-heated copper vapor laser

    NASA Astrophysics Data System (ADS)

    Wang, Tieh C.; Yang, Ching Y.

    1989-11-01

    The laser output characteristics of a discharge-heated copper vapor laser (CVL) were investigated at a charging voltage of 14.5 kV, laser tube temperature of 1450 C, pulse repetition rate (PRR) range from 0.5 to 9.5 kHz, and buffer gas pressures of 20 and 75 Torr. Changing buffer gas pressure from 20 to 75 Torr causes no significant variation of the rates of relaxation of metastable atoms. Increase of the current rise of pumping pulse with increasing PRR is the predominant factor for improving the laser behavior when PRR is greater than 3.5 kHz with buffer gas pressure of 20 Torr and when PRR is less than 4.5 kHz with buffer gas pressure of 75 Torr. For short pulse applications, the CVL is preferably operated at high PRR and low buffer gas regime. For the 25-W CVL used here, the prepulse electron density should be higher than 10 to the 13th/cu cm for efficient laser operation. The output power of this CVL can be increased to much higher than 30 W if the thermal insulation is optimized and the PRR is increased.

  3. A single surgeon's experience with contact laser vaporization of the prostate

    NASA Astrophysics Data System (ADS)

    Mueller, Edward J.

    1995-05-01

    Herein, I report on my first 50 contact laser prostatectomies performed with the SLT Nd:YAG laser. The obstructed prostatic urethra is opened via contact laser vaporization of the obstructing adenoma. The average pre-op AUA symptom score was 22.9 (range 14 - 30). The average 3 month post-op AUA symptom score was 2.1 (range 0 -8). Eighteen of the patients had the foley catheter removed approximately 4 - 6 hours post-op and were discharged the same day. Thirty patients had the foley catheter removed the morning following surgery and were discharged. And two patients had the foley catheter removed the morning following surgery, but remained in the hospital for medical reasons unrelated to the TURP. Thus, 48 (96%) of the patients were discharged within 24 hours of admission. No patient had to be readmitted to the hospital for any reason. All patients were allowed to return to full activity within 24 hours of discharge. The average hospital cost for the 48 patients discharged within 24 hours was DOL4,694. This compares to the average hospital cost of an electrocautery TURP of DOL6-8000. In summary, contact laser TURP using the SLT Nd:YAG laser relived the symptoms of an obstructing prostate comparable to electrocautery TURP. However, these results were achieved with a much shorter hospitalization, a quicker return to full activity and at a lower cost.

  4. Optimization of the alexandrite laser tuning elements for a water vapor lidar

    NASA Technical Reports Server (NTRS)

    Ponsardin, Patrick; Grossmann, Benoist E.; Higdon, Noah S.; Browell, Edward V.

    1990-01-01

    An overview of some of the developments completed on an alexandrite laser for making water vapor DIAL measurements is presented in this paper. A computer control for active stabilization of the two intracavity etalons has been implemented and recently tested in an aircraft environment. Long-term frequency drift (i.e., 2 hours) of less than 0.7 pm has been observed in the laboratory. An alignment technique to get the optimum free spectral range ratio for the two etalons is also developed.

  5. Thermal vapor bubble and pressure dynamics during infrared laser ablation of tissue

    NASA Astrophysics Data System (ADS)

    Wagner, Wolfgang; Sokolow, Adam; Pearlstein, Robert; Edwards, Glenn

    2009-01-01

    Free-electron laser irradiation can superheat tissue water, driving thermal vapor bubbles confined by tissue matrix and leading to mechanical tissue failure (ablation). Acoustic transients propagating from an ablation cavity were recorded with a polarization quadrature, interferometric vibrometer. For 3.0 μm infrared irradiation, the shocklike transients with peak pressures in the megapascal range indicate amplification due to bubble collapse. In contrast, for 6.45 μm irradiation, elastic transients with peak pressures in the 0.1 MPa range indicate tissue failure during bubble growth.

  6. Evaluation of metal vapor laser designs with radial separation of the active medium

    NASA Astrophysics Data System (ADS)

    Soldatov, Anatoly N.; Polunin, Yu. P.; Chausova, L. N.

    1995-08-01

    Recent advances in self-terminating metal-vapor lasers have largely resulted from the feasibility of scaling laser characteristics in the cylindrical configuration of the active medium and longitudinal pulsed discharge, which makes it possible to provide the average power W > 100W from a large bore laser tube. Increasing the active volume, however, at the expense of a larger bore for this geometry of the gas discharge channel substantially reduces the specific energy Esp and the average specific power Wsp. Notably, the best laser characteristics have been realized with a low average specific input power Psp. The latter ranged between 1.5 and 0.5 W/cm3 for 6-12 cm bore tubes. As Psp was increased above a certain value, Wsp and W were found to decrease. As that took place, there appeared high radial inhomogeneities in the laser power distribution. Among the things which interfere with further increase of W, Wsp, and Esp as the input energy is increased, are radially nonuniform overheating of the active medium and very high degree of ionization. Given high input energies, these factors will give rise to a substantial deficit of ground state metal atoms N(O) at the center of the laser tube. As Psp is increased, the valley in the radial thermal distribution N(R) gets deeper due to ambipolar diffusion. The N(R) variation with excitation conditions has been studied experimentally for cylindrical laser tubes. The primary processes involved have been examined by means of the saturated power model. In this work we have studied laser action from Cu, I, and AuI in a tube whose configuration allows us to ameliorate the effect of a number of limiting factors on the output energy performance, on the one hand, and provides transversely separated excitation zones on the other, which, in turn, makes it possible to realize optimal thermophysical characteristics of the active medium, manipulate the spatial distribution of metal vapor, including the case of simultaneous excitation of

  7. Vapor Corrosion Cell and Method of Using Same

    NASA Technical Reports Server (NTRS)

    Davis, Dennis D. (Inventor)

    2001-01-01

    The present invention provides a vapor corrosion cell for a real-time and quantitative measurement of corrosion of conductive materials in atmospheres containing chemically reactive gases and water vapor. Two prototypes are provided. Also provided are various applications of this apparatus in industry.

  8. Two-photon dichroic atomic vapor laser lock using electromagnetically induced transparency and absorption

    SciTech Connect

    Becerra, F. E.; Willis, R. T.; Rolston, S. L.; Orozco, L. A.

    2009-07-15

    We demonstrate a technique to lock the frequency of a laser to a transition between two excited states in Rb vapor using a two-photon process in the presence of a weak magnetic field. We use a ladder configuration from specific hyperfine sublevels of the 5S{sub 1/2}, 5P{sub 3/2}, and 5D{sub 5/2} levels. This atomic configuration can show electromagnetically induced transparency and absorption processes. The error signal comes from the difference in the transparency or absorption felt by the two orthogonal polarizations of the probe beam. A simplified model is in good quantitative agreement with the observed signals for the experimental parameters. We have used this technique to lock the frequency of the laser up to 1.5 GHz off atomic resonance.

  9. A pneumatically powered mechanical translator-rotator for the direct laser vaporization of solid materials

    NASA Astrophysics Data System (ADS)

    Stone, Earle G.; Bach, Stephan B. H.

    1997-03-01

    A pneumatically powered mechanical translator-rotator system has been designed and constructed for use in the direct laser vaporization (DLV) of materials. This translator-rotator was initially developed for the reproducible DLV production of refractory metal atoms to be reacted with small molecules and characterized in matrix isolation experiments, but has applications wherever a reproducible DLV stream of a material is required, such as matrix assisted laser desorption ionization. Key features of the new translator-rotator design are the employment of an inexpensive air ratchet to provide power for the translator-rotator mechanism, the elimination of magnetic relays and electrical limit switches through the use of an all mechanical gear and slot mechanism, and a triple O-ring gland capable of maintaining high vacuum, 10-7 Torr, while the translator-rotator is in operation.

  10. Gas-dynamic acceleration of laser-ablation plumes: Hyperthermal particle energies under thermal vaporization

    SciTech Connect

    Morozov, A. A.; Evtushenko, A. B.; Bulgakov, A. V.

    2015-02-02

    The expansion of a plume produced by low-fluence laser ablation of graphite in vacuum is investigated experimentally and by direct Monte Carlo simulations in an attempt to explain hyperthermal particle energies for thermally vaporized materials. We demonstrate that the translation energy of neutral particles, ∼2 times higher than classical expectations, is due to two effects, hydrodynamic plume acceleration into the forward direction and kinetic selection of fast particles in the on-axis region. Both effects depend on the collision number within the plume and on the particles internal degrees of freedom. The simulations allow ablation properties to be evaluated, such as ablation rate and surface temperature, based on time-of-flight measurements. Available experimental data on kinetic energies of various laser-produced particles are well described by the presented model.

  11. Formation of rare-earth upconverting nanoparticles using laser vaporization controlled condensation

    NASA Astrophysics Data System (ADS)

    Glaspell, Garry; Wilkins, James R.; Anderson, John; El-Shall, M. Samy

    2008-04-01

    Rare earth doped upconverting nanoparticles have been synthesized via laser vaporization controlled condensation (LVCC) and their photoluminescence properties were characterized using 980 nm laser diode excitation. This procedure is highly tunable, specifically by increasing the Yb 3+ to Er 3+ concentration the observed green emission decreases and the observed red emission increases. We have also shown that nearly equal peaks of blue, green and red emissions producing a virtually white upconverter could be synthesized by appropriately mixing Tm 3+, Ho 3+, and Er 3+. We have also investigated the upconversion efficiency in a variety of lattices including Y IIO 3, Gd IIO 3 and La IIO 3. TEM confirmed that the as-formed particles were ~ 10 nm in size and XRD indicated that the overall crystal structure was predominately cubic.

  12. KTP laser selective vaporization of the prostate in the management of urinary retention due to BPH

    NASA Astrophysics Data System (ADS)

    Kleeman, M. W.; Nseyo, Unyime O.

    2003-06-01

    High-powered photoselective vaporization of the prostate (PVP) is a relatively new addition in the armamentarium against bladder outlet obstruction due to BPH. With BPH, the prostate undergoes stromal and epithelial hyperplasia, particularly in the transitional zone, mediated by dihydrotestosterone (DHT). This periurethral enlargement can compress the prostatic urethra leading to bladder outlet obstruction and eventually urinary retention. Treatment of uncomplicated symptomatic BPH has evolved from the standard transurethral resection of the prostate (TURP) to multiple medical therapies and the putative minimally invasive surgical procedures. These include microwave ablation, needle ablation, balloon dilation, stents, as well as fluid based thermo-therapy, ultrasound therapy and cryotherapy. Different forms of lasers have been applied to treat BPH with variable short and long term benefits of urinary symptoms. However, the controversy remains about each laser regarding its technical applicability and efficacy.

  13. Modeling of Laser Vaporization and Plume Chemistry in a Boron Nitride Nanotube Production Rig

    NASA Technical Reports Server (NTRS)

    Gnoffo, Peter A.; Fay, Catharine C.

    2012-01-01

    Flow in a pressurized, vapor condensation (PVC) boron nitride nanotube (BNNT) production rig is modeled. A laser provides a thermal energy source to the tip of a boron ber bundle in a high pressure nitrogen chamber causing a plume of boron-rich gas to rise. The buoyancy driven flow is modeled as a mixture of thermally perfect gases (B, B2, N, N2, BN) in either thermochemical equilibrium or chemical nonequilibrium assuming steady-state melt and vaporization from a 1 mm radius spot at the axis of an axisymmetric chamber. The simulation is intended to define the macroscopic thermochemical environment from which boron-rich species, including nanotubes, condense out of the plume. Simulations indicate a high temperature environment (T > 4400K) for elevated pressures within 1 mm of the surface sufficient to dissociate molecular nitrogen and form BN at the base of the plume. Modifications to Program LAURA, a finite-volume based solver for hypersonic flows including coupled radiation and ablation, are described to enable this simulation. Simulations indicate that high pressure synthesis conditions enable formation of BN vapor in the plume that may serve to enhance formation of exceptionally long nanotubes in the PVC process.

  14. Kinetics of laser-pulse vaporization of uranium carbide by mass spectrometry. [LMFBR

    SciTech Connect

    Tehranian, F.

    1983-06-01

    The kinetics of uranium carbide vaporization in the temperature range 3000 K to 5200 K was studied using a Nd-glass laser with peak power densities from 1.6 x 10/sup 5/ to 4.0 x 10/sup 5/ watts/cm/sup 2/. The vapor species U, UC/sub 2/, C/sub 1/ and C/sub 3/ were detected and analyzed by a quadrupole mass spectrometer. From the mass spectrometer signals number densities of the various species in the ionizer were obtained as functions of time. The surface of the irradiated uranium carbide was examined by scanning electron microscope and the depth profile of the crater was obtained. In order to aid analysis of the data, the heat conduction and species diffusion equations for the solid (or liquid) were solved numerically by a computer code to obtain the temperature and composition transients during laser heating. A sensitivity analysis was used to study the effect of uncertainties in the input parameters on the computed surface temperatures.

  15. Laser-assisted methods for nanofabrication

    NASA Astrophysics Data System (ADS)

    Kabashin, Andrei V.; Meunier, Michel

    2004-07-01

    An overview of laser-assisted nanofabrication methods, which has been developed in the Laser Processing Laboratory, is presented. All methods imply the laser-related ablation of material from a solid target and the production of nanoparticles or nanostructures. We consider the nanofabrication process in both the gaseous and in the liquid ambience under different parameters of laser radiation. A particular attention is given on the absence or presence of the plasma-related absorption of the laser radiation, which make possible different nanofabrication regimes. The methods lead to a production of nanomaterials, which are of importance for photonics and biosensing applications.

  16. Laser absorption spectroscopy of water vapor confined in nanoporous alumina: wall collision line broadening and gas diffusion dynamics.

    PubMed

    Svensson, Tomas; Lewander, Märta; Svanberg, Sune

    2010-08-02

    We demonstrate high-resolution tunable diode laser absorption spectroscopy (TDLAS) of water vapor confined in nanoporous alumina. Strong multiple light scattering results in long photon pathlengths (1 m through a 6 mm sample). We report on strong line broadening due to frequent wall collisions (gas-surface interactions). For the water vapor line at 935.685 nm, the HWHM of confined molecules are about 4.3 GHz as compared to 2.9 GHz for free molecules (atmospheric pressure). Gas diffusion is also investigated, and in contrast to molecular oxygen (that moves rapidly in and out of the alumina), the exchange of water vapor is found very slow.

  17. Review of Various Air Sampling Methods for Solvent Vapors.

    DTIC Science & Technology

    Vapors of trichloroethylene, toluene, methyl ethyl ketone, and butyl cellosolve in air were collected using Scotchpac and Tedlar bags, glass ...prescription bottles , and charcoal adsorption tubes. Efficiencies of collection are reported. (Author)

  18. Review of Various Air Sampling Methods for Solvent Vapors.

    ERIC Educational Resources Information Center

    Maykoski, R. T.

    Vapors of trichloroethylene, toluene, methyl ethyl ketone, and butyl cellosolve in air were collected using Scotchpac and Tedlar bags, glass prescription bottles, and charcoal adsorption tubes. Efficiencies of collection are reported. (Author/RH)

  19. Critical Fluences And Modeling Of CO{sub 2} Laser Ablation Of Polyoxymethylene From Vaporization To The Plasma Regime

    SciTech Connect

    Sinko, John E.; Phipps, Claude R.; Tsukiyama, Yosuke; Ogita, Naoya; Sasoh, Akihiro; Umehara, Noritsugu; Gregory, Don A.

    2010-05-06

    A CO{sub 2} laser was operated at pulse energies up to 10 J to ablate polyoxymethylene targets in air and vacuum conditions. Critical effects predicted by ablation models are discussed in relation to the experimental data, including specifically the threshold fluences for vaporization and critical plasma formation, and the fluence at which the optimal momentum coupling coefficient is found. Finally, we discuss a new approach for modeling polymers at long wavelengths, including a connection formula that links the vaporization and plasma regimes for laser ablation propulsion.

  20. Spectral diagnostics of a vapor-plasma plume produced during welding titanium with a high-power ytterbium fiber laser

    NASA Astrophysics Data System (ADS)

    Uspenskiy, S. A.; Petrovskiy, V. N.; Bykovskiy, D. P.; Mironov, V. D.; Prokopova, N. M.; Tret'yakov, E. V.

    2015-03-01

    This work is devoted to the research of welding plume during high power ytterbium fiber laser welding of a titanium alloy in the Ar shielding gas environment. High speed video observation of a vapor-plasma plume for visualization of processes occurring at laser welding was carried out. The coefficient of the inverse Bremsstrahlung absorption of laser radiation is calculated for a plasma welding plume by results of spectrometer researches. The conclusion deals with the impact of plasma on a high-power fiber laser radiation.

  1. Method and means for a spatial and temporal probe for laser-generated plumes based on density gradients

    DOEpatents

    Yeung, E.S.; Chen, G.

    1990-05-01

    A method and means are disclosed for a spatial and temporal probe for laser generated plumes based on density gradients includes generation of a plume of vaporized material from a surface by an energy source. The probe laser beam is positioned so that the plume passes through the probe laser beam. Movement of the probe laser beam caused by refraction from the density gradient of the plume is monitored. Spatial and temporal information, correlated to one another, is then derived. 15 figs.

  2. Method and means for a spatial and temporal probe for laser-generated plumes based on density gradients

    DOEpatents

    Yeung, Edward S.; Chen, Guoying

    1990-05-01

    A method and means for a spatial and temporal probe for laser generated plumes based on density gradients includes generation of a plume of vaporized material from a surface by an energy source. The probe laser beam is positioned so that the plume passes through the probe laser beam. Movement of the probe laser beam caused by refraction from the density gradient of the plume is monitored. Spatial and temporal information, correlated to one another, is then derived.

  3. Prediction of water vapor transport rates across polyvinylchloride packaging systems using a novel radiotracer method

    SciTech Connect

    Wood, R.W.; Mulski, M.J.; Kuu, W.Y. )

    1990-09-01

    A radiotracer method is used to study the transport properties of water vapor in polyvinylchloride (PVC), a plastic commonly used in the packaging of parenteral solutions. Water vapor transport across a PVC film appears to be Fickian in nature. Using the steady-state solution of Fick's second law and the permeability coefficient of water vapor across the PVC film obtained using the described method, the predicted water vapor transport rate (WVTR) for a parenteral solution packaged in PVC is in reasonable agreement with actual WVTR as determined by weight loss under precisely controlled conditions.

  4. INTERNATIONAL CONFERENCE ON SEMICONDUCTOR INJECTION LASERS SELCO-87: Metal-organic vapor phase epitaxy of (GaAl)As for 0.85-μm laser diodes

    NASA Astrophysics Data System (ADS)

    Jacobs, K.; Bugge, F.; Butzke, G.; Lehmann, L.; Schimko, R.

    1988-11-01

    Metal-organic vapor phase epitaxy was used to grow stripe heterolaser diodes that were hitherto fabricated by liquid phase epitaxy. The main relationships between the growth parameters (partial input pressures, temperatures) and the properties of materials (thicknesses, solid-solution compositions, carrier densities) were investigated. The results were in full agreement with the mechanism of growth controlled by a vapor-phase diffusion. The results achieved routinely in the growth of GaAs are reported. It is shown that double heterostructure laser diodes fabricated by metal-organic vapor phase epitaxy compete favorably with those grown so far by liquid phase epitaxy, including their degradation and reliability.

  5. The influence of water vapor on atmospheric exchange measurements with an ICOS* based Laser absorption analyzer

    NASA Astrophysics Data System (ADS)

    Bunk, Rüdiger; Quan, Zhi; Wandel, Matthias; Yi, Zhigang; Bozem, Heiko; Kesselmeier, Jürgen

    2014-05-01

    Carbonyl sulfide and carbon monoxide are both atmospheric trace gases of high interest. Recent advances in the field of spectroscopy have enabled instruments that measure the concentration of the above and other trace gases very fast and with good precision. Increasing the effective path length by reflecting the light between two mirrors in a cavity, these instruments reach impressive sensitivities. Often it is possible to measure the concentration of more than one trace gas at the same time. The OCS/CO2 Analyzer by LGR (Los Gatos Research, Inc.) measures the concentration of water vapor [H2O], carbonyl sulfide [COS], carbon dioxide [CO2] and carbon monoxide [CO] simultaneously. For that the cavity is saturated with light, than the attenuation of light is measured as in standard absorption spectroscopy. The instrument proved to be very fast with good precision and to be able to detect even very low concentrations, especially for COS (as low as 30ppt in the case of COS). However, we observed a rather strong cross sensitivity to water vapor. Altering the water vapor content of the sampled air with two different methods led to a change in the perceived concentration of COS, CO and CO2. This proved especially problematic for enclosure (cuvette) measurements, where the concentrations of one of the above species in an empty cuvette are compared to the concentration of another cuvette containing a plant whose exchange of trace gases with the atmosphere is of interest. There, the plants transpiration leads to a large difference in water vapor content between the cuvettes and that in turn produces artifacts in the concentration differences between the cuvettes for the other above mentioned trace gases. For CO, simultaneous measurement with a UV-Emission Analyzer (AL 5002, Aerolaser) and the COS/CO Analyzer showed good agreement of perceived concentrations as long as the sample gas was dry and an increasing difference in perceived concentration when the sample gas was

  6. Method and apparatus to measure vapor pressure in a flow system

    DOEpatents

    Grossman, M.W.; Biblarz, O.

    1991-10-15

    The present invention is directed to a method for determining, by a condensation method, the vapor pressure of a material with a known vapor pressure versus temperature characteristic, in a flow system particularly in a mercury isotope enrichment process. 2 figures.

  7. Measurement of vapor/liquid distributions in a binary-component fuel spray using laser imaging of droplet scattering and vapor absorption

    NASA Astrophysics Data System (ADS)

    Li, Shiyan; Zhang, Yuyin; Wu, Shenqi; Xu, Bin

    2014-08-01

    Fuel volatility has a great effect on its evaporation processes and the mixture formation and thus combustion and emissions formation processes in internal combustion engines. To date, however, instead of the actual gasoline or diesel fuel, many researchers have been using single-component fuel in their studies, because the composition of the former is too complicated to understand the real physics behind the evaporation and combustion characteristics. Several research groups have reported their results on droplets evaporation in a spray of multi-component fuel, carried out both numerically and experimentally. However, there are plenty of difficulties in quantitative determination of vapor concentration and droplet distributions of each component in a multicomponent fuel spray. In this study, to determine the vapor phase concentration and droplet distributions in an evaporating binary component fuel spray, a laser diagnostics based on laser extinction by droplet scattering and vapor absorption was developed. In practice, measurements of the vapor concentration distributions of the lower (n-tridencane) and higher (n-octane) volatility components in the binary component fuel sprays have been carried out at ambient temperatures of 473K and 573K, by substituting p-xylene for noctane or α-methylnaphthalene for n-tridecane. p-Xylene and α-methylnaphthalene were selected as the substitutes is because they have strong absorption band near 266nm and transparent near 532nm and, their thermo-physical properties are similar to those of the original component. As a demonstration experiment, vapor/liquid distribution of the lower boiling point (LBP) and higher boiling point (HBP) components in the binary component fuel spray have been obtained.

  8. Spectral diagnostics of a vapor-plasma plume produced during welding with a high-power ytterbium fiber laser

    NASA Astrophysics Data System (ADS)

    Uspenskiy, S. A.; Shcheglov, P. Yu.; Petrovskiy, V. N.; Gumenyuk, A. V.; Rethmeier, M.

    2013-07-01

    We have conducted spectroscopic studies of the welding plasma formed in the process of welding with an ytterbium fiber laser delivering output power of up to 20 kW. The influence of shielding gases (Ar, He) on different parts of the welding plume is investigated. The absorption coefficient of the laser radiation by the welding-plume plasma is estimated. Scattering of 532-nm probe radiation from particles of the condensed metal vapor within the caustic of a high-power fiber laser beam is measured. Based on the obtained results, conclusions are made on the influence of the plasma formation and metal vapor condensation on the radiation of the high-power fiber laser and the stability of the welding process.

  9. Mid-IR laser absorption diagnostics for hydrocarbon vapor sensing in harsh environments

    NASA Astrophysics Data System (ADS)

    Klingbeil, Adam Edgar

    unburned fuel, engine performance can be characterized and future engine designs can be improved to utilize all of the fuel supplied to the engine. Simultaneous measurement of absorption at two wavelengths is used as a basis for hydrocarbon detection in severe environments. A novel wavelength-tunable mid-IR laser is modified to rapidly switch between two wavelengths, improving the versatility of this laser system. The two-wavelength technique is then exploited to measure vapor concentration while rejecting interferences such as scattering from liquid droplets and absorption from other species. This two-wavelength laser is also used to simultaneously determine temperature and vapor concentration. These techniques, in combination with the library of temperature-dependent hydrocarbon spectra, lay the groundwork necessary to develop fuel diagnostics for laboratory experiments and tests in pulse detonation engines and internal combustion engines. The temperature-dependent spectroscopy of gasoline is examined to develop a sensor for fuel/air ratio in an internal combustion engine. A wavelength was selected for good sensitivity to gasoline concentration. A spectroscopic model is developed that uses the relative concentrations of five structural classes to predict the absorption spectrum of gasoline samples with varying composition. The model is tested on 21 samples of gasoline for temperatures ranging from 300 to 1200 K, showing good agreement between model and measurements over the entire temperature range. Finally, a two-wavelength diagnostic was developed to measure the post-evaporation temperature and n-dodecane concentration in an aerosol-laden shock tube. The experimental data validate a model which calculates the effects of shock-wave compression on a two-phase mixture. The measured post-shock temperature and vapor concentration compare favorably for gas-phase and aerosol experiments. The agreement between the two fuel-loading techniques verifies that this aerosol shock

  10. Retrieval of water vapor mixing ratio from a multiple channel Raman-scatter lidar using an optimal estimation method.

    PubMed

    Sica, R J; Haefele, A

    2016-02-01

    Lidar measurements of the atmospheric water vapor mixing ratio provide an excellent complement to radiosoundings and passive, ground-based remote sensors. Lidars are now routinely used that can make high spatial-temporal resolution measurements of water vapor from the surface to the stratosphere. Many of these systems can operate during the day and night, with operation only limited by clouds thick enough to significantly attenuate the laser beam. To enhance the value of these measurements for weather and climate studies, this paper presents an optimal estimation method (OEM) to retrieve the water vapor mixing ratio, aerosol optical depth profile, Ångstrom exponent, lidar constants, detector dead times, and measurement backgrounds from multichannel vibrational Raman-scatter lidars. The OEM retrieval provides the systematic uncertainties due to the overlap function, calibration factor, air density and Rayleigh-scatter cross sections, in addition to the random uncertainties of the retrieval due to measurement noise. The OEM also gives the vertical resolution of the retrieval as a function of height, as well as the height to which the contribution of the a priori is small. The OEM is applied to measurements made by the Meteoswiss Raman Lidar for Meteorological Observations (RALMO) in the day and night for clear and cloudy conditions. The retrieved water vapor mixing ratio is in excellent agreement with both the traditional lidar retrieval method and coincident radiosoundings.

  11. Study of Pulse Laser Assisted Metalorganic Vapor Phase Epitaxy of InGaN with Large Indium Mole Fraction

    NASA Astrophysics Data System (ADS)

    Kangawa, Yoshihiro; Kawaguchi, Norihito; Hida, Ken-nosuke; Kumagai, Yoshinao; Koukitu, Akinori

    2004-08-01

    The indium composition of the InGaN film increases with decreasing growth temperature; however, the crystalline quality of the film is poor when it is grown at low temperatures. To form a high-quality InGaN film with a large indium mole fraction, Nd: YAG pulse laser assisted metalorganic vapor phase epitaxy (MOVPE) was carried out at low temperatures. The results suggest that film quality can be improved by pulse laser irradiation on the surface of the film.

  12. Laser-Based Measurements of OH, Temperature, and Water Vapor Concentration in a Hydrocarbon-Fueled Scramjet (POSTPRINT)

    DTIC Science & Technology

    2008-07-01

    its cowl wall. The combustor had over 200 pressure taps instrumented on all four walls, including measurements at the combustor exit and in the base...connect hydrocarbon-fueled scramjet combustor . Planar laser- induced fluorescence (PLIF) of the OH radical is used to examine the flame structure...within the combustor . Tunable diode laser- based absorption spectroscopy (TDLAS) is used to measure water vapor concentration and static temperature near

  13. Buffer gas-assisted four-wave mixing resonances in alkali vapor excited by a single cw laser

    NASA Astrophysics Data System (ADS)

    Shmavonyan, Svetlana; Khanbekyan, Aleksandr; Khanbekyan, Alen; Mariotti, Emilio; Papoyan, Aram V.

    2016-12-01

    We report the observation of a fluorescence peak appearing in dilute alkali (Rb, Cs) vapor in the presence of a buffer gas when the cw laser radiation frequency is tuned between the Doppler-broadened hyperfine transition groups of an atomic D2 line. Based on steep laser radiation intensity dependence above the threshold and spectral composition of the observed features corresponding to atomic resonance transitions, we have attributed these features to the buffer gas-assisted four-wave mixing process.

  14. Microstructure of metastable metallic alloy films produced by laser breakdown chemical vapor deposition and ion implantation

    SciTech Connect

    Menon, S.K.; Jervis, T.R.; Nastasi, M.

    1986-01-01

    Thin films produced by laser breakdown chemical vapor deposition from nickel and iron carbonyls and by implanting Ni foils with varying levels of C have been characterized by transmission electron microscopy. Decomposition of Ni(CO)/sub 4/ produces polycrystalline films of fcc Ni and metastable ordered hexagonal Ni/sub 3/C. This metastable phase is identical to that produced by gas carburization, rapid solidification of Ni-C melts, and ion implantation of C into Ni at low concentrations. Increasing the H/sub 2/ content in the gas mixture during laser deposition reduces the grain size of the films significantly with grain sizes smaller than 10 nanometers produced. Laser decomposition of Fe(CO)/sub 5/ produces films with islands of fcc gamma-Fe and finely dispersed metastable Fe/sub 3/C (Cementite). In addition, the ferrous oxides Fe/sub 2/O/sub 3/ and Fe/sub 3/O/sub 4/ were found in these samples. Implants of C into pure Ni foils at 77/sup 0/K and at a concentration of 35 at. % produced amorphous layers. Implants at the same dose at room temperature did not produce amorphous layers.

  15. A three-beam water vapor sensor system for combustion diagnostics using a 1390 nm tunable diode laser

    SciTech Connect

    Wang, L.G.; Vay, S.

    1995-12-31

    H{sub 2}O(v) is an important species in combustion and hypersonic flow measurements because it is a primary combustion product. Measurements of water vapor can be used to determine performance parameters, such as extent and efficiency of combustion in propulsion and aerodynamics facilities. Water vapor concentration measurement in these high-temperature hypervelocity combustion conditions requires very high sensitivity and fast time response. A three-beam diode laser H{sub 2}O(v) measurement system for nonintrusive combustion diagnostics has been developed at NASA Langley Research Center and successfully tested and installed at GASL NASA HYPULSE facility for routine operation. The system was built using both direct laser absorption spectroscopy and frequency modulation laser spectroscopy. The output beam from a distributed feedback (DFB) InGaAsP diode laser (emitting around 1.39 {micro}m) is split into three equal-powered equal-distanced parallel beams with separation of 9 mm. With three beams, the authors are able to obtain water vapor number densities at three locations. Frequency modulation spectroscopy technique is used to achieve high detection sensitivity. The diode laser is modulated at radio frequency (RF), while the wavelength of the diode laser is tuned to scan over a strong water vapor absorption line. The detected RF signal is then demodulated at the fundamental frequency of the modulation (one-F demodulation). A working model and a computer software code have been developed for data process and data analysis. Water vapor number density measurements are achieved with consideration of temperature dependence. Experimental results and data analysis will be presented.

  16. Long-laser-pulse method of producing thin films

    DOEpatents

    Balooch, Mehdi; Olander, Donald K.; Russo, Richard E.

    1991-01-01

    A method of depositing thin films by means of laser vaporization employs a long-pulse laser (Nd-glass of about one millisecond duration) with a peak power density typically in the range 10.sup.5 -10.sup.6 W/cm.sup.2. The method may be used to produce high T.sub.c superconducting films of perovskite material. In one embodiment, a few hundred nanometers thick film of YBa.sub.2 Cu.sub.3 O.sub.7-x is produced on a SrTiO.sub.3 crystal substrate in one or two pulses. In situ-recrystallization and post-annealing, both at elevated temperature and in the presence of an oxidizing agen The invention described herein arose in the course of, or under, Contract No. DE-C03-76SF0098 between the United States Department of Energy and the University of California.

  17. Water vapor lidar

    NASA Technical Reports Server (NTRS)

    Ellingson, R.; Mcilrath, T.; Schwemmer, G.; Wilkerson, T. D.

    1976-01-01

    The feasibility was studied of measuring atmospheric water vapor by means of a tunable lidar operated from the space shuttle. The specific method evaluated was differential absorption, a two-color method in which the atmospheric path of interest is traversed by two laser pulses. Results are reported.

  18. Determination of cadmium vapor pressure over dichromium cadmium tetraselenide by the atomic absorption method

    SciTech Connect

    Bel'skii, N.K.; Ochertyanova L.I.; Zhegalinka, V.A.

    1986-07-01

    By the atomic absorption method one measures the light absorption by the vapor of the investigated element as a function of the temperature of the evaporating surface. To measure vapor pressure the authors use cadmium selenide of the purity grade, which was recrystallized by sublimitation. The optical density of the vapor over cadmium selenide was determined in the temperature range 820-890 K. Using atomic spectroscopy the vapor pressure of cadmium over cadmium selenide was determined in dichromium cadmium tetraselenide with different amounts of deviation from stoichiometry at 790-880 deg. The results are compared with the literature data.

  19. C-BN patterned single-walled nanotubes synthesized by laser vaporization.

    PubMed

    Enouz, Shaïma; Stéphan, Odile; Cochon, Jean-Lou; Colliex, Christian; Loiseau, Annick

    2007-07-01

    We report on the synthesis of C-BN single-walled nanotubes made of BN nanodomains embedded into a graphene layer. The synthesis process consists of vaporizing, by a continuous CO2 laser, a target made of carbon and boron mixed with a Co/Ni catalyst under N2 atmosphere. High-resolution transmission electron microscopy (HRTEM) and nanoelectron energy loss spectroscopy (nanoEELS) provide direct evidence that boron and nitrogen co-segregate with respect to carbon and form nanodomains within the hexagonal lattice of the graphene layer in a sequential manner. A growth model is proposed to account for the observed C-BN self-organization and to explain how kinetics and local energetics at intermediate states can tailor ultimate single layer BN-C heterojunctions.

  20. Root-growth mechanism for single-walled boron nitride nanotubes in laser vaporization technique.

    PubMed

    Arenal, Raul; Stephan, Odile; Cochon, Jean-Lou; Loiseau, Annick

    2007-12-26

    We present a detailed study of the growth mechanism of single-walled boron nitride nanotubes synthesized by laser vaporization, which is the unique route known to the synthesis of this kind of tube in high quantities. We have performed a nanometric chemical and structural characterization by transmission electron microscopy (high-resolution mode (HRTEM) and electron energy loss spectroscopy) of the synthesis products. Different boron-based compounds and other impurities were identified in the raw synthesis products. The results obtained by the TEM analysis and from the synthesis parameters (temperature, boron, and nitrogen sources) combined with phase diagram analysis to provide identification of the fundamental factors determining the nanotube growth mechanism. Our experiments strongly support a root-growth model that involves the presence of a droplet of boron. This phenomenological model considers the solubility, solidification, and segregation phenomena of the elements present in this boron droplet. In this model, we distinguish three different steps as a function of the temperature: (1) formation of the liquid boron droplet from the decomposition of different boron compounds existing in the hexagonal boron nitride target, (2) reaction of these boron droplets with nitrogen gas present in the vaporization chamber and recombination of these elements to form boron nitride, and (3) incorporation of the nitrogen atoms at the root of the boron particle at active reacting sites that achieves the growth of the tube.

  1. In vitro study on the vaporization ratio of 2-microm laser in human prostatic tissue.

    PubMed

    Yang, Yong; Sun, Dongchong; Wei, Zhitao; Xu, Feng; Hong, Baofa; Zhang, Xu

    2010-04-01

    In this study, the vaporization ratio of the 2-mum laser in the prostatic tissue with benign prostatic hyperplasia was examined in vitro, to explore a technique to estimate the clearance rate of prostatic tissue during the transurethral vaporesection of the prostate. A total of 9 fresh prostatic tissue specimens were obtained by open surgery and the wet weight of the prostatic tissue were measured immediately after the sample collection. Under the simulated conditions of transurethral vaporesection of the prostate by 2-microm laser, each prostate gland was completely vaporesected into fragments with a diameter of less than 1.0 cm in vitro. After the vaporesection, the whole fragments of prostatic tissue were collected and measured. Then the lost weight of prostatic tissue, the weight of the collected prostatic tissue and the ratio of the lost weight of prostatic tissue to the wet weight of the prostate glandular organ specimen were calculated. The correlation between the weight of collected prostatic tissue and the weight of the whole glandular organ was analyzed. All the experimental procedures were carried out by one operator. Wet weight of the prostatic gland specimen and the weight of the harvested prostatic tissues after the procedure were recorded. With respect to the wet weight of prostate gland specimen, the percentage of the weight of collected prostatic tissue was (34.45 + or - 1.51) %, and the percentage of the lost weight of prostatic tissue was (65.55 + or - 1.51)%. Satisfactory linear relationship was observed between the weight of collected prostatic tissue and the wet weight of prostate gland specimen [y = 3.245 x -6.475 (t=15.097, P=0.000)]. It is concluded that under the simulated conditions of transurethral vaporesection of the prostate by 2-mum laser, the vaporization ratio of prostatic tissue can be calculated on the basis of the weight of collected prostatic tissue, and thereby the clearance of prostatic tissue during the formal operation by 2

  2. Kinetics of laser chemical vapor deposition of carbon and refractory metals

    NASA Astrophysics Data System (ADS)

    Gao, Feng

    2000-10-01

    Three-dimensional laser chemical vapor deposition (3D-LCVD) has been used to grow rods of carbon, tungsten, titanium, and hafnium from a variety of hydrocarbons and metal halide-based precursors. A novel computerized 3D-LCVD system was designed and successfully used in the experiments. A focused Nd:Yag laser beam (lambda = 1.06 mum) was utilized to locally heat up a substrate to deposition temperature. The rods, which grew along the axis of the laser beam, had a typical diameter of 30--80 mum and a length of about 1 mm. The precursors for carbon deposition were the alkynes: propyne, butyne, pentyne, hexyne, and octyne. Propyne gave the highest deposition rate, in excess 3 mm/s at high laser powers (0.45 W) and high partial pressures (3000 mbar). the temperature dependence and pressure dependence were both non-linear functions of the growth rate. the temperature dependence could be separated into two regions---the kinetically limited region, which obeys the Arrhenius relationship, and the transport limited region, which is explained by diffusion of the precursors to the reaction zone. The pressure dependence showed that the reaction order for the different precursors varied from 2.5 for propyne to 1.3 for octyne. The precursors used deposit the refractory metals were tungsten hexafloride, titanium tetraiodide and hafnium chloride. The only successful precursor was tungsten hexafluoride, which readily produced tungsten rods when mixed with hydrogen. Rod diameters typically ranged from 50 mum to 400 mum and the average length of the rods were about 1 mm. Much lower deposition rates, less than 4.5 mum/s were obtained in this case as compared to carbon deposition. By an optimization of the LCVD process, it was possible to deposit high-quality single crystal tungsten rods. They were all oriented in the <100> direction.

  3. Method for removing metal vapor from gas streams

    DOEpatents

    Ahluwalia, R.K.; Im, K.H.

    1996-04-02

    A process for cleaning an inert gas contaminated with a metallic vapor, such as cadmium, involves withdrawing gas containing the metallic contaminant from a gas atmosphere of high purity argon; passing the gas containing the metallic contaminant to a mass transfer unit having a plurality of hot gas channels separated by a plurality of coolant gas channels; cooling the contaminated gas as it flows upward through the mass transfer unit to cause contaminated gas vapor to condense on the gas channel walls; regenerating the gas channels of the mass transfer unit; and, returning the cleaned gas to the gas atmosphere of high purity argon. The condensing of the contaminant-containing vapor occurs while suppressing contaminant particulate formation, and is promoted by providing a sufficient amount of surface area in the mass transfer unit to cause the vapor to condense and relieve supersaturation buildup such that contaminant particulates are not formed. Condensation of the contaminant is prevented on supply and return lines in which the contaminant containing gas is withdrawn and returned from and to the electrorefiner and mass transfer unit by heating and insulating the supply and return lines. 13 figs.

  4. Method for removing metal vapor from gas streams

    DOEpatents

    Ahluwalia, R. K.; Im, K. H.

    1996-01-01

    A process for cleaning an inert gas contaminated with a metallic vapor, such as cadmium, involves withdrawing gas containing the metallic contaminant from a gas atmosphere of high purity argon; passing the gas containing the metallic contaminant to a mass transfer unit having a plurality of hot gas channels separated by a plurality of coolant gas channels; cooling the contaminated gas as it flows upward through the mass transfer unit to cause contaminated gas vapor to condense on the gas channel walls; regenerating the gas channels of the mass transfer unit; and, returning the cleaned gas to the gas atmosphere of high purity argon. The condensing of the contaminant-containing vapor occurs while suppressing contaminant particulate formation, and is promoted by providing a sufficient amount of surface area in the mass transfer unit to cause the vapor to condense and relieve supersaturation buildup such that contaminant particulates are not formed. Condensation of the contaminant is prevented on supply and return lines in which the contaminant containing gas is withdrawn and returned from and to the electrorefiner and mass transfer unit by heating and insulating the supply and return lines.

  5. EPA Method 245.1: Determination of Mercury in Water by Cold Vapor Atomic Absorption Spectrometry

    EPA Pesticide Factsheets

    SAM lists this method for preparation and analysis of aqueous liquid and drinking water samples. This method will determine mercuric chloride and methoxyethylmercuric acetate as total mercury using cold vapor atomic absorption spectrometry.

  6. Nonresonant femtosecond laser vaporization with electrospray postionization for ex vivo plant tissue typing using compressive linear classification.

    PubMed

    Judge, Elizabeth J; Brady, John J; Barbano, Paolo Emilio; Levis, Robert J

    2011-03-15

    Laser electrospray mass spectrometry (LEMS) with offline classification is used to discriminate plant tissues at atmospheric pressure using an intense (10(13) W cm(-2)), nonresonant (800 nm) femtosecond laser pulse to vaporize cellular content for subsequent mass analysis. The tissue content of the plant within the 0.05 mm(2) laser interaction region is vaporized into the electrospray plume where the molecules are ionized prior to transfer into the mass spectrometer. The measurements for a flower petal, leaf, and stem of an impatiens plant reveal mass spectral signatures that enable discrimination as performed using a compressive linear classifier. The statistical analysis of the plant tissue samples reveals reproducibility of the data for replicate tissue samples and within a single tissue sample. A similar degree of discrimination was achieved for the green and white regions of aphelandra squarrosa (zebra plant) leaves.

  7. Method for splitting low power laser beams

    SciTech Connect

    Pierscionek, B.K. )

    1990-04-01

    A new method for producing parallel rays from a laser beam using a cylindrical lens and pinholes is presented. This method can produce a greater number of emergent rays than using a {ital beam} {ital splitter}.

  8. Primary Vaginal Adenocarcinoma Arising in Vaginal Adenosis After CO2 Laser Vaporization and 5-Fluorouracil Therapy

    PubMed Central

    Paczos, Tamera A.; Ackers, Stacey; Odunsi, Kunle; Lele, Shashikant; Mhawech-Fauceglia, Paulette

    2016-01-01

    Summary We present a case of a 45-year-old woman with a long-standing history of persistent cervical dysplasia that resulted in a hysterectomy. Subsequent vaginal smears revealed high-grade vaginal intraepithelial neoplasia (VAIN III) on Pap smear with positive human papilloma virus (HPV) testing. Over the course of 2 years, the patient underwent 2 CO2 laser vaporization procedures of the upper vagina and intermittent 5-fluorouracil therapy. A biopsy performed at the time of the second laser procedure revealed endocervical-type well-differentiated adenocarcinoma, associated with VAIN III. HPV in situ hybridization for HPV types 16 and 18 was positive in both the glandular and squamous mucosa. The patient has no known history of intrauterine diethylstilbestrol exposure or mullerian developmental abnormalities. Subsequently, the patient underwent a radical upper vaginetcomy with bilateral pelvic lymph nodes dissection and bilateral salpingo-oophorectomy. The vaginectomy specimen showed residual adenocarcinoma associated with VAIN-III and extensive vaginal adenosis with free resection margins. This is the second reported case in the literature of adenocarcinoma arising in vaginal adenosis after 5-fluorouracil. Herein, we highlight these important findings and shed some light on the pathogenesis of vaginal adenosis and the subsequent development of vaginal adenocarcinoma. PMID:20173507

  9. Primary vaginal adenocarcinoma arising in vaginal adenosis after CO2 laser vaporization and 5-fluorouracil therapy.

    PubMed

    Paczos, Tamera A; Ackers, Stacey; Odunsi, Kunle; Lele, Shashikant; Mhawech-Fauceglia, Paulette

    2010-03-01

    We present a case of a 45-year-old woman with a long-standing history of persistent cervical dysplasia that resulted in a hysterectomy. Subsequent vaginal smears revealed high-grade vaginal intraepithelial neoplasia (VAIN III) on Pap smear with positive human papilloma virus (HPV) testing. Over the course of 2 years, the patient underwent 2 CO(2) laser vaporization procedures of the upper vagina and intermittent 5-fluorouracil therapy. A biopsy performed at the time of the second laser procedure revealed endocervical-type well-differentiated adenocarcinoma, associated with VAIN III. HPV in situ hybridization for HPV types 16 and 18 was positive in both the glandular and squamous mucosa. The patient has no known history of intrauterine diethylstilbestrol exposure or mullerian developmental abnormalities. Subsequently, the patient underwent a radical upper vaginetcomy with bilateral pelvic lymph nodes dissection and bilateral salpingo-oophorectomy. The vaginectomy specimen showed residual adenocarcinoma associated with VAIN-III and extensive vaginal adenosis with free resection margins. This is the second reported case in the literature of adenocarcinoma arising in vaginal adenosis after 5-fluorouracil. Herein, we highlight these important findings and shed some light on the pathogenesis of vaginal adenosis and the subsequent development of vaginal adenocarcinoma.

  10. Rapid and Localized Synthesis of Single-Walled Carbon Nanotubes on Flat Surface by Laser-Assisted Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Kasuya, Keigo; Nagato, Keisuke; Jin, Yusuke; Morii, Hiroshi; Ooi, Takeshi; Nakao, Masayuki

    2007-04-01

    The synthesis of single-walled carbon nanotubes (SWNTs) at a controlled position on a flat surface was demonstrated by laser-assisted chemical vapor deposition (CVD). The developed multilayer substrate including an energy-confining layer (ECL) enabled the efficient heating of catalysts on the surface, resulting in the rapid and localized syntheses of SWNTs. Using a Nd:YAG laser as a heat source, we achieved the rapid synthesis with laser irradiation for 1 s and the localized synthesis in an area of approximately 1 μm diameter. In addition, the scanning of the laser irradiation spot at a rate of 1 μm/s enabled the line-patterned synthesis of SWNTs at a linewidth of 2 μm. The resulting synthesis of SWNTs on a flat surface by laser-assisted CVD will lead to the easy and controllable fabrication of SWNT-based nanodevices.

  11. Zirconia nanoparticles prepared by laser vaporization as fillers for dental adhesives.

    PubMed

    Lohbauer, Ulrich; Wagner, Andrea; Belli, Renan; Stoetzel, Christian; Hilpert, Andrea; Kurland, Heinz-Dieter; Grabow, Janet; Müller, Frank A

    2010-12-01

    Zirconia nanoparticles prepared by laser vaporization were incorporated into the primer or into the adhesive of a commercial adhesive system in order to evaluate its effect on bond strength to dentin. Zirconia nanoparticles (20-50nm) were prepared using a particular laser vaporization technique and incorporated into the primer (P) or into the adhesive (A) of the Adper Scotchbond Multi-Purpose (SBMP) system at 5, 10, 15 and 20wt.% by means of mechanical mixing (stirring) and ultrasonication. Control (unfilled) and experimental groups (filled) were applied, according to the manufacturer's instructions, onto flat mid-coronal human dentin. Composite crowns were built up, stored in distilled water for 24h at 37°C and cut into 0.65±0.05mm² beams following a non-trimming microtensile technique. Specimens were fractured in tension using a universal testing machine (Zwick) and examined by scanning electron microscopy for fractographic analysis. Microtensile bond strength (μTBS) data were analyzed using a two-way ANOVA and modified LSD test at α=0.05. Analysis of the nanofiller distribution and ultramorphological characterization of the interface were performed by transmission electron microscopy (TEM). Zirconia nanoparticle incorporation into the primer or into the adhesive of SBMP significantly increased μTBS to dentin. Filler concentration only affected μTBS significantly in the P group. Statistically significant differences between groups P and A occurred only at 20wt.% filler content, with a significantly higher μTBS in group P. TEM micrographs revealed nanoparticle deposition on top of a hybrid layer when incorporated into the primer, whereas they remained dispersed through the adhesive layer in group A. Zirconia nanoparticles incorporation into SBMP increased bond strength to dentin by reinforcing the interface adhesive layer. Nanofiller incorporation into the primer solution showed a tendency of increasing bond strength with increasing concentration. At high

  12. A new direct absorption tunable diode laser spectrometer for high precision measurement of water vapor in the upper troposphere and lower stratosphere

    NASA Astrophysics Data System (ADS)

    Sargent, M. R.; Sayres, D. S.; Smith, J. B.; Witinski, M.; Allen, N. T.; Demusz, J. N.; Rivero, M.; Tuozzolo, C.; Anderson, J. G.

    2013-07-01

    We present a new instrument for the measurement of water vapor in the upper troposphere and lower stratosphere (UT/LS), the Harvard Herriott Hygrometer (HHH). HHH employs a tunable diode near-IR laser to measure water vapor via direct absorption in a Herriott cell. The direct absorption technique provides a direct link between the depth of the observed absorption line and the measured water vapor concentration, which is calculated based on spectroscopic parameters in the HITRAN database. While several other tunable diode laser (TDL) instruments have been used to measure water vapor in the UT/LS, HHH is set apart by its use of an optical cell an order of magnitude smaller than those of other direct absorption TDLs in operation, allowing for a more compact, lightweight instrument. HHH is also unique in its integration into a common duct with the Harvard Lyman-α hygrometer, an independent photo-fragment fluorescence instrument which has been thoroughly validated over 19 years of flight measurements. The instrument was flown for the first time in the Mid-latitude Airborne Cirrus Properties Experiment (MACPEX) on NASA's WB-57 aircraft in spring, 2011, during which it demonstrated in-flight precision of 0.1 ppmv (1 s) with 1-sigma uncertainty of 5% ± 0.7 ppmv. Since the campaign, changes to the instrument have lead to improved accuracy of 5% ± 0.2 ppmv as demonstrated in the laboratory. During MACPEX, HHH successfully measured water vapor at concentrations from 3.5 to 600 ppmv in the upper troposphere and lower stratosphere. HHH and Lyman-α, measuring independently but under the same sampling conditions, agreed on average to within 1% at water vapor mixing ratios above 20 ppmv and to within 0.3 ppmv at lower mixing ratios. HHH also agreed with a number of other in situ water vapor instruments on the WB-57 to within their stated uncertainties, and to within 0.7 ppmv at low water. This agreement constitutes a significant improvement over past in situ comparisons, in

  13. A new direct absorption tunable diode laser spectrometer for high precision measurement of water vapor in the upper troposphere and lower stratosphere.

    PubMed

    Sargent, M R; Sayres, D S; Smith, J B; Witinski, M; Allen, N T; Demusz, J N; Rivero, M; Tuozzolo, C; Anderson, J G

    2013-07-01

    We present a new instrument for the measurement of water vapor in the upper troposphere and lower stratosphere (UT∕LS), the Harvard Herriott Hygrometer (HHH). HHH employs a tunable diode near-IR laser to measure water vapor via direct absorption in a Herriott cell. The direct absorption technique provides a direct link between the depth of the observed absorption line and the measured water vapor concentration, which is calculated based on spectroscopic parameters in the HITRAN database. While several other tunable diode laser (TDL) instruments have been used to measure water vapor in the UT∕LS, HHH is set apart by its use of an optical cell an order of magnitude smaller than those of other direct absorption TDLs in operation, allowing for a more compact, lightweight instrument. HHH is also unique in its integration into a common duct with the Harvard Lyman-α hygrometer, an independent photo-fragment fluorescence instrument which has been thoroughly validated over 19 years of flight measurements. The instrument was flown for the first time in the Mid-latitude Airborne Cirrus Properties Experiment (MACPEX) on NASA's WB-57 aircraft in spring, 2011, during which it demonstrated in-flight precision of 0.1 ppmv (1 s) with 1-sigma uncertainty of 5% ± 0.7 ppmv. Since the campaign, changes to the instrument have lead to improved accuracy of 5% ± 0.2 ppmv as demonstrated in the laboratory. During MACPEX, HHH successfully measured water vapor at concentrations from 3.5 to 600 ppmv in the upper troposphere and lower stratosphere. HHH and Lyman-α, measuring independently but under the same sampling conditions, agreed on average to within 1% at water vapor mixing ratios above 20 ppmv and to within 0.3 ppmv at lower mixing ratios. HHH also agreed with a number of other in situ water vapor instruments on the WB-57 to within their stated uncertainties, and to within 0.7 ppmv at low water. This agreement constitutes a significant improvement over past in situ comparisons

  14. Analysis of Amphiphilic Lipids and Hydrophobic Proteins Using Nonresonant Femtosecond Laser Vaporization with Electrospray Post-Ionization

    NASA Astrophysics Data System (ADS)

    Brady, John J.; Judge, Elizabeth J.; Levis, Robert J.

    2011-04-01

    Amphiphilic lipids and hydrophobic proteins are vaporized at atmospheric pressure using nonresonant 70 femtosecond (fs) laser pulses followed by electrospray post-ionization prior to being transferred into a time-of-flight mass spectrometer for mass analysis. Measurements of molecules on metal and transparent dielectric surfaces indicate that vaporization occurs through a nonthermal mechanism. The molecules analyzed include the lipids 1-monooleoyl-rac-glycerol, 1,2-dihexanoyl- sn-glycero-3-phosphocholine, 1,2-dimyristoyl- sn-glycero-3-phosphocholine, and the hydrophobic proteins gramicidin A, B, and C. Vaporization of lipids from blood and milk are also presented to demonstrate that lipids in complex systems can be transferred intact into the gas phase for mass analysis.

  15. Intra-operative power measurement of laser fibers during photoselective vaporization of the prostate using the 80W-KTP-Greenlight laser

    NASA Astrophysics Data System (ADS)

    Hermanns, Thomas; Sulser, Tullio; Baumgartner, Martin K.; Fatzer, Markus; Rey, Julien M.; Sigrist, Markus W.; Seifert, Hans-Helge

    2008-02-01

    Photoselective vaporization of the Prostate (PVP) using the 80W-Greenlight-PV (R) Laser System (Laserscope (R), San Jose, USA) has been established as a treatment option for patients suffering from obstructive symptoms caused by benign prostatic hyperplasia. However, longer operation time compared to standard trans-urethral resection of the prostate (TURP) and the high costs of the laser fibers are specific problems of this technique. In addition, many clinicians performing PVP complain about a reduced effectiveness of vaporization during treatment. Therefore, power measurement was performed during PVP using the 80W-Greenlight-PV (R) Laser System. Power output was measured at the beginning and also regularly throughout the operation. A total of 40 fibers were investigated in 35 patients. Damage to the tip of the fibers was regularly visible and increased as more energy was supplied. Additionally, in 90% of all fibers a decrease of power output was detectable during the operation. This became pronounced after the application of 200kJ, resulting in an end of lifespan (i.e. 275kJ) median power output of only 20% of the starting value. Corresponding to the clinical observations the impressive damage to the emission window was associated with a substantial decrease of power output during PVP. These observations might explain the impaired vaporization during PVP and a longer operation time compared to conventional TURP. Hence, improvements in the quality of the laser fibers are necessary to advance the efficiency of this promising technology.

  16. Vapor pressure measurements on low-volatility terpenoid compounds by the concatenated gas saturation method.

    PubMed

    Widegren, Jason A; Bruno, Thomas J

    2010-01-01

    The atmospheric oxidation of monoterpenes plays a central role in the formation of secondary organic aerosols (SOAs), which have important effects on the weather and climate. However, models of SOA formation have large uncertainties. One reason for this is that SOA formation depends directly on the vapor pressures of the monoterpene oxidation products, but few vapor pressures have been reported for these compounds. As a result, models of SOA formation have had to rely on estimated values of vapor pressure. To alleviate this problem, we have developed the concatenated gas saturation method, which is a simple, reliable, high-throughput method for measuring the vapor pressures of low-volatility compounds. The concatenated gas saturation method represents a significant advance over traditional gas saturation methods. Instead of a single saturator and trap, the concatenated method uses several pairs of saturators and traps linked in series. Consequently, several measurements of vapor pressure can be made simultaneously, which greatly increases the rate of data collection. It also allows for the simultaneous measurement of a control compound, which is important for ensuring data quality. In this paper we demonstrate the use of the concatenated gas saturation method by determination of the vapor pressures of five monoterpene oxidation products and n-tetradecane (the control compound) over the temperature range 283.15-313.15 K. Over this temperature range, the vapor pressures ranged from about 0.5 Pa to about 70 Pa. The standard molar enthalpies of vaporization or sublimation were determined by use of the Clausius-Clapeyron equation.

  17. Laser-induced vapor nanobubbles for efficient delivery of macromolecules in live cells

    NASA Astrophysics Data System (ADS)

    Xiong, Ranhua; Raemdonck, Koen; Peynshaert, Karen; Lentacker, Ine; De Cock, Ine; Demeester, Jo; De Smedt, Stefaan C.; Skirtach, Andre G.; Braeckmans, Kevin

    2015-03-01

    Macromolecular agents such as nucleic acids and proteins need to be delivered into living cells for therapeutic purposes. Among physical methods to deliver macromolecules across the cell membrane, laser-induced photoporation using plasmonic nanoparticles is a method that is receiving increasing attention in recent years. By irradiating gold nanoparticles bound to the cell membrane with laser light, nanosized membrane pores can be created. Pores are formed by localized heating or by vapour nanobubbles (VNBs) depending on the incident laser energy. Macromolecules in the surrounding cell medium can then diffuse through the transiently formed pores into the cytoplasm. While both heating and VNBs have been reported before for permeabilization of the cell membrane, it remains unclear which of both methods is more efficient in terms of cell loading with minimal cytotoxicity. In this study we report that under condition of a single 7 ns laser pulse VNBs are substantially more efficient for the cytosolic delivery of macromolecules. We conclude that VNB formation is an interesting photoporation mechanism for fast and efficient macromolecular delivery in live cells.

  18. SIMPOL.1: a simple group contribution method for predicting vapor pressures and enthalpies of vaporization of multifunctional organic compounds

    NASA Astrophysics Data System (ADS)

    Pankow, J. F.; Asher, W. E.

    2008-05-01

    The SIMPOL.1 group contribution method is developed for predicting the liquid vapor pressure poL (atm) and enthalpy of vaporization Δ Hvap (kJ mol-1) of organic compounds as functions of temperature (T). For each compound i, the method assumes log10poL,i (T)=∑kνk,ibk(T) where νk,i is the number of groups of type k, and bk (T) is the contribution to log10poL,i (T) by each group of type k. A zeroeth group is included that uses b0 (T) with ν0,i=1 for all i. A total of 30 structural groups are considered: molecular carbon, alkyl hydroxyl, aromatic hydroxyl, alkyl ether, alkyl ring ether, aromatic ether, aldehyde, ketone, carboxylic acid, ester, nitrate, nitro, alkyl amine (primary, secondary, and tertiary), aromatic amine, amide (primary, secondary, and tertiary), peroxide, hydroperoxide, peroxy acid, C=C, carbonylperoxynitrate, nitro-phenol, nitro-ester, aromatic rings, non-aromatic rings, C=C-C=O in a non-aromatic ring, and carbon on the acid-side of an amide. The T dependence in each of the bk (T) is assumed to follow b(T)=B1/T+B2+B3T+B4ln T. Values of the B coefficients are fit using an initial basis set of 272 compounds for which experimentally based functions po L,i=fi (T) are available. The range of vapor pressure considered spans fourteen orders of magnitude. The ability of the initially fitted B coefficients to predict poL values is examined using a test set of 184 compounds and a T range that is as wide as 273.15 to 393.15 K for some compounds. σFIT is defined as the average over all points of the absolute value of the difference between experimental and predicted values of log10poL,i (T). After consideration of σFIT for the test set, the initial basis set and test set compounds are combined, and the B coefficients re-optimized. For all compounds and temperatures, σFIT=0.34: on average, poL,i (T) values are predicted to within a factor of 2. Because d(log10 poL,i (T))d(1/T) is related to the enthalpy of vaporization ΔHvap,i, the fitted B provide

  19. SIMPOL.1: A simple group contribution method for predicting vapor pressures and enthalpies of vaporization of multifunctional organic compounds

    NASA Astrophysics Data System (ADS)

    Pankow, J. F.; Asher, W. E.

    2007-08-01

    The SIMPOL.1 group contribution method is developed for predicting the liquid vapor pressure pLo (atm) and enthalpy of vaporization ΔHvap (kJ mol-1) of organic compounds as functions of temperature (T). For each compound i, the method assumes log10pL,io(T)=Σkνk,ibk(T) where νk,i is the number of groups of type k, and bk(T) is the contribution to log10 pL,io(T) by each group of type k. A zeroeth group is included that uses b0(T) with ν0,i=1 for all i. A total of 30 structural groups are considered: molecular carbon, alkyl hydroxyl, aromatic hydroxyl, alkyl ether, alkyl ring ether, aromatic ether, aldehyde, ketone, carboxylic acid, ester, nitrate, nitro, alkyl amine (primary, secondary, and tertiary), aromatic amine, amide (primary, secondary, and tertiary), peroxide, hydroperoxide, peroxy acid, C=C, carbonylperoxynitrate, nitro-phenol, nitro-ester, aromatic rings, non-aromatic rings, C=C-C=O in a non-aromatic ring, and carbon on the acid-side of an amide. The T dependence in each of the bk(T) is assumed to follow b(T)=B1/T+B2+B3T+B4lnT. Values of the B coefficients are fit using an initial basis set of 272 compounds for which experimentally based functions pL,io=fi(T) are available. The range of vapor pressure considered spans fourteen orders of magnitude. The ability of the initially fitted B coefficients to predict pLo values is examined using a test set of 161 compounds and a T range that is as wide as 273.15 to 393.15 K for some compounds. σFIT is defined as the average over all points of the absolute value of the difference between experimental and predicted values of log10pL,io(T). After consideration of σFIT for the test set, the initial basis set and test set compounds are combined, and the B coefficients re-optimized. For all compounds and temperatures, σFIT=0.34: on average, pL,io(T) values are predicted to within a factor of 2. Because d(log10pL,io(T))/d(1/T) is related to the enthalpy of vaporization ΔHvap,i, the fitted B provide predictions of

  20. Optical coatings of variable refractive index and high laser-resistance from physical-vapor-deposited perfluorinated amorphous polymer

    DOEpatents

    Chow, Robert; Loomis, Gary E.; Thomas, Ian M.

    1999-01-01

    Variable index optical single-layers, optical multilayer, and laser-resistant coatings were made from a perfluorinated amorphous polymer material by physical vapor deposition. This was accomplished by physically vapor depositing a polymer material, such as bulk Teflon AF2400, for example, to form thin layers that have a very low refractive index (.about.1.10-1.31) and are highly transparent from the ultra-violet through the near infrared regime, and maintain the low refractive index of the bulk material. The refractive index can be varied by simply varying one process parameter, either the deposition rate or the substrate temperature. The thus forming coatings may be utilized in anti-reflectors and graded anti-reflection coatings, as well as in optical layers for laser-resistant coatings at optical wavelengths of less than about 2000 nm.

  1. Optical coatings of variable refractive index and high laser-resistance from physical-vapor-deposited perfluorinated amorphous polymer

    DOEpatents

    Chow, R.; Loomis, G.E.; Thomas, I.M.

    1999-03-16

    Variable index optical single-layers, optical multilayer, and laser-resistant coatings were made from a perfluorinated amorphous polymer material by physical vapor deposition. This was accomplished by physically vapor depositing a polymer material, such as bulk Teflon AF2400, for example, to form thin layers that have a very low refractive index (ca. 1.10--1.31) and are highly transparent from the ultra-violet through the near infrared regime, and maintain the low refractive index of the bulk material. The refractive index can be varied by simply varying one process parameter, either the deposition rate or the substrate temperature. The thus forming coatings may be utilized in anti-reflectors and graded anti-reflection coatings, as well as in optical layers for laser-resistant coatings at optical wavelengths of less than about 2000 nm. 2 figs.

  2. Stable and efficient operation of a large-bore copper vapor laser with funnel-shaped, grooved copper electrodes

    NASA Astrophysics Data System (ADS)

    Sadighi-Bonabi, R.; Pasandideh, K.; Zand, M.; Nazari Mahroo, H.

    2017-03-01

    Using an appropriate design of electrodes and adjustment of the thyratron decoupling circuit as a high-repetition-rate and high-voltage switch, very stable operation of a copper vapor laser at high pressures was obtained. This was achieved by canceling the intense filamentation in the laser plasma at the higher pressures. The transverse grooves on the inner surface of the funnel-shaped copper electrodes permit operation of the laser up to 100 torr. This design reduces the cathode-fall voltage, and as a result reduces the thermal loading in the cathode-fall region. The optimum pressure was 80 torr. At this condition the output power was more than that observed with expensive molybdenum electrodes in a similar laser system.

  3. Growth of thick GaN layers on laser-processed sapphire substrate by hydride vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Koyama, Koji; Aida, Hideo; Kim, Seong-Woo; Ikejiri, Kenjiro; Doi, Toshiro; Yamazaki, Tsutomu

    2014-10-01

    A 600 μm thick GaN layer was successfully grown by hydride vapor phase epitaxy by replacing the standard sapphire substrate with that processed by a focused laser beam within the substrate. The effects of the laser processing on the curvature and cracking of the GaN layer were investigated. Microscopic observations of the interior of the thick GaN layer revealed that the laser-processed substrate suppressed the generation of microcracks in the GaN layer. In addition, the laser processing was also found to reduce the change in the curvature during the GaN layer growth in comparison to that on the standard substrate. It is shown that the overlapping microcracks observed in the GaN layer on the standard sapphire substrate lead to serious cracking after thick GaN layer growth.

  4. Determination of Optimal Vapor Pressure Data by the Second and Third Law Methods

    PubMed Central

    Nakajima, Kunihisa

    2016-01-01

    Though equilibrium vapor pressures are utilized to determine thermodynamic properties of not only gaseous species but also condensed phases, the obtained data often disagree by a factor of 100 and more. A new data analysis method is proposed using the so-called second and third law procedures to improve accuracy of vapor pressure measurements. It was found from examination of vapor pressures of cesium metaborate and silver that the analysis of the difference between the second and third law values can result in determination of an optimal data set. Since the new thermodynamic method does not require special techniques and or experiences in dealing with measured data, it is reliable and versatile to improve the accuracy of vapor pressure evaluation. PMID:28101442

  5. Determination of Optimal Vapor Pressure Data by the Second and Third Law Methods.

    PubMed

    Nakajima, Kunihisa

    2016-01-01

    Though equilibrium vapor pressures are utilized to determine thermodynamic properties of not only gaseous species but also condensed phases, the obtained data often disagree by a factor of 100 and more. A new data analysis method is proposed using the so-called second and third law procedures to improve accuracy of vapor pressure measurements. It was found from examination of vapor pressures of cesium metaborate and silver that the analysis of the difference between the second and third law values can result in determination of an optimal data set. Since the new thermodynamic method does not require special techniques and or experiences in dealing with measured data, it is reliable and versatile to improve the accuracy of vapor pressure evaluation.

  6. Laser-drilled micro-hole arrays on polyurethane synthetic leather for improvement of water vapor permeability

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Wang, A. H.; Zheng, R. R.; Tang, H. Q.; Qi, X. Y.; Ye, B.

    2014-06-01

    Three kinds of lasers at 1064, 532 and 355 nm wavelengths respectively were adopted to construct micro-hole arrays on polyurethane (PU) synthetic leather with an aim to improve water vapor permeability (WVP) of PU synthetic leather. The morphology of the laser-drilled micro-holes was observed to optimize laser parameters. The WVP and slit tear resistance of the laser-drilled leather were measured. Results show that the optimized pulse energy for the 1064, 532 and 355 nm lasers are 0.8, 1.1 and 0.26 mJ, respectively. The diameters of the micro-holes drilled with the optimized laser pulse energy were about 20, 15 and 10 μm, respectively. The depths of the micro-holes drilled with the optimized pulse energy were about 21, 60 and 69 μm, respectively. Compared with the untreated samples, the highest WVP growth ratio was 38.4%, 46.8% and 53.5% achieved by the 1064, 532 and 355 nm lasers, respectively. And the highest decreasing ratio of slit tear resistance was 11.1%, 14.8%, and 22.5% treated by the 1064, 532 and 355 nm lasers, respectively. Analysis of the interaction mechanism between laser beams at three kinds of laser wavelengths and the PU synthetic leather revealed that laser micro-drilling at 355 nm wavelength displayed both photochemical ablation and photothermal ablation, while laser micro-drilling at 1064 and 532 nm wavelengths leaded to photothermal ablation only.

  7. Experimental investigation on a diode-pumped cesium-vapor laser stably operated at continuous-wave and pulse regime.

    PubMed

    Chen, Fei; Xu, Dongdong; Gao, Fei; Zheng, Changbin; Zhang, Kuo; He, Yang; Wang, Chunrui; Guo, Jin

    2015-05-04

    Employing a fiber-coupled diode-laser with a center wavelength of 852.25 nm and a line width of 0.17 nm, experimental investigation on diode-end-pumped cesium (Cs) vapor laser stably operated at continuous-wave (CW) and pulse regime is carried out. A 5 mm long cesium vapor cell filled with 60 kPa helium and 20 kPa ethane is used as laser medium. Using an output coupler with reflectivity of 48.79%, 1.26 W 894.57 nm CW laser is obtained at an incident pump power of 4.76 W, corresponding an optical-optical efficiency of 26.8% and a slope-efficiency of 28.8%, respectively. The threshold temperature is 67.5 °C. Stable pulsed cesium laser with a maximum average output power of 2.6 W is obtained at a repetition rate of 76 Hz, and the pulse repetition rate can be extend to 1 kHz with a pulse width of 18 μs.

  8. MW Spectroscopy Coupled with Ultrafast UV Laser Vaporization: Succinic Acid in the Gas Phase

    NASA Astrophysics Data System (ADS)

    Mendez, Estibaliz; Ecija, Patricia; Cocinero, Emilio J.; Castano, Fernando; Basterretxea, Francisco J.; Godfrey, Peter D.; McNaughton, Don; Jahn, Michaela K.; Nair, K. P. Rajappan; Grabow, Jens-Uwe

    2013-06-01

    Recent lab and field measurements have indicated critical roles of organic acids in enhancing new atmospheric aerosol formation. In order to understand the nucleation process, here we report an experimental and theoretical investigation of chemical structure of succinic acid. We have used the technique of Fourier Transform Microwave Spectroscopy (FTMW). Succinic acid was vaporized by UV ultrafast laser ablation to suppress thermal decomposition processes^a and seeded into an expanding stream of Ne forming a supersonic jet. The rotational spectrum detected the presence of a single most stable conformation in the cm- mm- wave regions for which accurate rotational and centrifugal distortion parameters have been determined. The study was extended to all monosubstituted isotopic species (^{13}C, ^{18}O, D(O)), which were positively identified, leading to an accurate determination of the effective and substitution structures of the molecule. The experimental study was supplemented by ab initio (MP2) and DFT (M06-2X and B3LYP) calculations. ^{a} E. J. Cocinero, A. Lesarri, P. écija, F. J. Basterretxea, J. U. Grabow, J. A. Fernández and F. Castaño, Angew. Chem. Int. Ed., 51, 3119-3124, 2012.

  9. Vapor and Gas-Bubble Growth Dynamics around Laser-Irradiated, Water-Immersed Plasmonic Nanoparticles.

    PubMed

    Wang, Yuliang; Zaytsev, Mikhail E; The, Hai Le; Eijkel, Jan C T; Zandvliet, Harold J W; Zhang, Xuehua; Lohse, Detlef

    2017-02-28

    Microbubbles produced by exposing water-immersed metallic nanoparticles to resonant light play an important role in emerging and efficient plasmonic-enhanced processes for catalytic conversion, solar energy harvesting, biomedical imaging, and cancer therapy. How do these bubbles form, and what is their gas composition? In this paper, the growth dynamics of nucleating bubbles around laser-irradiated, water-immersed Au plasmonic nanoparticles are studied to determine the exact origin of the occurrence and growth of these bubbles. The microbubbles' contact angle, footprint diameter, and radius of curvature were measured in air-equilibrated water (AEW) and degassed water (DGW) with fast imaging. Our experimental data reveals that the growth dynamics can be divided into two regimes: an initial bubble nucleation phase (regime I, < 10 ms) and, subsequently a bubble growth phase (regime II). The explosive growth in regime I is identical for AEW and DGW due to the vaporization of water. However, the slower growth in regime II is distinctly different for AEW and DGW, which is attributed to the uptake of dissolved gas expelled from the water around the hot nanoparticle. Our scaling analysis reveals that the bubble radius scales with time as R(t) ∝ t(1/6) for both AEW and DGW in the initial regime I, whereas in the later regime II it scales as R(t) ∝ t(1/3) for AEW and is constant for perfectly degassed water. These scaling relations are consistent with the experiments.

  10. Spectroscopically pure metal vapor source for highly charged ion spectroscopy and capillary discharge soft x-ray lasers.

    PubMed

    Tomasel, F G; Shlyaptsev, V N; Rocca, J J

    2008-01-01

    We describe a compact, pulsed metal vapor source used for the production of dense plasma columns of interest for both soft x-ray laser research and spectroscopy of highly ionized plasmas. The source generates spectroscopically pure cadmium vapor jets in a room-temperature environment by rapidly heating an electrode with a capacitive discharge. In the configuration described herein, the metal vapor jet produced by the source is axially injected into a fast (up to 15 kA/ ns), high current (up to 200 kA peak) capillary discharge to generate highly ionized cadmium plasma columns. Spectroscopic analysis of the discharge emission in the 12-25 nm spectral range evidences the dominance of Cu-like (CdXX) and Ni-like (CdXXI) lines and shows strong line emission at 13.2 nm from the 4d (1)S(0)-4p (1)P(1) laser transition of Ni-like Cd. Hydrodynamic/atomic physics simulations performed to describe the dynamics of the plasma column and compute the optimum discharge conditions for laser amplification are discussed.

  11. Reinjection laser oscillator and method

    DOEpatents

    McLellan, Edward J.

    1984-01-01

    A uv preionized CO.sub.2 oscillator with integral four-pass amplifier capable of providing 1 to 5 GW laser pulses with pulse widths from 0.1 to 0.5 ns full width at half-maximum (FWHM) is described. The apparatus is operated at any pressure from 1 atm to 10 atm without the necessity of complex high voltage electronics. The reinjection technique employed gives rise to a compact, efficient system that is particularly immune to alignment instabilities with a minimal amount of hardware and complexity.

  12. Comparison of Photoselective Vaporization versus Holmium Laser Enucleation for Treatment of Benign Prostate Hyperplasia in a Small Prostate Volume

    PubMed Central

    Kim, Kang Sup; Choi, Jin Bong; Bae, Woong Jin; Kim, Su Jin; Cho, Hyuk Jin; Hong, Sung-Hoo; Lee, Ji Youl; Kim, Sang Hoon; Kim, Hyun Woo; Cho, Su Yeon; Kim, Sae Woong

    2016-01-01

    Objective Photoselective vaporization of the prostate (PVP) using GreenLight and Holmium laser enucleation of the prostate (HoLEP) is an important surgical technique for management of benign prostate hyperplasia (BPH). We aimed to compare the effectiveness and safety of PVP using a 120 W GreenLight laser with HoLEP in a small prostate volume. Methods Patients who underwent PVP or HoLEP surgery for BPH at our institutions were reviewed from May 2009 to December 2014 in this retrospective study. Among them, patients with prostate volumes < 40 mL based on preoperative trans-rectal ultrasonography were included in this study. Peri-operative and post-operative parameters—such as International Prostate Symptom Score (IPSS), quality of life (QoL), maximum urinary flow rate (Qmax), post-void residual urine volume (PVR), and complications—were compared between the groups. Results PVP was performed in 176 patients and HoLEP in162 patients. Preoperative demographic data were similar in both groups, with the exception of PVR. Operative time and catheter duration did not show significant difference. Significant improvements compared to preoperative values were verified at the postoperative evaluation in both groups in terms of IPSS, QoL, Qmax, and PVR. Comparison of the postoperative parameters between the PVP and HoLEP groups demonstrated no significant difference, with the exception of IPSS voiding subscore at 1 month postoperatively (5.9 vs. 3.8, P< 0.001). There was no significant difference in postoperative complications between the two groups. Conclusion Our data suggest that PVP and HoLEP are efficient and safe surgical treatment options for patients with small prostate volume. PMID:27227564

  13. CO oxidation activity of Cu-CeO2 nano-composite catalysts prepared by laser vaporization and controlled condensation

    NASA Astrophysics Data System (ADS)

    Sundar, Rangaraj S.; Deevi, Sarojini

    2006-08-01

    Ceria supported copper catalysts were synthesized by laser vaporization and controlled condensation method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDAX) and temperature programmed reduction (TPR). The catalytic activity of the nanopowders for CO oxidation reaction was tested in a fixed bed flow tube reactor in Ar-20%O2-4%CO mixture. Irrespective of the copper content, the catalytic activity of the nanopowders is similar in the initial CO test, and the catalytic activity improves (i.e. the light-off temperature decreases) during a subsequent run. The lowest light-off temperature during the second run is recorded in the material with 20% copper. TEM studies on 20%Cu-CeO2 sample in the as-prepared condition and after CO test exhibit two types of ceria particles namely, polygonal particles 3-5 nm in size and spherical particles of 15-20 nm in size. Rapid cooling of the nanoparticles formed during the laser ablation results in incorporation of a large amount of copper within the ceria as solid solution. Presence of solid solution of copper is confirmed by EDAX and electron diffraction analyses. In addition, copper-rich surface layer of Cu2O is found over the spherical particles. The cerium oxide components are essentially identical before and after CO test, except that the polygonal CeO2 particles contain newly formed fine crystals of CuO. TPR results reveal two reduction peaks, which further supports, the presence of two different copper species in the material. The shift in light-off temperature during the second run is attributed to the synergistic interaction between newly formed CuO crystals with the CeO2 matrix.

  14. Method for forming electrically charged laser targets

    DOEpatents

    Goodman, Ronald K.; Hunt, Angus L.

    1979-01-01

    Electrically chargeable laser targets and method for forming such charged targets in order to improve their guidance along a predetermined desired trajectory. This is accomplished by the incorporation of a small amount of an additive to the target material which will increase the electrical conductivity thereof, and thereby enhance the charge placed upon the target material for guidance thereof by electrostatic or magnetic steering mechanisms, without adversely affecting the target when illuminated by laser energy.

  15. Simple Method To Measure the Vapor Pressure of Phthalates and Their Alternatives.

    PubMed

    Wu, Yaoxing; Eichler, Clara M A; Chen, Shengyang; Little, John C

    2016-09-20

    Phthalates and alternative plasticizers are semivolatile organic compounds (SVOCs), an important class of indoor pollutants that may have significant adverse effects on human health. Unfortunately, models that predict emissions of and the resulting exposure to SVOCs have substantial uncertainties. One reason is that the characteristics governing emissions, transport, and exposure are usually strongly dependent on vapor pressure. Furthermore, available data for phthalates exhibit significant variability, and vapor pressures for the various alternatives are usually unavailable. For these reasons, a new approach based on modeling of the evaporation process was developed to determine vapor pressures of phthalates and alternate plasticizers. A laminar flow forced convection model was used in the design of a partial saturator (PS) tube. The mass transfer mechanisms in the PS tube are accurately modeled and enable the determination of vapor pressure even when the carrier gas is not completely saturated, avoiding the complicated procedure to establish vapor saturation. The measured vapor pressures ranged from about 10(-2) to 10(-7) Pa. Compared to the traditional gas saturation method, the model-based approach is advantageous in terms of both predictability and simplicity. The knowledge provides new insight into experimental design and a sound basis for further method development.

  16. In situ metalorganic vapor phase epitaxy control of GaAs/AlAs Bragg reflectors by laser reflectometry at 514 nm

    NASA Astrophysics Data System (ADS)

    Raffle, Y.; Kuszelewicz, R.; Azoulay, R.; Le Roux, G.; Michel, J. C.; Dugrand, L.; Toussaere, E.

    1993-12-01

    In situ reflectometry with a 514-nm laser beam was used to monitor AlAs and GaAs layer thicknesses grown by metalorganic vapor phase epitaxy. The effective optical indices of these materials have been calibrated at the growth temperature by using an original method based on ex situ double crystal x-ray diffraction measurement. According to these measured indices, the in situ laser reflectometry at 514 nm appears to be well suited for a real-time thickness control of the GaAs/AlAs based Bragg reflectors. Finally, Bragg reflectors centered at 980 nm have been grown using the reflectometry at 514 nm. X-ray diffraction and reflectivity measurements performed on these reflectors confirm a 1% reproducibility and accuracy of the wavelength stop band center.

  17. Research remote laser methods for radionuclides monitoring

    NASA Astrophysics Data System (ADS)

    Kascheev, S. V.; Elizarov, Valentin V.; Grishkanich, Alexander S.; Bespalov, V. G.; Vasil'ev, Sergey K.; Zhevlakov, A. P.

    2014-05-01

    Laser sensing can serve as a highly effective method of searching and monitoring of radioactive contamination. The first method is essence consists in definition the Sr90 and Сs137 concentration by excitation and registration of fluorescence at wavelength of λ = 0.347÷7.0 μm at laser sounding. The second method experiments were carried out under the Raman-scattering circuit. Preliminary results of investigation show the real possibility to register of leakage of a radionuclide with concentration at level of 108÷109 сm-3 on a safe distance from the infected object.

  18. A review-application of physical vapor deposition (PVD) and related methods in the textile industry

    NASA Astrophysics Data System (ADS)

    Shahidi, Sheila; Moazzenchi, Bahareh; Ghoranneviss, Mahmood

    2015-09-01

    Physical vapor deposition (PVD) is a coating process in which thin films are deposited by the condensation of a vaporized form of the desired film material onto the substrate. The PVD process is carried out in a vacuum. PVD processes include different types, such as: cathode arc deposition, electron beam physical vapor deposition, evaporative deposition, sputtering, ion plating and enhanced sputtering. In the PVD method, the solid coating material is evaporated by heat or by bombardment with ions (sputtering). At the same time, a reactive gas is also introduced; it forms a compound with the metal vapor and is deposited on the substrate as a thin film with highly adherent coating. Such coatings are used in a wide range of applications such as aerospace, automotive, surgical, medical, dyes and molds for all manner of material processing, cutting tools, firearms, optics, thin films and textiles. The objective of this work is to give a comprehensive description and review of the science and technology related to physical vapor deposition with particular emphasis on their potential use in the textile industry. Physical vapor deposition has opened up new possibilities in the modification of textile materials and is an exciting prospect for usage in textile design and technical textiles. The basic principle of PVD is explained and the major applications, particularly sputter coatings in the modification and functionalization of textiles, are introduced in this research.

  19. Vapor pressure measurements by mass loss transpiration method with a thermogravimetric apparatus.

    PubMed

    Viswanathan, R; Narasimhan, T S Lakshmi; Nalini, S

    2009-06-18

    Thermobalances are used for equilibrium vapor pressure measurements based on both effusion and transpiration methods. In the case of the transpiration method, however, despite the numerous advantages a thermogravimetric apparatus can offer, it is not as widely used as is the conventional apparatus. In this paper, the difference that can exist in the vapor phase compositions in an effusion cell and in a transpiration cell is shown first with two examples. Subsequently, how a commercial thermobalance was utilized to perform transpiration experiments that conform to the basic principle of the transpiration method and yield vapor pressures consistent with the Knudsen effusion mass spectrometric method is described. The three systems investigated are CsI(s), TeO(2)(s), and Te(s), each known to vaporize congruently, but in different manner. A critical analysis was performed on the information available in the literature on transpiration measurements using thermogravimetric apparatuses, and the salient findings are discussed. Smaller plateau regions than with conventional transpiration apparatuses and the lack of evidence for perfect transpiration conditions in some transpiration thermogravimetric investigations are shown with a few examples. A recommendation is made for the use of the rate of mass loss versus flow rate plot to ascertain that the usual apparent vapor pressure versus flow rate plot corresponds to a meaningful transpiration experiment.

  20. Study of Doped ZnO Films Synthesized by Combining Vapor Gases and Pulsed Laser Deposition

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, Ching-Hua; Lehoczky, Sandor L.; George, M. A.

    2000-01-01

    The properties and structure of the ZnO material are similar to those of the GaN. Since an excitonic binding energy of ZnO is about 60 meV, it has strong potential for excitonic lasing at the room temperature. This makes synthesizing ZnO films for applications attractive. However, there are several hurdles in fabricating electro-optical devices from ZnO. One of those is in growing doped p-type ZnO films. Although techniques have been developed for the doping of both p-type and n-type ZnO, this remains an area that can be improved. In this presentation, we will report the experimental results of using both thermal vapor and pulsed laser deposition to grow doped ZnO films. The films are deposited on (0001) sapphire, (001) Si and quartz substrates by ablating a ZnO target. The group III and V elements are introduced into the growth chamber using inner gases. Films are characterized by x-ray diffraction, scanning probe microscopy, energy dispersive spectroscopy, Auger electron spectroscopy, and electrical measurements. The full width at half maximum of theta rocking curves for epitaxial films is less than 0.5 deg. In textured films, it rises to several degrees. Film surface morphology reveals an island growth pattern, but the size and density of these islands vary with the composition of the reactive gases. The electrical resistivity also changes with the doped elements. The relationship between the doping elements, gas composition, and film properties will be discussed.

  1. Industrial applications of laser methods profilometry

    SciTech Connect

    Doyle, J.L.

    1995-12-31

    Laser-based profilometry has evolved rapidly over the past ten years. During that period, QUEST Integrated Inc. has been actively involved in the development of systems for a wide variety of NDE applications. The measurement method is based on the principle of optical triangulation. The sensor includes a diode laser which generates the collimated laser beam that is projected orthogonally onto a target surface. Receiving optics, positioned at an oblique angle to the beam, image the reflected light onto a lateral-effect photodetector. Depending on the packaging constraints and resolution requirements, probes use either a single or dual-axis lateral-effect photodetector. As the target surface moves toward or away from the laser source, the imaged light moves across the photodetector in a predictable and repeatable manner. Since the laser beam can be focused to a ``footprint`` as small as a few microns in diameter, this method provides unparalleled spatial resolution. In addition, lateral effect photodetectors are composed or a single silicon element that provides almost infinite lateral resolution. This method was applied to two applications in this paper. The first was to locate and identify flows caused by pitting corrosion in steam generator tubes at nuclear power plants. The second was for inspection of gun tubes by the US army.

  2. Investigation on 447.3 nm blue-violet laser by extra-cavity frequency doubling of a diode-pumped cesium vapor laser

    NASA Astrophysics Data System (ADS)

    Xu, Dongdong; Chen, Fei; Guo, Jin; Shao, Mingzhen; Xie, Jijiang

    2016-09-01

    447.3 nm blue-violet lasers are investigated by extra-cavity single-pass second harmonic generation (SHG) of diode-pumped cesium vapor lasers (Cs-DPALs) using a LBO crystal. Two types of 894.6 nm Cs-DPAL are constructed, and the beam quality factors are Mx2=1.02, My2=1.13 and Mx2=2.13, Mx2=2.66, respectively. The maximum output powers for the two types of Cs-DPAL operating in pulsed mode are 0.692 W and 2.6 W, and the corresponding maximum second harmonics (SH) powers are 9.5 μW and 11.2 μW at optimal focusing parameter of 1.68, respectively. The relative insensitivity of SH power to the LBO crystal temperature and the influence of Cs laser beam quality on the SHG efficiency are analyzed qualitatively.

  3. MONITORING METHODS ADAPTABLE TO VAPOR INTRUSION MONITORING - USEPA COMPENDIUM METHODS TO-15, TO-15 SUPPLEMENT (DRAFT), AND TO-17

    EPA Science Inventory

    USEPA ambient air monitoring methods for volatile organic compounds (VOCs) using specially-prepared canisters and solid adsorbents are directly adaptable to monitoring for vapors in the indoor environment. The draft Method TO-15 Supplement, an extension of the USEPA Method TO-15,...

  4. Method of increasing biodegradation of sparingly soluble vapors

    DOEpatents

    Cherry, Robert S.

    2000-01-01

    A method for increasing biodegradation of sparingly soluble volatile organic compounds (VOCs) in a bioreactor is disclosed. The method comprises dissolving in the aqueous phase of the bioreactor a water soluble, nontoxic, non-biodegradable polymer having a molecular weight of at least 500 and operable for decreasing the distribution coefficient of the VOCs. Polyoxyalkylene alkanols are preferred polymers. A method of increasing the growth rate of VOC-degrading microorganisms in the bioreactor and a method of increasing the solubility of sparingly soluble VOCs in aqueous solution are also disclosed.

  5. Theoretical studies of Resonance Enhanced Stimulated Raman Scattering (RESRS) of frequency-doubled Alexandrite laser wavelength in cesium vapor. Progress report, January-June 1987

    SciTech Connect

    Lawandy, N.M.

    1987-01-01

    The solutions for the imaginary susceptibility of the Raman field transition with arbitrary relaxation rates and field strengths are examined for three different sets of relaxation rates. These rates correspond to: (1) Far Infrared (FIR) Raman lasers in the diabatic collision regime without consideration of coupled population decay in a closed system, (2) Raman FIR lasers in the diabatic collision regime with coupled population conserving decay, and (3) IR Raman gain in cesium vapor. The model is further expanded to include Doppler broadening and used to predict the peak gain as a function of detuning for a frequency doubled Alexandrite laser-pumped cesium vapor gain cell.

  6. Method of plasma enhanced chemical vapor deposition of diamond using methanol-based solutions

    NASA Technical Reports Server (NTRS)

    Tzeng, Yonhua (Inventor)

    2009-01-01

    Briefly described, methods of forming diamond are described. A representative method, among others, includes: providing a substrate in a reaction chamber in a non-magnetic-field microwave plasma system; introducing, in the absence of a gas stream, a liquid precursor substantially free of water and containing methanol and at least one carbon and oxygen containing compound having a carbon to oxygen ratio greater than one, into an inlet of the reaction chamber; vaporizing the liquid precursor; and subjecting the vaporized precursor, in the absence of a carrier gas and in the absence in a reactive gas, to a plasma under conditions effective to disassociate the vaporized precursor and promote diamond growth on the substrate in a pressure range from about 70 to 130 Torr.

  7. Influence of the pump-to-laser beam overlap on the performance of optically pumped cesium vapor laser.

    PubMed

    Cohen, Tom; Lebiush, Eyal; Auslender, Ilya; Barmashenko, Boris D; Rosenwaks, Salman

    2016-06-27

    Experimental and theoretical study of the influence of the pump-to-laser beam overlap, a crucial parameter for optimization of optically pumped alkali atom lasers, is reported for Ti:Sapphire pumped Cs laser. Maximum laser power > 370 mW with an optical-to-optical efficiency of 43% and slope efficiency ~55% was obtained. The dependence of the lasing power on the pump power was found for different pump beam radii at constant laser beam radius. Non monotonic dependence of the laser power (optimized over the temperature of the Cs cell) on the pump beam radius was observed with a maximum achieved at the ratio ~0.7 between the pump and laser beam radii. The optimal temperature decreased with increasing pump beam radius. A simple optical model of the laser, where Gaussian spatial shapes of the pump and laser intensities in any cross section of the beams were assumed, was compared to the experiments. Good agreement was obtained between the measured and calculated dependence of the laser power on the pump power at different pump beam radii and also of the laser power, threshold pump power and optimal temperature on the pump beam radius. The model does not use empirical parameters such as mode overlap efficiency and can be applied to different Ti:Sapphire and diode pumped alkali lasers with arbitrary spatial distributions of the pump and laser beam widths.

  8. Progress toward a water-vapor differential absorption lidar (DIAL) using a widely tunable amplified diode laser source

    NASA Astrophysics Data System (ADS)

    Obland, Michael D.; Meng, Lei S.; Repasky, Kevin S.; Shaw, Joseph A.; Carlsten, John L.

    2005-08-01

    Water vapor is one of the most significant constituents of the atmosphere because of its role in cloud formation, precipitation, and interactions with electromagnetic radiation, especially its absorption of longwave infrared radiation. Some details of the role of water vapor and related feedback mechanisms in the Earth system need to be characterized better if local weather, global climate, and the water cycle are to be understood. A Differential Absorption LIDAR (DIAL) with a compact laser diode source may be able to provide boundary-layer water vapor profiles with improved vertical resolution relative to passive remote sensors. While the tradeoff with small DIAL systems is lower vertical resolution relative to large LIDARs, the advantage is that DIAL systems can be built much smaller and more robust at less cost, and consequently are the more ideal choice for creating a multi-point array or satellite-borne system. This paper highlights the progress made at Montana State University towards a water vapor DIAL using a widely tunable amplified external cavity diode laser (ECDL) transmitter. The ECDL is configured in a Littman-Metcalf configuration and was built at Montana State University. It has a continuous wave (cw) output power of 20 mW, a center wavelength of 832 nm, a coarse tuning range of 17 nm, and a continuous tuning range greater than 20 GHz. The ECDL is used to injection seed a tapered amplifier with a cw output power of 500 mW. The spectral characteristics of the ECDL are transferred to the output of the tapered amplifier. The rest of the LIDAR uses commercially available telescopes, filter optics, and detectors. Initial cw and pulsed absorption measurements are presented.

  9. Method for laser induced isotope enrichment

    DOEpatents

    Pronko, Peter P.; Vanrompay, Paul A.; Zhang, Zhiyu

    2004-09-07

    Methods for separating isotopes or chemical species of an element and causing enrichment of a desired isotope or chemical species of an element utilizing laser ablation plasmas to modify or fabricate a material containing such isotopes or chemical species are provided. This invention may be used for a wide variety of materials which contain elements having different isotopes or chemical species.

  10. Apparatus and method for laser velocity interferometry

    DOEpatents

    Stanton, Philip L.; Sweatt, William C.; Crump, Jr., O. B.; Bonzon, Lloyd L.

    1993-09-14

    An apparatus and method for laser velocity interferometry employing a fixed interferometer cavity and delay element. The invention permits rapid construction of interferometers that may be operated by those non-skilled in the art, that have high image quality with no drift or loss of contrast, and that have long-term stability even without shock isolation of the cavity.

  11. Development of Tunable Diode Laser Absorption Tomography for Determination of Spatially Resolved Distributions of Water Vapor Temperature and Concentration

    NASA Astrophysics Data System (ADS)

    Bryner, Elliott

    Optical diagnostic techniques used in high speed, high enthalpy flows, such as in a supersonic ramjet (scramjet) combustor, allow direct measurement of temperature and species concentration. Tunable Diode Laser Absorption Spectroscopy (TDLAS) is a common laser based measurement technique for measuring temperature and species concentration in harsh environments such as chemically reacting flows. TDLAS is a one-dimensional, path integrated measurement that provides average values of the measured quantities and can be affected by gradients in the measurement space. By combining TDLAS with tomographic image reconstruction a two-dimensional spatially resolved distribution can be obtained. This technique is called Tunable Diode Laser Absorption Tomography. TDLAT has been developed for the purpose of making temperature and species concentration measurements on the supersonic combustion facility at the Aerospace Research Laboratory. TDLAT has been developed for the purpose of making two-dimensional measurements of water vapor concentration, which when combined with Stereoscopic Particle Image Velocimetry can be used to calculate supersonic combustion efficiency of a scramjet combustor. This measurement system has been used in measurements of a flat flame burner from which two-dimensional distributions of temperature and water vapor concentration have been calculated. The calculated temperatures were then compared to measurements made on the same flat flame burner. Reconstructions of temperature and concentration show the structure of the flat flame burner, resolving regions of ambient room air, nitrogen co-flow, mixing layer and hot burner core. The TDLAT system was then installed on the supersonic combustion facility, where measurements were made for a known mole fraction of steam injected into the free stream. The TDLAT system was then used to measure water vapor concentration and temperature for clean-air combustion for an equivalence ratio of 0.17. The resulting values

  12. Solid vapor pressure for five heavy PAHs via the Knudsen effusion method.

    PubMed

    Fu, Jinxia; Suuberg, Eric M

    2011-11-01

    Polycyclic aromatic hydrocarbons (PAHs) are compounds resulting from incomplete combustion and many fuel processing operations, and they are commonly found as subsurface environmental contaminants at sites of former manufactured gas plants. Knowledge of their vapor pressures is the key to predict their fate and transport in the environment. The present study involves five heavy PAHs, i.e. benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[ghi]perylene, indeno[1,2,3-cd]pyrene, and dibenz[a,h]anthracene, which are all as priority pollutants classified by the US EPA. The vapor pressures of these heavy PAHs were measured by using Knudsen effusion method over the temperature range of 364 K to 454 K. The corresponding values of the enthalpy of sublimation were calculated from the Clausius-Clapeyron equation. The enthalpy of fusion for the 5 PAHs was also measured by using differential scanning calorimetry and used to convert earlier published sub-cooled liquid vapor pressure data to solid vapor pressure in order to compare with the present results. These adjusted values do not agree with the present measured actual solid vapor pressure values for these PAHs, but there is good agreement between present results and other earlier published sublimation data.

  13. A comparison of incidences of bladder neck contracture of 80- versus 180-W GreenLight laser photoselective vaporization of benign prostatic hyperplasia.

    PubMed

    Hu, Bo; Song, Zhenyu; Liu, Hui; Qiao, Liang; Zhao, Yong; Wang, Muwen; Song, Wei; Zhang, Dong; Jin, Xunbo; Zhang, Haiyang

    2016-11-01

    Bladder neck contracture (BNC) after GreenLight laser photoselective vaporization (PVP) of benign prostatic hyperplasia is a common complication. In the present study, data of patients received 80 or 180 W PVP were collected. Perioperative parameters, including applied energy, irradiation time, catheter removal time, and hospital stay, were recorded. Postoperative parameters, including maximum urinary flow rate, International Prostate Symptom Score, post-void residual volume, and incidences of BNC, were recorded at 3 and 12 months after operations. Bladder neck tissues were taken at 3 months after operations for immunohistochemical staining and western blot analysis to examine the expressions of collagen I, matrix metalloproteinase-3 (MMP-3), and transforming growth factor-β (TGF-β). Sample size of patients was calculated with a power of 80 %. Chi-square test and one-way analysis of variance were performed as statistical methods. Three hundred twenty-six patients who received potassium titanyl phosphate (KTP) laser and 256 who received X-ray photoelectron spectroscopy (XPS) laser entered into the study. Perioperative parameters were comparable, except for shorter irradiation time in 180 W group (P = 0.032). Postoperative parameters were also similar, except for higher incidence of BNC in 80 W group at 3 months after operations (P = 0.022). Immunohistochemical staining and western blot analysis showed higher expressions of collagen I, MMP-3, and TGF-β in 80 W group than in 180 W group. In conclusion, 80 W GreenLight laser showed a comparable efficacy with 180-W laser in PVP but showed a higher incidence of BNC in short term, which might be the result of up-regulated fibrotic factors in bladder neck triggered by lasers.

  14. Materials, methods and devices to detect and quantify water vapor concentrations in an atmosphere

    DOEpatents

    Allendorf, Mark D; Robinson, Alex L

    2014-12-09

    We have demonstrated that a surface acoustic wave (SAW) sensor coated with a nanoporous framework material (NFM) film can perform ultrasensitive water vapor detection at concentrations in air from 0.05 to 12,000 ppmv at 1 atmosphere pressure. The method is extendable to other MEMS-based sensors, such as microcantilevers, or to quartz crystal microbalance sensors. We identify a specific NFM that provides high sensitivity and selectivity to water vapor. However, our approach is generalizable to detection of other species using NFM to provide sensitivity and selectivity.

  15. Retrofit device and method to improve humidity control of vapor compression cooling systems

    DOEpatents

    Roth, Robert Paul; Hahn, David C.; Scaringe, Robert P.

    2016-08-16

    A method and device for improving moisture removal capacity of a vapor compression system is disclosed. The vapor compression system is started up with the evaporator blower initially set to a high speed. A relative humidity in a return air stream is measured with the evaporator blower operating at the high speed. If the measured humidity is above the predetermined high relative humidity value, the evaporator blower speed is reduced from the initially set high speed to the lowest possible speed. The device is a control board connected with the blower and uses a predetermined change in measured relative humidity to control the blower motor speed.

  16. Temporal compression of cw diode-laser output into short pulses with cesium-vapor group-velocity dispersion.

    PubMed

    Choi, K; Menders, J; Ross, D; Korevaar, E

    1993-11-15

    Using a technique similar to chirped pulse compression, we have compressed the 50-mW cw output of a diode laser into pulses of greater than 500-mW peak power and less than 400-ps duration. By applying a small current modulation to the diode, we induced a small wavelength modulation in the vicinity of the 6s(1/2)-to-6p(3/2) cesium resonance transition at 852 nm. Group-velocity dispersion on propagation through a cesium vapor cell then led to pulse compression. We developed a simple model to make predictions of output pulse shapes by using different modulation waveforms.

  17. Subscale Ship Airwake Studies Using Novel Vortex Flow Devices with Smoke, Laser-Vapor-Screen and Particle Image Velocimetry

    NASA Technical Reports Server (NTRS)

    Lamar, John E.; Landman, Drew; Swift, Russell S.; Parikh, Paresh C.

    2007-01-01

    Ships produce vortices and air-wakes while either underway or stationary in a wind. These flow fields can be detrimental to the conduction of air operations in that they can adversely impact the air vehicles and flight crews. There are potential solutions to these problems for both frigates/destroyers and carriers through the use of novel vortex flow or flow control devices. This appendix highlights several devices which may have application and points out that traditional wind-tunnel testing using smoke, laser-vapor screen, and Particle Image Velocimetry can be useful in sorting out the effectiveness of different devices.

  18. Apparatus and method for laser beam diagnosis

    DOEpatents

    Salmon, Jr., Joseph T.

    1991-01-01

    An apparatus and method is disclosed for accurate, real time monitoring of the wavefront curvature of a coherent laser beam. Knowing the curvature, it can be quickly determined whether the laser beam is collimated, or focusing (converging), or de-focusing (diverging). The apparatus includes a lateral interferometer for forming an interference pattern of the laser beam to be diagnosed. The interference pattern is imaged to a spatial light modulator (SLM), whose output is a coherent laser beam having an image of the interference pattern impressed on it. The SLM output is focused to obtain the far-field diffraction pattern. A video camera, such as CCD, monitors the far-field diffraction pattern, and provides an electrical output indicative of the shape of the far-field pattern. Specifically, the far-field pattern comprises a central lobe and side lobes, whose relative positions are indicative of the radius of curvature of the beam. The video camera's electrical output may be provided to a computer which analyzes the data to determine the wavefront curvature of the laser beam.

  19. Apparatus and method for laser beam diagnosis

    DOEpatents

    Salmon, J.T. Jr.

    1991-08-27

    An apparatus and method are disclosed for accurate, real time monitoring of the wavefront curvature of a coherent laser beam. Knowing the curvature, it can be quickly determined whether the laser beam is collimated, or focusing (converging), or de-focusing (diverging). The apparatus includes a lateral interferometer for forming an interference pattern of the laser beam to be diagnosed. The interference pattern is imaged to a spatial light modulator (SLM), whose output is a coherent laser beam having an image of the interference pattern impressed on it. The SLM output is focused to obtain the far-field diffraction pattern. A video camera, such as CCD, monitors the far-field diffraction pattern, and provides an electrical output indicative of the shape of the far-field pattern. Specifically, the far-field pattern comprises a central lobe and side lobes, whose relative positions are indicative of the radius of curvature of the beam. The video camera's electrical output may be provided to a computer which analyzes the data to determine the wavefront curvature of the laser beam. 11 figures.

  20. Repetitive output laser system and method using target reflectivity

    DOEpatents

    Johnson, Roy R.

    1978-01-01

    An improved laser system and method for implosion of a thermonuclear fuel pellet in which that portion of a laser pulse reflected by the target pellet is utilized in the laser system to initiate a succeeding target implosion, and in which the energy stored in the laser system to amplify the initial laser pulse, but not completely absorbed thereby, is used to amplify succeeding laser pulses initiated by target reflection.

  1. The PSDAVLL signal detection with synchronous ferroelectric liquid crystal switching as a laser frequency stabilization method

    NASA Astrophysics Data System (ADS)

    Dudzik, G.; Rzepka, J.; Abramski, K. M.

    2016-12-01

    In this paper we present the DAVLL (Dichroic Atomic Vapor Laser Lock) signals detection method for laser frequency stabilization which has been improved by synchronous detection system based on the surface-stabilized ferroelectric liquid crystal (SSFLC). The SSFLC cell is a polarization switch and quarter waveplate component and it replaces the well-known two-photodiode detection configuration known as the balanced polarimeter. The presented polarization switching dichroic atomic vapor laser lock technique (PSDAVLL) was practically used in VCSEL-based frequency stabilization system with vapor isotopes (85,87Rb) rubidium cell. The applied PSDAVLL method has allowed us to obtain a frequency stability of 2.7 × 10-9 and a reproducibility of 1.2 × 10-8, with a dynamic range ratio (DNR) of detected signals of around 81.4 dB, what is 9.6 dB better than obtained in the balanced polarimeter configuration. The described PSDAVLL technique was compared with 3-f (on the 3rd harmonic) and passive frequency stabilization methods. Additionally, the presented setup consists only one-photodiode detection path what reduces parasitic phenomena like offsets between photodiode amplifiers, amplifier gain changes due to ambient conditions, aging effects of electronic components etc. as a consequence leads to better frequency reproducibility, stabilization accuracy and less detection system sensitivity to ambient condition changes.

  2. Augmented Lagrangian method for optimal laser control

    NASA Astrophysics Data System (ADS)

    Shen, Hai; Dussault, Jean-Pierre; Bandrauk, Andre D.

    1994-06-01

    We use penalty methods derived from Augmented Lagrangians coupled with unitary exponential operator methods to solve the optimal control problem for molecular time-dependent Schodinger equations involving laser pulse excitations. A stable numerical algorithm is presented which propagates directly from initial states to given final states. Results are reported for an analytically solvable model for the complete inversion of a three-state system.

  3. Radioiodination of interleukin 2 to high specific activities by the vapor-phase chloramine T method

    SciTech Connect

    Siekierka, J.J.; DeGudicibus, S.

    1988-08-01

    Recombinant human interleukin 2 (IL-2) was radioiodinated utilizing the vapor phase chloramine T method of iodination. The method is rapid, reproducible, and allows the efficient radioiodination of IL-2 to specific activities higher than those previously attained with full retention of biological activity. IL-2 radioiodinated by this method binds with high affinity to receptors present on phytohemagglutinin-stimulated peripheral blood lymphocytes and should be useful for the study of receptor structure and function.

  4. Water-vapor absorption line measurements in the 940-nm band by using a Raman-shifted dye laser

    NASA Technical Reports Server (NTRS)

    Chu, Zhiping; Wilkerson, Thomas D.; Singh, Upendra N.

    1993-01-01

    We report water-vapor absorption line measurements that are made by using the first Stokes radiation (930-982 nm) with HWHM 0.015/cm generated by a narrow-linewidth, tunable dye laser. Forty-five absorption line strengths are measured with an uncertainty of 6 percent and among them are fourteen strong lines that are compared with previous measurements for the assessment of spectral purity of the light source. Thirty air-broadened linewidths are measured with 8 percent uncertainty at ambient atmospheric pressure with an average of 0.101/cm. The lines are selected for the purpose of temperature-sensitive or temperature-insensitive lidar measurements. Results for these line strengths and linewidths are corrected for broadband radiation and finite laser linewidth broadening effects and compared with the high-resolution transmission molecular absorption.

  5. X-ray laser system, x-ray laser and method

    DOEpatents

    London, Richard A.; Rosen, Mordecai D.; Strauss, Moshe

    1992-01-01

    Disclosed is an x-ray laser system comprising a laser containing generating means for emitting short wave length radiation, and means external to said laser for energizing said generating means, wherein when the laser is in an operative mode emitting radiation, the radiation has a transverse coherence length to width ratio of from about 0.05 to 1. Also disclosed is a method of adjusting the parameters of the laser to achieve the desired coherence length to laser width ratio.

  6. Determination of vaporization enthalpies of the branched esters from correlation gas chromatography and transpiration methods

    SciTech Connect

    Verevkin, S.P.; Heintz, A.

    1999-12-01

    Vaporization enthalpies are indispensable for the assessment of the environmental fate and behavior of environmental contaminants. The temperature dependencies of retention indices of a set of 80 esters with branched molecular structures were measured on a nonpolar gas chromatographic column. The correlation gas chromatography method and reliable data set of 16 esters selected from the literature were used to derive a correlation for the prediction of the standard molar enthalpies of vaporization {Delta}{sub 1}{sup g}H{sub m}{sup {degree}} at the temperature T = 298.15 K. Experimental values of {Delta}{sub 1}{sup g}H{sub m}{sup {degree}} for 64 branched esters were obtained with the help of this correlation. The vaporization enthalpies of isopentyl acetate, ethyl hexanoate, and neopentyl pivalate were additionally obtained by the transpiration method from the temperature dependence of the vapor pressure measured in a flow system and used for checking the validity of the correlation gas chromatography method.

  7. On the prospects of using runaway electron beams generated in an open discharge for the pumping of metal-vapor lasers

    SciTech Connect

    Arlantsev, S.V.; Borovich, B.L.; Yurchenko, N.I.

    1995-03-01

    The excitation of gas lasers with the help of electron beams (e-beams) is, at the present time, one of the most promising methods of pumping. In most of the conventional methods, an electron beam is produced as a result of a collisionless acceleration of electrons due to the low gas density in a diode of an accelerator. Because of this, an accelerative gap should be hermetically isolated from a laser cell, which makes the technique of e-beam injection into the active region quite complicated. A radical solution to the problem would be the production of an e-beam in the gas whose density in the accelerative gap corresponds to the working pressure of the laser. This would allow one to place an accelerator in one chamber with the laser. The generation of a beam in a high-density gas would become possible when one provides the conditions for an effective transition of electrons into the runaway regime. Such a motion of electrons can be achieved in a strong electric field as a result of the decreasing cross section of the electron-atom interaction as sufficiently high energy. The runaway effect is manifested in the case where the electrons moving under the action of a strong external field obtain kinetic energy comparable with the potential difference. The kinetic energy is many times greater than that spent in one collision. Despite the considerable number of collisions, the electrons are transmitted into the steady acceleration regime, and their motion becomes almost directed, thus forming a beam. The present paper is devoted to the development of a physical-mathematical model of an open discharge, the calculation of its characteristics, and the estimation of the potentialities of e-beam pumping of metal-vapor lasers.

  8. Flow speed of the ablation vapors generated during laser drilling of CFRP with a continuous-wave laser beam

    NASA Astrophysics Data System (ADS)

    Faas, S.; Freitag, C.; Boley, S.; Berger, P.; Weber, R.; Graf, T.

    2017-03-01

    The hot plume of ablation products generated during the laser drilling process of carbon fiber reinforced plastics (CFRP) with a continuous-wave laser beam was analyzed by means of high-speed imaging. The formation of compression shocks was observed within the flow of the evaporated material, which is an indication of flow speeds well above the local speed of sound. The flow speed of the hot ablation products can be estimated by analyzing the position of these compression shocks. We investigated the temporal evolution of the flow speed during the drilling process and the influence of the average laser power on the flow speed. The flow speed increases with increasing average laser powers. The moment of drilling through the material changes the conditions for the drilling process and was confirmed to influence the flow speed of the ablated material. Compression shocks can also be observed during laser cutting of CFRP with a moving laser beam.

  9. Growth of normally-immiscible materials (NIMs), binary alloys, and metallic fibers by hyperbaric laser chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Maxwell, J. L.; Black, M. R.; Chavez, C. A.; Maskaly, K. R.; Espinoza, M.; Boman, M.; Landstrom, L.

    2008-06-01

    This work demonstrates that two or more elements of negligible solubility (and no known phase diagram) can be co-deposited in fiber form by hyperbaric-pressure laser chemical vapor deposition (HP-LCVD). For the first time, Hg-W alloys were grown as fibers from mixtures of tungsten hexafluoride, mercury vapor, and hydrogen. This new class of materials is termed normally-immiscible materials (NIMs), and includes not only immiscible materials, but also those elemental combinations that have liquid states at exclusive temperatures. This work also demonstrates that a wide variety of other binary and ternary alloys, intermetallics, and mixtures can be grown as fibers, e.g. silicon-tungsten, aluminum-silicon, boron-carbon-silicon, and titanium-carbon-nitride. In addition, pure metallic fibers of aluminum, titanium, and tungsten were deposited, demonstrating that materials of high thermal conductivity can indeed be grown in three-dimensions, provided sufficient vapor pressures are employed. A wide variety of fiber properties and microstructures resulted depending on process conditions; for example, single crystals, fine-grained alloys, and glassy metals could be deposited.

  10. Optical caries diagnostics: comparison of laser spectroscopic PNC method with method of laser integral fluorescence

    NASA Astrophysics Data System (ADS)

    Masychev, Victor I.

    2000-11-01

    In this research we present the results of approbation of two methods of optical caries diagnostics: PNC-spectral diagnostics and caries detection by laser integral fluorescence. The research was conducted in a dental clinic. PNC-method analyses parameters of probing laser radiation and PNC-spectrums of stimulated secondary radiations: backscattering and endogenous fluorescence of caries-involved bacterias. He-Ne-laser ((lambda) =632,8 nm, 1-2mW) was used as a source of probing (stimulated) radiation. For registration of signals, received from intact and pathological teeth PDA-detector was applied. PNC-spectrums were processed by special algorithms, and were displayed on PC monitor. The method of laser integral fluorescence was used for comparison. In this case integral power of fluorescence of human teeth was measured. As a source of probing (stimulated) radiation diode lasers ((lambda) =655 nm, 0.1 mW and 630nm, 1mW) and He-Ne laser were applied. For registration of signals Si-photodetector was used. Integral power was shown in a digital indicator. Advantages and disadvantages of these methods are described in this research. It is disclosed that the method of laser integral power of fluorescence has the following characteristics: simplicity of construction and schema-technical decisions. However the method of PNC-spectral diagnostics are characterized by considerably more sensitivity in diagnostics of initial caries and capability to differentiate pathologies of various stages (for example, calculus/initial caries). Estimation of spectral characteristics of PNC-signals allows eliminating a number of drawbacks, which are character for detection by method of laser integral fluorescence (for instance, detection of fluorescent fillings, plagues, calculus, discolorations generally, amalgam, gold fillings as if it were caries.

  11. Direct analysis of intact biological macromolecules by low-energy, fiber-based femtosecond laser vaporization at 1042 nm wavelength with nanospray postionization mass spectrometry.

    PubMed

    Shi, Fengjian; Flanigan, Paul M; Archer, Jieutonne J; Levis, Robert J

    2015-03-17

    A fiber-based laser with a pulse duration of 435 fs and a wavelength of 1042 nm was used to vaporize biological macromolecules intact from the condensed phase into the gas phase for nanospray postionization and mass analysis. Laser vaporization of dried standard protein samples from a glass substrate by 10 Hz bursts of 20 pulses having 10 μs pulse separation and <50 μJ pulse energy resulted in signal comparable to a metal substrate. The protein signal observed from an aqueous droplet on a glass substrate was negligible compared to either a droplet on metal or a thin film on glass. The mass spectra generated from dried and aqueous protein samples by the low-energy, fiber laser were similar to the results from high-energy (500 μJ), 45-fs, 800-nm Ti:sapphire-based femtosecond laser electrospray mass spectrometry (LEMS) experiments, suggesting that the fiber-based femtosecond laser desorption mechanism involves a nonresonant, multiphoton process, rather than thermal- or photoacoustic-induced desorption. Direct analysis of whole blood performed without any pretreatment resulted in features corresponding to hemoglobin subunit-heme complex ions. The observation of intact molecular ions with low charge states from protein, and the tentatively assigned hemoglobin α subunit-heme complex from blood suggests that fiber-based femtosecond laser vaporization is a "soft" desorption source at a laser intensity of 2.39 × 10(12) W/cm(2). The low-energy, turnkey fiber laser demonstrates the potential of a more robust and affordable laser for femtosecond laser vaporization to deliver biological macromolecules into the gas phase for mass analysis.

  12. Nonlinear absorption, scattering, and extinction of laser radiation by two-layered spherical system-gold nanoparticle and vapor shell in water

    NASA Astrophysics Data System (ADS)

    Pustovalov, V. K.; Astafyeva, L. G.

    2011-12-01

    Nonlinear absorption, scattering and extinction of laser radiation with wavelengths 532, 633 nm by spherical gold nanoparticles (NPs) with radii in the range of 5-100 nm placed in water and heated by laser radiation with formation and expansion of vapor nanoshells is theoretically investigated. Decrease of absorption, decrease and subsequent increase of scattering and extinction with increasing of shell radius beginning from the initial period of shell expansion is established. Optical indicatrixes and nonlinear behavior of scattered radiation are investigated including the examination of these characteristics during the adiabatic expansion of vapor shell. Formation of vapor nanoshells (bubbles) as a result of the action of short laser pulses on NPs placed in tissue was proposed for cutting of tissue.

  13. Simultaneous detection of molecular oxygen and water vapor in the tissue optical window using tunable diode laser spectroscopy.

    PubMed

    Persson, Linda; Lewander, Märta; Andersson, Mats; Svanberg, Katarina; Svanberg, Sune

    2008-04-20

    We report on a dual-diode laser spectroscopic system for simultaneous detection of two gases. The technique is demonstrated by performing gas measurements on absorbing samples such as an air distance, and on absorbing and scattering porous samples such as human tissue. In the latter it is possible to derive the concentration of one gas by normalizing to a second gas of known concentration. This is possible if the scattering and absorption of the bulk material is equal or similar for the two wavelengths used, resulting in a common effective pathlength. Two pigtailed diode lasers are operated in a wavelength modulation scheme to detect molecular oxygen ~760 nm and water vapor ~935 nm within the tissue optical window (600 nm to 1.3 mum). Different modulation frequencies are used to distinguish between the two wavelengths. No crosstalk can be observed between the gas contents measured in the two gas channels. The system is made compact by using a computer board and performing software-based lock-in detection. The noise floor obtained corresponds to an absorption fraction of approximately 6x10(-5) for both oxygen and water vapor, yielding a minimum detection limit of ~2 mm for both gases in ambient air. The power of the technique is illustrated by the preliminary results of a clinical trial, nonintrusively investigating gas in human sinuses.

  14. Monitoring of temperature increase and tissue vaporization during laser interstitial thermotherapy of ex vivo swine liver by computed tomography.

    PubMed

    Schena, E; Saccomandi, P; Giurazza, F; Del Vescovo, R; Mortato, L; Martino, M; Panzera, F; Di Matteo, F M; Beomonte Zobel, B; Silvestri, S

    2013-01-01

    Laser interstitial thermotherapy (LITT) is a minimally invasive technique used to thermally destroy tumour cells. Being based on hyperthermia, LITT outcome depends on the temperature distribution inside the tissue. Recently, CT scan thermometry, based on the dependence of the CT number (HU) on tissue temperature (T) has been introduced during LITT; it is an attractive approach to monitor T because it overcomes the concerns related to the invasiveness. We performed LITT on nine ex vivo swine livers at three different laser powers, (P=1.5 W, P=3 W, P=5 W) with a constant treatment time t=200 s; HU is averaged on two ellipsoidal regions of interest (ROI) of 0.2 cm2, placed at two distances from the applicator (d=3.6 mm and d=8.7 mm); a reference ROI was placed away from the applicator (d=30 mm). The aim of this study is twofold: 1) to evaluate the effect of the T increase in terms of HU variation in ex vivo swine livers undergoing LITT; and 2) to estimate the P value for tissue vaporization. To the best of our knowledge, this is the first study focused on the HU variation in swine livers undergoing LITT at different P. The reported findings could be useful to assess the effect of LITT on the liver in terms of both T changes and tissue vaporization, with the aim to obtain an effective therapy.

  15. MoXy fiber with active cooling cap for bovine prostate vaporization with high power 200W 532 nm laser

    NASA Astrophysics Data System (ADS)

    Peng, Steven Y.; Kang, Hyun Wook; Pirzadeh, Homa; Stinson, Douglas

    2011-03-01

    A novel MoXyTM fiber delivery device with Active Cooling Cap (ACCTM) is designed to transmit up to 180W of 532 nm laser light to treat benign prostatic hyperplasia (BPH). Under such high power tissue ablation, effective cooling is key to maintaining fiber power transmission and ensuring the reliability of the fiber delivery device To handle high power and reduce fiber degradation, the MoXy fiber features a larger core size (750 micrometer) and an internal fluid channel to ensure better cooling of the fiber tip to prevent the cap from burning, detaching, or shattering during the BPH treatment. The internal cooling channel was created with a metal cap and tubing that surrounds the optical fiber. In this study MoXy fibers were used to investigate the effect of power levels of 120 and 200 W on in-vitro bovine prostate ablation using a 532 nm XPSTM laser system. For procedures requiring more than 100 kJ, the MoXy fiber at 200W removed tissue at twice the rate of the current HPS fiber at 120W. The fiber maintained a constant tissue vaporization rate during the entire tissue ablation process. The coagulation at 200W was about 20% thicker than at 120W. In conclusion, the new fibers at 200W doubled the tissue removal rate, maintained vaporization efficiency throughout delivery of 400kJ energy, and induced similar coagulation to the existing HPS fiber at 120W.

  16. Chemical vapor deposition of highly adherent diamond coatings onto co-cemented tungsten carbides irradiated by high power diode laser.

    PubMed

    Barletta, M; Rubino, G; Valle, R; Polini, R

    2012-02-01

    The present investigation deals with the definition of a new eco-friendly alternative to pretreat Co-cemented tungsten carbide (WC-Co) substrates before diamond deposition by hot filament chemical vapor deposition (HFCVD). In particular, WC-5.8 wt %Co substrates were submitted to a thermal treatment by a continuous wave-high power diode laser to reduce surface Co concentration and promote the reconstruction of the WC grains. Laser pretreatments were performed both in N(2) and Ar atmosphere to prevent substrate oxidation. Diamond coatings were deposited onto the laser pretreated substrates by HFCVD. For comparative purpose, diamond coatings were also deposited on WC-5.8 wt %Co substrates chemically etched by the well-known two-step pretreatment employing Murakami's reagent and Caro's acid. Surface morphology, microstructure, and chemical composition of the WC-5.8 wt %Co substrates after the different pretreatments and the deposition of diamond coatings were assessed by surface profiler, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction analyses. Wear performance of the diamond coatings was checked by dry sliding linear reciprocating tribological tests. The worn volume of the diamond coatings deposited on the laser pretreated substrates was always found lower than the one measured on the chemically etched substrates, with the N(2) atmosphere being particularly promising.

  17. Initial alignment method for free space optics laser beam

    NASA Astrophysics Data System (ADS)

    Shimada, Yuta; Tashiro, Yuki; Izumi, Kiyotaka; Yoshida, Koichi; Tsujimura, Takeshi

    2016-08-01

    The authors have newly proposed and constructed an active free space optics transmission system. It is equipped with a motor driven laser emitting mechanism and positioning photodiodes, and it transmits a collimated thin laser beam and accurately steers the laser beam direction. It is necessary to introduce the laser beam within sensible range of the receiver in advance of laser beam tracking control. This paper studies an estimation method of laser reaching point for initial laser beam alignment. Distributed photodiodes detect laser luminescence at respective position, and the optical axis of laser beam is analytically presumed based on the Gaussian beam optics. Computer simulation evaluates the accuracy of the proposed estimation methods, and results disclose that the methods help us to guide the laser beam to a distant receiver.

  18. A Review on Prediction Methods for Molar Enthalpies of Vaporization of Hydrocarbons: The ELBA Method as the Best Answer

    NASA Astrophysics Data System (ADS)

    Santos, Rui C.; Leal, João P.

    2012-12-01

    A review on prediction methods for molar enthalpies of vaporization at T = 298.15 K of hydrocarbons is presented. A new method is proposed and compared with six of the most common used ones from the literature. This new method, the extended Laidler bond additivity (ELBA), was applied to the prediction of standard molar enthalpies of vaporization of hydrocarbons (alkanes, alkenes, alkynes, polyenes, poly-ynes, cycloalkanes, cycloalkenes, benzene compounds, biphenyl compounds, and polyphenyl compounds) at T = 298.15 K. A total of 260 experimental standard molar enthalpies of vaporization at T = 298.15 K were used for the parameters optimization. Comparison between the experimental values and those calculated using ELBA led to an average absolute difference of 0.35 kJ mol-1, corresponding to an average relative error of 0.92%. In addition, this new method proves to be better than the ones used for comparison with an independent set of 83 experimental standard molar enthalpies of vaporization at T = 298.15 K.

  19. On the Applicability of Linearization Method of Vapor Flow in Porous Media

    NASA Astrophysics Data System (ADS)

    Li, J.; Zhan, H.; Huang, G.

    2009-12-01

    For decades, linearization treatment has been commonly applied in vapor flow problems in natural gas engineering, soil vapor extraction (SVE) design, barometric and pneumatic pumping in order to make the governing equation of vapor flow tractable for analytical solutions. In this study, we will particularly investigate two linearization methods: one is the standard linearization method using the squared pressure as the dependent variable (method A), and the other is using the history-dependent averaged pressure to calculate the diffusivity of flow as proposed by Wu et al. (1998) (method B). Although attempts were tried to enhance the confidence for applications of the linearization methods, errors caused by such approximations have not been analyzed to great details. In this work, we validate the linearization methods A and B based on a numerical solution, which is obtained using stiff integrator ODE15s to deal with the temporal derivative and finite-difference to deal with the spatial derivative. This numerical solution is obtained with sufficiently fine temporal and spatial resolutions to make the numerical errors negligible, thus is regarded as the “exact solution”. Two scenarios, the one-dimensional vapor flow under constant pressure difference and radial vapor flow under constant extraction rate, are investigated respectively. A new linearization method is proposed to reduce the error of pressure estimation in methods A and B. This study shows a few features of the linearization methods A and B. First, both methods A and B provide adequate pressure evaluation at early times under relatively small constant pressure difference or gas injection rate, otherwise large discrepancy from the exact solution becomes significant. Second, the maximum value of error of the method A is relatively insensitive to time for either scenarios investigated. Third, the pressure evaluation of the method B shows a transition from underestimate to overestimate (or from

  20. A field-space conformal-solution method: Binary vapor-liquid phase behavior

    NASA Astrophysics Data System (ADS)

    Storvick, T. S.; Fox, J. R.

    1990-01-01

    The field-space conformal solution method provides an entirely new thermodynamic framework for the description of fluid mixtures in terms of the properties of a pure reference fluid. The utility and performance of the method are examined in the special case of vapor-liquid equilibrium correlation for simple mixtures. This is one of several cases in which field-space methods have numerical or theoretical advantages over methods presently used in mixture property correlation; only properties along the vapor pressure curve of the purefluid reference system are required for a complete description of the mixture phase behavior. Vapor-liquid equilibrium data for three binary hydrocarbon mixtures, n-butane + n-pentane, n-butane + n-hexane, and n-butane + n-octane, are correlated with a simple implementation of the method having two independent mixture parameters. Two pure-fluid equations of state, a Peng-Robinson equation and a 32-constant modified Benedict-Webb-Rubin equation, are tested as reference systems. The effects of differences in the quality of the reference system and of a range of mixture component size ratios are examined.

  1. Highly Controlled Codeposition Rate of Organolead Halide Perovskite by Laser Evaporation Method.

    PubMed

    Miyadera, Tetsuhiko; Sugita, Takeshi; Tampo, Hitoshi; Matsubara, Koji; Chikamatsu, Masayuki

    2016-10-05

    Organolead-halide perovskites can be promising materials for next-generation solar cells because of its high power conversion efficiency. The method of precise fabrication is required because both solution-process and vacuum-process fabrication of the perovskite have problems of controllability and reproducibility. Vacuum deposition process was expected to achieve precise control; however, vaporization of amine compound significantly degrades the controllability of deposition rate. Here we achieved the reduction of the vaporization by implementing the laser evaporation system for the codeposition of perovskite. Locally irradiated continuous-wave lasers on the source materials realized the reduced vaporization of CH3NH3I. The deposition rate was stabilized for several hours by adjusting the duty ratio of modulated laser based on proportional-integral control. Organic-photovoltaic-type perovskite solar cells were fabricated by codeposition of PbI2 and CH3NH3I. A power-conversion efficiency of 16.0% with reduced hysteresis was achieved.

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

    DOEpatents

    Ownby, G.W.; White, C.W.; Zehner, D.M.

    1979-12-28

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

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

    DOEpatents

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

    1981-01-01

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

  4. Thermodynamic properties and vapor pressures of polar fluids from a four-parameter corresponding-states method

    SciTech Connect

    Wilding, W.V.; Johnson, J.K.; Rowley, R.L.

    1987-11-01

    A recently proposed extended Lee-Kesler corresponding-states method (ELK) for polar fluids which accurately predicts compressibility factors and departure functions is considered. Tables of polar deviation functions have been generated and values of the shape/size and polar parameters for 52 polar fluids have been calculated, allowing the method to be used for quick hand calculation in addition to the previous, more accurate, computer applications. Additionally, vapor pressures of 44 pure polar fluids were computed using the full version of the ELK and the equality of the Gibbs free energy criterion for phase equilibrium. An ELK vapor pressure correlation is proposed which is essentially numerically equivalent to, but computationally simpler than, the former method. Computed vapor pressures agree with experimental values as well or better than other vapor pressure equations designed exclusively for vapor pressure prediction of polar fluids.

  5. Ambient Molecular Analysis of Biological Tissue Using Low-Energy, Femtosecond Laser Vaporization and Nanospray Postionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Shi, Fengjian; Flanigan, Paul M.; Archer, Jieutonne J.; Levis, Robert J.

    2016-03-01

    Direct analysis of plant and animal tissue samples by laser electrospray mass spectrometry (LEMS) was investigated using low-energy, femtosecond duration laser vaporization at wavelengths of 800 and 1042 nm followed by nanospray postionization. Low-energy (<50 μJ), fiber-based 1042 nm LEMS (F-LEMS) allowed interrogation of the molecular species in fresh flower petal and leaf samples using 435 fs, 10 Hz bursts of 20 pulses from a Ytterbium-doped fiber laser and revealed comparable results to high energy (75-1120 μJ), 45 fs, 800 nm Ti:Sapphire-based LEMS (Ti:Sapphire-LEMS) measurements. Anthocyanins, sugars, and other metabolites were successfully detected and revealed the anticipated metabolite profile for the petal and leaf samples. Phospholipids, especially phosphatidylcholine, were identified from a fresh mouse brain section sample using Ti:Sapphire-LEMS without the application of matrix. These lipid features were suppressed in both the fiber-based and Ti:Sapphire-based LEMS measurements when the brain sample was prepared using the optimal cutting temperature compounds that are commonly used in animal tissue cryosections.

  6. Total internal reflection laser tools and methods

    DOEpatents

    Zediker, Mark S.; Faircloth, Brian O.; Kolachalam, Sharath K.; Grubb, Daryl L.

    2016-02-02

    There is provided high power laser tools and laser heads that utilize total internal reflection ("TIR") structures to direct the laser beam along a laser beam path within the TIR structure. The TIR structures may be a TIR prism having its hypotenuse as a TIR surface.

  7. Ultrafast laser based coherent control methods for explosives detection

    SciTech Connect

    Moore, David Steven

    2010-12-06

    The detection of explosives is a notoriously difficult problem, especially at stand-off, due to their (generally) low vapor pressure, environmental and matrix interferences, and packaging. We are exploring Optimal Dynamic Detection of Explosives (ODD-Ex), which exploits the best capabilities of recent advances in laser technology and recent discoveries in optimal shaping of laser pulses for control of molecular processes to significantly enhance the standoff detection of explosives. The core of the ODD-Ex technique is the introduction of optimally shaped laser pulses to simultaneously enhance sensitivity to explosives signatures while dramatically improving specificity, particularly against matrix materials and background interferences. These goals are being addressed by operating in an optimal non-linear fashion, typically with a single shaped laser pulse inherently containing within it coherently locked control and probe subpulses. Recent results will be presented.

  8. Method for changing the cross section of a laser beam

    DOEpatents

    Sweatt, William C.; Seppala, Lynn

    1995-01-01

    A technique is disclosed herein in which a circular optical beam, for example a copper vapor laser (CVL) beam, is converted to a beam having a profile other than circular, e.g. square or triangular. This is accomplished by utilizing a single optical mirror having a reflecting surface designed in accordance with a specifically derived formula in order to make the necessary transformation, without any substantial light loss and without changing substantially the intensity profile of the circular beam which has a substantially uniform intensity profile. In this way, the output beam can be readily directed into the dye cell of a dye laser.

  9. Method for changing the cross section of a laser beam

    DOEpatents

    Sweatt, W.C.; Seppala, L.

    1995-12-05

    A technique is disclosed herein in which a circular optical beam, for example a copper vapor laser (CVL) beam, is converted to a beam having a profile other than circular, e.g. square or triangular. This is accomplished by utilizing a single optical mirror having a reflecting surface designed in accordance with a specifically derived formula in order to make the necessary transformation, without any substantial light loss and without changing substantially the intensity profile of the circular beam which has a substantially uniform intensity profile. In this way, the output beam can be readily directed into the dye cell of a dye laser. 4 figs.

  10. Method for mounting laser fusion targets for irradiation

    DOEpatents

    Fries, R. Jay; Farnum, Eugene H.; McCall, Gene H.

    1977-07-26

    Methods for preparing laser fusion targets of the ball-and-disk type are disclosed. Such targets are suitable for irradiation with one or two laser beams to produce the requisite uniform compression of the fuel material.

  11. Growth of ZnTe by Physical Vapor Transport and Traveling Heater Method

    NASA Technical Reports Server (NTRS)

    Su, Ching-Hua; Volz, M. P.; Gillies, D. C.; Szofran, F. R.; Lehoczky, S. L.; Dudley, M.; Yao, G.-D.; Zhou, Wenyi

    1993-01-01

    ZnTe crystals were grown by horizontal physical vapor transport (PVT) and a Te-solution vertical traveling heater method (THM). The grown crystals were examined by X-ray Laue diffraction technique and Hall measurements to determine the growth orientation and the electrical properties of the crystals. They were also characterized by low temperature infrared (IR) absorption measurements. Several sets of distinct peaks were observed in the IR absorption spectra for the THM samples and were identified as resulting from CU(2+) impurities. Similar measurements on vapor grown ZnTe showed featureless absorption spectra. Chemical analyses were carried out to measure the impurity content in various ZnTe samples and synchrotron radiation topography was used to Study crystalline microstructure of the (111) ZnTe single crystals grown by PVT.

  12. Deposition of zinc films by laser method

    SciTech Connect

    Goncharov, V K; Gusakov, G A; Puzyrev, M V

    2015-04-30

    Conditions of laser irradiation of a zinc target under which large droplets of a laser target material are not formed in the erosion plume are found, and zinc nanofilms with a minimum number of large particles on the surface are produced. The surface structure, thickness and optical characteristics of zinc films are determined as functions of the power density of laser radiation falling on a zinc target. The evaporation threshold for a zinc target irradiated by nanosecond laser pulses is found. (laser technologies)

  13. Efficacy of a vaporization-resection of the prostate median lobe enlargement and vaporization of the prostate lateral lobe for benign prostatic hyperplasia using a 120-W GreenLight high-performance system laser: the effect on storage symptoms.

    PubMed

    Kim, Kang Sup; Choi, Sae Woong; Bae, Woong Jin; Kim, Su Jin; Cho, Hyuk Jin; Hong, Sung-Hoo; Lee, Ji Youl; Hwang, Tae-Kon; Kim, Sae Woong

    2015-05-01

    GreenLight laser photoselective vaporization of the prostate (PVP) was established as a minimally invasive procedure to treat patients with benign prostatic hyperplasia (BPH). However, it may be difficult to achieve adequate tissue removal from a large prostate, particularly those with an enlarged median lobe. The purpose of this study was to investigate the feasibility and clinical effect of a 120-W GreenLight high-performance system laser vaporization-resection for an enlarged prostate median lobe compared with those of only vaporization. A total of 126 patients from January 2010 to January 2014 had an enlarged prostate median lobe and were included in this study. Ninety-six patients underwent vaporization only (VP group), and 30 patients underwent vaporization-resection for an enlarged median lobe (VR group). The clinical outcomes were International Prostate Symptoms Score (IPSS), quality of life (QOL), maximum flow rate (Q max), and post-void residual urine volume (PVR) assessed at 1, 3, 6, and 12 months postoperatively between the two groups. The parameters were not significantly different preoperatively between the two groups, except for PVR. Operative time and laser time were shorter in the VR group than those in the VP group. (74.1 vs. 61.9 min and 46.7 vs. 37.8 min; P = 0.020 and 0.013, respectively) and used less energy (218.2 vs. 171.8 kJ, P = 0.025). Improved IPSS values, increased Q max, and a reduced PVR were seen in the two groups. In particular, improved storage IPSS values were higher at 1 and 3 months in the VR group than those in the VP group (P = 0.030 and 0.022, respectively). No significant complications were detected in either group. Median lobe tissue vaporization-resection was complete, and good voiding results were achieved. Although changes in urinary symptoms were similar between patients who received the two techniques, shorter operating time and lower energy were superior with the vaporization-resection technique. In

  14. Group vector space method for estimating enthalpy of vaporization of organic compounds at the normal boiling point.

    PubMed

    Wenying, Wei; Jinyu, Han; Wen, Xu

    2004-01-01

    The specific position of a group in the molecule has been considered, and a group vector space method for estimating enthalpy of vaporization at the normal boiling point of organic compounds has been developed. Expression for enthalpy of vaporization Delta(vap)H(T(b)) has been established and numerical values of relative group parameters obtained. The average percent deviation of estimation of Delta(vap)H(T(b)) is 1.16, which show that the present method demonstrates significant improvement in applicability to predict the enthalpy of vaporization at the normal boiling point, compared the conventional group methods.

  15. Photodynamic Therapy Combined with CO2 Laser Vaporization on Disseminated Superficial Actinic Porokeratosis: A Report of 2 Cases on the Face

    PubMed Central

    Kim, Hei Sung; Baek, Ji Hye; Park, Young Min; Kim, Hyung Ok

    2011-01-01

    Disseminated superficial actinic porokeratosis (DSAP) is a skin condition that usually shows a poor response to different modalities of treatment. Herein we describe 2 patients with DSAP on the face, each treated with 3 to 4 sessions of photodynamic therapy combined with laser vaporization. PMID:22148053

  16. Vaporization front in the interaction of a high-energy laser with aerosols - A solitary wave

    NASA Astrophysics Data System (ADS)

    Lee, C. T.; Miller, T. G.

    1982-06-01

    If a high-energy laser beam were to propagate through highly absorbent aerosols, the aerosols might be subject to extinction by evaporation. This could occur, for instance, if a high-energy CO2 laser beam were to propagate through a medium containing a mist of water droplets. The incident energy would evaporate the droplets, thus increasing the transmission with time. In this paper, solitary waves are obtained as the asymptotic solution to the coupled nonlinear equations describing such an interaction.

  17. Self-generating magnetometer with laser pumping employment in “end resonance” wall coated vapor cell atomic clocks

    NASA Astrophysics Data System (ADS)

    Baranov, A. A.; Ermak, S. V.; Smolin, R. V.; Semenov, V. V.

    2016-06-01

    This paper presents the results of two double resonance signals correlation investigation. These signals were observed synchronously in optically oriented Rb87 vapors with laser pumping in a dual scheme: low frequency Mx-magnetometer and microwave frequency discriminator. Analytical studies of the scalar and vector light shift components contribution to the frequency instability of the end resonance microwave transitions are presented. An experimental demonstration of the light shift components mutual compensation in optically pumped Rb87 atoms was provided. The results were processed in terms of Allan variance, which demonstrated an effect of decreasing frequency variation at averaging times more than 100 s for a joint scheme of the end resonance microwave transition and selfgenerating (Mx) magnetometer.

  18. Real-time vapor detection of nitroaromatic explosives by catalytic thermal dissociation blue diode laser cavity ring-down spectroscopy

    NASA Astrophysics Data System (ADS)

    Taha, Youssef M.; Odame-Ankrah, Charles A.; Osthoff, Hans D.

    2013-09-01

    A compact blue diode laser catalytic thermal dissociation cavity ring-down spectrometer (cTD-CRDS) to detect vapors of nitroaromatic explosives is described. The instrument uses heated platinum(IV) oxide catalyst to convert nitroaromatic compounds to NO2, which is detected at 405 nm. Using the relatively volatile nitrobenzene as a test compound, we show by Fourier Transform Infrared Spectroscopy (FTIR) in off-line experiments that nitroaromatics can be quantitatively converted to NO2. The cTD-CRDS detection limit was 0.3 parts-per-billion by volume (ppbv) and sufficiently low to allow the detection of a room temperature sample of 2,4,6-trinitrotoluene (TNT) without sample preconcentration.

  19. Operational efficiency increase in a copper vapor laser due to the replacement of vacuum jacket brewster windows with flat windows

    NASA Technical Reports Server (NTRS)

    Estep, Lee; Witherspoon, Ned; Holloway, John; Price, Brian; Miller, Robert

    1989-01-01

    The vacuum integrity of the discharge tube of a copper vapor laser (CVL) is normally protected by Brewster angled windows. In an attempt to increase the operating efficiency of the CVL, flat windows were used to replace the Brewster windows. Experimental data confirm that the overall efficiency of the CVL does increase when such windows are used. The experimental results are discussed in terms of a computer model found in the literature. The cause of the efficiency increase appears due to a double optical cavity set up by the flat windows. However, the variation of the efficiency due to changes in the pulse repetition frequency (PRF) and buffer gas pressure are less well understood.

  20. Method of making AlInSb by metal-organic chemical vapor deposition

    DOEpatents

    Biefeld, Robert M.; Allerman, Andrew A.; Baucom, Kevin C.

    2000-01-01

    A method for producing aluminum-indium-antimony materials by metal-organic chemical vapor deposition (MOCVD). This invention provides a method of producing Al.sub.X In.sub.1-x Sb crystalline materials by MOCVD wherein an Al source material, an In source material and an Sb source material are supplied as a gas to a heated substrate in a chamber, said Al source material, In source material, and Sb source material decomposing at least partially below 525.degree. C. to produce Al.sub.x In.sub.1-x Sb crystalline materials wherein x is greater than 0.002 and less than one.

  1. Chemical vapor deposition techniques and related methods for manufacturing microminiature thermionic converters

    DOEpatents

    King, Donald B.; Sadwick, Laurence P.; Wernsman, Bernard R.

    2002-06-25

    Methods of manufacturing microminiature thermionic converters (MTCs) having high energy-conversion efficiencies and variable operating temperatures using MEMS manufacturing techniques including chemical vapor deposition. The MTCs made using the methods of the invention incorporate cathode to anode spacing of about 1 micron or less and use cathode and anode materials having work functions ranging from about 1 eV to about 3 eV. The MTCs also exhibit maximum efficiencies of just under 30%, and thousands of the devices can be fabricated at modest costs.

  2. Quantitative Imaging of Ozone Vapor Using Photofragmentation Laser-Induced Fluorescence (LIF).

    PubMed

    Larsson, Kajsa; Hot, Dina; Ehn, Andreas; Lantz, Andreas; Weng, Wubin; Aldén, Marcus; Bood, Joakim

    2017-01-01

    In the present work, the spectral properties of gaseous ozone (O3) have been investigated aiming to perform quantitative concentration imaging of ozone by using a single laser pulse at 248 nm from a KrF excimer laser. The O3 molecule is first photodissociated by the laser pulse into two fragments, O and O2. Then the same laser pulse electronically excites the O2 fragment, which is vibrationally hot, whereupon fluorescence is emitted. The fluorescence intensity is found to be proportional to the concentration of ozone. Both emission and absorption characteristics have been investigated, as well as how the laser fluence affects the fluorescence signal. Quantitative ozone imaging data have been achieved based on calibration measurements in known mixtures of O3. In addition, a simultaneous study of the emission intensity captured by an intensified charge-coupled device (ICCD) camera and a spectrograph has been performed. The results show that any signal contribution not stemming from ozone is negligible compared to the strong fluorescence induced by the O2 fragment, thus proving interference-free ozone imaging. The single-shot detection limit has been estimated to ∼400 ppm. The authors believe that the presented technique offers a valuable tool applicable in various research fields, such as plasma sterilization, water and soil remediation, and plasma-assisted combustion.

  3. Polarization methods for diode laser excitation of solid state lasers

    DOEpatents

    Holtom, Gary R.

    2008-11-25

    A mode-locked laser employs a coupled-polarization scheme for efficient longitudinal pumping by reshaped laser diode bars. One or more dielectric polarizers are configured to reflect a pumping wavelength having a first polarization and to reflect a lasing wavelength having a second polarization. A Yb-doped gain medium can be used that absorbs light having a first polarization and emits light having a second polarization. Using such pumping with laser cavity dispersion control, pulse durations of less than 100 fs can be achieved.

  4. Studies on Aspirin Crystals Generated by a Modified Vapor Diffusion Method.

    PubMed

    Mittal, Amit; Malhotra, Deepak; Jain, Preeti; Kalia, Anupama; Shunmugaperumal, Tamilvanan

    2016-08-01

    The objectives of the current investigation were (1) to study the influence of selected two different non-solvents (diethylether and dichloromethane) on the drug crystal formation of a model drug, aspirin (ASP-I) by the modified vapor diffusion method and (2) to characterize and compare the generated crystals (ASP-II and ASP-III) using different analytical techniques with that of unprocessed ASP-I. When compared to the classical vapor diffusion method which consumes about 15 days to generate drug crystals, the modified method needs only 12 h to get the same. Fourier transform-infrared spectroscopy (FT-IR) reveals that the internal structures of ASP-II and ASP-III crystals were identical when compared with ASP-I. Although the drug crystals showed a close similarity in X-ray diffraction patterns, the difference in the relative intensities of some of the diffraction peaks (especially at 2θ values of around 7.7 and 15.5) could be attributed to the crystal habit or crystal size modification. Similarly, the differential scanning calorimetry (DSC) study speculates that only the crystal habit modifications might occur but without involving any change in internal structure of the generated drug polymorphic form I. This is further substantiated from the scanning electron microscopy (SEM) pictures that indicated the formation of platy shape for the ASP-II crystals and needle shape for the ASP-III crystals. In addition, the observed slow dissolution of ASP crystals should indicate polymorph form I formation. Thus, the modified vapor diffusion method could routinely be used to screen and legally secure all possible forms of other drug entities too.

  5. Development of Solid State Laser Materials for Application in Lasers for Atmospheric Ozone and Water Vapor Sensing

    NASA Technical Reports Server (NTRS)

    Noginov, Makhail A.; Loutts, G. B.

    2002-01-01

    We have grown neodymium doped mixed apatite crystals, (Sr(x)Ba(l-x)5(PO4)3F, Sr5(P(1-x)V(x)O4)3F, and Ba5(P(1-x)V(x)O4)3F, and spectroscopically studied them as potential gain media for a laser source for atmospheric water sensing operating at 944.11 nm0. We conclude that an appropriate apatite host material for a 944.11 nm laser should be a mixture of Sr5(PO4)3F with a small fraction of Ba5(PO4)3F. The precise wavelength tuning around 944.11 nm can be accomplished by varying the host composition, temperature, and threshold population inversion. In apatite crystals of mixed composition, the Amplified Spontaneous Emission (ASE) loss at 1.06 microns is predicted to be significantly smaller than that in the end members.

  6. Highly uniform and reproducible vertical-cavity surface emitting lasers grown by metalorganic chemical vapor deposition

    SciTech Connect

    Hou, H.Q.; Chui, H.C.; Choquette, K.D.; Hammons, B.E.; Breiland, W.G.; Geib, K.M.

    1996-01-01

    We show that the uniformity of the lasing wavelength of vertical-cavity surface emitting lasers (VCSELs) can be as good as {plus_minus}0.3% across a entire 3 in. wafer in MOCVD growth with a similar run-to-run reproducibility.

  7. Optimization methods of the net emission computation applied to cylindrical sodium vapor plasma

    SciTech Connect

    Hadj Salah, S. Hajji, S.; Ben Hamida, M. B.; Charrada, K.

    2015-01-15

    An optimization method based on a physical analysis of the temperature profile and different terms in the radiative transfer equation is developed to reduce the time computation of the net emission. This method has been applied for the cylindrical discharge in sodium vapor. Numerical results show a relative error of spectral flux density values lower than 5% with an exact solution, whereas the computation time is about 10 orders of magnitude less. This method is followed by a spectral method based on the rearrangement of the lines profile. Results are shown for Lorentzian profile and they demonstrated a relative error lower than 10% with the reference method and gain in computation time about 20 orders of magnitude.

  8. Laser methods for the control of atmospheric gases and gases which pollute the atmosphere

    NASA Astrophysics Data System (ADS)

    Antipov, A. B.; Zuev, V. E.; Kapitanov, V. A.; Lopasov, V. P.; Lukianenko, S. F.; Sinitsa, L. N.; Sapozhnikova, V. A.

    Laser methods for the control of atmospheric pollutants are currently being developed. Laser devices for gas analysis are being designed, taking into account the analytical determination of carbon monoxide, ozone, nitric oxide, and acetylene. The operation of these devices is based on the absorption of radiation, and the wavelength region from 5 to 10 microns is utilized. However, an employment of this spectral region introduces problems in connection with the location of the intense vibrational-rotational absorption spectrum of water vapor and CO2 in this wavelength region. The present investigation is, therefore, concerned with the use of the wavelength region from 0.5 to 3.5 microns as a basis for the design of suitable laser devices for analytical applications. An optoacoustic method is considered along with an 'intracavity absorption' method discussed by Belikova et al. (1972). A description is presented of the results obtained in measurements conducted with laser spectrometers. Performance data concerning a number of developed laser spectrometers are also provided.

  9. A numerical method based on transfer function for removing the noise of water vapor from terahertz spectra

    NASA Astrophysics Data System (ADS)

    Huang, Yu; Zhang, Zheng; Jin, Chen; Xie, Yijun; Wang, Wenai; Sun, Ping

    2016-10-01

    The water vapor noise will affect the accuracy of the extracted optical parameters based on terahertz time domain spectroscopy technology. Because vapor noise has the characteristics of wide distribution and high intensity, the existing denoising methods cannot be effectively applied to the THz signal with vapor noise. In this paper, a numerical denoising method is presented. First, based on Van Vleck-Weisskopf lineshape function and the linear absorption spectrum of water molecules in the HITRAN database, we have simulated the water vapor absorption spectrum with line width, and the continuum effect of water vapor molecules are considered in the simulation. Then, the transfer function of different humidity is constructed by the calculation of the water vapor absorption coefficient and the real refractive index; Finally, based on the propagation factor formula of the mutual effects of THz wave and water vapor, the THz signal of the Lacidipine sample containing vapor noise in the continuous frequency domain of 0.3-1.8THz is denoised by using the constructed transfer function of the water vapor; the optical parameters of the sample signal before and after denoising can be extracted. It can be seen that the optical parameters extracted from the denoised signal are close to the optical parameters in the nitrogen environment, which proves the effectiveness of denoising. Under low humidity, this method can still accurately extract the optical parameters of samples without nitrogen filling, which saves the cost, enhances the convenience of the application of terahertz time domain spectroscopy in pharmaceutical production, safety inspection, imaging etc.

  10. Method for laser drilling subterranean earth formations

    DOEpatents

    Shuck, Lowell Z.

    1976-08-31

    Laser drilling of subterranean earth formations is efficiently accomplished by directing a collimated laser beam into a bore hole in registry with the earth formation and transversely directing the laser beam into the earth formation with a suitable reflector. In accordance with the present invention, the bore hole is highly pressurized with a gas so that as the laser beam penetrates the earth formation the high pressure gas forces the fluids resulting from the drilling operation into fissures and pores surrounding the laser-drilled bore so as to inhibit deleterious occlusion of the laser beam. Also, the laser beam may be dynamically programmed with some time dependent wave form, e.g., pulsed, to thermally shock the earth formation for forming or enlarging fluid-receiving fissures in the bore.

  11. Method of forming ultra thin film devices by vacuum arc vapor deposition

    NASA Technical Reports Server (NTRS)

    Schramm, Harry F. (Inventor)

    2005-01-01

    A method for providing an ultra thin electrical circuit integral with a portion of a surface of an object, including using a focal Vacuum Arc Vapor Deposition device having a chamber, a nozzle and a nozzle seal, depressing the nozzle seal against the portion of the object surface to create an airtight compartment in the chamber and depositing one or more ultra thin film layer(s) only on the portion of the surface of the object, the layers being of distinct patterns such that they form the circuit.

  12. Synthesis and Characterization of Tin(IV) Oxide Obtained by Chemical Vapor Deposition Method.

    PubMed

    Nagirnyak, Svitlana V; Lutz, Victoriya A; Dontsova, Tatiana A; Astrelin, Igor M

    2016-12-01

    The effect of precursors on the characteristics of tin oxide obtained by chemical vapor deposition (CVD) method was investigated. The synthesis of nanosized tin(IV) oxide was carried out with the use of two different precursors: tin(II) oxalate obtained using tin chloride(II) and oxalic acid; tin(II) oxalate obtained using tin chloride(II); and ammonium oxalate. The synthesized tin(IV) oxide samples were studied by electron microscopy, X-ray diffraction and optical spectra. The lattice parameters of tin(IV) oxide samples were defined, the bandgap of samples were calculated.

  13. Synthesis and Characterization of Tin(IV) Oxide Obtained by Chemical Vapor Deposition Method

    NASA Astrophysics Data System (ADS)

    Nagirnyak, Svitlana V.; Lutz, Victoriya A.; Dontsova, Tatiana A.; Astrelin, Igor M.

    2016-07-01

    The effect of precursors on the characteristics of tin oxide obtained by chemical vapor deposition (CVD) method was investigated. The synthesis of nanosized tin(IV) oxide was carried out with the use of two different precursors: tin(II) oxalate obtained using tin chloride(II) and oxalic acid; tin(II) oxalate obtained using tin chloride(II); and ammonium oxalate. The synthesized tin(IV) oxide samples were studied by electron microscopy, X-ray diffraction and optical spectra. The lattice parameters of tin(IV) oxide samples were defined, the bandgap of samples were calculated.

  14. High-power (80-w) KTP laser vaporization of the prostate in the management of urinary retention: long-term follow up

    NASA Astrophysics Data System (ADS)

    Kleeman, M.; Nseyo, Unyime O.

    2004-07-01

    Introduction and Objectives: We have previously reported the use of high-powered photoselective vaporization of the prostate (PVP) for patients in urinary retention due to benign prostatic hyperplasia (BPH). PVP is a relatively new treatment for bladder outlet obstruction due to BPH, using laser energy to vaporize obstructing prostatic tissue. This study investigates the long-term follow up of patients treated with PVP for urinary retention. Materials and Methods: All participants signed informed consent, and were treated with high power 80 W quasi-continuous wave potassium-titanyl-phosphate (KTP) laser. Ten patients underwent the procedure from December 2001 until the present. One patient was excluded from the study for failure to return for follow-up. Mean patient follow-up was nine months, maximum of twelve months. Results: The mean pre-operative gland size by trans-rectal ultrasound was 48 grams. Mean urethral length was 3.2 cm. Mean laser time was 48.2 minutes and the mean energy usage was 82.2 kJoules. There were no peri-operative complications such as sepsis or measurable postoperative bleeding. The preoperative AUA Symptom Score (AUASS) decreased from a mean of 22.6 preoperatively to 17 at nine months postoperatively (p = 0.032). The Quality of Life Score (QOL) decreased from 4.6 preoperatively to 3.25 at 12 months postoperatively (p = 0.26). The maximum urine flow rate increased from a mean of 7.7 cc/sec preoperatively to 14.5 cc/sec at six months follow-up (p = 0.03). Conclusions: This follow-up study suggests that HP-KTP has a durable response in patients treated specifically for retention. It significantly improved urine flow rate and symptom score, and had a trend towards improvement in subjective quality of life. HP-KTP prostatectomy should be considered in treating patients in retention, especially those with significant co-morbidities or taking anticoagulation.

  15. Relativistic mirrors in laser plasmas (analytical methods)

    NASA Astrophysics Data System (ADS)

    Bulanov, S. V.; Esirkepov, T. Zh; Kando, M.; Koga, J.

    2016-10-01

    Relativistic flying mirrors in plasmas are realized as thin dense electron (or electron-ion) layers accelerated by high-intensity electromagnetic waves to velocities close to the speed of light in vacuum. The reflection of an electromagnetic wave from the relativistic mirror results in its energy and frequency changing. In a counter-propagation configuration, the frequency of the reflected wave is multiplied by the factor proportional to the Lorentz factor squared. This scientific area promises the development of sources of ultrashort x-ray pulses in the attosecond range. The expected intensity will reach the level at which the effects predicted by nonlinear quantum electrodynamics start to play a key role. We present an overview of theoretical methods used to describe relativistic flying, accelerating, oscillating mirrors emerging in intense laser-plasma interactions.

  16. The Vapor Pressure of Environmentally Significant Organic Chemicals: A Review of Methods and Data at Ambient Temperature

    SciTech Connect

    Delle Site, A.

    1997-01-01

    The experimental techniques and the prediction procedures for the determination or evaluation of the vapor pressure of environmentally relevant organic compounds are described; with 259 references examined. For each of them the characteristics of precision and accuracy are given, when available from the literature. The experimental methods are classified as {open_quotes}direct{close_quotes} and {open_quotes}indirect.{close_quotes} The first class includes all those which can measure directly the vapor pressure, while the second concerns those which need {open_quotes}known{close_quotes} vapor pressures of reference compounds for the calibration. Prediction methods are based on the application of the Clapeyron{endash}Clausius equation or on the quantitative structure-property relationships. Also correlation methods require a suitable calibration. The vapor pressures at ambient temperature for several polycyclic aromatic hydrocarbons, polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and furans, selected pesticides, and some reference compounds are tabulated together with the vapor pressure equations and the enthalpy values in the temperature range of measurement. A critical comparison, based on a statistical analysis of the data obtained with different methods and derived from 152 references, is also carried out. {copyright} {ital 1996 American Institute of Physics and American Chemical Society.}{ital Key words:} chlorinated biphenyls; chlorinated dioxins; critically reviewed data; critically reviewed methods; pesticides; polynuclear aromatics; vapor pressure. {copyright} {ital 1996} {ital American Institute of Physics and American Chemical Society}

  17. Progress Toward an Autonomous Field Deployable Diode Laser Based Differential Absorption Lidar (DIAL) for Profiling Water Vapor in the Lower Troposphere

    NASA Astrophysics Data System (ADS)

    Repasky, K. S.; Spuler, S.; Nehrir, A. R.; Moen, D.

    2013-12-01

    Water vapor is the most dominant greenhouse gas in the atmosphere and plays an important role in many key atmospheric processes associated with both weather and climate. Water vapor is highly variable in space and time due to large scale transport and biosphere-atmosphere interactions. Having long-term, high-resolution, vertical profiles of water vapor will help to better understand the water vapor structure and variability and its associated impact on weather and climate. A diode laser based differential absorption lidar (DIAL) for full-time water vapor and aerosol profiling in the lower troposphere has been demonstrated at Montana State University. This prototype instrument has the potential to form the basis of a ground based network of eye-safe autonomous instruments that can provide important information on the spatial and temporal variability of water vapor in the lower troposphere. To achieve this potential, major improvements to the prototype instrument need to be implemented and demonstrated including developing a laser transmitter capable of long term operation and modifying the optical receiver to make measurement below 0.5 km. During the past year, work on incorporating a new laser transmitter based on two distributed Bragg reflector (DBR) diode lasers, one operating at the on-line/side-line wavelength and the second operating at the off-line wavelength to injection seed a tapered semiconductor optical amplifier (TSOA) in a master oscillator power amplifier (MOPA) configuration has been completed. Recent work on the optical receiver is driven by the fact that the majority of the atmospheric water vapor resides below 2 km. The current single channel DIAL receiver has a narrow field of view and does not come in to full overlap until approximately 2 km. A two channel DIAL receiver has been designed that will allow the DIAL to achieve full overlap at ranges of less the 0.5 km providing significant improvement to the instrument performance. A discussion of

  18. A search for chemical laser action in low pressure metal vapor flames. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Zwillenberg, M. L.

    1975-01-01

    Optical emissions were studied from low pressure (approximately 1 torr) dilute diffusion flames of Ca and Mg vapor with O2, N2O and mixtures of CCl4 and O2. The Ca flames with O2 and N2O revealed high vibrational excitation of the product CaO molecule (up to v=30). The flames with CCl4 revealed extreme nonequilibrium metal atom electronic excitation, up to the metal atom ionization limit (6.1 eV for Ca, 7.6 eV for Mg). The metal atom excited electronic state populations did not follow a Boltzmann distribution, but the excitation rates ('pumping rate') were found to obey an Arrhenius-type expression, with the electronic excitation energy playing the role of activation energy and a temperature of about 5000 K for triplet excited states and 2500 K for singlets (vs. approximately 500 K translational temperature).

  19. Laser ablation system, and method of decontaminating surfaces

    DOEpatents

    Ferguson, Russell L.; Edelson, Martin C.; Pang, Ho-ming

    1998-07-14

    A laser ablation system comprising a laser head providing a laser output; a flexible fiber optic cable optically coupled to the laser output and transmitting laser light; an output optics assembly including a nozzle through which laser light passes; an exhaust tube in communication with the nozzle; and a blower generating a vacuum on the exhaust tube. A method of decontaminating a surface comprising the following steps: providing an acousto-optic, Q-switched Nd:YAG laser light ablation system having a fiber optically coupled output optics assembly; and operating the laser light ablation system to produce an irradiance greater than 1.times.10.sup.7 W/cm.sup.2, and a pulse width between 80 and 170 ns.

  20. Kr/sup +/ laser-induced chemical vapor deposition of W

    SciTech Connect

    Zhang, G.Q.; Szoerenyi, T.; Baeuerle, D.

    1987-07-15

    Kr/sup +/ laser-induced pyrolytic direct writing of W stripes by H/sub 2/ reduction of WF/sub 6/ has been investigated. The reproducibility of the process and the morphology and electrical properties of deposits depend heavily on the partial pressures of both WF/sub 6/ and H/sub 2/; the best results have been obtained with p(WF/sub 6/) = 5 mbar and 100 mbarless than or equal top(H/sub 2/)less than or equal to800 mbar. For a laser focus of 2w/sub 0/ = 7 ..mu..m and laser powers between 30 and 200 mW, the widths of stripes varied between 1.5 and 15 ..mu..m with corresponding thicknesses between 0.1 to 3 ..mu..m. The width of stripes is independent of the scanning speed within the range 20 ..mu..m/sless than or equal toV/sub s/ less than or equal to400 ..mu..m/s. The electrical resistivities of these stripes were about a factor of 1.3--2.3 larger than the bulk value.

  1. Comparison of three-dimensional retinal imaging methods: the method of scanning laser triangulation.

    PubMed

    Milbocker, M T; Reznichenko, Y M

    1991-10-01

    Three methods of three-dimensional imaging of the vitreous and the fundus of the human eye are compared. Equations are derived for the theoretical depth resolution of stereophotogrammetry, scanning laser tomography, and scanning laser triangulation. Scanning laser triangulation provides superior depth resolution without requiring axial scanning. A description of a prototype scanning laser triangulator is given.

  2. Growth of high quality mercurous halide single crystals by physical vapor transport method for AOM and radiation detection applications

    NASA Astrophysics Data System (ADS)

    Amarasinghe, Priyanthi M.; Kim, Joo-Soo; Chen, Henry; Trivedi, Sudhir; Qadri, Syed B.; Soos, Jolanta; Diestler, Mark; Zhang, Dajie; Gupta, Neelam; Jensen, Janet L.; Jensen, James

    2016-09-01

    Single crystals of mercurous halide were grown by physical vapor transport method (PVT). The orientation and the crystalline quality of the grown crystals were determined using high resolution x-ray diffraction (HRXRD) technique. The full width at half maximum (FWHM) of the grown mercurous bromide crystals was measured to be 0.13 degrees for (004) reflection, which is the best that has been achieved so far for PVT grown mercurous halide single crystals. The extended defects of the crystals were also analyzed using high resolution x-ray diffraction topography. Preliminary studies were carried out to evaluate the performance of the crystals on acousto-optic modulator (AOM) and gamma-ray detector applications. The results indicate the grown mercurous halide crystals are excellent materials for acousto-optic modulator device fabrication. The diffraction efficiencies of the fabricated AOM device with 1152 and 1523 nm wavelength lasers polarizing parallel to the acoustic wave were found to be 35% and 28%, respectively. The results also indicate the grown crystals are a promising material for gamma-ray detector application with a very high energy resolution of 1.86% FWHM.

  3. An Interpolation Method for Obtaining Thermodynamic Properties Near Saturated Liquid and Saturated Vapor Lines

    NASA Technical Reports Server (NTRS)

    Nguyen, Huy H.; Martin, Michael A.

    2004-01-01

    The two most common approaches used to formulate thermodynamic properties of pure substances are fundamental (or characteristic) equations of state (Helmholtz and Gibbs functions) and a piecemeal approach that is described in Adebiyi and Russell (1992). This paper neither presents a different method to formulate thermodynamic properties of pure substances nor validates the aforementioned approaches. Rather its purpose is to present a method to generate property tables from existing property packages and a method to facilitate the accurate interpretation of fluid thermodynamic property data from those tables. There are two parts to this paper. The first part of the paper shows how efficient and usable property tables were generated, with the minimum number of data points, using an aerospace industry standard property package. The second part describes an innovative interpolation technique that has been developed to properly obtain thermodynamic properties near the saturated liquid and saturated vapor lines.

  4. Platinum-ruthenium bimetallic clusters on graphite: a comparison of vapor deposition and electroless deposition methods.

    PubMed

    Galhenage, Randima P; Xie, Kangmin; Diao, Weijian; Tengco, John Meynard M; Seuser, Grant S; Monnier, John R; Chen, Donna A

    2015-11-14

    Bimetallic Pt-Ru clusters have been grown on highly ordered pyrolytic graphite (HOPG) surfaces by vapor deposition and by electroless deposition. These studies help to bridge the material gap between well-characterized vapor deposited clusters and electrolessly deposited clusters, which are better suited for industrial catalyst preparation. In the vapor deposition experiments, bimetallic clusters were formed by the sequential deposition of Pt on Ru or Ru on Pt. Seed clusters of the first metal were grown on HOPG surfaces that were sputtered with Ar(+) to introduce defects, which act as nucleation sites for Pt or Ru. On the unmodified HOPG surface, both Pt and Ru clusters preferentially nucleated at the step edges, whereas on the sputtered surface, clusters with relatively uniform sizes and spatial distributions were formed. Low energy ion scattering experiments showed that the surface compositions of the bimetallic clusters are Pt-rich, regardless of the order of deposition, indicating that the interdiffusion of metals within the clusters is facile at room temperature. Bimetallic clusters on sputtered HOPG were prepared by the electroless deposition of Pt on Ru seed clusters from a Pt(+2) solution using dimethylamine borane as the reducing agent at pH 11 and 40 °C. After exposure to the electroless deposition bath, Pt was selectively deposited on Ru, as demonstrated by the detection of Pt on the surface by XPS, and the increase in the average cluster height without an increase in the number of clusters, indicating that Pt atoms are incorporated into the Ru seed clusters. Electroless deposition of Ru on Pt seed clusters was also achieved, but it should be noted that this deposition method is extremely sensitive to the presence of other metal ions in solution that have a higher reduction potential than the metal ion targeted for deposition.

  5. Laser interference effect evaluation method based on character of laser-spot and image feature

    NASA Astrophysics Data System (ADS)

    Tang, Jianfeng; Luo, Xiaolin; Wu, Lingxia

    2016-10-01

    Evaluating the laser interference effect to CCD objectively and accurately has great research value. Starting from the change of the image's feature before and after interference, meanwhile, considering the influence of the laser-spot distribution character on the masking degree of the image feature information, a laser interference effect evaluation method based on character of laser-spot and image feature was proposed. It reflected the laser-spot distribution character using the distance between the center of the laser-spot and center of the target. It reflected the change of the global image feature using the changes of image's sparse coefficient matrix, which was obtained by the SSIM-inspired orthogonal matching pursuit (OMP) sparse coding algorithm. What's more, the assessment method reflected the change of the local image feature using the changes of the image's edge sharpness, which could be obtained by the change of the image's gradient magnitude. Taken together, the laser interference effect can be evaluated accurately. In terms of the laser interference experiment results, the proposed method shows good rationality and feasibility under the disturbing condition of different laser powers, and it can also overcome the inaccuracy caused by the change of the laser-spot position, realizing the evaluation of the laser interference effect objectively and accurately.

  6. A comparison between protein crystals grown with vapor diffusion methods in microgravity and protein crystals using a gel liquid-liquid diffusion ground-based method

    NASA Technical Reports Server (NTRS)

    Miller, Teresa Y.; He, Xiao-Min; Carter, Daniel C.

    1992-01-01

    Crystals of human serum albumin have been successfully grown in a variety of gels using crystallization conditions otherwise equivalent to those utilized in the popular hanging-drop vapor-equilibrium method. Preliminary comparisons of gel grown crystals with crystals grown by the vapor diffusion method via both ground-based and microgravity methods indicate that crystals superior in size and quality may be grown by limiting solutal convection. Preliminary X-ray diffraction statistics are presented.

  7. Does prostate configuration affect the efficacy and safety of GreenLight HPS™ laser photoselective vaporization prostatectomy (PVP)?

    PubMed

    Gu, Xiao; Strom, Kurt; Spaliviero, Massimiliano; Wong, Carson

    2013-02-01

    We evaluate the efficacy and safety of GreenLight HPS™ laser photoselective vaporization prostatectomy (PVP) for the treatment of benign prostatic hyperplasia (BPH) with different prostate configuration. Patients were stratified into two groups: bilobe (group I) and trilobe (group II) BPH. Transurethral PVP was performed using a 120 W GreenLight HPS™ side-firing laser system. American Urological Association Symptom Score (AUASS), Quality of Life (QoL) score, maximum flow rate (Q max), and postvoid residual (PVR) were measured preoperatively and at 1 and 4 weeks and 3, 6, 12, 18, 24 and 36 months postoperatively. A number of 160 consecutive patients were identified (I: 86, II: 74). Among the preoperative parameters, there were significant differences (p < 0.05) in prostate volume (I: 46.0 ± 19.8; II: 87.5 ± 39.6 ml), Q max (I: 9.9 ± 3.9; II: 8.7 ± 3.5 ml/sec), PVR (I: 59.2 ± 124.6; II: 97.7 ± 119.1 ml) and PSA (I: 1.4 ± 1.4; II: 3.6 ± 2.6 ng/ml), while AUASS and QoL were similar (p > 0.05). Significant differences (p < 0.05) in laser utilization (I: 9.5 ± 6.6; II: 19.5 ± 11.6 min) and energy usage (I: 63.1 ± 43.9; II: 132.5 ± 81.1 kJ) were noted. Clinical outcomes (AUASS, QoL, Q max, and PVR) showed immediate and stable improvement from baseline (p < 0.05) within each group, but no significant differences between the two groups were observed during the follow-up period (p > 0.05). The incidences of adverse events were low and similar in both groups. Our experience suggests that BPH configuration has little effect on the efficacy and safety of GreenLight HPS™ laser PVP.

  8. Venous gas embolism caused by fibrin sealant application to the prostate during greenlight laser photoselective vaporization.

    PubMed

    Lee, Alexander; Vazquez, Rafael

    2015-04-15

    Venous gas embolism is a complication of fibrin sealant application and is a well-described event during various modes of prostate resection. We describe the case of a nitrogen venous gas embolism during Greenlight laser photovaporization of the prostate during the application of fibrin sealant to the operative site for hemostasis. Fibrin sealant application by a compressed gas applicator is a cause of venous air embolism, and this case highlights the need to keep venous gas embolism in mind when compressed gas applicators are used.

  9. Pulsed laser photolysis and quantum chemical-statistical rate study of the reaction of the ethynyl radical with water vapor

    NASA Astrophysics Data System (ADS)

    Carl, Shaun A.; Minh Thi Nguyen, Hue; Elsamra, Rehab M. I.; Tho Nguyen, Minh; Peeters, Jozef

    2005-03-01

    The rate coefficient of the gas-phase reaction C2H+H2O→products has been experimentally determined over the temperature range 500-825K using a pulsed laser photolysis-chemiluminescence (PLP-CL) technique. Ethynyl radicals (C2H) were generated by pulsed 193nm photolysis of C2H2 in the presence of H2O vapor and buffer gas N2 at 15Torr. The relative concentration of C2H radicals was monitored as a function of time using a CH * chemiluminescence method. The rate constant determinations for C2H+H2O were k1(550K)=(2.3±1.3)×10-13cm3s-1, k1(770cm3s-1, and k1(825cm3s-1. The error in the only other measurement of this rate constant is also discussed. We have also characterized the reaction theoretically using quantum chemical computations. The relevant portion of the potential energy surface of C2H3O in its doublet electronic ground state has been investigated using density functional theory B3LYP /6-311++G(3df,2p) and molecular orbital computations at the unrestricted coupled-cluster level of theory that incorporates all single and double excitations plus perturbative corrections for the triple excitations, along with the 6-311++G(3df,2p) basis set [(U)CCSD(T)/6-311++G(3df,2p)] and using UCCSD(T )/6-31G(d,p) optimized geometries. Five isomers, six dissociation products, and sixteen transition structures were characterized. The results confirm that the hydrogen abstraction producing C2H2+OH is the most facile reaction channel. For this channel, refined computations using (U)CCSD(T)/6-311++G(3df,2p)//(U)CCSD(T)/6-311++G(d,p) and complete-active-space second-order perturbation theory/complete-active-space self-consistent-field theory (CASPT2/CASSCF) [B. O. Roos, Adv. Chem. Phys. 69, 399 (1987)] using the contracted atomic natural orbitals basis set (ANO-L) [J. Almlöf and P. R. Taylor, J. Chem. Phys.86, 4070 (1987)] were performed, yielding zero-point energy-corrected potential energy barriers of 17kJmol-1 and 15kJmol-1, respectively. Transition-state theory rate constant

  10. Laser light routing in an elongated micromachined vapor cell with diffraction gratings for atomic clock applications.

    PubMed

    Chutani, Ravinder; Maurice, Vincent; Passilly, Nicolas; Gorecki, Christophe; Boudot, Rodolphe; Abdel Hafiz, Moustafa; Abbé, Philippe; Galliou, Serge; Rauch, Jean-Yves; de Clercq, Emeric

    2015-09-14

    This paper reports on an original architecture of microfabricated alkali vapor cell designed for miniature atomic clocks. The cell combines diffraction gratings with anisotropically etched single-crystalline silicon sidewalls to route a normally-incident beam in a cavity oriented along the substrate plane. Gratings have been specifically designed to diffract circularly polarized light in the first order, the latter having an angle of diffraction matching the (111) sidewalls orientation. Then, the length of the cavity where light interacts with alkali atoms can be extended. We demonstrate that a longer cell allows to reduce the beam diameter, while preserving the clock performances. As the cavity depth and the beam diameter are reduced, collimation can be performed in a tighter space. This solution relaxes the constraints on the device packaging and is suitable for wafer-level assembly. Several cells have been fabricated and characterized in a clock setup using coherent population trapping spectroscopy. The measured signals exhibit null power linewidths down to 2.23 kHz and high transmission contrasts up to 17%. A high contrast-to-linewidth ratio is found at a linewidth of 4.17 kHz and a contrast of 5.2% in a 7-mm-long cell despite a beam diameter reduced to 600 μm.

  11. Laser light routing in an elongated micromachined vapor cell with diffraction gratings for atomic clock applications

    PubMed Central

    Chutani, Ravinder; Maurice, Vincent; Passilly, Nicolas; Gorecki, Christophe; Boudot, Rodolphe; Abdel Hafiz, Moustafa; Abbé, Philippe; Galliou, Serge; Rauch, Jean-Yves; de Clercq, Emeric

    2015-01-01

    This paper reports on an original architecture of microfabricated alkali vapor cell designed for miniature atomic clocks. The cell combines diffraction gratings with anisotropically etched single-crystalline silicon sidewalls to route a normally-incident beam in a cavity oriented along the substrate plane. Gratings have been specifically designed to diffract circularly polarized light in the first order, the latter having an angle of diffraction matching the (111) sidewalls orientation. Then, the length of the cavity where light interacts with alkali atoms can be extended. We demonstrate that a longer cell allows to reduce the beam diameter, while preserving the clock performances. As the cavity depth and the beam diameter are reduced, collimation can be performed in a tighter space. This solution relaxes the constraints on the device packaging and is suitable for wafer-level assembly. Several cells have been fabricated and characterized in a clock setup using coherent population trapping spectroscopy. The measured signals exhibit null power linewidths down to 2.23 kHz and high transmission contrasts up to 17%. A high contrast-to-linewidth ratio is found at a linewidth of 4.17 kHz and a contrast of 5.2% in a 7-mm-long cell despite a beam diameter reduced to 600 μm. PMID:26365754

  12. IC Fabrication Methods Improve Laser Diodes

    NASA Technical Reports Server (NTRS)

    Miller, M.; Pickhardt, V.

    1984-01-01

    Family of high-performance, tunable diode lasers developed for use as local oscillators in passive laser heterodyne spectrometer. Diodes fabricated using standard IC processes include photolithography, selective etching and vacuum deposition of metals and insulators. Packaging refinements improved thermal-cycling characteristics of diodes and increased room-temperature shelf life.

  13. A quantum cascade laser-based water vapor isotope analyzer for environmental monitoring

    SciTech Connect

    Wang, W. E.; Tsai, T.; Wysocki, G.; Michel, A. P. M.; Wang, L.; Baeck, M. L.; Smith, J. A.

    2014-09-15

    A field-deployable mid-infrared quantum cascade laser-based spectrometer was designed and developed for measurements of H{sub 2}{sup 16}O and H{sub 2}{sup 18}O at 7.12 μm. H{sub 2}{sup 16}O and H{sub 2}{sup 18}O absorption features at 1390.52 cm{sup −1} and 1389.91 cm{sup −1}, respectively, accessible within current tuning range of the laser, were targeted. The target lines were carefully selected to assure similar absorption levels and similar temperature sensitivities of the line strength due to comparable lower state energies. A real-time spectral fitting algorithm was implemented for isotopic concentration retrieval. Detection limits for H{sub 2}{sup 16}O and H{sub 2}{sup 18}O of 2.2 ppm and 7.0 ppb, respectively, were achieved at a dew point of 14 °C (volume mixing ratio of 15 766 ppm) in 1 s integration time, which resulted in a δ{sup 18}O isotopic ratio measurement precision of 0.25‰. The ultimate minimum detection limits obtained after 160 s integration time for H{sub 2}{sup 16}O and H{sub 2}{sup 18}O, and δ{sup 18}O measurements were 0.6 ppm, 1.7 ppb, and 0.05‰, respectively.

  14. Chemical models for simulating single-walled nanotube production in arc vaporization and laser ablation processes

    NASA Technical Reports Server (NTRS)

    Scott, Carl D.

    2004-01-01

    Chemical kinetic models for the nucleation and growth of clusters and single-walled carbon nanotube (SWNT) growth are developed for numerical simulations of the production of SWNTs. Two models that involve evaporation and condensation of carbon and metal catalysts, a full model involving all carbon clusters up to C80, and a reduced model are discussed. The full model is based on a fullerene model, but nickel and carbon/nickel cluster reactions are added to form SWNTs from soot and fullerenes. The full model has a large number of species--so large that to incorporate them into a flow field computation for simulating laser ablation and arc processes requires that they be simplified. The model is reduced by defining large clusters that represent many various sized clusters. Comparisons are given between these models for cases that may be applicable to arc and laser ablation production. Solutions to the system of chemical rate equations of these models for a ramped temperature profile show that production of various species, including SWNTs, agree to within about 50% for a fast ramp, and within 10% for a slower temperature decay time.

  15. Growth dynamics of carbon-metal particles and nanotubes synthesized by CO2 laser vaporization

    NASA Astrophysics Data System (ADS)

    Kokai, F.; Takahashi, K.; Yudasaka, M.; Iijima, S.

    To study the growth of carbon-Co/Ni particles and single-wall carbon nanotubes (SWNTs) by 20 ms CO2 laser-pulse irradiation of a graphite-Co/Ni (1.2 at.%) target in an Ar gas atmosphere (600 Torr), we used emission imaging spectroscopy and shadowgraphy with a temporal resolution of 1.67 ms. Wavelength-selected emission images showed that C2 emission was strong in the region close to the target (within 2 cm), while for the same region the blackbody radiation from the large clusters or particles increased with increasing distance from the target. Shadowgraph images showed that the viscous flow of carbon and metal species formed a mushroom or a turbulent cloud spreading slowly into the Ar atmosphere, indicating that particles and SWNTs continued to grow as the ejected material cooled. In addition, emission imaging spectroscopy at 1200 °C showed that C2 and hot clusters and particles with higher emission intensities were distributed over much wider areas. We discuss the growth dynamics of the particles and SWNTs through the interaction of the ambient Ar with the carbon and metal species released from the target by the laser pulse.

  16. Vapor cell based sodium laser guide star mechanism study lab-bench

    NASA Astrophysics Data System (ADS)

    Wang, Hongyan; Li, Lihang; Luo, Ruiyao; Li, Lei; Ning, Yu; Xi, Fengjie; Xu, Xiaojun

    2016-07-01

    Sodium laser guide star (LGS) is the key for the success of modern adaptive optics (AO) supported large ground based telescopes, however, for many field applications, Sodium LGS's brightness is still a limited factor. Large amounts of theoretical efforts have been paid to optimize Sodium LGS exciting parameters, that is, to fully discover potential of harsh environment surrounding mesospheric extreme thin sodium atoms under resonant excitation, whether quantum or Monte Carlo based. But till to now, only limited proposals are demonstrated with on-sky test due to the high cost and engineering complexities. To bridge the gap between theoretical modeling and on-sky test, we built a magnetic field controllable sodium cell based lab-bench, which includes a small scale sum-frequency single mode 589nm laser, with added amplitude, polarization, and phase modulators. We could perform quantitative resonant fluorescence study under single, multi-frequency, side-band optical re-pumping exciting with different polarization, also we could perform optical field modulation to study Larmor precession which is considered as one of devils of Sodium LGS, and we have the ability to generate beams contain orbital angular moment. Our preliminary sodium cell based optical re-pumping experiments have shown excellent consistence with Bloch equation predicted results, other experimental results will also be presented in the report, and these results will give a direct support that sodium cell based lab-bench study could help a Sodium LGS scientists a lot before their on-sky test.

  17. Hydrogen isotope correction for laser instrument measurement bias at low water vapor concentration using conventional isotope analyses: application to measurements from Mauna Loa Observatory, Hawaii.

    PubMed

    Johnson, L R; Sharp, Z D; Galewsky, J; Strong, M; Van Pelt, A D; Dong, F; Noone, D

    2011-03-15

    The hydrogen and oxygen isotope ratios of water vapor can be measured with commercially available laser spectroscopy analyzers in real time. Operation of the laser systems in relatively dry air is difficult because measurements are non-linear as a function of humidity at low water concentrations. Here we use field-based sampling coupled with traditional mass spectrometry techniques for assessing linearity and calibrating laser spectroscopy systems at low water vapor concentrations. Air samples are collected in an evacuated 2 L glass flask and the water is separated from the non-condensable gases cryogenically. Approximately 2 µL of water are reduced to H(2) gas and measured on an isotope ratio mass spectrometer. In a field experiment at the Mauna Loa Observatory (MLO), we ran Picarro and Los Gatos Research (LGR) laser analyzers for a period of 25 days in addition to periodic sample collection in evacuated flasks. When the two laser systems are corrected to the flask data, they are strongly coincident over the entire 25 days. The δ(2)H values were found to change by over 200‰ over 2.5 min as the boundary layer elevation changed relative to MLO. The δ(2)H values ranged from -106 to -332‰, and the δ(18)O values (uncorrected) ranged from -12 to -50‰. Raw data from laser analyzers in environments with low water vapor concentrations can be normalized to the international V-SMOW scale by calibration to the flask data measured conventionally. Bias correction is especially critical for the accurate determination of deuterium excess in dry air.

  18. 975nm high-peak power ns-diode laser based MOPA system suitable for water vapor DIAL applications

    NASA Astrophysics Data System (ADS)

    Sumpf, Bernd; Klehr, Andreas; Vu, Thi Nghiem; Erbert, Götz; Tränkle, Günther

    2015-03-01

    Micro-DIAL (differential absorption LIDAR) systems require light sources with peak powers in the range of several 10 W together with a spectral line width smaller than the width of absorption lines under study. For water vapor at atmospheric pressure this width should be smaller than 10 pm at 975 nm. In this paper, an all semiconductor master oscillator power amplifier system at an emission wavelength of 975 nm will be presented. This spectral range was selected with respect to a targeted absorption path length of 5000 m and H2O line strengths. A distributed feedback (DFB) ridge waveguide diode laser operated in continuous wave is used as master oscillator whereas a tapered amplifier consisting of a RW section and a flared section is implemented as power amplifier. The RW section acts as optical gate. The current pulses injected into the RW part have a length of 8 ns and the tapered part is driven with 15 ns long pulses. The delay between the pulses is adjusted for optimal pulse shape. The repetition rate is in both cases 25 kHz. A maximal pulse output power of about 16 W limited by the available current supply is achieved. The spectral line width of the system determined by the properties of the DFB laser is smaller than 10 pm. The tuning range amounts 0.9 nm and a SMSR of 40 dB is observed. From the dependence of the peak power on the power injected into the tapered amplifier, the saturation power is determined to 5.3 mW.

  19. Answer to Critical Remarks or one More Time About the Mechanism of Limitation on the Energy Characteristics of a Copper Vapor Laser

    NASA Astrophysics Data System (ADS)

    Yudin, N. A.

    2014-05-01

    This work presents an additional analysis of the main positions of the publication by N. A. Yudin, M. R. Tret'yakova, and N. N. Yudin, "Influence of electrophysical processes in the discharge circuit on the energy characteristics of a copper vapor laser" (Russ. Phys. J., 55, No. 9, 1080 - 1090 (2013)) in response to the conclusion drawn in the work of P. A. Bokhan "On the question of the existence of high-frequency oscillations in the power supply circuits of a copper vapor laser and their influence on the lasing mechanism" (Russ. Phys. J., 57, No. 1, 124 - 127 (2014)) that the main positions of the given publication are in error. The analysis performed here confirms the validity of the main positions of publication [2].

  20. Development of polishing methods for Chemical Vapor Deposited Silicon Carbide mirrors for synchrotron radiation

    SciTech Connect

    Fuchs, B.A.; Brown, N.J.

    1987-01-01

    Material properties of Chemical Vapor Deposited Silicon Carbide (CVD SiC) make it ideal for use in mirrors for synchrotron radiation experiments. We developed methods to grind and polish flat samples of CVD SiC down to measured surface roughness values as low as 1.1 Angstroms rms. We describe the processing details, including observations we made during trial runs with alternative processing recipes. We conclude that pitch polishing using progressively finer diamond abrasive, augmented with specific water based lubricants and additives, produces superior results. Using methods based on these results, a cylindrical and a toroidal mirror, each about 100 x 300mm, were respectively finished by Continental Optical and Frank Cooke, Incorporated. WYCO Interferometry shows these mirrors have surface roughness less than 5.7 Angstroms rms. These mirrors have been installed on the LLNL/UC X-ray Calibration and Standards Facility at the Stanford Synthrotron Radiation Laboratory.

  1. Growth of well-oriented VACNTs using thermal chemical vapor deposition method

    NASA Astrophysics Data System (ADS)

    Yousefi, Amin Termeh; Mahmood, Mohamad Rusop; Ikeda, Shoichiro

    2016-07-01

    The remarkable properties of carbon nanotubes (CNTs) make them attractive for biosensor applications, especially for medical detecting devices. In this paper, we describe a process to grow high oriented ratio CNT arrays to improve the electrical properties of the devices based on CNTs. Chemical vapor deposition (CVD) was used to grow highly oriented CNT using camphor as the carbon source, and argon and hydrogen as carrier gases to grow perpendicular CNTs on the surface of the silicon substrate in presence of ferrocene as a metallic catalyst. Images were revealed by FESEM indicates that the formation mechanism of oriented CNTs with high morphological purity nanotubes, which is depends significantly on deposition time and applied temperature to the furnaces. This method might be an effective method to produce oriented MWCNT in different length.

  2. Faraday effect of polycrystalline bismuth iron garnet thin film prepared by mist chemical vapor deposition method

    NASA Astrophysics Data System (ADS)

    Yao, Situ; Kamakura, Ryosuke; Murai, Shunsuke; Fujita, Koji; Tanaka, Katsuhisa

    2017-01-01

    We have synthesized polycrystalline thin film composed of a single phase of metastable bismuth iron garnet, Bi3Fe5O12, on a fused silica substrate, one of the most widely utilized substrates in the solid-state electronics, by using mist chemical vapor deposition (mist CVD) method. The phase purity and stoichiometry are confirmed by X-ray diffraction and Rutherford backscattering spectrometry. The resultant thin film shows a small surface roughness of 3.251 nm. The saturation magnetization at room temperature is 1200 G, and the Faraday rotation angle at 633 nm reaches -5.2 deg/μm. Both the magnetization and the Faraday rotation angles are somewhat higher than those of polycrystalline BIG thin films prepared by other methods.

  3. Simultaneous imaging of fuel vapor mass fraction and gas-phase temperature inside gasoline sprays using two-line excitation tracer planar laser-induced fluorescence.

    PubMed

    Zigan, Lars; Trost, Johannes; Leipertz, Alfred

    2016-02-20

    This paper reports for the first time, to the best of our knowledge, on the simultaneous imaging of the gas-phase temperature and fuel vapor mass fraction distribution in a direct-injection spark-ignition (DISI) spray under engine-relevant conditions using tracer planar laser-induced fluorescence (TPLIF). For measurements in the spray, the fluorescence tracer 3-pentanone is added to the nonfluorescent surrogate fuel iso-octane, which is excited quasi-simultaneously by two different excimer lasers for two-line excitation LIF. The gas-phase temperature of the mixture of fuel vapor and surrounding gas and the fuel vapor mass fraction can be calculated from the two LIF signals. The measurements are conducted in a high-temperature, high-pressure injection chamber. The fluorescence calibration of the tracer was executed in a flow cell and extended significantly compared to the existing database. A detailed error analysis for both calibration and measurement is provided. Simultaneous single-shot gas-phase temperature and fuel vapor mass fraction fields are processed for the assessment of cyclic spray fluctuations.

  4. On the Question of the Existence of High-Frequency Oscillations in the Power Supply Circuits of a Copper Vapor Laser and Their Influence on the Lasing Mechanism

    NASA Astrophysics Data System (ADS)

    Bokhan, P. A.

    2014-05-01

    The statement of the problem and conclusions in the publication by N. A. Yudin, M. R. Tret'yakova, and N. N. Yudin "Influence of electrophysical processes in the discharge circuit on the energy characteristics of a copper vapor laser" (Russ. Phys. J., 55, No. 9, 1080 - 1090 (2013)) is considered. It is shown that the main positions of the publication touching on relaxation of the populations of metastable states in the afterglow and their influence on the frequency-energy characteristics of lasers are mistaken.

  5. Vaporization and deposition of an intact polyimide precursor by resonant infrared pulsed laser ablation

    NASA Astrophysics Data System (ADS)

    Dygert, N. L.; Schriver, K. E.; Haglund, R. F., Jr.

    2006-02-01

    Poly(amic acid) (PAA), a precursor to polyimide, was successfully deposited on substrates without reaching curing temperature, by resonant infrared pulsed laser ablation. The PAA was prepared by dissolving pyromellitic dianhydride and 4, 4' oxidianiline in the polar solvent N-methyl pyrrolidinone (NMP). RIR-PLD transferred material showed two distinct geometries, droplets and string-like moieties. The unaltered nature of the deposited PAA was confirmed by Fourier transform infrared spectroscopy (FTIR). Thermal curing was achieved by heating for one hour on a 250°C hotplate, and the transformation to polyimide was demonstrated from changes in the FTIR spectrum following curing. Plume shadowgraphy showed very clear contrasts in the ablation mechanism between ablation of the solvent alone and the ablation of the PAA, with additional contrast shown between the various resonant frequencies used.

  6. Forced convection and transport effects during hyperbaric laser chemical vapor deposition

    SciTech Connect

    Maxwell, James L; Chavez, Craig A; Espinoza, Miguel; Black, Marcie; Maskaly, Karlene; Boman, Mats

    2009-01-01

    This work explores mass transport processes during HP-LCYD, including the transverse forced-flow of precursor gases through a nozzle to enhance fiber growth rates. The use of laser trapping and suspension of nano-scale particles in the precursor flow is also described, providing insights into the nature of the gas flow, including jetting from the fiber tip and thermodiffusion processes near the reaction zone. The effects of differing molecular-weight buffer gases is also explored in conjunction with the Soret effect, and it is found that nucleation at the deposit surface (and homogeneous nucleation in the gas phase) can be enhanced/ retarded, depending on the buffer gas molecular weight. To demonstrate that extensive microstructures can be grown simultaneously, three-dimensional fiber arrays are also grown in-parallel using diffractive optics--without delatory effects from neighboring reaction sites.

  7. High Temperature Nanocomposites For Nuclear Thermal Propulsion and In-Space Fabrication by Hyperbaric Pressure Laser Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Maxwell, J. L.; Webb, N. D.; Espinoza, M.; Cook, S.; Houts, M.; Kim, T.

    Nuclear Thermal Propulsion (NTP) is an indispensable technology for the manned exploration of the solar system. By using Hyperbaric Pressure Laser Chemical Vapor Deposition (HP-LCVD), the authors propose to design and build a promising next-generation fuel element composed of uranium carbide UC embedded in a latticed matrix of highly refractory Ta4HfC5 for an NTP rocket capable of sustaining temperatures up to 4000 K, enabling an Isp of up to 1250 s. Furthermore, HP-LCVD technology can also be harnessed to enable 3D rapid prototyping of a variety of materials including metals, ceramics and composites, opening up the possibility of in-space fabrication of components, replacement parts, difficult-to-launch solar sails and panels and a variety of other space structures. Additionally, rapid prototyping with HP-LCVD makes a feasible "live off the land" strategy of interplanetary and interstellar exploration ­ the precursors commonly used in the technology are found, often in abundance, on other solar system bodies either as readily harvestable gas (e.g. methane) or as a raw material that could be converted into a suitable precursor (e.g. iron oxide into ferrocene on Mars).

  8. Detection of carbon-fluorine bonds in organofluorine compounds by Raman spectroscopy using a copper-vapor laser

    NASA Astrophysics Data System (ADS)

    Sharts, Clay M.; Gorelik, Vladimir S.; Agoltsov, A. M.; Zlobina, Ludmila I.; Sharts, Olga N.

    1999-02-01

    The Raman spectra of fluoro-organic compounds show specific emission bands for carbon-fluorine bonds in the range 500- 800 wave numbers (cm-1)). With very limited exceptions, biological materials do not contain carbon- fluorine bonds. Fluoro-organic compounds introduced into biological samples can be detected by a Raman emission signal. Normal mode C-F bond bands are observed: (1) at 710- 785 cm -1 for trifluoromethyl groups; (2) at 530-610 cm -1 for aromatic organofluorine bonds; (3) a range centered at 690 cm -1 for difluoromethylene groups. Specific examples of normal mode C-F bond emissions for organofluorine compounds containing trifluoromethyl groups are: 1-bromoperfluorooctane, 726 cm -1; perfluorodecanoic acid, 730 cm -1; triperfluoropropylamine, 750 cm -1; 1,3,5-tris- (trifluoromethyl)-benzene, 730 cm -1; Fluoxetine (Prozac) commercial powdered pill at 782 cm -1. Compounds containing aromatic C-F bonds are: hexafluorobenzene, 569 cm MIN1; pentafluoropyridine, 589 cm -1. Difluoromethylene groups: perfluorodecalin, 692 cm-1; perfluorocyclohexane, 691 cm -1. Raman spectra were observed with a standard single monochromator. The 510.8 nm light source was a copper-vapor laser operated at 3-10 watts with 10-12 nanosecond pulses at 10 kHz repetition rate. Detection was made with a time-gated photomultiplier tube. Resonance Raman spectra were also observed at 255.4 nm, using a frequency doubling crystal. Observed spectra were free of fluorescence with very sharp strong C-F lines.

  9. Calibrated vapor generator source

    DOEpatents

    Davies, J.P.; Larson, R.A.; Goodrich, L.D.; Hall, H.J.; Stoddard, B.D.; Davis, S.G.; Kaser, T.G.; Conrad, F.J.

    1995-09-26

    A portable vapor generator is disclosed that can provide a controlled source of chemical vapors, such as, narcotic or explosive vapors. This source can be used to test and calibrate various types of vapor detection systems by providing a known amount of vapors to the system. The vapor generator is calibrated using a reference ion mobility spectrometer. A method of providing this vapor is described, as follows: explosive or narcotic is deposited on quartz wool, placed in a chamber that can be heated or cooled (depending on the vapor pressure of the material) to control the concentration of vapors in the reservoir. A controlled flow of air is pulsed over the quartz wool releasing a preset quantity of vapors at the outlet. 10 figs.

  10. Calibrated vapor generator source

    DOEpatents

    Davies, John P.; Larson, Ronald A.; Goodrich, Lorenzo D.; Hall, Harold J.; Stoddard, Billy D.; Davis, Sean G.; Kaser, Timothy G.; Conrad, Frank J.

    1995-01-01

    A portable vapor generator is disclosed that can provide a controlled source of chemical vapors, such as, narcotic or explosive vapors. This source can be used to test and calibrate various types of vapor detection systems by providing a known amount of vapors to the system. The vapor generator is calibrated using a reference ion mobility spectrometer. A method of providing this vapor is described, as follows: explosive or narcotic is deposited on quartz wool, placed in a chamber that can be heated or cooled (depending on the vapor pressure of the material) to control the concentration of vapors in the reservoir. A controlled flow of air is pulsed over the quartz wool releasing a preset quantity of vapors at the outlet.

  11. Improvement of the antifungal activity of Litsea cubeba vapor by using a helium-neon (He-Ne) laser against Aspergillus flavus on brown rice snack bars.

    PubMed

    Suhem, Kitiya; Matan, Narumol; Matan, Nirundorn; Danworaphong, Sorasak; Aewsiri, Tanong

    2015-12-23

    The aim of this study was to improve the antifungal activity of the volatile Litsea cubeba essential oil and its main components (citral and limonene) on brown rice snack bars by applying He-Ne laser treatment. Different volumes (50-200 μL) of L. cubeba, citral or limonene were absorbed into a filter paper and placed inside an oven (18 L). Ten brown rice snack bars (2 cm wide × 4 cm long × 0.5 cm deep) were put in an oven and heated at 180 °C for 20 min. The shelf-life of the treated snack bars at 30 °C was assessed and sensory testing was carried out to investigate their consumer acceptability. A count of total phenolic content (TPC) and Fourier transform infrared spectroscopy (FTIR) on the properties of essential oil, citral, and limonene before and after the laser treatment was studied for possible modes of action. It was found that the laser treatment improved the antifungal activity of the examined volatile L. cubeba and citral with Aspergillus flavus inhibition by 80% in comparison with those of the control not treated with the laser. L. cubeba vapor at 100 μL with the laser treatment was found to completely inhibit the growth of natural molds on the snack bars for at least 25 days; however, without essential oil vapor and laser treatment, naturally contaminating mold was observed in 3 days. Results from the sensory tests showed that the panelists were unable to detect flavor and aroma differences between essential oil treatment and the control. Laser treatment caused an increase in TPC of citral oil whereas the TPC in limonene showed a decrease after the laser treatment. These situations could result from the changing peak of the aliphatic hydrocarbons that was revealed by the FTIR spectra.

  12. Method for foam encapsulating laser targets

    DOEpatents

    Hendricks, Charles D.

    1977-01-01

    Foam encapsulated laser fusion targets are made by positioning a fusion fuel-filled sphere within a mold cavity of suitable configuration and dimensions, and then filling the cavity with a material capable of producing a low density, microcellular foam, such as cellulose acetate dissolved in an acetone-based solvent. The mold assembly is dipped into an ice water bath to gel the material and thereafter soaked in the water bath to leach out undesired components, after which the gel is frozen, then freeze-dried wherein water and solvents sublime and the gel structure solidifies into a low-density microcellular foam, thereafter the resulting foam encapsulated target is removed from the mold cavity. The fuel-filled sphere is surrounded by foam having a thickness of about 10 to 100 .mu.m, a cell size of less than 2 .mu.m, and density of 0.065 to 0.6 .times. 10.sup.3 kg/m.sup.3. Various configured foam-encapsulated targets capable of being made by this encapsulation method are illustrated.

  13. Fiber-optic-based laser vapor screen flow visualization system for aerodynamic research in larger scale subsonic and transonic wind tunnels

    NASA Technical Reports Server (NTRS)

    Erickson, Gary E.; Inenaga, Andrew S.

    1994-01-01

    Laser vapor screen (LVS) flow visualization systems that are fiber-optic based were developed and installed for aerodynamic research in the Langley 8-Foot Transonic Pressure Tunnel and the Langley 7- by 10-Foot High Speed Tunnel. Fiber optics are used to deliver the laser beam through the plenum shell that surrounds the test section of each facility and to the light-sheet-generating optics positioned in the ceiling window of the test section. Water is injected into the wind tunnel diffuser section to increase the relative humidity and promote condensation of the water vapor in the flow field about the model. The condensed water vapor is then illuminated with an intense sheet of laser light to reveal features of the flow field. The plenum shells are optically sealed; therefore, video-based systems are used to observe and document the flow field. Operational experience shows that the fiber-optic-based systems provide safe, reliable, and high-quality off-surface flow visualization in smaller and larger scale subsonic and transonic wind tunnels. The design, the installation, and the application of the Langley Research Center (LaRC) LVS flow visualization systems in larger scale wind tunnels are highlighted. The efficiency of the fiber optic LVS systems and their insensitivity to wind tunnel vibration, the tunnel operating temperature and pressure variations, and the airborne contaminants are discussed.

  14. Comparison of methods for the measurement of mist and vapor from light mineral oil-based metalworking fluids.

    PubMed

    Simpson, Andrew T

    2003-11-01

    The measurement of oil mist derived from metalworking fluids formulated with light mineral oils can be highly inaccurate when using traditional filter sampling. This is due to evaporation of oil from the filter. In this work the practicability of an alternative approach measuring total oil mist and vapor was investigated. Combinations of inhalable particle samplers with backup sorbent vapor traps and standard vapor sampling on pumped and diffusive sorbent tubes were evaluated with gravimetric, infrared spectroscopic, and gas chromatographic analytical methods against the performance requirements of European Standard EN 482. An artificial aerosol was used to compare the methods against a reference method of filter sampler in series with three impingers. Multi-orifice samplers were used with standard 8-mm diameter charcoal tubes at 2 L/min without any signs of channelling or significant breakthrough, as were conical inhalable samplers with XAD-2 tubes at 1 L/min. Most combinations of samplers had a bias of less than 3 percent, but solitary pumped charcoal tubes underestimated total oil by 13 percent. Diffusive sampling was affected by impaction of mist particles and condensation of oil vapor. Gravimetric analysis of filters revealed significant potential sample loss during storage, with 4 percent being lost after one day when stored at room temperature and 2 percent when refrigerated. Samples left overnight in the balance room to equilibrate lost 24 percent. Infrared spectroscopy gave more precise results for vapor than gas chromatography (p = 0.002). Gas chromatography was less susceptible to bias from contaminating solvent vapors than infrared spectroscopy, but was still vulnerable to petroleum distillates. Under the specific test conditions (one oil type and mist particle size), all combinations of methods examined complied with the requirements of European Standard EN 484. Total airborne oil can be measured accurately; however, care must be taken to avoid

  15. A method for detecting breakthrough of organic solvent vapors in a charcoal tube using semiconductor gas sensors

    SciTech Connect

    Hori, Hajime; Noritake, Yuji; Murobushi, Hisako; Higashi, Toshiaki; Tanaka, Isamu

    1999-08-01

    This study developed a method for detecting organic vapors that break through charcoal tubes, using semiconductor gas sensors as a breakthrough detector of vapors. A glass column equipped with two sensors was inserted in Teflon tubing, and air containing organic vapor was introduced at a constant flow rate. After the output signal of the sensors became stable, a charcoal tube was inserted into the tubing at the upstream of the sensors. The resistance of the sensors was collected temporally in an integrated circuit (IC) card. The vapor concentration of the air near the sensors was measured with a gas chromatograph (GC) equipped with a flame ionization detector (FID) at intervals of 5 minutes to obtain the breakthrough curve. When the relative humidity was zero, the output signals of the sensors began to change before the breakthrough point (1% breakthrough time). This tendency was almost the same for methyl acetate, ethyl acetate, isopropyl alcohol (IPA), toluene, and chloroform. For dichloromethane and 1,1,1-trichloroethane, the time when the sensor output signals began to rise was almost the same as the breakthrough point. When the relative humidity was 80 percent, the sensors could also detect many vapors before the breakthrough point, but they could not perceive dichloromethane and chloroform vapors. A personal sampling system with a breakthrough detector was developed and its availability is discussed.

  16. The Vapor Pressure of Environmentally Significant Organic Chemicals: A Review of Methods and Data at Ambient Temperature

    NASA Astrophysics Data System (ADS)

    Delle Site, Alessandro

    1997-01-01

    The experimental techniques and the prediction procedures for the determination or evaluation of the vapor pressure of environmentally relevant organic compounds are described; with 259 references examined. For each of them the characteristics of precision and accuracy are given, when available from the literature. The experimental methods are classified as "direct" and "indirect." The first class includes all those which can measure directly the vapor pressure, while the second concerns those which need "known" vapor pressures of reference compounds for the calibration. Prediction methods are based on the application of the Clapeyron-Clausius equation or on the quantitative structure-property relationships. Also correlation methods require a suitable calibration. The vapor pressures at ambient temperature for several polycyclic aromatic hydrocarbons, polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and furans, selected pesticides, and some reference compounds are tabulated together with the vapor pressure equations and the enthalpy values in the temperature range of measurement. A critical comparison, based on a statistical analysis of the data obtained with different methods and derived from 152 references, is also carried out.

  17. System, Apparatus and Method Employing a Dual Head Laser

    NASA Technical Reports Server (NTRS)

    Coyle, Donald B. (Inventor); Stysley, Paul R. (Inventor); Poulios, Demetrios (Inventor)

    2015-01-01

    A system, apparatus and method employing a laser with a split-head, V-assembly gain material configuration. Additionally, the present invention is directed to techniques to better dissipate or remove unwanted energies in laser operations. The present invention is also directed to techniques for better collimated laser beams, with single spatial mode quality (TEM00), with improved efficiency, in extreme environments, such as in outer space.

  18. Ambient methods and apparatus for rapid laser trace constituent analysis

    DOEpatents

    Snyder, Stuart C.; Partin, Judy K.; Grandy, Jon D.; Jeffery, Charles L.

    2002-01-01

    A method and apparatus are disclosed for measuring trace amounts of constituents in samples by using laser induced breakdown spectroscopy and laser induced fluorescence under ambient conditions. The laser induced fluorescence is performed at a selected wavelength corresponding to an absorption state of a selected trace constituent. The intensity value of the emission decay signal which is generated by the trace constituent is compared to calibrated emission intensity decay values to determine the amount of trace constituent present.

  19. Targeted Nanoparticle Thermometry: A Method to Measure Local Temperature at the Nanoscale Point Where Water Vapor Nucleation Occurs.

    PubMed

    Alaulamie, Arwa A; Baral, Susil; Johnson, Samuel C; Richardson, Hugh H

    2017-01-01

    An optical nanothermometer technique based on laser trapping, moving and targeted attaching an erbium oxide nanoparticle cluster is developed to measure the local temperature. The authors apply this new nanoscale temperature measuring technique (limited by the size of the nanoparticles) to measure the temperature of vapor nucleation in water. Vapor nucleation is observed after superheating water above the boiling point for degassed and nondegassed water. The average nucleation temperature for water without gas is 560 K but this temperature is lowered by 100 K when gas is introduced into the water. The authors are able to measure the temperature inside the bubble during bubble formation and find that the temperature inside the bubble spikes to over 1000 K because the heat source (optically-heated nanorods) is no longer connected to liquid water and heat dissipation is greatly reduced.

  20. Application of LAMBDA Method to the Calculation of Slant Path Wet Vapor Content of GPS Signals

    NASA Astrophysics Data System (ADS)

    Huang, Shan-Qi; Wang, Jie-Xian; Wang, Xiao-Ya; Chen, Jun-Ping

    2009-10-01

    With the improvement of the GPS data processing techniques and calculating accuracy, the GPS has been increasingly and widely applied to atmospheric science. In the research on GPS meteorology the slant path wet vapor content (SWV) is one of the significant parameters. In the light of the problem of poorer real time, which existed in the method proposed by Song Shuli et al. in 2004, for directly calculating the SWV by means of the precise ephemeris, IGS clock error and observed value of the LC combination after the cycle skip processing, the LAMBDA method which has more mature application to the city virtual reference station (VRS) is applied to the problem of the processing of ambiguity search. Through the trial calculation of data, it is tested and verified that the method is feasible and there is a better uniformity when the calculated result is projected into the zenith direction. The atmospheric delay in the vertical direction obtained by using this method is compared with the result of the GAMIT or the BERNESE, with the result showing that the accuracy of the coincidence of the result of the method with that of the BERNESE is generally smaller than 1.5 cm and the accuracy of the coincidence of the result of the method with that of the GAMIT is generally smaller than 10 cm.

  1. Capillary stability of vapor-liquid-solid crystallization processes and their comparison to Czochralski and Stepanov growth methods

    NASA Astrophysics Data System (ADS)

    Nebol'sin, Valery A.; Suyatin, Dmitry B.; Dunaev, Alexander I.; Tatarenkov, Alexander F.

    2017-04-01

    Epitaxial semiconductor nanowires grown with vapor-liquid-solid crystallization processes are very attractive nanoscale objects for many different applications. Despite extensive studies of the growth mechanism, there is still a lack of understanding of the growth process; in particular, the stability of the vapor-liquid-solid crystallization process has not previously been studied. Here we examine the capillary stability of the vapor-liquid-solid growth of nanowires and filamentary crystals with different diameters and demonstrate that the growth is stable for small Bond numbers when the meniscus height is linearly dependent on catalyst diameter. The capillary stability of vapor-liquid-solid growth is also compared with capillary stability in the Stepanov and Czochralski crystal growth methods; it is shown that capillary stability is not possible in the Czochralski method, although it is possible in the Stepanov growth method when the ratio of crystal diameter to shaper diameter is >1/2. These findings are important for better understanding and improved control of the growth of nanowires and filamentary crystals and indicate, for example, that large diameter filamentary crystals can be grown via a vapor-liquid-solid mechanism if the influence of gravity forces on the liquid catalytic particle shape can be reduced.

  2. An investigation of vapor concentration during boiling of liquid mixtures

    SciTech Connect

    Utaka, Yoshio; Takahashi, Katsuaki; Tsuboi, Takao

    1999-07-01

    The objective of the study is to clarify experimentally the variation of the vapor concentration of binary mixture generated during nucleate boiling in a saturated pool under various boiling conditions. The generated vapor concentrations in the bulk vapor layer were measured for the binary mixtures of water-ethanol and ethanol-acetone under various liquid concentrations, the heat fluxes and the liquid layer heights from the heated thin wires at the atmospheric pressure. The main experimental apparatus for measuring concentration of bulk vapor in the boiling and condensation system is shown. Two methods of measuring concentration, i.e., the dew point method and the laser absorption method were adopted. The dew point measurement was carried out by utilizing the copper heat transfer block installed in the central part of the vapor layer in the vessel. The commencement of the condensation was observed directly for determining the dew point by controlling its temperature. The laser light having wavelength of 3.39 micron meters was used for the laser light absorption method utilizing its absorptive property against ethanol vapor. The measured results by using both methods coincided well with each other. The measured concentrations of the bulk vapor for various superheatings of heated wires, the depth of liquid mixture layer and liquid concentrations were almost independent of those parameters and were almost in equilibrium with bulk liquid conditions even under the higher surface superheating and the lower liquid heights.

  3. Method and circuit for shaping laser output pulses

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P. (Inventor)

    1990-01-01

    The invention is a method and circuit for shaping laser pulses 17' in which a laser medium 12' in a laser resonator 10' that includes a Q-switch 14' and polarizer 13' which act in combination to control the loss of the resonator 10' and provide the laser output 17' representative of such loss. An optical diode 22' senses the level of the output pulse 17' and provides an output signal 23' that when amplified is used with a control voltage from a supply 29' provide a control signal 19' which is applied to Q-switch 14' to control the shape of the output pulse 17' by adjusting its length.

  4. Optimization Method for Solution Model of Laser Tracker Multilateration Measurement

    NASA Astrophysics Data System (ADS)

    Chen, Hongfang; Tan, Zhi; Shi, Zhaoyao; Song, Huixu; Yan, Hao

    2016-08-01

    Multilateration measurement using laser trackers suffers from a cumbersome solution method for high-precision measurements. Errors are induced by the self-calibration routines of the laser tracker software. This paper describes an optimization solution model for laser tracker multilateration measurement, which effectively inhibits the negative effect of this self-calibration, and further, analyzes the accuracy of the singular value decomposition for the described solution model. Experimental verification for the solution model based on laser tracker and coordinate measuring machine (CMM) was performed. The experiment results show that the described optimization model for laser tracker multilateration measurement has good accuracy control, and has potentially broad application in the field of laser tracker spatial localization.

  5. [Pilot results of prostatic adenoma treatment with diode laser Medilas D UroBeam in the Ukraine].

    PubMed

    Kogut, V V; Dzhuran, B V

    2012-01-01

    Pilot results of prostatic adenoma treatment with diode laser (940 nm) in 94 patients showed high efficacy of laser vaporization of the prostate. The effect was achieved in all the patients in minimal number of complications and in satisfactory tolerance of the surgery. Laser vaporization has some advantages over standard treatment (TUR) and is a method of choice in small and middle-size adenomas. In large adenoma good results were obtained in combination of laser vaporization with bipolar TUR.

  6. APPLICATION OF LASERS AND LASER-OPTICAL METHODS IN LIFE SCIENCES Low power cw-laser signatures on human skin

    NASA Astrophysics Data System (ADS)

    Lihachev, A.; Lesinsh, J.; Jakovels, D.; Spigulis, J.

    2011-01-01

    Impact of cw laser radiation on autofluorescence features of human skin is studied. Two methods of autofluorescence detection are applied: the spectral method with the use of a fibreoptic probe and spectrometer for determining the autofluorescence recovery kinetics at a fixed skin area of ~12 mm2, and the multispectral visualisation method with the use of a multispectral imaging camera for visualising long-term autofluorescence changes in a skin area of ~4 cm2. The autofluorescence recovery kinetics after preliminary laser irradiation is determined. Skin autofluorescence images with visible long-term changes — 'signatures' of low power laser treatment are acquired.

  7. 40 CFR Appendix A to Subpart Wwww... - Test Method for Determining Vapor Suppressant Effectiveness

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... organic HAP emission factor equations in Table 1 to this subpart require that the vapor suppressant... into the appropriate organic HAP emission factor equation. The vapor suppressant effectiveness factor... organic HAP emissions factor equations in Table 1 to this subpart to generate emission factors....

  8. 40 CFR Appendix A to Subpart Wwww... - Test Method for Determining Vapor Suppressant Effectiveness

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... organic HAP emission factor equations in Table 1 to this subpart require that the vapor suppressant... into the appropriate organic HAP emission factor equation. The vapor suppressant effectiveness factor... organic HAP emissions factor equations in Table 1 to this subpart to generate emission factors....

  9. 40 CFR Appendix A to Subpart Wwww... - Test Method for Determining Vapor Suppressant Effectiveness

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... organic HAP emission factor equations in Table 1 to this subpart require that the vapor suppressant... into the appropriate organic HAP emission factor equation. The vapor suppressant effectiveness factor... organic HAP emissions factor equations in Table 1 to this subpart to generate emission factors....

  10. Apparatus and method for removing mercury vapor from a gas stream

    DOEpatents

    Ganesan, Kumar

    2008-01-01

    A metallic filter effectively removes mercury vapor from gas streams. The filter captures the mercury which then can be released and collected as product. The metallic filter is a copper mesh sponge plated with a six micrometer thickness of gold. The filter removes up to 90% of mercury vapor from a mercury contaminated gas stream.

  11. Transverse-type laser assembly using induced electrical discharge excitation and method

    DOEpatents

    Ault, Earl R.

    1994-01-01

    A transverse-type laser assembly is disclosed herein. This assembly defines a laser cavity containing a vapor or gaseous substance which lases when subjected to specific electrical discharge excitation between a pair of spaced-apart electrodes located within the cavity in order to produce a source of light. An arrangement located entirely outside the laser cavity is provided for inducing a voltage across the electrodes within the cavity sufficient to provide the necessary electrical discharge excitation to cause a vapor substance between the electrodes to lase.

  12. Transverse-type laser assembly using induced electrical discharge excitation and method

    DOEpatents

    Ault, E.R.

    1994-04-19

    A transverse-type laser assembly is disclosed herein. This assembly defines a laser cavity containing a vapor or gaseous substance which lases when subjected to specific electrical discharge excitation between a pair of spaced-apart electrodes located within the cavity in order to produce a source of light. An arrangement located entirely outside the laser cavity is provided for inducing a voltage across the electrodes within the cavity sufficient to provide the necessary electrical discharge excitation to cause a vapor substance between the electrodes to lase. 3 figures.

  13. IR and UV laser-induced chemical vapor deposition: Chemical mechanism for a-Si:H and Cr (O,C) film formation

    NASA Astrophysics Data System (ADS)

    Hess, Peter

    The characteristic features of laser-induced chemical vapor deposition in the parallel and perpendicular laser beam/surface configurations are discussed. Low temperature chemical processing with directed and spatially localized energy deposition in the system is investigated. Results obtained for the deposition of hydrogenated amorphous silicon (a-Si:H) films in the parallel configuration employing CO 2 and KrFlasers and SiH 4 and Si 2H 6 as precursors are presented. As a second example, the growth of oxygen- and carbon-containing chromium films Cr(O,C) from chromium hexacarbonyl as the precursor using cw and pulse uv lasers is discussed. The chemical pathways leasing to film formation are investigated in detail.

  14. Apparatus and method for laser deposition of durable coatings

    DOEpatents

    Veligdan, James T.; Vanier, Peter; Barletta, Robert E.

    1995-08-15

    Method and apparatus for depositing durable coatings onto the surface of a substrate without heating the entire substrate to high temperatures by using lasers to heat the substrate and dissociate a deposition gas. The apparatus comprises a deposition chamber for enclosing the substrate upon which a coating is to be deposited, gas delivery means for directing a flow of deposition gas on the substrate, a first laser for heating the substrate, and a second laser for irradiating the deposition gas to dissociate the gas. The method includes placing a substrate within a vacuum deposition chamber and directing a flow of deposition gas on the substrate. Then the substrate is heated with a first laser while the deposition gas is irradiated with a second laser to dissociate the deposition gas.

  15. Apparatus and method for laser deposition of durable coatings

    DOEpatents

    Veligdan, J.T.; Vanier, P.; Barletta, R.E.

    1995-08-15

    Method and apparatus are disclosed for depositing durable coatings onto the surface of a substrate without heating the entire substrate to high temperatures by using lasers to heat the substrate and dissociate a deposition gas. The apparatus comprises a deposition chamber for enclosing the substrate upon which a coating is to be deposited, gas delivery means for directing a flow of deposition gas on the substrate, a first laser for heating the substrate, and a second laser for irradiating the deposition gas to dissociate the gas. The method includes placing a substrate within a vacuum deposition chamber and directing a flow of deposition gas on the substrate. Then the substrate is heated with a first laser while the deposition gas is irradiated with a second laser to dissociate the deposition gas. 1 fig.

  16. Native Fluorescence Detection Methods and Detectors for Naphthalene and/or Other Volatile Organic Compound Vapors

    NASA Technical Reports Server (NTRS)

    Hug, William F. (Inventor); Bhartia, Rohit (Inventor); Reid, Ray D. (Inventor); Lane, Arthur L. (Inventor)

    2014-01-01

    Naphthalene, benzene, toluene, xylene, and other volatile organic compounds have been identified as serious health hazards. This is especially true for personnel working with JP8 jet fuel and other fuels containing naphthalene as well as other hazardous volatile organic compounds (VOCs). Embodiments of the invention are directed to methods and apparatus for near-real-time in-situ detection and accumulated dose measurement of exposure to naphthalene vapor and other hazardous gaseous VOCs. The methods and apparatus employ excitation of fluorophors native or endogenous to compounds of interest using light sources emitting in the ultraviolet below 300 nm and measurement of native fluorescence emissions in distinct wavebands above the excitation wavelength. The apparatus of some embodiments are cell-phone-sized sensor/dosimeter "badges" to be worn by personnel potentially exposed to naphthalene or other hazardous VOCs. The badge sensor of some embodiments provides both real time detection and data logging of exposure to naphthalene or other VOCs of interest from which both instantaneous and accumulated dose can be determined. The badges employ a new native fluorescence based detection method to identify and differentiate VOCs. The particular focus of some embodiments are the detection and identification of naphthalene while other embodiments are directed to detection and identification of other VOCs like aromatic hydrocarbons such as benzene, toluene, and xylene.

  17. Apparatuses and methods for laser reading of thermoluminescent phosphors

    DOEpatents

    Braunlich, Peter F.; Tetzlaff, Wolfgang

    1989-01-01

    Apparatuses and methods for rapidly reading thermoluminescent phosphors to determine the amount of luminescent energy stored therein. The stored luminescent energy is interpreted as a measure of the total exposure of the thermoluminescent phosphor to ionizing radiation. The thermoluminescent phosphor reading apparatus uses a laser to generate a laser beam. The laser beam power level is monitored by a laser power detector and controlled to maintain the power level at a desired value or values which can vary with time. A shutter or other laser beam interrupting means is used to control exposure of the thermoluminescent phosphor to the laser beam. The laser beam can be equalized using an opitcal equalizer so that the laser beam has an approximately uniform power density across the beam. The heated thermoluminescent phosphor emits a visible or otherwise detectable luminescent emission which is measured as an indication of the radiation exposure of the thermoluminscent phosphors. Also disclosed are preferred signal processing and control circuits including one system using a digital computer. Also disclosed are time-profiled laser power cycles for pre-anneal, read and post-anneal treatment of phosphors.

  18. Antibacterial effects of allspice, garlic, and oregano essential oils in tomato films determined by overlay and vapor-phase methods.

    PubMed

    Du, W-X; Olsen, C W; Avena-Bustillos, R J; McHugh, T H; Levin, C E; Mandrell, R; Friedman, Mendel

    2009-09-01

    Physical properties as well as antimicrobial activities against Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes of allspice, garlic, and oregano essential oils (EOs) in tomato puree film-forming solutions (TPFFS) formulated into edible films at 0.5% to 3% (w/w) concentrations were investigated in this study. Antimicrobial activities were determined by 2 independent methods: overlay of the film on top of the bacteria and vapor-phase diffusion of the antimicrobial from the film to the bacteria. The results indicate that the antimicrobial activities against the 3 pathogens were in the following order: oregano oil > allspice oil > garlic oil. Listeria monocytogenes was less resistant to EO vapors, while E. coli O157:H7 was more resistant to EOs as determined by both overlay and vapor-phase diffusion tests. The presence of plant EO antimicrobials reduced the viscosity of TPFFS at the higher shear rates, but did not affect water vapor permeability of films. EOs increased elongation and darkened the color of films. The results of the present study show that the 3 plant-derived EOs can be used to prepare tomato-based antimicrobial edible films with good physical properties for food applications by both direct contact and indirectly by vapors emanating from the films.

  19. Methods for calculation of engineering parameters for gas separation. [vapor pressure and solubility of gases in organic liquids

    NASA Technical Reports Server (NTRS)

    Lawson, D. D.

    1979-01-01

    A group additivity method is generated which allows estimation, from the structural formulas alone, of the energy of vaporization and the molar volume at 25 C of many nonpolar organic liquids. Using these two parameters and appropriate thermodynamic relations, the vapor pressure of the liquid phase and the solubility of various gases in nonpolar organic liquids are predicted. It is also possible to use the data to evaluate organic and some inorganic liquids for use in gas separation stages or liquids as heat exchange fluids in prospective thermochemical cycles for hydrogen production.

  20. Development of More Cost-Effective Methods for Long-Term Monitoring of Soil Vapor Intrusion to Indoor Air Using Quantitative Passive Diffusive-Adsorptive Sampling Techniques

    DTIC Science & Technology

    2015-05-01

    ER-200830) Development of More Cost-Effective Methods for Long-Term Monitoring of Soil Vapor Intrusion to Indoor Air Using...Methods for Long-Term Monitoring of Soil Vapor Intrusion to Indoor Air Using Quantitative Passive Diffusive-Adsorptive Sampling Techniques W912HQ-08-C...volatile organic compounds (VOCs) at sites with potential human health risks. These risks were attributable to subsurface vapor intrusion to indoor air by

  1. The 532-nm 180-W (GreenLight®) laser vaporization of the prostate for the treatment of lower urinary tract symptoms: how durable is the new side-fire fiber with integrated cooling system?

    PubMed

    Brunken, Claus; Munsch, Maximilian; Tauber, Stephan; Schmidt, Rainer; Seitz, Christian

    2014-05-01

    The 532-nm side-fire laser vaporization is established for the treatment of symptomatic benign prostate hyperplasia. Meanwhile, the third generation of this system is offered by American Medical Systems, Inc. The laser power increased from 80 and 120 to 180 W from the first to the third generation. Despite good functional results, with the 80- and 120-W systems, the removal of prostate tissue is limited because of fiber degradation. To overcome this problem, the fiber was designed newly with an integrated cooling system and a sensor for decreasing the laser energy in case of overheating. We evaluate whether the new fiber still suffers from degradation with consecutive drop of power transmission during the procedure. The power output of the cooled fiber was measured in vitro and during prostate vaporization in ten patients. Laser beam power was measured at baseline and after the application each of 50 kJ during laser vaporization. Power emission of the fiber remains constant at 20, 80, and 180 W of power settings over the whole 40-kJ lifespan. During the transurethral procedure, a median total energy of 276 kJ (standard deviation 153 kJ) was applied for vaporization. Median power output from the fiber at the end of the procedure was 97% from the baseline value. There were no fiber malfunctions observed. In contrast to former generations, the third-generation laser fiber is durable without significant power loss during prostate vaporization.

  2. Theoretical studies of Resonance Enhanced Stimulated Raman Scattering (RESRS) of frequency doubled Alexandrite laser wavelength in cesium vapor

    NASA Technical Reports Server (NTRS)

    Lawandy, Nabil M.

    1987-01-01

    The third phase of research will focus on the propagation and energy extraction of the pump and SERS beams in a variety of configurations including oscillator structures. In order to address these questions a numerical code capable of allowing for saturation and full transverse beam evolution is required. The method proposed is based on a discretized propagation energy extraction model which uses a Kirchoff integral propagator coupled to the three level Raman model already developed. The model will have the resolution required by diffraction limits and will use the previous density matrix results in the adiabatic following limit. Owing to its large computational requirements, such a code must be implemented on a vector array processor. One code on the Cyber is being tested by using previously understood two-level laser models as guidelines for interpreting the results. Two tests were implemented: the evolution of modes in a passive resonator and the evolution of a stable state of the adiabatically eliminated laser equations. These results show mode shapes and diffraction losses for the first case and relaxation oscillations for the second one. Finally, in order to clarify the computing methodology used to exploit the speed of the Cyber's computational speed, the time it takes to perform both of the computations previously mentioned to run on the Cyber and VAX 730 must be measured. Also included is a short description of the current laser model (CAVITY.FOR) and a flow chart of the test computations.

  3. An Interpolation Method for Obtaining Thermodynamic Properties Near Saturated Liquid and Saturated Vapor Lines

    NASA Technical Reports Server (NTRS)

    Nguyen, Huy H.; Martin, Michael A.

    2003-01-01

    The availability and proper utilization of fluid properties is of fundamental importance in the process of mathematical modeling of propulsion systems. Real fluid properties provide the bridge between the realm of pure analytiis and empirical reality. The two most common approaches used to formulate thermodynamic properties of pure substances are fundamental (or characteristic) equations of state (Helmholtz and Gibbs functions) and a piecemeal approach that is described, for example, in Adebiyi and Russell (1992). This paper neither presents a different method to formulate thermodynamic properties of pure substances nor validates the aforementioned approaches. Rather its purpose is to present a method to be used to facilitate the accurate interpretation of fluid thermodynamic property data generated by existing property packages. There are two parts to this paper. The first part of the paper shows how efficient and usable property tables were generated, with the minimum number of data points, using an aerospace industry standard property package (based on fundamental equations of state approach). The second part describes an innovative interpolation technique that has been developed to properly obtain thermodynamic properties near the saturated liquid and saturated vapor lines.

  4. A method to improve the utilization of GNSS observation for water vapor tomography

    NASA Astrophysics Data System (ADS)

    Yao, Y. B.; Zhao, Q. Z.; Zhang, B.

    2016-01-01

    Existing water vapor tomographic methods use Global Navigation Satellite System (GNSS) signals penetrating the entire research area while they do not consider signals passing through its sides. This leads to the decreasing use of observed satellite signals and allows for no signals crossing from the bottom or edge areas especially for those voxels in research areas of interest. Consequently, the accuracy of the tomographic results for the bottom of a research area, and the overall reconstructed accuracy do not reach their full potential. To solve this issue, an approach which uses GPS data with both signals that pass the side and top of a research area is proposed. The advantages of proposed approach include improving the utilization of existing GNSS observations and increasing the number of voxels crossed by satellite signals. One point should be noted that the proposed approach needs the support of radiosonde data inside the tomographic region. A tomographic experiment was implemented using observed GPS data from the Continuously Operating Reference System (CORS) Network of Zhejiang Province, China. The comparison of tomographic results with data from a radiosonde shows that the root mean square error (RMS), bias, mean absolute error (MAE), and standard deviation (SD) of the proposed approach are superior to those of the traditional method.

  5. Water-assisted growth of graphene on carbon nanotubes by the chemical vapor deposition method.

    PubMed

    Feng, Jian-Min; Dai, Ye-Jing

    2013-05-21

    Combining carbon nanotubes (CNTs) with graphene has been proved to be a feasible method for improving the performance of graphene for some practical applications. This paper reports a water-assisted route to grow graphene on CNTs from ferrocene and thiophene dissolved in ethanol by the chemical vapor deposition method in an argon flow. A double injection technique was used to separately inject ethanol solution and water for the preparation of graphene/CNTs. First, CNTs were prepared from ethanol solution and water. The injection of ethanol solution was suspended and water alone was injected into the reactor to etch the CNTs. Thereafter, ethanol solution was injected along with water, which is the key factor in obtaining graphene/CNTs. Transmission electron microscopy, scanning electron microscopy, X-ray diffraction, and Raman scattering analyses confirmed that the products were the hybrid materials of graphene/CNTs. X-ray photo-electron spectroscopy analysis showed the presence of oxygen rich functional groups on the surface of the graphene/CNTs. Given the activity of the graphene/CNT surface, CdS quantum dots adhered onto it uniformly through simple mechanical mixing.

  6. Method of defining features on materials with a femtosecond laser

    DOEpatents

    Roos, Edward Victor; Roeske, Franklin; Lee, Ronald S.; Benterou, Jerry J.

    2006-05-23

    The invention relates to a pulsed laser ablation method of metals and/or dielectric films from the surface of a wafer, printed circuit board or a hybrid substrate. By utilizing a high-energy ultra-short pulses of laser light, such a method can be used to manufacture electronic circuits and/or electro-mechanical assemblies without affecting the material adjacent to the ablation zone.

  7. Efficient method for transport simulations in quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Maczka, Mariusz; Pawlowski, Stanislaw

    2016-12-01

    An efficient method for simulating quantum transport in quantum cascade lasers is presented. The calculations are performed within a simple approximation inspired by Büttiker probes and based on a finite model for semiconductor superlattices. The formalism of non-equilibrium Green's functions is applied to determine the selected transport parameters in a typical structure of a terahertz laser. Results were compared with those obtained for a infinite model as well as other methods described in literature.

  8. NUVEM - New methods to Use gnss water Vapor Estimates for Meteorology of Portugal

    NASA Astrophysics Data System (ADS)

    Fernandes, R. M. S.; Viterbo, P.; Bos, M. S.; Martins, J. P.; Sá, A. G.; Valentim, H.; Jones, J.

    2014-12-01

    NUVEM (New methods to Use gnss water Vapor Estimates for Meteorology of Portugal) is a collaborative project funded by the Portuguese National Science Foundation (FCT) aiming to implement a multi-disciplinary approach in order to operationalize the inclusion of GNSS-PWV estimates for nowcasting in Portugal, namely for the preparation of warnings of severe weather. To achieve such goal, the NUVEM project is divided in two major components: a) Development and implementation of methods to compute accurate estimates of PWV (Precipitable Water Vapor) in NRT (Near Real-Time); b) Integration of such estimates in nowcasting procedures in use at IPMA (Portuguese Meteorological Service). Methodologies will be optimized at SEGAL to passive and actively access to the data; the PWV estimations will be computed using PPP (Precise Point Positioning), which permits the estimation of each individual station separately; solutions will be validated using internal and external values; and computed solutions will be transferred timely to the IPMA Operational Center. Validation of derived estimations using robust statistics is an important component of the project. The need for sending computed values as soon as possible to IPMA requires fast but reliable internal (e.g., noise estimation) and external (e.g., feedback from IPMA using other sensors like radiosondes) assessment of the quality of the PWV estimates. At IPMA, the goal is to implement the operational use of GNSS-PWV to assist weather nowcasting in Portugal. This will be done with the assistance of the Meteo group of IDL. Maps of GNSS-PWV will be automatically created and compared with solutions provided by other operational systems in order to help IPMA to detect suspicious patterns at near real time. This will be the first step towards the assimilation of GNSS-PWV estimates at IPMA nowcasting models. The NUVEM (EXPL/GEO-MET/0413/2013) project will also contribute to the active participation of Portugal at the COST Action ES

  9. Laser pulse stretcher method and apparatus

    DOEpatents

    Hawkins, Jon K.; Williams, William A.

    1990-01-01

    The output of an oscillator stage of a laser system is monitored by a photocell which is coupled to a feedback section to control a Pockels Cell and change the light output of the oscillator stage. A synchronizing pulse is generated in timed relation to the initiation of operation of the oscillator stage and is applied to a forward feed section which cooperates with the feedback section to maintain the light output constant for an extended time interval.

  10. Self-seeded single-frequency laser peening method

    DOEpatents

    Dane, C. Brent; Hackel, Lloyd; Harris, Fritz B.

    2009-08-11

    A method of operating a laser to obtain an output pulse having a single wavelength, comprises inducing an intracavity loss into a laser resonator having an amount that prevents oscillation during a time that energy from the pump source is being stored in the gain medium. Gain is built up in the gain medium with energy from the pump source until formation of a single-frequency relaxation oscillation pulse in the resonator. Upon detection of the onset of the relaxation oscillation pulse, the intracavity loss is reduced, such as by Q-switching, so that the built-up gain stored in the gain medium is output from the resonator in the form of an output pulse at a single frequency. An electronically controllable output coupler is controlled to affect output pulse characteristics. The laser acts a master oscillator in a master oscillator power amplifier configuration. The laser is used for laser peening.

  11. Self-seeded single-frequency laser peening method

    DOEpatents

    DAne, C Brent; Hackey, Lloyd A; Harris, Fritz B

    2012-06-26

    A method of operating a laser to obtain an output pulse having a single wavelength, comprises inducing an intracavity loss into a laser resonator having an amount that prevents oscillation during a time that energy from the pump source is being stored in the gain medium. Gain is built up in the gain medium with energy from the pump source until formation of a single-frequency relaxation oscillation pulse in the resonator. Upon detection of the onset of the relaxation oscillation pulse, the intracavity loss is reduced, such as by Q-switching, so that the built-up gain stored in the gain medium is output from the resonator in the form of an output pulse at a single frequency. An electronically controllable output coupler is controlled to affect output pulse characteristics. The laser acts a master oscillator in a master oscillator power amplifier configuration. The laser is used for laser peening.

  12. Team resource management participant's handbook for the atomic vapor laser isotope separation program

    SciTech Connect

    Bennett, Tom

    1998-05-01

    The goal of any operation is to complete tasks efficiently and effectively. Working safely is completely consistent with efficient, reliable operations. Working in an unsafe manner is not effective or ultimately efficient. If someone is hurt, work stops. Following the steps advocated by Team Resource Management (TRM) leads to more safe, efficient, effective work habits. TRM is a method used by teams (i.e., leaders and workers) to conduct technical business. It is used by the aviation industry to improve reliability and safety through formalizing the way it does business. High reliability organizations do exist. They conduct thousands of high-consequence operations a year, essentially error-free. Naval air carriers, air traffic control, and commercial aviation are some of these kinds of organizations. How did they get that way? What kinds of people staff them? Can we become a high reliability organization? This workshop will look at these questions. When we are done, it will be up to you to determine if we have the right stuff. The goals of this workshop are to: Describe Team Resource Management and its purpose; Describe Performance Shaping Factors (PSFs) and their role in predicting and managing team performance and errors; Describe the principles for managing human error; Describe TRM's 12 rules-of-thumb (the "Dirty Dozen") and use of safety nets; Conduct Operational Risk Management (ORM); Demonstrate ways to keep TRM working.

  13. High-power Ti:sapphire laser at 820 nm for scanning ground-based water-vapor differential absorption lidar.

    PubMed

    Wagner, Gerd; Behrendt, Andreas; Wulfmeyer, Volker; Späth, Florian; Schiller, Max

    2013-04-10

    The Ti:sapphire (TISA) laser transmitter of the mobile, three-dimensional-scanning water-vapor differential absorption lidar (DIAL) of the University of Hohenheim is described in detail. The dynamically-stable, unidirectional ring resonator contains a single Brewster-cut TISA crystal, which is pumped from both sides with 250 Hz using a diode-pumped frequency-doubled Nd:YAG laser. The resonator is injection seeded and actively frequency-stabilized using a phase-sensitive technique. The TISA laser is operating near 820 nm, which is optimum for ground-based water-vapor DIAL measurements. An average output power of up to 6.75 W with a beam quality factor of M2<2 is reached. The pointing stability is <13 μrad (rms), the depolarization <1%. The overall optical-optical conversion efficiency is up to 19%. The pulse length is 40 ns with a pulse linewidth of <157 MHz. The short- and long-term frequency stabilities are 10 MHz (rms). A spectral purity of 99.9% was determined by pointing to a stratus cloud in low-elevation scanning mode with a cloud bottom height of ≈2.4 km.

  14. Selection of the optimal combination of water vapor absorption lines for detection of temperature in combustion zones of mixing supersonic gas flows by diode laser absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Mironenko, V. R.; Kuritsyn, Yu. A.; Bolshov, M. A.; Liger, V. V.

    2016-12-01

    Determination of a gas medium temperature by diode laser absorption spectrometry (DLAS) is based on the measurement of integral intensities of the absorption lines of a test molecule (generally water vapor molecule). In case of local thermodynamic equilibrium temperature is inferred from the ratio of the integral intensities of two lines with different low energy levels. For the total gas pressure above 1 atm the absorption lines are broadened and one cannot find isolated well resolved water vapor absorption lines within relatively narrow spectral interval of fast diode laser (DL) tuning range (about 3 cm-1). For diagnostics of a gas object in the case of high temperature and pressure DLAS technique can be realized with two diode lasers working in different spectral regions with strong absorption lines. In such situation the criteria of the optimal line selection differs significantly from the case of narrow lines. These criteria are discussed in our work. The software for selection the optimal spectral regions using the HITRAN-2012 and HITEMP data bases is developed. The program selects spectral regions of DL tuning, minimizing the error of temperature determination δT/T, basing on the attainable experimental error of line intensity measurement δS. Two combinations of optimal spectral regions were selected - (1.392 & 1.343 μm) and (1.392 & 1.339 μm). Different algorithms of experimental data processing are discussed.

  15. Enhancing vapor generation at a liquid-solid interface using micro/nanoscale surface structures fabricated by femtosecond laser surface processing

    NASA Astrophysics Data System (ADS)

    Anderson, Troy P.; Wilson, Chris; Zuhlke, Craig A.; Kruse, Corey; Gogos, George; Ndao, Sidy; Alexander, Dennis

    2015-03-01

    Femtosecond Laser Surface Processing (FLSP) is a versatile technique for the fabrication of a wide variety of micro/nanostructured surfaces with tailored physical and chemical properties. Through control over processing conditions such as laser fluence, incident pulse count, polarization, and incident angle, the size and density of both micrometer and nanometer-scale surface features can be tailored. Furthermore, the composition and pressure of the environment both during and after laser processing have a substantial impact on the final surface chemistry of the target material. FLSP is therefore a powerful tool for optimizing interfacial phenomena such as wetting, wicking, and phasetransitions associated with a vapor/liquid/solid interface. In the present study, we utilize a series of multiscale FLSPgenerated surfaces to improve the efficiency of vapor generation on a structured surface. Specifically, we demonstrate that FLSP of stainless steel 316 electrode surfaces in an alkaline electrolysis cell results in increased efficiency of the water-splitting reaction used to generate hydrogen. The electrodes are fabricated to be superhydrophilic (the contact angle of a water droplet on the surface is less than 5 degrees). The overpotential of the hydrogen evolution reaction (HER) is measured using a 3-electrode configuration with a structured electrode as the working electrode. The enhancement is attributed to several factors including increased surface area, increased wettability, and the impact of micro/nanostructures on the bubble formation and release. Special emphasis is placed on identifying and isolating the relative impacts of the various contributions.

  16. Reappraisal of disparities between osmolality estimates by freezing point depression and vapor pressure deficit methods.

    PubMed

    Winzor, Donald J

    2004-02-15

    As a response to recent expression of concern about possible unreliability of vapor pressure deficit measurements (K. Kiyosawa, Biophys. Chem. 104 (2003) 171-188), the results of published studies on the temperature dependence of the osmotic pressure of aqueous polyethylene glycol solutions are shown to account for the observed discrepancies between osmolality estimates obtained by freezing point depression and vapor pressure deficit osmometry--the cause of the concern.

  17. Fast Fiber-Laser Alignment: Beam Spot-Size Method

    NASA Astrophysics Data System (ADS)

    Zhang, Rong; Guo, Jingyan; Shi, Frank G.

    2005-03-01

    A novel fast and cost-effective method is introduced for the active alignment of a fiber to a laser diode: only four easy laser beam spot-size measurements are required for moving the fiber tip from the far field to the proximity of the optimal alignment position, thus dramatically reducing the total alignment time (at least five times faster than a conventional method),as experimentally confirmed. Moreover, in contrast to the existing methods,the new method is failure-proof. The principle of the proposed method can be applied generally to any type of packages and is illustrated by an example of a butterfly package.

  18. Comparison of Adsorbed Mercury Screening Method With Cold-Vapor Atomic Absorption Spectrophotometry for Determination of Mercury in Soil

    NASA Technical Reports Server (NTRS)

    Easterling, Donald F.; Hovanitz, Edward S.; Street, Kenneth W.

    2000-01-01

    A field screening method for the determination of elemental mercury in environmental soil samples involves the thermal desorption of the mercury from the sample onto gold and then the thermal desorption from the gold to a gold-film mercury vapor analyzer. This field screening method contains a large number of conditions that could be optimized for the various types of soils encountered. In this study, the conditions were optimized for the determination of mercury in silty clay materials, and the results were comparable to the cold-vapor atomic absorption spectrophotometric method of determination. This paper discusses the benefits and disadvantages of employing the field screening method and provides the sequence of conditions that must be optimized to employ this method of determination on other soil types.

  19. The fabrication of vertically aligned and periodically distributed carbon nanotube bundles and periodically porous carbon nanotube films through a combination of laser interference ablation and metal-catalyzed chemical vapor deposition.

    PubMed

    Yuan, Dajun; Lin, Wei; Guo, Rui; Wong, C P; Das, Suman

    2012-06-01

    Scalable fabrication of carbon nanotube (CNT) bundles is essential to future advances in several applications. Here, we report on the development of a simple, two-step method for fabricating vertically aligned and periodically distributed CNT bundles and periodically porous CNT films at the sub-micron scale. The method involves laser interference ablation (LIA) of an iron film followed by CNT growth via iron-catalyzed chemical vapor deposition. CNT bundles with square widths ranging from 0.5 to 1.5 µm in width, and 50-200 µm in length, are grown atop the patterned catalyst over areas spanning 8 cm(2). The CNT bundles exhibit a high degree of control over square width, orientation, uniformity, and periodicity. This simple scalable method of producing well-placed and oriented CNT bundles demonstrates a high application potential for wafer-scale integration of CNT structures into various device applications, including IC interconnects, field emitters, sensors, batteries, and optoelectronics, etc.

  20. Self-assembly of Arg-Phe nanostructures via the solid-vapor phase method.

    PubMed

    Liberato, Michelle S; Kogikoski, Sergio; Silva, Emerson R; Coutinho-Neto, Mauricio D; Scott, Luis P B; Silva, Ricardo H; Oliveira, Vani X; Ando, Rômulo A; Alves, Wendel A

    2013-01-24

    We report for the first time on the self-assembly of nanostructures composed exclusively of alternating positively charged and hydrophobic amino acids. A novel arginine/phenylalanine octapeptide, RF8, was synthesized. Because the low hydrophobicity of this sequence makes its spontaneous ordering through solution-based methods difficult, a recently proposed solid-vapor approach was used to obtain nanometric architectures on ITO/PET substrates. The formation of the nanostructures was investigated under different preparation conditions, specifically, under different gas-phase solvents (aniline, water, and dichloromethane), different peptide concentrations in the precursor solution, and different incubation times. The stability of the assemblies was experimentally studied by electron microscopy and thermogravimetric analysis coupled with mass spectrometry. The secondary structure was assessed by infrared and Raman spectroscopy, and the arrays were found to assume an antiparallel β-sheet conformation. FEG-SEM images clearly reveal the appearance of fibrillar structures that form extensive homogeneously distributed networks. A close relationship between the morphology and preparation parameters was found, and a concentration-triggered mechanism was suggested. Molecular dynamics simulations were performed to address the thermal stability and nature of intermolecular interactions of the putative assembly structure. Results obtained when water is considered as solvent shows that a stable lamellar structure is formed containing a thin layer of water in between the RF8 peptides that is stabilized by H-bonding.

  1. Long-term evaluation of the controlled pressure method for assessment of the vapor intrusion pathway.

    PubMed

    Holton, Chase; Guo, Yuanming; Luo, Hong; Dahlen, Paul; Gorder, Kyle; Dettenmaier, Erik; Johnson, Paul C

    2015-02-17

    Vapor intrusion (VI) investigations often require sampling of indoor air for evaluating occupant risks, but can be confounded by temporal variability and the presence of indoor sources. Controlled pressure methods (CPM) have been proposed as an alternative, but temporal variability of CPM results and whether they are indicative of impacts under natural conditions have not been rigorously investigated. This study is the first involving a long-term CPM test at a house having a multiyear high temporal resolution indoor air data set under natural conditions. Key observations include (a) CPM results exhibited low temporal variability, (b) false-negative results were not obtained, (c) the indoor air concentrations were similar to the maximum concentrations under natural conditions, and (d) results exceeded long-term average concentrations and emission rates under natural conditions by 1-2 orders of magnitude. Thus, the CPM results were a reliable indicator of VI occurrence and worst-case exposure regardless of day or time of year of the CPM test.

  2. A novel method for furfural recovery via gas stripping assisted vapor permeation by a polydimethylsiloxane membrane

    PubMed Central

    Hu, Song; Guan, Yu; Cai, Di; Li, Shufeng; Qin, Peiyong; Karim, M. Nazmul; Tan, Tianwei

    2015-01-01

    Furfural is an important platform chemical with a wide range of applications. However, due to the low concentration of furfural in the hydrolysate, the conventional methods for furfural recovery are energy-intensive and environmentally unfriendly. Considering the disadvantages of pervaporation (PV) and distillation in furfural separation, a novel energy-efficient ‘green technique’, gas stripping assisted vapor permeation (GSVP), was introduced in this work. In this process, the polydimethylsiloxane (PDMS) membrane was prepared by employing water as solvent. Coking in pipe and membrane fouling was virtually non-existent in this new process. In addition, GSVP was found to achieve the highest pervaporation separation index of 216200 (permeate concentration of 71.1 wt% and furfural flux of 4.09 kgm−2h−1) so far, which was approximately 2.5 times higher than that found in pervaporation at 95°C for recovering 6.0 wt% furfural from water. Moreover, the evaporation energy required for GSVP decreased by 35% to 44% relative to that of PV process. Finally, GSVP also displayed more promising potential in industrial application than PV, especially when coupled with the hydrolysis process or fermentation in biorefinery industry. PMID:25819091

  3. A novel method for furfural recovery via gas stripping assisted vapor permeation by a polydimethylsiloxane membrane.

    PubMed

    Hu, Song; Guan, Yu; Cai, Di; Li, Shufeng; Qin, Peiyong; Karim, M Nazmul; Tan, Tianwei

    2015-03-30

    Furfural is an important platform chemical with a wide range of applications. However, due to the low concentration of furfural in the hydrolysate, the conventional methods for furfural recovery are energy-intensive and environmentally unfriendly. Considering the disadvantages of pervaporation (PV) and distillation in furfural separation, a novel energy-efficient 'green technique', gas stripping assisted vapor permeation (GSVP), was introduced in this work. In this process, the polydimethylsiloxane (PDMS) membrane was prepared by employing water as solvent. Coking in pipe and membrane fouling was virtually non-existent in this new process. In addition, GSVP was found to achieve the highest pervaporation separation index of 216200 (permeate concentration of 71.1 wt% and furfural flux of 4.09 kg m(-2) h(-1)) so far, which was approximately 2.5 times higher than that found in pervaporation at 95°C for recovering 6.0 wt% furfural from water. Moreover, the evaporation energy required for GSVP decreased by 35% to 44% relative to that of PV process. Finally, GSVP also displayed more promising potential in industrial application than PV, especially when coupled with the hydrolysis process or fermentation in biorefinery industry.

  4. A novel method for furfural recovery via gas stripping assisted vapor permeation by a polydimethylsiloxane membrane

    NASA Astrophysics Data System (ADS)

    Hu, Song; Guan, Yu; Cai, Di; Li, Shufeng; Qin, Peiyong; Karim, M. Nazmul; Tan, Tianwei

    2015-03-01

    Furfural is an important platform chemical with a wide range of applications. However, due to the low concentration of furfural in the hydrolysate, the conventional methods for furfural recovery are energy-intensive and environmentally unfriendly. Considering the disadvantages of pervaporation (PV) and distillation in furfural separation, a novel energy-efficient `green technique', gas stripping assisted vapor permeation (GSVP), was introduced in this work. In this process, the polydimethylsiloxane (PDMS) membrane was prepared by employing water as solvent. Coking in pipe and membrane fouling was virtually non-existent in this new process. In addition, GSVP was found to achieve the highest pervaporation separation index of 216200 (permeate concentration of 71.1 wt% and furfural flux of 4.09 kgm-2h-1) so far, which was approximately 2.5 times higher than that found in pervaporation at 95°C for recovering 6.0 wt% furfural from water. Moreover, the evaporation energy required for GSVP decreased by 35% to 44% relative to that of PV process. Finally, GSVP also displayed more promising potential in industrial application than PV, especially when coupled with the hydrolysis process or fermentation in biorefinery industry.

  5. A novel pre-oxidation method for elemental mercury removal utilizing a complex vaporized absorbent.

    PubMed

    Zhao, Yi; Hao, Runlong; Guo, Qing

    2014-09-15

    A novel semi-dry integrative method for elemental mercury (Hg(0)) removal has been proposed in this paper, in which Hg(0) was initially pre-oxidized by a vaporized liquid-phase complex absorbent (LCA) composed of a Fenton reagent, peracetic acid (CH3COOOH) and sodium chloride (NaCl), after which Hg(2+) was absorbed by the resultant Ca(OH)2. The experimental results indicated that CH3COOOH and NaCl were the best additives for Hg(0) oxidation. Among the influencing factors, the pH of the LCA and the adding rate of the LCA significantly affected the Hg(0) removal. The coexisting gases, SO2 and NO, were characterized as either increasing or inhibiting in the removal process, depending on their concentrations. Under optimal reaction conditions, the efficiency for the single removal of Hg(0) was 91%. Under identical conditions, the efficiencies of the simultaneous removal of SO2, NO and Hg(0) were 100%, 79.5% and 80.4%, respectively. Finally, the reaction mechanism for the simultaneous removal of SO2, NO and Hg(0) was proposed based on the characteristics of the removal products as determined by X-ray diffraction (XRD), atomic fluorescence spectrometry (AFS), the analysis of the electrode potentials, and through data from related research references.

  6. Fabrication of efficient planar perovskite solar cells using a one-step chemical vapor deposition method

    PubMed Central

    Tavakoli, Mohammad Mahdi; Gu, Leilei; Gao, Yuan; Reckmeier, Claas; He, Jin; Rogach, Andrey L.; Yao, Yan; Fan, Zhiyong

    2015-01-01

    Organometallic trihalide perovskites are promising materials for photovoltaic applications, which have demonstrated a rapid rise in photovoltaic performance in a short period of time. We report a facile one-step method to fabricate planar heterojunction perovskite solar cells by chemical vapor deposition (CVD), with a solar power conversion efficiency of up to 11.1%. We performed a systematic optimization of CVD parameters such as temperature and growth time to obtain high quality films of CH3NH3PbI3 and CH3NH3PbI3-xClx perovskite. Scanning electron microscopy and time resolved photoluminescence data showed that the perovskite films have a large grain size of more than 1 micrometer, and carrier life-times of 10 ns and 120 ns for CH3NH3PbI3 and CH3NH3PbI3-xClx, respectively. This is the first demonstration of a highly efficient perovskite solar cell using one step CVD and there is likely room for significant improvement of device efficiency. PMID:26392200

  7. Vapor pressure of three brominated flame retardants determined by using the Knudsen effusion method.

    PubMed

    Fu, Jinxia; Suuberg, Eric M

    2012-03-01

    Brominated flame retardants (BFRs) have been used in a variety of consumer products in the past four decades. The vapor pressures for three widely used BFRs, that is, tetrabromobisphenol A (TBBPA), hexabromocyclododecane (HBCD), and octabromodiphenyl ethers (octaBDEs) mixtures, were determined using the Knudsen effusion method and compared with those of decabromodiphenyl ether (BDE209). The values measured extrapolated to 298.15 K are 8.47 × 10⁻⁹, 7.47 × 10⁻¹⁰, and 2.33 × 10⁻⁹  Pa, respectively. The enthalpies of sublimation for these BFRs were estimated using the Clausius-Clapeyron equation and are 143.6 ± 0.4, 153.7 ± 3.1, and 150.8 ± 3.2 kJ/mole, respectively. In addition, the enthalpies of fusion and melting temperatures for these BFRs were also measured in the present study.

  8. Purification and Crystal Growth of Lead Iodide by Physical Vapor Transport Method

    NASA Technical Reports Server (NTRS)

    Wright, G. W.; Cole, M.; Chen, Y.-F.; Chen, K.-T.; Chen, H.; Chattopadhyay, K.; Burger, A.

    1998-01-01

    Lead iodide (PbI2) is a layered compound semiconductor being developed as room temperature x- and gamma-ray detector. Compared to the more studied material, mercuric iodide, PbI2 has a higher melting temperature and no phase transition until liquid phase which are indications of better mechanical properties. In this study, the source material was purified by the zone-refining process, and the purest section was extracted from center of the the zone-refined ingot to be grown by physical vapor transport (PVT) method. The zone-refined material and as-grown crystals were characterized by optical microscopy and differential scanning calorimetry (DSC) to reveal the surface morphology, purity and stoichiometry. The results shows that both materials are near-stoichiometric composition, with the purity of the as-grown crystals higher than zone-refined materials. The resistivity of the as-grown crystal (10" Omega-cm) was derived from current-voltage (I-V) measurement, and is 10 times higher than the zone-refined materials. Detail results will be presented and discussed.

  9. Heterodyne laser spectroscopy system

    DOEpatents

    Wyeth, Richard W.; Paisner, Jeffrey A.; Story, Thomas

    1989-01-01

    A heterodyne laser spectroscopy system utilizes laser heterodyne techniques for purposes of laser isotope separation spectroscopy, vapor diagnostics, processing of precise laser frequency offsets from a reference frequency and the like, and provides spectral analysis of a laser beam.

  10. Heterodyne laser spectroscopy system

    DOEpatents

    Wyeth, Richard W.; Paisner, Jeffrey A.; Story, Thomas

    1990-01-01

    A heterodyne laser spectroscopy system utilizes laser heterodyne techniques for purposes of laser isotope separation spectroscopy, vapor diagnostics, processing of precise laser frequency offsets from a reference frequency, and provides spectral analysis of a laser beam.

  11. Laser And Nonlinear Optical Materials For Laser Remote Sensing

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.

    2005-01-01

    NASA remote sensing missions involving laser systems and their economic impact are outlined. Potential remote sensing missions include: green house gasses, tropospheric winds, ozone, water vapor, and ice cap thickness. Systems to perform these measurements use lanthanide series lasers and nonlinear devices including second harmonic generators and parametric oscillators. Demands these missions place on the laser and nonlinear optical materials are discussed from a materials point of view. Methods of designing new laser and nonlinear optical materials to meet these demands are presented.

  12. Insights in the laser-induced breakdown spectroscopy signal generation underwater using dual pulse excitation — Part I: Vapor bubble, shockwaves and plasma

    NASA Astrophysics Data System (ADS)

    Lazic, V.; Laserna, J. J.; Jovicevic, S.

    2013-04-01

    Plasma and vapor bubble formation and evolution after a nanosecond laser pulse delivered to aluminum targets inside water were studied by fast photography. This technique was also applied to monitor the plasma produced by a second laser pulse and for different interpulse delays. The bubble growth was evident only after 3 μs from the first laser pulse and the bubble shape changed during expansion and collapse cycles. The evolution and propagation of the initial shockwave and its reflections both from the back sample surface and cell walls were detected by Schlieren photography. The primary plasma develops in two phases: violent particle expulsion and ionization during the first μs, followed by slow plasma growth from the ablation crater into the evolving vapor bubble. The shape of the secondary plasma strongly depends on the inner bubble pressure whereas the particle expulsion into the expanded bubble is much less evident. Both the primary and secondary plasma have similar duration of about 30 μs. Detection efficiency of the secondary plasma is much reduced by light refraction at the curved bubble-water interface, which behaves as a negative lens; this leads to an apparent reduction of the plasma dimensions. Defocusing power of the bubble lens increases with its expansion due to the lowering of the vapor's refraction index with respect to that of the surrounding liquid (Lazic et al., 2012 [1]). Smell's reflections of secondary plasma radiation at the expanded bubble wall redistribute the detected intensity on a wavelength-dependent way and allow gathering of the emission also from the external plasma layer that otherwise, would not enter into the optical system.

  13. A Laser Sheet Self-Calibration Method for Scanning PIV

    NASA Astrophysics Data System (ADS)

    Knutsen, Anna N.; Dawson, James R.; Lawson, John M.; Worth, Nicholas A.

    2016-11-01

    A laser sheet self-calibration method for scanning PIV has been developed to replace the current laser sheet calibration, which is complex, time consuming and very sensitive to misalignment of the optics or cameras during experiments. The new calibration method is simpler, faster and crucially more robust. The concept behind the method is to traverse a laser sheet through the measurement volume, take a series of images from two different views, and calculate the global 3D particle locations. This information is used to find the real space coordinates of the measurement volume and the orientation and width of the laser sheets. The spatial location of the particles is found by object matching and triangulation. The light intensity in the laser sheet has an approximately Gaussian shape, and the illumination of one particle which will be illuminated multiple times during the scan will thus vary as the sheet is scanned across the measurement volume. The thickness of the laser sheet is calculated by identifying the variation of illumination of the particles during a scan and fitting this to a Gaussian shaped curve, while the orientation is found using a least square fit. The accuracy of the new method will be presented with respect to both synthetic and experimental data.

  14. Method and apparatus for laser scribing glass sheet substrate coatings

    SciTech Connect

    Borgeson, Frank A.; Hanak, Joseph J.; Harju, Ricky S.; Helman, Norman L.; Hecht, Kenneth R.

    2003-05-06

    A method and apparatus (42) for laser scribing coatings on glass sheet substrates by conveying the substrate adjacent a laser source (83) that provides a pulsed laser beam (84) with a wavelength at a near-infrared fundamental frequency and having a frequency in the range of 50 to 100 kilohertz and a pulse duration in the range of 8 to 70 nanoseconds, and by reflecting the beam by an XYZ galvanometer controlled mirror system (90) toward an uncoated surface of the substrate for passage therethrough to the coating on the other surface to provide overlapping ablations through the coating and scribing at a speed of at least 1000 millimeters per second.

  15. Method and apparatus for laser scribing glass sheet substrate coatings

    SciTech Connect

    Borgeson, Frank A.; Hanak, Joseph J.; Harju, Ricky S.; Harju, Karen M.; Helman, Norman L.; Hecht, Kenneth R.

    2005-07-19

    A method and apparatus (42) for laser scribing coatings on glass sheet substrates by conveying the substrate adjacent a laser source (83) that provides a pulsed laser beam (84) with a wavelength at a near-infrared fundamental frequency and having a frequency in the range of 50 to 100 kilohertz and a pulse duration in the range of 8 to 70 nanoseconds, and by reflecting the beam by an XYZ galvanometer controlled mirror system (90) toward an uncoated surface of the substrate for passage therethrough to the coating on the other surface to provide overlapping ablations through the coating and scribing at a speed of at least 1000 millimeters per second.

  16. Method for laser welding ultra-thin metal foils

    DOEpatents

    Pernicka, J.C.; Benson, D.K.; Tracy, C.E.

    1996-03-26

    A method for simultaneously cutting and welding ultra-thin foils having a thickness of less than 0.002 inches wherein two ultra-thin films are stacked and clamped together. A pulsed laser such as of the Neodymium: YAG type is provided and the beam of the laser is directed onto the stacked films to cut a channel through the films. The laser is moved relative to the stacked foils to cut the stacked foils at successive locations and to form a plurality of connected weld beads to form a continuous weld. 5 figs.

  17. Method for laser welding ultra-thin metal foils

    DOEpatents

    Pernicka, John C.; Benson, David K.; Tracy, C. Edwin

    1996-01-01

    A method for simultaneously cutting and welding ultra-thin foils having a thickness of less than 0.002 inches wherein two ultra-thin films are stacked and clamped together. A pulsed laser such as of the Neodymium: YAG type is provided and the beam of the laser is directed onto the stacked films to cut a channel through the films. The laser is moved relative to the stacked foils to cut the stacked foils at successive locations and to form a plurality of connected weld beads to form a continuous weld.

  18. Tungsten-carbon multilayers for x-ray optics prepared by ArF excimer-laser-induced chemical vapor deposition

    SciTech Connect

    Mutoh, K.; Yamada, Y.; Iwabuchi, T.; Miyata, T. )

    1990-08-01

    The authors have studied the characteristics of tungsten (W) and carbon (C) thin films, and W/C multilayers prepared by ArF excimer-laser-induced chemical vapor deposition using tungsten hexafluoride and benzene gases. Amorphous W and C films with very smooth surfaces were obtained at substrate temperatures of 100--200 {degree}C and 100--300 {degree}C, respectively. In small-angle x-ray scattering measurements for the multilayers deposited at 200 {degree}C, a first order of multilayer reflections were clearly observed. Furthermore, Auger electron spectroscopy showed that W and C layers in the multilayers were periodically deposited.

  19. Tungsten-carbon multilayers for x-ray optics prepared by ArF excimer-laser-induced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Mutoh, Katsuhiko; Yamada, Yuka; Iwabuchi, Takashi; Miyata, Takeo

    1990-08-01

    The authors have studied the characteristics of tungsten (W) and carbon (C) thin films, and W/C multilayers prepared by ArF excimer-laser-induced chemical vapor deposition using tungsten hexafluoride and benzene gases. Amorphous W and C films with very smooth surfaces were obtained at substrate temperatures of 100-200 °C and 100-300 °C, respectively. In small-angle x-ray scattering measurements for the multilayers deposited at 200 °C, a first order of multilayer reflections were clearly observed. Furthermore, Auger electron spectroscopy showed that W and C layers in the multilayers were periodically deposited.

  20. Fabrication of photonic crystal structures by tertiary-butyl arsine-based metal-organic vapor-phase epitaxy for photonic crystal lasers

    NASA Astrophysics Data System (ADS)

    Yoshida, Masahiro; Kawasaki, Masato; De Zoysa, Menaka; Ishizaki, Kenji; Hatsuda, Ranko; Noda, Susumu

    2016-06-01

    The fabrication of air/semiconductor two-dimensional photonic crystal structures by air-hole-retained crystal regrowth using tertiary-butyl arsine-based metal-organic vapor-phase epitaxy for GaAs-based photonic crystal lasers is investigated. Photonic crystal air holes with filling factors of 10-13%, depths of ˜280 nm, and widths of 120-150 nm are successfully embedded. The embedded air holes exhibit characteristic shapes due to the anisotropy of crystal growth. Furthermore, a low lasing threshold of ˜0.5 kA/cm2 is achieved with the fabricated structures.

  1. The application of 120-W high-performance system GreenLight laser vaporization of the prostate in high-risk patients.

    PubMed

    Tao, Wei; Xue, BoXin; Zang, Yachen; Sun, ChuanYang; Yang, Dongrong; Zhang, Yuanyuan; Shan, YuXi

    2013-07-01

    The purpose of this study is to evaluate the safety and efficacy of 120-W potassium titanyl phosphate (KTP) laser vaporization in patients with benign prostatic hyperplasia (BPH) who also had cardiopulmonary diseases who were taking long-term anticoagulants and were at high risk of bleeding complications. The prospective study included 188 patients with severe lower urinary tract symptoms who underwent 120-W KTP laser vaporization of the prostate. All patients were at high cardiopulmonary risk, having presented with an American Society of Anesthesiology score of 3 or greater. Of those, 45 patients were taking oral anticoagulants, and 1 had a severe bleeding disorder. BPH was successfully treated with 120-W KTP laser vaporization in all patients. Mean preoperative prostate volume ± SD was 66 ± 23.1 ml, and mean operative time was 50.8 ± 15.5 min. There were no major complications intraoperatively or postoperatively, and no blood transfusions were required. Postoperatively, only 14 patients (7.4 %) required bladder irrigation. Average catheterization time was 1.9 ± 1.5 days (range, 1-5 days). Three patients required reoperation due to enlarged prostates from residual adenoma. At 3-, 6,- 12-, and 24-month follow-ups, mean urinary peak flow increased from 8.0 ± 3.6 ml/s to 19.1 ± 5.6, 19.2 ± 4.7, 19.1 ± 4.65, and 19.2 ± 4.34 ml/s, respectively. Mean International Prostate Symptom Scores decreased over time, from 25.6 ± 5.1 (3 months) to 9.4 ± 2.8, 7.05 ± 1.46, 6.24 ± 1.36, and 6.20 ± 1.32 (24 months), respectively. 120-W HPS KTP laser vaporization is a safe and effective treatment option in BPH patients at high risk and those on anticoagulation therapy who have severe LUTS secondary to BPH.

  2. Method and device for controlling plume during laser welding

    DOEpatents

    Fuerschbach, Phillip W.; Jellison, James L.; Keicher, David M.; Oberkampf, William L.

    1991-01-01

    A method and apparatus for enhancing the weldment of a laser welding system is provided. The laser weld plume control device includes a cylindrical body defining an upside-down cone cavity; the upper surface of the body circumscribes the base of the cone cavity, and the vertex of the cone cavity forms an orifice concentrically located with respect to the laser beam and the plume which forms as a result of the welding operation. According to the method of the invention, gas is directed radially inward through inlets in the upper surface of the body into and through channels in the wall of the body and finally through the orifice of the body, and downward onto the surface of the weldment. The gas flow is then converted by the orifice of the device from radial flow to an axisymmetric gas jet flowing away from the weldment surface in a direction perpendicular to the surface and opposite to that of the laser.

  3. Plasmakinetic enucleation of prostate versus 160-W laser photoselective vaporization for the treatment of benign prostatic hyperplasia

    PubMed Central

    Wang, Si-Jun; Mu, Xiao-Nan; Chen, Ji; Jin, Xun-Bo; Zhang, Shi-Bao; Zhang, Long-Yang

    2017-01-01

    To evaluate the safety and efficacy of plasmakinetic enucleation of the prostate (PKEP) for the treatment of symptomatic benign prostatic hyperplasia (BPH) compared with 160-W lithium triboride laser photoselective vaporization of the prostate (PVP). From February 2011 to July 2012, a prospective nonrandomized study was performed. One-hundred one patients underwent PKEP, and 110 underwent PVP. No severe intraoperative complications were recorded, and none of the patients in either group required a blood transfusion. Shorter catheterization time (38.14 ± 23.64 h vs 72.54 ± 28.38 h, P < 0.001) and hospitalization (2.32 ± 1.25 days vs 4.07 ± 1.23 days, P < 0.001) were recorded in the PVP group. At 12-month postoperatively, the PKEP group had a maintained and statistically improvement in International Prostate Symptom Score (IPSS) (4.07 ± 2.07 vs 5.00 ± 2.10; P < 0.001), quality of life (QoL) (1.08 ± 0.72 vs 1.35 ± 0.72; P = 0.007), maximal urinary flow rate (Qmax) (24.75 ± 5.87 ml s−1 vs 22.03 ± 5.04 ml s−1; P < 0.001), postvoid residual urine volume (PVR) (14.29 ± 6.97 ml vs 17.00 ± 6.11 ml; P = 0.001), and prostate-specific antigen (PSA) value (0.78 ± 0.57 ng ml−1 vs 1.27 ± 1.07 ng ml−1; P < 0.001). Both PKEP and PVP relieve low urinary tract symptoms (LUTS) due to BPH with low complication rates. PKEP can completely remove prostatic adenoma while the total amount of tissue removed by PVP is less than that can be removed by PKEP. Based on our study of the follow-up, PKEP provides better postoperative outcomes than PVP. PMID:26732101

  4. FAR-INFRARED SPECTROSCOPY OF CATIONIC POLYCYCLIC AROMATIC HYDROCARBONS: ZERO KINETIC ENERGY PHOTOELECTRON SPECTROSCOPY OF PENTACENE VAPORIZED FROM LASER DESORPTION

    SciTech Connect

    Zhang Jie; Han Fangyuan; Pei Linsen; Kong Wei; Li Aigen

    2010-05-20

    The distinctive set of infrared (IR) emission bands at 3.3, 6.2, 7.7, 8.6, and 11.3 {mu}m are ubiquitously seen in a wide variety of astrophysical environments. They are generally attributed to polycyclic aromatic hydrocarbon (PAH) molecules. However, not a single PAH species has yet been identified in space, as the mid-IR vibrational bands are mostly representative of functional groups and thus do not allow one to fingerprint individual PAH molecules. In contrast, the far-IR (FIR) bands are sensitive to the skeletal characteristics of a molecule, hence they are important for chemical identification of unknown species. With an aim to offer laboratory astrophysical data for the Herschel Space Observatory, Stratospheric Observatory for Infrared Astronomy, and similar future space missions, in this work we report neutral and cation FIR spectroscopy of pentacene (C{sub 22}H{sub 14}), a five-ring PAH molecule. We report three IR active modes of cationic pentacene at 53.3, 84.8, and 266 {mu}m that may be detectable by space missions such as the SAFARI instrument on board SPICA. In the experiment, pentacene is vaporized from a laser desorption source and cooled by a supersonic argon beam. We have obtained results from two-color resonantly enhanced multiphoton ionization and two-color zero kinetic energy photoelectron (ZEKE) spectroscopy. Several skeletal vibrational modes of the first electronically excited state of the neutral species and those of the cation are assigned, with the aid of ab initio and density functional calculations. Although ZEKE is governed by the Franck-Condon principle different from direct IR absorption or emission, vibronic coupling in the long ribbon-like molecule results in the observation of a few IR active modes. Within the experimental resolution of {approx}7 cm{sup -1}, the frequency values from our calculation agree with the experiment for the cation, but differ for the electronically excited intermediate state. Consequently, modeling of the

  5. Transfer of spin angular momentum from Cs vapor to nearby Cs salts through laser-induced spin currents

    SciTech Connect

    Ishikawa, K.; Patton, B.; Olsen, B. A.; Jau, Y.-Y.; Happer, W.

    2011-06-15

    Optical pumping of alkali-metal atoms in vapor cells causes spin currents to flow to the cell walls where excess angular momentum accumulates in the wall nuclei. Experiments reported here indicate that the substantial enhancement of the nuclear-spin polarization of salts at the cell walls is primarily due to the nuclear-spin current, with a lesser contribution from the electron-spin current of the vapor.

  6. Laser-Induced Fluorescence Measurements of Translational Temperature and Relative Cycle Number by use of Optically Pumped Trace-Sodium Vapor

    NASA Astrophysics Data System (ADS)

    Dobson, Chris C.

    1999-06-01

    Sodium fluorescence induced by a narrow-bandwidth tunable laser has been used to measure temperature, pressure, axial velocity, and species concentrations in wind tunnels, rocket engine exhausts, and the upper atmosphere. Optical pumping of the ground states of the sodium, however, can radically alter the shape of the laser-induced fluorescence excitation spectrum, complicating such measurements. Here a straightforward extension of rate equations originally proposed to account for the features of the pumped spectrum is used to make temperature measurements from spectra taken in pumped vapor. Also determined from the spectrum is the relative fluorescence cycle number, which has application to measurement of diffusion rate and transverse flow velocity. The accuracy of both the temperature and the cycle-number measurements is comparable with that of temperature measurements made in the absence of pumping.

  7. Laser-Induced Fluorescence Measurements of Translational Temperature and Relative Cycle Number by use of Optically Pumped Trace-Sodium Vapor

    NASA Technical Reports Server (NTRS)

    Dobson, Chris C.

    1998-01-01

    Sodium fluorescence induced by a narrow bandwidth tunable laser has been used to measure temperature, pressure, axial velocity and species concentrations in wind tunnels, rocket engine exhausts and the upper atmosphere. Optical pumping of the ground states of the sodium, however, can radically alter the shape of the laser induced fluorescence excitation spectrum, complicating such measurements. Here a straightforward extension of rate equations originally proposed to account for the features of the pumped spectrum is to make temperature measurements from spectra taken in pumped vapor. Also determined from the spectrum is the relative fluorescence cycle number, which has application to measurement of diffusion rate and transverse flow velocity. The accuracy of both the temperature and cycle-number measurements is comparable with that of temperature measurements made in the absence of pumping.

  8. Laser-Induced Fluorescence Measurements of Translational Temperature and Relative Cycle Number by use of Optically Pumped Trace-Sodium Vapor

    NASA Technical Reports Server (NTRS)

    Dobson, Chris C.

    1999-01-01

    Sodium fluorescence induced by a narrow-bandwidth tunable laser has been used to measure temperature, pressure, axial velocity, and species concentrations in wind tunnels, rocket engine exhausts, and the upper atmosphere. Optical pumping of the ground states of the sodium, however, can radically alter the shape of the laser-induced fluorescence excitation spectrum, complicating such measurements. Here a straightforward extension of rate equations originally proposed to account for the features of the pumped spectrum is used to make temperature measurements from spectra taken in pumped vapor. Also determined from the spectrum is the relative fluorescence cycle number, which has application to measurement of diffusion rate and transverse flow velocity, The accuracy of both the temperature and the cycle-number measurements is comparable with that of temperature measurements made in the absence of pumping.

  9. Laser-induced fluorescence measurements of translational temperature and relative cycle number by use of optically pumped trace-sodium vapor.

    PubMed

    Dobson, C C

    1999-06-20

    Sodium fluorescence induced by a narrow-bandwidth tunable laser has been used to measure temperature, pressure, axial velocity, and species concentrations in wind tunnels, rocket engine exhausts, and the upper atmosphere. Optical pumping of the ground states of the sodium, however, can radically alter the shape of the laser-induced fluorescence excitation spectrum, complicating such measurements. Here a straightforward extension of rate equations originally proposed to account for the features of the pumped spectrum is used to make temperature measurements from spectra taken in pumped vapor. Also determined from the spectrum is the relative fluorescence cycle number, which has application to measurement of diffusion rate and transverse flow velocity. The accuracy of both the temperature and the cycle-number measurements is comparable with that of temperature measurements made in the absence of pumping.

  10. Experimental and theoretical study of the performance of optically pumped cesium vapor laser as a function of the pump-to-laser beam overlap

    NASA Astrophysics Data System (ADS)

    Barmashenko, Boris D.; Cohen, Tom; Lebiush, Eyal; Auslender, Ilya; Rosenwaks, Salman

    2016-10-01

    We report on the results of an experimental study of Ti:Sapphire pumped Cs laser and theoretical modeling of these results, where we focused on the influence of the pump-to-laser beam overlap, a crucial parameter for optimizing the output laser power. Non monotonic dependence of the laser power (optimized over the temperature) on the pump beam radius was observed with a maximum achieved at the ratio 0.7 between the pump and laser beam radii. The optimal temperature decreased with increasing pump beam radius. Maximum laser power > 370 mW with an optical-to-optical efficiency of 43% and slope efficiency 55% was obtained. A simple optical model of the laser, where Gaussian spatial shapes of the pump and laser intensities in any cross section of the beams were assumed, was compared to the experiments. Good agreement was obtained between the measured and calculated dependence of the laser power on the pump power at different pump beam radii and also of the laser power, threshold pump power and optimal temperature on the pump beam radius. The model does not use empirical parameters such as mode overlap efficiency but rather the pump and laser beam spatial shapes as input parameters. The present results combined with results of the application of the model to K DPAL and Ti:Sapphire pumped Cs laser, indicate that the model can describe the operation of different optically pumped alkali lasers with arbitrary spatial distributions of the pump and laser beam widths.

  11. Comparison of Columnar Water Vapor Measurements During The Fall 1997 ARM Intensive Observation Period: Solar Transmittance Methods

    NASA Technical Reports Server (NTRS)

    Schmid, B.; Michalsky, J. J.; Slater, D. W.; Barnard, J. C.; Halthore, R. N.; Liljegren, J. C.; Holben, B. N.; Eck, T. F.; Livingston, J. M.; Russell, P. B.

    2000-01-01

    In the fall of 1997, during an Intensive Observation Period (IOP), the Atmospheric Radiation Measurement (ARM) program conducted a study of water vapor abundance measurement at its Southern Great Plains (SGP) site. Among a large number of instruments, four sun-tracking radiometers were present to measure the columnar water vapor (CWV). All four solar radiometers retrieve CWV by measuring total solar transmittance in the 0.94-gm water vapor absorption band and subtracting contributions due to Rayleigh, ozone and aerosol transmittances. The aerosol optical depth comparisons among the same four radiometers has been presented elsewhere (Geophys. Res. Lett., 26, 17, 2725-2728, 1999). We have used three different methods to retrieve CWV. In a first round of comparison no attempt was made to standardize on the same radiative transfer model and its underlying water vapor spectroscopy. In the second round of comparison we used the same line-by-line code (which includes recently corrected H2O spectroscopy) to retrieve CAN from all four suntracking radiometers. This decreased the mean CWV by 8% or 13%. The spread of 8% in the solar radiometer results found when using the same model is an indication of the other-than-model uncertainties involved in determining CWV from solar transmittance measurements with current instrumentation.

  12. Bacteriological comparison of low anal fistula operated by ordinary methods and laser methods

    NASA Astrophysics Data System (ADS)

    Yang, Yuanrong; Xiong, Yigai

    1996-09-01

    Since 1989, 42 cases with low anal fistula were operated with laser and ordinary methods respectively. During the operation, secreted or charred tissues were extracted from the surface of the wound for bacteria culture. Experimental group (laser method): no bacteria were found in 24 cases operated by laser method. Control group (ordinary method): bacterial were found in 16 out of 18 cases operated by ordinary methods. The results of two different group showed that they had statistical difference for P < 0.001. So, CO2 laser is proved to be a definitely practical tool in surgical use for its bacteria killing power. While the anal fistula were operated by the laser, the neurotic carboatomic tissue can block blood vessel and prevent infection from spreading. The high temperature produced by the carboatomic action have enough ability to kill directly the bacteria living in the anal fistula.

  13. Apparatus, system, and method for laser-induced breakdown spectroscopy

    SciTech Connect

    Effenberger, Jr., Andrew J; Scott, Jill R; McJunkin, Timothy R

    2014-11-18

    In laser-induced breakdown spectroscopy (LIBS), an apparatus includes a pulsed laser configured to generate a pulsed laser signal toward a sample, a constructive interference object and an optical element, each located in a path of light from the sample. The constructive interference object is configured to generate constructive interference patterns of the light. The optical element is configured to disperse the light. A LIBS system includes a first and a second optical element, and a data acquisition module. The data acquisition module is configured to determine an isotope measurement based, at least in part, on light received by an image sensor from the first and second optical elements. A method for performing LIBS includes generating a pulsed laser on a sample to generate light from a plasma, generating constructive interference patterns of the light, and dispersing the light into a plurality of wavelengths.

  14. Method for laser welding a fin and a tube

    DOEpatents

    Fuerschbach, Phillip W.; Mahoney, A. Roderick; Milewski, John O

    2001-01-01

    A method of laser welding a planar metal surface to a cylindrical metal surface is provided, first placing a planar metal surface into approximate contact with a cylindrical metal surface to form a juncture area to be welded, the planar metal surface and cylindrical metal surface thereby forming an acute angle of contact. A laser beam, produced, for example, by a Nd:YAG pulsed laser, is focused through the acute angle of contact at the juncture area to be welded, with the laser beam heating the juncture area to a welding temperature to cause welding to occur between the planar metal surface and the cylindrical metal surface. Both the planar metal surface and cylindrical metal surface are made from a reflective metal, including copper, copper alloys, stainless steel alloys, aluminum, and aluminum alloys.

  15. Equivalent common path method in large-scale laser comparator

    NASA Astrophysics Data System (ADS)

    He, Mingzhao; Li, Jianshuang; Miao, Dongjing

    2015-02-01

    Large-scale laser comparator is main standard device that providing accurate, reliable and traceable measurements for high precision large-scale line and 3D measurement instruments. It mainly composed of guide rail, motion control system, environmental parameters monitoring system and displacement measurement system. In the laser comparator, the main error sources are temperature distribution, straightness of guide rail and pitch and yaw of measuring carriage. To minimize the measurement uncertainty, an equivalent common optical path scheme is proposed and implemented. Three laser interferometers are adjusted to parallel with the guide rail. The displacement in an arbitrary virtual optical path is calculated using three displacements without the knowledge of carriage orientations at start and end positions. The orientation of air floating carriage is calculated with displacements of three optical path and position of three retroreflectors which are precisely measured by Laser Tracker. A 4th laser interferometer is used in the virtual optical path as reference to verify this compensation method. This paper analyzes the effect of rail straightness on the displacement measurement. The proposed method, through experimental verification, can improve the measurement uncertainty of large-scale laser comparator.

  16. Speckle reduction methods in laser-based picture projectors

    NASA Astrophysics Data System (ADS)

    Akram, M. Nadeem; Chen, Xuyuan

    2016-02-01

    Laser sources have been promised for many years to be better light sources as compared to traditional lamps or light-emitting diodes (LEDs) for projectors, which enable projectors having wide colour gamut for vivid image, super brightness and high contrast for the best picture quality, long lifetime for maintain free operation, mercury free, and low power consumption for green environment. A major technology obstacle in using lasers for projection has been the speckle noise caused by to the coherent nature of the lasers. For speckle reduction, current state of the art solutions apply moving parts with large physical space demand. Solutions beyond the state of the art need to be developed such as integrated optical components, hybrid MOEMS devices, and active phase modulators for compact speckle reduction. In this article, major methods reported in the literature for the speckle reduction in laser projectors are presented and explained. With the advancement in semiconductor lasers with largely reduced cost for the red, green and the blue primary colours, and the developed methods for their speckle reduction, it is hoped that the lasers will be widely utilized in different projector applications in the near future.

  17. Environmental site description for a Uranium Atomic Vapor Laser Isotope Separation (U-AVLIS) production plant at the Paducah Gaseous Diffusion Plant site

    SciTech Connect

    Marmer, G.J.; Dunn, C.P.; Moeller, K.L.; Pfingston, J.M.; Policastro, A.J.; Yuen, C.R.; Cleland, J.H.

    1991-09-01

    Uranium enrichment in the United States has utilized a diffusion process to preferentially enrich the U-235 isotope in the uranium product. The U-AVLIS process is based on electrostatic extraction of photoionized U-235 atoms from an atomic vapor stream created by electron-beam vaporization of uranium metal alloy. The U-235 atoms are ionized when precisely tuned laser light -- of appropriate power, spectral, and temporal characteristics -- illuminates the uranium vapor and selectively photoionizes the U-235 isotope. A programmatic document for use in screening DOE site to locate a U-AVLIS production plant was developed and implemented in two parts. The first part consisted of a series of screening analyses, based on exclusionary and other criteria, that identified a reasonable number of candidate sites. These sites were subjected to a more rigorous and detailed comparative analysis for the purpose of developing a short list of reasonable alternative sites for later environmental examination. This environmental site description (ESD) provides a detailed description of the PGDP site and vicinity suitable for use in an environmental impact statement (EIS). The report is based on existing literature, data collected at the site, and information collected by Argonne National Laboratory (ANL) staff during a site visit. 65 refs., 15 tabs.

  18. High-speed growth of YBa2Cu3O7 - δ film with high critical temperature on MgO single crystal substrate by laser chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Zhao, Pei; Ito, Akihiko; Tu, Rong; Goto, Takashi

    2010-12-01

    a-axis- and c-axis-oriented YBa2Cu3O7 - δ films were prepared on a (100) MgO single crystal substrate by chemical vapor deposition enhanced by a continuous wave Nd:YAG laser. A c-axis-oriented YBCO film with a critical temperature of 89 K was prepared at a high deposition rate of 57 µm h - 1, about 2-600 times higher than that of conventional chemical vapor deposition.

  19. A new pulsed laser deposition technique: Scanning multi-component pulsed laser deposition method

    SciTech Connect

    Fischer, D.; Jansen, M.; Fuente, G. F. de la

    2012-04-15

    The scanning multi-component pulsed laser deposition (PLD) method realizes uniform depositions of desired coatings by a modified pulsed laser deposition process, preferably with a femto-second laser-system. Multi-component coatings (single or multilayered) are thus deposited onto substrates via laser induced ablation of segmented targets. This is achieved via horizontal line-scanning of a focused laser beam over a uniformly moving target's surface. This process allows to deposit the desired composition of the coating simultaneously, starting from the different segments of the target and adjusting the scan line as a function of target geometry. The sequence and thickness of multilayers can easily be adjusted by target architecture and motion, enabling inter/intra layer concentration gradients and thus functional gradient coatings. This new, simple PLD method enables the achievement of uniform, large-area coatings. Case studies were performed with segmented targets containing aluminum, titanium, and niobium. Under the laser irradiation conditions applied, all three metals were uniformly ablated. The elemental composition within the rough coatings obtained was fixed by the scanned area to Ti-Al-Nb = 1:1:1. Crystalline aluminum, titanium, and niobium were found to coexist side by side at room temperature within the substrate, without alloy formation up to 600 deg. C.

  20. A new pulsed laser deposition technique: scanning multi-component pulsed laser deposition method.

    PubMed

    Fischer, D; de la Fuente, G F; Jansen, M

    2012-04-01

    The scanning multi-component pulsed laser deposition (PLD) method realizes uniform depositions of desired coatings by a modified pulsed laser deposition process, preferably with a femto-second laser-system. Multi-component coatings (single or multilayered) are thus deposited onto substrates via laser induced ablation of segmented targets. This is achieved via horizontal line-scanning of a focused laser beam over a uniformly moving target's surface. This process allows to deposit the desired composition of the coating simultaneously, starting from the different segments of the target and adjusting the scan line as a function of target geometry. The sequence and thickness of multilayers can easily be adjusted by target architecture and motion, enabling inter/intra layer concentration gradients and thus functional gradient coatings. This new, simple PLD method enables the achievement of uniform, large-area coatings. Case studies were performed with segmented targets containing aluminum, titanium, and niobium. Under the laser irradiation conditions applied, all three metals were uniformly ablated. The elemental composition within the rough coatings obtained was fixed by the scanned area to Ti-Al-Nb = 1:1:1. Crystalline aluminum, titanium, and niobium were found to coexist side by side at room temperature within the substrate, without alloy formation up to 600 °C.