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Sample records for dioxide laser radiation

  1. 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.

  2. Interaction of carbon dioxide laser radiation with a nanotube array in the presence of a constant electric field

    SciTech Connect

    Sadykov, N. R.; Scorkin, N. A.

    2012-06-15

    The dependence of the current density on the leading edge width of the alternating (high-frequency) field amplitude is studied at various constant (or unsteady) fields. The dependence of amplified microwaves in the two-millimeter range on a longitudinal coordinate is determined. The problem of submillimeter radiation generation in a system of parallel carbon nanotubes exposed to two-frequency carbon dioxide (CO{sub 2} laser) laser radiation in the presence of a constant (or unsteady) field is studied. The possibility of using freely oriented carbon nanotubes parallel to each other is shown.

  3. Laser surgery: using the carbon dioxide laser.

    PubMed Central

    Wright, V. C.

    1982-01-01

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

  4. 21 CFR 179.43 - Carbon dioxide laser for etching food.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Carbon dioxide laser for etching food. 179.43... FOOD Radiation and Radiation Sources § 179.43 Carbon dioxide laser for etching food. Carbon dioxide... conditions: (a) The radiation source consists of a carbon dioxide laser designed to emit pulsed infrared...

  5. 21 CFR 179.43 - Carbon dioxide laser for etching food.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Carbon dioxide laser for etching food. 179.43... § 179.43 Carbon dioxide laser for etching food. Carbon dioxide laser light may be safely used for... consists of a carbon dioxide laser designed to emit pulsed infrared radiation with a wavelength of 10.6...

  6. Tunable pulsed carbon dioxide laser

    NASA Technical Reports Server (NTRS)

    Megie, G. J.; Menzies, R. T.

    1981-01-01

    Transverse electrically-excited-atmosphere (TEA) laser is continuously tunable over several hundred megahertz about centers of spectral lines of carbon dioxide. It is operated in single longitudinal mode (SLM) by injection of beam from continuous-wave, tunable-waveguide carbon dioxide laser, which serves as master frequency-control oscillator. Device measures absorption line of ozone; with adjustments, it is applicable to monitoring of atmospheric trace species.

  7. Comparative bactericidal exposures for selected oral bacteria using carbon dioxide laser radiation

    SciTech Connect

    Dederich, D.N.; Pickard, M.A.; Vaughn, A.S.; Tulip, J.; Zakariasen, K.L. )

    1990-01-01

    Although relatively high CO{sub 2} laser energies have been shown to sterilize root canals, the response of several bacterial strains to decreasing exposures of CO{sub 2} laser energy remains unknown. Freshly grown bacterial cells were irradiated on glass microscope coverslips. A comparison of equivalent energy exposures with differing parameters was made on the bacterial viability. No statistically significant difference was found in the energy required to kill closely related bacterial species. However, the energy density required to kill greater than 99.5% of the bacteria is less than 200 J/cm{sup 2}, much less than that shown to sterilize in a previous study.

  8. [Effects of carbon dioxide laser radiation on bone tissue: macroscopic study on rats].

    PubMed

    Niccoli-Filho, W; Sampaio, T A; Guimarães-Filho, R

    2001-01-01

    The use of CO2 laser in osseous tissue to execute osteotomies is still questionable, mainly due to the increase of temperature in the site of irradiation. The purpose of this research was to carry out a pilot study in order to analyze macroscopically the effect of CO2 laser irradiation on rat tibia and to establish security parameters regarding power. Twelve rats were submitted to irradiation with 1, 3 and 5 watts of power and were examined immediately, 3, 7 and 14 days after irradiation. The results showed better healing when irradiation was carried out with the power of 1 watt; the 3- and 5-watt powers caused delay in the chronology of healing.

  9. Carbon dioxide slab laser

    SciTech Connect

    Tulip, J.

    1988-01-12

    A gas slab laser is described comprising: first and second elongated electrodes each including a planar light reflecting surface disposed so as to form a light guide only in a plane perpendicular to the planar surface and to define a gas discharge gap therebetween; a laser gas disposed in the gap; and means for applying a radio frequency current between the first and second electrodes to establish a laser-exciting discharge in the laser gas.

  10. Gamma radiation characteristics of plutonium dioxide fuel

    NASA Technical Reports Server (NTRS)

    Gingo, P. J.

    1969-01-01

    Investigation of plutonium dioxide as an isotopic fuel for Radioisotope Thermoelectric Generators yielded the isotopic composition of production-grade plutonium dioxide fuel, sources of gamma radiation produced by plutonium isotopes, and the gamma flux at the surface.

  11. Formation of periodic surface ripples under the action of pulsed carbon dioxide laser radiation on fused silica

    NASA Astrophysics Data System (ADS)

    Emel'Ianov, V. I.; Konov, V. I.; Tokarev, V. N.; Seminogov, V. N.

    1989-01-01

    Theoretical and experimental results on the formation of periodic surface ripples (PSR) on fused silica under the normal-incidence pulsed linearly-polarized light of a wavelength-tunable CO2 laser are reported. The dielectric permittivity of silica under conditions of PSR formation has been determined for the first time. Good agreement between theoretical and experimental results is achieved only if the complete theory of PSR is applied, taking into account electrodynamic and thermal processes along with growth rate calculations for capillary waves.

  12. Formation of micron and submicron structures on a zirconium oxide surface exposed to nanosecond laser radiation

    SciTech Connect

    Ganin, D V; Mikolutskiy, S I; Khomich, V Yu; Yamshchikov, V A; Tokarev, V N; Shmakov, V A

    2014-04-28

    Possibility of forming quasi-periodic structures of micron and submicron dimensions on a surface of zirconium dioxide under the action of eximer ArF laser radiation is shown experimentally and theoretically. (interaction of laser radiation with matter)

  13. Heat pump processes induced by laser radiation

    NASA Technical Reports Server (NTRS)

    Garbuny, M.; Henningsen, T.

    1980-01-01

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

  14. Prevention of Enamel Adjacent to Bracket Demineralization Following Carbon Dioxide Laser Radiation and Titanium Tetra Fluoride Solution Treatment: An In Vitro Study

    PubMed Central

    Mirhashemi, Amir Hossein; Hakimi, Sina; Ahmad Akhoundi, Mohammad Sadegh; Chiniforush, Nasim

    2016-01-01

    Introduction: The aim of this study was to assess the caries-preventive potential of carbon dioxide (CO2) laser application in conjunction with the use of titanium tetra fluoride solution on the enamel adjacent to bracket. Methods: Seventy-five freshly extracted bovine incisors were used. In order to attach the brackets, the area of examination was covered with adhesive tape to limit acid etching of the entire enamel surface. Metal orthodontic brackets for upper central were bonded to all the teeth following the manufacturer’s instruction. Then all the teeth were painted with 2 layers of acid-resistant nail varnish on all surfaces except the boxes area cervical to the brackets. The teeth were then randomly divided into five groups (n = 15): control group (C); laser group (L); titanium group (T); laser-titanium group (LT) and titanium-laser group (TL). The laser-titanium group was first irradiated with CO2 laser (same as the L group) then TiF4 solution was applied on the enamel (same as the T group). Samples in the TL group were first treated with TiF4 solution (same as the T group) and then irradiated with CO2 laser on the surface (same as the L group). Then, the teeth were immersed in pH-cycling solutions. After that, the amount of calcium released into the two solutions (de- and re-mineralization) was measured with an atomic absorption spectroscopy. The data were analyzed by one-way Analysis of var-iance (ANOVA) and Tukey test. Results: Calcium loss in LT, TL and T groups were significantly lower than those in the L and C groups (P < 0.05). Conclusion: The application of Titanium tetra fluoride 4% solution on enamel can inhibit as much as 87% of subsequent caries like lesion progression. PMID:28144441

  15. Carbon dioxide laser management cervical intraepithelial neoplasia

    SciTech Connect

    Bellina, J.H.; Wright, V.C.; Voros, J.I.; Riopelle, M.A.; Hohenschutz, V.

    1981-12-01

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

  16. Pulsed-discharge carbon dioxide lasers

    NASA Technical Reports Server (NTRS)

    Willetts, David V.

    1990-01-01

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

  17. Solar pumped continuous wave carbon dioxide laser

    NASA Technical Reports Server (NTRS)

    Yesil, O.; Christiansen, W. H.

    1978-01-01

    In an effort to demonstrate the feasibility of a solar pumped laser concept, gain has been measured in a CO2-He laser medium optically pumped by blackbody radiation. Various gas mixtures of CO2 and He have been pumped by blackbody radiation emitted from an electrically heated oven. Using a CO2 laser as a probe, an optical gain coefficient of 1.8 x 10 to the -3rd/cm has been measured at 10.6 microns for a 9:1 CO2-He mixture at an oven temperature of about 1500 K, a gas temperature of about 400 K and a pressure of about 1 torr. This corresponds to a small signal gain coefficient when allowance is made for saturation effects due to the probe beam, in reasonable agreement with a theoretical value.

  18. a Blackbody-Pumped Carbon Dioxide Laser

    NASA Astrophysics Data System (ADS)

    Insuik, Robin Joy

    A proof of concept experiment has been carried out to demonstrate the feasibility of using blackbody radiation to pump a gas laser. Building on earlier experiments in which optical gain was measured in a CO(,2) laser mixture exposed to blackbody radiation at a temperature of 1500(DEGREES)K, continuous wave oscillation of CO(,2) has been achieved, for the first time, using radiation from a blackbody cavity as the pump source. This was made possible by actively cooling the laser mixture as it was exposed to the radiation field of an electrically heated oven. Output power measurements are presented from a series of experiments using mixtures of CO(,2), He, and Ar. Maximum output power was obtained with a 20%CO(,2) - 15%He- 65%Ar mixture at pressures around 6-10 Torr. The output power was found to vary greatly with the gas temperature and the blackbody temperature. By varying these parameters output powers up to 8 mW have been achieved. The effects of the buffer gas are also shown to be important. Based on the experimental results, it is believed that the buffer gas is needed to inhibit diffusion of the excited species out of the laser mode volume. This diffusion leads to deactivation at the walls. Adding more CO(,2) results in a decrease in output power, indicating that the gas has a finite optical depth and the mode volume is not pumped if too much CO(,2) is present. A model which incorporates these effects is presented. The predicted small signal gains and powers based on this model adequately match the trends observed experimentally.

  19. Fractional carbon dioxide laser in recalcitrant vulval lichen sclerosus.

    PubMed

    Lee, Andrew; Lim, Adrian; Fischer, Gayle

    2016-02-01

    Vulval lichen sclerosus is an uncommon skin condition that can usually be managed with topical corticosteroids to maintain remission. However, there is a subset of patients in whom it remains recalcitrant despite treatment with super-potent topical corticosteroids. We report a case series of four patients undergoing fractional carbon dioxide laser resurfacing and one with ablative carbon dioxide laser for severe, hyperkeratotic vulval lichen sclerosus not responding to super-potent topical corticosteroids. In these patients, carbon dioxide laser was successful in achieving remission. Their vulval lichen sclerosus was subsequently able to be maintained with topical corticosteroid treatment.

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

    PubMed

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

    2005-11-01

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

  1. Reflected laser radiation - relevance for laser safety?

    NASA Astrophysics Data System (ADS)

    Zaeh, M. F.; Braunreuther, S.; Daub, R.; Stadler, T.

    Safety is compulsory in today's production lines. Those lines often use laser material processing applications. The highest risk for the operator or a bystander of a laser application is the exposure to the direct beam. With the present laser beam intensities, an accident at least causes sudden blindness or severe burns. Even if the process works correctly, which means the beam is always oriented towards the workpiece, the scattered and reflected parts of the laser beam still can be powerful enough to cause serious harm. The state-of-the-art safety measures are passive laser safety cabins around the application. Because of the high intensities and the low beam divergence of the highly brilliant laser beam sources, they cannot guarantee a safe use of these laser applications. An option is to use active laser safety barriers that react to an impinging laser beam on its surface. A new approach to guarantee laser safety is to monitor the system and watch for incidents, to ensure that the laser spot never reaches the safety barrier. Assuming that accidents with the direct laser beam cannot occur, the passive safety measures still have to withstand the reflected laser radiation. In this paper a theoretical model is presented with which the energy distribution in a hemisphere above a deep-welding-process can be calculated. The model was calibrated and validated with intensity measurements during a welding process. The results of the measurement can be used to develop a process-tailored safety cabin. Because of the increased mobility such a system increases the flexibility of the production cell. Furthermore, the costs for laser-safety may be decreased significantly.

  2. Ultraviolet radiation induced discharge laser

    DOEpatents

    Gilson, Verle A.; Schriever, Richard L.; Shearer, James W.

    1978-01-01

    An ultraviolet radiation source associated with a suitable cathode-anode electrode structure, disposed in a gas-filled cavity of a high pressure pulsed laser, such as a transverse electric atmosphere (TEA) laser, to achieve free electron production in the gas by photoelectric interaction between ultraviolet radiation and the cathode prior to the gas-exciting cathode-to-anode electrical discharge, thereby providing volume ionization of the gas. The ultraviolet radiation is produced by a light source or by a spark discharge.

  3. "Drug-resistant granuloma faciale": treatment with carbon dioxide-GaAs laser.

    PubMed

    Paradisi, Andrea; Ricci, Francesco; Sbano, Paolo

    2016-09-01

    Granuloma faciale (GF), also known as "eosinophilic granuloma," is a rare benign leukocytoclastic vasculitis which most commonly occurs on the face of middle-aged Caucasian males. Clinically, GF appears as single or multiple, slowly growing, reddish-brown papules, nodules or plaques which may be cosmetically unpleasant. Its pathogenesis is unknown and GF is notoriously resistant to treatments. Both medical (dapsone, colchicine, gold injections, isoniazid, clofazimine, corticosteroids, psoralen ultraviolet radiation, and topical tacrolimus) and surgical therapies (excision, graft, dermabrasion, argon laser, carbon dioxide laser, pulsed dye laser, cryotherapy, and electrosurgery) have been used for GF but no effective treatment has yet been found. Furthermore, the typical facial location of GF requires an acceptable cosmetic result. We report two cases of drug-resistant GF which were successfully treated with laser vaporization combining two different wavelengths: carbon dioxide (CO2 ) 10,600 nm and GaAs 1540 nm.

  4. Use of carbon dioxide laser in oral soft tissue procedures

    PubMed Central

    Garg, Nimit; Verma, Sunil; Chadha, Minni; Rastogi, Pavitra

    2015-01-01

    Lasers have been introduced in dentistry as an alternative to conventional knife surgery. The advantage to the operator includes a clean dry field that enhances visibility and reduces the procedure time. The patient benefits by minimal postoperative pain and swelling. The paper discusses use of carbon dioxide laser in five conditions commonly encountered in oral cavity. PMID:26668460

  5. Use of carbon dioxide laser in oral soft tissue procedures.

    PubMed

    Garg, Nimit; Verma, Sunil; Chadha, Minni; Rastogi, Pavitra

    2015-01-01

    Lasers have been introduced in dentistry as an alternative to conventional knife surgery. The advantage to the operator includes a clean dry field that enhances visibility and reduces the procedure time. The patient benefits by minimal postoperative pain and swelling. The paper discusses use of carbon dioxide laser in five conditions commonly encountered in oral cavity.

  6. Characteristic measurements of silicon dioxide aerogel plasmas generated in a Planckian radiation environment

    SciTech Connect

    Dong Quanli; Wang Shoujun; Li Yutong; Zhang Yi; Zhao Jing; Wei Huigang; Shi Jianrong; Zhao Gang; Zhang Jiyan; Gu Yuqiu; Ding Yongkun; Wen Tianshu; Zhang Wenhai; Hu Xin; Liu Shenye; Zhang Lin; Tang Yongjian; Zhang Baohan; Zheng Zhijian; Nishimura, Hiroaki

    2010-01-15

    The temporally and spatially resolved characteristics of silicon dioxide aerogel plasmas were studied using x-ray spectroscopy. The plasma was generated in the near-Planckian radiation environment within gold hohlraum targets irradiated by laser pulses with a total energy of 2.4 kJ in 1 ns. The contributions of silicon ions at different charge states to the specific components of the measured absorption spectra were also investigated. It was found that each main feature in the absorption spectra of the measured silicon dioxide aerogel plasmas was contributed by two neighboring silicon ionic species.

  7. Carbon dioxide laser delivery systems in functional paranasal sinus surgery

    NASA Astrophysics Data System (ADS)

    Hoermann, Karl; Stasche, Norbert; Baker-Schreyer, Antonio; Christ, Matthias; Goedert, Paul; Foth, Hans-Jochen

    1994-02-01

    In a limited series of patients, different types of delivery systems for the carbon dioxide laser were evaluated for their clinical efficiency and practicability. The spectrum of disease submitted to laser surgery ranged from recurrent paranasal sinus polyposis to M. Osler. The systems used were an operation microscope with micromanipulator, a handpiece, two rigid, tubular waveguides and one recently developed flexible waveguide. The characteristics of each instrument are discussed, and so are the indications for endonasal laser surgery.

  8. Aesthetic Depigmentation of Gingival Smoker's Melanosis Using Carbon Dioxide Lasers.

    PubMed

    Monteiro, Luis Silva; Costa, José Adriano; da Câmara, Marco Infante; Albuquerque, Rui; Martins, Marco; Pacheco, José Júlio; Salazar, Filomena; Figueira, Fernando

    2015-01-01

    Melanic pigmentation results from melanin produced by the melanocytes present in the basal layer of the oral epithelium. One of the most common causes of oral pigmentation is smoker melanosis, a condition associated with the melanocyte stimulation caused by cigarette smoke. This paper aims to illustrate the use of a carbon dioxide laser in the removal of the gingival melanic pigmentation for aesthetic reasons in a 27-year-old female patient with history of a smoking habit. The carbon dioxide laser vaporisation was performed on the gingival mucosa with effective and quick results and without any complications or significant symptoms after the treatment. We conclude that a carbon dioxide laser could be a useful, effective, and safe instrument to treat the aesthetic complications caused by oral smoker melanosis.

  9. Spatial filtering of radiation from wire lasers

    NASA Astrophysics Data System (ADS)

    Orlova, E. E.; Solyankin, P. M.; Angeluts, A. A.; Lee, A.; Kosareva, O. G.; Ozheredov, I. A.; Balakin, A. V.; Andreeva, V. A.; Panov, N. A.; Aksenov, V. N.; Shkurinov, A. P.

    2017-04-01

    In this letter we propose an approach to obtain directive radiation from wire lasers with subwavelength transverse dimensions and length much larger than the radiation wavelength (wire lasers) based on spatial filtering of their radiation using a combination of a spherical lens and a diaphragm. Theoretical modeling based on the antenna model for wire lasers shows that a directive beam with the uniform phase front can be formed when the diaphragm separates the maximum of the image field of the laser created by the lens. We demonstrate spatial filtering of wire laser radiation experimentally using a terahertz quantum cascade laser.

  10. A high-pressure carbon dioxide gasdynamic laser

    NASA Technical Reports Server (NTRS)

    Kuehn, D. M.

    1973-01-01

    A carbon dioxide gasdynamic laser was operated over a range of reservoir pressure and temperature, test-gas mixture, and nozzle geometry. A significant result is the dominant influence of nozzle geometry on laser power at high pressure. High reservoir pressure can be effectively utilized to increase laser power if nozzle geometry is chosen to efficiently freeze the test gas. Maximum power density increased from 3.3 W/cu cm of optical cavity volume for an inefficient nozzle to 83.4 W/cu cm at 115 atm for a more efficient nozzle. Variation in the composition of the test gas also caused large changes in laser power output. Most notable is the influence of the catalyst (helium or water vapor) that was used to depopulate the lower vibrational state of the carbon dioxide. Water caused an extreme deterioration of laser power at high pressure (100 atm), whereas, at low pressure the laser for the two catalysts approached similar values. It appears that at high pressure the depopulation of the upper laser level of the carbon dioxide by the water predominates over the lower state depopulation, thus destroying the inversion.

  11. Superpulsed carbon dioxide laser: an update on cutaneous surgical applications

    NASA Astrophysics Data System (ADS)

    Wheeland, Ronald G.

    1990-06-01

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

  12. Radiative heat transfer in porous uranium dioxide

    SciTech Connect

    Hayes, S.L.

    1992-12-01

    Due to low thermal conductivity and high emissivity of UO{sub 2}, it has been suggested that radiative heat transfer may play a significant role in heat transfer through pores of UO{sub 2} fuel. This possibility was computationally investigated and contribution of radiative heat transfer within pores to overall heat transport in porous UO{sub 2} quantified. A repeating unit cell was developed to model approximately a porous UO{sub 2} fuel system, and the heat transfer through unit cells representing a wide variety of fuel conditions was calculated using a finite element computer program. Conduction through solid fuel matrix as wekk as pore gas, and radiative exchange at pore surface was incorporated. A variety of pore compositions were investigated: porosity, pore size, shape and orientation, temperature, and temperature gradient. Calculations were made in which pore surface radiation was both modeled and neglected. The difference between yielding the integral contribution of radiative heat transfer mechanism to overall heat transport. Results indicate that radiative component of heat transfer within pores is small for conditions representative of light water reactor fuel, typically less than 1% of total heat transport. It is much larger, however, for conditions present in liquid metal fast breeder reactor fuel; during restructuring of this fuel type early in life, the radiative heat transfer mode was shown to contribute as much as 10-20% of total heat transport in hottest regions of fuel.

  13. Effects of radiation on laser diodes.

    SciTech Connect

    Phifer, Carol Celeste

    2004-09-01

    The effects of ionizing and neutron radiation on the characteristics and performance of laser diodes are reviewed, and the formation mechanisms for nonradiative recombination centers, the primary type of radiation damage in laser diodes, are discussed. Additional topics include the detrimental effects of aluminum in the active (lasing) volume, the transient effects of high-dose-rate pulses of ionizing radiation, and a summary of ways to improve the radiation hardness of laser diodes. Radiation effects on laser diodes emitting in the wavelength region around 808 nm are emphasized.

  14. Laser undulated synchrotron radiation sources

    NASA Astrophysics Data System (ADS)

    Baine, Michael A. J.

    2000-07-01

    This work will address the practicality of using lasers to undulate electron beams for the production of tunable, short pulsed, monochromatic, synchrotron radiation. An x-ray source based on this mechanism, referred to as a Laser Synchrotron Source (LSS), has several attractive features: (1)x-rays can be generated with an electron beam whose energy is a factor of 100 smaller than competing synchrotron sources that use magnetic undulators, (2)the pulse length can be made extremely short (<100fs) by using short pulsed lasers, (3)the polarization can be controlled by changing the polarization of the incident laser, (4)the bandwidth can be quite narrow (<1%), and (5)the resultant x-rays are well collimated (θ < .1 rad for γ > 10) in the direction of the electron beam. These factors combine to produce one of the brightest (>1018 J/s mrad mm2 1%BW) sources of x-rays available. The most attractive feature, however, is its compact size and low cost, which suit it well for applications in Medicine, Biology, and Physics. The problem will be treated in two parts: analysis of nonlinear Thomson scattering for arbitrary interaction geometry of intense lasers and relativistic electron beams, and description of a proof-of-principle experiment carried out at the Naval Research Laboratory.

  15. Neutron radiation characteristics of plutonium dioxide fuel

    NASA Technical Reports Server (NTRS)

    Taherzadeh, M.

    1972-01-01

    The major sources of neutrons from plutonium dioxide nuclear fuel are considered in detail. These sources include spontaneous fission of several of the Pu isotopes, (alpha, n) reactions with low Z impurities in the fuel, and (alpha, n) reactions with O-18. For spontaneous fission neutrons a value of (1.95 + or - 0.07) X 1,000 n/s/g PuO2 is obtained. The neutron yield from (alpha, n) reactions with oxygen is calculated by integrating the reaction rate equation over all alpha-particle energies and all center-of-mass angles. The results indicate a neutron emission rate of (1.14 + or - 0.26) X 10,000 n/s/g PuO2. The neutron yield from (alpha, n) reactions with low Z impurities in the fuel is presented in tabular form for one part part per million of each impurity. The total neutron yield due to the combined effects of all the impurities depends upon the fractional weight concentration of each impurity. The total neutron flux emitted from a particular fuel geometry is estimated by adding the neutron yield due to the induced fission to the other neutron sources.

  16. Neutron Radiation Characteristics of Plutonium Dioxide Fuel

    NASA Technical Reports Server (NTRS)

    Taherzadeh, M.

    1972-01-01

    The major sources of neutrons from plutonium dioxide nuclear fuel are considered in detail. These sources include spontaneous fission of several of the Pu isotopes, reactions with low Z impurities in the fuel, and reactions with O-18. For spontaneous fission neutrons a value of (1.95 plus or minus 0.07) X 1,000 n/s/q PuO2 is obtained. The neutron yield from (alpha, neutron) reactions with oxygen is calculated by integrating the reaction rate equation over all alpha particle energies and all center-of-mass angles. The results indicate a neutron emission rate of (1.42 plus or minus 0.32) X 10,000 n/s/q PuO2. The neutron yield from (alpha, neutron) reactions with low Z impurities in the fuel is presented in tabular form for one part per million of each impurity. The total neutron flux emitted from a particular fuel geometry is estimated by adding the neutron yield due to the induced fission to the other neutron sources.

  17. 21 CFR 874.4500 - Ear, nose, and throat microsurgical carbon dioxide laser.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ear, nose, and throat microsurgical carbon dioxide..., nose, and throat microsurgical carbon dioxide laser. (a) Identification. An ear, nose, and throat microsurgical carbon dioxide laser is a device intended for the surgical excision of tissue from the ear, nose...

  18. 21 CFR 874.4500 - Ear, nose, and throat microsurgical carbon dioxide laser.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Ear, nose, and throat microsurgical carbon dioxide..., nose, and throat microsurgical carbon dioxide laser. (a) Identification. An ear, nose, and throat microsurgical carbon dioxide laser is a device intended for the surgical excision of tissue from the ear, nose...

  19. 21 CFR 874.4500 - Ear, nose, and throat microsurgical carbon dioxide laser.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Ear, nose, and throat microsurgical carbon dioxide..., nose, and throat microsurgical carbon dioxide laser. (a) Identification. An ear, nose, and throat microsurgical carbon dioxide laser is a device intended for the surgical excision of tissue from the ear, nose...

  20. 21 CFR 874.4500 - Ear, nose, and throat microsurgical carbon dioxide laser.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Ear, nose, and throat microsurgical carbon dioxide..., nose, and throat microsurgical carbon dioxide laser. (a) Identification. An ear, nose, and throat microsurgical carbon dioxide laser is a device intended for the surgical excision of tissue from the ear, nose...

  1. 21 CFR 874.4500 - Ear, nose, and throat microsurgical carbon dioxide laser.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Ear, nose, and throat microsurgical carbon dioxide..., nose, and throat microsurgical carbon dioxide laser. (a) Identification. An ear, nose, and throat microsurgical carbon dioxide laser is a device intended for the surgical excision of tissue from the ear, nose...

  2. Carbon dioxide laser oral safety parameters for teeth

    SciTech Connect

    Powell, G.L.; Whisenant, B.K.; Morton, T.H. )

    1990-01-01

    The carbon dioxide laser is used in the oral cavity for a variety of procedures. Although the procedures may not involve the teeth directly, precaution should be exercised to preserve their integrity. The results of this study indicate that the most limiting parameter for oral use of the CO{sub 2} laser is damage to the enamel surface, which could be inflicted with as little as 5 W for 0.2 second and a 1 mm beam. Care should be exercised to prevent inadvertent damage to the surface enamel of teeth even at very low energy levels.

  3. Carbon dioxide laser resurfacing with fast recovery.

    PubMed

    Chajchir, Abel; Benzaquen, Iliana

    2005-01-01

    ABTRACT: Long sun exposure, in addition to ozone layer damage, produces structural damase to the normal skin. Injury to the dermal collagen and elastic fiber results in facial wrinkles. Photodamage to the skin is one of the most common sources of concern for patients visiting the plastic surgeon or dermatologist. Over the years, many alternative solutions have been developed. CO2 laser treatment is one of the alternatives bringing unique benefits and satisfactory results for both patient and surgeons. However, the initial problems of emotional discomfort, prolonged postoperative recovery and delayed return to normal activities have made patients reluctant to accept this method. This article discusses single-pass CO2 laser resurfacing with lower energy. Also, it proposes a technique that does not use wet gauze to remove the surface of the skin. This technique is applied in combination with an intensive skin care treatment. Different authors propose a single pass of CO2 laser with excellent results. With the reported method, identical long-lasting benefits are achieved, but the post-operative time is shorter.

  4. Using the carbon dioxide laser for tonsillotomy in children.

    PubMed

    Linder, A; Markström, A; Hultcrantz, E

    1999-10-15

    Carbon dioxide laser tonsillotomies were performed on 33 children aged 1-12 years for the relief of obstructive symptoms due to tonsillar hyperplasia. As opposed to conventional tonsillectomy, only the protruding part of each tonsil was removed. A carbon dioxide laser delivering 20 W was used for the excision. Twenty-one children were seen in active short-term follow-up and the records of all the children were checked for possible surgery related events up to 20-33 months after surgery. Laser tonsillotomy was uniformly effective in relieving the obstruction, with good hemostasis. The tonsillar remnants healed completely within 2 weeks. No major adverse events occurred. Post-operative pain appeared slight and easily controlled. There was no gain in operating time compared with conventional tonsillectomy. The laser tonsillotomies were in most cases done in day surgery. No recurrence of obstructive problems was reported up to 20-33 months after surgery. It was concluded that tonsillotomy, using a carbon dixoide laser, is a valid treatment for obstructive symptoms caused by enlarged tonsils, which can be performed with little bleeding and post-operative pain. The improved hemostasis may enable a shift from in-patient to day surgery.

  5. Detecting radiation reaction at moderate laser intensities.

    PubMed

    Heinzl, Thomas; Harvey, Chris; Ilderton, Anton; Marklund, Mattias; Bulanov, Stepan S; Rykovanov, Sergey; Schroeder, Carl B; Esarey, Eric; Leemans, Wim P

    2015-02-01

    We propose a new method of detecting radiation reaction effects in the motion of particles subjected to laser pulses of moderate intensity and long duration. The effect becomes sizable for particles that gain almost no energy through the interaction with the laser pulse. Hence, there are regions of parameter space in which radiation reaction is actually the dominant influence on charged particle motion.

  6. Radiative lifetimes of nitrogen dioxide for excitation wavelengths from 400 to 750 nm

    SciTech Connect

    Patten, K.O. Jr.; Burley, J.D.; Johnston, H.S. )

    1990-10-04

    At room temperature, the radiative lifetimes of nitrogen dioxide excited by pulsed, tunable, dye laser radiation are measured in a 50-L flask, for excitation wavelengths ranging from 400 to 750 nm, at total pressures between 0.25 and 2.0 mTorr, and for times between 0.7 and 60 {mu}s. The data are analyzed in terms of the Stern-Volmer mechanism to give zero-pressure radiative constants (k{sub 0} = 1/{tau}{sub 0}) and empirical collisional quenching rate constants k{sub q} by ground-state nitrogen dioxide. (a) The observed radiative coefficients generally increase linearly with increasing excitation energy (cm{sup {minus}1}): k{sub 0}/s{sup {minus}1} = 0.504(E-E{sub 0}) + 7.96 {times} 10{sup 3}, where E is the excitation energy and E{sub 0} is the energy of the origin of the {sup 2}B{sub 2} excited state. At wavelengths above about 540 nm there are strong state-to-state variations of radiative lifetime, producing large apparent scatter in the data. The zero-pressure radiative lifetimes {tau}{sub 0} are compared to previous measurements and are in rough agreement with a number of earlier studies. (b) On the other hand, different investigators typically obtain different numerical values for the Stern-Volmer collisional quenching rate constants. As observed here, the quenching rate constants k{sub q} are found to vary by almost a factor of 6 as filters are changed in front of the photomultiplier tube with all other experimental conditions held constant. Some of the difficulties of observing meaningful quenching rate constants for nitrogen dioxide are discussed.

  7. Enamel fusion using a carbon dioxide laser: A technique for sealing pits and fissures

    SciTech Connect

    Walsh, L.J.; Perham, S.J. )

    1991-05-01

    The well-established enhanced resistance of lased enamel to demineralization is the basis for clinical application of the carbon dioxide laser to caries prevention. This in vitro study examined the effect of focused infrared laser radiation on sound enamel and early pit and fissure caries. Low power levels (2-5 W) induced localized melting and resolidification of enamel with little surface destruction. For sound fissures, fusion of enamel from the lateral walls of the fissure eliminated the fissure space, providing a sealant effect; while in carious fissures, carious enamel was vaporized and adjacent sound enamel fused to partially eliminate the defect. The technique for enamel fusion using CO2 lasers has potential application for sealing pits and fissures and producing physicochemical alterations in enamel which may have preventive benefits.

  8. Efficiency of Carbon Dioxide Fractional Laser in Skin Resurfacing.

    PubMed

    Petrov, Andrej

    2016-06-15

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

  9. Efficiency of Carbon Dioxide Fractional Laser in Skin Resurfacing

    PubMed Central

    Petrov, Andrej

    2016-01-01

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

  10. Measurement of Carbon Dioxide Column via Space Borne Laser Absorption

    NASA Technical Reports Server (NTRS)

    Heaps, WIlliam S.

    2007-01-01

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

  11. Reduction of thickened flap using fractional carbon dioxide laser.

    PubMed

    Brightman, Lori A; Brauer, Jeremy A; Anolik, Robert; Weiss, Elliot T; Karen, Julie; Chapas, Anne; Hale, Elizabeth; Bernstein, Leonard; Geronemus, Roy G

    2011-11-01

    The paramedian forehead flap is an excellent choice when repairing a large nasal defect. However, even when carefully thinned, the flap may develop a bulky appearance, an ill-fitting contour, or trap door deformity. When on the face, these suboptimal results can be quite distressing. Surgical and non-surgical options for improvement exist. Surgical options include additional debulking and reorientation of the flap. Non-surgical options include intralesional corticosteroids or 5-flourouracil, dermabrasion, and ablative and non-ablative laser resurfacing. Each option has limited benefit as well potential side effects. Case report. In this report, we present dramatic improvement of a thickened paramedian forehead flap using the Fraxel Re:pair, a fractional carbon dioxide (CO(2) ) laser (Solta Medical, Inc. Hayward, CA). To our knowledge, this is the first case in the literature demonstrating successful reduction of a bulky flap using a fractional ablative laser. Copyright © 2011 Wiley Periodicals, Inc.

  12. LASER SPECTROSCOPY: Measurement of the concentration ratio for 13Ñ and 12Ñ isotopes at atmospheric pressure by carbon dioxide absorption of diode laser radiation at ~2 μm

    NASA Astrophysics Data System (ADS)

    Mironchuk, E. S.; Nikolaev, I. V.; Ochkin, Vladimir N.; Rodionova, S. S.; Spiridonov, Maksim V.; Tskhai, Sergei N.

    2009-04-01

    The ratio of 12ÑO2 and 13CO2 concentrations in the human exhaled air is measured by the method of diode laser spectroscopy using a three-channel optical scheme and multipass cell. Unlike the previous measurements in the spectral range of ~4.3 μm with a resolved rotational structure at low pressure of selected samples, the present measurements are performed in the range of ~2 μm, in which weaker absorption bands of CO2 reside. In this case, it is possible to employ lasers and photodetectors operating at room temperature. The thorough simulation of the spectrum with collisional broadening of lines and employment of regression analysis allow one to take measurements at atmospheric pressure with the accuracy of ~0.04%, which satisfies the requirements to medical diagnostics of ulcers.

  13. INDUSTRIAL EFFLUENT TREATMENT USING IONIZING RADIATION COMBINED TO TITANIUM DIOXIDE

    SciTech Connect

    Duarte, C.L.; Oikawa, H.; Mori, M.N.; Sampa, M.H.O.

    2004-10-04

    The Advanced Oxidation Process (AOP) with OH radicals are the most efficient to mineralize organic compounds, and there are various methods to generate OH radicals as the use of ozone, hydrogen peroxide and ultra-violet radiation and ionizing radiation. The irradiation of aqueous solutions with high-energy electrons results in the excitation and ionizing of the molecules and rapid (10{sup -14} - 10{sup -9} s) formation of reactive intermediates. These reactive species will react with organic compounds present in industrial effluent inducing their decomposition. Titanium dioxide (TiO{sub 2}) catalyzed photoreaction is used to remove a wide range of pollutants in air and water media, combined to UV/VIS light, FeO{sub 2}, and H{sub 2}O{sub 2}, but as far as known there is no report on the combination with ionizing radiation. In some recent studies, the removal of organic pollutants in industrial effluent, such as Benzene, Toluene, and Xylene from petroleum production using ionizing radiation was investigated. It has been ob served that none of the methods can be used individually in wastewater treatment applications with good economics and high degree of energy efficiency. In the present work, the efficiency of ionizing radiation in presence of TiO{sub 2} to treat industrial effluent was evaluated. The main aim to combine these technologies is to improve the efficiency for very hard effluents and to reduce the processing cost for future implementation to large-scale design.

  14. Aerobiology of irradiation with the carbon dioxide laser.

    PubMed

    Matthews, J; Newsom, S W; Walker, N P

    1985-06-01

    The ability of a carbon dioxide laser to scatter debris and aerosolize bacteria from human skin was tested by collecting the aerosols liberated with glass impingers together with a slit sampler. Two sets of tests were done--one to detect dispersal of cells from treatment of rodent ulcers or warts, and the other on pieces of skin obtained from autopsy material, which had been injected with spores. With low power levels a few bacterial particles were collected, together with some whole cells, however, at levels greater than 750 W cm-2 all the cultures were sterile.

  15. Fractionated ablative carbon dioxide laser treatment of steatocystoma multiplex.

    PubMed

    Kassira, Sama; Korta, Dorota Z; de Feraudy, Sebastien; Zachary, Christopher B

    2016-11-01

    Steatocystoma multiplex is a well-recognized condition in which subjects develop dermal cysts generally inherited in an autosomal dominant fashion, though these can occur sporadically. This case report describes the successful treatment of a 51-year-old woman with steatocystomata limited to the face, who after two treatments with a fractionated ablative carbon dioxide laser remained free of cysts for three years. We conclude that this treatment should be considered as an efficient and effective treatment option for patients with steatocystoma multiplex.

  16. Improvement of Microstomia in Scleroderma after Carbon Dioxide Laser Treatment

    PubMed Central

    Bennani, Imane; Lopez, Raphael; Bonnet, Delphine; Prevot, Gregoire; Constantin, Arnaud; Chauveau, Dominique; Paul, Carle; Bulai Livideanu, Cristina

    2016-01-01

    Limited mouth opening (LMO) is a frequent complication of systemic sclerosis (SS). Its management is complex and there are limited treatment options. We report four patients with SS and severe LMO [interincisal distance (IID) <30 mm] treated with pulsed carbon dioxide (CO2) laser. Pulsed CO2 laser treatment of the white lips was performed after all patients had signed a written informed consent in the absence of alternative treatment. Treatment was carried out under locoregional anaesthesia using a Sharplan 30C CO2 laser in the Silk Touch® resurfacing mode. One to three laser sessions were performed at intervals of 8-12 months between sessions. Assessments were performed at 3 and 12 months with measurement of the IID using a ruler, calculation of the Mouth Handicap in Systemic Sclerosis (MHISS) scale and global evaluation by the patients. Adverse events were also reported. In all four patients, an improvement in IID occurred 3 months after the first session with a mean gain of +5 mm (range: 2-7). At 12 months, a mean gain of +8.5 mm (range: 7-10) in IID was observed. The MHISS score decreased by a mean of •14 (range: 11-17). All patients showed improvement of lip flexibility or mouth opening, allowing better phonation and mastication and easier dental care. Adverse effects were transient erythema and/or dyschromia. CO2 laser appears to be effective and well tolerated in the improvement of LMO in SS. PMID:27403126

  17. Pulsed laser radiation therapy of skin tumors

    SciTech Connect

    Kozlov, A.P.; Moskalik, K.G.

    1980-11-15

    Radiation from a neodymium laser was used to treat 846 patients with 687 precancerous lesions or benign tumors of the skin, 516 cutaneous carcinomas, 33 recurrences of cancer, 51 melanomas, and 508 metastatic melanomas in the skin. The patients have been followed for three months to 6.5 years. No relapses have been observed during this period. Metastases to regional lymph nodes were found in five patients with skin melanoma. Pulsed laser radiation may be successfully used in the treatment of precancerous lesions and benign tumors as well as for skin carcinoma and its recurrences, and for skin melanoma. Laser radiation is more effective in the treatment of tumors inaccessible to radiation therapy and better in those cases in which surgery may have a bad cosmetic or even mutilating effect. Laser beams can be employed in conjunction with chemo- or immunotherapy.

  18. EFFECTS OF LASER RADIATION ON MATTER: Spectrum of the barium atom in a laser radiation field

    NASA Astrophysics Data System (ADS)

    Bondar', I. I.; Suran, V. V.

    1990-08-01

    An experimental investigation was made of the influence of a laser radiation field on the spectrum of barium atoms. The investigation was carried out by the method of three-photon ionization spectroscopy using dye laser radiation (ω = 14 800-18 700 cm - 1). The electric field intensity of the laser radiation was 103-106 V/cm. This laser radiation field had a strong influence on a number of bound and autoionizing states. The nature of this influence depended on the ratio of the excitation frequencies of bound and autoionizing states.

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

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

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

  20. Vital parameters related low level laser radiation

    NASA Astrophysics Data System (ADS)

    Palmieri, Beniamino; Capone, Stefania

    2011-08-01

    The first work hypotesis is that biosensors on the patient detecting heart, breath rate and skin parameters, modulate laser radiation to enhance the therapeutic outcome; in the second work hypotesis: biofeedback could be effective, when integrated in the low level laser energy release.

  1. Fractional Carbon Dioxide Laser in Treatment of Acne Scars.

    PubMed

    Petrov, Andrej; Pljakovska, Vesna

    2016-03-15

    Scars appear as a result of skin damage during the process of the skin healing. There are two types of acne scars, depending on whether there is a loss or accumulation of collagen: atrophic and hypertrophic. In 80-90% it comes to scars with loss of collagen compared to smaller number of hypertrophic scars and keloids. The aim of the study was to determine efficiency and safety of fractional carbon dioxide laser in the treatment of acne scars. The study was carried out in Acibadem Sistina Clinical Hospital, Skopje at the Department of Dermatovenerology, with a total of 40 patients treated with fractional carbon dioxide laser (Lutronic eCO2). The study included patients with residual acne scars of a different type. Comedogenic and papular acne in our material were proportionately presented in 50% of cases, while the other half were the more severe clinical forms of acne - pustular inflammatory acne and nodulocystic acne that leave residual lesions in the form of second, third and fourth grade of scars. The experiences of our work confirm the world experiences that the best result with this method is achieved in dotted ice pick or V-shaped acne scars.

  2. Fractional Carbon Dioxide Laser in Treatment of Acne Scars

    PubMed Central

    Petrov, Andrej; Pljakovska, Vesna

    2016-01-01

    BACKGROUND: Scars appear as a result of skin damage during the process of the skin healing. There are two types of acne scars, depending on whether there is a loss or accumulation of collagen: atrophic and hypertrophic. In 80-90% it comes to scars with loss of collagen compared to smaller number of hypertrophic scars and keloids. AIM: The aim of the study was to determine efficiency and safety of fractional carbon dioxide laser in the treatment of acne scars. MATERIAL AND METHODS: The study was carried out in Acibadem Sistina Clinical Hospital, Skopje at the Department of Dermatovenerology, with a total of 40 patients treated with fractional carbon dioxide laser (Lutronic eCO2). The study included patients with residual acne scars of a different type. RESULTS: Comedogenic and papular acne in our material were proportionately presented in 50% of cases, while the other half were the more severe clinical forms of acne - pustular inflammatory acne and nodulocystic acne that leave residual lesions in the form of second, third and fourth grade of scars. CONCLUSION: The experiences of our work confirm the world experiences that the best result with this method is achieved in dotted ice pick or V-shaped acne scars. PMID:27275326

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

  4. Laser-induced nucleation of carbon dioxide bubbles

    NASA Astrophysics Data System (ADS)

    Ward, Martin R.; Jamieson, William J.; Leckey, Claire A.; Alexander, Andrew J.

    2015-04-01

    A detailed experimental study of laser-induced nucleation (LIN) of carbon dioxide (CO2) gas bubbles is presented. Water and aqueous sucrose solutions supersaturated with CO2 were exposed to single nanosecond pulses (5 ns, 532 nm, 2.4-14.5 MW cm-2) and femtosecond pulses (110 fs, 800 nm, 0.028-11 GW cm-2) of laser light. No bubbles were observed with the femtosecond pulses, even at high peak power densities (11 GW cm-2). For the nanosecond pulses, the number of bubbles produced per pulse showed a quadratic dependence on laser power, with a distinct power threshold below which no bubbles were observed. The number of bubbles observed increases linearly with sucrose concentration. It was found that filtering of solutions reduces the number of bubbles significantly. Although the femtosecond pulses have higher peak power densities than the nanosecond pulses, they have lower energy densities per pulse. A simple model for LIN of CO2 is presented, based on heating of nanoparticles to produce vapor bubbles that must expand to reach a critical bubble radius to continue growth. The results suggest that non-photochemical laser-induced nucleation of crystals could also be caused by heating of nanoparticles.

  5. Fractional carbon dioxide laser and plasmakinetic skin resurfacing.

    PubMed

    Groff, William F; Fitzpatrick, Richard E; Uebelhoer, Nathan S

    2008-12-01

    Photodamage is one of the most common reasons that patients visit a dermatologist's office. Carbon dioxide (CO(2)) laser resurfacing has always been the gold standard for reversing photodamage. Because of the relatively high incidence of side effects and the prolonged downtime associated with CO(2) resurfacing, new technologies have emerged to address photodamage. Portrait skin regeneration (PSR) is a novel device that has been developed to treat photodamage, and this device yields fewer side effects and downtime than traditional CO(2) laser resurfacing. At our center, we have performed more than 500 high-energy PSR treatments and have developed a unique and highly effective treatment protocol. In addition, fractional CO(2) laser resurfacing has emerged as the latest technology developed to combat photoaging. This technology yields impressive results and is much safer and causes less downtime than traditional CO(2) laser resurfacing. In this article, we will review our treatment techniques and protocols as well as address patient selection, preoperative and postoperative care, and anesthesia.

  6. Uncertainities in carbon dioxide radiative forcing in atmospheric general circulation models

    SciTech Connect

    Cess, R.D.; Zhang, M.H. ); Potter, G.L.; Gates, W.L.; Taylor, K.E. ); Colman, R.A.; Fraser, J.R.; McAvaney, B.J. ); Dazlich, D.A.; Randall, D.A. ); Del Genio, A.D.; Lacis, A.A. ); Esch, M.; Roeckner, E. ); Galin, V. ); Hack, J.J.; Kiehl, J.T. ); Ingram, W.J. ); Le Treut, H.; Lli, Z.X. ); Liang, X.Z.; Wang, W.C. ); Mahfouf,

    1993-11-19

    Global warming, caused by an increase in the concentrations of greenhouse gases, is the direct result of greenhouse gas-induced radiative forcing. When a doubling of atmospheric carbon dioxide is considered, this forcing differed substantially among 15 atmospheric general circulation models. Although there are several potential causes, the largest contributor was the carbon dioxide radiation parameterizations of the models.

  7. Uncertainties in Carbon Dioxide Radiative Forcing in Atmospheric General Circulation Models

    NASA Technical Reports Server (NTRS)

    Cess, R. D.; Zhang, M.-H.; Potter, G. L.; Gates, W. L.; Taylor, K. E.; Barker, H. W.; Colman, R. A.; Fraser, J. R.; McAvaney, B. J.; Dazlich, D. A.; Randall, D. A.; DelGenio, A. D.; Lacis, A. A.; Esch, M.; Roeckner, E.; Galin, V.; Hack, J. J.; Kiehl, J. T.; Ingram, W. J.; LeTreut, H.

    1993-01-01

    Global warming, caused by an increase in the concentrations of greenhouse gases, is the direct result of greenhouse gas-induced radiative forcing. When a doubling of atmospheric carbon dioxide is considered, this forcing differed substantially among 15 atmospheric general circulation models. Although there are several potential causes, the largest contributor was the carbon dioxide radiation parameterizations of the models.

  8. Treatment of ranula using carbon dioxide laser--case series report.

    PubMed

    Lai, J B; Poon, C Y

    2009-10-01

    Ranulas are mucus extravasation phenomenon formed after trauma to the sublingual gland or mucus retention from the obstruction of the sublingual ducts. There are various methods for treating ranulas, including marsupialization with or without open packing, excision of ranula with or without removal of sublingual gland, and laser excision and vaporization of ranula. The authors present a case series report on the use of carbon dioxide laser treatment for ranula and a literature review of cases treated using carbon dioxide laser. The authors' experience and reports in the literature indicate that carbon dioxide laser excision of ranula is safe with minimal or no recurrence.

  9. Testing Unruh Radiation with Ultraintense Lasers

    NASA Astrophysics Data System (ADS)

    Chen, Pisin; Tajima, Toshi

    1999-07-01

    We point out that using the state-of-the-art (or soon-to-be) intense electromagnetic pulses, violent accelerations that may be suitable for testing quantum field theory in curved spacetime can be realized through the interaction of a high-intensity laser with an electron. In particular, we demonstrate that the Unruh radiation is detectable, in principle, beyond the conventional radiation (most notably the Larmor radiation) background noise, by taking advantage of its specific dependence on the laser power and distinct character in spectral-angular distributions.

  10. Emitted radiation characteristics of plutonium dioxide radioisotope thermoelectric generators

    NASA Technical Reports Server (NTRS)

    Gingo, P. J.; Steyn, J. J.

    1971-01-01

    The nuclear and emitted radiation characteristics of the radioisotope elements and impurities in commercial grade plutonium dioxide are presented in detail. The development of the methods of analysis are presented. Radioisotope thermoelectric generators (RTG) of 1575, 3468 and 5679 thermal watts are characterized with respect to neutron and gamma photon source strength as well as spatial and number flux distribution. The results are presented as a function of detector position and light element contamination concentration for fuel age ranging from 'fresh' to 18 years. The data may be used to obtain results for given O-18 and Pu-236 concentrations. The neutron and gamma photon flux and dose calculations compare favorably with reported experimental values for SNAP-27.

  11. Experimental investigation of radiative thermal rectifier using vanadium dioxide

    SciTech Connect

    Ito, Kota; Nishikawa, Kazutaka; Iizuka, Hideo; Toshiyoshi, Hiroshi

    2014-12-22

    Vanadium dioxide (VO{sub 2}) exhibits a phase-change behavior from the insulating state to the metallic state around 340 K. By using this effect, we experimentally demonstrate a radiative thermal rectifier in the far-field regime with a thin film VO{sub 2} deposited on the silicon wafer. A rectification contrast ratio as large as two is accurately obtained by utilizing a one-dimensional steady-state heat flux measurement system. We develop a theoretical model of the thermal rectifier with optical responses of the materials retrieved from the measured mid-infrared reflection spectra, which is cross-checked with experimentally measured heat flux. Furthermore, we tune the operating temperatures by doping the VO{sub 2} film with tungsten (W). These results open up prospects in the fields of thermal management and thermal information processing.

  12. Average power meter for laser radiation

    NASA Astrophysics Data System (ADS)

    Shevnina, Elena I.; Maraev, Anton A.; Ishanin, Gennady G.

    2016-04-01

    Advanced metrology equipment, in particular an average power meter for laser radiation, is necessary for effective using of laser technology. In the paper we propose a measurement scheme with periodic scanning of a laser beam. The scheme is implemented in a pass-through average power meter that can perform continuous monitoring during the laser operation in pulse mode or in continuous wave mode and at the same time not to interrupt the operation. The detector used in the device is based on the thermoelastic effect in crystalline quartz as it has fast response, long-time stability of sensitivity, and almost uniform sensitivity dependence on the wavelength.

  13. [Laser radiations in medical therapy].

    PubMed

    Richand, P; Boulnois, J L

    1983-06-30

    The therapeutic effects of various types of laser beams and the various techniques employed are studied. Clinical and experimental research has shown that Helio-Neon laser beams are most effective as biological stimulants and in reducing inflammation. For this reasons they are best used in dermatological surgery cases (varicose ulcers, decubital and surgical wounds, keloid scars, etc.). Infrared diode laser beams have been shown to be highly effective painkillers especially in painful pathologies like postherpetic neuritis. The various applications of laser therapy in acupuncture, the treatment of reflex dermatologia and optic fibre endocavital therapy are presented. The neurophysiological bases of this therapy are also briefly described.

  14. Observations on pulpal response to carbon dioxide laser drilling of dentine in healthy human third molars.

    PubMed

    Nair, P N R; Baltensperger, M; Luder, H U; Eyrich, G K H

    2005-01-01

    Preservation of pulpal health is the primary prerequisite for successful application of laser systems in the hard tissue management of vital teeth. The purpose of this study was to investigate the short and long-term pulpal effects to cavity preparations in healthy human teeth using carbon dioxide (CO2) laser. A total of seven, healthy, third molars that were scheduled to be removed due to space problems were used. After the laser drilling, the occlusal cavities were closed temporarily, and the teeth were extracted 7 days (n=5) and 3 months (n=2) after the operation. The specimens were fixed, decalcified, subdivided and processed for light and transmission electron microscopy. Seven days postoperatively all the five teeth that had been irradiated with the CO2 laser did not reveal any pathological changes in the pulpo-dentine complex. Three months postoperatively the two teeth that were prepared with the laser showed subtle but distinct apposition of tertiary dentine that was lined with intact odontoblasts. One of the specimens at 3 months revealed the presence of a mild, but very circumscribed, pulpal infiltration of chronic inflammatory cells subjacent to the cavity preparation. The latter is unlikely to be due to a direct effect of the laser irradiation but a possible consequence of microleakage of oral antigens and/or other tissue-irritating molecules through the temporary restoration and the remaining dentine thickness (RDT). Although these preliminary histological results suggest that the CO2 laser under investigation induced only minimal response of the dentine-pulp complex when used as a hard-tissue drilling tool, with specific energy settings, pulse duration within thermal relaxation time and emitting radiations at 9.6 microm of wavelength, larger clinical trials involving various types of teeth are necessary to reach definite conclusions for large-scale clinical application of the laser device.

  15. Research of fiber carbon dioxide sensing system based laser absorption spectrum

    NASA Astrophysics Data System (ADS)

    Wei, Yubin; Zhang, Tingting; Li, Yanfang; Zhao, Yanjie; Wang, Chang; Liu, Tongyu

    2012-02-01

    Carbon dioxide is one of the important gas need to be detected in coal mine safety. In the mine limited ventilation environment, Concentration of carbon dioxide directly affects the health of coal miners. Carbon dioxide is also one of important signature Gas in spontaneous combustion forecasting of coal goaf area, it is important to accurately detect concentration of carbon dioxide in coal goaf area. This paper proposed a fiber carbon dioxide online sensing system based on tunable diode laser spectroscopy. The system used laser absorption spectroscopy and optical fiber sensors combined, and a near-infrared wavelength 1608nm fiber-coupled distributed feedback laser (DFB) as a light source and a 7cm length gas cell, to achieve a high sensitivity concentration detection of carbon dioxide gas. The technical specifications of sensing system can basically meet the need of mine safety.

  16. Flame imaging using planar laser induced fluorescence of sulfur dioxide

    NASA Astrophysics Data System (ADS)

    Honza, Rene; Ding, Carl-Philipp; Dreizler, Andreas; Böhm, Benjamin

    2017-09-01

    Laser induced fluorescence of sulfur dioxide (SO2-PLIF) has been demonstrated as a useful tool for flame imaging. Advantage was taken from the strong temperature dependence of the SO2 fluorescence signal. SO2 fluorescence intensity increases by more than one order of magnitude if the temperature changes from ambient conditions to adiabatic flame temperatures of stoichiometric methane-air flames. This results in a steep gradient of SO2-PLIF intensities at the reaction zone and therefore can be used as a reliable flame marker. SO2 can be excited electronically using the fourth-harmonic of an Nd:YAG laser at 266 nm. This is an attractive alternative to OH-LIF, a well-recognized flame front marker, because no frequency-doubled dye lasers are needed. This simplifies the experimental setup and is advantageous for measurements at high repetition rates where dye bleaching can become an issue. To prove the performance of this approach, SO2-PLIF measurements were performed simultaneously with OH-PLIF on laminar premixed methane-air Bunsen flames for equivalence ratios between 0.9 and 1.25. These measurements were compared to 1D laminar flamelet simulations. The SO2 fluorescence signal was found to follow the temperature rise of the flame and is located closer to the steep temperature gradient than OH. Finally, the combined SO2- and OH-PLIF setup was applied to a spark ignition IC-engine to visualize the development of the early flame kernel.

  17. Laser synchrotron radiation and beam cooling

    SciTech Connect

    Esarey, E.; Sprangle, P.; Ting, A.

    1995-12-31

    The interaction of intense {approx_gt} 10{sup 18} W/cm{sup 2}, short pulse ({approx_lt} 1 ps) lasers with electron beams and plasmas can lead to the generation of harmonic radiation by several mechanisms. Laser synchrotron radiation may provide a practical method for generating tunable, near monochromatic, well collimated, short pulse x-rays in compact, relatively inexpensive source. The mechanism for the generation of laser synchrotron radiation is nonlinear Thomson scattering. Short wavelengths can be generated via Thomson scattering by two methods, (i) backscattering from relativistic electron beams, in which the radiation frequency is upshifted by the relativistic factor 4{gamma}{sup 2}, and (ii) harmonic scattering, in which a multitude of harmonics are generated with harmonic numbers extending out to the critical harmonic number nc{approx_equal}a{sub 0}{sup 3} {much_gt} 1, where a{sub 0} {approx_equal}10{sup -9}{lambda}I{sup 1/2}, {lambda} is the laser wavelength in {mu}m and I is the laser intensity in W/cm{sup 2}. Laser synchrotron sources are capable of generating short ({approx_lt} ps) x-ray pulses with high peak flux ({approx_gt} 10{sup 21} photons/s) and brightness ({approx_gt}{sup 19} photons/s-mm{sup 2}-mrad{sup 2} 0.1%BW. As the electron beam radiates via Thomson scattering, it can subsequently be cooled, i.e., the beam emittance and energy spread can be reduced. This cooling can occur on rapid ({approximately} ps) time scales. In addition, electron distributions with sufficiently small axial energy spreads can be used to generate coherent XUV radiation via a laser-pumped FEL mechanism.

  18. Study of a carbon dioxide ring laser gyroscope

    NASA Astrophysics Data System (ADS)

    Dennis, M. L.; Diels, J.-C.; Mohebi, M.

    1992-04-01

    We have experimentally investigated a basic ring laser gyroscope (RLG) with carbon dioxide gain, and studied the prospects of developing a practical CO2 RLG. Rotation sensing was demonstrated on a number of transitions in the 9.4 μm and 10.4 μm vibration-rotation bands. Gyro response is discussed with regard to lock-in, bias, homogeneous broadening effects, and high power operation. We show that such a system may offer important advantages over standard helium-neon RLGs, including reduced quantum limit and backscattering. The prospects and possible approaches for developing a practical high power CO2 RLG are discussed, and a method of eliminating cross-saturation at high pressure is proposed and analyzed.

  19. Study of a carbon dioxide ring laser gyroscope

    NASA Astrophysics Data System (ADS)

    Dennis, M. L.; Diels, J.-C.; Mohebi, M.

    1992-04-01

    We have experimentally investigated a basic ring laser gyroscope (RLG) with carbon dioxide gain, and studied the prospects of developing a practical CO2 RLG. Rotation sensing was demonstrated on a number of transitions in the 9.4 microns and 10.4 microns vibration-rotation bands. Gyro response is discussed with regard to lock-in, bias, homogeneous broadening effects, and high power operation. We show that such a system may offer important advantages over standard helium-neon RLGs, including reduced quantum limit and backscattering. The prospects and possible approaches for developing a practical high power CO2 RLG are discussed, and a method of eliminating cross-saturation at high pressure is proposed and analyzed.

  20. Carbon dioxide laser skin resurfacing with a cooled handpiece.

    PubMed

    Moore, B A; Daamen, N; Biesman, B S; Reinisch, L

    2001-01-01

    Carbon dioxide (CO(2)) laser skin resurfacing has become an accepted procedure for the rejuvenation of aged and wrinkled facial skin. The benefits of this technique have been limited by the prolonged postoperative erythema, delayed re-epithelialization, and potential changes in pigmentation. We investigated the effects of coupling a pulsed CO(2) laser to a zinc selenide handpiece at various temperatures to cool and conduct heat from the skin surface. We compared the heat conducting handpiece to standard techniques used to determine the effects on epithelial preservation, depth of thermal damage, and new collagen growth. The dorsal aspect of piglets was treated with four handpiece arrangements: no thermally conducting window; a zinc selenide thermally conducting window at room temperature; and the zinc selenide thermally conducting window cooled to 10 and 5 degrees C. Intensities were measured to account for reflections from the surface of the handpiece. With the CO(2) laser in scanning mode and a spot size of 1 mm, each handpiece was used at intensities ranging from 8-30 W in one pass. Biopsies for histopathologic analysis and determination of the degree of epithelial damage and the depth of thermal damage were taken on days 0, 2, and 16. All specimens revealed complete re-epithelialization by day 16. The addition of a cooled handpiece did not affect either the amount of epithelial preservation or the depth of thermal damage. There is no significant advantage in using a cooled or room temperature zinc selenide handpiece for epithelial preservation or decreasing the inflammatory response in CO(2) laser resurfacing. Copyright 2001 Wiley-Liss, Inc.

  1. Laser radiation effects on Mycoplasma agalactiae

    NASA Astrophysics Data System (ADS)

    Dinu, Cerasela Z.; Grigoriu, Constantin; Dinescu, Maria; Pascale, Florentina; Popovici, Adrian; Gheorghescu, Lavinia; Cismileanu, Ana; Avram, Eugenia

    2002-08-01

    The biological effects of the laser radiation emitted by the Nd:YAG laser (second harmonic, wavelength 532 nm /fluence 32 mJ/cm2/pulse duration 6 ns) on the Mycoplasma agalactiae bacterium were studied. The radiation was found to intensify the multiplication of the bacteria irradiated in TRIS buffer (0.125 M), without however affecting the proteinic composition of the cell membrane. When the bacteria were irradiated in their growth medium (PPLO broth) being later cultivated on a solid medium (PPLO agar), the exclusive presence of the atypical colonies (granular and T-like ones) was noticed.

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

    NASA Technical Reports Server (NTRS)

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

    1970-01-01

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

  3. CONTROL OF LASER RADIATION PARAMETERS: Control of the radiation parameters of a copper vapour laser

    NASA Astrophysics Data System (ADS)

    Polunin, Yu P.; Yudin, Nikolai A.

    2003-09-01

    The possibility of controlling the pulse shape and duration and the beam divergence of a copper vapour laser operating in the mode of double pump pulses, when the first pulse excites lasing in the active medium and the second amplifies it. It is shown that a change in the delay of the second pump pulse relative to the laser pulse initiated by the first pump pulse allows an efficient control of the laser-radiation characteristics. In this case, the coefficient of laser-radiation conversion into a beam with a diffraction-limited divergence may reach ~80 %.

  4. The NASA high-power carbon dioxide laser - A versatile tool for laser applications

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

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

  5. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Microwave generation in an optical breakdown plasma created by modulated laser radiation

    NASA Astrophysics Data System (ADS)

    Antipov, A. A.; Grasyuk, Arkadii Z.; Losev, Leonid L.; Soskov, V. I.

    1990-06-01

    It was established that when laser radiation, intensity modulated at a frequency of 2.2 GHz, interacted with an optical breakdown plasma which it had created, a microwave component appeared in the thermal emf of the plasma. The amplitude of the microwave thermal emf reached 0.7 V for a laser radiation intensity of 6 GW/cm2. Laser radiation with λL = 1.06 μm was converted to the microwave range with λmω = 13 cm in the optical breakdown plasma. A microwave signal power of ~ 0.5 W was obtained from a laser power of ~ 5 MW.

  6. Low-fluence carbon dioxide laser irradiation of lentigines

    SciTech Connect

    Dover, J.S.; Smoller, B.R.; Stern, R.S.; Rosen, S.; Arndt, K.A.

    1988-08-01

    Low-fluence carbon dioxide (CO2) laser irradiation of skin has previously been shown to induce damage limited primarily to the epidermis. To evaluate whether this technique was therapeutically effective for pigmented epidermal lesions, ten lentigines caused by methoxsalen and ultraviolet light therapy were treated in one patient using the CO2 laser at fluences ranging from 3.0 to 7.7 J/cm2 for 0.1-s exposures with 4.5-mm spot size. Based on substantial clearing in seven of ten lesions treated, 146 solar lentigines were treated in five patients at fluences of 3.0, 3.7, or 4.4 J/cm2. Biopsies were performed on a total of 30 lesions immediately and 24 hours, seven days, and six weeks after irradiation. Of 125 lesions followed up clinically for six weeks, 12 cleared completely, 81 lightened substantially, and 28 remained unchanged. Only two demonstrated atrophic change. Hyperpigmentation or hypopigmentation did not occur. All lesions that improved had been treated at 3.7 or 4.4 J/cm2. Immediate histologic injury consisted of vacuolar and spindly change and subsequent vesiculation limited to the basilar epidermis. Twenty-four hours later there was epidermal necrosis with regeneration, 0.1 mm of dermal basophilia and stromal condensation, and a mild inflammatory infiltrate. These alterations were dose-dependent, with near complete epidermal necrosis and superficial dermal involvement at the highest fluence, and only focal epidermal necrosis at the lowest. At seven days, epidermal regeneration was complete with traces of melanin remaining in keratinocytes. Melanophages first appeared at seven days and persisted at six weeks, by which time the inflammatory infiltrate had cleared. No lentiginous proliferation was evident and epidermal pigmentation had become normal. Low-fluence CO2 laser irradiation is an effective means of damaging the epidermis with only minimal dermal change.

  7. Endoscopic submucosal dissection using a carbon dioxide laser with submucosally injected laser absorber solution (porcine model).

    PubMed

    Obata, Daisuke; Morita, Yoshinori; Kawaguchi, Rinna; Ishii, Katsunori; Hazama, Hisanao; Awazu, Kunio; Kutsumi, Hiromu; Azuma, Takeshi

    2013-11-01

    Recently, endoscopic submucosal dissection (ESD) has been performed to treat early gastric cancer. The en bloc resection rate of ESD has been reported to be higher than that of conventional endoscopic mucosal resection (EMR), and ESD can resect larger lesions than EMR. However, ESD displays a higher complication rate than conventional EMR. Therefore, the development of devices that would increase the safety of ESD is desired. Lasers have been extensively studied as a possible alternative to electrosurgical tools. However, laser by itself easily resulted in perforation upon irradiation of the gastrointestinal tract. We hypothesized that performing ESD using a CO2 laser with a submucosal laser absorber could be a safe and simple treatment for early gastric cancer. To provide proof of concept regarding the feasibility of ESD using a CO2 laser with submucosally injected laser absorber solution, an experimental study in ex vivo and in vivo porcine models was performed. Five endoscopic experimental procedures using a carbon dioxide (CO2) laser were performed in a resected porcine stomach. In addition, three endoscopic experimental procedures using a CO2 laser were performed in living pigs. In the ex vivo study, en bloc resections were all achieved without perforation and muscular damage. In addition, histological evaluations could be performed in all of the resected specimens. In the in vivo study, en bloc resections were achieved without perforation and muscular damage, and uncontrollable hemorrhage did not occur during the procedures. Endoscopic submucosal dissection using a CO2 laser with a submucosal laser absorber is a feasible and safe method for the treatment of early gastric cancer.

  8. Nonlinear optical properties of thick composite media with vanadium dioxide nanoparticles. I. Self-defocusing of radiation in the visible and near-IR regions

    NASA Astrophysics Data System (ADS)

    Ostrosablina, A. A.; Sidorov, A. I.

    2005-07-01

    This paper presents the experimental and theoretical results of a study of the interaction of pulsed laser radiation with thick composite media containing nanoparticles of vanadium dioxide (VO2). It establishes that the reversible semiconductor-metal phase transition that occurs in VO2 nanoparticles under the action of radiation can produce self-defocusing of radiation in the visible and near-IR regions because of the formation of a photoinduced dynamic lens. An analysis is carried out of how the radiation intensity affects the dynamics of these processes. It is shown that photoinduced absorption and scattering play a role in forming the nonlinear optical response.

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

    NASA Astrophysics Data System (ADS)

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

    2006-02-01

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

  10. Lasers pumped by solar radiation (Review)

    NASA Astrophysics Data System (ADS)

    Golger, A. L.; Klimovskii, I. I.

    1984-02-01

    Theoretical models and existing experimental data on solar-pumped lasers are surveyed. Necessary conditions for lasing to occur are defined, including the necessity that the chemical used must be stable to solar radiation. Attention is given to photodissociation gas lasers such as RI, IBr and CO2-Br2 lasers, molecular gas lasers such as CO2 devices and four-level solid-state lasers, e.g., YAG:Nd and waveguide lasers. Consideration is devoted to efficiencies optimized by the selection of specific values for the density, absorption cross-section of the active media, the rate of de-excitation, the transverse dimensions of the active medium and necessary levels of solar concentration. The discussion reveals that only the closed cycle gas dynamic laser and a solid-state waveguide laser can currently produce 3-6 percent efficiency operation, the latter requiring only 100 suns concentration for a 100 W output. Configurations of arrays of transversely concentrating parabolic heliostats to produce sufficient power for energy applications are discussed.

  11. Clinical study on 71 anorectal cases treated by carbon dioxide laser

    NASA Astrophysics Data System (ADS)

    Li, Gui-hua

    1993-03-01

    This paper describes the effective result of carbon dioxide laser on type I and II internal hemorrhoids, mixed hemorrhoids, anal fissure or fistula, etc. At present, simple hemorrhoidectomy is less acceptable to patients for its excessive bleeding and severe pain during and after the operation. Therefore, the results of 71 anorectal cases of hemorrhoidectomy using carbon dioxide laser have been observed in our hospital. The rates of effective treatment and cure were 100% and 94.3%, respectively.

  12. Low Level Laser Therapy: laser radiation absorption in biological tissues

    NASA Astrophysics Data System (ADS)

    Di Giacomo, Paola; Orlando, Stefano; Dell'Ariccia, Marco; Brandimarte, Bruno

    2013-07-01

    In this paper we report the results of an experimental study in which we have measured the transmitted laser radiation through dead biological tissues of various animals (chicken, adult and young bovine, pig) in order to evaluate the maximum thickness through which the power density could still produce a reparative cellular effect. In our experiments we have utilized a pulsed laser IRL1 ISO model (based on an infrared diode GaAs, λ=904 nm) produced by BIOMEDICA s.r.l. commonly used in Low Level Laser Therapy. Some of the laser characteristics have been accurately studied and reported in this paper. The transmission results suggest that even with tissue thicknesses of several centimeters the power density is still sufficient to produce a cell reparative effect.

  13. Maxillary frenectomy using a carbon dioxide laser in a pediatric patient: a case report.

    PubMed

    Shetty, Kishore; Trajtenberg, Cynthia; Patel, Chandni; Streckfus, Charles

    2008-01-01

    Dental lasers contribute significantly to the field of cosmetic dentistry, providing an invaluable resource for clinicians who perform different types of esthetic procedures. An increasing number of general dentists are using the carbon dioxide (CO2) laser for surgical procedures. However, the literature about using a CO2 laser to perform oral soft tissue ablation in the pediatric patient is limited. This case report presents a successful case of a maxillary labial frenectomy in a pediatric patient using a CO2 laser.

  14. Conversion of blackbody radiation into laser energy

    NASA Astrophysics Data System (ADS)

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

    1982-06-01

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

  15. Instrumental laser beam systems in navigation using scattered radiation

    NASA Astrophysics Data System (ADS)

    Oshlakov, Viktor G.

    1998-06-01

    Molecular and aerosol scattering of laser radiation, propagating in the atmosphere, makes it possible to visualize it in space. This phenomenon can be used for navigation in the navy, air force and astronautics. The laser radiation scattering is known to be used in the visual laser beam systems. The scattered laser radiations is small as compared with direct laser radiation and safe for sight. The method being developed uses the scattering effect and enables one to create the instrumental laser beam systems for pilotage alone fairways and approach canals in coastal waters and seaports.

  16. Simulation of reflected and scattered laser radiation for designing laser shields.

    PubMed

    Konieczny, Piotr; Wolska, Agnieszka; Swiderski, Jacek; Zajac, Andrzej

    2008-01-01

    This paper presents a computer simulation of reflected and scattered laser radiation for calculating the angle of laser shields performed with the Laser Shield Solver computer program. The authors describe a method of calculating the shield angle for laser shields which protect workers against reflected and scattered laser radiation and which are made from different materials. The main assumptions of the program, which calculates and simulates reflected laser radiation from any material and which can be used for designing shield angles, are presented. Calculations are compared with measurements of reflected laser radiation. The results for one type of laser and different materials which interacted with a laser beam showed that the Laser Shield Solver was an appropriate tool for designing laser shields and its simulations of reflected laser radiation distribution have practical use.

  17. A radiatively pumped CW CO2 laser

    NASA Technical Reports Server (NTRS)

    Insuik, R. J.; Christiansen, W. H.

    1984-01-01

    A proof of principle experiment to demonstrate the physics of a radiatively pumped laser has been carried out. For the first time, a blackbody cavity has optically pumped a CW CO2 laser. Results are presented from a series of experiments using mixtures of CO2, He, and Ar in which maximum output power was obtained with a 20 percent CO2-15 percent He-65 percent Ar mixture. The dependence of the output power on the blackbody temperature and the cooling gas flow rate is also discussed. By appropriately varying these parameters, continuous output powers of 8-10 mW have been achieved.

  18. Absorption of the CO laser sum frequency radiation obtained in a nonlinear crystal AgGaSe2 by molecular gases

    NASA Astrophysics Data System (ADS)

    Budilova, O. V.; Ionin, A. A.; Kinyaevskiy, I. O.; Klimachev, Yu M.; Kotkov, A. A.; Kozlov, A. Yu

    2016-11-01

    The broadband laser system based on multi-line Q-switched CO laser was experimentally studied in a nonlinear crystal AgGaSe2. The internal efficiency of sum frequency generation reached 1%. Test experiments on measurement of the absorption of the CO-laser sum frequency radiation by such gaseous substances as nitrous oxide and carbon dioxide were realized. A comparison of the experimental data with the theoretically calculated absorption spectrum of radiation was obtained.

  19. Treatment of nasal ala nodular congenital melanocytic naevus with carbon dioxide laser and Q-switched Nd:YAG laser.

    PubMed

    Zeng, Ying; Ji, Chenyang; Zhan, Kui; Weng, Weili

    2016-11-01

    Total excision of congenital melanocytic nevi (CMN) is not always feasible. We here present our experience of using carbon dioxide laser and Q-switched neodymium-doped yttrium-aluminum-garnet (Nd:YAG) laser to treat nodular CMN of the nasal ala. Q-switched Nd:YAG laser and/or carbon dioxide laser were used to treat eight cases of nasal ala nodular CMN. Carbon dioxide laser was utilized to ablate all visible melanocytic tissue within one session. Ablation was performed so as to reproduce the original anatomical contours as closely as possible. Recurrences were treated in the same way. Q-switched Nd:YAG laser was also used to irradiate all target lesions to achieve the desired end point within one session. The intervals between treatments were at least 8 weeks. Recurrence of melanocytic tissue, scar formation, pigmentation, depigmentation, and the degree of patient satisfaction were recorded at every visit. Two of the eight patients were treated with Q-switched Nd:YAG laser. Although, the lesion lightened in one of them, the hyperplastic tissue persisted. Eventually, these two patients, along with the remaining six patients, were successfully treated with a carbon dioxide laser. We recommend carbon dioxide laser treatment for nodular nasal CMN. This simple treatment does not involve skin flap transplantation and has good cosmetic outcomes. Although Q-switched Nd:YAG laser does lighten some nasal nodular CMNs, it does not eradicate the hyperplastic tissue, and is therefore not an effective treatment for nodular nasal CMN.

  20. CONTROL OF LASER RADIATION PARAMETER: Dependence of polarisation of radiation of a linear Nd:YAG laser on the pump radiation polarisation

    NASA Astrophysics Data System (ADS)

    Kravtsov, Nikolai V.; Lariontsev, E. G.; Naumkin, Nikolai I.

    2004-09-01

    The dependence of polarisation characteristics of radiation of a linear Nd:YAG laser on polarisation of radiation of a pump diode laser is studied experimentally and theoretically. It is shown that, in the case of polarisation isotropy of the optical resonator, the polarisation of radiation of the Nd:YAG laser is completely determined by the polarisation of pump radiation. Based on the vector model of this laser pumped by polarised radiation, an analytic solution describing stationary lasing is obtained.

  1. Efficient material treatment by axi-symmetrically polarized laser radiation

    NASA Astrophysics Data System (ADS)

    Makin, V. S.; Pestov, Yu I.; Makin, R. S.

    2016-08-01

    Recent years the increased interest is to the problem of interaction of nontraditionally polarized laser radiation with condensed media. The experiments with axisymmetrical polarization attract more attention. The peculiarities of interaction of axisymmetrical laser radiation with condensed matter are considered in framework of universal polariton model. It is shown that more effective is interaction of radially polarized laser radiation with surface active media. The optical schemes for efficient material treatment by radially polarized radiation are sketched.

  2. Multifocal terahertz radiation by intense lasers in rippled plasma

    NASA Astrophysics Data System (ADS)

    Gill, Reenu; Singh, Divya; Malik, Hitendra K.

    2017-06-01

    This paper presents a theoretical model for the generation of terahertz radiation by cosh-Gaussian laser beams of high intensity, which are capable of creating relativistic-ponderomotive nonlinearity. We find the components of the terahertz radiation for the relativistic laser plasma interaction, i.e. beating of the two lasers of same amplitude and different frequency in under dense plasma. We plot the electric field profile of the emitted radiation under the effect of lasers index. By creating a dip in peak of the incident lasers' fields, we can achieve multifocal terahertz radiation.

  3. LASCAT - DESIGN OF CATALYTIC MONOLITHS FOR CLOSED-CYCLE CARBON DIOXIDE LASERS

    NASA Technical Reports Server (NTRS)

    Guinn, K.

    1994-01-01

    Pulsed carbon dioxide lasers are useful in many areas, including aeronautics, space research, and weather monitoring. Most applications require a closed-cycle carbon dioxide laser, which is more portable and self-sustaining than an open-cycle system. Without a fresh carbon dioxide supply and provisions for byproduct disposal, the closed-cycle laser must recycle the carbon monoxide and oxygen gas produced by the lasing of carbon dioxide. The recombination of the carbon monoxide and oxygen gas byproducts to form a constant supply of carbon dioxide requires an active catalyst, which must be carefully designed to optimize laser performance in accordance with design requirements specific to the laser's application. LASCAT (Design of Catalytic Monoliths for Closed-Cycle Carbon Dioxide Lasers) aids in the design of the monolith catalyst by simulating the results of design decisions on the performance of the laser. In portable laser systems, considerations of size, weight, and cost are critical. LASCAT provides the opportunity for the designer to explore trade-offs between the catalyst activity, catalyst dimensions, monolith dimensions, pressure drop (a result of gas flow through the monolith), Oxygen gas conversion, and other variables. The program uses a flexible, simplified model of the monolith catalyst designed to determine the bulk-avarage gas temperature, composition, and pressure along its length. The user specifies values for the several parameters which define the catalyst's operating conditions, including monolith dimensions, gas inlet properties, thermal operation properties, and catalyst properties. LASCAT provides results which indicate whether the experimental design meets user-defined constraints such as limits on conversion rate, maximum gas temperature, and monolith weight. LASCAT is written in FORTRAN 77 and is designed for use with any text or character-based terminal or computer display. The program requires roughly 40 KB memory. LASCAT was developed

  4. Cascaded frequency doublers for broadband laser radiation

    SciTech Connect

    Andreev, N F; Vlasova, K V; Davydov, V S; Kulikov, S M; Makarov, A I; Sukharev, Stanislav A; Freidman, Gennadii I; Shubin, S V

    2012-10-31

    A new scheme of a cascaded converter of the first harmonic of broadband cw laser radiation into the second harmonic (SH) with compensation for the group walk-off in cascades is proposed and investigated. The conditions under which high conversion coefficients of broadband ({approx}33 cm{sup -1}) single-mode fibre laser radiation with low peak power ({approx}300 W) into the SH are determined for frequency doublers based on the most promising LBO crystal. Conversion of cw radiation with an average power of 300 W and efficiency {eta} = 4.5 % into the SH is obtained in a single LBO crystal. Effect of coherent addition of SH radiation excited in different cascades is demonstrated for two- and three-stage schemes. The expected conversion efficiencies, calculated disregarding loss but taking into account real aberrations of elements, are 18 % and 38 %, respectively. The effect of pumping depletion begins to manifest itself in the third cascade of a three-stage converter; it may reduce the latter value to {approx}30 %. (nonlinear optical phenomena)

  5. Radiative efficiency of MOCVD grown QD lasers

    NASA Astrophysics Data System (ADS)

    Mawst, Luke; Tsvid, Gene; Dudley, Peter; Kirch, Jeremy; Park, J. H.; Kim, N.

    2010-02-01

    The optical spectral gain characteristics and overall radiative efficiency of MOCVD grown InGaAs quantum dot lasers have been evaluated. Single-pass, multi-segmented amplified spontaneous emission measurements are used to obtain the gain, absorption, and spontaneous emission spectra in real units. Integration of the calibrated spontaneous emission spectra then allows for determining the overall radiative efficiency, which gives important insights into the role which nonradiative recombination plays in the active region under study. We use single pass, multi-segmented edge-emitting in which electrically isolated segments allow to vary the length of a pumped region. In this study we used 8 section devices (the size of a segment is 50x300 μm) with only the first 5 segments used for varying the pump length. The remaining unpumped segments and scribed back facet minimize round trip feedback. Measured gain spectra for different pump currents allow for extraction of the peak gain vs. current density, which is fitted to a logarithmic dependence and directly compared to conventional cavity length analysis, (CLA). The extracted spontaneous emission spectrum is calibrated and integrated over all frequencies and modes to obtain total spontaneous radiation current density and radiative efficiency, ηr. We find ηr values of approximately 17% at RT for 5 stack QD active regions. By contrast, high performance InGaAs QW lasers exhibit ηr ~50% at RT.

  6. Quenching of nitrogen dioxide fluorescence excited by a He-Cd laser

    SciTech Connect

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

    1994-06-01

    The effect of some buffer gases on nitrogen dioxide fluorescence excited by a 0.44-{mu}m He-Cd laser is investigated. The rate constants of fluorescence self-quenching by buffer gases are measured. The cross sections of collision quenching of fluorescence are determined. The obtained results can be used for nitrogen dioxide monitoring in the atmosphere. 12 refs., 3 figs., 1 tab.

  7. Laser cooling by collisional redistribution of radiation.

    PubMed

    Vogl, Ulrich; Weitz, Martin

    2009-09-03

    The general idea that optical radiation may cool matter was put forward 80 years ago. Doppler cooling of dilute atomic gases is an extremely successful application of this concept. More recently, anti-Stokes cooling in multilevel systems has been explored, culminating in the optical refrigeration of solids. Collisional redistribution of radiation has been proposed as a different cooling mechanism for atomic two-level systems, although experimental investigations using moderate-density gases have not reached the cooling regime. Here we experimentally demonstrate laser cooling of an atomic gas based on collisional redistribution of radiation, using rubidium atoms in argon buffer gas at a pressure of 230 bar. The frequent collisions in the ultradense gas transiently shift a highly red-detuned laser beam (that is, one detuned to a much lower frequency) into resonance, whereas spontaneous decay occurs close to the unperturbed atomic resonance frequency. During each excitation cycle, kinetic energy of order k(B)T-that is, the thermal energy (k(B), Boltzmann's constant; T, temperature)-is extracted from the dense atomic sample. In a proof-of-principle experiment with a thermally non-isolated sample, we demonstrate relative cooling by 66 K. The cooled gas has a density more than ten orders of magnitude greater than the typical values used in Doppler-cooling experiments, and the cooling power reaches 87 mW. Future applications of the technique may include supercooling beyond the homogeneous nucleation temperature and optical chillers.

  8. Thermal effects of the Nd:YAG and carbon dioxide lasers on the central nervous system.

    PubMed

    Burke, L; Rovin, R A; Cerullo, L J; Brown, J T

    1985-01-01

    The use of laser is becoming commonplace in neurological surgery because of the potential for surgical precision with minimal surrounding trauma, improved hemostasis, freedom from electrical interference of evoked potentials recordings, and a variety of other benefits. Despite this enthusiasm, there are little significant data regarding various laser-neural tissue interactions. Thermal transformation was studied using both carbon dioxide and Nd: YAG lasers on rat cerebral cortex. The Nd: YAG laser produced a significant quantity of heat which spread far beyond the boundaries of the histologically identified lesion. The thermal profile of the carbon dioxide laser on brain indicated minimal thermal spread change, even immediately adjacent to the physical edge of the lesion. Mechanisms and ramifications are discussed.

  9. Minocycline pigmentation following carbon dioxide laser resurfacing: treatment with the Q-switched Nd:YAG laser.

    PubMed

    Bernstein, Eric F; Koblenzer, Caroline; Elenitsas, Rosalie

    2015-04-01

    Minocycline is among the most common drugs to cause drug-induced pigmentation. Dermal deposition of drug metabolites typically occurs in areas of vascular leakage, such as surrounding lower extremity spider veins, within erythema associated with solar elastosis, and in areas of bruising. The skin affected by minocycline pigmentation typically takes on a slate-gray coloring in affected areas. The current patient developed minocycline pigmentation after carbon dioxide laser resurfacing of her upper lip to treat rhytides in the laser-treated area. Laser treatment with the 1,064 nm, Q-switched Nd:YAG laser was able to remove the pigmentation.

  10. On the role of nitrogen dioxide in the absorption of solar radiation

    NASA Astrophysics Data System (ADS)

    Solomon, S.; Portmann, R. W.; Sanders, R. W.; Daniel, J. S.; Madsen, W.; Bartram, B.; Dutton, E. G.

    1999-05-01

    Direct measurements of the absorption of downwelling visible radiation by nitrogen dioxide are presented. The data show that this gas can contribute significantly to local radiative forcing under certain conditions. The observed enhancements in nitrogen dioxide absorption are likely to be due both to pollution and to production by lightning in convective clouds. Case studies of several days of observations in Colorado reveal peak absorption of downwelling radiation by NO2 of up to 5-12%, corresponding to an estimated local radiative forcing that is likely to be in the range of 5-30 W/m2. The amount of local forcing associated with thunderstorm activity depends strongly upon the cloud optical depth and on where the NO2 resides within the clouds. These case studies suggest that NO2 can play a significant role in the absorption of radiation (including but not limited to anomalous cloud absorption) either under polluted conditions or when electrically active storms are considered.

  11. Analytical Characterization of CFRP Laser Treated by Excimer Laser Radiation

    NASA Astrophysics Data System (ADS)

    Kreling, S.; Fischer, F.; Delmdahl, R.; Gäbler, F.; Dilger, K.

    Due to the increasing interest in lightweight structures, carbon-fiber reinforced plastics are increasingly applied, especially in the transportation industry. An interesting technology for joining these materials is adhesive bonding due to numerous advantages compared to conventional techniques like riveting. However, to achieve a strong and durable bond, surface pre-treatment is necessary to remove residues of release agents that are transferred to the surface during manufacturing. This paper describes analytical experiments, namely SEM and XPS, performed on CFRP surfaces pre-treated with 308 nm excimer laser radiation.

  12. Wound healing in porcine skin following low-output carbon dioxide laser irradiation of the incision

    SciTech Connect

    Robinson, J.K.; Garden, J.M.; Taute, P.M.; Leibovich, S.J.; Lautenschlager, E.P.; Hartz, R.S.

    1987-06-01

    Wound healing of scalpel incisions to the depth of adipose tissue closed with conventional methods was compared with closure by low-output carbon dioxide laser irradiation. In 3 Pitman-Moore minipigs wound healing was evaluated at intervals from 1 to 90 days by the following methods: clinical variables of wound healing; formation of the basement membrane components bullous pemphigoid antigen, laminin, and fibronectin; and histological evaluation of the regeneration of the epidermis, neovascularization, and elastin and collagen formation. There was no significant difference in healing between wounds closed by the various conventional methods and by the low-output carbon dioxide laser.

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

    PubMed

    Osman, Mai Abdel Raouf; Kassab, Ahmed Nazmi

    2017-08-01

    A verrucous epidermal nevus (VEN) is a skin disorder that has been treated using different treatment modalities with varying results. Ablative lasers such as carbon dioxide laser (CO2) and erbium:yttrium-aluminum-garnet (Er:YAG) laser have been considered as the gold standard for the treatment of epidermal nevi. To evaluate and compare the efficacy, postoperative wound healing and side effects of pulsed CO2 laser and Er:YAG laser for the treatment of verrucous epidermal nevi. Twenty patients with localized VEN were randomly divided into two groups. Group 1 was administered CO2 laser and group 2 underwent Er:YAG laser treatment. A blinded physician evaluated the photographs and dermoscopic photomicrographs for the efficacy and possible side effects. All patients received one treatment session and were followed up over a 6-month period. Both lasers induced noticeable clinical improvement, but there were no significant differences between two lasers in treatment response, patient satisfaction, duration of erythema and side effects. The average time to re-epithelialization was 13.5 days with CO2 and 7.9 days with Er:YAG laser (p< .0005). No scarring was observed in Er:YAG laser group and no lesional recurrence was detected in CO2 laser group since treatment. Apart from re-epithelialization, both lasers showed equivalent outcomes with respect to treatment response, patient satisfaction, side effects and complications.

  14. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Subsonic radiation waves in neon

    NASA Astrophysics Data System (ADS)

    Loseva, T. V.; Nemchinov, I. V.

    1989-02-01

    Numerical methods are used to investigate the propagation of plane subsonic radiation waves in neon from an obstacle in the direction opposite to the incident radiation of Nd and CO2 lasers. An analysis is made of the influence of the power density of the incident radiation (in the range 10-100 MW/cm2) and of the initial density of neon (beginning from the normal valuep ρ0 up to 10ρ0) on the various characteristics of subsonic radiation waves. It is shown that waves traveling in neon can provide an effective source of radiation with a continuous spectrum and an efficiency of ~ 12-27% in the ultraviolet range (with a characteristic photon energy ~ 5-10 eV).

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

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  16. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Spatial distribution of laser radiation scattered in a plasma formed by optical breakdown of a gas

    NASA Astrophysics Data System (ADS)

    Bufetov, Igor'A.; Bufetova, G. A.; Fyodorov, V. B.

    1994-12-01

    Spatial distributions of laser radiation scattered by a laser spark were determined at different laser radiation wavelengths (λ = 1060, 530, 353, and 265 nm) and gas pressures (air at 10-760 Torr). An interference structure of the cone of the scattered radiation behind the spark was detected for the first time. The structure was attributed to interference of the radiation scattered in two or more self-focusing centres in the laser-spark plasma in air. The dependences of the maximum scattering angle on the gas pressure and on the laser radiation wavelength were determined experimentally.

  17. Bifluorophores - radiation transformers of excimeric lasers

    SciTech Connect

    Samsonova, L.C.; Afanasiadi, L.S.; Degtyarenko, K.M.; Kopylova, T.N.; Tarasenko, V.F.; Turr, I.N.

    1985-12-01

    This article describes the method of transformation of radiation as the result of intramolecular energy transfer in molecules called bifluorophores. The aim of this work was to study the spectral luminescent properties of oxazole, its equimolar mixtures and bifluorophore systems based on them, and also the possibilities of transformation using them of the radiation of the XeCl laser into the blue-green region of the spectrum. The power of the laser reached 1 MW, the pulse duration at the half-height was 20-30 nsec, and the pulse repetition frequency was 1 Hz. The generation properties of the molecules in the solutions were studied on an apparatus described in detail. A lateral variant of the excitation was used, and the resonator was formed by a dull mirror and the surface of the cuvette. The spectral-luminescent properties were studied on a Specord UV-VIS spectrophotometer and a fluorimeter mounted on the base of a SF4A monochromator.

  18. Radiation-reaction trapping of electrons in extreme laser fields.

    PubMed

    Ji, L L; Pukhov, A; Kostyukov, I Yu; Shen, B F; Akli, K

    2014-04-11

    A radiation-reaction trapping (RRT) of electrons is revealed in the near-QED regime of laser-plasma interaction. Electrons quivering in laser pulse experience radiation reaction (RR) recoil force by radiating photons. When the laser field reaches the threshold, the RR force becomes significant enough to compensate for the expelling laser ponderomotive force. Then electrons are trapped inside the laser pulse instead of being scattered off transversely and form a dense plasma bunch. The mechanism is demonstrated both by full three-dimensional particle-in-cell simulations using the QED photonic approach and numerical test-particle modeling based on the classical Landau-Lifshitz formula of RR force. Furthermore, the proposed analysis shows that the threshold of laser field amplitude for RRT is approximately the cubic root of laser wavelength over classical electron radius. Because of the pinching effect of the trapped electron bunch, the required laser intensity for RRT can be further reduced.

  19. Laser plasma influence on the space-time structure of powerful laser radiation

    NASA Astrophysics Data System (ADS)

    Ananyin, O. B.; Bogdanov, G. S.; Vovchenko, E. D.; Gerasimov, I. A.; Kuznetsov, A. P.; Melekhov, A. P.

    2016-01-01

    This paper deals with the influence of laser plasma on the structure of the radiation field of a powerful Nd-glass laser with pulse energy up to 30 J and with the diameter of the output beam 45 mm. Laser plasma is generated by focusing the laser radiation on a low-density target such as nylon mesh and teflon or mylar films. Temporal profile of the laser pulse with a total duration of 25 ns consists of a several short pulse train. Duration of each pulse is about 2 ns. Notable smoothing of spatially non-uniform radiation structure was observed in the middle of the laser pulse.

  20. Focusers of obliquely incident laser radiation

    NASA Astrophysics Data System (ADS)

    Goncharskiy, A. V.; Danilov, V. A.; Popov, V. V.; Prokhorov, A. M.; Sisakyan, I. N.; Sayfer, V. A.; Stepanov, V. V.

    1984-08-01

    Focusing obliquely incident laser radiation along a given line in space with a given intensity distribution is treated as a problem of synthesizing a mirror surface. The intricate shape of such a surface, characterized by a function z= z (u,v) in the approximation of geometrical optics, is determined from the equation phi (u,v,z) - phi O(u,v,z)=O, which expresses that the incident field and the reflected field have identical eikonals. Further calculations are facilitated by replacing continuous mirror with a more easily manufactured piecewise continuous one. The problem is solved for the simple case of a plane incident wave with a typical iconal phi O(u,v,z)= -z cos0 at a large angle to a focus mirror in the z-plane region. Mirrors constructed on the basis of the theoretical solution were tested in an experiment with a CO2 laser. A light beam with Gaussian intensity distribution was, upon incidence at a 45 deg angle, focused into a circle or into an ellipse with uniform intensity distribution. Improvements in amplitudinal masking and selective tanning technology should reduce energy losses at the surface which results in efficient laser focusing mirrors.

  1. Radiating electron source generation in ultraintense laser-foil interactions

    SciTech Connect

    Capdessus, R. King, M.; McKenna, P.

    2016-08-15

    A radiating electron source is shown to be created by a laser pulse (with intensity of 10{sup 23 }W/cm{sup 2} and duration equal to 30 fs) interacting with a near-critical density plasma. It is shown that the back radiation reaction resulting from high energy synchrotron radiation tends to counteract the action of the ponderomotive force. This enhances the collective dynamics of the radiating electrons in the highest field areas, resulting in the production of a compact radiation source (containing 80% of the synchrotron radiation emission), with an energy on the order of tens of MeV over the laser pulse duration. These phenomena are investigated using a QED-particle-in-cell code, and compared with a kinetic model accounting for the radiation reaction force in the electron distribution function. The results shed new light on electron-photon sources at ultra-high laser intensities and could be tested on future laser facilities.

  2. Tuning of betatron radiation in laser-plasma accelerators via multimodal laser propagation through capillary waveguides

    NASA Astrophysics Data System (ADS)

    Curcio, A.; Giulietti, D.; Petrarca, M.

    2017-02-01

    The betatron radiation from laser-plasma accelerated electrons in dielectric capillary waveguides is investigated. The multimode laser propagation is responsible for a modulated plasma wakefield structure, which affects the electron transverse dynamics, therefore influencing the betatron radiation spectra. Such a phenomenon can be exploited to tune the energy spectrum of the betatron radiation by controlling the excitation of the capillary modes.

  3. Ultrastructural study of thyroid capillaries after IR laser radiation

    NASA Astrophysics Data System (ADS)

    Vidal, Lourdes; Perez de Vargas, I.; Carrillo, F.; Parrado, C.; Pelaez, A.

    1994-02-01

    Laser radiation causes microscopical changes in the follicular cells relative to dose intensity. So, we have observed focal degenerative phenomena, at maximal doses, and activation of cellular function similar to the ones observed after stimulation with TSH, at minimal doses. In order to evaluate the evolution of these changes we have planned an ultrastructural study of rats thyroid capillaries treated with IR laser radiation.

  4. Laser method for simulating the transient radiation effects of semiconductor

    NASA Astrophysics Data System (ADS)

    Li, Mo; Sun, Peng; Tang, Ge; Wang, Xiaofeng; Wang, Jianwei; Zhang, Jian

    2017-05-01

    In this paper, we demonstrate the laser simulation adequacy both by theoretical analysis and experiments. We first explain the basic theory and physical mechanisms of laser simulation of transient radiation effect of semiconductor. Based on a simplified semiconductor structure, we describe the reflection, optical absorption and transmission of laser beam. Considering two cases of single-photon absorption when laser intensity is relatively low and two-photon absorption with higher laser intensity, we derive the laser simulation equivalent dose rate model. Then with 2 types of BJT transistors, laser simulation experiments and gamma ray radiation experiments are conducted. We found good linear relationship between laser simulation and gammy ray which depict the reliability of laser simulation.

  5. Photocatalytic ROS production and phototoxicity of titanium dioxide nanoparticles is dependent on solar UV radiation spectrum

    EPA Science Inventory

    Generation of reactive oxygen species (ROS) by titanium dioxide nanoparticles (nano-TiO2) and its consequent phototoxicity to Daphnia magna were measured under different solar UV radiation spectrum by applying a series of optical filters in a solar simulator. Removing UVB (280-32...

  6. Photocatalytic ROS production and phototoxicity of titanium dioxide nanoparticles is dependent on solar UV radiation spectrum

    EPA Science Inventory

    Generation of reactive oxygen species (ROS) by titanium dioxide nanoparticles (nano-TiO2) and its consequent phototoxicity to Daphnia magna were measured under different solar UV radiation spectrum by applying a series of optical filters in a solar simulator. Removing UVB (280-32...

  7. Laser-plasma-based Space Radiation Reproduction in the Laboratory

    PubMed Central

    Hidding, B.; Karger, O.; Königstein, T.; Pretzler, G.; Manahan, G. G.; McKenna, P.; Gray, R.; Wilson, R.; Wiggins, S. M.; Welsh, G. H.; Beaton, A.; Delinikolas, P.; Jaroszynski, D. A.; Rosenzweig, J. B.; Karmakar, A.; Ferlet-Cavrois, V.; Costantino, A.; Muschitiello, M.; Daly, E.

    2017-01-01

    Space radiation is a great danger to electronics and astronauts onboard space vessels. The spectral flux of space electrons, protons and ions for example in the radiation belts is inherently broadband, but this is a feature hard to mimic with conventional radiation sources. Using laser-plasma-accelerators, we reproduced relativistic, broadband radiation belt flux in the laboratory, and used this man-made space radiation to test the radiation hardness of space electronics. Such close mimicking of space radiation in the lab builds on the inherent ability of laser-plasma-accelerators to directly produce broadband Maxwellian-type particle flux, akin to conditions in space. In combination with the established sources, utilisation of the growing number of ever more potent laser-plasma-accelerator facilities worldwide as complementary space radiation sources can help alleviate the shortage of available beamtime and may allow for development of advanced test procedures, paving the way towards higher reliability of space missions. PMID:28176862

  8. Laser-plasma-based Space Radiation Reproduction in the Laboratory

    NASA Astrophysics Data System (ADS)

    Hidding, B.; Karger, O.; Königstein, T.; Pretzler, G.; Manahan, G. G.; McKenna, P.; Gray, R.; Wilson, R.; Wiggins, S. M.; Welsh, G. H.; Beaton, A.; Delinikolas, P.; Jaroszynski, D. A.; Rosenzweig, J. B.; Karmakar, A.; Ferlet-Cavrois, V.; Costantino, A.; Muschitiello, M.; Daly, E.

    2017-02-01

    Space radiation is a great danger to electronics and astronauts onboard space vessels. The spectral flux of space electrons, protons and ions for example in the radiation belts is inherently broadband, but this is a feature hard to mimic with conventional radiation sources. Using laser-plasma-accelerators, we reproduced relativistic, broadband radiation belt flux in the laboratory, and used this man-made space radiation to test the radiation hardness of space electronics. Such close mimicking of space radiation in the lab builds on the inherent ability of laser-plasma-accelerators to directly produce broadband Maxwellian-type particle flux, akin to conditions in space. In combination with the established sources, utilisation of the growing number of ever more potent laser-plasma-accelerator facilities worldwide as complementary space radiation sources can help alleviate the shortage of available beamtime and may allow for development of advanced test procedures, paving the way towards higher reliability of space missions.

  9. Laser-plasma-based Space Radiation Reproduction in the Laboratory.

    PubMed

    Hidding, B; Karger, O; Königstein, T; Pretzler, G; Manahan, G G; McKenna, P; Gray, R; Wilson, R; Wiggins, S M; Welsh, G H; Beaton, A; Delinikolas, P; Jaroszynski, D A; Rosenzweig, J B; Karmakar, A; Ferlet-Cavrois, V; Costantino, A; Muschitiello, M; Daly, E

    2017-02-08

    Space radiation is a great danger to electronics and astronauts onboard space vessels. The spectral flux of space electrons, protons and ions for example in the radiation belts is inherently broadband, but this is a feature hard to mimic with conventional radiation sources. Using laser-plasma-accelerators, we reproduced relativistic, broadband radiation belt flux in the laboratory, and used this man-made space radiation to test the radiation hardness of space electronics. Such close mimicking of space radiation in the lab builds on the inherent ability of laser-plasma-accelerators to directly produce broadband Maxwellian-type particle flux, akin to conditions in space. In combination with the established sources, utilisation of the growing number of ever more potent laser-plasma-accelerator facilities worldwide as complementary space radiation sources can help alleviate the shortage of available beamtime and may allow for development of advanced test procedures, paving the way towards higher reliability of space missions.

  10. LASER PLASMA AND LASER APPLICATIONS: Soft apertures for lasers emitting visible radiation

    NASA Astrophysics Data System (ADS)

    Kolerov, A. N.; Arzumanyan, Sh O.; Chirkina, K. P.; Gritsaĭ, I. I.

    1988-12-01

    It was found that an Al2O3:Ti3+ crystal grown by the Verneuil method can be used in the fabrication of "soft" apertures for lasers emitting in the blue-green range. The experimental results indicated equalization of the intensity of the radiation across the laser beam and also "polychromatic" lasing when apertures made of Al2O3:Ti3+ were placed inside the resonator cavity.

  11. Cervical osteomyelitis after carbon dioxide laser excision of recurrent carcinoma of the posterior pharyngeal wall.

    PubMed

    Timmermans, A Jacqueline; Brandsma, Dieta; Smeele, Ludi E; Rosingh, Andert W; van den Brekel, Michiel W M; Lohuis, Peter J F M

    2013-04-01

    Two patients with recurrent carcinoma of the posterior pharyngeal wall, previously treated with carbon dioxide (CO2) laser excision and (chemo)radiotherapy, presented with neck pain due to cervical osteomyelitis. In one patient this led to cervical spine instability, for which a haloframe was applied. Our working hypothesis was that cervical osteomyelitis was caused by an infected wound bed induced by CO2 laser excision of the tumor in the already vascular-compromised area of the irradiated posterior pharyngeal wall. We discuss the risks of leaving a wound for secondary granulation after CO2 laser excision of the posterior pharyngeal wall and prophylactic antibiotic treatment.

  12. Diffuse Urticarial Reaction Associated with Titanium Dioxide Following Laser Tattoo Removal Treatments.

    PubMed

    Willardson, Hal Bret; Kobayashi, Todd T; Arnold, Jason G; Hivnor, Chad M; Bowen, Casey D

    2017-03-01

    Local and generalized allergic reactions following laser tattoo removal have been documented, but are rare. To our knowledge, this is the fourth documented case of widespread urticarial eruptions following laser tattoo removal treatment. Unlike previously documented cases, this patient's reaction was found to be associated with titanium dioxide within the tattoo and her symptoms were recalcitrant to medical therapy. A 46-year-old female experienced diffuse urticarial plaques, erythema, and pruritis following multiple laser tattoo removal treatments with an Nd:YAG laser. The systemic allergic reaction was recalcitrant to increasing doses of antihistamines and corticosteroids. The tattoo was finally surgically excised. The excised tissue was analyzed by scanning electron microscopy and energy-dispersive X-ray analysis and contained high levels of titanium dioxide. Two weeks following the excision, and without the use of medical therapy, the patient had complete resolution of her generalized urticaria. Ours is the first documented case of a diffuse urticarial reaction following laser tattoo removal treatments that shows a strong association to titanium dioxide within the tattoo pigment. Herein, we describe a novel surgical approach to treat recalcitrant generalized allergic reaction to tattoo pigment.

  13. Analysis of plume emissions after papovavirus irradiation with the carbon dioxide laser

    SciTech Connect

    Bellina, J.H.; Stjernholm, R.L.; Kurpel, J.E.

    1982-05-01

    This study was undertaken to evaluate potential inhalation hazards to operating room personnel after irradiation of tumors with the carbon dioxide laser. Cellular debris was analyzed for viability using labeled nucleotides and labeled glucose. In this way the plume was investigated for the presence of material with oncogenic potential. Most surgeons who have ablated venereal warts or certain tumors with the carbon dioxide laser have worried about possible hazards of inhaling the vapor that is produced as a result of their work. We utilized three methods to determine whether viable particles exist in the laser plume. Fortunately, it is most comforting that the metabolic studies, DNA and RNA studies and cytologic studies seem to indicate that the plume is biologically inactive.

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

    SciTech Connect

    Masina, B. N. E-mail: slafane@cdta.dz; Lafane, S. E-mail: slafane@cdta.dz; Abdelli-Messaci, S.; Kerdja, T.; Wu, L.; Akande, A. A.; Mwakikunga, B.

    2015-10-28

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

  15. Effect of a new carbon dioxide laser treatment on dissolution profiles of dental enamel

    NASA Astrophysics Data System (ADS)

    Featherstone, John D. B.; Le, Charles Q.; Fried, Daniel

    2003-06-01

    Previous studies have shown that pretreatment of dental enamel by specific carbon dioxide laser conditions inhibited subsequent acid dissolution of the enamel surface. The aim of the present study was to examine the dissolution profiles following irradiation by a new short pulse carbon dioxide laser treatment. Bovine enamel blocks were irradiated at 9.6 μm with a 5-8 μs or a 20-30 μs pulse duration laser using overlapping spots, and a range of fluences. Dissolution profiles were measured in an acetate buffer. Higher fluences produced rapid initial dissolution followed by a plateau with a low dissolution rate. For caries inhibition purposes the high solubility decomposition phases need to be avoided or removed.

  16. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Spectral and temporal characteristics of a laser plasma

    NASA Astrophysics Data System (ADS)

    Lipchak, A. I.; Solomonov, V. I.; Tel'nov, V. A.; Osipov, V. V.

    1995-04-01

    An experimental investigation was made of the spectral and temporal characteristics of a laser plasma formed by the interaction of a CO2 laser pulse with a target in atmospheric air. The results obtained indicate that the main role in the process of filling the excited states in a laser plasma is played by a recombination cascade and that both atoms and molecules of the atmospheric gases are excited. The result also show that a laser plasma can be used in spectroscopic analysis of multicomponent samples. The solution of the thermophysical problem of heating of a target by laser radiation supports the existing ideas on the process of formation of a plasma near the target surface in air.

  17. Infrared Pulse-laser Long-path Absorption Measurement of Carbon Dioxide Using a Raman-shifted Dye Laser

    NASA Technical Reports Server (NTRS)

    Minato, Atsushi; Sugimoto, Nobuo; Sasano, Yasuhiro

    1992-01-01

    A pulsed laser source is effective in infrared laser long-path absorption measurements when the optical path length is very long or the reflection from a hard target is utilized, because higher signal-to-noise ratio is obtained in the detection of weak return signals. We have investigated the performance of a pulse-laser long-path absorption system using a hydrogen Raman shifter and a tunable dye laser pumped by a Nd:YAG laser, which generates second Stokes radiation in the 2-micron region.

  18. Resonance transition radiation X-ray laser

    NASA Technical Reports Server (NTRS)

    Reid, Max B.; Piestrup, Melvin A.

    1991-01-01

    A free electron laser is proposed using a periodic dielectric and helical magnetic field. Periodic synchronism between the electrons and the optical wave is obtained at the period of the dielectric and not at the period of the helical magnetic field. The synchronism condition and the gain of the new device are derived. The effects on the gain from dephasing and beam expansion due to elastic scattering of the electrons in the periodic medium are included in the gain calculation. Examples of the resonance transition radiation laser and klystron are given. Operation at photon energies between 2.5 and 3.5 keV with net gain up to 12 percent is feasible using high electron-beam energies of 3 and 5 GeV. Moderate (300-MeV) beam energy allows operation between 80 to 110 eV with up to 57 percent net gain using a klystron design. In both cases, rapid foil heating may limit operation to a single electron-beam pulse.

  19. INTERACTION OF LASER RADIATION WITH MATTER: Collisionless absorption of intense laser radiation in nanoplasma

    NASA Astrophysics Data System (ADS)

    Zaretsky, D. F.; Korneev, Philipp A.; Popruzhenko, Sergei V.

    2007-06-01

    The rate of linear collisionless absorption of an electromagnetic radiation in a nanoplasma — classical electron gas localised in a heated ionised nanosystem (thin film or cluster) irradiated by an intense femtosecond laser pulse — is calculated. The absorption is caused by the inelastic electron scattering from the self-consistent potential of the system in the presence of a laser field. The effect proves to be appreciable because of a small size of the systems. General expressions are obtained for the absorption rate as a function of the parameters of the single-particle self-consistent potential and electron distribution function in the regime linear in field. For the simplest cases, where the self-consistent field is created by an infinitely deep well or an infinite charged plane, closed analytic expressions are obtained for the absorption rate. Estimates presented in the paper demonstrate that, over a wide range of the parameters of laser pulses and nanostructures, the collisionless mechanism of heating electron subsystem can be dominant. The possibility of experimental observation of the collisionless absorption of intense laser radiation in nanoplasma is also discussed.

  20. Directional radiation properties of industrial refractories of zirconium dioxide

    SciTech Connect

    Zapechnikov, V.N.; Pushkin, V.T.; Zen'kovskii, A.G.

    1986-09-01

    This paper uses magnesium oxide and sodium chloride as the standards in investigation of radiant properties of zirconium dioxide. The first was used in the 0.75-2.5 um wavelength range and the second in the 2.50-10 um range. The chemical composition of the dense material was 91.14 wt. % ZrO/sub 2/, 6 CaO and 0.9 SiO/sub 2/ and of the porous 89.61 ZrO, 7.95 CaO, and 0.36 SiO/sub 2/. In addition to the characteristics of spectral reflection for engineering practice an important value is the spatial distribution of the energy reflected from the real surface of a material. The dense refractory has a directional character of reflection.

  1. Carbon dioxide laser absorption spectra of toxic industrial compounds.

    PubMed

    Loper, G L; Sasaki, G R; Stamps, M A

    1982-05-01

    CO(2) laser absorption cross-section data are reported for acrolein, styrene, ethyl acrylate, trichloroethylene, vinyl bromide, and vinylidene chloride. These data indicate that sub parts per billion level, interference-free detection limits should be possible for these compounds by the CO(2) laser photoacoustic technique. Photoacoustic detectabilities below 40 ppb should be possible for these compounds in the presence of ambient air concentrations of water vapor and other anticipated interferences. These compounds are also found not to be important interferences in the detection of toxic hydrazine-based rocket fuels by CO(2) laser spectroscopic techniques.

  2. Intense terahertz radiation from relativistic laser-plasma interactions

    NASA Astrophysics Data System (ADS)

    Liao, G. Q.; Li, Y. T.; Li, C.; Liu, H.; Zhang, Y. H.; Jiang, W. M.; Yuan, X. H.; Nilsen, J.; Ozaki, T.; Wang, W. M.; Sheng, Z. M.; Neely, D.; McKenna, P.; Zhang, J.

    2017-01-01

    The development of tabletop intense terahertz (THz) radiation sources is extremely important for THz science and applications. This paper presents our measurements of intense THz radiation from relativistic laser-plasma interactions under different experimental conditions. Several THz generation mechanisms have been proposed and investigated, including coherent transition radiation (CTR) emitted by fast electrons from the target rear surface, transient current radiation at the front of the target, and mode conversion from electron plasma waves (EPWs) to THz waves. The results indicate that relativistic laser plasma is a promising driver of intense THz radiation sources.

  3. Thermal Conductivity Measurement of Xe-Implanted Uranium Dioxide Thick Films using Multilayer Laser Flash Analysis

    SciTech Connect

    Nelson, Andrew T.

    2012-08-30

    The Fuel Cycle Research and Development program's Advanced Fuels campaign is currently pursuing use of ion beam assisted deposition to produce uranium dioxide thick films containing xenon in various morphologies. To date, this technique has provided materials of interest for validation of predictive fuel performance codes and to provide insight into the behavior of xenon and other fission gasses under extreme conditions. In addition to the structural data provided by such thick films, it may be possible to couple these materials with multilayer laser flash analysis in order to measure the impact of xenon on thermal transport in uranium dioxide. A number of substrate materials (single crystal silicon carbide, molybdenum, and quartz) containing uranium dioxide films ranging from one to eight microns in thickness were evaluated using multilayer laser flash analysis in order to provide recommendations on the most promising substrates and geometries for further investigation. In general, the uranium dioxide films grown to date using ion beam assisted deposition were all found too thin for accurate measurement. Of the substrates tested, molybdenum performed the best and looks to be the best candidate for further development. Results obtained within this study suggest that the technique does possess the necessary resolution for measurement of uranium dioxide thick films, provided the films are grown in excess of fifty microns. This requirement is congruent with the material needs when viewed from a fundamental standpoint, as this length scale of material is required to adequately sample grain boundaries and possible second phases present in ceramic nuclear fuel.

  4. Surgical Coagulator With Carbon Dioxide Laser For Gynecology

    NASA Astrophysics Data System (ADS)

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

    1987-10-01

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

  5. Carbon dioxide lasers. Citations from the NTIS data base

    NASA Astrophysics Data System (ADS)

    Cavagnaro, D. M.

    1980-10-01

    Citations on theory, design, operation, output and diagnostics of CO2 lasers are presented. Studies relating to excitation, frequency conversion, modulation, laser pumping, reaction kinetics, gas dynamics, and plasmas are included. The development and efficiency of optical components such as mirrors, resonators, tuning devices, infrared optical materials, amplifiers, and gratings are also discussed. This updated bibliography contains 214 citations, 70 of which are new entries to the previous edition.

  6. Corona Preionization Technique for Carbon Dioxide TEA Lasers.

    DTIC Science & Technology

    1982-11-30

    environment such as that projected for the M-1 tank. However, the most challenging requirement for this laser is long sealed- off operation (> 2 x 106...optimized laser performance and long sealed- off lifetime. Preionization is the necessary means of providing initiating elec- trons in the main electrode gap...gradient technique lends itself to long sealed- off lifetime for reasons which will be made clear later in this section. However, a complete understanding of

  7. TIR-1 carbon dioxide laser system for fusion

    SciTech Connect

    Adamovich, V.A.; Anisimov, V.N.; Afonin, E.A.; Baranov, V.Y.; Borzenko, V.L.; Kozochkin, S.M.; Malyuta, D.D.; Satov, Y.A.; Sebrant, A.Y.; Smakovski, Y.B.; Starostin, A.N.; Streltzov, A.P.; Petryakov, V.M.; Chalkin, S.F.

    1980-03-15

    During recent years pulsed CO/sub 2/ lasers for fusion research have been under construction in the I. V. Kurchatov Institute of Atomic Energy and the D. V. Efremov Electro-Physical Apparatus Institute. Efforts are being concentrated at present on two approaches: (1) microsecond laser pulse plasma heating in solenoids and theta pinches (UTRO system) and (2) nanosecond CO/sub 2/ laser utilization for inertial confinement fusion. The TIR-1 system was created to develop nanosecond CO/sub 2/ laser technology and to study laser--target interaction at 10 ..mu..m. This system is designed to deliver approx.1-kJ energy in one beam of approx.1-nsec duration. The TIR-1 system consists of an oscillator--preamplifier system that produces an approx.1-nsec laser pulse with an energy contrast ratio of approx.10/sup 6/, a large-aperture (30 x 30-cm/sup 2/) triple-pass amplifier capable of providing approx. =1 kJ in a 1-nsec pulse, a target chamber with diagnostic equipment, and associated engineering systems.

  8. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Laser plume spectroscopy. 1. Graphite target

    NASA Astrophysics Data System (ADS)

    Osipov, V. V.; Solomonov, V. I.; Platonov, V. V.; Snigireva, O. A.; Ivanov, M. G.; Lisenkov, V. V.

    2005-05-01

    Spectral and kinetic characteristics of a plume formed in the vicinity of a graphite target exposed to radiation from a pulsed CO2 laser at 10.6 μm with a peak power of 9 kW (pulse energy 1.69 J, pulse duration 330 μs at the 0.1 level) in air are studied at room temperature. It is shown that the plume propagating at a right angle to the target surface and at an angle of 45° to the laser radiation is a nonequilibrium gas plasma flow at a temperature of the order of 10 kK; its shape and size are determined by the shape and power of the laser pulse. Emission of C+ ions and C2 molecules is excited in the plume. The temperature and emission are sustained by the energy of the exothermic reaction of association of carbon atoms and the vibrationally excited molecules formed in it.

  9. Carbon dioxide laser use for certain diseases of the toenails.

    PubMed

    Rothermel, E; Apfelberg, D B

    1987-10-01

    The CO2 laser has facilitated the treatment of many toenail conditions. Satisfactory wound healing and cure rates have been equivalent to current standards of treatment. Pain was markedly diminished as compared with pain in traditional methods of treatment, and time until comfortable ambulation was dramatically shortened. Healing times were consistent with those in other methods of treatment. The protocol for CO2 treatment of nail conditions has been thoroughly described. Evaluation of 50 patients after 4 years from treatment date is tabulated. The CO2 laser must be strongly considered as a treatment modality for toenail pathology. Because of markedly reduced pain, minimal disability, and satisfactory long-term results, the laser is becoming a valuable treatment of choice for pathologic conditions of the nail.

  10. Selective removal of dental composite using a rapidly scanned carbon dioxide laser

    NASA Astrophysics Data System (ADS)

    Chan, Kenneth H.; Fried, Daniel

    2011-03-01

    Dental restorative materials are color matched to the tooth and are difficult to remove by mechanical means without excessive removal or damage to peripheral enamel and dentin. Lasers are ideally suited for selective ablation to minimize healthy tissue loss when replacing existing restorations, sealants or removing composite adhesives such as residual composite left after debonding orthodontic brackets. In this study a carbon dioxide laser operating at high laser pulse repetition rates integrated with a galvanometer based scanner was used to selectively remove composite from tooth surfaces. A diode array spectrometer was used to measure the plume emission after each laser pulse and determine if the ablated material was tooth mineral or composite. The composite was placed on tooth buccal and occlusal surfaces and the carbon dioxide laser was scanned across the surface to selectively remove the composite without excessive damage to the underlying sound enamel. The residual composite and the damage to the underlying enamel was evaluated using optical microscopy. The laser was able to rapidly remove the composites rapidly from both surfaces with minimal damage to the underlying sound enamel.

  11. Laser therapy for the treatment of Hailey-Hailey disease: a systematic review with focus on carbon dioxide laser resurfacing.

    PubMed

    Falto-Aizpurua, L A; Griffith, R D; Yazdani Abyaneh, M A; Nouri, K

    2015-06-01

    Benign familial chronic pemphigus, or Hailey-Hailey disease (HHD), is a recurrent bullous dermatitis that tends to have a chronic course with frequent relapses. Long-term treatment options include surgery with skin grafting or dermabrasion. Both are highly invasive and carry significant risks and complications. More recently, 'laser-abrasion' has been described as a less invasive option with a better side-effect profile. In this article, we systematically review the safety and efficacy of carbon dioxide laser therapy as a long-term treatment option for HHD, as well as provide a review of other lasers that have been reported with this goal. A total of 23 patients who had been treated with a carbon dioxide laser were identified. After treatment, 10 patients (43%) had had no recurrence, 10 (43%) had greater than 50% improvement, 2 (8%) had less than 50% improvement and 1 (4%) patient had no improvement at all (follow-up period ranged from 4 to 144 months). Laser parameter variability was wide and adverse effects were minimal, including dyspigmentation and scarring. Reviewed evidence indicates this therapy offers a safe, effective treatment alternative for HHD with minimal risk of side-effects. Larger, well-designed studies are necessary to determine the optimal treatment parameters.

  12. Terahertz plasmonic laser radiating in an ultra-narrow beam

    SciTech Connect

    Wu, Chongzhao; Khanal, Sudeep; Reno, John L.; Kumar, Sushil

    2016-07-07

    Plasmonic lasers (spasers) generate coherent surface plasmon polaritons (SPPs) and could be realized at subwavelength dimensions in metallic cavities for applications in nanoscale optics. Plasmonic cavities are also utilized for terahertz quantum-cascade lasers (QCLs), which are the brightest available solid-state sources of terahertz radiation. A long standing challenge for spasers that are utilized as nanoscale sources of radiation, is their poor coupling to the far-field radiation. Unlike conventional lasers that could produce directional beams, spasers have highly divergent radiation patterns due to their subwavelength apertures. Here, we theoretically and experimentally demonstrate a new technique for implementing distributed feedback (DFB) that is distinct from any other previously utilized DFB schemes for semiconductor lasers. The so-termed antenna-feedback scheme leads to single-mode operation in plasmonic lasers, couples the resonant SPP mode to a highly directional far-field radiation pattern, and integrates hybrid SPPs in surrounding medium into the operation of the DFB lasers. Experimentally, the antenna-feedback method, which does not require the phase matching to a well-defined effective index, is implemented for terahertz QCLs, and single-mode terahertz QCLs with a beam divergence as small as 4°×4° are demonstrated, which is the narrowest beam reported for any terahertz QCL to date. Moreover, in contrast to a negligible radiative field in conventional photonic band-edge lasers, in which the periodicity follows the integer multiple of half-wavelengths inside the active medium, antenna-feedback breaks this integer limit for the first time and enhances the radiative field of the lasing mode. Terahertz lasers with narrow-beam emission will find applications for integrated as well as standoff terahertz spectroscopy and sensing. Furthermore, the antenna-feedback scheme is generally applicable to any plasmonic laser with a Fabry–Perot cavity

  13. Terahertz plasmonic laser radiating in an ultra-narrow beam

    DOE PAGES

    Wu, Chongzhao; Khanal, Sudeep; Reno, John L.; ...

    2016-07-07

    Plasmonic lasers (spasers) generate coherent surface plasmon polaritons (SPPs) and could be realized at subwavelength dimensions in metallic cavities for applications in nanoscale optics. Plasmonic cavities are also utilized for terahertz quantum-cascade lasers (QCLs), which are the brightest available solid-state sources of terahertz radiation. A long standing challenge for spasers that are utilized as nanoscale sources of radiation, is their poor coupling to the far-field radiation. Unlike conventional lasers that could produce directional beams, spasers have highly divergent radiation patterns due to their subwavelength apertures. Here, we theoretically and experimentally demonstrate a new technique for implementing distributed feedback (DFB) thatmore » is distinct from any other previously utilized DFB schemes for semiconductor lasers. The so-termed antenna-feedback scheme leads to single-mode operation in plasmonic lasers, couples the resonant SPP mode to a highly directional far-field radiation pattern, and integrates hybrid SPPs in surrounding medium into the operation of the DFB lasers. Experimentally, the antenna-feedback method, which does not require the phase matching to a well-defined effective index, is implemented for terahertz QCLs, and single-mode terahertz QCLs with a beam divergence as small as 4°×4° are demonstrated, which is the narrowest beam reported for any terahertz QCL to date. Moreover, in contrast to a negligible radiative field in conventional photonic band-edge lasers, in which the periodicity follows the integer multiple of half-wavelengths inside the active medium, antenna-feedback breaks this integer limit for the first time and enhances the radiative field of the lasing mode. Terahertz lasers with narrow-beam emission will find applications for integrated as well as standoff terahertz spectroscopy and sensing. Furthermore, the antenna-feedback scheme is generally applicable to any plasmonic laser with a Fabry–Perot cavity

  14. Laser radiation propagation in the hard and soft dental tissues

    NASA Astrophysics Data System (ADS)

    Dostalova, Tatjana; Jelinkova, Helena; Sulc, Jan; Cerny, Pavel; Nemec, Michal; Cech, Miroslav; Miyagi, Mitsunobu

    2000-03-01

    The objective of this study was to compare the penetration effect of the near and mid-infrared laser radiation. For this reason the Er:YAG, Nd:YAG, and alexandrite laser systems were used in the experiments. The spread of the laser radiation energy in the hard dental tissue surrounding the root canal was evaluated and the possible bactericidal effect of these various laser wavelengths was analyzed. During the measurements, three experimental arrangements were used. The energy transport through the tooth tissue was observed for the frontal and side experimental layout. It was demonstrated that due to the absorption in the hydroxyapatite and water content in the dentin, the Er:YAG laser radiation is fully, and the Nd:YAG is partly absorbed in the root canal's wall. On the other hand, it was proved that the alexandrite laser radiation spreads through the canal system space and leaks into the surrounding tooth tissues. All laser radiation can be efficiently used for killing dental bacteria but the spreading of their radiation in the tooth tissues is different.

  15. Selective removal of demineralization using near infrared cross polarization reflectance and a carbon dioxide laser

    NASA Astrophysics Data System (ADS)

    Chan, Kenneth H.; Fried, Daniel

    2012-01-01

    Lasers can ablate/remove tissue in a non-contact mode of operation and a pulsed laser beam does not interfere with the ability to image the tooth surface, therefore lasers are ideally suited for integration with imaging devices for image-guided ablation. Laser energy can be rapidly and efficiently delivered to tooth surfaces using a digitally controlled laser beam scanning system for precise and selective laser ablation with minimal loss of healthy tissues. Under the appropriate irradiation conditions such laser energy can induce beneficial chemical and morphological changes in the walls of the drilled cavity that can increase resistance to further dental decay and produce surfaces with enhanced adhesive properties to restorative materials. Previous studies have shown that images acquired using near-IR transillumination, optical coherence tomography and fluorescence can be used to guide the laser for selective removal of demineralized enamel. Recent studies have shown that NIR reflectance measurements at 1470-nm can be used to obtain images of enamel demineralization with very high contrast. The purpose of this study was to demonstrate that image guided ablation of occlusal lesions can be successfully carried out using a NIR reflectance imaging system coupled with a carbon dioxide laser operating at 9.3-μm with high pulse repetition rates.

  16. Fractionated ablative carbon dioxide laser for the treatment of rhinophyma.

    PubMed

    Serowka, Kathryn L; Saedi, Nazanin; Dover, Jeffrey S; Zachary, Christopher B

    2014-01-01

    Rhinophyma is a progressive and disfiguring proliferative disorder of the nose, which is related to chronic rosacea. Many different treatment modalities have been utilized both alone and in combination including: loop cautery, CO2 laser, argon laser, dermabrasion, cryotherapy, radiotherapy, full-thickness excision, skin graft, flap reconstruction, and cold scalpel. CO2 resurfacing has been considered first line therapy but is often associated with a shiny, scarred appearance, with patulous pores, and with loss of pigmentation. We report a technique using aggressive parameters with the fractionated ablative CO2 laser, resulting in improvement of appearance with very few complications. Five patients who presented with rhinophyma of varying degrees were treated with a series of fractional ablative CO2 laser treatments (Fraxel re:Pair, Solta Medical, Hayward, CA). These patients were treated with settings of up to 70 mJ, 70% density and 16-18 passes. All patients received HSV prophylaxis using either acyclovir 400 mg TID or valacyclovir 500 mg BID. Patients were rendered anesthetic by 1% lidocaine and epinephrine regional perinasal nerve block. All of the patients tolerated the procedure well with reepithelialization at days 4-7 and self-limited edema and erythema. Patients with relatively early to moderate signs of rhinophyma proved optimal candidates for this treatment. There were no adverse events. Patients and physicians noted significant improvement and reduction in the rhinophyma without the typical scarring noted with most other treatments. Rhinophyma treated with fractionated ablative CO2 laser using relatively aggressive parameters achieved good cosmetic outcomes in this group of early to moderate cases of rhinophyma, while still retaining the benefits of a fractionated treatment such as faster healing times and fewer adverse events. © 2013 Wiley Periodicals, Inc.

  17. Radiative heat transport instability in a laser produced inhomogeneous plasma

    SciTech Connect

    Bychenkov, V. Yu.; Rozmus, W.

    2015-08-15

    A laser produced high-Z plasma in which an energy balance is achieved due to radiation emission and radiative heat transfer supports ion acoustic instability. A linear dispersion relation is derived, and instability is compared to the radiation cooling instability [R. G. Evans, Plasma Phys. Controlled Fusion 27, 751 (1985)]. Under conditions of indirect drive fusion experiments, the driving term for the instability is the radiative heat flux and, in particular, the density dependence of the radiative heat conductivity. A specific example of thermal Bremsstrahlung radiation source has been considered. This instability may lead to plasma jet formation and anisotropic x-ray generation, thus affecting inertial confinement fusion related experiments.

  18. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Properties of the interaction of laser radiation with a gaseous dust medium

    NASA Astrophysics Data System (ADS)

    Glova, A. F.; Lysikov, A. Yu; Zverev, M. M.

    2009-06-01

    It is found that upon irradiation of a mixture of the atmospheric air and carbon particles of size 30-300 μm at a concentration of ~102 cm-3 by a cw CO2 laser, the active combustion of particles in the mixture appears when the radiation intensity in the focal region achieves ~103 W cm-2. The dependences of the threshold radiation intensity for the evaporation of particles on their radius are obtained for a gaseous dust medium in the form of a free vertical jet of spherical aluminium and carbon microparticles in nitrogen. It is shown that particles of size ~10 μm can be completely evaporated in a focused cw laser beam of power ~102 W.

  19. Direct determination of carbon dioxide in aqueous solution using mid-infrared quantum cascade lasers.

    PubMed

    Schaden, S; Haberkorn, M; Frank, J; Baena, J R; Lendl, B

    2004-06-01

    A method for the direct determination of carbon dioxide in aqueous solutions using a room-temperature mid-infrared (MIR) quantum cascade laser at 2330 cm(-1) is reported. The absorption values of different carbon dioxide concentrations were measured in a 119 microm CaF2 flow-through cell. An optical system made of parabolic mirrors was used to probe the flow cell and to focus the laser beam on the mercury cadmium telluride (MCT) detector. Aqueous carbon dioxide standards were prepared by feeding different mixtures of gaseous N2 and CO2 through wash bottles at controlled temperature. The concentration of the dissolved CO2 was calculated according to Henry's law, taking into account the temperature and the partial pressure of CO2. The carbon dioxide standards were connected via a selection valve to a peristaltic pump for subsequent, automated measurement in the flow-through cell. A calibration curve was obtained in the range of 0.338 to 1.350 g/L CO2 with a standard deviation of the method sxo equal to 19.4 mg/L CO2. The limit of detection was calculated as three times the baseline noise over time and was determined to be 39 mg/L.

  20. [Monitoring the flux of carbon dioxide gas with tunable diode laser absorption spectroscopy].

    PubMed

    Song, Xue-Mei; Liu, Jian-Guo; Zhang, Yu-Jun; Zeng, Zong-Yong; He, Ying; Cui, Yi-Ben; Chen, Yin; Tian, Yong-Zhi; Zhang, Liang

    2011-01-01

    The greenhouse effect exacerbated by the increase of Carbon-containing gases is the more important causes of the climate change, It is very meaningful to the large-scale flux of carbon dioxide detection for the estimate the contributions of the main greenhouse gases in the atmosphere of various errestrial eco-systems. Tunable diode laser absorption spectroscopy (TDLAS) is a highly sensitive, highly selective and fast time response trace gas detection technique. In the present paper, the authors used a DFB laser was used as the light source, and by employing wavelength modulation method, and measuring the second harmonic signal of one absorption line near 1.573 microm of carbon dioxide molecule, the authors built a system for online monitoring of carbon dioxide concentration within the optical path of more than 700 meters at different heights. Combined with Alonzo Mourning -Obukhov length and characteristic velocity detected by large aperture scintillometer, the flux of carbon dioxide gas within one day calculated by the formula is within--1.5-2.5, breaking through the phenomenon of only providing the flux of trace gases near the ground at present, makking the measurement of trace gas fluxes within a large area possible.

  1. Plasma lasers (a strong source of coherent radiation in astrophysics)

    NASA Technical Reports Server (NTRS)

    Papadopoulos, K.

    1981-01-01

    The generation of electromagnetic radiation from the free energy available in electron streams is discussed. The fundamental principles involved in a particular class of coherent plasma radiation sources, i.e., plasma lasers, are reviewed, focusing on three wave coupling, nonlinear parametric instabilities, and negative energy waves. The simplest case of plasma lasers, that of an unmagnetized plasma containing a finite level of density fluctuations and electrons streaming with respect to the ions, is dealt with. A much more complicated application of plasma lasers to the case of auroral kilometric radiation is then examined. The concept of free electron lasers, including the role of relativistic scattering, is elucidated. Important problems involving the escape of the excited radiation from its generation region, effects due to plasma shielding and nonlinear limits, are brought out.

  2. Plume attenuation of laser radiation during high power fiber laser welding

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

    The results of an in-situ plume-laser interaction measurement during welding of mild steel with a 5 kW ytterbium fiber laser are reported. A measurement of the attenuation of probe laser beam passing through the plume has allowed to estimate the plume characteristics like the size of the extinction area and the spatial distribution of the extinction coefficient. The power loss of the fiber laser radiation propagating through the whole plume length was calculated. Together with a measured temporal characteristics of extinction the result indicates a significant decreasing of the laser radiation stability, which can lead to the formation of the macroscopic welding defects.

  3. Radiation Damage on Multiple Length Scales in Uranium Dioxide

    NASA Astrophysics Data System (ADS)

    Gupta, Mahima

    Radiation damage in UO2 has been well studied but there exists little correlation between point defect accumulation, lattice structure changes and microstructure. This is partly because irradiated nuclear fuel is highly radioactive and its defect chemistry is extremely complicated resulting from fission of the material and consequent fission products being embedded in the fuel matrix [Olander1976]. To adequately study the evolution of defects from point defects through to microstructure features, the resulting defects have to be intentionally simplified for characterization. Ion accelerators have the unique capability of creating simple microstructure features using specific ions, without the added complication of fission and neutron activation from nuclear reactors. As an example, H+ ions have been used to create (only) a distribution of dislocations that were studied using various techniques. The ability to tune the energy or type of the ion to achieve desirable implantation depth and ideally simple microstructure renders it a lucrative instrument for this type of analysis. X-ray diffraction (XRD) studies and transmission electron microscopy (TEM) have been utilized to study extended structure changes and microstructure evolution. Ion beam irradiations create displacements and displacement networks, voids, surface fracturing, gas bubbles and several other microstructure changes to model nuclear reactor damage [Noris1972]. Using an ion accelerator, it has been possible to isolate these radiation induced defects and study their subsequent evolution with increasing dose. Insofar, since all of the phenomena caused by radiation damage originate from point defects, the elucidation of radiation effects on the atomic scale is crucial. This is rendered complicated due to aperiodic irradiation defects. This lack of periodicity renders standard approaches, such as TEM and XRD ineffective, as these methods probe average structure over tens of Angstroms. Therefore, techniques

  4. JPL Carbon Dioxide Laser Absorption Spectrometer Data Processing Results for the 2010 Flight Campaign

    NASA Technical Reports Server (NTRS)

    Jacob, Joseph C.; Spiers, Gary D.; Menzie, Robert T.; Christensen, Lance E.

    2011-01-01

    As a precursor to and validation of the core technology necessary for NASA's Active Sensing of CO2 Emissions over Nights, Days,and Seasons (ASCENDS) mission, we flew JPL's Carbon Dioxide Laser Absorption Spectrometer (CO2LAS) in a campaign of five flights onboard NASA's DC-8 Airborne Laboratory in July 2010. This is the latest in a series of annual flight campaigns that began in 2006, and our first on the DC-8 aircraft.

  5. Design of catalytic monoliths for closed-cycle carbon dioxide lasers

    NASA Technical Reports Server (NTRS)

    Herz, Richard K.

    1988-01-01

    A computer program was written that allows the design of catalytic monoliths for closed-cycle carbon dioxide lasers. Using design parameters obtained from workers at NASA Langley Research Center and from the literature, several specific monoliths were designed and the results were communicated to the research group working on this project at Langley. Two oral presentations were made at NASA-sponsored workshops - at Langley in January 1988 and in Gainesville, Florida in May 1988.

  6. Carbon Dioxide Laser Microsurgical Median Glossotomy for Resection of Lingual Dermoid Cysts

    PubMed Central

    Corvers, Kristien; Hens, Greet; Meulemans, Jeroen; Delaere, Pierre; Hermans, Robert; Vander Poorten, Vincent

    2016-01-01

    Dermoid cysts are epithelial-lined cavities with skin adnexae in the capsule. Only 7% is present in the head and neck. Between 2004 and 2013, four patients with a lingual dermoid cyst underwent a microsurgical carbon dioxide laser resection via a median sagittal glossotomy approach. This approach is an elegant technique combining superior visualization, hemostasis, and little postoperative edema with good wound healing, allowing for perfect function preservation of the tongue. PMID:27504448

  7. Photodissociation of nitrogen dioxide by pulsed laser light at 6943 A.

    NASA Technical Reports Server (NTRS)

    Gerstmayr, J. W.; Harteck, P.; Reeves, R. R.

    1972-01-01

    Nitrogen dioxide was photodissociated using a pulsed ruby laser at 6943 A. The energy of a single photon at this wavelength was equivalent to only 57% of the dissociation energy. The mechanism proposed to account for the results was the consecutive absorption of two photons, the first resulting in a short-lived excited state. The second photon is then absorbed by the excited species resulting in dissociation.

  8. Use of a carbon dioxide laser to treat ceruminous gland hyperplasia in a cat.

    PubMed

    Corriveau, Lorraine Ann

    2012-06-01

    This case report describes the skin condition ceruminous gland hyperplasia of the ears of a cat. The diagnosis was made through histopathology. Treatment consisted of carbon dioxide laser ablation of the cystic structures and postoperative care associated with the surgery, as well as a hydrolyzed protein diet, weekly ear cleaning and intermittent topical corticosteroid drops in the ears to minimize the reoccurrence of the cysts.

  9. Multilevel radiative thermal memory realized by the hysteretic metal-insulator transition of vanadium dioxide

    SciTech Connect

    Ito, Kota Nishikawa, Kazutaka; Iizuka, Hideo

    2016-02-01

    Thermal information processing is attracting much interest as an analog of electronic computing. We experimentally demonstrated a radiative thermal memory utilizing a phase change material. The hysteretic metal-insulator transition of vanadium dioxide (VO{sub 2}) allows us to obtain a multilevel memory. We developed a Preisach model to explain the hysteretic radiative heat transfer between a VO{sub 2} film and a fused quartz substrate. The transient response of our memory predicted by the Preisach model agrees well with the measured response. Our multilevel thermal memory paves the way for thermal information processing as well as contactless thermal management.

  10. Multilevel radiative thermal memory realized by the hysteretic metal-insulator transition of vanadium dioxide

    NASA Astrophysics Data System (ADS)

    Ito, Kota; Nishikawa, Kazutaka; Iizuka, Hideo

    2016-02-01

    Thermal information processing is attracting much interest as an analog of electronic computing. We experimentally demonstrated a radiative thermal memory utilizing a phase change material. The hysteretic metal-insulator transition of vanadium dioxide (VO2) allows us to obtain a multilevel memory. We developed a Preisach model to explain the hysteretic radiative heat transfer between a VO2 film and a fused quartz substrate. The transient response of our memory predicted by the Preisach model agrees well with the measured response. Our multilevel thermal memory paves the way for thermal information processing as well as contactless thermal management.

  11. Practical challenges for radiation-balanced lasers (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Bowman, Steven R.

    2017-02-01

    Radiation Balanced Lasers (RBL) use cooling from spontaneous emission to offset waste heat generation. This technique offers the potential for very high power operation without thermo-optic distortions or damage. Nevertheless establishing and maintaining radiation balance poses interesting problems for the laser designer. An analysis of RBL's sensitivity to material losses, intensity variation, and temperature will be presented. This comparison of simulations and experiments is intended to assist in the design of future high power systems.

  12. Carbon dioxide laser enucleation of polypoid vocal cords.

    PubMed

    Yates, A; Dedo, H H

    1984-06-01

    Polypoid vocal cords have routinely been treated by endoscopic vocal cord stripping, often-times resulting in prolonged hoarseness postoperatively. Submucosal CO2 laser enucleation of the polypoid tissue, with preservation of a mucosal flap on the medial edge of the cord, has proved to be a valuable improvement. The surgical procedure is described and results are presented which suggest that voice quality is better earlier than is the case after vocal cord stripping.

  13. Carbon dioxide laser-induced combustion of extravasated intraocular silicone oil in the eyelid mimicking xanthelasma.

    PubMed

    Santaella, Ricardo M; Ng, John D; Wilson, David J

    2011-01-01

    A 48-year-old woman with a history of retinal detachment repair with vitrectomy, scleral buckling, and silicone oil with subsequent oil removal was referred for unilateral upper eyelid ptosis with edema and overlying skin changes simulating xanthelasma. During surgical excision, a white flare-like plume was noted when the carbon dioxide (CO2) laser was used to make the incisions. The pathology report confirmed silicone oil intrusion in the conjunctiva and upper eyelid. A postoperative in vitro experiment showed that silicone oil was readily ignited by the CO2 laser.

  14. Treatment of Facial Lesions of Multicentric Reticulohistiocytosis by Carbon Dioxide Laser

    PubMed Central

    Mahajan, Rashmi S; Shah, Aishani C.; Nagar, Amit; Freny, Bilimoria E

    2013-01-01

    The carbon dioxide (CO2) laser is a versatile tool that has applications in ablative lasing and caters to the needs of routine dermatological practice as well as the esthetic, cosmetic, and rejuvenation segments. We report a case of multicentric reticulohistiocytosis with cosmetically disfiguring confluent papules over the scalp, forehead, nasolabial folds, chin, and retroauricular region. We used CO2 laser in superpulse mode for ablating the lesions in three sittings. The lesions regressed completely and no recurrence was observed over a regular follow-up of 8 months. PMID:24163535

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

    PubMed

    Sosis, M B

    1995-08-01

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

  16. Dissociation phenomena in electron-beam sustained carbon dioxide lasers

    NASA Technical Reports Server (NTRS)

    Harris, Michael R.; Willetts, David V.

    1990-01-01

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

  17. Dissociation phenomena in electron-beam sustained carbon dioxide lasers

    NASA Astrophysics Data System (ADS)

    Harris, Michael R.; Willetts, David V.

    1990-06-01

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

  18. Novel radiator for carbon dioxide absorbents in low-flow anesthesia.

    PubMed

    Hirabayashi, Go; Mitsui, Takanori; Kakinuma, Takayasu; Ogihara, Yukihiko; Matsumoto, Shohei; Isshiki, Atsushi; Yasuo, Watanabe

    2003-01-01

    During long-term low-flow sevoflurane anesthesia, dew formation and the generation of compound A are increased in the anesthesia circuit because of elevated soda lime temperature. The object of this study was to develop a novel radiator for carbon dioxide absorbents used for long durations of low-flow sevoflurane anesthesia. Eleven female swine were divided into two groups comprising a "radiator" group (n = 5) that used a novel radiator for carbon dioxide absorbents and a "control" group (n = 6) that used a conventional canister. Anesthesia was maintained with N2O, O2, and sevoflurane, and low-flow anesthesia was performed with fresh gas flow at 0.6 L/min for 12 hr. In the "control" group, the soda lime temperature reached more than 40 degrees C and soda lime dried up with severe dew formation in the inspiratory valve. In the "radiator" group, the temperature of soda lime stayed at 30 degrees C, and the water content of soda lime was retained with no dew formation in the inspiratory valve. In addition, compound A concentration was reduced. In conclusion, radiation of soda lime reduced the amounts of condensation formed and the concentration of compound A in the anesthetic circuit, and allowed long term low-flow anesthesia without equipment malfunction.

  19. Prophylaxis and treatment of acute radiation ulcers in rats with low-power infrared laser radiation

    NASA Astrophysics Data System (ADS)

    Kursova, Larisa V.; Kaplan, Michael A.; Nikitina, Rosa G.; Maligina, Antonina I.

    1999-12-01

    Exposure of radiation ulcers in rats to low-power infrared laser radiation (LPLR) (wavelength--890 nm, pulse power--6 W, frequency--150 and 300 Hz, irradiation time--10 min) noticeably accelerates their healing, reduces exudative processes, increases number of specialized cells in wound. Application of LPLR prior to radiation damage decreases ulcer dimensions.

  20. [Study of remote sensing the flux of carbon dioxide gas with tunable diode laser absorption spectroscopy].

    PubMed

    Song, Xue-mei; Liu, Jian-guo; Zhang, Yu-jun; Lu, Yi-huai; Zeng, Zong-yong; He, Ying; Cui, Yi-ben; Tian, Yong-zhi; Tian, Lin

    2011-03-01

    Tunable diode laser absorption spectroscopy (TDLAS) technique is a new method to detect trace gas qualitatively or quantificationally based on the scan characteristic of the diode laser to obtain the absorption spectra in the characteristic absorption region. TDLAS is a highly sensitive, highly selective and fast time response trace gas detection technique. In the present paper, a DFB laser at room temperature was used as the light source, wavelength modulation method was employed, and the second harmonic signal of one absorption line near 1.578 microm of carbon dioxide molecule was measured. A system was built for online monitoring of carbon dioxide concentration within the optical path of more than 700 meters at different heights. Combined with Alonzo Mourning-Obukhov length and characteristic velocity detected by large aperture scintillometer, the flux of carbon dioxide gas calculated by the experiential formula is within -60-60 mg x m(-2) x s(-1). The comparison of the datea detected by TDLAS system and the eddy covariance showed that the change of the data detected by TDLAS had a similar trend to that detected by the eddy covariance, and the best results can be produced by this method, breaking through the phenomenon of only providing the flux of trace gases near the ground at present, and making the measurement of trace gas fluxes within a large area possible.

  1. Laser radiation and motility patterns of human sperm

    SciTech Connect

    Lenzi, A.; Claroni, F.; Gandini, L.; Lombardo, F.; Barbieri, C.; Lino, A.; Dondero, F. )

    1989-01-01

    Human sperm were exposed in vitro to laser radiation. An increase in progressive sperm motility was associated with a faster rate of sperm ATP consumption. Computer-assisted analysis of sperm motility confirmed the positive effect of laser irradiation on velocity and linearity of sperm.

  2. A blackbody radiation-pumped CO2 laser experiment

    NASA Astrophysics Data System (ADS)

    Christiansen, W. H.; Insuik, R. J.; Deyoung, R. J.

    1982-09-01

    Thermal radiation from a high temperature oven was used as an optical pump to achieve lasing from CO2 mixtures. Laser output as a function of blackbody temperature and gas conditions is described. This achievement represents the first blackbody cavity pumped laser and has potential for solar pumping.

  3. Adhesion studies on dental enamel surfaces irradiated by a rapidly scanned carbon dioxide laser

    NASA Astrophysics Data System (ADS)

    Chang, Kwang K.; Staninec, Michal; Chan, Kenneth H.; Fried, Daniel

    2011-03-01

    In this study, we investigated the influence of different laser scanning patterns on the adhesive strength of laser irradiated enamel surfaces both with and without post ablation acid etching. Previous studies of dental enamel surfaces ablated by a rapidly scanned carbon dioxide laser indicated that the highly uniform smooth surfaces produced by the scanned laser beam yielded low bond strength and acid etching was required in order to attain a high bond strength. However, since the enamel surface after ablation by CO2 lasers is more resistant to acid dissolution it is desirable to avoid acid etching before bonding. The overlap between adjacent laser spots was varied to modify the effective surface roughness. In addition, small retention holes were drilled at higher laser intensity with varying spacing to increase the adhesive strength without acid etching. Varying the degree of overlap between adjacent laser spots did not significantly influence the bond strength with post ablation acid etching. The bond strength was significantly higher without acid etching with retention holes spaced 250-μm apart.

  4. Adhesion studies on dental enamel surfaces irradiated by a rapidly scanned carbon dioxide laser.

    PubMed

    Chang, Kwang K; Staninec, Michal; Chan, Kenneth H; Fried, Daniel

    2011-01-01

    In this study, we investigated the influence of different laser scanning patterns on the adhesive strength of laser irradiated enamel surfaces both with and without post ablation acid etching. Previous studies of dental enamel surfaces ablated by a rapidly scanned carbon dioxide laser indicated that the highly uniform smooth surfaces produced by the scanned laser beam yielded low bond strength and acid etching was required in order to attain a high bond strength. However, since the enamel surface after ablation by CO(2) lasers is more resistant to acid dissolution it is desirable to avoid acid etching before bonding. The overlap between adjacent laser spots was varied to modify the effective surface roughness. In addition, small retention holes were drilled at higher laser intensity with varying spacing to increase the adhesive strength without acid etching. Varying the degree of overlap between adjacent laser spots did not significantly influence the bond strength with post ablation acid etching. The bond strength was significantly higher without acid etching with retention holes spaced 250-µm apart.

  5. CONTROL OF RADIATION PARAMETERS Radiation phase locking in an array of globally coupled fibre lasers

    NASA Astrophysics Data System (ADS)

    Vysotskii, D. V.; Elkin, N. N.; Napartovich, A. P.

    2010-12-01

    A model of an array of globally coupled fibre lasers, with the same fraction of the total output beam returned to each laser, is considered. The basic element of the model is a single laser controlled by an external signal. The output power of each laser in the array is found as a function of small-signal gain and frequency detuning. The maximum efficiency of phase locking and minimum fraction of output radiation that is necessary to form a feedback are calculated as functions of the number of lasers in the array. It is shown that gain saturation increases the efficiency of coherent beam summation in arrays containing up to 20 lasers.

  6. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Feasibility of investigation of optical breakdown statistics using multifrequency lasers

    NASA Astrophysics Data System (ADS)

    Ulanov, S. F.

    1990-06-01

    A method proposed for investigating the statistics of bulk optical breakdown relies on multifrequency lasers, which eliminates the influence of the laser radiation intensity statistics. The method is based on preliminary recording of the peak intensity statistics of multifrequency laser radiation pulses at the caustic using the optical breakdown threshold of K8 glass. The probability density distribution function was obtained at the focus for the peak intensities of the radiation pulses of a multifrequency laser. This method may be used to study the self-interaction under conditions of bulk optical breakdown of transparent dielectrics.

  7. Studies of new media radiation induced laser

    NASA Technical Reports Server (NTRS)

    Han, K. S.; Shiu, Y. J.; Raju, S. R.; Hwang, I. H.; Tabibi, B.

    1984-01-01

    Various lasants were investigated especially, 2-iodohepafluoropropane (i-C3F7I) for the direct solar pumped lasers. Optical pumping of iodine laser was achieved using a small flashlamp. Using i-C3F7I as a laser gain medium, threshold inversion density, small signal gain, and laser performance at the elevated temperature were measured. The experimental results and analysis are presented. The iodine laser kinetics of the C3F7I and IBr system were numerically simulated. The concept of a direct solar-pumped laser amplifier using (i-C3F7I) as the laser material was evaluated and several kinetic coefficients for i-C3F7I laser system were reexamined. The results are discussed.

  8. Mathematical modeling of a photovoltaic-laser energy converter for iodine laser radiation

    NASA Technical Reports Server (NTRS)

    Walker, Gilbert H.; Heinbockel, John H.

    1987-01-01

    Space-based laser power systems will require converters to change laser radiation into electricity. Vertical junction photovoltaic converters are promising devices for this use. A promising laser for the laser power station is the t-C4F9I laser which emits radiation at a wavelength of 1.315 microns. This paper describes the results of mathematical modeling of a photovoltaic-laser energy converter for use with this laser. The material for this photovoltaic converter is Ga(53)In(47)As which has a bandgap energy of 0.94 eV, slightly below the energy of the laser photons (0.943 eV). Results of a study optimizing the converter parameters are presented. Calculated efficiency for a 1000 vertical junction converter is 42.5 percent at a power density of 1 x 10 to the 3d power w/sq cm.

  9. Trade-offs between solar radiation management, carbon dioxide removal, emissions mitigation and adaptation

    NASA Astrophysics Data System (ADS)

    Vaughan, Naomi; Lenton, Timothy

    2010-05-01

    The possible use of solar radiation control strategies to counteract global warming is explored through a number scenarios of different anthropogenic CO2 emission reduction pathways and carbon dioxide removal interventions. Using a simple Earth system model, we illustrate the trade-offs between CO2 emission reduction, the use of carbon dioxide removal geoengineering interventions (‘negative emissions') and solar radiation management (SRM). These relationships are illustrated over a multi-centennial timescale, allowing sufficient time for the carbon-cycle to respond to the anthropogenic perturbation. The anthropogenic CO2 emission scenarios (focussing on those from fossil fuel combustion) range from more to less stringent mitigation of emissions and includes the scenario assumed in our previous work on the maximum cooling potential of different geoengineering options. Results are presented in terms of transient atmospheric CO2 concentration and global mean temperature from year 1900 to year 2500. Implementation of solar radiation control strategies requires an understanding of the timing and effect of terminating such an intervention, a so called ‘exit strategy'. The results illustrate a number of considerations regarding exit strategies, including the inherent commitment to either carbon dioxide removal interventions, or the length of time the solar radiation control mechanism must be maintained for. The impacts of the various trade-offs are also discussed in the context of adaptation and adaptive resilience. The results have a bearing on policy and long term planning by illustrating some of the important assumptions regarding implementation of solar radiation management. These include baseline assumptions about emission mitigation efforts, timescale of intervention maintenance and impacts on adaptation.

  10. Monolith catalysts for closed-cycle carbon dioxide lasers

    NASA Technical Reports Server (NTRS)

    Herz, Richard K.

    1994-01-01

    The general subject area of the project involved the development of solid catalysts that have high activity at low temperature for the oxidation of gases such as CO. The original application considered was CO oxidation in closed-cycle CO2 lasers. The scope of the project was subsequently extended to include oxidation of gases in addition to CO and applications such as air purification and exhaust gas emission control. The primary objective of the final phase grant was to develop design criteria for the formulation of new low-temperature oxidation catalysts utilizing Monte Carlo simulations of reaction over NASA-developed catalysts.

  11. Research on radiation induced laser plasmas

    NASA Technical Reports Server (NTRS)

    Schneider, R. T.; Rowe, M. J.; Carter, B. D.; Walters, R. A.; Cox, J. D.; Liang, R.; Roxey, T.; Zapata, L.

    1979-01-01

    The development of high power nuclear pumped lasers is discussed. The excitation mechanism of continuous wave (CW) HeNe nuclear pumped lasers is studied and a CO2 nuclear pumped laser is used to demonstrate the CW output in the order of watts. The assumption that high power densities are only achievable by volume fission fragment sources is used to identify laser gases which are compatible with UF6 by excited states lifetime measurements. The examination of Xe2, XeF, and KrF under nuclear irradiation to determine if they are good candidates for nuclear-pumped lasers is described.

  12. Laser interferometry of radiation driven gas jets

    NASA Astrophysics Data System (ADS)

    Swanson, Kyle James; Ivanov, Vladimir; Mancini, Roberto; Mayes, Daniel C.

    2017-06-01

    In a series of experiments performed at the 1MA Zebra pulsed power accelerator of the Nevada Terawatt Facility nitrogen gas jets were driven with the broadband x-ray flux produced during the collapse of a wire-array z-pinch implosion. The wire arrays were comprised of 4 and 8, 10μm-thick gold wires and 17μm-thick nickel wires, 2cm and 3cm tall, and 0.3cm in diameter. They radiated 12kJ to 16kJ of x-ray energy, most of it in soft x-ray photons of less than 1keV of energy, in a time interval of 30ns. This x-ray flux was used to drive a nitrogen gas jet located at 0.8cm from the axis of the z-pinch radiation source and produced with a supersonic nozzle. The x-ray flux ionizes the nitrogen gas thus turning it into a photoionized plasma. We used laser interferometry to probe the ionization of the plasma. To this end, a Mach-Zehnder interferometer at the wavelength of 266 nm was set up to extract the atom number density profile of the gas jet just before the Zebra shot, and air-wedge interferometers at 266 and 532 nm were used to determine the electron number density of the plasma right during the Zebra shot. The ratio of electron to atom number densities gives the distribution of average ionization state of the plasma. A python code was developed to perform the image data processing, extract phase shift spatial maps, and obtain the atom and electron number densities via Abel inversion. Preliminary results from the experiment are promising and do show that a plasma has been created in the gas jet driven by the x-ray flux, thus demonstrating the feasibility of a new experimental platform to study photoionized plasmas in the laboratory. These plasmas are found in astrophysical scenarios including x-ray binaries, active galactic nuclei, and the accretion disks surrounding black holes1. This work was sponsored in part by DOE Office of Science Grant DE-SC0014451.1R. C. Mancini et al, Phys. Plasmas 16, 041001 (2009)

  13. Intense-Field Photoionization of Molecules using Ultrashort Radiation Pulses: Carbon Disulfide and Carbon Dioxide

    NASA Astrophysics Data System (ADS)

    Beck, Joshua; Uiterwaal, Cornelis

    2016-05-01

    We experimentally investigate the photoionization and photofragmentation of molecules using intense fields from an 800 nm, femtosecond laser source and an experimental method that eliminates the focal volume effect without the need for data deconvolution. Targets include carbon disulfide and carbon dioxide. We show that ionization is insignificant for intensities that maximize alignment of carbon disulfide, which validates ultrafast electron diffraction experiments from aligned carbon disulfide. For comparison, we also investigate the analogous molecule carbon dioxide. In this molecule the molecular bonding orbitals include the n = 2 atomic orbitals of the oxygen atom, while in carbon disulfide the n = 3 orbitals of the sulfur atom contribute to the bonding. Recent work will be presented. This work supported by U.S. Dept. of Education GAANN Grants Nos. P200A090156 and P200A120188 and National Science Foundation EPSCoR RII Track-2 CA Award No. IIA-1430519 (Cooperative Nebraska-Kansas Grant).

  14. Thermal radiative near field transport between vanadium dioxide and silicon oxide across the metal insulator transition

    SciTech Connect

    Menges, F.; Spieser, M.; Riel, H.; Gotsmann, B.; Dittberner, M.; Novotny, L.; Passarello, D.; Parkin, S. S. P.

    2016-04-25

    The thermal radiative near field transport between vanadium dioxide and silicon oxide at submicron distances is expected to exhibit a strong dependence on the state of vanadium dioxide which undergoes a metal-insulator transition near room temperature. We report the measurement of near field thermal transport between a heated silicon oxide micro-sphere and a vanadium dioxide thin film on a titanium oxide (rutile) substrate. The temperatures of the 15 nm vanadium dioxide thin film varied to be below and above the metal-insulator-transition, and the sphere temperatures were varied in a range between 100 and 200 °C. The measurements were performed using a vacuum-based scanning thermal microscope with a cantilevered resistive thermal sensor. We observe a thermal conductivity per unit area between the sphere and the film with a distance dependence following a power law trend and a conductance contrast larger than 2 for the two different phase states of the film.

  15. Design of catalytic monoliths for closed-cycle carbon dioxide lasers

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  16. Analysis of electronically pulsed versus quasi-continuous wave carbon dioxide lasers in an animal model.

    PubMed

    Bellina, J H; Meandzija, M P; Schillt, V; Voros, J I; Berger, M; Fick, A C; Jackson, J D; McNaughton, S

    1984-12-15

    In this study we sought to compare laser tissue interaction in both the quasi-continuous waveform and electronically pulsed waveform of the carbon dioxide laser. An intramode analysis of the electronically pulsed form (at 350 and 650 pulses per second) was also undertaken. Intraperitoneal laser incisions were made on New Zealand white female virginal rabbits and tested at days 0, 5, 15, and 20. Testing involved proximal and midsection analysis of the laser sites to evaluate total area of vaporization, total area of tissue thermal damage, maximum diameter of injury at epithelial surface, maximum depth of laser penetration, angle of vaporization crater edges, and angle of tissue thermal injury of the three modes. Analysis of proximal versus midsection preparation revealed different zones of vaporization and injury within the same laser site. The zone of injury with respect to time was nonuniform, suggesting that the laser output in the electronically pulsed mode was not constant. An in vivo tissue lens phenomenon was also detected, resulting in a compound thermal vaporization and injury pattern.

  17. Quantum Quenching of Radiation Losses in Short Laser Pulses.

    PubMed

    Harvey, C N; Gonoskov, A; Ilderton, A; Marklund, M

    2017-03-10

    Accelerated charges radiate, and therefore must lose energy. The impact of this energy loss on particle motion, called radiation reaction, becomes significant in intense-laser matter interactions, where it can reduce collision energies, hinder particle acceleration schemes, and is seemingly unavoidable. Here we show that this common belief breaks down in short laser pulses, and that energy losses and radiation reaction can be controlled and effectively switched off by appropriate tuning of the pulse length. This "quenching" of emission is impossible in classical physics, but becomes possible in QED due to the discrete nature of quantum emissions.

  18. Testing Unruh Radiation with Ultra-Intense Lasers

    NASA Astrophysics Data System (ADS)

    Chen, Pisin; Tajima, Toshiki

    1997-04-01

    We point of that using the state-of-the-art (or soon to be) intense ultrafast laser technology, violent acceleration of electrons that may be suitable for testing general relativistic effects can be realized in the laboratory settings. In particular we demonstrate that the Unruh radiation is detectable, in principle, beyond the conventional radiation (most notably the Larmor radiation) background noise, by taking the advantages of their specific dependences on the laser power, their different characters in spectral-angular distributions, and the time structure of the signals.

  19. Quantum Quenching of Radiation Losses in Short Laser Pulses

    NASA Astrophysics Data System (ADS)

    Harvey, C. N.; Gonoskov, A.; Ilderton, A.; Marklund, M.

    2017-03-01

    Accelerated charges radiate, and therefore must lose energy. The impact of this energy loss on particle motion, called radiation reaction, becomes significant in intense-laser matter interactions, where it can reduce collision energies, hinder particle acceleration schemes, and is seemingly unavoidable. Here we show that this common belief breaks down in short laser pulses, and that energy losses and radiation reaction can be controlled and effectively switched off by appropriate tuning of the pulse length. This "quenching" of emission is impossible in classical physics, but becomes possible in QED due to the discrete nature of quantum emissions.

  20. Biological Studies On The Effect of Laser Radiation on Khapra Beetle Trogoderma granarium (Coleoptera : Dermestidae)

    NASA Astrophysics Data System (ADS)

    El-Nozahy, Adel M.; Ahmed, Salwa M. M. S.; Abdel-Kader, Mahomoud H.; Khalifa, Ibtesam A.

    2007-02-01

    The aim of the present work was to study the effect of Argon-ion laser and carbon dioxide laser radiation on Khapra beetle Trogoderma granarium and induced sterility. Radiobiological effects of irradiation were determined on adult stage of resulted 2-3 days-old pupae at LD30. The radiobiological studies induced determination of mortality, of, LD30, LD50 emergence, preovipositio period, fecundity, sterility, incubation period, larval duration, pupal duration and emergence of 1st generation. Experiments were carried out to determine the latent effect of irradiation on the wheat grains germination as well as the effects on the chemical constituents. In this respect irradiation of grains had no effect on the above ntioned parameters.

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

    NASA Astrophysics Data System (ADS)

    Schmitt, R.; Hugenschmidt, Manfred

    1996-05-01

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

  2. Effects of low-power laser radiation on mice immunity.

    PubMed

    Novoselova, E G; Glushkova, O V; Cherenkov, D A; Chudnovsky, V M; Fesenko, E E

    2006-02-01

    Because of large interest in biological effects of laser radiation used in laser therapy, the effect of extremely low-level red laser light intensity on the immune cell activity has been studied in the animal model with well-characterized macrophage and T cell populations as responder cells producing cytokines, protective proteins, active oxygen, and nitric compounds. To study of the possible side effects of laser immunotherapy we monitored the productions of cytokines, nitric oxide (NO), and heat shock protein 70 (Hsp70) in mice subjected to a periodic laser exposure for 1 month. Helium-neon laser radiation with the power of 0.2 mW/cm2 and wavelength of 632.8 nm was applied on two different mouse skin surfaces, i.e. a thymus projection area or a hind limb. Healthy NMRI male mice were irradiated repeatedly with laser light for 1 min with 48-h intervals for 30 days. The animals were divided into three groups of 25 mice. The first and the second groups were exposed to laser light, on the thymus and hind limb area, respectively. The third, sham-irradiated group served as a control. Early and prolonged effects of laser radiation on the levels of NO (by Griess assay), Hsp70 (by Western blot assay), tumor necrosis factors (TNF-alpha and TNF-beta) (by cytotoxic assay using L929 cells as targets), and interleukin-2 (IL-2) (by ELISA assay) were determined. The dynamics of immune responses to low-power laser light intensity was shown to be dependent on two factors, i.e. the cumulative dose and the localization of the irradiated surface. Besides, various populations of cells demonstrated different sensitivity to laser radiation, with T cells being more responsive among examined populations of the cells. Low intensity laser light induced an immune cell activity when the exposure duration did not exceed 10 days, while a more prolonged period of treatment generated more severe changes in the immune system, up to immunosuppression. The treatment of the thymus zone resulted in

  3. Extinction of CO2 Laser Radiation Under Adverse Weather Conditions

    DTIC Science & Technology

    1982-06-01

    81-1280 B0 91,a 4 TITLE (and Subtitle) S TYPE OF REPORT & PERIOD COVERED EXTINCTION OF CO2 LASER RADIATION UNDER FINAL Oct 78 Oct 81 ADVERSE WEATHER...CONDITIONS 6 PERFORMING O0G r_ r NUMBER 7. AUTHOR( s ) 8 CONTRACT OR GRANT NUMBER( s ) Dr. Vincent Chimelis ŝ PERFORMING ORGANIZATION NAME AND ADDRESS 10...number) Laser Propagation Rain Laser Extinction CO2 Lasers Adverse Weather Aerosol s - 20 RACT (Continue on reverse side If necessary and Identify by

  4. THz Radiation Generation via Laser Plasma Interaction Experiments

    NASA Astrophysics Data System (ADS)

    Yugami, Noboru; Higashiguchi, Takeshi

    2008-12-01

    Recently radiation generation from the interaction between laser and plasma is studied. Terahertz radiation from photo-conductive antenna which is based on semiconductor technology is widely used, The power is in the order of nano-watt level so that it is hard to use for application. On the other hand, terahertz radiation from laser plasma interaction is much higher than that of semiconductor technology. In our experiments, we have studied by use DARC (dc to ac radiation converter) mechanism by using YAG laser with nano-second pulse duration. DARC is novel radiation source using the interaction between laser-created ionization front and static electric field. The frequency of radiation is determined by both plasma density of ionization front and the geometry of DARC structure. We observed radiation pulse of frequency of 1.2 THz and pulse duration of 2 ps with ZnSe crystal as media detected by EO (electro-optics) sampling technique. Note from Publisher: This article contains the abstract only.

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  6. INTERACTION OF LASER RADIATION WITH MATTER: Resonance laser-induced ionisation of sodium vapour taking radiative transfer into account

    NASA Astrophysics Data System (ADS)

    Kosarev, N. I.; Shaparev, N. Ya

    2006-04-01

    The problem of ionisation of atomic sodium in the field of resonance laser radiation is numerically solved taking radiative transfer into account. Seed electrons are produced due to the mechanism of associative ionisation, then they gain energy in superelastic processes (collisions of the second kind) and initiate the avalanche ionisation of the medium by electron impact. We studied the effect of secondary radiation on the laser pulse propagation upon competition between the ionising and quenching electron collisions with excited atoms, on the kinetics of ionisation-induced vapour bleaching, and the plasma channel expansion in the form of a halo.

  7. [Study on Reduction of Radiation Exposure by Using Carbon Dioxide Angiography Catheter in Vascular Access Intervention Therapy(VAIVT)].

    PubMed

    Tsukada, Yasunori; Kakuchi, Yasushi

    2015-09-01

    In vascular access intervention therapy (VAIVT), carbon dioxide is used as negative contrast medium for patients with iodine allergy or for those who have vascular access but not started with dialysis yet and have not endangered their remaining kidney function. To capture the movement of jet-injected carbon dioxide during the carbon dioxide angiography, we performed imaging at a rate of 15 frames per second. This method has a higher level of radiation exposure than angiography using an iodine contrast medium. Therefore we developed a catheter with 20 helical side holes in the tip (carbon dioxide angiography catheter), which allows large numbers of tiny bubbles to be generated simultaneously. In our study, we evaluate whether the use of this catheter can reduce the number of frames taken per second thus reducing the radiation exposure. A comparative experiment with existing angiography catheters with no side holes suggested that the use of this carbon dioxide angiography catheter to be useful for reducing the radiation exposure to patients and operators. Moreover, angiography using this catheter is highly useful from viewpoint of improving the stenotic vesselvisibility and reducing the side effects of using carbon dioxide, and we expect that the carbon dioxide angiography method is effective for patients and operators.

  8. Counterpropagating Radiative Shock Experiments on the Orion Laser

    NASA Astrophysics Data System (ADS)

    Suzuki-Vidal, F.; Clayson, T.; Stehlé, C.; Swadling, G. F.; Foster, J. M.; Skidmore, J.; Graham, P.; Burdiak, G. C.; Lebedev, S. V.; Chaulagain, U.; Singh, R. L.; Gumbrell, E. T.; Patankar, S.; Spindloe, C.; Larour, J.; Kozlova, M.; Rodriguez, R.; Gil, J. M.; Espinosa, G.; Velarde, P.; Danson, C.

    2017-08-01

    We present new experiments to study the formation of radiative shocks and the interaction between two counterpropagating radiative shocks. The experiments are performed at the Orion laser facility, which is used to drive shocks in xenon inside large aspect ratio gas cells. The collision between the two shocks and their respective radiative precursors, combined with the formation of inherently three-dimensional shocks, provides a novel platform particularly suited for the benchmarking of numerical codes. The dynamics of the shocks before and after the collision are investigated using point-projection x-ray backlighting while, simultaneously, the electron density in the radiative precursor was measured via optical laser interferometry. Modeling of the experiments using the 2D radiation hydrodynamic codes nym and petra shows very good agreement with the experimental results.

  9. Treatment of Ankyloglossia with Carbon Dioxide (CO2) Laser in a Pediatric Patient

    PubMed Central

    Chiniforush, Nasim; Ghadimi, Sara; Yarahmadi, Nazli; Kamali, Abbas

    2013-01-01

    Introduction: Laser surgery as an alternative for conventional surgical procedure has gained special attention. Using Carbon Dioxide (CO2) laser has some benefits like less post-operative pain, swelling and infection, decrease in risk of metastasis and edema, and less bleeding providing dry sites for surgery. Case Report: A 12 years old boy with lingual frenum with indication for excision was referred to the laser department of Tehran University of medical sciences dental school.CO2 laser was used with 10600 nm wavelength, 1.5 W output power, 100 Hz frequency and 400 μsec pulse duration in non-contact mode. Results: The result of using CO2 laser was dry and bloodless field during operation, no post operative swelling, no pain or discomfort, with normal healing process. Conclusion: We suggest and stimulate the use of CO2 laser for soft tissue surgery because of elimination of suture, convenient coagulation, time saving, patients’ comfort and easy manipulation. PMID:25606307

  10. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Conversion of the energy of fast electrons to thermal plasma radiation

    NASA Astrophysics Data System (ADS)

    Vergunova, G. A.; Rozanov, Vladislav B.

    1992-01-01

    An analysis is made of the conversion of the energy of highly energetic fast electrons, generated by the action of CO2 laser radiation on a target, into characteristic radiation emitted by a plasma formed from shell targets which, for instance, may be present inside targets irradiated by the CO2 laser. Analytical formulas are obtained for the temperature of the converted radiation. The results show that it is possible to control this radiation by choosing the parameters of the target and of the fast electron flux. The efficiency of conversion into characteristic thermal radiation is found numerically to be 95%. This method of conversion is more favorable than direct interaction of CO2 laser radiation with a target since the emitting region is localized in the target mass. When a laser interacts with a target the mass of this region increases with time and so the temperature of the emitted radiation is lower than in the case when fast electrons act on the target.

  11. Vanadium dioxide based Fabry-Perot emitter for dynamic radiative cooling applications

    NASA Astrophysics Data System (ADS)

    Taylor, Sydney; Yang, Yue; Wang, Liping

    2017-08-01

    An asymmetric Fabry-Perot emitter is proposed with a lossless dielectric spacer inserted between a vanadium dioxide (VO2) thin film and an opaque aluminum substrate. Switchable mid-infrared emittance has been achieved due to the insulator-to-metal transition of VO2. When VO2 is dielectric below 341 K, the structure is highly reflective, thereby minimizing thermal radiation loss. Above 345 K, the VO2 becomes metallic and forms a Fabry-Perot resonance cavity with high broadband emissivity around 10 μm wavelength, providing a radiative cooling effect due to enhanced thermal emission. The radiative properties are calculated via a uniaxial transfer matrix method and Bruggeman effective medium theory. The physical mechanisms that provide the observed absorption enhancements are elucidated by examining the total phase shift in the multilayer structure and the phonon modes of VO2. When experiencing the VO2 phase transition, the radiative power of the proposed coating achieves a 6.5 fold enhancement for extraterrestrial spacecraft systems, and 7.3 fold enhancement for terrestrial systems such as buildings, making it a promising choice for dynamic radiative cooling applications in a variable environment. The findings here will facilitate research and development of novel coating materials for radiative cooling applications.

  12. Ultraviolet laser beam monitor using radiation responsive crystals

    DOEpatents

    McCann, Michael P.; Chen, Chung H.

    1988-01-01

    An apparatus and method for monitoring an ultraviolet laser beam includes disposing in the path of an ultraviolet laser beam a substantially transparent crystal that will produce a color pattern in response to ultraviolet radiation. The crystal is exposed to the ultraviolet laser beam and a color pattern is produced within the crystal corresponding to the laser beam intensity distribution therein. The crystal is then exposed to visible light, and the color pattern is observed by means of the visible light to determine the characteristics of the laser beam that passed through crystal. In this manner, a perpendicular cross sectional intensity profile and a longitudinal intensity profile of the ultraviolet laser beam may be determined. The observation of the color pattern may be made with forward or back scattered light and may be made with the naked eye or with optical systems such as microscopes and television cameras.

  13. Laser radiography forming bremsstrahlung radiation to image an object

    DOEpatents

    Perry, Michael D.; Sefcik, Joseph A.

    2004-01-13

    A method of imaging an object by generating laser pulses with a short-pulse, high-power laser. When the laser pulse strikes a conductive target, bremsstrahlung radiation is generated such that hard ballistic high-energy electrons are formed to penetrate an object. A detector on the opposite side of the object detects these electrons. Since laser pulses are used to form the hard x-rays, multiple pulses can be used to image an object in motion, such as an exploding or compressing object, by using time gated detectors. Furthermore, the laser pulses can be directed down different tubes using mirrors and filters so that each laser pulse will image a different portion of the object.

  14. Surface treatment of CFRP composites using femtosecond laser radiation

    NASA Astrophysics Data System (ADS)

    Oliveira, V.; Sharma, S. P.; de Moura, M. F. S. F.; Moreira, R. D. F.; Vilar, R.

    2017-07-01

    In the present work, we investigate the surface treatment of carbon fiber-reinforced polymer (CFRP) composites by laser ablation with femtosecond laser radiation. For this purpose, unidirectional carbon fiber-reinforced epoxy matrix composites were treated with femtosecond laser pulses of 1024 nm wavelength and 550 fs duration. Laser tracks were inscribed on the material surface using pulse energies and scanning speeds in the range 0.1-0.5 mJ and 0.1-5 mm/s, respectively. The morphology of the laser treated surfaces was investigated by field emission scanning electron microscopy. We show that, by using the appropriate processing parameters, a selective removal of the epoxy resin can be achieved, leaving the carbon fibers exposed. In addition, sub-micron laser induced periodic surface structures (LIPSS) are created on the carbon fibers surface, which may be potentially beneficial for the improvement of the fiber to matrix adhesion in adhesive bonds between CFRP parts.

  15. CONTROL OF LASER RADIATION PARAMETERS: Multichannel optical modulator for a laser diode array

    NASA Astrophysics Data System (ADS)

    Derzhavin, S. I.; Kuz'minov, V. V.; Mashkovskii, D. A.; Timoshkin, V. N.

    2007-07-01

    The possibility of the development of a multichannel electrooptical modulator of laser radiation with a large diffraction divergence and a small coherence length is studied experimentally and its design is described.

  16. Monolith catalysts for closed-cycle carbon dioxide lasers

    NASA Technical Reports Server (NTRS)

    Herz, Richard K.; Badlani, Ajay

    1991-01-01

    The objective was to explore ways of making a monolithic form of catalyst for CO2 lasers. The approach chosen was to pelletize the catalyst material, Au/MnO2 powder, and epoxy the pellets to stainless steel sheets as structural supports. The CO oxidation reaction over Au/MnO2 powder was found to be first overall, and the reaction rate constant at room temperature was 4.4 +/- 0.3 cc/(g x sec). The activation energy was 5.7 kcal/mol. The BET surface area of the pellets was found to vary from 125 to 140 sq m/g between different batches of catalyst. Pellets epoxied to stainless steel strips showed no sign of fracture or dusting when subjected to thermal tests. Pellets can be dropped onto hard surfaces with chipping of edges but no breakage of the pellets. Mechanical strength tests performed on the pellets showed that the crush strength is roughly one-fourth of the pelletizing force. The apparent activity and activation energy over the pellets were found to be less than over the powdered form of the catalyst. The lower apparent activity and activation energy of the pellets are due to the fact that the internal surface area of a pellet is not exposed to the reactant concentration present in the flowing gas as a result of intrapellet diffusion resistance. Effectiveness factors varied from 0.44, for pellets having thickness of 2 mm and attached with epoxy to a stainless steel strip. The epoxy and the stainless steel strip were found to simply block off one of the circular faces of the pellets. The epoxy did not penetrate the pellets and block the active sites. The values of the effective diffusivities were estimated to be between 2.3 x 10(exp -3) and 4.9 x 10(exp -3) sq cm/s. With measurements performed on one powder sample and one pellet configuration, reasonable accurate predictions can be made of conversions that would be obtained with other pellet thickness and configurations.

  17. [Two-step exposure of biological objects to infrared laser and microwave radiation].

    PubMed

    Kol'tsov, Iu V; Korolev, V N; Kusakin, S A

    1999-01-01

    The effect of two-step exposure of bacterial objects to infrared laser and microwave pulse radiations was studied. The effect is determined by the time interval between two excitation steps and pulse duration. It was shown that the biologically active dose of microwave radiation is much lower than that of infrared laser radiation; however, laser radiation induces a stronger cellular response. It was found that microwaves enhance the efficiency of infrared laser radiation.

  18. Investigation of ultrafast laser-driven radiative blast waves.

    PubMed

    Edwards, M J; MacKinnon, A J; Zweiback, J; Shigemori, K; Ryutov, D; Rubenchik, A M; Keilty, K A; Liang, E; Remington, B A; Ditmire, T

    2001-08-20

    We have examined the evolution of cylindrically symmetric blast waves produced by the deposition of femtosecond laser pulses in gas jets. In high- Z gases radiative effects become important. We observe the production of an ionization precursor ahead of the shock front and deceleration parameters below the adiabatic value of 1/2 (for a cylinder), an effect expected when the blast wave loses energy by radiative cooling. Despite significant radiative cooling, the blast waves do not appear to develop thin shell instabilities expected for strongly radiative waves. This is believed to be due to the stabilizing effect of a relatively thick blast wave shell resulting in part from electron thermal conduction effects.

  19. Carbon dioxide laser laparoscopy by means of a 3.0-mm diameter rigid wave guide.

    PubMed

    Baggish, M S; Sze, E; Badawy, S; Choe, J

    1988-09-01

    Rigid carbon dioxide wave guides measuring 300 to 500 mm in length and 3.0 mm in diameter were evaluated in rabbits and humans. The wave guide provided an effective laser delivery system for operative laparoscopy. The tested guide was introduced into the abdominal cavity alternatively via the operating channel of a 9-mm operating laparoscope, through the central channel of a smoke evacuation/irrigation cannula, or via a 3.25-mm second puncture trocar. In contrast to previously tested flexible guides, the rigid device transmitted a visible helium-neon aiming beam, power up to 50 watts, and a beam diameter of less than 1 mm. The hollow guide was kept free of smoke by-products by continuous purging with carbon dioxide gas flowing at 800 to 1000 cc per minute. All wave guides could be sterilized by ethylene oxide gas or Cidex (Surgikos, Arlington, TX) soaking. Fourteen women with a variety of reproductive disorders underwent laser laparoscopy. The rigid wave guide was fired at distances ranging from less than 1 mm to 30 mm from the target and performed with maximal impact at distances of 3 to 5 mm. Perhaps the greatest advantage of this system is its ability to focus-defocus while directly coupling to the handpiece of standard lasers and requiring no special alignment procedures.

  20. Optical properties and radiation stability of submicro- and nanopowders titanium dioxide measured in situ

    NASA Astrophysics Data System (ADS)

    Mikhailov, M. M.; Neshchimenko, V. V.; Yuryev, S. A.

    2016-04-01

    This study carried out an in situ and external investigation on the reflective spectra of micro- and nanopowders titanium dioxide before and after irradiation by 30 keV electrons. The particle sizes range from 60-240 nm. It was established that the decrease in the particle size leads to an increase in intrinsic defects. The particles with intrinsic defects are then transformed into absorption centers during irradiation as a result of optical degradation of TiO2 powders. High radiation stability has particle sizes range from 80-160 nm.

  1. Warming early Mars with carbon dioxide clouds that scatter infrared radiation.

    PubMed

    Forget, F; Pierrehumbert, R T

    1997-11-14

    Geomorphic evidence that Mars was warm enough to support flowing water about 3.8 billion years ago presents a continuing enigma that cannot be explained by conventional greenhouse warming mechanisms. Model calculations show that the surface of early Mars could have been warmed through a scattering variant of the greenhouse effect, resulting from the ability of the carbon dioxide ice clouds to reflect the outgoing thermal radiation back to the surface. This process could also explain how Earth avoided an early irreversible glaciation and could extend the size of the habitable zone on extrasolar planets around stars.

  2. Absorption of CO laser radiation by NO

    NASA Technical Reports Server (NTRS)

    Hanson, R. K.; Monat, J. P.; Kruger, C. H.

    1976-01-01

    The paper describes absorption calculations and measurements at selected infrared CO laser wavelengths which are nearly coincident with absorption lines in the fundamental vibration-rotation band of NO near 5.3 microns. Initial work was directed towards establishing the optimal CO laser-NO absorption line coincidence for high temperature applications. Measurements of the absorption coefficient at this optimal laser wavelength were carried out, first using a room-temperature absorption cell for high-temperature calculations and then using a shock tube, for the temperature range 630-4000 K, to validate the high temperature calculations.

  3. Simulation of free-electron lasers seeded with broadband radiation

    SciTech Connect

    Bajlekov, Svetoslav; Fawley, William; Schroeder, Carl; Bartolini, Riccardo; Hooker, Simon

    2011-03-10

    The longitudinal coherence of free-electron laser (FEL) radiation can be enhanced by seeding the FEL with high harmonics of an optical laser pulse. The radiation produced by high-harmonic generation (HHG), however, has a fast-varying temporal profile that can violate the slowly varying envelope approximation and limited frequency window that is employed in conventional free-electron laser simulation codes. Here we investigate the implications of violating this approximation on the accuracy of simulations. On the basis of both analytical considerations and 1D numerical studies, it is concluded that, for most realistic scenarios, conventional FEL codes are capable of accurately simulating the FEL process even when the seed radiation violates the slowly varying envelope approximation. We additionally discuss the significance of filtering the harmonic content of broadband HHG seeds.

  4. Partially coherent radiation from lasers, undulators, and laser produced plasmas

    NASA Astrophysics Data System (ADS)

    Iskander, Nasif; Wang, Nadine

    The coherence properties of several existing and proposed sources of soft X-rays are compared with emphasis on the LLNL Se laser. Average and peak values of spectral brightness and coherent power are calculated and plotted. Coherent power is plotted in units of watts for coherence lengths of 1 micron and 10 microns (two useful lengths of experiments) as well as 200 microns (to illustrate the natural long coherence length of the LLNL Se laser).

  5. LASERS IN MEDICINE: Structure of matrices for the transformation of laser radiation by biofractals

    NASA Astrophysics Data System (ADS)

    Angel'skii, O. V.; Ushenko, A. G.; Arkhelyuk, A. D.; Ermolenko, S. B.; Burkovets, D. N.

    1999-12-01

    The changes in the state of polarisation of laser radiation transformed by biofractal objects are examined. The orientational angular structure of the matrix elements of the operator representing the optical properties of biofractals with different morphological structures (mineralised collagen fibres and myosin bundles) is investigated. An optical model for the description of fractal laser fields under the conditions of single light scattering is proposed.

  6. Synchrotron radiation from a curved plasma channel laser wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Palastro, J. P.; Kaganovich, D.; Hafizi, B.; Chen, Y.-H.; Johnson, L. A.; Peñano, J. R.; Helle, M. H.; Mamonau, A. A.

    2017-03-01

    A laser pulse guided in a curved plasma channel can excite wakefields that steer electrons along an arched trajectory. As the electrons are accelerated along the curved channel, they emit synchrotron radiation. We present simple analytical models and simulations examining laser pulse guiding, wakefield generation, electron steering, and synchrotron emission in curved plasma channels. For experimentally realizable parameters, a ˜2 GeV electron emits 0.1 photons per cm with an average photon energy of multiple keV.

  7. Resonant four-wave mixing of laser radiation in plasmas

    SciTech Connect

    Lal, A.; Joshi, C. )

    1991-10-01

    Experimental evidence of resonant four-wave mixing of CO{sub 2} laser radiation in a plasma is presented for the first time to our knowledge. Comparison of the experiment with theory indicates that, while collisions lead to a narrow spectral width of the ion acoustic resonance, convection and detuning owing to laser heating limit the enhancement of the signal reflectivity to below the expected value.

  8. Fractional Carbon Dioxide Laser for Keratosis Pilaris: A Single-Blind, Randomized, Comparative Study.

    PubMed

    Vachiramon, Vasanop; Anusaksathien, Pattarin; Kanokrungsee, Silada; Chanprapaph, Kumutnart

    2016-01-01

    Objective. Keratosis pilaris (KP) is a common condition which can frequently be cosmetically disturbing. Topical treatments can be used with limited efficacy. The objective of this study is to evaluate the effectiveness and safety of fractional carbon dioxide (CO2) laser for the treatment of KP. Patients and Methods. A prospective, randomized, single-blinded, intraindividual comparative study was conducted on adult patients with KP. A single session of fractional CO2 laser was performed to one side of arm whereas the contralateral side served as control. Patients were scheduled for follow-up at 4 and 12 weeks after treatment. Clinical improvement was graded subjectively by blinded dermatologists. Patients rated treatment satisfaction at the end of the study. Results. Twenty patients completed the study. All patients stated that the laser treatment improved KP lesions. At 12-week follow-up, 30% of lesions on the laser-treated side had moderate to good improvement according to physicians' global assessment (p = 0.02). Keratotic papules and hyperpigmentation appeared to respond better than the erythematous component. Four patients with Fitzpatrick skin type V developed transient pigmentary alteration. Conclusions. Fractional CO2 laser treatment may be offered to patients with KP. Dark-skinned patients should be treated with special caution.

  9. Fractional Carbon Dioxide Laser for Keratosis Pilaris: A Single-Blind, Randomized, Comparative Study

    PubMed Central

    Vachiramon, Vasanop; Anusaksathien, Pattarin; Kanokrungsee, Silada; Chanprapaph, Kumutnart

    2016-01-01

    Objective. Keratosis pilaris (KP) is a common condition which can frequently be cosmetically disturbing. Topical treatments can be used with limited efficacy. The objective of this study is to evaluate the effectiveness and safety of fractional carbon dioxide (CO2) laser for the treatment of KP. Patients and Methods. A prospective, randomized, single-blinded, intraindividual comparative study was conducted on adult patients with KP. A single session of fractional CO2 laser was performed to one side of arm whereas the contralateral side served as control. Patients were scheduled for follow-up at 4 and 12 weeks after treatment. Clinical improvement was graded subjectively by blinded dermatologists. Patients rated treatment satisfaction at the end of the study. Results. Twenty patients completed the study. All patients stated that the laser treatment improved KP lesions. At 12-week follow-up, 30% of lesions on the laser-treated side had moderate to good improvement according to physicians' global assessment (p = 0.02). Keratotic papules and hyperpigmentation appeared to respond better than the erythematous component. Four patients with Fitzpatrick skin type V developed transient pigmentary alteration. Conclusions. Fractional CO2 laser treatment may be offered to patients with KP. Dark-skinned patients should be treated with special caution. PMID:27247936

  10. Proximal gastric vagotomy with carbon dioxide laser: Experimental studies in animals

    SciTech Connect

    Kadota, T.; Mimura, K.; Kanabe, S.; Ohsaki, Y.; Tamakuma, S. )

    1990-06-01

    Proximal gastric vagotomy has been widely used as a surgical treatment for peptic ulcer disease. However, it is technically complex and time-consuming. Moreover, it may cause circulatory problems in the gastric mucosa. We have reported a new method of blood flow-preserving vagotomy with a carbon dioxide laser (CO2 laser vagotomy) developed in our laboratory. To assess its efficacy, we used cysteamine-induced ulcer and measured gastric mucosal blood flow in rats. The incidence of cysteamine-induced ulcer formation was reduced significantly in the group that underwent CO{sub 2} laser vagotomy compared with a group treated with proximal gastric vagotomy. Gastric mucosal blood flow was significantly better in the CO{sub 2} laser vagotomy group. Long-term follow-up of acid reduction was evaluated in dogs by the pentagastrin-stimulation test. Acid reduction in dogs was satisfactory during the 12 months of this study. CO{sub 2} laser vagotomy is a new, easy, time-saving, and circulatory-preserving technique for peptic ulcer disease.

  11. ARTICLES: High-power laser radiation damage to transparent insulators

    NASA Astrophysics Data System (ADS)

    Gavrilov, B. G.; Kulikov, V. I.; Pedanov, V. V.

    1982-11-01

    An experimental investigation was made of the kinetics of the post-breakdown phenomena accompanying the focusing of high-power laser radiation inside transparent insulators (using the example of single-crystal potassium alum). Measurements were made of the rate of growth of the damage region and of the propagation velocity of the elastic wave, its amplitude and wavelength. The dimensions of the breakdown region were compared with those of the damage zone in the insulator. An analysis was made of the laser radiation energy distribution in the observed phenomenon.

  12. Peculiarities of radiation formation in laser systems for remote sensing

    NASA Astrophysics Data System (ADS)

    Panchenko, Yury N.; Andreev, M. V.; Losev, V. F.; Puchikin, A. V.

    2015-02-01

    The study results of a high-quality radiation formation in the UV and IR spectral ranges for using in lidar systems to detect the vapors of nitric oxide and complex molecules, including data radicals, are discussed. The influence of the existing cavity losses on the radiation formation in the dispersion cavity is studied.The development of KrF laser with a broad spectral band adjustment of 247.5-249.5 nm and high energy are presented about. The possibility of pulse formation with duration of 30 ns in CO2 laser is shown.

  13. Germ cell DNA quantification shortly after IR laser radiation.

    PubMed

    Bermúdez, D; Carrasco, F; Diaz, F; Perez-de-Vargas, I

    1991-01-01

    The immediate effect of IR laser radiation on rat germ cells was studied by cytophotometric quantification of the nuclear DNA content in testicular sections. Two different levels of radiation were studied: one according to clinical application (28.05 J/cm2) and another known to increase the germ cell number (46.80 J/cm2). The laser beam induced changes in the germ cell DNA content depending on the cell type, the cell cycle phase and the doses of radiation energy applied. Following irradiation at both doses the percentage of spermatogonia showing a 4c DNA content was increased, while the percentage of these with a 2c DNA content was decreased. Likewise, the percentages of primary spermatocytes with a DNA content equal to 4c (at 28.05 J/cm2), between 2c and 4c (at 46.80 J/cm2) and higher than 4c (at both doses) were increased. No change in the mean spermatid DNA content was observed. Nevertheless, at 46.80 J/cm2 the percentages of elongated spermatids with a c or 2c DNA content differed from the controls. Data show that, even at laser radiation doses used in therapy, the germ cell DNA content is increased shortly after IR laser radiation.

  14. Radiation temperature measurements in laser-heated hohlraums

    SciTech Connect

    Cobble, J.A.; Goldman, S.R.; Bessarab, A.V.; Kunin, A.V.; Tokarev, V.A.

    1997-11-01

    Two x-ray spectrographs have been used on the Trident laser at LANL to monitor the radiation temperature of small Au hohlraums. The cylindrical targets are smaller than 1 mm. The x radiation produced by {approximately} 400 J of 0.53-{micro}m laser light is detected with a 7-channel VNIIEF soft-x-ray spectrometer. Each channel employs a multi-layer mirror and a filter to limit the channel bandwidth to 1--3% of the channel energy. X rays are detected with calibrated Al x-ray diodes. A second spectrometer is based on a free-standing Au transmission grating for spectral dispersion and a multi-channel diamond photo-conductive device detector. The small hohlraum results are consistent with radiation temperatures exceeding 100 eV. Simple computer modeling shows that late in the plasma discharge, radiation of this temperature is emitted from the target.

  15. Comparison of the erbium-yttrium aluminum garnet and carbon dioxide lasers for in vitro bone and cartilage ablation

    SciTech Connect

    Gonzalez, C.; van de Merwe, W.P.; Smith, M.; Reinisch, L. )

    1990-01-01

    The in vitro bone- and cartilage-ablation characteristics of the solid-state erbium:yttrium aluminum garnet laser were compared to those of the carbon dioxide laser. Ablations of fresh, frozen cadaver septal cartilage and maxillary sinus bone were performed using total energies between 1 and 6 J. Specimens were studied using hematoxylin and eosin stain and digitized, computer-assisted measurements of 35-mm photographs. Erbium-yttrium aluminum garnet-ablated bone averaged 5 microns of adjacent tissue thermal injury, compared with 67 microns with carbon dioxide-ablated bone. Erbium-yttrium aluminum garnet-ablated cartilage averaged 2 microns of adjacent tissue thermal injury, compared with 21 microns with the carbon dioxide-ablated cartilage. The tissue-ablation characteristics of the erbium-yttrium aluminum garnet laser are promising for future otolaryngologic applications.

  16. Interaction of repetitively pulsed high energy laser radiation with matter

    NASA Astrophysics Data System (ADS)

    Hugenschmidt, M.

    1986-05-01

    Laser target interaction processes and methods of improving the overall energy balance are discussed. This can be achieved with high repetition rate pulsed lasers even for initially highly reflecting materials, such as metals. Experiments were performed using a pulsed CO2 laser at mean powers up to 2 KW and repetition rates up to 100 Hz. The rates of temperature rise of aluminum for example are increased by more than a factor of 3 as compared to cw-radiation of comparable power density. Similar improvements are found for the overall absorptivities, that are increased by more than an order of magnitude.

  17. Interaction of laser radiation with metal island films

    NASA Astrophysics Data System (ADS)

    Benditskii, A. A.; Viduta, L. V.; Ostranitsa, A. P.; Tomchuk, P. M.; Iakovlev, V. A.

    1986-08-01

    The emission phenomena arising during the interaction of pulsed laser emission with island films are examined with reference to experimental results obtained for island films of gold irradiated by a CO2 laser at a wavelength of 10.6 microns. Well reproducible emission pulses that are also accompanied by light pulses are produced at intensities less than 10 to the 5th W/sq cm, with the film structure remaining unchanged. The maximum energy of the electrons emitted under the effect of laser radiation is estimated at 3 eV; the work function is 2.1 eV.

  18. Laser Electron Generator of the X-Ray Radiation

    NASA Astrophysics Data System (ADS)

    Artyukov, I. A.; Bessonov, E. G.; Vinogradov, A. V.; Gorbunkov, M. V.; Maslova, Yu. Ya.; Popov, N. L.; Postnov, A. A.; Uspenski, Yu. A.; Feshchenko, R. M.; Shabalin, Yu. V.; Slovokhotov, Yu. L.; Zubavichus, Ya. V.; Ishanov, B. S.; Poseryaev, A. V.; Shvedunov, V. I.; Kostrukov, P. V.; Tunkin, V. G.

    The possibility of the creation and the application prospects of the laser-electron X-ray generator based on the Thompson scattering of the laser radiation on a bunch of relativistic electrons are considered. Such a generator fills the existing gap between X-ray tubes and synchrotron sources, which is several orders of magnitude in terms of the brightness, average intensity, size and also in the construction and exploitation costs. The layout of beam-lines and experimental stations intended for the applications of the X-ray laser-electron generator to the investigation of the elemental composition and material structure and biological objects is discussed.

  19. EFFECTS OF LASER RADIATION ON MATTER: Growth of periodic structures on the surface of germanium subjected to pulsed laser radiation

    NASA Astrophysics Data System (ADS)

    Barsukov, D. O.; Gusakov, G. M.; Frolov, A. I.

    1991-12-01

    An experimental investigation was made of the dynamics of growth of periodic surface structures due to the interaction with pulsed laser radiation. Samples of Ge were subjected to laser pulses (λ = 1.06 μm, τ = 70 ns) with energy densities in the range 0.5-5.5 J/cm2. An investigation was made of the dynamics of the first-order diffraction of probe (λ = 0.53 μm) laser pulses with a time resolution 4 ns when p- and s-polarized laser radiation was incident at angles close to normal. A strong nonlinearity of the growth of such periodic surface structures was observed. The energy density from which such growth began depended on the quality of the polished Ge surface. The parameters of the dynamics of the growth of these structures were estimated.

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

    PubMed

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

    2014-03-01

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

  1. Development of Technologies to Utilize Laser Plasma Radiations Sources for Radiation Effects Sciences

    SciTech Connect

    Davis, J F

    2007-01-31

    This final report will cover work performed over the period of November 11, 2005 to September 30, 2006 on the contract to develop technologies using laser sources for radiation effects sciences. The report will discuss four topic areas; the laser source experiments on the Gekko Laser at Osaka, Japan, planning for the Charge State Freeze Out experiments to be performed in calendar year 2007, a review of previous xenon gasbags on the LANL Trident laser to provide planning support to the May-June 2007 HELEN experiments.

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

    NASA Technical Reports Server (NTRS)

    Spiers, Gary D.; Menzies, Robert T.

    2008-01-01

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

  3. Necrobiotic xanthogranuloma associated with lymphoplasmacytic lymphoma. Palliative treatment with carbon dioxide laser.

    PubMed

    Vieira, V; Del Pozo, J; Martínez, W; Veiga-Barreiro, J A; Fonseca, E

    2005-01-01

    Necrobiotic xanthogranuloma (NXG) with paraproteinemia is a rare non-x histiocytosis with conspicuous lesions mainly located on the periorbital skin. A 68-year-old woman, with a previous history of lymphoplasmacytic lymphoma associated with IgG monoclonal gammopathy over a period of almost 4 years, presented typical lesions of NXG on the periorbital regions and left buttock. Treatment with dioxide carbon laser resulted in great improvement of cutaneous lesions, and no evidence of relapse after a 12-month follow-up. The association of NXG with lymphoplasmacytic lymphoma has not been previously described to our knowledge. The treatment of these lesions represents a true challenge for the clinician and palliative treatment of cutaneous lesions of NXG with CO(2) laser may constitute an alternative treatment in selected cases.

  4. Histologic evaluation of the width of soft tissue necrosis adjacent to carbon dioxide laser incisions

    SciTech Connect

    Pogrel, M.A.; McCracken, K.J.; Daniels, T.E. )

    1990-11-01

    This study evaluated the width of tissue necrosis lateral to carbon dioxide laser incisions on human intraoral excisional biopsy specimens. Measurements were made on specimens including epithelium, muscle, dense and loose connective tissue, and salivary gland. Results showed a mean width of tissue necrosis of 86 microns in epithelium, 85 microns in muscle, 51 microns in loose connective tissue, 96 microns in dense connective tissue, and 41 microns in salivary gland. The range of thermal necrosis in different tissue types is probably based on the water content within each type. A cellular partially homogenized zone of reversible thermal damage up to 500 microns in width was visible adjacent to the zone of thermal necrosis. The relatively narrow width of tissue necrosis with this technique may account for the claimed superior properties of laser-induced wounds compared with those created by electrosurgery.

  5. Optical fiber transmission of high power excimer laser radiation.

    PubMed

    Pini, R; Salimbeni, R; Vannini, M

    1987-10-01

    An experimental investigation of optical fiber transmission of high power excimer laser radiation is presented. Different types of commercially available UV fiber have been tested, measuring energy handling capabilities and transmission losses of short samples at the XeCl (308-nm) and KrF (249-nm) wavelengths by using a standard excimer laser. A power density dependent damage process has been observed over 1 GW/cm(2). Fiber losses due to different radii of curvature are also reported. Experimental results have been examined to evaluate the effectiveness of excimer laser transmission through optical fibers for such medical uses as laser angioplasty, including also a comparison between the use of KrF or XeCl emission lines for this purpose. Finally, optimum excimer laser characteristics to increase the energy coupling in fibers are discussed.

  6. Target voltage response in reaction to laser radiation

    NASA Astrophysics Data System (ADS)

    Harkins, Richard M.

    1988-12-01

    The five microsecond, 15 joule, pulsed CO2 Laser was used to irradiate polished 2024 aluminum targets. The target voltage response (TVR) was measured with respect to the incident laser radiation and showed a pulse width on the order of 30 nanoseconds. The voltage was measured at values from 22 to 140 volts with resistances varying from one ohm to two mega-ohms. The TVR was correlated to the emission and blow-off of electrons from the target surface and the possible ignition of a Laser Supported Detonation wave. The TVR, laser pulse, and flash associated with target surface breakdown were time correlated and shown to happen within the first 170 nanoseconds of the five microsecond laser pulse. Currents up to 500 amps were observed when the resistance to ground was reduced to less than 1 ohm. Also, the magnitude of the TVR was shown to be a function of background gas pressure.

  7. Phenol Photocatalytic Degradation by Advanced Oxidation Process under Ultraviolet Radiation Using Titanium Dioxide

    PubMed Central

    Nickheslat, Ali; Amin, Mohammad Mehdi; Izanloo, Hassan; Fatehizadeh, Ali; Mousavi, Seyed Mohammad

    2013-01-01

    Background. The main objective of this study was to examine the photocatalytic degradation of phenol from laboratory samples and petrochemical industries wastewater under UV radiation by using nanoparticles of titanium dioxide coated on the inner and outer quartz glass tubes. Method. The first stage of this study was conducted to stabilize the titanium dioxide nanoparticles in anatase crystal phase, using dip-coating sol-gel method on the inner and outer surfaces of quartz glass tubes. The effect of important parameters including initial phenol concentration, TiO2 catalyst dose, duration of UV radiation, pH of solution, and contact time was investigated. Results. In the dip-coat lining stage, the produced nanoparticles with anatase crystalline structure have the average particle size of 30 nm and are uniformly distributed over the tube surface. The removal efficiency of phenol was increased with the descending of the solution pH and initial phenol concentration and rising of the contact time. Conclusion. Results showed that the light easily passes through four layers of coating (about 105 nm). The highest removal efficiency of phenol with photocatalytic UV/TiO2 process was 50% at initial phenol concentration of 30 mg/L, solution pH of 3, and 300 min contact time. The comparison of synthetic solution and petrochemical wastewater showed that at same conditions the phenol removal efficiency was equal. PMID:23710198

  8. Structure of a laser-driven radiative shock

    NASA Astrophysics Data System (ADS)

    Chaulagain, U.; Stehlé, C.; Larour, J.; Kozlová, M.; Suzuki-Vidal, F.; Barroso, P.; Cotelo, M.; Velarde, P.; Rodriguez, R.; Gil, J. M.; Ciardi, A.; Acef, O.; Nejdl, J.; de Sá, L.; Singh, R. L.; Ibgui, L.; Champion, N.

    2015-12-01

    Radiative shocks are ubiquitous in stellar environments and are characterized by high temperature plasma emitting a considerable fraction of their energy as radiation. The physical structure of these shocks is complex and experimental benchmarks are needed to provide a deeper understanding of the physics at play. In addition, experiments provide unique data for testing radiation hydrodynamics codes which, in turn, are used to model astrophysical phenomena. Radiative shocks have been studied on various high-energy laser facilities for more than a decade, highlighting the importance of radiation on the plasma dynamics. Particularly the PALS facility has focused in producing radiative shocks with typical velocities of ∼50-60 km s-1 in xenon at a fraction of a bar. In addition PALS has the unique capability of producing the most powerful XUV laser available today (21.2 nm (58.4 eV), 0.15 ns), opening the door to new diagnostics of dense plasmas. Here we present results of XUV imaging of the precursor and post-shock structure of radiative shocks generated in xenon in this facility, together with time-and-space resolved measurements of the XUV self-emission using fast diode. The experimental results are interpreted with the help of 2D ARWEN radiative hydrodynamics simulations and state-of-the art monochromatic opacities.

  9. Use of the carbon dioxide laser in guided tissue regeneration wound healing in the beagle dog

    NASA Astrophysics Data System (ADS)

    Rossmann, Jeffrey A.; Parlar, Ates; Abdel-Ghaffar, Khaled A.; El-Khouli, Amr M.; Israel, Michael

    1996-04-01

    The concept of guided tissue regeneration (GTR) allowing cells from the periodontal ligament and alveolar bone to repopulate the treated root surface has shown the ability to obtain periodontal new attachment. Healing studies have also shown that conventional GTR therapy still does not exclude all the epithelium. This epithelial proliferation apically interferes with the establishment of the new connective tissue attachment to the root surface. The objective of this research study was to examine whether controlled de-epithelialization with the carbon dioxide laser during the healing phase after periodontal surgery, would retard the apical migration of the epithelium and thereby enhance the results obtained through guided tissue regeneration. Eight beagle dogs were used, the experimental side received de-epithelialization with the CO2 laser in conjunction with flap reflection and surgically created buccal osseous defects. Selected defects on each side were treated with ePTFE periodontal membranes. The laser de-epithelialization was repeated every 10 days until removal of the membranes. The control side received the same surgical treatment without laser application. This experimental design allowed histologic study of the new attachment obtained in defects treated with flap debridement with or without laser de-epithelialization and with or without ePTFE membranes. A statistical analysis was performed on the histometric data from 48 teeth in the 8 dogs after 4 months of healing. The results showed significant amounts of new attachment obtained from all four treatment modalities with no statistically significant differences for any one treatment. However, the trend towards enhanced regeneration with the combined treatment of laser and membrane vs. membrane alone or debridement alone was evident. The histologic analysis revealed a significant amount of newly formed `fat cementum' seen only on the laser treated teeth. This feature was the most remarkable finding of the

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

    PubMed Central

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

    2017-01-01

    Background: Acne is a very common skin disease in which scars are seen in 95% of the patients. Although numerous treatments have been recommended, researchers are still searching for a single modality to treat the complication due to its variety in shape and depth. We compared the effects of fractional carbon dioxide (CO2) laser alone and in combination with subcision in the treatment of atrophic acne scars. Materials and Methods: This clinical trial study was performed in Skin Diseases and Leishmaniasis Research Center (Isfahan, Iran) during 2011–2012. Eligible patients with atrophic acne scars were treated with fractional CO2 laser alone (five sessions with 3-week interval) on the right side of the face and fractional CO2 laser plus subcision (one session using both with four sessions of fractional CO2 laser, with 3-week interval) on the left side. The subjects were visited 1, 2, and 6 months after the treatment. Patient satisfaction rate was analyzed using SPSS 20 software. Results: The average of recovery rate was 54.7% using the combination method and 43.0% using laser alone (P < 0.001). The mean patient satisfaction was significantly higher with the combination method than laser alone (6.6 ± 1.2 vs. 5.2 ± 1.8; P < 0.001). Bruising was only seen with the combination method and lasted for 1 week in 57.0% and for 2 weeks in 43.0%. Erythema was seen in both methods. Postinflammatory pigmentation and hyperpigmentation were associated with combination method. No persistent side effects were seen after 6 months. Conclusion: Using a combination of subcision and laser had suitable results regarding scar recovery and satisfaction rate. PMID:28349023

  11. Application of Laser-Induced Bone Therapy by Carbon Dioxide Laser Irradiation in Implant Therapy

    PubMed Central

    Naka, Takahiro; Yokose, Satoshi

    2012-01-01

    This study evaluated the application of laser-induced bone therapy (LIBT) to reduce implant healing time in rat tibia. Twenty 10-week-old female Sprague-Dawlay rats were used. The rats received laser irradiation (laser group) or sham operation (control group) on either side of the tibia. Five days after invasion, titanium implants were inserted in proximal tibia. Five, 10, and 20 days after implant placement, tibiae were collected. After taking micro-CT and performing a torque test, the tibiae were decalcified and 8-μm-thick sections were prepared. Specimens were stained with hematoxylin and eosin. Results. Micro-CT images, removal torque values, and histomorphometric analysis data demonstrated a significantly accelerated bone formation in the laser group earlier in the healing process. Conclusion. The use of laser irradiation was effective in promoting bone formation and acquiring osseointegration of titanium implants inserted in rat tibia. LIBT may be suitable for use in implant therapy. PMID:22505900

  12. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Excitation of nuclear isomers by X rays from laser plasma

    NASA Astrophysics Data System (ADS)

    Andreev, Aleksandr A.; Platonov, Konstantin Yu; Rozhdestvenskii, Yu V.; Karpeshin, F.; Trzhaskovskaya, M. B.

    2010-06-01

    The possibility of obtaining isomer nuclei is studied by the example of the molybdenum isomer 93Mo upon irradiation of a niobium 93Nb target by ~50-J, 100-fs laser pulses. It is shown that the modern laser technique allows production of isomer nuclei by accelerated protons and radiative de-excitation of isomer nuclear states by thermal or line X-rays from laser plasma.

  13. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Ion acceleration by ultrahigh-power ultrashort laser pulses

    NASA Astrophysics Data System (ADS)

    Brantov, A. V.; Bychenkov, V. Yu; Rozmus, V.

    2007-09-01

    Two- and three-dimensional numerical simulations of fast-ion generation under ultrashort high-power laser pulse irradiation of stratified targets of different density and thickness are performed by the 'particle-in-cell' technique. The intent of these simulations was to determine the optimal target for maximising the ion energy for a given energy of the laser pulse. The simulations were carried out for the presently highest laser radiation intensities.

  14. Properties of laser radiation scattering by a laser-induced spark plasma revisited after 40 years

    SciTech Connect

    Malyutin, A A

    2008-05-31

    Experimental studies of a laser-induced spark produced in air by 1.05-{mu}m, 100-ns pulses with spatial TEM{sub 00}, TEM{sub 01} and TEM{sub 02} modes are described. It is found that when the spark is observed at an angle of 90{sup 0} to the laser beam axis, the scattered radiation has the maximal intensity outside the beam waist. The intensity ratio of the scattered laser radiation for two orthogonal polarisations is {approx}100, and the spatial structures of their depolarisation considerably differ. These properties are explained by using a model of the Fresnel reflection from the spherical front of the plasma-undisturbed gas interface. (laser radiation scattering)

  15. Laser-Produced Plasmas and Radiation Sources.

    DTIC Science & Technology

    1980-01-31

    Vlases, H. Rutkowski, A. Hertzberg, A. Hoffman, L. Steinhauer, J. Dawson, D.R. Cohn, W. Halverson, B. Lax, J.D. Daugherty, J.E. Eninger , E.R. Pugh, T.K...Meeting, Albuquerque (October 1974). J.D. Daugherty, J.E. Eninger , D.R. Cohn, and W. Halverson, "Scaling of Laser Heated Plasmas Confined in Long Solenoids...Cohn, H.E. Eninger , W. Halverson, and D.J. Rose, "Stress, Dissipation, and Neutronics Constraints on ’fagnets for Laser-Solenoid Reactors," APS Plasma

  16. UV laser radiation-induced modifications and microstructuring of glass

    NASA Astrophysics Data System (ADS)

    Talkenberg, Marc; Kreutz, Ernst-Wolfgang; Horn, Alexander; Jacquorie, Michael; Poprawe, Reinhart

    2002-06-01

    Modifications and microstructures are generated on the surface and in the volume of silicate glasses using pulsed UV laser radiation of small pulse length. During the interaction of pulsed excimer laser radiation and frequency-trippled Nd:YAG laser radiation with intensities below the removal-threshold of the cerium- and silver-doped multi-component silicate glass absorption centers in the UV are induced. Subsequent thermal treatment and wet chemical etching results in crystallization of the laser-illuminated absorbing region and in the fabrication of microstructures on the surface. Processing of sodalime- and boro-silicate glass with pulsed ArF excimer laser radiation and frequency-doubled Nd:YAG laser radiation with intensities above the removal-threshold leads to microstructures including the generation of microcracks on the surface and in the bulk. The dynamics and the transmission of the expanding plasma and changes in the refractive index of the glass are investigated with speckle photography using the pump and probe method. The determination of plasma emission and crack generation is carried out using high speed and Nomarski photography. Morphological and chemical properties of the debris generated under defined processing gas atmospheres are investigated with REM, white light interferometry, XPS and EPMA. Induced absorption and changes of the crystalline- phase are probed using optical-spectroscopy and XRD as well REM. On the basis of these investigations the processes of the generation of induced absorption centers and crystallization on the one hand and the generation of cracks and debris on the other hand as well as the quality of the produced microstructures is discussed.

  17. CONTROL OF LASER RADIATION PARAMETERS: Non-isochronism of the radiation frequency of a solid-state laser with a homogeneously broadened gain line

    NASA Astrophysics Data System (ADS)

    Kravtsov, Nikolai V.; Lariontsev, E. G.

    2009-11-01

    The dependence of the radiation frequency of a solid-state laser on the laser radiation field amplitude is studied theoretically. It is shown the non-isochronism of the laser frequency appears only when the contribution of spontaneous emission to the generated resonator mode is taken into account and is manifested most strongly at small excesses of the pump over the threshold.

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

    PubMed

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

    2014-08-07

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

  19. Direct quantitative comparison of molecular responses in photodamaged human skin to fractionated and fully ablative carbon dioxide laser resurfacing.

    PubMed

    Orringer, Jeffrey S; Sachs, Dana L; Shao, Yuan; Hammerberg, Craig; Cui, Yilei; Voorhees, John J; Fisher, Gary J

    2012-10-01

    Fractionated ablative laser resurfacing has become a widely used treatment modality. Its clinical results are often found to approach those of traditional fully ablative laser resurfacing. To directly compare the molecular changes that result from fractionated and fully ablative carbon dioxide (CO(2)) laser resurfacing in photodamaged human skin. Photodamaged skin of 34 adult volunteers was focally treated at distinct sites with a fully ablative CO(2) laser and a fractionated CO(2) laser. Serial skin samples were obtained at baseline and several time points after treatment. Real-time reverse transcriptase polymerase chain reaction technology and immunohistochemistry were used to quantify molecular responses to each type of laser treatment. Fully ablative and fractionated CO(2) laser resurfacing induced significant dermal remodeling and collagen induction. After a single treatment, fractionated ablative laser resurfacing resulted in collagen induction that was approximately 40% to 50% as pronounced as that induced by fully ablative laser resurfacing. The fundamental cutaneous responses that result from fully ablative and fractionated carbon dioxide laser resurfacing are similar but differ in magnitude and duration, with the fully ablative procedure inducing relatively greater changes including more pronounced collagen induction. However, the molecular data reported here provide substantial support for fractionated ablative resurfacing as an effective treatment modality for improving skin texture. © 2012 by the American Society for Dermatologic Surgery, Inc. Published by Wiley Periodicals, Inc.

  20. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Polarisation properties of radiation of high-power industrial multitubular CO2 lasers

    NASA Astrophysics Data System (ADS)

    Galushkin, M. G.; Zabelin, A. M.; Zelenov, E. V.; Korotchenko, A. V.; Chernous, V. N.

    2003-12-01

    The polarisation of radiation of high-power industrial multitubular, diffusion-cooled CO2 lasers is studied. The conditions of the appearance of linear and elliptic polarisation and of polarisation instability are determined. The relation between the laser parameters and its polarisation characteristics is established.

  1. [Low-intensity laser radiation in preventive measures].

    PubMed

    Ushkova, I N; Nal'kova, N Yu; Chernushevich, N I; Popov, A V; Kochetova, O A

    2013-01-01

    Results of preventive measures introduction in 524 PC users, 98 jewelry polishers and 64 metallic ship hull assemblers are given. The use of preventive measures, based on low-intensity laser radiation, was shown to prevent development of visual overfatigue and occupational musculoskeletal system diseases.

  2. Undulator radiation driven by laser-wakefield accelerator electron beams

    NASA Astrophysics Data System (ADS)

    Wiggins, S. M.; Anania, M. P.; Welsh, G. H.; Brunetti, E.; Cipiccia, S.; Grant, P. A.; Reboredo, D.; Manahan, G.; Grant, D. W.; Jaroszynski, D. A.

    2015-05-01

    The Advanced Laser-Plasma High-Energy Accelerators towards X-rays (ALPHA-X) programme is developing laserplasma accelerators for the production of ultra-short electron bunches with subsequent generation of coherent, bright, short-wavelength radiation pulses. The new Scottish Centre for the Application of Plasma-based Accelerators (SCAPA) will develop a wide range of applications utilising such light sources. Electron bunches can be propagated through a magnetic undulator with the aim of generating fully coherent free-electron laser (FEL) radiation in the ultra-violet and Xrays spectral ranges. Demonstration experiments producing spontaneous undulator radiation have been conducted at visible and extreme ultra-violet wavelengths but it is an on-going challenge to generate and maintain electron bunches of sufficient quality in order to stimulate FEL behaviour. In the ALPHA-X beam line experiments, a Ti:sapphire femtosecond laser system with peak power 20 TW has been used to generate electron bunches of energy 80-150 MeV in a 2 mm gas jet laser-plasma wakefield accelerator and these bunches have been transported through a 100 period planar undulator. High peak brilliance, narrow band spontaneous radiation pulses in the vacuum ultra-violet wavelength range have been generated. Analysis is provided with respect to the magnetic quadrupole beam transport system and subsequent effect on beam emittance and duration. Requirements for coherent spontaneous emission and FEL operation are presented.

  3. Diffractive variable attenuator for femtosecond laser radiation control.

    PubMed

    Poleshchuk, Alexander G; Nasyrov, Ruslan K; Cherkashin, Vadim V; Dubov, Mykhaylo V; Mezentsev, Vladimir M; Bennion, Ian

    2009-02-01

    We present a diffractive phase variable attenuator for femtosecond laser radiation control. It allows the control of beam power up to 0.75.10(13) W/cm(2) without introducing serious distortions in spectra and beam shape while it operates in zero order diffraction. The attenuator can operate with wavelengths from DUV to IR.

  4. Pulsed carbon dioxide laser for cartilage vaporization and subchondral bone perforation in horses. Part I: Technique and clinical results.

    PubMed

    Roth, J E; Nixon, A J; Gantz, V A; Meyer, D; Mohammed, H

    1991-01-01

    A carbon dioxide laser, used in a rapidly pulsed mode, was evaluated for intra-articular use in horses. Under arthroscopic guidance, a lensed 5 mm laser probe attached directly to a hand-held carbon dioxide laser was inserted into one intercarpal joint of eight horses. In four horses, a cartilage crater 1 cm in diameter was created to the level of the subchondral bone of the articular surface of the third carpal bone. In four horses, the laser was directed perpendicular to the articular surface of the third carpal bone and activated to penetrate the cartilage and subchondral bone. The intercarpal joint of the opposite carpus in each horse was subjected to arthroscopic examination and insertion of the laser probe for an equivalent time. The laser was not activated and these joints served as sham operated controls. The horses were evaluated clinically for 8 weeks, then euthanatized, and the joints were 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. The carbon dioxide laser is a useful intra-articular 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.

  5. Effect of carbon dioxide laser treatment on lesion progression in an intraoral model

    NASA Astrophysics Data System (ADS)

    Featherstone, John D. B.; Fried, Daniel; Gansky, Stuart A.; Stookey, George K.; Dunipace, Ann J.

    2001-04-01

    Previous studies have shown that pretreatment of dental enamel by specific carbon dioxide laser conditions inhibited subsequent progression of caries-like lesions in vitro. The aim of the present study was to use an intra-oral model to determine whether similar inhibition is observed in the human mouth. A cross over study with 23 subjects and three regimens was used. Pre-formed varies-like lesions were made in extracted human enamel and exposed intra-orally in partial dentures in each subject to A) placebo dentifrice and no laser treatment, B) placebo dentifrice following laser pretreatment, or C) sodium fluoride dentifrice and no laser treatment during each of three study periods. Samples were assessed by micro radiography to compare the mineral loss before and after each treatment and drive a net change in mineral value. Overall P was not significantly different form L but both P and L were different from F. For those subjects who demineralized in P, L and F were significantly better than P, with L showing an 84 percent inhibition of further demineralization, but no enhancement of demineralization.

  6. Ellipticity-dependent ionization/dissociation of carbon dioxide in strong laser fields

    NASA Astrophysics Data System (ADS)

    Zhang, Jun-Feng; Ma, Ri; Zuo, Wan-Long; Lv, Hang; Huang, Hong-Wei; Xu, Hai-Feng; Jin, Ming-Xing; Ding, Da-Jun

    2015-03-01

    Ionization and dissociation of linear triatomic molecules, carbon dioxide, are studied in 50-fs 800-nm strong laser fields using time-of-flight mass spectrometer. The yields of double charged ions and various fragment ions (CO+, On+, and Cn+ (n = 1, 2)) are measured as a function of ellipticity of laser polarization in the intensity range from 5.0 × 1013 W/cm2 to 6.0 × 1014 W/cm2. The results demonstrate that non-sequential double ionization, which is induced by laser-driven electron recollision, dominates double ionization of CO2 in the strong IR laser field with intensity lower than 2.0 × 1014 W/cm2. The electron recollision could also have contribution in strong-field multiple ionization and formation of fragments of CO2 molecules. The present study indicates that the intensity and ellipticity dependence of ions yields can be used to probe the complex dynamics of strong-field ionization/dissociation of polyatomic molecules. Project supported by the National Basic Research Program of China (Grant No. 2013CB922200) and the National Natural Science Foundation of China (Grant Nos. 11034003 and 11274140).

  7. Effect of a new carbon dioxide laser and fluoride on occlusal caries progression in dental enamel

    NASA Astrophysics Data System (ADS)

    Nobre dos Santos, Marines; Fried, Daniel; Rapozo-Hilo, Marcia L.; Featherstone, John D. B.

    2002-06-01

    The purpose of this study was to investigate the effect of a new TEA carbon dioxide (CO2) laser (.9.6 micrometers , 5-8 microsecond(s) pulse duration) combined with fluoride (F), on the inhibition of caries-like progression in occlusal surfaces in sound and demineralized enamel. Of 120 occlusal tooth surfaces (10 per group), 90 were partially demineralized in a 50% HAP/0.1 M Lactic acid/carbopol solution (pH 5.0). Samples were treated with/without the laser (2.0 j/cm2 or 3.0 J/cm2) and/or F (as APF). Caries-like progression was tested by 5 days of pH cycling. Results were assessed by cross-sectional quantitative microradiography. The percent inhibition of caries progression with laser and/or F ranged from 87-170%. This new TEA CO2 laser produced significant protective effect against lesion progression, and in combination with fluoride treatment lesion reversal occurred.

  8. Study of a three-dimensional axisymmetric-folded combination carbon dioxide laser with five discharge tubes

    NASA Astrophysics Data System (ADS)

    Feng, Tao; Li, Yude; Liu, Xiankui; Yan, Tingguang; Gao, Shan

    2009-06-01

    It has been experimentally demonstrated that a three-dimensional axisymmetric-folded combination carbon dioxide laser with five discharge tubes can offer a desired output power and good-quality light beam. The output laser has five sub-beams that start from a mutual point on the inside surface of the output plane lens. The collimation and convergence of the five sub-beams are obtained. In our results, the measured output laser power from a folded resonator was 37 W, and the total output of the laser was 76 W with 10% efficiency.

  9. The short pulse carbon dioxide laser versus the colorado needle tip with electrocautery for upper and lower eyelid blepharoplasty.

    PubMed

    Rokhsar, Cameron K; Ciocon, David H; Detweiler, Susan; Fitzpatrick, Richard E

    2008-02-01

    Various techniques for blepharoplasty have been described, including those performed with the assistance of the short pulse carbon dioxide laser and those performed with the assistance of the Colorado microdissection needle attached to an electrocautery unit. Although the superiority of the carbon dioxide laser to cold steel has been demonstrated for the performance of eyelid blepharoplasty, no studies have ever compared the carbon dioxide laser to the Colorado needle. This is a paired comparison study in which 12 healthy patients underwent bilateral blepharoplasty of their upper and/or lower eyelids by a single surgeon. For each patient, a short pulse carbon dioxide laser was used on one side, and a Colorado needle attached to an electrocautery unit was used on the other. Intraoperative times were recorded. At five post-operative visits patients were evaluated for post-operative healing parameters including edema, erythema, scar width, and bruising. Finally, excised tissue was assessed histologically for thermal damage. Comparing both techniques, no difference in patient or physician-measured parameters of healing were noted up to 1 month post-operatively. However, Colorado needle assisted blepharoplasty resulted in slightly shorter intraoperative times. It also resulted in less thermal damage on a histologic level, although these differences were not clinically significant. For the performance of blepharoplasty, the Colorado needle tip with electrocautery offers benefits equivalent to those of the short pulsed CO2 laser but has the advantage of shorter intraoperative times and lower cost.

  10. Conformation change of enzyme molecules in laser radiation field

    NASA Astrophysics Data System (ADS)

    Leshenyuk, N. S.; Prigun, M. V.; Apanasevitsh, E. E.; Kruglik, G. S.

    2007-06-01

    As a result of an analysis of macromolecules properties in the coherent optical radiation field and with allowance for the experimentally obtained unique data on the interaction of lazer radiation with biomolecules (dependence of the interaction efficiency on the coherence length, presence of the effect in the spectra region far from the absorption band), a mechanism of wave interaction is developed. Using this mathematical model, the calculations of a change in the macromolecules oscillatory energy in the coherent radiation field are performed. It is shown that the increase of macromolecules oscillatory energy depends strongly on the coherence length of radiation. On exposure to noncoherent radiation, the biomolecules oscillatory energy practically does not change, whereas on exposure to laser radiation (coherence length ~3 cm), energy of oscillations of atoms increases by an order of 2÷4, which results in a change in the conformation of biomolecules and activity of enzymes. Recently a lot of data are received concerning the change of lysosomal enzymes activity in blood plasma under action of laser radiation.

  11. Mathematical simulation of the amplification of 1790-nm laser radiation in a nuclear-excited He – Ar plasma containing nanoclusters of uranium compounds

    SciTech Connect

    Kosarev, V A; Kuznetsova, E E

    2014-02-28

    The possibility of applying dusty active media in nuclearpumped lasers has been considered. The amplification of 1790-nm radiation in a nuclear-excited dusty He – Ar plasma is studied by mathematical simulation. The influence of nanoclusters on the component composition of the medium and the kinetics of the processes occurring in it is analysed using a specially developed kinetic model, including 72 components and more than 400 reactions. An analysis of the results indicates that amplification can in principle be implemented in an active laser He – Ar medium containing 10-nm nanoclusters of metallic uranium and uranium dioxide. (lasers)

  12. Carbon dioxide and climate: The effects of water transport in radiative-convective models

    NASA Astrophysics Data System (ADS)

    Hummel, John R.; Reck, Ruth A.

    1981-12-01

    Considerable attention is being focused on the possible climatic effects resulting from increases in the concentration of atmospheric carbon dioxide. In calculating CO2 influence on the thermal structure of the atmosphere, the role of clouds is critically important. Not only are the cloud properties, such as amount, numbers of clouds, altitudes, and optical properties important but also whether or not these properties are fixed or coupled to model temperatures. The transport of water vapor determines whether or not a region has clouds, the cloud properites, and the water vapor profiles appropriate for clear and cloudy skies. Results are presented of the change in surface temperature with changes in carbon dioxide content for two radiative-convective models with three different cloud coverages. We used (1) the Manabe-Wetherald radiative-convective model in which three clouds with fixed pressures, thicknesses, and optical properties and a single water vapor profile are inputed and (2) the Hummel-Kuhn model, which couples radiative heating, convection, and water vapor transport in order to calculate locations and thicknesses. The Hummel-Kuhn model yields temperature increases for doubled CO2 larger than the Manabe-Wetherald model for various assumed total cloud cover amounts. For assumed standard cloud cover amounts the Hummel-Kuhn estimate is 20% larger than the Manabe-Wetherald estimate. For reduced and enhanced cloud cover amounts the Hummel-Kuhn estimates are 37% and 17% larger, respectively. The calculated cloud locations and thicknesses did not change in the calculations; therefore the increased sensitivity in the Hummel-Kuhn model is due to the larger water vapor amounts in the Hummel-Kuhn model and the added infrared absorption by the water vapor dimer.

  13. A clinical and histologic comparison of electrosurgical and carbon dioxide laser peels.

    PubMed

    Acland, K M; Calonje, E; Seed, P T; Stat, C; Barlow, R J

    2001-03-01

    A radiofrequency-controlled electrosurgical device (ESD) has been adapted for skin peeling. A high-voltage, low-amperage current converts an irrigant into an ionized vapor, causing molecular dissociation and superficial damage in adjacent tissue. We compared the clinical and histologic effects of a scanning carbon dioxide (CO(2)) laser (ESC/Sharplan 40C) and the ESD (Visage Cosmetic Surgery System, Arthrocare). This study was a matched clinical trial involving 9 subjects. Two strips (2 x 1 cm) of skin on the temple were alternately assigned to receive 2 passes with either the CO(2) laser (Silktouch mode, 260 handpiece, fluence 15 J/cm(2), 10 mm(2)) or the ESD (125 V = setting 4, 5 mm handpiece). Strips were wiped with moist gauze after the first pass, and 4-mm punch biopsy specimens were taken immediately and after 3 months. Clinical assessment of re-epithelialization, erythema, and hyperpigmentation was made at 1, 2, 4, and 12 weeks. Median erythema scores were significantly greater in skin treated with the CO(2) laser. Histologic examination showed greater epidermal loss and a significantly thicker zone of underlying thermal damage (average difference, 63 microm; 95% confidence interval, 40-87; P =.0002) in skin treated with the CO(2) laser compared with skin treated with the ESD. After 3 months, a band of superficial dermal fibrosis was thicker in skin treated with the CO(2) laser (average difference, 170 microm; 95% confidence interval, 69-271; P =.0075). Two passes with the ESD elicited a more superficial skin peel than the CO(2) laser. Despite minimal thermal damage, superficial dermal fibrosis was seen at 3 months in skin treated with the ESD.

  14. Femtosecond laser induced periodic nanostructures on titanium dioxide film for improving biocompatibility

    NASA Astrophysics Data System (ADS)

    Shinonaga, T.; Horiguchi, N.; Tsukamoto, M.; Nagai, A.; Yamashita, K.; Hanawa, T.; Matsushita, N.; Guoqiang, X.; Abe, N.

    2013-03-01

    Periodic nanostructures formation on Titanium dioxide (TiO2) film by scanning of femtosecond laser beam spot at fundamental and second harmonic wave is reported. Titanium (Ti) is one of the most widely used for biomaterials, because of its excellent anti-corrosion and high mechanical properties. However, Ti implant is typically artificial materials and has no biofunction. Hence, it is necessary for improving the bioactivity of Ti. Recently, coating of TiO2 film on Ti plate surface is useful methods to improve biocompatibility of Ti plate. Then, if periodic nanostructures were formed on the film surface, cell spreading might be controlled at one direction. We propose periodic nanostructures formation on TiO2 film by femtosecond laser irradiation. Cell spread could be controlled along the grooves of periodic nanostructures. In the experiments, the film was formed on Ti plate with an aerosol beam. A commercial femtosecond Ti : sapphire laser system was employed in our experiments. Periodic nanostructures, lying perpendicular to the laser electric field polarization vector, were formed on the film at fundamental and second harmonic wave. Periodic nanostructures were also produced on Ti plate with femtosecond laser. The period of periodic nanostructures on the film was much shorter than that on Ti plate. By cell test, there was a region of cell spreading along the grooves of periodic nanostructures on the film formed with femtosecond laser at fundamental wave. On bare film surface, cell spreading was observed at all direction. These results suggest that direction of cell spread could be controlled by periodic nanostructures formation on the film.

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

    PubMed

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

    2010-01-01

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

  16. Laser sources in dentistry and radiation safety regulations

    NASA Astrophysics Data System (ADS)

    De Luca, D.; Gaeta, G. M.; Lepore, M.

    2007-02-01

    Nowadays laser sources are largely adopted in dentistry due to their unique properties making them good candidates to substitute traditional scalpel and conventional diamond bur in the surgery of the soft and hard oral tissue, respectively. The large use of laser sources outside the research laboratories without the need of highly specialized personnel can ask for a widespread knowledge of safety issues related to this kind of equipment. The main hazard of accidental exposures regards eyes injury but increasing the power of the laser beam also skin can be involved. Safety legislations in Europe and U.S.A. take into account non ionizing radiations and laser radiation for the hazards for the health deriving from physical agents. Laser safety standards introduce 3 useful parameters for hazard characterization: "Accessible Emission Limit" (AEL), "Maximum Permissible Exposure" (MPE) and "Nominal Ocular Hazard Distance" (NOHD). We measured the MPE and NOHD for Er:YAG and other laser sources currently adopted in dentistry and we compared our results with data elaborated from standards in order to single out safe and comfortable working conditions. In fact an experimental assessment of the hazard parameters and the comparison with those of reference from safety standards turns out to be useful in order to estimate the residual hazard that can be still present after applying all the engineering protection and administrative rules.

  17. Photo-Thermally Induced Current Switching in Vanadium-Dioxide-Based Devices Using CO2 Laser Pumping.

    PubMed

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

    2015-11-01

    By utilizing a CO2 laser as an illumination light source for triggering, we demonstrated bidirectional laser triggering in a two-terminal planar device based on a highly resistive vanadium dioxide (VO2) thin film. Bidirectional laser triggering between 0 and 10 mA was realized by switching the CO2 laser whose focused beam illuminated the VO2 film, and transient responses of laser-triggered devices were investigated when periodical laser pulses excited the VO2-based device at a variety of pulse widths and repetition rates. A switching contrast between off- and on-state currents was evaluated as -3333, and the rising and falling times were measured as -39 and -21 ms in the transient responses obtained by using periodic laser pulses with a pulse width of 100 ms, respectively.

  18. Optimization of THz Radiation Generation from a Laser Wakefield Accelerator

    SciTech Connect

    Plateau, G. R.; Matlis, N. H.; Toth, C.; Geddes, C. G. R.; Schroeder, C. B.; Tilborg, J. van; Albert, O.; Esarey, E.; Leemans, W. P.

    2009-01-22

    Ultrashort terahertz pulses with energies in the {mu}J range can be generated with laser wakefield accelerators (LWFA), which are novel, compact accelerators that produce ultrashort electron bunches with energies up to 1 GeV and energy spreads of a few-percent. Laser pulses interacting with a plasma create accelerated electrons which upon exiting the plasma emit terahertz pulses via transition radiation. Because these electron bunches are ultrashort (<50 fs), they can radiate coherently (coherent transition radiation--CTR) in a wide bandwidth ({approx}1-10 THz) yielding high intensity terahertz pulses. In addition to providing a non-invasive bunch-length diagnostic and thus feedback for the LWFA, these high peak power THz pulses are suitable for high field (MV/cm) pump-probe experiments. Here we present energy-based measurements using a Golay cell and an electro-optic technique which were used to characterize these THz pulses.

  19. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Low-threshold generation of harmonics and hard x radiation in a laser plasma. 1. Single-peak generation

    NASA Astrophysics Data System (ADS)

    Apollonov, V. V.; Derzhavin, S. I.; Kazakov, K. Kh

    1993-02-01

    A source of hard x radiation based on a laser plasma has been studied under conditions such that parametric instabilities are driven in the plasma at low intensities of the pump radiation (below 10 GW/cm2). A qualitative interpretation of the observed effects is offered.

  20. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Temporal and thermodynamic characteristics of plasma formation

    NASA Astrophysics Data System (ADS)

    Ignatavichyus, M. V.; Kazakyavichyus, É.; Orshevski, G.; Danyunas, V.

    1991-11-01

    An investigation was made of plasma formation accompanying the interaction with aluminum, iron, and VK-6 alloy targets of nanosecond radiation from a YAG:Nd3+ laser (Emax = 50 mJ, τ = 3-8 ns). The duration of the plasma formation process depended weakly on the laser radiation parameters [the power density was varied in the range 1-3 GW/cm2, the pulse rise time in the range 2-8 ns, or the rate of rise of the power density in the range (1-8) × 108 W · cm - 2 · ns -1]. A study was made of the establishment of a local thermodynamic equilibrium in a plasma jet excited by radiation from nanosecond and picosecond (E = 30 mJ, τ = 40 ps) lasers. The maximum of the luminescence from an aluminum plasma excited by picosecond laser radiation was found to correspond to a local thermodynamic equilibrium. A local thermodynamic equilibrium could be absent in the case of excitation by nanosecond laser radiation.

  1. Facet joint laser radiation: tissue effects of a new clinical laser application

    NASA Astrophysics Data System (ADS)

    Werkmann, Klaus; Thal, Dietmar R.

    1996-01-01

    Chronic unilateral and bilateral back pain with pseudoradicular symptoms, is a common clinical syndrome, which in many cases can be related to the facet joint syndrome. The pain is caused by mechanical affection of synovial and capsular nerve terminals. Therefore, current therapeutical attempts including physical therapy, intra-articular injection of local anesthetics and steroids and thermocoagulation of the facet joint with a thermocoagulator, are performed. We confirmed laser coagulation of the facet joint. Porcine cadaveric spines were treated immediately after death by intra-articular facet joint laser radiation. With the pulsed Nd:YAG laser (1064 nm) altogether 600 J were applied in three different places 4 mm apart at the top of the facet joint. The results showed that facet joint laser radiation leads to a small (about 1 - 2 mm diameter) lesion restricted to the facet joint cavity and its synovia. Histologically, we found a central carbonization zone and necrosis, including almost the whole cartilage and approximately 0.2 mm of the adjacent bone. These changes are similar to Nd:Yag-laser applications in other skeletal regions. It is suggested that these changes may lead to facet joint denervation by coagulation of the synovial nerve terminals. Cicatration of the laser lesion might cause ankylosis of this joint. In sum, facet joint laser radiation could be an alternative therapeutical tool for lower back pain of the facet joint syndrome type. Therefore, future clinical application of this technique seems to be very promising.

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

    NASA Astrophysics Data System (ADS)

    Humphries, Seth David

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

  3. Fractional carbon-dioxide (CO2) laser-assisted topical therapy for the treatment of onychomycosis.

    PubMed

    Bhatta, Anil Kumar; Keyal, Uma; Huang, Xin; Zhao, Jing Jun

    2016-05-01

    Inability of topical medications to penetrate via nail plate brings a great challenge to clinicians in treating onychomycosis. Furthermore, oral medications are not appropriate for all patients because of drug interactions, adverse effects, and contraindications. We sought to evaluate the clinical efficacy of fractional carbon-dioxide laser-assisted topical therapy for onychomycosis. In total, 75 patients with 356 onychomycotic nails confirmed by mycologic examination were included in this study. All the affected nails received 3 sessions of laser therapy at 4-week intervals and once-daily application of terbinafine cream for 3 months. In all, 94.66% and 92% of the treated patients were potassium hydroxide and culture negative, respectively, after 3 months of treatment. However, only 84% and 80% were potassium hydroxide and culture negative, respectively, at 6 months of follow-up. Using Scoring Clinical Index for Onychomycosis electronic calculator, 73.33% of the patients scored higher than 6 and 26.66% of the patients scored 6 or less. Those who scored more than 6 were evaluated clinically and 98.18% of them showed response to treatment at 3 months and 78.18% of them at 6 months of follow-up. Lack of control group and short duration of follow-up are limitations. Fractional carbon-dioxide laser therapy combined with topical antifungal was found to be effective in the treatment of onychomycosis. However, randomized clinical studies are needed before it can be widely used in clinics. Copyright © 2015 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.

  4. INTERACTION OF LASER RADIATION WITH MATTER: Estimates of phase-transition heats in steels and ceramics heated by laser radiation

    NASA Astrophysics Data System (ADS)

    Tsar'kova, O. G.; Garnov, Sergei V.

    2003-08-01

    Measurements of the high-temperature dependences of the heat capacity of solids heated by high-power laser radiation and the model of formation of structural point defects (vacancies) are used to estimate the heats of sublimation, evaporation and melting, as well as enthalpy of phase transformations for modern processing of steels and ceramics.

  5. 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.

  6. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Formation of amplified spontaneous radiation in an expanding laser plasma allowing for refraction

    NASA Astrophysics Data System (ADS)

    Gulov, A. V.; Derzhiev, V. I.; Zhidkov, A. G.; Terskikh, A. O.; Yakovlenko, Sergei I.

    1990-06-01

    Calculations are made of the divergence of amplified spontaneous radiation in a laser plasma allowing for refraction by free electrons. An analysis is made of the divergence of the radiation generated due to a 3p→3s' transition in neon-like ions. Calculations are made of the divergence of the radiation due to the 4→3 transition in the O VIII ion allowing for refraction during expansion of a Formvar plasma.

  7. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Low-threshold generation of harmonics and hard x radiation in a laser plasma. 2. Multipeak generation

    NASA Astrophysics Data System (ADS)

    Apollonov, V. V.; Derzhavin, S. I.; Kazakov, K. Kh

    1993-02-01

    The conditions for the generation of hard x radiation with a multipeak structure in a plasma pumped by a long pulse from a free-running CO2 laser at a low intensity (q≲10 GW/cm2) have been studied. This x-ray generation had been observed in a previous study by the present authors. It is shown that this generation of hard x radiation with a multipeak structure leads to a more than tenfold increase in the yield of hard x radiation per laser pulse, under optimum conditions. This increase results from the additional peaks in the x-ray signal. An explanation of this effect is proposed.

  8. Beam shaping of laser diode radiation by waveguides with arbitrary cladding geometry written with fs-laser radiation.

    PubMed

    Beckmann, Dennis; Schnitzler, Daniel; Schaefer, Dagmar; Gottmann, Jens; Kelbassa, Ingomar

    2011-12-05

    Waveguides with arbitrary cross sections are written in the volume of Al(2)O(3)-crystals using tightly focused femtosecond laser radiation. Utilizing a scanning system with large numerical aperture, complex cladding geometries are realized with a precision around 0.5 µm and a scanning speed up to 100 mm/s. Individual beam and mode shaping of laser diode radiation is demonstrated by varying the design of the waveguide cladding. The influence of the writing parameters on the waveguide properties are investigated resulting in a numerical aperture of the waveguides in the range of 0.1. This direct laser writing technique enables optical devices which could possibly replace bulky beam shaping setups with an integrated solution.

  9. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Transient laser-induced thermochemical processes on metal surfaces and their visualisation with a laser image amplifier

    NASA Astrophysics Data System (ADS)

    Prokoshev, V. G.; Galkin, A. F.; Klimovskii, Ivan I.; Danilov, S. Yu; Abramov, D. V.; Arakelyan, S. M.

    1998-04-01

    Laser oxidation of metals and alloys (steel, copper, brass, titanium, etc.) was investigated with a laser image amplifier based on a Cu laser making use of computer image processing. A method was developed for measuring the growth of an oxide film by recording the motion of interference minima (maxima) of the reflectivity for copper laser radiation when the oxide distribution was nonuniform. The results were compared with theoretical models.

  10. The role of vascular endothelial growth factor in fractional laser resurfacing with the carbon dioxide laser.

    PubMed

    Jiang, Xia; Ge, Hongmei; Zhou, Chuanqing; Chai, Xinyu; Ren, Qiu Shi

    2012-05-01

    The aim of this study was to analyze the role of vascular endothelial growth factor (VEGF) in mechanisms of cutaneous remodeling induced by fractional CO(2) laser treatment. The dorsal skin of Kunming mice was exposed to a single-pass fractional CO(2) laser treatment. Biopsies were taken 1 h, and 1, 3, 7, 14, 28 and 56 days after treatment. Skin samples VEGF expression was evaluated by immunohistochemistry and ELISA, fibroblasts by hematoxylin-eosin staining, and types I and III collagen by ELISA. Staining for VEGF was found in many types of cell including fibroblasts. The amount of VEGF in the skin of laser-treated areas had increased significantly compared to that in the control areas on days 1 and 3 (P < 0.05, P < 0.01, respectively), then decreased by day 7 after treatment and returned to the baseline level. The number of fibroblasts in the skin of the laser-treated areas had increased significantly compared to that in control areas on days 3, 7, 14, 28 and 56 after irradiation (P < 0.05, P < 0.01, P < 0.01, P < 0.01, P < 0.01, respectively). The amount of type I collagen was significantly higher in the skin of the laser-treated areas compared to that in control areas from day 28 to day 56 (P < 0.05, respectively), and type III collagen was significantly higher from day 3 to day 56 (P < 0.05, P < 0.05, P < 0.05, P < 0.05, P < 0.01, respectively). There was a positive correlation between the level of VEGF and fibroblast proliferation early stage after laser treatment (r = 0.853, P < 0.01), but there was no correlation after the first week (r = -0.124, P > 0.05). The amounts of type I and III collagen showed no significant correlations with the expression of VEGF in the late stages after laser treatment (r = 0.417, P > 0.05 and r = 0.340, P > 0.05, respectively). The results suggest that VEGF might be mainly involved in the early stages of wound healing, including the stages

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

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

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

  12. The Tea-Carbon Dioxide Laser as a Means of Generating Ultrasound in Solids

    NASA Astrophysics Data System (ADS)

    Taylor, Gregory Stuart

    1990-01-01

    Available from UMI in association with The British Library. Requires signed TDF. The aim of this thesis is to characterise the interaction between pulsed, high power, 10.6 mu m radiation and solids. The work is considered both in the general context of laser generation of ultrasound and specifically to gain a deeper understanding of the interaction between a laser supported plasma and a solid. The predominant experimental tools used are the homodyne Michelson interferometer and a range of electromagnetic acoustic transducers. To complement the ultrasonic data, various plasma inspection techniques, such as high speed, streak camera photography and reflection photometry, have been used to correlate the plasma properties with those of the ultrasonic transients. The work involving the characterisation of a laser supported plasma with a solid, which is based on previous experimental and theoretical analysis, gives an increased understanding of the plasma's ultrasonic generation mechanism. The ability to record the entire plasma-sample interaction, time history yields information of the internal dynamics of the plasma growth and shock wave generation. The interaction of the radiation with a solid is characterised in both the plasma breakdown and non-breakdown regimes by a wide ultrasonic source. The variation in source diameter enables the transition from a point to a near planar ultrasonic source to be studied. The resultant ultrasonic modifications are examined in terms of the wave structure and the directivity pattern. The wave structure is analysed in terms of existing wide source, bulk wave theories and extended to consider the effects on surface and Lamb waves. The directivity patterns of the longitudinal and shear waves are analysed in terms of top-hat and non -uniform source profiles, giving additional information into the radiation-solid interaction. The wide, one dimensional source analysis is continued to a two dimensional, extended ultrasonic source

  13. Radiation effects on the foaming of atactic polypropylene with supercritical carbon dioxide

    NASA Astrophysics Data System (ADS)

    Yang, Chenguang; Zhe, Xing; Zhang, Mingxing; Wang, Mouhua; Wu, Guozhong

    2017-02-01

    Atactic polypropylene (PP) samples with melt flow indices (MFI) of 7.0 g/10 min were irradiated and then foamed with supercritical carbon dioxide (scCO2). A detailed investigation was carried out to understand the effect of radiation on the scCO2 foaming of polypropylene. Variations in the molecular weight, branching degree, crystallinity, and melting and crystallization temperatures of irradiated PP were investigated. The cell diameter, cell density, volume expansion ratio and foaming rate were analyzed in detail under different conditions. It was found that the cell structure of PP foam became more uniform and the foaming temperature window increased to 10 °C. This compares favorably to the 4 °C observed with pristine atactic PP. The best cell morphology was observed at a dose of 30 kGy. The corresponding average diameter and cell density were 16.4 μ m and 5.7×107 cells/cm3, respectively.

  14. Treatment of recalcitrant warts with the carbon dioxide laser using an excision technique.

    PubMed

    Oni, Georgette; Mahaffey, Peter J

    2011-10-01

    Recalcitrant warts remain a challenging problem to treat, with considerable morbidity for patients. Our technique uses the carbon dioxide (CO2) laser as a bloodless scalpel to excise and treat recalcitrant warts. This paper reviews the results of patients with recalcitrant warts treated by the senior author using this technique. A retrospective case note review and questionnaire-based survey of patients treated by this technique. Seventy-one recalcitrant warts treated in 22 patients, all as day case procedures. A total of 54.5% of patients had complete remission after one treatment and the average length of follow-up was 71.5 months. Recurrence occurred on average 5.29 months following treatment. Of those patients, 90% were successfully retreated, giving an overall rate of 95.5%. In total, 46.7% of patients were left with scarring, but all felt this was acceptable given the benefits of the treatment, and 80.0% of patients would have the procedure again. Four patients had spontaneous regression of warts at other body sites not treated with the CO2 laser. This study illustrates the efficacy of our technique with a favourable outcome comparable to published studies. Recurrence occurred within 12 months; therefore, we would recommend this as a minimum follow-up period. In addition, the disappearance of warts at distant sites suggests that the effects of the CO2 laser therapy modulate the immune system, thereby extending it beyond simple excision or ablation.

  15. Evaluation of carbon dioxide laser therapy for benign tumors of the eyelid margin.

    PubMed

    Rentka, Aniko; Grygar, Jan; Nemes, Zoltan; Kemeny-Beke, Adam

    2017-09-02

    Eyelid margin tumors require special attention based on both anatomical and histological perspectives. Our aim in this study was to evaluate carbon dioxide (CO2) laser therapy for the treatment of eyelid margin tumors. Fifty-two patients with 55 eyelid margin tumors were included in this study. All tumors were removed with a CO2 laser, and histopathological evaluation was obtained in 52 cases. All patients were followed up for a mean period of 8.5 months (range 6 to 14 months). There were no bleedings in the intra- and postoperative period; the wounds were dry and reepithelized after 10-14 days and no recurrence occurred during follow-up period. Compared to the surrounding tissue, the treated area was hypopigmented and maximum five eyelashes (average 2.5) were wasted during the procedure. We achieved complete patient and surgeon satisfaction with cosmetic and therapeutic results. CO2 laser treatment of eyelid margin is a safe and effective procedure; its cosmetic result is beneficial as it does not cause malposition of the eyelid or damage to the lacrimal drainage system if the tumor is located in its proximity.

  16. Peculiarities of the angular distribution of laser radiation intensity scattered by laser-spark plasma in air

    SciTech Connect

    Malyutin, A A; Podvyaznikov, V A; Chevokin, V K

    2010-02-28

    The spatiotemporal study of the diagram of laser radiation scattering by the laser-spark plasma produced by 3-ns and 50-ns pulses is performed. It is shown that radiation appearing outside the laser beam cone is scattered during the first one - two nanoseconds after the air breakdown, when the spark plasma is located in the vicinity of the laser beam waist and has a shape close to spherical.

  17. Guided Radiation Beams in Free Electron Lasers.

    DTIC Science & Technology

    1988-05-19

    the electron beam in an FEL that the radiation beam will remain guided. 0 20 II. Refractive Index Associated with FELs In our model, the vector ...eIAw/ymOc(exp(ikwz) + c.c.) ex/2 , is the wiggle velocity, y is the Lorentz factor, Aw is the vector potential amplitude of the planar wiggler...Balboa Avenue Palo Alto, CA 94303 San Diego, CA 92123 38 Dr. S. Krinsky Nat. Synchrotron Light Source Dr. Michael Lavan Brookhaven National Laboratory U.S

  18. Control of Hazards to Health From Laser Radiation

    DTIC Science & Technology

    2006-01-01

    generated air contaminants 8–5 77 Collateral and plasma radiation 8–6 77 Fire hazards 8–7 78 Explosion hazards 8–8 78 Compressed gases 8–9 78 Laser...elliptical beams B–11 143 Beam diameter versus range B–12 144 Atmospheric attenuation B–13 145 Laser range equation B–14 145 Nominal ocular...mathematical symbols 111 B–2 Atmospherically corrected values of nominal ocular hazard distance (NOHD) in kilometers, assuming µ = 0.05 km-1, when

  19. TEA HF laser with a high specific radiation energy

    NASA Astrophysics Data System (ADS)

    Puchikin, A. V.; Andreev, M. V.; Losev, V. F.; Panchenko, Yu. N.

    2017-01-01

    Results of experimental studies of the chemical HF laser with a non-chain reaction are presented. The possibility of the total laser efficiency of 5 % is shown when a traditional C-to-C pumping circuit with the charging voltage of 20-24 kV is used. It is experimentally shown that the specific radiation output energy of 21 J/l is reached at the specific pump energy of 350 J/l in SF6/H2 = 14/1 mixture at the total pressure of 0.27 bar.

  20. Interaction of high-intensity laser radiation with metals.

    NASA Technical Reports Server (NTRS)

    Linlor, W. I.

    1971-01-01

    The interaction is characterized by the production of plasma, within which the primary absorption occurs. Absorption of laser radiation by a plasma may occur by several processes. The absorption process called 'inverse bremsstrahlung' is discussed. The interaction of a laser beam with the plasma produced from a thick metal target was studied. The results of the measurements of the ion kinetic energies are presented in a graph. In addition to measurements with thick targets, information was also obtained with a thin foil of gold.

  1. Modelling of intense line radiation from laser-produced plasmas

    SciTech Connect

    Lee, Yim T.; Gee, M.

    1990-04-01

    In this paper, we discuss modelling of Lyman-{alpha} (i.e. Ly-{alpha}) radiation emitted from laser-produced plasmas. We are interested in the application of one of these line radiations to pump a transition of an ion in a different plasma spatially separated from the emitting source. The interest is in perturbing the plasma rather than just probing it as in some backlighting experiments. As a result of pumping, the populations of certain excited levels are inverted. The resulting gain coefficients depend strongly on the population inversion density which in turn depends on the brightness of the pump radiation. As a result, we must produce an intense bright radiation source. In addition, to pump a transition effectively, we also need a pump line with a width larger than the mismatch of the resonance since the widths of the pumped transitions are rather narrow

  2. Investigation of Ultrafast Laser-Driven Radiative Blast Waves

    SciTech Connect

    Edwards, M. J.; MacKinnon, A. J.; Zweiback, J.; Shigemori, K.; Ryutov, D.; Rubenchik, A. M.; Keilty, K. A.; Liang, E.; Remington, B. A.; Ditmire, T.

    2001-08-20

    We have examined the evolution of cylindrically symmetric blast waves produced by the deposition of femtosecond laser pulses in gas jets. In high-Z gases radiative effects become important. We observe the production of an ionization precursor ahead of the shock front and deceleration parameters below the adiabatic value of 1/2 (for a cylinder), an effect expected when the blast wave loses energy by radiative cooling. Despite significant radiative cooling, the blast waves do not appear to develop thin shell instabilities expected for strongly radiative waves. This is believed to be due to the stabilizing effect of a relatively thick blast wave shell resulting in part from electron thermal conduction effects.

  3. Dynamic optical limiting experiments on vanadium dioxide and vanadium pentoxide thin films irradiated by a laser beam.

    PubMed

    Wang, Weiping; Luo, Yongquan; Zhang, Dayong; Luo, Fei

    2006-05-10

    Vanadium dioxide (VO2) and vanadium pentoxide (V2O5) thin films are irradiated by a near-infrared continuous-wave laser beam and the dynamic optical limiting performance is measured. The temperature varying with time of the films induced by a laser beam is also recorded by an IR thermal sensor. Under the irradiation of a laser beam with an intensity of 255 W/cm2 and a spot diameter of 2 mm, the laser beam transmittance of the VO2 film decreases from 47% before phase transition to 28% after phase transition, and the response time is approximately 200 ms; the laser beam transmittance of the V2O5 film decreases from 51% before phase transition to 24% after phase transition, and the response time is approximately 40 ms. The optical limiting is realized by this laser heating-induced phase transition.

  4. Dynamic optical limiting experiments on vanadium dioxide and vanadium pentoxide thin films irradiated by a laser beam

    SciTech Connect

    Wang Weiping; Luo Yongquan; Zhang Dayong; Luo Fei

    2006-05-10

    Vanadium dioxide (VO2) and vanadium pentoxide (V2O5) thin films are irradiated by a near-infrared continuous-wave laser beam and the dynamic optical limiting performance is measured. The temperature varying with time of the films induced by a laser beam is also recorded by an IR thermal sensor. Under the irradiation of a laser beam with an intensity of 255 W/cm2 and a spot diameter of 2 mm, the laser beam transmittance of the VO2 film decreases from 47% before phase transition to 28% after phase transition, and the response time is {approx}200 ms; the laser beam transmittance of the V2O5 film decreases from 51% before phase transition to 24% after phase transition, and the response time is {approx}40 ms. The optical limiting is realized by this laser heating-induced phase transition.

  5. EFFECTS OF LASER RADIATION ON MATTER: Influence of the ambient air pressure on short-wavelength radiation from a laser plasma

    NASA Astrophysics Data System (ADS)

    Golovin, A. F.; Zemtsov, S. S.; Fedyushin, B. T.

    1991-12-01

    A detailed experimental investigation was made of the radiation from a plasma created on an aluminum target by a pulsed CO2 laser at different ambient gas pressures. Measurements were made of the energy and angular distribution of the radiation and of the efficiency of conversion of laser energy into reemitted plasma radiation. The intensity of this radiation was found to exhibit pressure-dependent pulsations. The maximum reflection of the laser radiation from the plasma was recorded at a pressure of ~ 40 Torr. An interpretation is given of the experimental data.

  6. Analysis of metal surfaces coated with europium-doped titanium dioxide by laser induced breakdown spectroscopy.

    PubMed

    Głogocka, Daria; Noculak, Agnieszka; Pucińska, Joanna; Jopek, Wojciech; Podbielska, Halina; Langner, Marek; Przybyło, Magdalena

    2015-01-01

    The surface passivation with titanium sol-gel coatings is a frequently used technique to control the adsorption of selected biological macromolecules and to reduce the exposure of the bulk material to biological matter. Due to the increasing number of new coating-preparation methods and new gel compositions with various types of additives, the quality and homogeneity determination of the surface covering is a critical factor affecting performance of any implanted material. While coating thickness is easy to determine, the homogeneity of the surface distribution of coating materials requires more elaborate methodologies. In the paper, the laser induced breakdown spectroscopy (LIBS) based method, capable to quantitate the homogeneity and uniformity of the europium in titanium dioxide sol-gel coatings on stainless steel surfaces prepared with two different procedures: spin-coating and dip-coating, is presented. The emission intensity of titanium has been used to determine the coating thickness whereas the relative values of europium and titanium emission intensities provide data on the coating homogeneity. The obtained results show that the spin-coating technique provides better surface coverage with titanium dioxide. However, when the surface coating compositions were compared the dip-coating technique was more reliable.

  7. SCATTERING AND REFLECTION OF LASER RADIATION: Laser location of glitter points on a moving random surface

    NASA Astrophysics Data System (ADS)

    Grigor'ev, P. V.; Lomonosov, A. M.; Mikhalevich, Vladislav G.

    1998-05-01

    Coherent scattering of laser radiation by a moving random surface was investigated. Fluctuations of the scattered-radiation power were recorded in field experiments and were used to calculate the velocity of extremal points of the random surface. It was found that the distribution of velocities of these extremal points was close to a direction isotropic relative to the average velocity vector. The results obtained were compared with theoretical estimates for a Gaussian model of the surface.

  8. Laser dyes excited by high PRR Nd:YAG laser second-harmonic radiation

    NASA Astrophysics Data System (ADS)

    Soldatov, A. N.; Donin, V. I.; Jakovin, D. V.; Reimer, I. V.

    2008-01-01

    The lasing characteristics of red-emitting dyes in ethanol excited by Nd:YAG laser second-harmonic radiation are examined. The Nd:YAG laser was pumped by a diode matrix. The pump pulse repetition rates (PRRs) were 2.5 - 10 kHz and the pulse duration was 60 - 300 ns. The following dyes were evaluated: oxazine 17, DCM, DCM sp, and pyridine 1. The conversion efficiency for oxazine was 25 % without wavelength selection and 15 % with wavelength selection over the tuning range from 630 to 700 nm. The Nd:YAG and dye laser designs used are described elsewhere [1,2].

  9. CONTROL OF LASER RADIATION PARAMETERS: Theory of laser array phase locking by Fourier coupling

    NASA Astrophysics Data System (ADS)

    Vysotskii, D. V.; Napartovich, A. P.; Troshchieva, V. N.

    2007-04-01

    The type of coupling in a fibre laser array phase locked with the help of an external mirror located at the focal distance from the plane of output ends of individual lasers is studied analytically. The explicit expression is derived for the eigenvalue of the resonator and the restriction on the width of the tuning range in which laser array phase locking is preserved is determined. The influence of the spread in the optical lengths of fibres on the phase-locking efficiency is considered. The phase-locking efficiency is analysed for the spread of optical lengths of fibres considerably exceeding the radiation wavelength.

  10. Interaction of UV-Laser Radiation with Molecular Surface Films.

    DTIC Science & Technology

    2014-09-26

    the adsorption of the UV light in the metal and adsorbed molecular layers. The details of this theory were described in part in an article published...A-RI5S 59 INTERACTION OF UV-LRSER RADIATION WITH MOLECULAR / SURFACE FILRS(U) COLUMBIA UNJY NEW YORK DEPT OF ELECTRICAL ENGINEERING R N OSGOOD 91...TITLE 1I"’c’" d stru.’ty clam"’fic98onII"Interaction of UV- Laser Radiation with Molecular Surface Films" __________________ * 12. PERSONAL AUTHORIS

  11. Anomalous Radiative Trapping in Laser Fields of Extreme Intensity

    NASA Astrophysics Data System (ADS)

    Gonoskov, A.; Bashinov, A.; Gonoskov, I.; Harvey, C.; Ilderton, A.; Kim, A.; Marklund, M.; Mourou, G.; Sergeev, A.

    2014-07-01

    We demonstrate that charged particles in a sufficiently intense standing wave are compressed toward, and oscillate synchronously at, the antinodes of the electric field. We call this unusual behavior anomalous radiative trapping (ART). We show using dipole pulses, which offer a path to increased laser intensity, that ART opens up new possibilities for the generation of radiation and particle beams, both of which are high energy, directed, and collimated. ART also provides a mechanism for particle control in high-intensity quantum-electrodynamics experiments.

  12. Simulation of laser radiation effects on low dimensionality structures.

    PubMed

    Ramírez, Iliana María; Usma, Jorge Iván; López, Francisco Eugenio

    2013-05-01

    This paper presents a study on a system comprised of a low-dimensional structure (Ga1-xAlxAs and GaAs quantum well wire), an intense laser field and an applied magnetic field in axial direction, resulting in a modified structure by interaction with the laser field. A variation of the concentration of aluminum is considered. So, the characteristics of the semiconductor such as the effective mass and width of the forbidden band vary due to the aluminum concentration. The electronic Landé factor control by changing of both intensity and frequency of a laser field on cylindrical quantum well wire was also reported. We use the laser dressed approximation for the treated "quantum wire + laser" system as quantum wire in the absence of radiation but with parameter (electronic barrier height and electronic effective mass) renormalized by laser effects. We consider a magnetic field applied in the parallel direction of symmetric axis of the quantum well wire. We take into account non-parabolicity and anisotropy effects on the conduction band by Ogg-McCombe Hamiltonian.

  13. XUV radiation from gaseous nitrogen and argon target laser plasmas

    NASA Astrophysics Data System (ADS)

    Vrba, P.; Vrbová, M.; Brůža, P.; Pánek, D.; Krejčí, F.; Kroupa, M.; Jakůbek, J.

    2012-06-01

    Laser plasma created in gaseous target is studied as a source of radiation in the "water window" wavelength range. Plasma is created by focusing an 800 mJ/7 ns Nd:YAG laser pulse into the gas-puff target. Using nitrogen gas results in emission of an intense quasi-monochromatic radiation with the wavelength 2.88 nm, corresponding to the quantum transition 1s2p → 1s2 of helium -like nitrogen ion. The emission spectrum with argon target covers all the water window range. Laboratory and computer experiments have been performed for both target gases. The spatial distributions of emitted energy in the water window spectral range were compared. The total emitted energy with argon was one order higher than with nitrogen.

  14. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Doppler backscattered-signal diagnostics of laser-induced surface hydrodynamic processes

    NASA Astrophysics Data System (ADS)

    Gordienko, Vyacheslav M.; Kurochkin, Nikolay N.; Markov, V. N.; Panchenko, Vladislav Ya; Pogosov, G. A.; Chastukhin, E. M.

    1995-02-01

    A method is proposed for on-line monitoring of laser industrial processing. The method is based on optical heterodyne measurements of the Doppler backscattering signal generated in the interaction zone. Qualitative and quantitative information on hydrodynamic flows in the interaction zone can be obtained. A report is given of measurements, carried out at cw CO2 laser radiation intensities up to 1 kW cm-2, on the surfaces of a number of condensed materials irradiated in the monostatic interaction configuration.

  15. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Solidification structures on carbon materials surface-melted by repetitive laser pulses

    NASA Astrophysics Data System (ADS)

    Abramov, D. V.; Arakelyan, Sergei M.; Kutrovskaya, S. V.; Kucherik, A. O.; Prokoshev, V. G.

    2009-04-01

    The solidification morphology of carbon materials surface-melted by laser radiation at atmospheric pressure is studied. Electron microscopy results indicate that melt solidification is accompanied by the formation of surface microstructures, presumably due to the Rayleigh—Taylor instability in the molten carbon. The instability increment and surface tension coefficient of molten carbon are estimated, and the penetration of carbon vapour into the melt during one laser pulse is examined using numerical simulation.

  16. Strong terahertz radiation from air plasmas generated by an aperture-limited Gaussian pump laser beam

    SciTech Connect

    Peng Xiaoyu; Toncian, Toma; Jung, Ralph; Willi, Oswald; Li Chun; Li Yutong; Wang Weimin; Wang Shoujun; Liu Feng; Chen Min; Pukhov, Alexander; Sheng Zhengming; Zhang Jie

    2009-03-09

    Terahertz radiation generated by focusing the fundamental laser pulse and its second harmonic into ambient air strongly saturates with increasing pump laser energy. We demonstrate a simple method to control the Gaussian pump laser beam to improve the output of terahertz radiation with an adjustable aperture. With the optimal aperture-limited pump laser beams, the terahertz wave amplitudes can be enhanced by more than eight times depending on the pump laser parameters than those of aperture-free cases.

  17. Mechanisms of Retinal Damage from Chronic Laser Radiation.

    DTIC Science & Technology

    1981-07-01

    Laser Radiation Final Report T. Lawwill, M.D. and R.S. Crockett, Ph.D. July 1981 - Supported by U.S. Army Medical Research and Development Command Fort...Army Medical Research and Development Command July 1981 Fort Detrick, Frederick, MD 21701 ATTN: SGRD-RMS 13. NUMBEROFPAGES "- _158 14. MONITORING AGENCY...professor. ANIMAL USE STATEMENT In conducting the research described in this report, the investigator adhered to the "Guide for Laboratory Animal

  18. Absorption of resonance laser radiation in ultracold plasma

    NASA Astrophysics Data System (ADS)

    Shaparev, N. Ya

    2017-08-01

    The absorption of resonance laser radiation in an expanding ultracold plasma is considered. Initially the optical thickness τ0 of the medium decreases due to correlation heating of the ions; the subsequent lowering of τ0 is due to the variation of radial ion velocities. The expanding optically thick medium is shown to become transparent when the ratio between the particle expansion velocity at the sphere boundary and the thermal velocity exceeds the optical thickness τ0.

  19. Free electron laser based on the Smith Purcell radiation

    NASA Astrophysics Data System (ADS)

    Wang, Minghong; Liu, Pukun; Ge, Guangying; Dong, Ruixin

    2007-09-01

    A Smith-Purcell (S-P) free electron laser (FEL) composed of a metallic diffraction flat grating, an open cylindrical mirror cavity and a relativistic sheet electron beam with moderate energy, is presented. The characteristics of this device are studied by theoretical analysis, experimental measurements and particle-in-cell (PIC) simulation method. Results indicate that coherent radiation with output peak power up to 50 MW at millimeter wavelengths can be generated by using relativistic electron beam of moderate energy.

  20. Free electron laser based on the Smith — Purcell radiation

    NASA Astrophysics Data System (ADS)

    Wang, Ming-Hong; Xiao, Xiao-Guang; Yu, Hui-Shan; Meng, Xian-Zhu

    2006-11-01

    A Smith-Purcell (SP) free electron laser (FEL), composed of a metallic diffraction flat grating, an open cylindrical mirror cavity and a relativistic sheet electron beam with moderate energy, is presented. The characteristics of this device are studied by theoretical analysis, experimental measurements and particle-in-cell (PIC) simulation method. Results indicate that the coherent radiation with an output peak power up to 50 MW at millimeter wavelengths can be generated by using relativistic electron beam of moderate energy

  1. Interaction of Repetitively Pulsed High Energy Laser Radiation With Matter

    NASA Astrophysics Data System (ADS)

    Hugenschmidt, Manfred

    1986-10-01

    The paper is concerned with laser target interaction processes involving new methods of improving the overall energy balance. As expected theoretically, this can be achieved with high repetition rate pulsed lasers even for initially highly reflecting materials, such as metals. Experiments were performed by using a pulsed CO2 laser at mean powers up to 2 kW and repetition rates up to 100 Hz. The rates of temperature rise of aluminium for example were thereby increased by lore than a factor of 3 as compared to cw-radiation of comparable power density. Similar improvements were found for the overall absorptivities that were increased by this method by more than an order of magnitude.

  2. Photodestructive effect of IR laser radiation on the cornea

    NASA Astrophysics Data System (ADS)

    Podol'Tsev, A. S.; Zheltov, G. I.

    2007-01-01

    A mathematical model of the photodestructive effect of high-power IR laser radiation on cornea tissues is presented. The threshold energy exposure is calculated as a function of the wavelength and the laser pulse duration in the range 10-5-10-1 s under the assumption that the irreversible primary changes in the structure of tissues have a thermochemical nature. The adequacy of the model is supported by comparison of the results of calculations with a great body of experimental data available in the literature. The model is oriented for use in designing medical equipment (for example, for the refraction correction by the thermal keratoplasty method) and in refining the operating laser safety standards.

  3. Laser-heating-based active optics for synchrotron radiation applications.

    PubMed

    Yang, Fugui; Li, Ming; Gao, Lidan; Sheng, Weifan; Liu, Peng; Zhang, Xiaowei

    2016-06-15

    Active optics has attracted considerable interest from researchers in synchrotron radiation facilities because of its capacity for x-ray wavefront correction. Here, we report a novel and efficient technique for correcting or modulating a mirror surface profile based on laser-heating-induced thermal expansion. An experimental study of the characteristics of the surface thermal deformation response indicates that the power of a milliwatt laser yields a bump height as low as the subnanometer scale and that the variation of the spot size modulates the response function width effectively. In addition, the capacity of the laser-heating technique for free-form surface modulation is demonstrated via a one-dimensional surface correction experiment. The developed method is a promising new approach toward effective x-ray active optics coupled with at-wavelength metrology techniques.

  4. Optical Problems of Laser Radiation Transport in the LOTV Concept

    NASA Astrophysics Data System (ADS)

    Romanov, N. A.; Rodionov, A. Yu.; Sherstobitov, V. E.; Semenov, V. E.

    2004-03-01

    In the scope of the LOTV concept optical problems have been considered of a laser power transport from an airborne laser, flying at a 10-kilometer altitude, to a space ``tugboat'' with a laser propulsion engine (LPE), intended for payload orbital transfer from LEO to GEO. For a transmitter telescope size of 1-1.5 m the range of optimal sizes of a receiver collector as well as the range of optimal specific impulses of LPE have been determined for the radiation wavelength of 0.5 μ and 1 μ, and payloads of 3-5 t. The optimization was carried out by searching a trade-off between propellant mass saving and the orbit transfer time reduction.

  5. Regional Climate Response to Physiological Forcing of Carbon Dioxide in a Radiative-Convective Model

    NASA Astrophysics Data System (ADS)

    Cronin, T. W.; Prinn, R. G.

    2010-12-01

    Distinct from its radiative forcing of the climate system, elevated carbon dioxide is likely to result in reduced stomatal conductance and transpiration over land surfaces - a biophysical effect that has been termed physiological forcing. Most studies done to quantify the magnitude of the climate response to physiological forcing have utilized 3D Global Atmosphere-Land Models; recently several have concluded that amplification due to cloud feedbacks could cause the surface air warming over some land regions due to physiological forcing to be as large as 20-30% of the total warming due to doubled CO2. Here, we use versions of a Radiative-Convective model with a very simple representation of a land surface in single- and multiple- column modes to broadly investigate the effect of surface conductance to water vapor on the overlying atmosphere. Due to the uncertainty of the magnitude of physiological forcing for a given change in CO2, we model simple land surfaces of varying wetness, from saturated to nearly completely dry. Reduced surface conductance to water vapor (e.g. physiological forcing) generally results in warming of the near-surface atmosphere, but the warming is not necessarily monotonic, and is sensitive to assumptions about clouds. Implications of our results for estimation of regional climate response to physiological forcing are discussed.

  6. Molecular dynamics study of the bulk temperature effect on primary radiation damage in uranium dioxide

    NASA Astrophysics Data System (ADS)

    Martin, G.; Sabathier, C.; Wiktor, J.; Maillard, S.

    2015-06-01

    The effect of bulk temperature on the primary damage induced by a displacement cascade was investigated in uranium dioxide using classical molecular dynamics simulations. In this study, the Morelon potentials were used to model the middle-range interactions between the atoms that constitute the host matrix during the radiation events. Cascades were initiated by accelerating a uranium primary knock-on atom at 10keV inside a perfect UO2 lattice at a temperature between 700K and 1800K , a range which comprises in-pile temperatures of oxide fuels in light water reactors in standard operating conditions. Cascade overlap sequences were also simulated at 700K and 1400K in order to study the radiation damage accumulation in the oxide fuel. This study reveals the maximum damage level which the material can accommodate for decreases with the temperature. Furthermore the direct formation of vacancy clusters under irradiation is considerably slowed down above 1000K , notably during cascade overlap sequences.

  7. Laser system for testing radiation imaging detector circuits

    NASA Astrophysics Data System (ADS)

    Zubrzycka, Weronika; Kasinski, Krzysztof

    2015-09-01

    Performance and functionality of radiation imaging detector circuits in charge and position measurement systems need to meet tight requirements. It is therefore necessary to thoroughly test sensors as well as read-out electronics. The major disadvantages of using radioactive sources or particle beams for testing are high financial expenses and limited accessibility. As an alternative short pulses of well-focused laser beam are often used for preliminary tests. There are number of laser-based devices available on the market, but very often their applicability in this field is limited. This paper describes concept, design and validation of laser system for testing silicon sensor based radiation imaging detector circuits. The emphasis is put on keeping overall costs low while achieving all required goals: mobility, flexible parameters, remote control and possibility of carrying out automated tests. The main part of the developed device is an optical pick-up unit (OPU) used in optical disc drives. The hardware includes FPGA-controlled circuits for laser positioning in 2 dimensions (horizontal and vertical), precision timing (frequency and number) and amplitude (diode current) of short ns-scale (3.2 ns) light pulses. The system is controlled via USB interface by a dedicated LabVIEW-based application enabling full manual or semi-automated test procedures.

  8. Atmospheric transmission of CO2 laser radiation with application to laser Doppler systems

    NASA Technical Reports Server (NTRS)

    Murty, S. S. R.

    1975-01-01

    The molecular absorption coefficients of carbon dioxide, water vapor, and nitrous oxide are calculated at the P16, P18, P20, P22, and P24 lines of the CO2 laser for temperatures from 200 to 300 K and for pressures from 100 to 1100 mb. The temperature variation of the continuum absorption coefficient of water vapor is taken into account semi-empirically from Burch's data. The total absorption coefficient from the present calculations falls within + or - 20 percent of the results of McClatchey and Selby. The transmission loss which the CO2 pulsed laser Doppler system experiences was calculated for flight test conditions for the five P-lines. The total transmission loss is approximately 7 percent higher at the P16 line and 10 percent lower at the P24 line compared to the P20 line. Comparison of the CO2 laser with HF and DF laser transmission reveals the P2(8) line at 3.8 micrometers of the DF laser is much better from the transmission point of view for altitudes below 10 km.

  9. An Open-Path Tunable Diode Laser Sensor for Simultaneous Measurement of Methane And Carbon Dioxide

    NASA Astrophysics Data System (ADS)

    Bailey, D. M.; Adkins, E. M.; Wilson, E. L.; Miller, J. H. H.

    2014-12-01

    In a collaboration between NASA Goddard Space Flight Center, University of Alaska-Fairbanks, and George Washington University a study of the feedbacks to climate change caused by thawing permafrost has been initiated. An array of ground experiments at three unique permafrost sites will record permafrost depth, structure, meteorological data, and emissions of key greenhouse gases during a springtime permafrost thaw. Ground data will be linked to climate models and landscape structure from satellite imagery to gauge the magnitude of the feedbacks. GWU will deploy an open path instrument for independent measurement of ground-level carbon dioxide and methane. For several decades, our laboratory has developed diode laser absorption techniques using mid-infrared diode lasers as well as cavity- enhanced absorption measurements using near-infrared source. In the current project, we will continue to develop a system for open path measurements that builds on our past experience with deployment of multi-laser, multi species sensors. Spectral simulations suggest that at ambient levels of CO2 and CH4 (390 and 2 ppmV, respectively) we will observe extinction coefficients of ≈ 10-4 m-1 or ≈ 1% absorption over a 200 m path. Prior work in our laboratory suggests that a SNR in excess of 100 will be achievable at these absorption levels using wavelength-modulation techniques. Wavelength modulation spectroscopy entails applying a small amplitude modulation (on the order of the width of a spectral feature) to a laser's emitted frequency as it tunes through a spectrum. This is readily accomplished with near infrared telecom lasers whose frequency can be swept by varying the injection current going into the laser at fixed temperature. By sampling the detector's signal at a multiple of the modulation frequency, the resulting signal takes on the appearance of the spectrum's derivative. Typically, this is accomplished using a lock-in amplifier. To avoid the power burden of this

  10. Radiative forcing of carbon dioxide, methane, and nitrous oxide: A significant revision of the methane radiative forcing

    NASA Astrophysics Data System (ADS)

    Etminan, M.; Myhre, G.; Highwood, E. J.; Shine, K. P.

    2016-12-01

    New calculations of the radiative forcing (RF) are presented for the three main well-mixed greenhouse gases, methane, nitrous oxide, and carbon dioxide. Methane's RF is particularly impacted because of the inclusion of the shortwave forcing; the 1750-2011 RF is about 25% higher (increasing from 0.48 W m-2 to 0.61 W m-2) compared to the value in the Intergovernmental Panel on Climate Change (IPCC) 2013 assessment; the 100 year global warming potential is 14% higher than the IPCC value. We present new simplified expressions to calculate RF. Unlike previous expressions used by IPCC, the new ones include the overlap between CO2 and N2O; for N2O forcing, the CO2 overlap can be as important as the CH4 overlap. The 1750-2011 CO2 RF is within 1% of IPCC's value but is about 10% higher when CO2 amounts reach 2000 ppm, a value projected to be possible under the extended RCP8.5 scenario.

  11. Skin welding using pulsed laser radiation and a dye

    NASA Astrophysics Data System (ADS)

    Fried, Nathaniel M.; Walsh, Joseph T., Jr.

    1998-07-01

    Previous skin welding studies have used continuous wave (CW) delivery of radiation. However, heat diffusion during irradiation prevents strong welds from being achieved without creating large zones of thermal damage to surrounding tissue. This damage may prevent normal wound healing. Strong welds and minimal thermal damage can be achieved by introducing a dye and delivering the radiation in a pulsed mode. Two-cm-long, full-thickness incisions were made in guinea pig skin. India ink was used as an absorber, and egg white albumin was used as an adhesive. A 5-mm-diameter spot of CW, 1.06-micrometer Nd:YAG laser radiation was scanned over the weld site, producing 100 millisecond pulses. The cooling time between scans and number of scans was varied. Thermal damage zones were measured using a transmission polarizing microscope to identify birefringence changes in tissue. Tensile strengths were measured using a tensiometer. For pulsed welding and long cooling times, weld strengths of 2.4 kg/cm2 were measured, and thermal damage to the epidermis was limited to approximately 500 micrometers. With CW welding, comparable weld strengths resulted in approximately 2700 micrometer of thermal damage. CW laser radiation weld strengths were only 0.6 kg/cm2 when thermal damage in the epidermis was limited to approximately 500 micrometers.

  12. Indoor carbon dioxide monitoring with diode laser absorption at 2 μm

    NASA Astrophysics Data System (ADS)

    Li, Jinyi; Du, Zhenhui; Ma, Yiwen; Liu, Jingwang

    2015-05-01

    In order to investigate the variation of indoor carbon dioxide concentration and how it changes with human activities, a tunable diode laser absorption spectroscopy (TDLAS) system was used to monitor the indoor CO2 concentration. Based on Wavelength Modulation Spectroscopy double frequency detection (WMS-2f), the 2v1+v3 characteristic line (4991.26 cm-1) of CO2 was measured by a DFB laser. The measured concentration values were calibrated by means of a cell filled with reference gas. The results show that the daily average indoor CO2 concentrations is about 419ppm which is slightly higher than that of the outdoor and the changing range is between 380ppm and 510ppm in a day. The indoor CO2 concentration was influenced by the change of ventilation and indoor staff. The respiration of the indoor staff makes a greater impact on a relatively confined indoor CO2 concentration. The CO2 increasing rate is measured to be 80ppm/hour in the case of occupant density of 0.06 people/m3. Therefore, the staff crowded indoor should ventilate timely to prevent excessive CO2 causing people discomfort.

  13. Determination of laser-evaporated uranium dioxide by neutron activation analysis

    SciTech Connect

    Allred, R.

    1987-05-01

    Safety analyses of nuclear reactors require information about the loss of fuel which may occur at high temperatures. In this study, the surface of a uranium dioxide target was heated rapidly by a laser. The uranium surface was vaporized into a vacuum. The uranium bearing species condensed on a graphite disk placed in the pathway of the expanding uranium vapor. Scanning electron microscopy and X-ray analysis showed very little droplet ejection directly from the laser target surface. Neutron activation analysis was used to measure the amount of uranium deposited. The surface temperature was measured by a fast-response automatic optical pyrometer. The maximum surface temperature ranged from 2400 to 3700/sup 0/K. The Hertz-Langmuir formula, in conjunction with the measured surface temperature transient, was used to calculate the theoretical amount of uranium deposited. There was good agreement between theory and experiment above the melting point of 3120/sup 0/K. Below the melting point much more uranium was collected than was expected theoretically. This was attributed to oxidation of the surface. 29 refs., 16 figs., 7 tabs.

  14. Formation of nanostructures at the glass-carbon surface exposed to laser radiation

    SciTech Connect

    Abramov, D V; Gerke, M N; Kucherik, A O; Kutrovskaya, S V; Prokoshev, V G; Arakelyan, S M

    2007-11-30

    An experimental technique for obtaining nanostructures in the field of high-power laser radiation at the surface of carbon materials is developed. A specific feature of this technique is the formation of liquid carbon inside the region of laser action in the sample exposed to radiation in air at a pressure of {approx}1 atm. Several types of nanostructures (quasi-domains and nanopeaks) are detected in the laser cavern and beyond the range of laser action. Mechanisms of formation of such structures are proposed. The formation of quasi-domains is related to crystallisation of the melt. The nanopeak groups are formed outside the laser action region during the deposition of hot vapours of the material escaping from this region. The dependences of the variation in morphological properties of the nanostructures on the duration of laser action and the radii of typical cavern zones on the laser radiation power are obtained. (interaction of laser radiation with matter. laser plasma)

  15. [Infrared laser radiation in the treatment of low back pain syndrome].

    PubMed

    Mika, T; Orłow, H; Kuszelewski, Z

    1990-06-01

    The effectiveness was estimated of infrared laser radiation in the treatment of low back pain syndrome. The patients received irradiation from a semiconductor laser. The results were evaluated in 82 patients using a questionnaire of pain, taking into account its intensity, frequency, taking of analgesics, and the motor activity of the patient. The results suggest a favourable effect of infrared laser radiation on pain.

  16. Biological Effects of Laser Radiation. Volume II. Review of Our Studies on Biological Effects of Laser Radiation-1965-1971.

    DTIC Science & Technology

    1978-10-17

    days. Cell counts wer performed daily. Non-irradiated controls underwent lag phase for one day and exponential growth for 2 days leveling off on the...fourth day. The irradiated culture remained in lag phase for 2 days but then underwent exponential growth at a markedly higher rate than the controls...appears that while laser radiation prolonged the lag phase , it also stimulated mitotic activity. (1) Hardy, L.B., Hardy, F.S., Fine, S. and Sokal, J

  17. Counter-streaming radiative shock experiments on the Orion laser

    NASA Astrophysics Data System (ADS)

    Suzuki-Vidal, F.; Clayson, T.; Swadling, G. F.; Patankar, S.; Burdiak, G. C.; Lebedev, S. V.; Smith, R. A.; Stehle, C.; Chaulagain, U.; Singh, R. L.; Larour, J.; Kozlova, M.; Spindloe, C.; Foster, J.; Skidmore, J.; Gumbrell, E.; Graham, P.; Danson, C.

    2016-10-01

    The formation of radiative shocks, shocks in which the structure of density and temperature is affected by radiation from the shock-heated matter, is ubiquitous in many astrophysical scenarios. Experiments were performed at the Orion laser using a new target configuration that allows studying the formation of single and counter-streaming radiative shocks in gas-filled targets (Ne, Ar, Kr, Xe), with initial pressures 0.1-1 bar and a driver intensity of 6x1014 W/cm2 . The shocks propagate at velocities >60 km/s and were diagnosed with optical interferometry (streaked and time-resolved) and point-projection X-ray backlighting allowing to probe simultaneously the pre-shock radiative precursor and the shock front itself. Besides varying the extent of the radiative precursor the results show that different gases seem to have an effect on the shock front as evidenced by a number of spatial features. The results are compared with radiative hydrodynamics simulations in 1-D (HELIOS) and 2-D (NYM/PETRA). Supported by Orion Academic Access, the Royal Society, EPSRC, Labex PLAS@PAR. Currently at (2) LLNL, USA, (3) ELI, CZ, (4) First Light Fusion, UK.

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

    SciTech Connect

    Valderrama, B.; Henderson, H.B.; Gan, J.; Manuel, M.V.

    2015-04-01

    Atom probe tomography (APT) provides the ability to detect subnanometer chemical variations spatially, with high accuracy. However, it is known that compositional accuracy can be affected by experimental conditions. A study of the effect of laser energy, specimen base temperature, and detection rate is performed on the evaporation behavior of uranium dioxide (UO2). In laser-assisted mode, tip geometry and standing voltage also contribute to the evaporation behavior. In this investigation, it was determined that modifying the detection rate and temperature did not affect the evaporation behavior as significantly as laser energy. It was also determined that three laser evaporation regimes are present in UO2. Very low laser energy produces a behavior similar to DC-field evaporation, moderate laser energy produces the desired laser-assisted field evaporation characteristic and high laser energy induces thermal effects, negatively altering the evaporation behavior. The need for UO2 to be analyzed under moderate laser energies to produce accurate stoichiometry distinguishes it from other oxides. The following experimental conditions providing the best combination of mass resolving power, accurate stoichiometry, and uniform evaporation behavior: 50 K, 10 pJ laser energy, a detection rate of 0.003 atoms per pulse, and a 100 kHz repetition rate.

  19. Endoscopic diode laser therapy for chronic radiation proctitis.

    PubMed

    Polese, Lino; Marini, Lucia; Rizzato, Roberto; Picardi, Edgardo; Merigliano, Stefano

    2017-09-11

    The purpose of this study is to determine the effectiveness of endoscopic diode laser therapy in patients presenting rectal bleeding due to chronic radiation proctitis (CRP). A retrospective analysis of CRP patients who underwent diode laser therapy in a single institution between 2010 and 2016 was carried out. The patients were treated by non-contact fibers without sedation in an outpatient setting. Fourteen patients (median age 77, range 73-87 years) diagnosed with CRP who had undergone high-dose radiotherapy for prostatic cancer and who presented with rectal bleeding were included. Six required blood transfusions. Antiplatelet (three patients) and anticoagulant (two patients) therapy was not suspended during the treatments. The patients underwent a median of two sessions; overall, a mean of 1684 J of laser energy per session was used. Bleeding was resolved in 10/14 (71%) patients, and other two patients showed improvement (93%). Only one patient, who did not complete the treatment, required blood transfusions after laser therapy; no complications were noted during or after the procedures. Study findings demonstrated that endoscopic non-contact diode laser treatment is safe and effective in CRP patients, even in those receiving antiplatelet and/or anticoagulant therapy.

  20. Scaling Studies of Laser Proton Acceleration by Radiation Pressure Sail

    NASA Astrophysics Data System (ADS)

    Liu, T. C.; Dudinkova, G.; Liu, Chuan S.; Shao, X.; Sagdeev, R. Z.

    2010-02-01

    We present scaling studies of proton acceleration by short pulse, intense lasers in the region of radiation pressure acceleration of ultra thin foil. By defining the monoenergetic proton as having energy spread less than 10 percent in 2D PIC simulation, we studied the proton mono-energy profile as a function of the laser power and peak intensity, thin foil thickness and target density ratio to critical density. We found that the energy of monoenergetic proton scales linearly with the square root of laser power after fixing the target density ratio to critical density. The Rayleigh-Taylor (R-T) instability plays significant role in increasing the energy spread of accelerated protons. But, there are parameter regimes for instability remediation or suppression. Parameters of interest are for lasers in sub-Peta Watt range and producing quasi energetic protons to 250 Mev and carbon ion to 1 Gev. The simulation results are able to provide experimentalists with suggestion for optimal scaling for laser acceleration of thin foils for instability avoidance and optimal ion acceleration. Possible medical applications of the technology in proton cancer therapy is also discussed. )

  1. Guiding of Laser Beams in Plasmas by Radiation Cascade Compression

    SciTech Connect

    Kalmykov, Serguei; Shvets, Gennady

    2006-11-27

    The near-resonant heatwave excitation of an electron plasma wave (EPW) can be employed for generating trains of few-fs electromagnetic pulses in rarefied plasmas. The EPW produces a co-moving index grating that induces a laser phase modulation at the beat frequency. Consequently, the cascade of sidebands red- and blue-shifted from the fundamental by integer multiples of the beat frequency is generated in the laser spectrum. When the beat frequency is lower than the electron plasma frequency, the phase chirp enables laser beatnote compression by the group velocity dispersion [S. Kalmykov and G. Shvets, Phys. Rev. E 73, 046403 (2006)]. In the 3D cylindrical geometry, the frequency-downshifted EPW not only modulates the laser frequency, but also causes the pulse to self-focus [P. Gibbon, Phys. Fluids B 2, 2196 (1990)]. After self-focusing, the multi-frequency laser beam inevitably diverges. Remarkably, the longitudinal beatnote compression can compensate the intensity drop due to diffraction. A train of high-intensity radiation spikes with continually evolving longitudinal profile can be self-guided over several Rayleigh lengths in homogeneous plasmas. High amplitude of the EPW is maintained over the entire propagation length. Numerical experiments on the electron acceleration in the cascade-driven (cascade-guided) EPW [using the code WAKE by P. Mora and T. M. Antonsen Jr., Phys. Plasmas 4, 217 (1997)] show that achieving GeV electron energy is possible under realistic experimental parameters.

  2. Guiding of Laser Beams in Plasmas by Radiation Cascade Compression

    NASA Astrophysics Data System (ADS)

    Kalmykov, Serguei; Shvets, Gennady

    2006-11-01

    The near-resonant heatwave excitation of an electron plasma wave (EPW) can be employed for generating trains of few-fs electromagnetic pulses in rarefied plasmas. The EPW produces a co-moving index grating that induces a laser phase modulation at the beat frequency. Consequently, the cascade of sidebands red- and blue-shifted from the fundamental by integer multiples of the beat frequency is generated in the laser spectrum. When the beat frequency is lower than the electron plasma frequency, the phase chirp enables laser beatnote compression by the group velocity dispersion [S. Kalmykov and G. Shvets, Phys. Rev. E 73, 046403 (2006)]. In the 3D cylindrical geometry, the frequency-downshifted EPW not only modulates the laser frequency, but also causes the pulse to self-focus [P. Gibbon, Phys. Fluids B 2, 2196 (1990)]. After self-focusing, the multi-frequency laser beam inevitably diverges. Remarkably, the longitudinal beatnote compression can compensate the intensity drop due to diffraction. A train of high-intensity radiation spikes with continually evolving longitudinal profile can be self-guided over several Rayleigh lengths in homogeneous plasmas. High amplitude of the EPW is maintained over the entire propagation length. Numerical experiments on the electron acceleration in the cascade-driven (cascade-guided) EPW [using the code WAKE by P. Mora and T. M. Antonsen Jr., Phys. Plasmas 4, 217 (1997)] show that achieving GeV electron energy is possible under realistic experimental parameters.

  3. Counter-propagating radiative shock experiments on the Orion laser and the formation of radiative precursors

    NASA Astrophysics Data System (ADS)

    Clayson, T.; Suzuki-Vidal, F.; Lebedev, S. V.; Swadling, G. F.; Stehlé, C.; Burdiak, G. C.; Foster, J. M.; Skidmore, J.; Graham, P.; Gumbrell, E.; Patankar, S.; Spindloe, C.; Chaulagain, U.; Kozlová, M.; Larour, J.; Singh, R. L.; Rodriguez, R.; Gil, J. M.; Espinosa, G.; Velarde, P.; Danson, C.

    2017-06-01

    We present results from new experiments to study the dynamics of radiative shocks, reverse shocks and radiative precursors. Laser ablation of a solid piston by the Orion high-power laser at AWE Aldermaston UK was used to drive radiative shocks into a gas cell initially pressurised between 0.1 and 1.0 bar with different noble gases. Shocks propagated at 80 ± 10 km/s and experienced strong radiative cooling resulting in post-shock compressions of ×25 ± 2. A combination of X-ray backlighting, optical self-emission streak imaging and interferometry (multi-frame and streak imaging) were used to simultaneously study both the shock front and the radiative precursor. These experiments present a new configuration to produce counter-propagating radiative shocks, allowing for the study of reverse shocks and providing a unique platform for numerical validation. In addition, the radiative shocks were able to expand freely into a large gas volume without being confined by the walls of the gas cell. This allows for 3-D effects of the shocks to be studied which, in principle, could lead to a more direct comparison to astrophysical phenomena. By maintaining a constant mass density between different gas fills the shocks evolved with similar hydrodynamics but the radiative precursor was found to extend significantly further in higher atomic number gases (∼4 times further in xenon than neon). Finally, 1-D and 2-D radiative-hydrodynamic simulations are presented showing good agreement with the experimental data.

  4. LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Optimal two-mirror system for laser radiation focusing

    NASA Astrophysics Data System (ADS)

    Gitin, Andrey V.

    2009-10-01

    An optical system for laser radiation focusing, which consists of parabolic and elliptic mirrors, is considered. It is shown by the method of elementary reflections that the maximum concentration of laser radiation on the target can be achieved at a certain position of these mirrors.

  5. Bleaching effect of a 405-nm diode laser irradiation used with titanium dioxide and 3.5% hydrogen peroxide

    NASA Astrophysics Data System (ADS)

    Sakai, K.; Kato, J.; Nakazawa, T.; Hirai, Y.

    2007-09-01

    A 405-nm diode laser has recently been developed for soft tissue problems in dentistry. A new in-office bleaching agent consisting of a titanium dioxide photocatalyst and 3.5% hydrogen peroxide has proven to react well with light irradiated at a wavelength of around 400 nm. In this study, we evaluated the bleaching efficacy of a newly developed 405-nm diode laser on bovine teeth treated with a bleaching agent composed of titanium dioxide and 3.5% hydrogen peroxide. Sixteen bovine incisors were randomly divided into two groups: Group A, irradiated by the 405-nm diode laser at 200 mW; Group B, irradiated by the 405-nm diode laser at 400 mW. The bleaching agent with titanium dioxide and 3.5% hydrogen peroxide was applied to bovine enamel and irradiated for 1 min. The specimens were then washed and dried, and the same procedure was repeated nine more times. After irradiation, we assessed the effects of bleaching on the enamel by measuring the color of the specimens with a spectrophotometer and examining the enamel surfaces with a scanning electron microscope. L* rose to a high score, reaching a significantly higher post-treatment level in comparison to pretreatment. In a comparison of the color difference (Δ E) between Group A and Group B, the specimens in Group B showed significantly higher values after 10 min of irradiation for the post-treatment. No remarkable differences in the enamel surface morphology were found between the unbleached and bleached enamel. The use of a 405-nm diode laser in combination with a bleaching agent of titanium dioxide and 3.5% hydrogen peroxide may be an effective method for bleaching teeth without the risk of tooth damage.

  6. Effects of gamma irradiations on reactive pulsed laser deposited vanadium dioxide thin films

    NASA Astrophysics Data System (ADS)

    Madiba, I. G.; Émond, N.; Chaker, M.; Thema, F. T.; Tadadjeu, S. I.; Muller, U.; Zolliker, P.; Braun, A.; Kotsedi, L.; Maaza, M.

    2017-07-01

    Vanadium oxide films are considered suitable coatings for various applications such as thermal protective coating of small spacecrafts because of their thermochromic properties. While in outer space, such coating will be exposed to cosmic radiations which include γ-rays. To study the effect of these γ-rays on the coating properties, we have deposited vanadium dioxide (VO2) films on silicon substrates and subjected them to extensive γ-irradiations with typical doses encountered in space missions. The prevalent crystallographic phase after irradiation remains the monoclinic VO2 phase but the films preferential orientation shifts to lower angles due to the presence of disordered regions caused by radiations. Raman spectroscopy measurements also evidences that the VO2 structure is slightly affected by gamma irradiation. Indeed, increasing the gamma rays dose locally alters the crystalline and electronic structures of the films by modifying the V-V inter-dimer distance, which in turns favours the presence of the VO2 metallic phase. From the XPS measurements of V2p and O1s core level spectra, an oxidation of vanadium from V4+ towards V5+ is revealed. The data also reveal a hydroxylation upon irradiation which is corroborated by the vanishing of a low oxidation state peak near the Fermi energy in the valence band. Our observations suggest that gamma radiations induce the formation of Frenkel pairs. Moreover, THz transmission measurements show that the long range structure of VO2 remains intact after irradiation whilst the electrical measurements evidence that the coating resistivity decreases with gamma irradiation and that their transition temperature is slightly reduced for high gamma ray doses. Even though gamma rays are only one of the sources of radiations that are encountered in space environment, these results are very promising with regards to the potential of integration of such VO2 films as a protective coating for spacecrafts.

  7. Fractional ablative carbon dioxide laser resurfacing for skin rejuvenation and acne scars in Asians.

    PubMed

    Chan, Nicola P Y; Ho, Stephanie G Y; Yeung, Chi K; Shek, Samantha Y N; Chan, Henry H

    2010-11-01

    Ablative fractional resurfacing (AFR) is a new modality for photorejuvenation and acne scars which combines carbon dioxide (CO₂) laser ablation with fractional photothermolysis. The objective is to evaluate the efficacy and side effects of a new fractional CO₂ ablative device (Fraxel Re:pair) for skin rejuvenation and acne scars in Asians. Nine patients underwent one full-face treatment. The energy levels ranged from 30-70 mJ with coverage between 30% and 45%. Improvement in skin texture, laxity, wrinkles, enlarged pores, overall pigmentation irregularity, and adverse effects were assessed up to 6 months post-treatment. Standardized photographs using the Canfield Visia CR system® were assessed by two independent observers. Subjective improvement was assessed by patient questionnaires. Nine Chinese patients (skin types III and IV, mean age 44.8) were included. Statistically significant improvements were seen for skin texture, skin laxity, wrinkles, enlarged pores, and acne scars. The post-inflammatory hyperpigmentation rate was 55.5% and 11.1% at 1 and 6 months post-treatment, respectively. Eighty-six percent of patients were overall satisfied to very satisfied with the treatment. Ablative fractional CO₂ laser resurfacing was overall safe and effective for skin rejuvenation and acne scars in Asians. However, in view of the high post-inflammatory rate and the statistically significant but only mild to moderate improvement after a single treatment as observed in this study, there is a need to review the current role of fractional ablative CO₂ laser treatment as compared to fractional non-ablative for skin rejuvenation and acne scar treatment in Asians. © 2010 Wiley-Liss, Inc.

  8. 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.

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

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.

    2011-01-01

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

  10. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Selective metallisation of diamonds with the aid of laser radiation

    NASA Astrophysics Data System (ADS)

    Shafeev, Georgii A.; Pimenov, S. M.; Lubnin, Evgenii N.; Smolin, A. A.; Konov, Vitalii I.; Laptev, V. A.

    1995-02-01

    An experimental investigation was made of laser activation of diamond surfaces (single crystals and polycrystalline diamond films) prior to electroless before catalytic deposition of metals from solutions. The activation was carried out by a copper vapour laser or a KrF excimer laser in two ways: decomposition of a thin film of palladium acetylacetonate and local laser stimulated modification of the diamond surface by laser evaporation. An ohmic contact (Cu or Ni) with an adhesive strength of 3 N mm-2 was formed and the spatial resolution achieved was 10 μm.

  11. Experimental carbon dioxide laser brain lesions and intracranial dynamics. Part 2. Effect on brain water content and its response to acute therapy

    SciTech Connect

    Tiznado, E.G.; James, H.E.; Moore, S.

    1985-04-01

    Experimental brain lesions were created over the left parietooccipital cortex of the albino rabbit through the intact dura mater with high radiating carbon dioxide laser energy. The brain water content was studied 2, 6, and 24 hours after the insult. Another two groups of animals received acute therapy with either dexamethasone (1 mg/kg) or furosemide (1 mg/kg). In all groups, Evans blue extravasation uniformly extended from the impact crater into the surrounding white matter. The brain water content in the gray matter was elevated from the control value by 2 hours after impact and remained elevated at 6 and 24 hours. The white matter brain water content did not increase until 6 hours after impact and remained elevated in the 24-hour group. After dexamethasone treatment, there was a significant decrease of water in the gray matter, but not in the white matter. With furosemide therapy, there was no reduction of gray or white matter brain water.

  12. Er:YAG laser radiation applications in different medical branches

    NASA Astrophysics Data System (ADS)

    Jelínkova, Helena; Němec, Michal; Koranda, Petr; Šulc, Jan; Čech, Miroslav; Miyagi, Mitsunobu; Shi, Yi-Wei; Matsuura, Yuji

    2006-03-01

    For the purpose of biophotonics, free running and Q-switched Er:YAG lasers were constructed. As Q-switches the rotating mirror and Pockels cell were used. In the case of rotating mirror placed inside the resonator the maximum of generated laser energy was 210 mJ in a free-running mode regime when pulses up to 110 μs long (FWHM) were generated. The resulted parameters of the giant pulses were 30 mJ energy, and 250 ns pulse length. For the Pockels cell Q-switching, the laser was generating 325 mJ of energy in a 250 μs pulse, and 60 mJ of energy in a 60 ns pulse in the case of free running and Q-switched regime, respectively. This output properties together with the generating wavelength (2.94 μm), coinciding exactly with the absorption peak of water, giving us the possibility of using this radiation to the efficient interaction with biological tissue. The transport of the radiation to the interaction place was solved by the special cyclic olefin polymer coated silver hollow glass waveguides with the inner diameter of 700 μm and the length of 10 - 50 cm. For the contact treatment the sealed caps were used for preventing delivery system damage. The aim of this work was except of special laser systems development, the investigation ofthe effect differences between long (free running) and short (nanosecond) laser pulses on ophthalmic (cornea, sclera), urologic (ureter wall), or dental (enamel, dentine) tissue.

  13. Investigations of ion-irradiated uranium dioxide nuclear fuel with laser-assisted atom probe tomography

    NASA Astrophysics Data System (ADS)

    Valderrama, Billy

    Performance in commercial light water reactors is dictated by the ability of its fuel material, uranium dioxide (UO2), to transport heat generated during the fission process. It is widely known that the service lifetime is limited by irradiation-induced microstructural changes that degrade the thermal performance of UO2. Studying the role of complex, often interacting mechanisms that occur during the early stages of microstructural evolution presents a challenge. Phenomena of particular interest are the segregation of fission products to form bubbles and their resultant effect on grain boundary (GB) mobility, and the effect of irradiation on fuel stoichiometry. Each mechanism has a profound consequence on fuel thermal conductivity. Several advanced analytical techniques, such as transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, etc. have been used to study these mechanisms. However, they each have limitations and cannot individually provide the necessary information for deeper understanding. One technique that has been under utilized is atom probe tomography (APT), which has a unique ability to spatially resolve small-scale chemical variations. APT uses the principle of field ionization to evaporate surface ions for chemical analysis. For low electrical conductivity systems, a pulsed laser is used to thermally assist in the evaporation process. One factor complicating the analysis is that laser-material interactions are poorly understood for oxide materials and literature using this technique with UO2 is lacking. Therefore, an initial systematic study to identify the optimal conditions for the analysis of UO2 using laser-assisted APT was conducted. A comparative study on the evaporation behavior between CeO2 and UO2 was followed. CeO2 was chosen due to its technological relevancy and availability of comparative studies with laser-assisted APT. Dissimilar evaporation behavior between these materials was identified and attributed

  14. Optimized laser pulse profile for efficient radiation pressure acceleration of ions

    SciTech Connect

    Bulanov, S. S.; Schroeder, C. B.; Esarey, E.; Leemans, W. P.

    2012-12-21

    The radiation pressure acceleration regime of laser ion acceleration requires high intensity laser pulses to function efficiently. Moreover the foil should be opaque for incident radiation during the interaction to ensure maximum momentum transfer from the pulse to the foil, which requires proper matching of the target to the laser pulse. However, in the ultrarela-tivistic regime, this leads to large acceleration distances, over which the high laser intensity for a Gaussian laser pulse must be maintained. It is shown that proper tailoring of the laser pulse profile can significantly reduce the acceleration distance, leading to a compact laser ion accelerator, requiring less energy to operate.

  15. Optimized laser pulse profile for efficient radiation pressure acceleration of ions

    SciTech Connect

    Bulanov, S. S.; Schroeder, C. B.; Esarey, E.; Leemans, W. P.

    2012-09-15

    The radiation pressure acceleration regime of laser ion acceleration requires high intensity laser pulses to function efficiently. Moreover, the foil should be opaque for incident radiation during the interaction to ensure maximum momentum transfer from the pulse to the foil, which requires proper matching of the target to the laser pulse. However, in the ultrarelativistic regime, this leads to large acceleration distances, over which the high laser intensity for a Gaussian laser pulse must be maintained. It is shown that proper tailoring of the laser pulse profile can significantly reduce the acceleration distance, leading to a compact laser ion accelerator, requiring less energy to operate.

  16. 840-Hz Nd:YAG Laser Source of Sodium Resonance Radiation

    DTIC Science & Technology

    1992-05-11

    diode laser radiation to pump a Nd:YAG zig-zag slab laser system. Diode laser pumping reduces...distortion. In recent years the cost of diode laser arrays has fallen, and a diode - pumped , high repetition rate, high average power, high beam quality...Spatial far-field transverse profile of the 1.06-pm laser oscillator beam. 12 10 Spatial far-field transverse profile of the 1.32-pm laser oscillator

  17. A boron nitride CW Carbon dioxide waveguide laser for optically pumping heavy water

    NASA Astrophysics Data System (ADS)

    Evans, D. E.; Prunty, S. L.; Sexton, M. C.

    1980-01-01

    Boron nitride has been used to fabricate a 1 cm 3 CW CO 2 capillary waveguide laser which operates at 130 torr gas pressure, and generates 7 W of 10 μm radiation untuned and up to 3 W on individual grating-selected emission lines. Pressure broadened gain profiles are limited to ±200 MHz from line centre by longitudinal cavity mode spacing. Increased absorption of the 9μm band R(22) line by D 2O vapour is observed as this line is tuned across the broadened gain profile towards its D 2O absorption.

  18. Mathematical simulation of the amplification of 1790-nm laser radiation in a nuclear-excited He - Ar plasma containing nanoclusters of uranium compounds

    NASA Astrophysics Data System (ADS)

    Kosarev, V. A.; Kuznetsova, E. E.

    2014-02-01

    The possibility of applying dusty active media in nuclearpumped lasers has been considered. The amplification of 1790-nm radiation in a nuclear-excited dusty He - Ar plasma is studied by mathematical simulation. The influence of nanoclusters on the component composition of the medium and the kinetics of the processes occurring in it is analysed using a specially developed kinetic model, including 72 components and more than 400 reactions. An analysis of the results indicates that amplification can in principle be implemented in an active laser He - Ar medium containing 10-nm nanoclusters of metallic uranium and uranium dioxide.

  19. Generation and use of high power 213 nm and 266 nm laser radiation and tunable 210-400 nm laser radiation with BBO crystal matrix array

    DOEpatents

    Gruen, Dieter M.

    2000-01-01

    A 213 nm laser beam is capable of single photon ablative photodecomposition for the removal of a polymer or biological material substrate. Breaking the molecular bonds and displacing the molecules away from the substrate in a very short time period results in most of the laser photon energy being carried away by the displaced molecules, thus minimizing thermal damage to the substrate. The incident laser beam may be unfocussed and is preferably produced by quintupling the 1064 nm radiation from a Nd:YAG solid state laser, i.e., at 213 nm. In one application, the 213 nm laser beam is expanded in cross section and directed through a plurality of small beta barium borate (BBO) crystals for increasing the energy per photon of the laser radiation directed onto the substrate. The BBO crystals are arranged in a crystal matrix array to provide a large laser beam transmission area capable of accommodating high energy laser radiation without damaging the BBO crystals. The BBO crystal matrix array may also be used with 266 nm laser radiation for carrying out single or multi photon ablative photodecomposition. The BBO crystal matrix array may also be used in an optical parametric oscillator mode to generate high power tunable laser radiation in the range of 210-400 nm.

  20. INTERACTION OF LASER RADIATION WITH MATTER: Effect of the pulse duration on graphitisation of diamond during laser ablation

    NASA Astrophysics Data System (ADS)

    Kononenko, Vitalii V.; Kononenko, Taras V.; Pimenov, S. M.; Sinyavskii, M. N.; Konov, Vitalii I.; Dausinger, F.

    2005-03-01

    Processes of graphitisation of laser-irradiated polycrystalline diamond surface exposed to multipulse irradiation are studied experimentally. The thickness of the laser-modified layer as a function of the laser-pulse duration ranging from 100 fs to 1.5 μs and the effect of the radiation wavelength on this thickness are studied. It is shown that the diamond graphitisation during multipulse laser ablation is a thermally stimulated process. The dependences of the diamond-ablation rates on the radiation energy density under the action of laser pulses of various durations are presented.

  1. Comparative clinical trial of 2 carbon dioxide resurfacing lasers with varying pulse durations. 100 microseconds vs 1 millisecond.

    PubMed

    Duke, D; Khatri, K; Grevelink, J M; Anderson, R R

    1998-10-01

    To compare the clinical and histological effects of 2 carbon dioxide lasers with different pulse durations and to evaluate the effect of carbon dioxide laser pulse duration on postprocedure erythema, wound healing, and efficacy of wrinkle treatment. Prospective, randomized, comparative clinical trial. A university-affiliated hospital-based laser center. Thirty-five patients with facial wrinkles were enrolled in the study. Treatment sites included 15 perioral, 14 periorbital areas, and 6 full face. A 2-sided comparison was performed. One side of the study site was treated with the TruPulse laser (Tissue Technologies, Palomar Medical Products Inc, Lexington, Mass). The other side of the study site was treated with the UltraPulse 5000 laser (Coherent Medical Inc, Palo Alto, Calif). The 2 sides were treated to equivalent tissue effects rather than maintaining the number of passes. Photographs of the treatment areas at baseline, week 1, week 2, month 2, and month 6 were evaluated by a 5-member panel for degree of erythema, amount of edema, and percentage of wrinkle improvement. Silicon skin casts for profilometry measurements before and after the treatment were compared. To evaluate skin shrinkage, surface area before and after treatment of square tattoos on both cheeks of the full-face patients were computed using a digital imaging system. Histological sections before and after the procedure were analyzed. At week 1, 75% of the patients had more erythema on the UltraPulse than TruPulse sides. The difference in erythema (TruPulse less than UltraPulse) between the 2 treatment sides was clinically mild yet statistically significant for weeks 1 (P = .05) and 2 (P = .05). Although observed results favored the UltraPulse over the TruPulse, the difference in efficacy between the 2 lasers did not reach statistical significance. Compared with the longer pulse-duration carbon dioxide laser, the shorter pulse-duration carbon dioxide laser, used with higher energy and more passes

  2. CONTROL OF LASER RADIATION PARAMETERS: Generation of diffraction-limited nanosecond and subnanosecond pulses in a XeCl laser

    NASA Astrophysics Data System (ADS)

    Panchenko, Yu N.; Losev, V. F.; Dudarev, V. V.

    2008-04-01

    The generation of nanosecond and subnanosecond pulses in a XeCl laser is studied. The short radiation pulses are generated in a resonator with a SBS mirror. By focusing laser radiation inside and on the surface of a nonlinear medium, it is possible to generate pulses of duration 3 ns and 150 ps, respectively. The laser beams obtained in this way contain more than 70% of energy within the diffraction angle and have the signal-to-noise ration exceeding 104.

  3. Fractional Carbon Dioxide, Long Pulse Nd:YAG and Pulsed Dye Laser in the Management of Keloids.

    PubMed

    Annabathula, Ashwini; Sekar, C Shanmuga; Srinivas, C R

    2017-01-01

    Keloids are abnormal wound responses characterised by excessive deposition of collagen and glycoprotein. They are both aesthetically and symptomatically distressing for most of the patients. There are reports of keloid management with pulsed dye laser (PDL), fractional carbon dioxide (CO2) laser and neodymium-doped yttrium aluminium garnet (Nd:YAG) laser individually and also in combination of CO2 with PDL and CO2 with Nd:YAG. Here, we discuss a combination of all the 3 lasers as a therapy for keloids. This study aims to assess the efficacy of fractional CO2 laser, long pulse Nd:YAG laser and PDL in the management of keloids. Fifteen patients with keloids were treated by fractional CO2 laser, followed by PDL and long pulse Nd:YAG laser at monthly intervals. Four patients discontinued the study and were lost for follow-up. Photographs were taken at the beginning of the treatment and at the end of five sessions. Clinical improvement was analysed based on a visual analogue scale graded by three blinded observers after assessing the clinical photographs for the improvement in size, colour and aesthetic impression. Of the 11 patients, one patient had excellent improvement, one patient had good improvement, four patients had moderate improvement, two patients had mild improvement and three had no improvement. Lasers may have a synergistic effect when combined with other modalities of treatment but cannot be used as monotherapy in the treatment of keloids.

  4. NH{sub 3} laser as a radiation source for a two-frequency lidar

    SciTech Connect

    Vasil'ev, B I; Cho, Cheon W

    2000-12-31

    An NH{sub 3} laser pumped by a CO{sub 2} laser with spatial matching of output beams is investigated. Such a laser can be used as a radiation source for a two-frequency lidar operating in the range from 11 to 13.5 {mu}m. (laser applications and other topics in quantum electronics)

  5. Thermomechanical effect of pulse-periodic laser radiation on cartilaginous and eye tissues

    NASA Astrophysics Data System (ADS)

    Baum, O. I.; Zheltov, G. I.; Omelchenko, A. I.; Romanov, G. S.; Romanov, O. G.; Sobol, E. N.

    2013-08-01

    This paper is devoted to theoretical and experimental studies into the thermomechanical action of laser radiation on biological tissues. The thermal stresses and strains developing in biological tissues under the effect of pulse-periodic laser radiation are theoretically modeled for a wide range of laser pulse durations. The models constructed allow one to calculate the magnitude of pressures developing in cartilaginous and eye tissues exposed to laser radiation and predict the evolution of cavitation phenomena occurring therein. The calculation results agree well with experimental data on the growth of pressure and deformations, as well as the dynamics of formation of gas bubbles, in the laser-affected tissues. Experiments on the effect of laser radiation on the trabecular region of the eye in minipigs demonstrated that there existed optimal laser irradiation regimens causing a substantial increase in the hydraulic permeability of the radiation-exposed tissue, which can be used to develop a novel glaucoma treatment method.

  6. Interactive effects of atmospheric carbon dioxide and ultraviolet-B radiation on cotton growth and physiology

    NASA Astrophysics Data System (ADS)

    Reddy, K. Raja; Koti, S.; Zhao, Duli; Kakani, Vijaya Gopal; Gao, Wei

    2003-11-01

    Increasing surface UV-B radiation (UV-B) and atmospheric carbon dioxide concentration [(CO2)] are two major issues of climate change and agriculture. Although numerous studies have evaluated elevated UV-B or (CO2) effects on crop growth, development and yield, little is known about the interactive effects of these two factors on cotton. The objective of this study was to determine the combined effects of elevated (CO2) and UV-B radiation on cotton growth and physiology under controlled environmental conditions. The four treatments imposed were control [360 μmol (CO2) mol-1 and 8 kJ m-2 d-1 UV-B], +CO2 [720 μmol (CO2) mol-1 and 8 kJ m-2 d-1 UV-B], +UV-B [360 μmol (CO2) mol-1 and 16 kJ m-2 d-1 UV-B] and +CO2+UV-B [720 μmol (CO2) mol-1 and 16 kJ m-2 d-1 UV-B]. Treatments were imposed from emergence through three weeks after the first flower stage. Plants grown in +CO2 showed greater plant height, leaf thickness, leaf area, leaf and canopy photosynthesis (PN) and total biomass compared to the control, and fruit biomass was not affected by +CO2 conditions. On the other hand, plants grown in +UV-B treatment exhibited slower growth as reflected by reduced plant height, shorter internodes and branch lengths, and total biomass due to smaller leaf areas and less lower leaf PN. The +UV-B treatment also altered the leaf morphology and significantly reduced flower and petal lengths and petal area. Reduction in fruit production under both +UV-B and +CO2+UV-B treatments was due to reduced photosynthesis and alterations in reproductive development. The results also showed interactive effects of UV-B on cotton leaf PN, phenolics, wax content and some physiological parameters measured. Thus, a failure to increase cotton fruit production with +CO2 and +CO2+UV-B suggests that breeding UV-B radiation-tolerant cultivars is important in both the present and future solar UV-B radiation environments.

  7. The Ganymede Laser Altimeter - Instrument Design Overview with Radiation hard Transmitter

    NASA Astrophysics Data System (ADS)

    Althaus, C.; Hussmann, H.; Lingenauber, K.; Michaelis, H.; Kallenbach, R.; Oberst, J.

    2016-10-01

    The Ganymede Laser Altimeter (GALA) onboard of JUICE mission shall investigate Ganymede. A laser provides the measuring signal and has therefore to be robust and reliable in the environment of Jupiter, in particular with regard to radiation.

  8. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Spatial-temporal distribution of a mechanical load resulting from interaction of laser radiation with a barrier (analytic model)

    NASA Astrophysics Data System (ADS)

    Fedyushin, B. T.

    1992-01-01

    The concepts developed earlier are used to propose a simple analytic model describing the spatial-temporal distribution of a mechanical load (pressure, impulse) resulting from interaction of laser radiation with a planar barrier surrounded by air. The correctness of the model is supported by a comparison with experimental results.

  9. Laser Generated Anisotropic Drives for Radiation Transport Validation

    NASA Astrophysics Data System (ADS)

    Lanier, N. E.; Kline, J. K.; Hager, J. D.

    2013-10-01

    Many astrophysical phenomena are studied in the laboratory by developing a scaled platform whose energy drive is produced via a laser or pulsed power facility. The push to reach more energetic regimes often results in radiation drives that diverge from well-behaved Lambertian Planckian sources. In these cases, typical diffusive radiation flow models can break down. A new platform, that deliberately generates a well-characterized non-Planckian, anisotropic source, has been developed for the OMEGA laser. The resulting data will help validate more complex computational transport schemes like Sn or implicit Monte-Carlo (IMC) models. The platform contains a SiO2 foam mounted on a half-hohlraum. Anisotropy is achieved by inserting an obstruction of either a singular round aperture or annular ring between the foam and hohlraum. In addition, a thin beryllium layer delays the thermal component of the drive while the higher energy M-shell radiation propagates unhindered. The result is a highly non-Planckian, anisotropic, supersonic drive that eventually transitions to sub-sonic. Spectroscopic measurements constrain the source anisotropy, magnitude, and spectral content. Moreover, the Marshak position coupled with spectroscopic absorption measurements quantify the foam's internal energy.

  10. Collapsing Radiative Shocks in Argon Gas on the Omega Laser

    SciTech Connect

    Reighard, A B; Drake, R P; Dannenberg, K; Perry, T S; Robey, H A; Remington, B A; Wallace, R J; Ryutov, D D; Greenough, J; Knauer, J; Boehly, T; Bouquet, S; Calder, A; Rosner, R; Fryxell, B; Arnett, D; Koenig, M; Stone, J

    2003-11-01

    A number of astrophysical systems involve radiative shocks that collapse spatially in response to energy lost through radiation. Supernova remnants are an example of systems that cool enough to radiatively collapse. This is believed to produce thin, dense shells that are Vishniac unstable. This type of instability may be responsible for the convoluted structure of supernova remnants such as the Cygnus Loop. We are conducting experiments on the Omega laser intended to produce such collapsing shocks and to study their evolution. The experiments use the laser to accelerate a thin slab of driving material (beryllium) through 1.1 ATM of argon gas ({approx}2 mg/cc) at {approx}100 km/sec. The simulations also predict that the dense layer will be pushed ahead of the dense beryllium by the leading edge of the expansion of this material. The experiment is diagnosed in two ways. X-ray radiography has detected the presence of the dense shocked layer. These data indicate that the shock velocity is {approx}100 km/s. A unique, side-on application of the VISAR (Velocity Interferometer System for Any Reflector) technique is used to detect frequency shifts from ionization and any reflections from the edge of the dense shocked layer.

  11. CONTROL OF LASER RADIATION PARAMETERS: Cross modulation method of transformation of the spatial coherence of pulsed laser radiation in a nonlinear medium

    NASA Astrophysics Data System (ADS)

    Kitsak, M. A.; Kitsak, A. I.

    2008-04-01

    The cross modulation method of transformation of the spatial coherence of low-power pulsed laser radiation in a nonlinear medium is proposed. The method is realised experimentally in a multimode optical fibre. The estimates of the degree of spatial coherence of radiation subjected to the phase cross modulation demonstrated the high efficiency of this radiation decorrelation mechanism.

  12. Joint effects of elevated levels of ultraviolet-B radiation, carbon dioxide and ozone on plants.

    PubMed

    Krupa, Sagar V

    2003-12-01

    There is growing interest regarding the joint effects of elevated levels of surface ultraviolet B (UV-B) radiation, carbon dioxide (CO2) and ozone (O3) on plants. Our current knowledge of this subject is too limited to draw any specific conclusions, although one might state that such effects are likely to be highly species dependent and may be more than additive, additive or less than additive. There are a number of uncertainties associated with the experimental protocols used and the conclusions reached in many studies. Nevertheless, in North America, there appear to be genotypes of three monocot crop species (Avena sativa L., Oryza sativa L. and Sorghum vulgare L.); six dicot crops (Cucumis sativus L., Lactuca sativa L., Lycopersicon esculentum Mill., Phaseolus vulgaris L., Pisum sativum L. and Solanum tuberosum L.) and two conifer species (Pinus ponderosa Dougl. and Pinus taeda L.) that may be considered sensitive to the joint effects of elevated levels of UV-B, CO2 and O3. However, to provide a more reliable assessment or validation of the predictions, future research must consider the concept of plant response surfaces and describe them more fully in numerical terms. Achieving that objective will require close cooperation among a number of scientists representing geographic locations with known spatial and temporal differences in UV-B, CO2 and O3 to conduct experiments under their site-specific conditions, using common plant materials and experimental protocols.

  13. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Emission of charged particles from the surface of a moving target acted on by cw CO2 laser radiation

    NASA Astrophysics Data System (ADS)

    Kuznetsov, S. I.; Petrov, A. L.; Shadrin, A. N.

    1990-06-01

    An experimental investigation was made of the emission of charged particles due to the irradiation of moving steel and graphite targets with cw CO2 laser radiation. The characteristics of the emission current signals were determined for different laser irradiation regimes. The maximum emission current density from the surface of a melt pool ( ~ 1.1 × 10 - 2 A/cm2) and the average temperature of the liquid metal (~ 2040 K) were measured for an incident radiation power density of 550 W and for horizontal and vertical target velocities of respectively ~ 1.5 mm/s and ~ 0.17 mm/s. The authors propose to utilize this phenomenon for monitoring the laser processing of materials.

  14. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Mechanism of high-energy electron production in a laser plasma

    NASA Astrophysics Data System (ADS)

    Belyaev, V. S.

    2004-01-01

    A mechanism of high-energy electron production in the interaction of high-intensity short laser pulses with a solid target is proposed and analysed. The theoretical dependences of fast-electron kinetic energy on the parameters of laser radiation and target material are given. The effect of ionisation of the target material is considered. The generation of ultrastrong magnetic fields in the laser plasma is shown to play the key part in the formation, transfer, and acceleration of electron beams. This results in the production of vortex electric fields accelerating electrons. The theoretical dependences yield well-proved limits for the electron energy and are in good agreement with the results of experiments performed on high-intensity laser setups, including the results obtained with participation of the author.

  15. Xenon plasma sustained by pulse-periodic laser radiation

    SciTech Connect

    Rudoy, I. G.; Solovyov, N. G.; Soroka, A. M.; Shilov, A. O.; Yakimov, M. Yu.

    2015-10-15

    The possibility of sustaining a quasi-stationary pulse-periodic optical discharge (POD) in xenon at a pressure of p = 10–20 bar in a focused 1.07-μm Yb{sup 3+} laser beam with a pulse repetition rate of f{sub rep} ⩾ 2 kHz, pulse duration of τ ⩾ 200 μs, and power of P = 200–300 W has been demonstrated. In the plasma development phase, the POD pulse brightness is generally several times higher than the stationary brightness of a continuous optical discharge at the same laser power, which indicates a higher plasma temperature in the POD regime. Upon termination of the laser pulse, plasma recombines and is then reinitiated in the next pulse. The initial absorption of laser radiation in successive POD pulses is provided by 5p{sup 5}6s excited states of xenon atoms. This kind of discharge can be applied in plasma-based high-brightness broadband light sources.

  16. Influence of low-level laser radiation on kidney functions

    NASA Astrophysics Data System (ADS)

    Koultchavenia, Ekaterina V.

    1998-12-01

    Most of all renal diseases are accompanied by lowering of kidney functions. That makes the quality of the treatment worse. On an example 69 patients receiving Low-Level Laser Therapy (LLLT), the influence of the laser radiation on a contracting system of blood, on current of an active and inactive tubercular inflammation and on partial functions of kidneys were investigated. Is established, that LLLT does not render influence to a contracting system; promotes stopping of unspecific and moderate peaking of a specific inflammation of kidneys. Is proved, that after a rate of laserotherapy the improving of a blood micricirculation in kidney occurs in 57.9% of patients; a secretion - in 63.1% of the patients; a stimulation of urodynamic is fixed in 79% of cases. Magnification of diuresis, improving filtration and concentration functions of kidneys also is marked.

  17. Applications of laser-accelerated particle beams for radiation therapy

    NASA Astrophysics Data System (ADS)

    Ma, C.-M.; Fourkal, E.; Li, J. S.; Veltchev, I.; Luo, W.; Fan, J. J.; Lin, T.; Tafo, A.

    2011-05-01

    Proton beams are more advantageous than high-energy photons and electrons for radiation therapy because of their finite penetrating range and the Bragg peak near the end of their range, which have been utilized to achieve better dose conformity to the treatment target allowing for dose escalation and/or hypofractionation to increase local tumor control, reduce normal tissue complications and/or treatment time/cost. Proton therapy employing conventional particle acceleration techniques is expensive because of the large accelerators and treatment gantries that require excessive space and shielding. Compact proton acceleration systems are being sought to improve the cost-effectiveness for proton therapy. This paper reviews the physics principles of laser-proton acceleration and the development of prototype laserproton therapy systems as a solution for widespread applications of advanced proton therapy. The system design, the major components and the special delivery techniques for energy and intensity modulation are discussed in detail for laser-accelerated proton therapy.

  18. Silicon carbide detector for laser-generated plasma radiation

    NASA Astrophysics Data System (ADS)

    Bertuccio, Giuseppe; Puglisi, Donatella; Torrisi, Lorenzo; Lanzieri, Claudio

    2013-05-01

    We present the performance of a Silicon Carbide (SiC) detector in the acquisition of the radiation emitted by laser generated plasmas. The detector has been employed in time of flight (TOF) configuration within an experiment performed at the Prague Asterix Laser System (PALS). The detector is a 5 mm2 area 100 nm thick circular Nisbnd SiC Schottky junction on a high purity 4Hsbnd SiC epitaxial layer 115 μm thick. Current signals from the detector with amplitudes up to 1.6 A have been measured, achieving voltage signals over 80 V on a 50 Ω load resistance with excellent signal to noise ratios. Resolution of few nanoseconds has been experimentally demonstrated in TOF measurements. The detector has operated at 250 V DC bias under extreme operating conditions with no observable performance degradation.

  19. Laser Based Instruments Using Differential Absorption Detection for Above and Below Ground Monitoring of Carbon Dioxide

    NASA Astrophysics Data System (ADS)

    Humphries, S. D.; Barr, J. L.; Repasky, K. S.; Carlsten, J. L.; Spangler, L. H.; Dobeck, L. M.

    2008-12-01

    Carbon capture and sequestration in geologic formations provides a method to remove carbon dioxide (CO2) from entering the Earth's atmosphere. An important issue for the successful storage of CO2 is the ability to monitor geologic sequestration sites for leakage to verify site integrity. A field site for testing the performance of CO2 detection instruments and techniques has been developed by the Zero Emissions Research Technology (ZERT) group at Montana State University. A field experiment was conducted at the ZERT field site beginning July 9th, 2008 and ending August 7th, 2008 to test the performance of several CO2 detection instruments. The field site allows a controlled flow rate of CO2 to be released underground through a 100 m long horizontal pipe placed below the water table. A flow rate of 0.3 tons CO2/day was used for the entirety of this experiment. This paper describes the results from two laser based instruments that use differential absorption techniques to determine CO2 concentrations in real time both above and below the ground surface. Both instruments use a continuous wave (cw) temperature tunable distributed feedback (DFB) laser capable of tuning across several CO2 and water vapor absorption features between at 2003 nm and 2006 nm. The first instrument uses the DFB laser to measure path integrated atmospheric concentrations of CO2. The second instrument uses the temperature tunable DFB laser to monitor underground CO2 concentrations using a buried photonic bandgap optical fiber. The above ground instrument operated nearly continuously during the CO2 release experiment and an increase in atmospheric CO2 concentration above the release pipe of approximately 2.5 times higher than the background was observed. The underground instrument also operated continuously during the experiment and saw an increase in underground CO2 concentration of approximately 15 times higher than the background. These results from the 2008 ZERT field experiment demonstrate

  20. Ytterbium-doped Q-switched fiber laser based upon manganese dioxide (MnO2) saturable absorber.

    PubMed

    Hattori, Haroldo T; Khaleque, Abdul; Liu, Liming; Greck, Michael R

    2016-11-10

    Manganese dioxide (MnO2) is an abundant material that is widely used in many devices, such as alkaline batteries. At infrared frequencies, MnO2 is lossy and strongly absorbs light. These characteristics make MnO2 a potential candidate as a low-cost saturable absorber in Q-switched lasers. In this paper, we examine the performance of MnO2 as a saturable absorber in an ytterbium-doped Q-switched fiber laser: we show that it can produce pulses with durations ranging from 300 to 1800 ns.

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

    PubMed

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

    2016-04-01

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

  2. Experimental study on thermic effects, morphology and function of guinea pig cochlea: a comparison between the erbium:yttrium-aluminum-garnet laser and carbon dioxide laser.

    PubMed

    Ren, Dong-Dong; Chi, Fang-Lu

    2008-08-01

    Surgery of the inner ear requires atraumatic techniques to preserve the morphology of the inner ear. Recent experiment and clinical studies have demonstrated that several laser systems are suitable for cochleostomy. The goal of this study was to quantify the thermic effects, morphology and function of guinea pig cochlea in vivo by comparing the erbium:yttrium-aluminum-garnet (Er:YAG) laser and carbon dioxide (CO(2)) laser and to determine the optimum laser parameters for safe clinical treatment. A fenestration in the basal cochlear turn of guinea pigs was created. A type K thermocouple was placed on the membrane of round window to detect the local temperature change during laser irradiation. The auditory evoked brainstem response (ABR) was measured before and after laser application. Confocal laser microscopy and scanning electron microscopy (SEM) was used for cochlear morphology. An increased hearing loss immediately and 4 weeks later after irradiation was observed in animals with the higher power CO(2) laser in accordance with a higher temperature increase during laser application. In contrast, a wider safety scope of Er:YAG application in cochleostomy was presented with little temperature increase. These findings were correlated with the ultrastructural changes in guinea pig cochlea. The Er:YAG and CO(2) lasers are shown to be safe if the total amount of energy is kept within the limits applied in this study. In addition, on this preliminary basis by guinea pig laser cochleostomy, Er:YAG laser maybe less damaging to inner ear structures than CO(2) laser with a larger safety scope and less thermic effects. (c) 2008 Wiley-Liss, Inc.

  3. Frequency stabilization of distributed-feedback laser diodes at 1572 nm for lidar measurements of atmospheric carbon dioxide.

    PubMed

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

    2011-03-01

    We demonstrate a wavelength-locked laser source that rapidly steps through six wavelengths distributed across a 1572.335 nm carbon dioxide (CO(2)) absorption line to allow precise measurements of atmospheric CO(2) absorption. A distributed-feedback laser diode (DFB-LD) was frequency-locked to the CO(2) line center by using a frequency modulation technique, limiting its peak-to-peak frequency drift to 0.3 MHz at 0.8 s averaging time over 72 hours. Four online DFB-LDs were then offset locked to this laser using phase-locked loops, retaining virtually the same absolute frequency stability. These online and two offline DFB-LDs were subsequently amplitude switched and combined. This produced a precise wavelength-stepped laser pulse train, to be amplified for CO(2) measurements.

  4. Feasibility and Associated Limitations of Office-Based Laryngeal Surgery Using Carbon Dioxide Lasers.

    PubMed

    Hu, Hao-Chun; Lin, Shu-Yi; Hung, Yi-Ting; Chang, Shyue-Yih

    2017-05-01

    There are few reports evaluating awake, office-based carbon dioxide (CO2) laser surgery for laryngeal lesions. To date, this study was the largest reported case series of office-based laryngeal surgery by fiber delivery CO2 laser. Office-based laryngeal surgical procedures have become increasingly popular. Technical problems and treatment outcomes associated with the use of a CO2 laser for office-based laryngeal surgery have yet to be fully addressed. To discuss a single institution's clinical experience with office-based CO2 laser laryngeal surgery and the feasibility and limitations associated with this procedure. This retrospective study evaluated 49 laryngeal surgical procedures performed using a CO2 laser in 40 consecutive adult patients at a single institution in Taiwan from July 1, 2014, through September 30, 2015. Laryngeal lesions treated included vocal fold leukoplakia (n = 13), benign vocal fold lesions (n = 10), Reinke edema (n = 4), recurrent respiratory papillomatosis (n = 6), and lesions outside the vocal folds (n = 7). Office-based laryngeal surgery performed using a CO2 laser under topical anesthesia. Videolaryngoscopy was performed on all patients at each follow-up point. Among patients with benign vocal lesions and Reinke edema, videolaryngostroboscopy, voice laboratory measurements, perceptual measurements of vocal quality, and subjective evaluations were conducted before and after surgery. Among the 40 patients included in this study (28 men [70%] and 12 women [30%]; median [range] age, 56 [29-83] years), median follow-up time was 6.5 months (range, 1-21 months). Among the 49 procedures, 2 (4%) could not be tolerated by patients owing to severe gag reflex and laryngeal hypersensitivity, 6 (12%) could not completely evaporate lesions owing to an inadequate surgical field or laryngeal instability, and 1 (2%) led to a complication (ie, mild vocal fold wound stiffness). In addition, 2 patients with premalignant vocal fold

  5. Treatment of recurrent carcinoma at the base of the skull with carbon dioxide laser.

    PubMed

    Rontal, M; Rontal, E

    1983-10-01

    The extension of carcinoma to the cribriform plate is a poor prognostic finding. Two extremes of treatment approach have been advocated. On the one hand, patients may be abandoned to palliative chemotherapy. On the other hand, heroic and aggressive resections may be advocated including combined neurosurgical transdural and otolaryngologic facial-orbital resection. Armed with the surgical microscope and the CO2 laser there may be a place for a middle ground of therapy. We present our experience with recurrent tumor after full course radiation therapy and maxilloethmoidectomy. The biopsy proven recurrences were found at the cribriform plate but could not be shown to have crossed into the anterior cranial fossa by polytomography or high resolution CT scanning. The CO2 surgical laser delivered through the surgical microscope was used with repeated applications. Recurrent epidermoid carcinoma found to be confined to the nasal side of the cribriform plate can be controlled by careful microscopic stripping of soft tissue from the cribriform plate with a surgical laser.

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

    PubMed Central

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

    2017-01-01

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

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

    PubMed

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

    2017-01-01

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

  8. High Energy Ion Acceleration by Extreme Laser Radiation Pressure

    DTIC Science & Technology

    2017-03-14

    AFRL-AFOSR-UK-TR-2017-0015 High energy ion acceleration by extreme laser radiation pressure Paul McKenna UNIVERSITY OF STRATHCLYDE VIZ ROYAL COLLEGE...MM-YYYY)   14-03-2017 2. REPORT TYPE  Final 3. DATES COVERED (From - To)  01 May 2013 to 31 Dec 2016 4. TITLE AND SUBTITLE High energy ion acceleration...Prescribed by ANSI Std. Z39.18 Page 1 of 1FORM SF 298 3/15/2017https://livelink.ebs.afrl.af.mil/livelink/llisapi.dll 1 HIGH ENERGY ION ACCELERATION BY

  9. Investigation of temperature feedback signal parameters during neoplasms treatment by diode laser radiation

    NASA Astrophysics Data System (ADS)

    Belikov, Andrey V.; Gelfond, Mark L.; Shatilova, Ksenia V.; Semyashkina, Yulia V.

    2016-04-01

    Dynamics of temperature signal in operation area and laser power at nevus, papilloma, and keratoma in vivo removal by a 980+/-10 nm diode laser with "blackened" tip operating in continuous (CW) mode and with temperature feedback (APC) mode are presented. Feedback allows maintaining temperature in the area of laser treatment at a preset level by regulating power of diode laser radiation (automatic power control). Temperature in the area of laser treatment was controlled by measuring the amplitude of thermal radiation, which occurs when tissue is heated by laser radiation. Removal of neoplasm was carried out in CW mode with laser radiation average power of 12.5+/-0.5 W; mean temperature in the area of laser treatment was 900+/-10°C for nevus, 800+/-15°C for papilloma, and 850+/-20°C for keratoma. The same laser radiation maximal power (12.5 W) and targeted temperature (900°C) were set for nevus removal in APC mode. The results of investigation are real time oscillograms of the laser power and temperature in the area of laser treatment at neoplasms removal in two described above modes. Simultaneously with the measurement of laser power and the temperature in the area of laser treatment video recording of surgeon manipulations was carried out. We discuss the correlation between the power of the laser radiation, the temperature in the area of laser treatment and consistency of surgeon manipulation. It is shown that the method of removal (excision with or without traction, scanning) influences the temperature in the area of laser treatment. It was found, that at removal of nevus with temperature feedback (APC) mode to achieve comparable with CW mode temperature in the area of laser treatment (900+/-10°C) 20-50% less laser power is required. Consequently, removing these neoplasms in temperature feedback mode can be less traumatic than the removal in CW mode.

  10. Laser readable thermoluminescent radiation dosimeters and methods for producing thereof

    DOEpatents

    Braunlich, Peter F.; Tetzlaff, Wolfgang

    1989-01-01

    Thin layer thermoluminescent radiation dosimeters for use in laser readable dosimetry systems, and methods of fabricating such thin layer dosimeters. The thin layer thermoluminescent radiation dosimeters include a thin substrate made from glass or other inorganic materials capable of withstanding high temperatures and high heating rates. A thin layer of a thermoluminescent phoshphor material is heat bonded to the substrate using an inorganic binder such as glass. The dosimeters can be mounted in frames and cases for ease in handling. Methods of the invention include mixing a suitable phosphor composition and binder, both being in particulate or granular form. The mixture is then deposited onto a substrate such as by using mask printing techniques. The dosimeters are thereafter heated to fuse and bond the binder and phosphor to the substrate.

  11. Growing cartilage after IR laser radiation-ultrastructural study

    NASA Astrophysics Data System (ADS)

    Pelaez, A.; Vidal, Lourdes; Mendez, Luis I.; Parrado, C.; Perez de Vargas, I.

    1994-02-01

    The ultrastructural alterations of the chondrocytes in the growing cartilage after radiation by IR laser at a dose of 2 J/cm2 are described. Twenty albino Wistar rats have been used. The radiation was carried out on the left knee of the animals. Consequently, the animals were killed, and as soon as the pieces had been obtained they were subjected to the conventional techniques of fixation and inclusion for electron microscopy. Their ER is scarcely developed with disrupted and dilated cisternae noting few secretory vesicles in relation to the control animals. Likewise, degenerative phenomena in the mitochondria membranes and the endomembrane system were observed, in the shape of myelin. In the chondrocytes of the contralateral knee, few alterations were noted in relation to the controls.

  12. Laser readable thermoluminescent radiation dosimeters and methods for producing thereof

    DOEpatents

    Braunlich, P.F.; Tetzlaff, W.

    1989-04-25

    Thin layer thermoluminescent radiation dosimeters for use in laser readable dosimetry systems, and methods of fabricating such thin layer dosimeters are disclosed. The thin layer thermoluminescent radiation dosimeters include a thin substrate made from glass or other inorganic materials capable of withstanding high temperatures and high heating rates. A thin layer of a thermoluminescent phosphor material is heat bonded to the substrate using an inorganic binder such as glass. The dosimeters can be mounted in frames and cases for ease in handling. Methods of the invention include mixing a suitable phosphor composition and binder, both being in particulate or granular form. The mixture is then deposited onto a substrate such as by using mask printing techniques. The dosimeters are thereafter heated to fuse and bond the binder and phosphor to the substrate. 34 figs.

  13. Interaction of pulsed carbon dioxide laser beams with teeth in vitro.

    PubMed

    Brune, D

    1980-08-01

    Beams of pulsed carbon dioxide lasers with energy densities of about 10, 100 or 200 J/mm2 have been applied perpendicularly to third molars in vitro for the purpose of preparing cavities or pin holes for retention. A pulsed beam with an energy density of about 10 J/mm2 produced a hole approximately 2 mm deep with a diameter of about 0.2 mm. With a beam of 100 J/mm2 the hole produced penetrated the tooth to a depth of 4 mm. Minor cracks around the hole in both enamel and dentin could be observed. Around the position where the beam entered the enamel matrix a white mineralized layer was observed, while a brown discoloration was formed around the hole in the dentin at the beam exit. With an energy density of 200 J/mm2 the formation of cracks and discoloration was very pronounced. X-ray diffraction of lased tissue revealed an apatite structure. The wall in the lased hole exhibited a Vicker hardness number similar to that of enamel.

  14. INTERACTION OF LASER RADIATION WITH MATTER: Microstructures produced on spatially confined substrates exposed to repetitively pulsed laser radiation

    NASA Astrophysics Data System (ADS)

    Dolgaev, Sergei I.; Kirichenko, N. A.; Simakin, Aleksandr V.; Shafeev, Georgii A.

    2007-07-01

    The formation of microstructures is studied on metal substrates with characteristic dimensions of tens of micrometers that are comparable with the period of structures produced on extended substrates. Experiments were performed with nickel and nichrome targets composed of wires or a foil. Targets were irradiated in air by 510-nm, 20-ns pulses from a copper vapour laser operating at a pulse repetition rate of 7.5 kHz. Irradiation produced microcones and circular microstructures on substrates. The influence of the target geometry on the morphology and ordering of microstructures formed on it is demonstrated experimentally. The specific features of structures produced on spatially restricted targets are explained by the influence of boundary conditions on their development. A mathematical model of the initial phase of formation of the inhomogeneous profile of the surface of spatially restricted substrates exposed to laser radiation is proposed.

  15. CONTROL OF LASER RADIATION PARAMETERS: Harmonic modulation of radiation of an external-feedback semiconductor laser

    NASA Astrophysics Data System (ADS)

    Sukharev, Aleksandr G.; Napartovich, A. P.

    2007-02-01

    The appearance of the harmonic modulation regime at the Hopf bifurcation point is described analytically for a delayed-feedback semiconductor laser. The second-order delay differential equation with complex coefficients is derived. The frequency of oscillations appearing at the Hopf bifurcation point is determined by the solution of two relatively simple transcendental equations, from which the bifurcation point itself is found. These equations contain dependences on all the control parameters of the problem. The exact upper and lower limits of the oscillation frequency are found. A comparison with numerical results shows that the modulation frequency is preserved almost constant in a broad range of feedback phases. A procedure is proposed for determining the parameters of the laser providing the presence of bifurcations with a passage to oscillations with the specified frequency. The results obtained in the paper are of interest for WDM communication systems.

  16. Numerical Investigation of Radiative Heat Transfer in Laser Induced Air Plasmas

    NASA Technical Reports Server (NTRS)

    Liu, J.; Chen, Y. S.; Wang, T. S.; Turner, James E. (Technical Monitor)

    2001-01-01

    Radiative heat transfer is one of the most important phenomena in the laser induced plasmas. This study is intended to develop accurate and efficient methods for predicting laser radiation absorption and plasma radiative heat transfer, and investigate the plasma radiation effects in laser propelled vehicles. To model laser radiation absorption, a ray tracing method along with the Beer's law is adopted. To solve the radiative transfer equation in the air plasmas, the discrete transfer method (DTM) is selected and explained. The air plasma radiative properties are predicted by the LORAN code. To validate the present nonequilibrium radiation model, several benchmark problems are examined and the present results are found to match the available solutions. To investigate the effects of plasma radiation in laser propelled vehicles, the present radiation code is coupled into a plasma aerodynamics code and a selected problem is considered. Comparisons of results at different cases show that plasma radiation plays a role of cooling plasma and it lowers the plasma temperature by about 10%. This change in temperature also results in a reduction of the coupling coefficient by about 10-20%. The present study indicates that plasma radiation modeling is very important for accurate modeling of aerodynamics in a laser propelled vehicle.

  17. Dichromatic laser radiation effects on DNA of Escherichia coli and plasmids

    NASA Astrophysics Data System (ADS)

    Martins, W. A.; Polignano, G. A. C.; Guimarães, O. R.; Geller, M.; Paoli, F.; Fonseca, A. S.

    2015-04-01

    Dichromatic and consecutive laser radiations have attracted increased attention for clinical applications as offering new tools for the treatment of dysfunctional tissues in situations where monochromatic radiation is not effective. This work evaluated the survival, filamentation and morphology of Escherichia coli cells, and the induction of DNA lesions, in plasmid DNA exposed to low-intensity consecutive dichromatic laser radiation. Exponential and stationary wild type and formamidopyrimidine DNA glycosylase/MutM protein deficient E. coli cultures were exposed to consecutive low-intensity dichromatic laser radiation (infrared laser immediately after red laser) to study the survival, filamentation and morphology of bacterial cells. Plasmid DNA samples were exposed to dichromatic radiation to study DNA lesions by electrophoretic profile. Dichromatic laser radiation affects the survival, filamentation and morphology of E. coli cultures depending on the growth phase and the functional repair mechanism of oxidizing lesions in DNA, but does not induce single/double strands breaks or alkali-labile DNA lesions. Results show that low-intensity consecutive dichromatic laser radiation induces biological effects that differ from those induced by monochromatic laser radiation, suggesting that other therapeutic effects could be obtained using dichromatic radiation.

  18. Turbid Media Extinction Coefficient for Near-Infrared Laser Radiation

    NASA Astrophysics Data System (ADS)

    Dreischuh, T.; Gurdev, L.; Vankov, O.; Stoyanov, D.; Avramov, L.

    2015-03-01

    In this work, extended investigations are performed of the extinction coefficient of Intralipid-20% dilutions in distilled water depending on the Intralipid concentration, for laser radiation wavelengths in the red and near-infrared regions covering the so-called tissue optical window. The extinction is measured by using an approach we have developed recently based on the features of the spatial intensity distribution of laser-radiation beams propagating through semi-infinite turbid media. The measurements are conducted using separately two dilution- containing plexiglass boxes of different sizes and volumes, in order to prove the appropriateness of the assumption of semi-infinite turbid medium. The experimental results for the extinction are in agreement with our previous results and with empiric formulae found by other authors concerning the wavelength dependence of the scattering coefficient of Intralipid - 10% and Intralipid - 20%. They are also in agreement with known data of the water absorptance. It is estimated as well that the wavelengths around 1320 nm would be advantageous for deep harmless sensing and diagnostics of tissues.

  19. IV INTERNATIONAL CONFERENCE ON ATOM AND MOLECULAR PULSED LASERS (AMPL'99): Radiative and photochemical properties of organic compounds excited by high-power XeCl laser radiation

    NASA Astrophysics Data System (ADS)

    Kopylova, T. N.; Kuznetsova, Rimma T.; Svetlichnyi, Valerii A.; Sergeev, A. K.; Tel'minov, E. N.; Filinov, D. N.

    2000-06-01

    Radiative and photochemical properties of a number of laser dyes excited by focused radiation of a XeCl laser with intensity up to 200 MW cm-2 were studied. A method for measuring the gain of organic molecules under high-power excitation is proposed. The dependence of the dye transmittance for the pump radiation on its intensity was studied. It is shown that changes in energy, spectral, and time characteristics of radiation and the photostability of compounds under high-power excitation are associated with the formation of superluminescence.

  20. CONTROL OF LASER RADIATION PARAMETERS: Compensation for thermally induced aberrations in optical elements by means of additional heating by CO2 laser radiation

    NASA Astrophysics Data System (ADS)

    Soloviev, A. A.; Kozhevatov, I. E.; Palashov, O. V.; Khazanov, E. A.

    2006-10-01

    A method is proposed for compensating thermally induced phase distortions of laser radiation in absorbing optical elements. The method is based on supplementary heating of the peripheral region of the distorting element by the radiation from an auxiliary laser. A programme code has been developed for calculating the optimal parameters of supplementary radiation for minimising phase distortions. This code is based on the numerical solution of the thermal conductivity and static elasticity equations for a nonuniformly heated solid of cylindrical symmetry. Experiments reveal a high efficiency of the method for compensating distortions resulting from absorption of radiation with a Gaussian intensity profile.

  1. Correction method of bending loss in the hollow optical fiber for endoscopic submucosal dissection using carbon dioxide laser

    NASA Astrophysics Data System (ADS)

    Kusakari, Daisuke; Hazama, Hisanao; Awazu, Kunio

    2015-03-01

    Endoscopic submucosal dissection using carbon dioxide laser is a promising treatment of early digestive cancer because it can avoid the risk of perforation. Although a hollow optical fiber transmitting mid-infrared light has been used, it was observed that the irradiation effect was influenced by bending a gastrointestinal gastrointestinal endoscope due to the change in transmittance by the bending loss. Therefore, we quantitatively evaluated the change in the irradiation effect by bending the hollow optical fiber in the gastrointestinal endoscope and proposed a correction method to stabilize the irradiation effect. First, the relationship between the irradiated laser energy density and the incision depth for porcine stomach was measured by bending the head of the gastrointestinal endoscope. Next, the relationship between the bending angle of the head of the gastrointestinal endoscope and the temperature rise of the hollow optical fiber in the head of the gastrointestinal endoscope was measured during the laser irradiation. As a result, the laser energy density and the incision depth decreased as the bending angle increased, and linear correlation between the laser energy density and the incision depth was observed. It was found that the bending angle can be estimated by the ratio of the setting laser power to time derivative of the temporal profile of the temperature of the hollow optical fiber. In conclusion, it is suggested that the correction of the laser energy density and stabilization of the incision capability is possible by measuring the temporal profile of the temperature of the hollow optical fiber.

  2. Relieving pain in minor aphthous stomatitis by a single session of non-thermal carbon dioxide laser irradiation.

    PubMed

    Zand, Nasrin; Ataie-Fashtami, Leila; Djavid, Gholamreza Esmaeeli; Fateh, Mohsen; Alinaghizadeh, Mohammad-Reza; Fatemi, Seyyed-Mostafa; Arbabi-Kalati, Fateme

    2009-07-01

    This randomized controlled clinical trial was designed to evaluate the efficacy of single-session, non-thermal, carbon dioxide (CO(2)) laser irradiation in relieving the pain of minor recurrent aphthous stomatitis (miRAS) as a prototype of painful oral ulcers. Fifteen patients, each with two discrete aphthous ulcers, were included. One of the ulcers was randomly allocated to be treated with CO(2) laser (1 W of power in de-focused continuous mode) and the other one served as a placebo. Before laser irradiation, a layer of transparent, non-anesthetic gel was placed on both the laser lesions and the placebo lesions. The patients were requested to grade their pain on a visual analog scale up to 96 h post-operatively. The reduction in pain scores was significantly greater in the laser group than in the placebo group. The procedure itself was not painful, so anesthesia was not required. Powermetry revealed the CO(2) laser power to be 2-5 mW after passing through the gel, which caused no significant temperature rise or any visual effect of damage to the oral mucosa. Our results showed that a low-intensity, non-thermal, single-session of CO(2) laser irradiation reduced pain in miRAS immediately and dramatically, with no visible side effects.

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

    SciTech Connect

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

    1985-04-01

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

  4. Performance Evaluation of a New, Tunable-Diode Laser Trace-Gas Analyzer for Isotope Ratios of Carbon Dioxide

    NASA Astrophysics Data System (ADS)

    Sargent, S.

    2015-12-01

    Newly available interband cascade lasers (ICLs) have enabled the development of a family of tunable-diode laser trace-gas analyzers that do not require liquid nitrogen to cool the laser. The lasers are available in the 3000 to 6000 nm range, providing access to the strong mid-infrared absorption lines for important gases such as methane, nitrous oxide, and carbon dioxide. These ICLs are fabricated with distributed feedback to improve their stability and spectroscopic quality. A recently released trace-gas analyzer for carbon dioxide isotopes (TGA200A, Campbell Scientific, Inc.) was evaluated for short- and long-term precision using Allan variance. Accuracy and linearity of CO2 mole fraction was assessed with a set of seven NOAA standard reference gases ranging from 298.35 to 971.48 ppm. Dilution of high-concentration CO2 with CO2-free air demonstrated the linearity of isotope ratio measurements beyond 1000 ppm CO2. Two analyzer variants were tested: one for CO2, δ13C and δ18O; and the other for CO2 and δ13C at enhanced precision.

  5. Experimental study of the interaction of two laser-driven radiative shocks at the PALS laser

    NASA Astrophysics Data System (ADS)

    Singh, R. L.; Stehlé, C.; Suzuki-Vidal, F.; Kozlova, M.; Larour, J.; Chaulagain, U.; Clayson, T.; Rodriguez, R.; Gil, J. M.; Nejdl, J.; Krus, M.; Dostal, J.; Dudzak, R.; Barroso, P.; Acef, O.; Cotelo, M.; Velarde, P.

    2017-06-01

    Radiative shocks (RS) are complex phenomena which are ubiquitous in astrophysical environments. The study of such hypersonic shocks in the laboratory, under controlled conditions, is of primary interest to understand the physics at play and also to check the ability of numerical simulations to reproduce the experimental results. In this context, we conducted, at the Prague Asterix Laser System facility (PALS), the first experiments dedicated to the study of two counter-propagating radiative shocks propagating at non-equal speeds up to 25-50 km/s in noble gases at pressures ranging between 0.1 and 0.6 bar. These experiments highlighted the interaction between the two radiative precursors. This interaction is qualitatively but not quantitatively described by 1D simulations. Preliminary results obtained with XUV spectroscopy leading to the estimation of shock temperature and ion charge of the plasma are also presented.

  6. Absorption and scattering of laser radiation by the diffusion flame of aviation kerosene

    NASA Astrophysics Data System (ADS)

    Gvozdev, S. V.; Glova, A. F.; Dubrovskii, V. Yu; Durmanov, S. T.; Krasyukov, A. G.; Lysikov, A. Yu; Smirnov, G. V.; Solomakhin, V. B.

    2012-04-01

    The absorption coefficient of the radiation of a repetitively pulsed Nd : YAG laser with an average output power up to 6 W and of a cw ytterbium optical fibre laser with an output power up to 3 kW was measured in the diffusion flame of aviation kerosene burning on a free surface in the atmospheric air. The absorption coefficient as a function of flame length, radiation power, and radiation intensity, which was varied in the ~103 — 5×104 W cm-2 range, was obtained for two distances (1 and 2 cm) between the laser beam axis and the surface. The coefficient of radiation absorption by kerosene flame was compared with that in ethanol and kerosene — ethanol mixture flames. The radiation power scattered by a small segment of the kerosene flame irradiated by Nd : YAG laser radiation was measured as a function of longitudinal and azimuthal coordinates. An estimate was made of the total scattered radiation power.

  7. An open-path tunable diode laser absorption spectrometer for detection of carbon dioxide at the Bonanza Creek Long-Term Ecological Research Site near Fairbanks, Alaska

    NASA Astrophysics Data System (ADS)

    Bailey, D. Michelle; Adkins, Erin M.; Miller, J. Houston

    2017-09-01

    We have developed a low-power, open-path, near-infrared (NIR) tunable diode laser sensor for the measurement of near ground-level concentrations of greenhouse gases. Here, we report on instrument design, characterization, and initial measurements of carbon dioxide concentrations during deployment to a thermokarst collapse scar bog near Fairbanks, AK (USA). The optics "launch-box" portion of the instrument couples radiation from an NIR, distributed feedback diode laser operating near 1572 nm with a visible laser for alignment purposes. The outgoing beam is directed through a 3.2-mm hole in a parabolic mirror and the launch-box is oriented using a two axis, altitude-azimuth telescope mount such that the beam strikes a retroreflector target at a set distance downfield. The beam then retraces the path back to the launch-box where the light is collected on the surface of the parabolic mirror and focused onto a multimode fiber that transfers the radiation to an InGaAs detector. Sweeps over a 1.6 cm-1 spectral region were collected at a rate of 500 scans per second and were typically stored as 10 s sweep averages. These averaged sweeps could be individually spectrally fit for CO2 concentration or averaged into a single spectrum for fitting (after correction for slight frequency drift). Field data reported here was averaged for 2.5 min and was found to follow trends in diurnal cycles of CO2 concentration cycles reported by sensors located nearby in the field site.

  8. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Laser deposition of ZnO films on silicon and sapphire substrates

    NASA Astrophysics Data System (ADS)

    Zherikhin, A. N.; Khudobenko, A. I.; Williams, R. T.; Wilkinson, J.; User, K. B.; Xiong, Gang; Voronov, Valerii V.

    2003-11-01

    Laser deposition of zinc oxide films is studied. An intermediate screen is used to prevent microparticles formed during laser ablation of the target from falling on the film. The effect of deposition conditions on the morphology of the film, its electrical properties and crystal structure is studied. It is shown that the laser deposition technique can be used to obtain films of both types. The resistivity of the films was 0.07 Ω cm for films with the n-type conduction and 0.08 Ω cm for films with the p-type conduction. The photoluminescence studies of the films have shown that stimulated radiation is generated in the films under pump intensity exceeding 6 MW cm-2.

  9. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Coherent phase control of excitation of atoms by bichromatic laser radiation in an electric field

    NASA Astrophysics Data System (ADS)

    Astapenko, Valerii A.

    2005-06-01

    A new method for coherent phase control of excitation of atoms in a discrete spectrum under the action of bichromatic laser radiation with the frequency ratio 1:2 is analysed. An important feature of this control method is the presence of a electrostatic field, which removes the parity selection rule for one of the control channels. It is shown that for the phase difference between the monochromatic radiation components, corresponding to the destructive interference between channels, there exists the electrostatic field strength at which the excited atomic transition is 'bleached'. It is proposed to use luminescence at the adjacent atomic transition for detecting the phase dependence of optical excitation.

  10. EUV and debris characteristics of a laser-plasma tin dioxide nano-particle colloidal jet target

    NASA Astrophysics Data System (ADS)

    Kaku, Masanori; Suetake, Sumihiro; Senba, Yusuke; Katto, Masahito; Kubodera, Shoichi

    2008-03-01

    Debris characteristics and its reduction have been investigated for a laser-produced plasma (LPP) extreme ultraviolet (EUV) source using a colloidal jet target containing tin dioxide nano-particles. Dominant deposited debris on a witness plate was found to have a form of oxidized tin (SnO x) originated from nano-particles. Quantitative debris amounts were determined by total laser energy irradiated onto a target, not by laser irradiation modes, such as single or double pulse irradiation. In-situ low-temperature (100°C) heating of a plate was effective to reduce the deposited debris amount, since colloidal debris was easily vaporized by the heat. Another approach to remove the deposited debris was roomtemperature photon processing using incoherent vacuum ultraviolet (VUV) emission at 126 nm. X-ray photoelectron spectroscopy (XPS) analysis has shown that the deposited SnOx debris layer was deoxidized by the 126 nm VUV photon energy.

  11. Effect of high-power laser radiation on characteristics of thin silicon nitride films

    SciTech Connect

    Roizin, Y.O.; Khuan, K.S.

    1986-09-01

    High-power laser radiation is used in microelectronic technology for purposes such as annealing radiation defects in MOS structures after ion implantation. This paper considers accumulated changes in electrical characteristics of metal-nitride-oxide-semiconductor (MNOS) structures under the action of neodymium laser pulses with an energy density below the visible damage threshold. The experimental results obtained are interpreted.

  12. Mode structure in the far field radiation of a leaky-wave multiple quantum well laser

    SciTech Connect

    Nekorkin, S M; Zvonkov, B N; Karzanova, Maria V; Dikareva, Natalia V; Aleshkin, V Ya; Dubinov, A A

    2012-10-31

    The radiation patterns of a leaky-wave InGaAs/GaAs/InGaP laser are studied. In the subthreshold regime, several peaks are found, corresponding to the emission of fundamental and excited modes. The dependences of the amplitude, position and width of the peaks on the pump current are investigated and explained. (measurement of laser radiation parameters)

  13. Terahertz radiation generation by nonlinear mixing of two laser beams over a thin foil

    SciTech Connect

    Chauhan, Santosh; Parashar, J.

    2015-07-31

    Terahertz radiation generation via nonlinear mixing of two laser beams incident over a thin metal foil is explored. The lasers exert a ponderomotive force on the electrons of metal foil at beat frequency which lies in the terahertz range. The metal foil acts as antenna, producing terahertz radiations, highly directional in nature.

  14. Phosphopeptide screening using nanocrystalline titanium dioxide films as affinity matrix-assisted laser desorption ionization targets in mass spectrometry.

    PubMed

    Niklew, Marie-Luise; Hochkirch, Ulrike; Melikyan, Anna; Moritz, Thomas; Kurzawski, Sandra; Schlüter, Hartmut; Ebner, Ingo; Linscheid, Michael W

    2010-02-01

    The use of nanocrystalline titanium dioxide films as affinity targets for the selective isolation and enrichment of phosphopeptides with subsequent analysis by matrix-assisted laser desorption ionization (MALDI) mass spectrometry is described. A strong affinity of phosphopeptides to anatase titanium dioxide surfaces is observed, and a standard protocol for the selective isolation and enrichment of phosphopeptides on titanium dioxide films using a proteolytic digest of alpha- and beta-casein was developed. All washing and elution procedures using these films can be processed directly on the MALDI target, thereby avoiding sample contamination and losses. In addition, the enrichment of the phosphopeptides was improved due to a considerable enlargement of the surface. Several film substrates compatible with routine inlet systems of mass spectrometers, as conductive glass, aluminum, and silicon, have been manufactured and tested. A biological application was examined by the human fibrinogen-thrombin system. For a quantification and comparison of different expression levels of phosphoproteins in biological systems, the peptides were labeled with S-methyl thioimidate reagents. The capability of this method for high-throughput applications make the use of mesoporous titanium dioxide films as an affinity MALDI target a promising tool in phosphoproteomics. A combination of an amidation protocol showed that a quantification of phosphorylated peptides can easily be performed using TiO(2) films.

  15. Effect of reactor radiation on the operation of a neodymium inorganic liquid laser

    SciTech Connect

    Dobrovol'skii, A F; Kabakov, D V; Seregin, A A; Seregina, E A; Tikhonov, G V

    2009-02-28

    The radiation parameters of a neodymium liquid laser based on phosphorus oxychloride are measured upon irradiation of the laser medium by neutrons and gamma-rays from a BARS-6 two-zone reactor. This irradiation increases the laser energy by 20%-30% compared to the laser energy in the absence of irradiation. The lasing threshold is observed to decrease with increasing the irradiation dose. In the case of simultaneous optical and nuclear pumping of the laser medium, the free-running regime of laser operation converts to the regime of high-power pulses. (lasers)

  16. Experience of laser radiation for treatment of oral mucous lesions of different etiologies

    NASA Astrophysics Data System (ADS)

    Mosesyants, Elvira N.; Zazulevskaya, Lidiya Y.; Shevtsova, Elena

    1997-05-01

    Laser irradiation use for treatment of different manifestations of oral mucous diseases during the last 10 years. The aim of this research was study of the results of use He-Ne laser radiation in combination with main therapy for treatment of oral mucous lesions of different aetiology. He-Ne laser irradiation use for radiation of lesions were caused by different aetiology reasons. Under the observation was 116 patients 20 - 64 years old, who had and hadn't background pathology. There were biochemical, immunological controls. Data of research confirmed positive effect of use He-Ne laser radiation.

  17. 3D photomechanical model of tooth enamel ablation by Er-laser radiation

    NASA Astrophysics Data System (ADS)

    Belikov, Andrey V.; Shatilova, Ksenia V.; Skrypnik, Alexei V.

    2014-02-01

    The three-dimensional (3D) photomechanical model of human tooth enamel ablation is described. It takes into account: the structural peculiarities of enamel, Er-laser beam energy spatial distribution and laser radiation attenuation in the tissue. Dynamics change of enamel coefficient of absorption during ablation is also discussed. We consider the 3D photomechanical model of incomplete removal (modification) of the enamel rods by the pressure of water contained in the enamel pores and heated by laser radiation, and complete removal (ablation) of the enamel rods as result of hydroxyapatite heated by laser radiation and evaporation. Modeling results are in close agreement with the experimental results.

  18. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Effect of compression of a laser plasma on the generation of harmonics and hard x radiation

    NASA Astrophysics Data System (ADS)

    Apollonov, V. V.; Derzhavin, S. I.; Kazakov, K. Kh

    1993-02-01

    A compression of a plasma produced at a conical target by a low-intensity beam (q≲10 GW/cm2) from a CO2 laser has been studied. The effect of this compression on the onset of the parametric instability responsible for the generation of harmonics and of hard x radiation has also been studied. A qualitative interpretation of the results is offered.

  19. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Collective migration of adsorbed atoms on a solid surface in the laser radiation field

    NASA Astrophysics Data System (ADS)

    Andreev, V. V.; Ignat'ev, D. V.; Telegin, Gennadii G.

    2004-02-01

    The lateral (in the substrate plane) interaction between dipoles induced in particles adsorbed on a solid surface is studied in a comparatively weak laser radiation field with a Gaussian transverse distribution. It is shown that the particles migrate over the surface in the radial direction either outside an illuminated spot with the formation of a 'crater' or inside the spot with the formation of a 'mound'.

  20. Temporal structure of X-ray radiation pulses of picosecond laser plasma

    SciTech Connect

    Belyaev, V S; Kovkov, D V; Matafonov, A P; Karabadzhak, G F; Raikunov, G G; Faenov, A Ya; Pikuz, S A; Skobelev, I Yu; Pikuz, T A; Fokin, D A; Fortov, V E; Ignat'ev, G N; Kapitanov, S V; Krapiva, P S; Korotkov, K E

    2013-09-30

    The shape of the X-ray pulse generated by picosecond laser plasma is experimentally studied. The unusual phenomenon was experimentally observed for the first time for targets made of moderate-heavy chemical elements, namely, the pulse of hard X-ray radiation generated by laser plasma at the laser radiation flux of ∼10{sup 18} W cm{sup -2} had a longer duration than the pulse of softer X-ray radiation. A simple kinetic model is suggested for explaining this fact. We have suggested a method for controlling the temporal shape of X-ray pulse emitted by laser plasma by varying the contrast of laser pulse. (interaction of laser radiation with matter)

  1. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Study of symmetrising action of laser prepulse on inhomogeneity of thin foil heating

    NASA Astrophysics Data System (ADS)

    Ilyasov, A. O.; Lebo, I. G.; Mikhailov, Yu A.; Rozanov, Vladislav B.; Sklizkov, G. V.; Starodub, Aleksandr N.; Tishkin, V. F.

    2005-07-01

    The results of theoretical and experimental studies of plasma heating by laser radiation having an inhomogeneous spatial structure are presented as well as the results of investigation of the symmetrising action of a laser prepulse on the inhomogeneity of heating of thin foils modelling thin-walled laser thermonuclear synthesis targets. The high efficiency of the method of ablation pressure symmetrisation by a laser prepulse is demonstrated.

  2. Resonance laser-induced ionisation of sodium vapour taking radiative transfer into account

    SciTech Connect

    Kosarev, N I; Shaparev, N Ya

    2006-04-30

    The problem of ionisation of atomic sodium in the field of resonance laser radiation is numerically solved taking radiative transfer into account. Seed electrons are produced due to the mechanism of associative ionisation, then they gain energy in superelastic processes (collisions of the second kind) and initiate the avalanche ionisation of the medium by electron impact. We studied the effect of secondary radiation on the laser pulse propagation upon competition between the ionising and quenching electron collisions with excited atoms, on the kinetics of ionisation-induced vapour bleaching, and the plasma channel expansion in the form of a halo. (interaction of laser radiation with matter)

  3. An application of laser technology in developing the closed ionizing radiation sources

    SciTech Connect

    Kim, G.N.; Bigeliene, T.A.; Rakhmonov, A.A.

    1993-12-31

    This paper presents the results of studying the possibilities to apply laser technology for developing radionuclide sources, in particular, closed radionuclide ionizing radiation sources. The most unique properties of laseres are their ability to create a high and superhigh radiation energy concentration to be sufficient for melting and evaporating any known material, the possibility to focus the radiation on small and very small surface areas with a small angle of convergence, as well as the strict direction of the laser radiation and it`s possibility to penetrate into closed volumes through transparent walls.

  4. Simulation of planetary entry radiative heating with a CO2 gasdynamic laser

    NASA Technical Reports Server (NTRS)

    Lundell, J. H.; Dickey, R. R.; Howe, J. T.

    1975-01-01

    Heating encountered during entry into the atmospheres of Jupiter, Saturn, and Uranus is described, followed by a discussion of the use of a CO2 gasdynamic laser to simulate the radiative component of the heating. Operation and performance of the laser is briefly described. Finally, results of laser tests of some candidate heat-shield materials are presented.

  5. Simulation of planetary entry radiative heating with a CO2 gasdynamic laser

    NASA Technical Reports Server (NTRS)

    Lundell, J. H.; Dickey, R. R.; Howe, J. T.

    1975-01-01

    Heating encountered during entry into the atmospheres of Jupiter, Saturn, and Uranus is described, followed by a discussion of the use of a CO2 gasdynamic laser to simulate the radiative component of the heating. Operation and performance of the laser is briefly described. Finally, results of laser tests of some candidate heat-shield materials are presented.

  6. Pump radiation distribution in multi-element first cladding laser fibres

    SciTech Connect

    Mel'kumov, Mikhail A; Bufetov, Igor' A; Bubnov, M M; Shubin, Aleksei V; Semenov, S L; Dianov, Evgenii M

    2005-11-30

    Pump radiation transfer is studied experimentally in multi-element first cladding laser fibres. A model of this process is proposed, which is in good agreement with experimental results. An all-fibre single-mode cw ytterbium laser based on a three-element first cladding fibre with an output power of 100W is fabricated. (lasers)

  7. Photosensitivity of a diamond detector to laser radiation in the 220 - 355-nm region

    SciTech Connect

    Lipatov, E I; Panchenko, Aleksei N; Tarasenko, Viktor F; Shein, J; Krishnan, M

    2001-12-31

    The photosensitivity of detectors of laser radiation based on the natural type IIa diamond (Alameda Applied Sciences Corporation, USA) are studied at the wavelengths 222, 308, 337, and 353 nm. The limiting intensities (0.5 - 4 MW cm{sup -2}) of UV laser radiation are determined at which the detectors operate in a linear regime. (laser applications and other topics in quantum electronics)

  8. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Effects of laser radiation on immobile and fast-moving targets

    NASA Astrophysics Data System (ADS)

    Osipov, V. V.; Lisenkov, V. V.; Shitov, V. A.; Luk'yashin, K. E.

    2009-04-01

    We have studied the effects of laser pulses up to 50 J in energy and up to 1100 μs in duration, with a rise time of ~300 μs, on immobile and moving (linear velocity of up to 104 cm s-1) stainless steel targets. The results indicate that, in the vapour above an immobile target, optical breakdown develops at a spot-averaged power density of 5.5×106 W cm-2, against 7.3×106 W cm-2 in air. This undesirable effect can be eliminated even at an order of magnitude higher incident power density by rapidly rotating the target (linear velocity of ~50 cm s-1 relative to the laser beam). At incident power densities in the range (0.6-1.2)×107 W cm-2 (incident powers from 12 to 24 kW), evaporation from a rotating target is intermittent. To interpret this effect, a numerical model is developed which takes into account the influence of target burning. Its predictions agree with the evaporation behaviour observed in our experiments. The thicknesses of the evaporated and molten layers are evaluated as functions of laser beam parameters and target velocity, with reference to the optimisation of laser surface processing conditions.

  9. Infrared heterodyne spectrometer measurements of vertical profile of tropospheric ammonia and ozone. [using dual carbon dioxide laser

    NASA Technical Reports Server (NTRS)

    Peyton, B. J.; Lange, R. A.; Savage, M. G.; Seals, R. K.; Allario, F.

    1977-01-01

    Remote sensing of the concentration and vertical distribution of atmospheric gases has been carried out using a dual CO2 laser multichannel infrared heterodyne spectrometer (IHS). The high specificity and nearly quantum-noise-limited sensitivity of the IHS provide the capability of scanning individual signature lines of selected atmospheric constituents in the 9 to 11 micron region. A comprehensive investigation of the spectral overlap between CO2 laser local oscillator transitions and selected atmospheric constituents was performed; measurements of the atmospheric absorption of solar radiation from the ground were carried out at selected laser transitions for ammonia and ozone.

  10. A spherical hohlraum design with tetrahedral 4 laser entrance holes and high radiation performance

    NASA Astrophysics Data System (ADS)

    Jiang, Shaoen; Jing, Longfei; Huang, Yunbao; Li, Haiyan; Huang, Tianxuan; Ding, Yongkun

    2016-12-01

    As usual cylindrical hohlraum with double laser ring cones may lead to serious laser-plasma interaction, such as the simulated Raman scatter and cross-beam energy transfer effect, spherical hohlraum with octahedral 6 Laser Entrance Holes (LEHs) and single cone laser beams, was investigated and reported to have a consistent high radiation symmetry during the whole implosion process. However, it has several potential challenges such as the smaller space left for diagnosis and the assembly of centrally located capsule. In this paper, based on the view-factor model, we investigate the radiation symmetry and the drive temperature on the capsule located in the spherical hohlraum with tetrahedral 4 LEHs and single cone laser beams, since there is more available space for laser disposition and diagnosis. Then, such target is optimized on the laser beam pointing direction to achieve a high radiation performance, i.e., the radiation symmetry and drive temperature on the capsule. Finally, an optimal spherical hohlraum with optimal laser beam pointing has been demonstrated and compared with the spherical hohlraum with octahedral 6 LEHs. The resulting radiation symmetry and the drive temperature shows that it has almost a similar radiation symmetry (the radiation asymmetry variation is no more than 0.2%), and higher drive temperature (the temperature has been increased by 1.73%, and an additional 133 kJ energy of 2 MJ energy for fusion can be saved).

  11. Successful Treatment of Keloid With Fractionated Carbon Dioxide (CO2) Laser and Laser-Assisted Drug Delivery of Triamcinolone Acetonide Ointment in an African-American Man.

    PubMed

    Kraeva, Ekaterina; Ho, Derek; Jagdeo, Jared

    2017-09-01

    Keloids are fibrous growths that occur as a result of abnormal response to dermal injury. Keloids are cosmetically disfiguring and may impair function, often resulting in decreased patient quality-of-life. Treatment of keloids remains challenging, and rate of recurrence is high. We present a case of a 39-year-old African-American man (Fitzpatrick VI) with a 10-year history of keloid, who was successfully treated with eight sessions of fractionated carbon dioxide (CO2) laser immediately followed by laser-assisted drug delivery (LADD) of topical triamcinolone acetonide (TAC) ointment and review the medical literature on fractionated CO2 laser treatment of keloids. To the best of our knowledge, this is the first report of successful treatment of a keloid using combination therapy of fractionated CO2 laser and LADD with topical TAC ointment in an African-American man (Fitzpatrick VI) with excellent cosmetic results sustained at 22 months post-treatment. We believe that this combination treatment modality may be safe and efficacious for keloids in skin of color (Fitzpatrick IV-VI) and other patients. This case highlights the ability of laser surgeons to safely use fractionated CO2 lasers in patients of all skin colors.

    J Drugs Dermatol. 2017;16(9):925-927.

    .

  12. Heating of blood by low-intensity laser radiation

    NASA Astrophysics Data System (ADS)

    Korolevich, Alexander N.; Astafyeva, Liudmila G.; Dubina, Natali S.; Vecherinski, Sergei I.; Belsley, Michael S.

    2003-10-01

    Theoretical and experimental studies of the influence of low-intensity laser radiation, on the velocity of microcirculation of the erythrocytes of patients with the cardiovascular disease "in vivo" are carried out. Dynamic light scattering techniques were used to monitor the variation in the perfusion of micro capillary blood flow during irradiation under "in vivo" conditions and compared to the change in average size of aggregates of the blood effects observed "in vitro" using static scattering of light. It is shown that the process of the fragmentation of erythrocytes depends on amount of energy absorbed by biological tissues. This conclusion is supported by the good qualitative agreement with the theoretical model, based on the heat transfer theory within the dermis.

  13. Mobility of Electron in DNA Crystals by Laser Radiation

    NASA Technical Reports Server (NTRS)

    Zhang, Kaixi; Zhao, Qingxun; Cui, Zhiyun; Zhang, Ping; Dong, Lifang

    1996-01-01

    The mobility of electrons in laser radiated DNA is closed to the energy transfer and energy migration of a biological molecule. Arrhenius has studied the conductivity of the electrons in a biological molecule. But his result is far from the experimental result and meanwhile the relation between some parameters in his theory and the micro-quantities in DNA is not very clear. In this paper, we propose a new phonon model of electron mobility in DNA and use Lippman-Schwinger equation and S-matrix theory to study the mobility of electrons in DNA crystal. The result is relatively close to the experiment result and some parameters in Arrhenius theory are explained in our work.

  14. Laser radiation of blood in treating patients with postinfarction heart

    NASA Astrophysics Data System (ADS)

    Tashchuk, V.; Polyanskaya, O.; Chaplinsky, R.; Ilashchuk, I.; Kulyk, T.

    1999-11-01

    168 patients on the postclinical stage of treatment of acute myocardial infarction were examined by means of the use of basic antiischemic therapy and intravenous laser radiation of blood (LRB). All patients were studied with the help of transesophageal electrocardiostimulation, bicycle ergometry, echocardiography and Holter ECG monitoring in the dynamics of prolonged observation and treatment. The analysis of efficiency of the LRB has shown that the most minimal degree of myocardial ischemization was marked in patients after intravenous LRB. The patients before LRB had the greater reduction of coronary reserve. The use of LRB has given the possibility to the optimization of therapy in patients on the stage of the forming of `the postinfarction heart'.

  15. INTERACTION OF LASER RADIATION WITH MATTER: Influence of surface breakdown on the process of drilling metals with pulsed CO2 laser radiation

    NASA Astrophysics Data System (ADS)

    Arutyunyan, R. V.; Baranov, V. Yu; Bobkov, I. V.; Bol'shov, Leonid A.; Dolgov, V. A.; Kanevskiĭ, M. F.; Malyuta, D. D.; Mezhevov, V. S.

    1988-03-01

    A report is given of the influence of low-threshold surface optical breakdown, occurring under the action of short (~ 5-μs) radiation pulses from a CO2 laser, on the process of the laser drilling of metals. Data are given on the difference between the interaction of radiation pulses having the same duration but differing in shape. A study was made of the influence of the pressure of the atmosphere surrounding a target on the results of laser drilling of metals. A theoretical explanation is given of the experimental results.

  16. Absorption of the laser radiation by the laser plasma with gas microjet targets

    NASA Astrophysics Data System (ADS)

    Borisevichus, D. A.; Zabrodskii, V. V.; Kalmykov, S. G.; Sasin, M. E.; Seisyan, R. P.

    2017-01-01

    An upper limit of absorption of the laser radiation in the plasma produced in a gas jet Xe target with the average density of (3-6) × 1018 cm-3 and the effective diameter of 0.7 mm is found. It is equal to ≈50% and remains constant under any variation in this range of densities. This result contradicts both theoretical assessments that have predicted virtually complete absorption and results of earlier experiments with the laser spark in an unlimited stationary Xe gas with the same density, where the upper limit of absorption was close to 100%. An analysis shows that nonlinearity of absorption and plasma nonequilibrium lead to the reduction of the absorption coefficient that, along with the limited size of plasma, can explain the experimental results.

  17. [Modification of radiation damage to biological objects by lasers].

    PubMed

    Voskanian, K Sh; Vorozhzova, S V; Abrosimova, A N; Mitsyn, G V; Gaevskiĭ, V N

    2012-01-01

    A series of experiments had the purpose to study effects of gamma-rays 60Co (5 Gy) and the combined effects of laser 650 nm (1 mJ/cm2) and gamma-rays 60Co (5 Gy) on survivability, body mass, integument and mitotic index of marrow cells (MC) of young mice C57BL/6. Laser was applied to the mouse hairy back only. Ten months of gamma-irradiation brought death to 50% of mice; the combined irradiation killed only 30%. Starting on month six after gamma-irradiation, body mass was less in comparison with mice exposed to the combined irradiation. In addition, all mice lost body mass sharply before death. All gamma-irradiated mice were touched with grey over the period of 30 days; in 40 days, 10 of 20 mice had incipient local radiation alopecia on the back that passed fully within next month. However, all mice developed radiation ulcers on the fourth month since irradiation. Two mice formed also neck tumors. In 5 months tails fell off in 2 mice. Some grey streaks appeared on mice exposed to the combined irradiation 3 months later only; three mice remained black throughout the follow-up. Alopecia was found in three survivors in 5 months after irradiation. Mitotic activity of marrow cells obtained from mice on day 15 since exposure to lasing and combined irradiation was higher in comparison with cells from intact mice. In a year, the MC mitotic index was higher in mice exposed to the combined irradiation as compared with the gamma-irradiated mice.

  18. The impact of the choice of radiative transfer model and inversion method on the OSIRIS ozone and nitrogen dioxide retrievals

    NASA Astrophysics Data System (ADS)

    Haley, Craig; McLinden, Chris; Sioris, Christopher; Brohede, Samuel

    Key to the retrieval of stratospheric minor species information from limb-scatter measurements are the selections of a radiative transfer model (RTM) and inversion method (solver). Here we assess the impact of choice of RTM and solver on the retrievals of stratospheric ozone and nitrogen dioxide from the OSIRIS instrument using the ‘Ozone Triplet' and Differential Optical Absorption Spectroscopy (DOAS) techniques that are used in the operational Level 2 processing algorithms. The RTMs assessed are LIMBTRAN, VECTOR, SCIARAYS, and SASKTRAN. The solvers studied include the Maximum A Posteriori (MAP), Maximum Likelihood (ML), Iterative Least Squares (ILS), and Chahine methods.

  19. CONTROL OF LASER RADIATION PARAMETERS: A LiNbO3 switch for fibre lasers

    NASA Astrophysics Data System (ADS)

    Davydov, B. L.; Yagodkin, D. I.

    2005-11-01

    An electro-optical switch (modulator) based on one LiNbO3 crystal and fundamentally thermally stable is investigated. The switch is intended for controlling radiation from laser and luminescence fibre emitters. The operation principle of the modulator is described briefly, its static and pulse characteristics are measured and the temperature behaviour is studied. A switching contrast of 38 dB is obtained at a dc voltage of Uλ/2=400 V on a test device connected with isotropic single-mode fibres in the optical switching mode at a wavelength of 1060 nm. The half-wave voltage in the pulsed mode is 800 V.

  20. Surface and mineral changes of enamel with different remineralizing agents in conjunction with carbon-dioxide laser

    PubMed Central

    Mohan, Ajit George; Ebenezar, A. V. Rajesh; Ghani, Mohamed Fayas; Martina, Leena; Narayanan, Ashwin; Mony, Bejoy

    2014-01-01

    Aim: The aim of this study was to evaluate the surface/mineral changes on enamel before and after the application of acidulated phosphate fluoride (APF) gel, fluoride enhanced hydroxyapatite gel and propolis in conjunction with carbon-dioxide (CO2) laser. Materials and Methods: Crowns of 40 human maxillary central incisors were collected and were divided into four groups of 10 each: Topical fluoride application only, topical fluoride application followed by CO2 laser irradiation, CO2 laser irradiation followed by topical fluoride application and CO2 laser irradiation before and after topical fluoride application. The 10 crowns in each group was again sectioned into four equal parts of mesio-incisal, disto-incisal, mesio-cervical and disto-cervical sections rendering 40 samples in each group. Each group was again subdivided into four subgroups: Subgroup C - untreated enamel surface (control). Subgroup A - APF gel application, subgroup R - fluoride enhanced hydroxyapatite gel application and subgroup P - propolis application. The surface morphology of the test samples were analyzed by scanning electron microscopy and mineral changes by energy dispersion X-ray spectrophotometer. Results: Total mineral content is maximum in Group 4A (CO2 laser irradiation before and after APF gel application) and calcium/phosphate ratio is highest in Group 4R (CO2 laser irradiation before and after Remin-Pro application). Group 2A (APF gel application followed by CO2 laser irradiation) has the maximum fluoride retention. Conclusion: Laser irradiation of enamel through a topically applied APF gel is effective in the prophylaxis and management of dental caries. PMID:24966758

  1. Selection of linear-cavity fibre laser radiation using a reflection interferometer

    SciTech Connect

    Terentyev, V S; Simonov, V A

    2013-08-31

    We consider the use of a two-mirror multibeam reflection interferometer as a selector of linear-cavity single-mode fibre laser radiation and present experimental data on continuous wavelength tuning of an erbium-doped fibre laser. Conditions are found for single-longitudinal-mode operation of the fibre laser cavity using a reflection interferometer, with the possibility of broadband wavelength tuning. (control of laser pulse parameters)

  2. Multidisciplinary approaches to radiation-balanced lasers (MARBLE): a MURI program by AFOSR (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Sheik-Bahae, Mansoor

    2017-02-01

    An overview of the diverse research activities under the newly funded MURI project by AFOSR will be presented. The main goal is to advance the science of radiation-balanced lasers, also known as athermal lasers, in order to mitigate the thermal degradation of the high-power laser beams. The MARBLE project involves researchers from four universities and spans research activities in rare-earth doped crystals and fibers to semiconductor disc lasers.

  3. The CO2 gasdynamic laser as a high-intensity radiation facility

    NASA Technical Reports Server (NTRS)

    Lundell, J. H.; Dickey, R. R.; Otten, L. J.

    1975-01-01

    The basic theory of CO2 gasdynamic lasers is discussed and related to the design of the Ames laser, which is described in detail. Results of the experimental calibration of the laser are reported and compared with theoretical predictions, and the agreement is excellent. Finally, several applications of the laser as a radiation source for materials testing, both with and without air flow, are described.

  4. Influence of He-Ne laser radiation of pacemaker on the frog's heart function

    NASA Astrophysics Data System (ADS)

    Porozov, Yury B.; Brill, Gregory E.; Kiritchuk, Vyacheslav F.

    1997-02-01

    In experiments on isolated amphibian hearts changes in photoreactivity of pacemaker cells under the influence of He-Ne laser radiation in different phases of the heart cycle were studied. The specificity of heart photoreaction, peculiarities of relaxation period after laser light action and laser modification of hypodynamic depression development were revealed. Adaptation of pacemaker cells to the He-Ne laser exposure was observed.

  5. Optical Protection Filters for Harmful Laser Beams and UV Radiation

    NASA Astrophysics Data System (ADS)

    Azim M., Osama A.

    2007-02-01

    Due to the rapid growth of radiation protection applications in various devices and instruments, it is essential to use suitable filters for eye protection of the personal working in the radiation field. Different protection filters were produced to protect from four laser beam wavelengths (at 532nm, 632.8nm, 694nm and 1064nm) and block three UV bands (UVA, UVB, and UVC). The design structure of the required dielectric multilayer filters used optical thin film technology. The computer analyses of the multilayer filter formulas were prepared using Macleod Software for the production filter processes. The deposition technique was achieved on optical substrates (Glass BK-7 and Infrasil 301) by dielectric material combinations including Dralo (mixture of oxides TiO2/Al2O3), and Lima (mixture of oxides SiO2/Al2O3); deposition by an electron beam gun. The output transmittance curves for both theoretical and experimental values of all filters are presented. To validate the suitability for use in a `real world', rather than laboratory test application, full environmental assessment was also carried out. These filters exhibited high endurance after exposing them to the durability tests (adhesion, abrasion resistance and humidity) according to military standards MIL-C-675C and MIL-C-48497A.

  6. EFFECTS OF LASER RADIATION ON MATTER: Melting and thermocapillary convection under the action of pulsed laser radiation with an inhomogeneous spatial distribution

    NASA Astrophysics Data System (ADS)

    Uglov, A. A.; Smurov, I. Yu; Gus'kov, A. G.; Aksenov, L. V.

    1990-08-01

    A theoretical study is reported of melting and thermocapillary convection under the action of laser radiation with a nonmonotonic spatial distribution of the power density. An analysis is made of changes in the geometry of the molten bath with time. The transition from a nonmonotonic boundary of a melt, corresponding to the spatial distribution of the radiation, to a monotonic one occurs in a time of the order of 1 ms when the power density of laser radiation is 105 W/cm2. The vortex structure of the flow in the molten bath is governed by the spatial distribution of the laser radiation in such a way that each local power density maximum corresponds to two vortices with oppositely directed velocity components.

  7. CONTROL OF LASER RADIATION PARAMETERS: Effect of the 129I impurity on the radiation frequency of a stabilised He — Ne/127I2 laser

    NASA Astrophysics Data System (ADS)

    Negriyko, Anatolii M.; Boyko, Oleksei V.; Kachalova, Nataliya M.; Khodakovskii, Vladimir M.

    2004-05-01

    The radiation frequency of a He — Ne/127I2 laser stabilised to the hyperfine structure component of molecular iodine exhibits shifts caused by the presence of impurities in the iodine cell. The specific effect of the 129I impurity on the radiation frequency of a stabilised laser is considered. It is shown that even for a 0.25 % concentration of 129I, the frequency shift in a He — Ne/127I2 laser caused by this isotope plays a decisive role. To exclude the possible effect of other iodine isotopes on the accuracy of reproducibility of the frequency of metrological lasers, it is expedient to carry out the laser fluorescence test of the cells to check for the presence of heteroisotopic molecular iodine impurity.

  8. Comparison of a CO2 (Carbon Dioxide) Laser and Tissue Glue with Conventional Surgical Techniques in Circumcision

    PubMed Central

    Mungnirandr, Akkrapol; Wiriyakamolphan, Suwanna; Ruangtrakool, Ravit; Ngerncham, Monawat; Tumrongsombutsakul, Sureerat; Leumcharoen, Bungorn

    2015-01-01

    Introduction: CO2 (Carbon Dioxide) laser application in circumcision, for cutting and coagulation, has been reported to have excellent results. Also, tissue glue has been reported to have advantages over sutures for approximation of wound edges. Most previous studies focused on comparisons between CO2 laser and scalpel, or between tissue glue and sutures. This study prospectively compared the results and complications CO2 laser and tissue glue, with standard surgical techniques in circumcision. Methods: Thirty boys were prospectively divided into two groups. Group 1 (n = 17) underwent circumcision by scalpel with approximation of the wound edges using chromic catgut sutures. Group 2 (n = 13) underwent circumcision with CO2 laser and approximation of the wound edges using tissue glue. Patient age, indications for surgery, operative time, wound swelling, bleeding, wound infection, local irritation, pain score, and cosmetic appearance were recorded. Results: Group 1 had a significantly longer operative time (P= 0.011), higher rate of local irritation (P= 0.016), and poorer cosmetic appearance (P< 0.001) than group 2. Bleeding only occurred in one patient in group 1. There were no significant differences in pain score, wound infection rate, or cost of surgery between the two groups. Conclusions: CO2 laser and tissue glue have advantages over standard surgical techniques in circumcision, with a significantly shorter operative time, lower rate of local irritation, and better cosmetic appearance. The cost of surgery is similar between the two groups. PMID:25699165

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

    PubMed

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

    2016-04-01

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

  10. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Laser—ultrasonic formation of melts of high-speed tool steels

    NASA Astrophysics Data System (ADS)

    Gureev, D. M.

    1994-09-01

    A study was made of the influence of ultrasonic vibrations on the processes of heat and mass transfer, and of structure formation during ultrafast crystallisation of laser melts of T1 high-speed tool steel. Acoustic flows which appeared in laser melts effectively smoothed out the temperature inhomogeneities and flattened the relief of the molten surface even when the laser radiation acted for just ~1 ms. The transformation of the mechanical energy of ultrasonic vibrations into heat increased the depth of the laser melt baths and suppressed crack formation. The observed changes in the structural and phase composition appeared as a change in the microhardness of the solidified laser melts. The geometry of coupling of ultrasound into a laser melt influenced the changes in the microhardness, suggesting a need for a more detailed analysis of the structure formation processes in the course of ultrafast crystallisation of laser melts in an ultrasonic field.

  11. Development of a tunable UV laser system synchronizing precisely with synchrotron radiation pulses from UVSOR.

    PubMed

    Mizutani, M; Tokeshi, M; Hiraya, A; Mitsuke, K

    1997-01-01

    A mode-locked Ti:sapphire laser is made to oscillate at the frequency of the UVSOR storage ring, 90.115 MHz, in a multi-bunch operation mode. The third harmonic of the laser is available in the wavelength range 243-280 nm. Synchrotron radiation from an undulator is monochromated by a grazing-incidence monochromator and introduced coaxially with the laser. The temporal profile of the photon pulses is monitored in situ by a luminescing substance/photomultiplier combination. The delay timing between the laser and synchrotron radiation can be changed from 0 to 11 ns by adjusting an electronic module that provides phase-locked loop stabilization of the laser pulse. The reliability and feasibility of this laser-synchrotron radiation combination technique are demonstrated by applying pump-probe experiments to two physical systems. The first system is photodissociation of iodomethane (CHA) with a laser photon, followed by photoionization of I and CH3 fragments with synchrotron radiation. The second, two-photon ionization of He atoms, is studied as the prototype of a time-resolved experiment. The He+ signal counts as a function of the laser-synchrotron radiation delay are found to be enhanced in a narrow time window, which can be interpreted in terms of a short lifetime of the resonant state, He*(1s2p 1P), produced by primary synchrotron radiation excitation.

  12. LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Modification of biological objects in water media by CO2-laser radiation

    NASA Astrophysics Data System (ADS)

    Baranov, G. A.; Belyaev, A. A.; Onikienko, S. B.; Smirnov, S. A.; Khukharev, V. V.

    2005-09-01

    The modification of biological objects (polysaccharides and cells) by CO2-laser radiation in water added drop by drop into the interaction region is studied theoretically and experimentally. Calculations are performed by using the models describing gas-dynamic and heterogeneous processes caused by absorption of laser radiation by water drops. It is found experimentally that the laser modification of polysaccharides leads to the formation of low-molecular derivatives with immunostimulating properties. A dose of the product of laser activation of the yeast culture Saccharamyces cerevisiae prevented the development of a toxic emphysema in mice and protected them against lethal grippe and also prevented a decrease of survival rate, increased the average life, and prevented the development of metabolic and immune disorders in mice exposed to sublethal gamma-radiation doses.

  13. Laser damage of skin by 1540-nm Er-glass laser radiation: impact on laser safety standards

    NASA Astrophysics Data System (ADS)

    Lukashev, Alexei V.; Denker, Boris I.; Pashinin, Pavel P.; Sverchkov, Sergey E.

    1996-11-01

    The skin response was studied for different radiant exposure of short and long laser pulses and reaction to multipulse action using Er-glass laser radiation. Lesion ranging from a mild erythema to tissue coagulation were produced on porcine skin. Radiant exposure producing 50 percent probability of a particular grade of lesion were established. A dependence of ED50 of minimum erythema versus number of pulses and beam cross section were studied. The dose-response relationship for producing different grades of burns were determined for energy densities of single laser pulse within the range 0.5- 35 J/cm2 and pulse duration 100 ns and 3 ms. The single pulse dose in a chain of repetitive pluses producing minimum erythema were determined for 2n(n equals 1-6 pulses). The minimum reaction of skin on laser irradiance were studied for different beam diameter. The reaction of skin is mostly considered as local super heating. The data obtained are adequate to update safety standards for cutaneous injury within thee ranges of radiant exposure and beam spotsize.

  14. Terahertz radiation generation and shape control by interaction of array Gaussian laser beams with plasma

    NASA Astrophysics Data System (ADS)

    Bakhtiari, Farhad; Golmohammady, Shole; Yousefi, Masoud; Ghafary, Bijan

    2016-12-01

    In the present paper, a scheme for generation of terahertz (THz) radiation in electron-neutral collisional plasma based on beating of two Gaussian laser array beams has been proposed. It is shown that the efficiency of THz radiation based on the Gaussian laser array beams can be enhanced drastically in comparison with the efficiency of THz radiation based on the Gaussian one. Furthermore, the producing THz radiation by the Gaussian laser array beams, which has an exclusive field profile, is affected by some array structure parameters. It can also be used to overcome the negative consequences of electron neutral collisions in plasma, which may be occurring in the THz radiation generation process. Optimizing the collisional plasma, laser beams and array structure parameters, THz radiation efficiency up to 0.07% can be obtained in our scheme which is about three times greater than the maximum efficiency obtained for standard (single) Gaussian laser beam. Also, considering the electrostatic energy channel in solving the THz wave equation, and reduction of THz radiation efficiency to 0.054%, in this assumption, the ratio between the efficiency of Gaussian laser array beams and standard Gaussian laser beam remained unchanged.

  15. Modelling of micromachining of human tooth enamel by erbium laser radiation

    SciTech Connect

    Belikov, A V; Skrypnik, A V; Shatilova, K V

    2014-08-31

    We consider a 3D cellular model of human tooth enamel and a photomechanical cellular model of enamel ablation by erbium laser radiation, taking into account the structural peculiarities of enamel, energy distribution in the laser beam cross section and attenuation of laser energy in biological tissue. The surface area of the texture in enamel is calculated after its micromachining by erbium laser radiation. The influence of the surface area on the bond strength of enamel with dental filling materials is discussed. A good correlation between the computer simulation of the total work of adhesion and experimentally measured bond strength between the dental filling material and the tooth enamel after its micromachining by means of YAG : Er laser radiation is attained. (laser biophotonics)

  16. Temperature distribution simulation of the human eye exposed to laser radiation.

    PubMed

    Mirnezami, Seyyed Abbas; Rajaei Jafarabadi, Mahdi; Abrishami, Maryam

    2013-01-01

    Human eye is a sensitive part of human body with no direct protection and due to its lack of protection against the external heat waves, studying the temperature distribution of heat waves on the human eye is of utmost importance. Various lasers are widely used in medical applications such as eye surgeries. The most significant issue in the eye surgeries with laser is estimation of temperature distribution and its increase in eye tissues due to the laser radiation intensity. Experimental and invasive methods to measure the eye temperature usually have high risks. In this paper, human eye has been modeled through studying the temperature distribution of three different laser radiations, using the finite element method. We simulated human eye under 1064 nm Neodymium-Doped Yttrium Aluminium Garnet (Nd: YAG) laser, 193 nm argon fluoride (ArF) excimer laser, and 1340 nm Neodymium doped Yttrium Aluminum Perovskite (Nd: YAP) laser radiation. The results show that these radiations cause temperature rise in retina, lens and cornea region, which will in turn causes serious damages to the eye tissues. This simulation can be a useful tool to study and predict the temperature distribution in laser radiation on the human eye and evaluate the risk involved in using laser to perform surgery.

  17. Temperature Distribution Simulation of the Human Eye Exposed to Laser Radiation

    PubMed Central

    Mirnezami, Seyyed Abbas; Rajaei Jafarabadi, Mahdi; Abrishami, Maryam

    2013-01-01

    Introduction: Human eye is a sensitive part of human body with no direct protection and due to its lack of protection against the external heat waves, studying the temperature distribution of heat waves on the human eye is of utmost importance. Various lasers are widely used in medical applications such as eye surgeries. The most significant issue in the eye surgeries with laser is estimation of temperature distribution and its increase in eye tissues due to the laser radiation intensity. Experimental and invasive methods to measure the eye temperature usually have high risks. Methods: In this paper, human eye has been modeled through studying the temperature distribution of three different laser radiations, using the finite element method. We simulated human eye under 1064 nm Neodymium-Doped Yttrium Aluminium Garnet (Nd: YAG) laser, 193 nm argon fluoride (ArF) excimer laser, and 1340 nm Neodymium doped Yttrium Aluminum Perovskite (Nd: YAP) laser radiation. Results: The results show that these radiations cause temperature rise in retina, lens and cornea region, which will in turn causes serious damages to the eye tissues. Conclusion: This simulation can be a useful tool to study and predict the temperature distribution in laser radiation on the human eye and evaluate the risk involved in using laser to perform surgery. PMID:25606327

  18. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Laser plume spectroscopy. 2. Graphite yttrium-stabilised and zirconium oxide targets

    NASA Astrophysics Data System (ADS)

    Osipov, V. V.; Solomonov, V. I.; Platonov, V. V.; Snigireva, O. A.; Ivanov, M. G.; Lisenkov, V. V.

    2005-07-01

    Spectral and kinetic properties of a plume formed in the vicinity of a graphite and a pressed yttrium-stabilised zirconium oxide (YSZ) powder targets irradiated in air by a 10.6-μm pulsed CO2 laser with a peak power of 1.5-9 kW at room temperature are studied. The plume propagated at right angles to the target surface and at an angle of 45° to the laser radiation. The spectral and kinetic characteristics of its luminescence were measured discretely along the entire length of the plume. It is shown that the YSZ plume as well as the graphite plume is a flux of nonequilibrium gaseous plasma at a temperature of about 4.7-3.1 kK, in which a luminescence of YO and ZrO radicals is excited.

  19. EFFECT OF LASER LIGHT ON MATTER. LASER PLASMAS: Multiphoton coloration of lead silicate glasses by high-power laser radiation

    NASA Astrophysics Data System (ADS)

    Efimov, O. M.; Matveev, Yu A.; Mekryukov, A. M.

    1994-04-01

    A study was made of the mechanism of the formation of colour centres by the exposure of lead silicate glasses to high-power laser radiation. The long-wavelength mobility edge (>5.8 eV) of charge carriers in these glasses was located well above the fundamental absorption edge (3.5 eV), so that coloration was observed only when the glass matrix experienced multiphoton ionisation. The newly formed colour centres make the main contribution to the change in the transmission directly during the action of nanosecond laser pulses. An estimate was obtained of the three-photon absorption coefficient of TF10 glass at the wavelength of 527 nm.

  20. Plasma formation on a metal surface under combined action of laser and microwave radiation

    SciTech Connect

    Gavrilyuk, A P; Shaparev, N Ya

    2013-10-31

    By means of numerical modelling of the combined effect of laser (1.06 mm) and microwave (10{sup 10} – 10{sup 13} s{sup -1}) radiation on the aluminium surface in vacuum it is shown that the additional action of microwave radiation with the frequency 10{sup 12} s{sup -1} provides complete ionisation of the metal vapour (for the values of laser radiation duration and intensity used in the calculations), while in the absence of microwave radiation the vapour remains weakly ionised. The mathematical model used accounts for the processes, occurring in the condensed phase (heat conduction, melting), the evaporation and the kinetic processes in the resulting vapour. (interaction of laser radiation with matter. laser plasma)

  1. On the structure of quasi-stationary laser ablation fronts in strongly radiating plasmas

    NASA Astrophysics Data System (ADS)

    Basko, M. M.; Novikov, V. G.; Grushin, A. S.

    2015-05-01

    The effect of strong thermal radiation on the structure of quasi-stationary laser ablation fronts is investigated under the assumption that all the laser flux is absorbed at the critical surface. Special attention is paid to adequate formulation of the boundary-value problem for a steady-state planar ablation flow. The dependence of the laser-to-x-ray conversion efficiency ϕ r on the laser intensity IL and wavelength λL is analyzed within the non-equilibrium diffusion approximation for radiation transfer. The scaling of the main ablation parameters with IL and λL in the strongly radiative regime 1 - ϕ r ≪ 1 is derived. It is demonstrated that strongly radiating ablation fronts develop a characteristic extended cushion of "radiation-soaked" plasma between the condensed ablated material and the critical surface, which can efficiently suppress perturbations from the instabilities at the critical surface.

  2. Cross modulation method of transformation of the spatial coherence of pulsed laser radiation in a nonlinear medium

    SciTech Connect

    Kitsak, M A; Kitsak, A I

    2008-04-30

    The cross modulation method of transformation of the spatial coherence of low-power pulsed laser radiation in a nonlinear medium is proposed. The method is realised experimentally in a multimode optical fibre. The estimates of the degree of spatial coherence of radiation subjected to the phase cross modulation demonstrated the high efficiency of this radiation decorrelation mechanism. (control of laser radiation parameters)

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

    DTIC Science & Technology

    1978-10-17

    equal that of the plasma. Certain substances are actively transported by the epithelial cells and, as a result, their -ccncentraticn in the aqueous...energy of the lens is expended in these syntheses. ’he arLno acids are actively transported across the !en-s etitheliun into the lens fram the aqueous...that of noral acueous hi-cr). Ar ..... n of the b.lood flow tt region would be reflected ,y a ecrement of ascortic acid a vilable for 145 transport

  4. Nd:YAG laser systems with radiation delivery by thin hollow waveguides

    NASA Astrophysics Data System (ADS)

    Nemec, Michal; Jelínková, Helena; Šulc, Jan; Miyagi, Mitsunobu; Iwai, Katsumasa; Shi, Yi-Wei; Matsuura, Yuji

    2008-04-01

    The goal of the work was the investigation of hollow waveguide utilization for near infrared laser radiation delivery. As basic delivery unit, a new thin cyclic olefin polymer coated silver hollow glass waveguide with diameters 100/190 μm or 250/360 μm and length up to 20 cm was used. Four near infrared laser sources were based on the Nd:YAG crystals. The first one - Nd:YAG laser passively Q-switched by LiF:F 2- saturable absorber - was coherently pumped by Alexandrite radiation. The system generated 1.06 μm wavelength radiation with 6 ns length of pulse and 0.7 mJ maximum output energy. The second and third laser systems were compact longitudinally diode pumped Nd:YAG lasers generating radiation at wavelength 1.06 μm and 1.44 μm. These lasers were operating in a free-running regime under pulsed pumping (pulse repetition rate 50 Hz). Mean output power 160 mW (90 mW) with pulse length 0.5 ms (1 ms) was generated at wavelength 1.06 μm (1.44 μm). The last radiation source was the Nd:YAG/V:YAG microchip laser pumped by laser diode and generating the radiation at 1.34 μm wavelength. The output power, pulse length, and repetition rate were 25 mW, 6 ns, and 250 Hz, respectively. All lasers were generating beam with gaussian TEM 00 profile. These radiations were focused into thin a waveguide and delivery radiation characteristics were investigated. It was recognized that the output spatial structure is significantly modified in all cases. However a compact delivery system can be useful for near infrared powerful radiation delivery in some special technological and medical applications.

  5. Automatic Resonator Alignment and Power Stabilization of High Power Carbon Dioxide Lasers

    NASA Astrophysics Data System (ADS)

    Akitt, Dale Richard

    1992-01-01

    The high power carbon dioxide laser has become a very important tool in the area of industrial materials processing. This is due primarily to the enormous optical intensities which the device can attain. Unfortunately, it has proved increasingly difficult to construct machines capable of maintaining a consistently uniform output beam at elevated power levels, for extended periods. These difficulties are often attributed to thermal distortion of the resonator optics. Because of this fact, researchers have invested considerable effort in the construction of water cooled, thermally stable optical benches, upon which to mount the resonator components. This approach is very expensive, and has provided only a partial solution to the problem. A different approach, and the subject of this thesis, is to construct a feedback control system which actively re-positions the optical elements, so as to maintain optimum resonator alignment. Preliminary experiments demonstrated that this concept was indeed feasible. In this first study, a circular array of small thermistors was utilized as the feedback element. Indicators of mode uniformity in the vertical and horizontal directions were extracted from the array using electronic techniques. A relay type controller monitored these error measures and subsequently activated a pair of motor-micrometers fitted to one of the primary resonator mirrors. Although this thermistor-based system demonstrated the viability of the concept, the sensor array's slow response limited its performance. Subsequent experiments utilizing high speed pyroelectric detectors in place of the thermistors solved the problem. The next series of experiments was dedicated to finding a method of simultaneously aligning both primary resonator mirrors. This was accomplished by configuring the sensor array to monitor not only beam uniformity, but also beam position. A new controller was then developed which adjusted one mirror based on the position of the output beam

  6. EFFECT OF LASER LIGHT ON MATTER. LASER PLASMAS: Optical breakdown of quartz glass by XeF laser radiation

    NASA Astrophysics Data System (ADS)

    Amosov, A. V.; Barabanov, V. S.; Gerasimov, S. Yu; Morozov, Nikolai V.; Sergeev, P. B.; Stepanchuk, V. N.

    1994-04-01

    The bulk optical strengths of KU1 and KUVI quartz glasses were determined for pulses of 85 ns duration at the wavelength of 353 nm. The damage thresholds of these materials were the same and amounted to 280 GW cm-2. The optical breakdown thresholds of KU1 at λ = 248 nm and λ = 193 nm, obtained earlier for the same samples under otherwise identical conditions, were used together with the present results to plot the wavelength dependence of the damage threshold of this material. These results showed that nonlinear absorption is the main mechanism responsible for damage to quartz glass in high-intensity ultraviolet laser radiation fields.

  7. Effect of Surface Treatment with Carbon Dioxide (CO2) Laser on Bond Strength between Cement Resin and Zirconia

    PubMed Central

    Kasraei, Shahin; Atefat, Mohammad; Beheshti, Maryam; Safavi, Nassimeh; Mojtahedi, Maryam; Rezaei-Soufi, Loghman

    2014-01-01

    Introduction: Since it is not possible to form an adequate micromechanical bond between resin cement and zirconia ceramics using common surface treatment techniques, laser pretreatment has been suggested for zirconia ceramic surfaces. The aim of this study was to evaluate the effect of Carbon Dioxide (CO2) Laser treatment on shear bond strength (SBS) of resin cement to zirconia ceramic. Methods: In this in vitro study thirty discs of zirconia with a diameter of 6 mm and a thickness of 2 mm were randomly divided into two groups of 15. In the test group the zirconia disc surfaces were irradiated by CO2 laser with an output power of 3 W and energy density of 265.39 j/cm2. Composite resin discs were fabricated by plastic molds, measuring 3 mm in diameter and 2 mm in thickness and were cemented on zirconia disk surfaces with Panavia F2.0 resin cement (Kuraray Co. Ltd, Osaka, Japan). Shear bond strength was measured by a universal testing machine at a crosshead speed of 0.5 mm/min. The fracture type was assessed under a stereomicroscope at ×40. Surface morphologies of two specimens of the test group were evaluated under SEM before and after laser pretreatment. Data was analyzed by paired t-test (p value < 0.05). Results: The mean SBS values of the laser and control groups were 12.12 ± 3.02 and 5.97 ± 1.14 MPa, respectively. Surface treatment with CO2 laser significantly increased SBS between resin cement and zirconia ceramic (p value = 0.001). Conclusion: Under the limitations of this study, surface treatment with CO2 laser increased the SBS between resin cement and the zirconia ceramic. PMID:25653809

  8. ARTICLES: Physical laws governing the interaction of pulse-periodic CO2 laser radiation with metals

    NASA Astrophysics Data System (ADS)

    Vedenov, A. A.; Gladush, G. G.; Drobyazko, S. V.; Pavlovich, Yu V.; Senatorov, Yu M.

    1985-01-01

    It is shown theoretically and experimentally that the efficiency of welding metals with a pulse-periodic CO2 laser beam of low duty ratio, at low velocities, can exceed that of welding with cw lasers and with electron beams. For the first time an investigation was made of the influence of the laser radiation parameters (energy and frequency) and of the welding velocity on the characteristics of the weld and on the shape of the weldpool. The influence of the laser radiation polarization on the efficiency of deep penetration was analyzed.

  9. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Laser ablation plume dynamics in nanoparticle synthesis

    NASA Astrophysics Data System (ADS)

    Osipov, V. V.; Platonov, V. V.; Lisenkov, V. V.

    2009-06-01

    The dynamics of the plume ejected from the surface of solid targets (YSZ, Nd:YAG and graphite) by a CO2 laser pulse with a duration of ~500 μs (at the 0.03 level), energy of 1.0-1.3 J and peak power of 6-7 kW have been studied using high-speed photography of the plume luminescence and shadow. The targets were used to produce nanopowders by laser evaporation. About 200 μs after termination of the pulse, shadowgraph images of the plumes above the YSZ and Nd:YAG targets showed dark straight tracks produced by large particles. The formation of large (~10 μm) particles is tentatively attributed to cracking of the solidified melt at the bottom of the ablation crater. This is supported by the fact that no large particles are ejected from graphite, which sublimes without melting. Further support to this hypothesis is provided by numerical 3D modelling of melt cooling in craters produced by laser pulses of different shapes.

  10. Radiation from laser accelerated electron bunches: Coherent terahertz and femtosecond X-rays

    SciTech Connect

    Leemans, W.P.; Esarey, E.; van Tilborg, J.; Michel, P.A.; Schroeder, C.B.; Toth, Cs.; Geddes, C.G.R.; Shadwick, B.A.

    2004-10-01

    Electron beam based radiation sources provide electromagnetic radiation for countless applications. The properties of the radiation are primarily determined by the properties of the electron beam. Compact laser driven accelerators are being developed that can provide ultra-short electron bunches (femtosecond duration) with relativistic energies reaching towards a GeV. The electron bunches are produced when an intense laser interacts with a dense plasma and excites a large amplitude plasma density modulation (wakefield) that can trap background electrons and accelerate them to high energies. The short pulse nature of the accelerated bunches and high particle energy offer the possibility of generating radiation from one compact source that ranges from coherent terahertz to gamma rays. The intrinsic synchronization to a laser pulse and unique character of the radiation offers a wide range of possibilities for scientific applications. Two particular radiation source regimes are discussed: Coherent terahertz emission and x-ray emission based on betatron oscillations and Thomson scattering.

  11. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Photoionisation of a helium atom involving autoionisation states coupled by a circularly polarised laser field

    NASA Astrophysics Data System (ADS)

    Gryzlova, E. V.; Magunov, A. I.; Rotter, I.; Strakhova, S. I.

    2005-01-01

    The rotating wave approximation is used to obtain parametric expressions for the resonance cross section for the atomic ground state ionisation by linearly polarised probe radiation in the vicinity of an autoionisation state coupled resonantly to another autoionisation state through circularly polarised laser radiation. Calculations are made for the 2s2p 1P and 2s3d 1D states of the helium atom. It is shown that the structure of the photoionisation cross-section spectrum formed for circularly polarised laser radiation differs qualitatively from the structure formed in the case of linear polarisation. The dependence of this structure on the intensity and frequency of laser radiation and the direction of polarisation of the probe radiation is studied.

  12. Depolarization of radiation from high-power neodymium lasers and second harmonic generation of partly depolarized radiation

    SciTech Connect

    Arifzhanov, S.B.; Gulamov, A.A.; Redkorechev, V.I.; Usmanov, T.

    1985-07-01

    A theoretical analysis is made of two mechanisms (linear and nonlinear) of depolarization of radiation emitted by high-power solid-state glass lasers: these mechanisms are anisotropy-induced in the active elements and a nonlinear rotation of the polarization ellipse. In the cases of linear and circular polarization of practical interest, a qualitative and numerical analysis is made of the influence of depolarization of the radiation on second harmonic generation by the second type of interaction in KDP crystals. It is shown that in a field of partly depolarized radiation the second harmonic generation efficiency is limited mainly by depolarization of the radiation.

  13. A Novel Spherical Hohlraum Design with Tetrahedral 4 Laser Entrance Holes and High Radiation Performance

    NASA Astrophysics Data System (ADS)

    Huang, Yunbao; Jing, Longfei; Jiang, Shaoen

    2016-10-01

    As usual cylindrical hohlraum with double laser ring cones may lead to serious CBET, and LPI effect, spherical hohlraum with octahedral 6 LEHs and single laser ring cone is investigated and presented to achieve higher radiation symmetry during the fusion process. However, it has several potential problems such as the long run distance and the close distance between the spot and their closet LEH for the laser beams, smaller space is left for diagnose, and the assembly of centrally located capsule. In this paper, based on view-factor transportation model, we investigate the radiation symmetry and the drive temperature on the centrally located capsule in the spherical hohlraum with tetrahedral 4 LEHs and single laser ring cone, since there is more available space for laser disposition and diagnose. Then, such target is optimized on the laser beam pointing direction and shape sizes to achieve high radiation performance, or the radiation symmetry and drive temperature on the capsule. Finally, a novel spherical hohlraum with optimal laser beam pointing and shape size has been demonstrated to have almost similar radiation symmetry (the radiation asymmetry variation is no more than 0.2%), and higher drive temperature (the temperature has been increased by 1.73%, and additional 133 KJ energy of 2MJ energy for fusion can be utilized).

  14. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA Annealing of induced absorption in quartz glasses by ArF laser radiation

    NASA Astrophysics Data System (ADS)

    Sergeev, P. B.; Sergeev, A. P.

    2010-11-01

    Annealing of individual bands of electron-beam-induced absorption (IA) in the region of 150 — 400 nm in KS-4V, KU-1, and Corning 7980 (ArF Grade) quartz glasses by ArF laser radiation is studied. It is shown that the phototransformation of the IA spectra occurs mainly due to a significant decrease in the amplitudes of bands at λ = 183.5, 213, and 260 nm. The role played by interstitial oxygen, hydrogen, and chlorine in the formation and relaxation of glass defects is considered.

  15. Spectral characteristics of VUV radiation emitted by a laser plume

    SciTech Connect

    Khater, Mohamed A.

    2013-12-16

    We study some experimental parameters and conditions of laser-generated plasma plumes using time-integrated, spatially resolved emission spectroscopy in the VUV range. The influences of the laser focusing lens type, laser wavelength, as well as laser pulse energy on the emission characteristics of the laser plasmas are investigated. The aim of the work is to improve the detection capability of the laser-induced plasma spectroscopy (LIPS) technique. The results obtained demonstrate a set of optimum conditions for maximum spectral line intensities and signal-to-background ratios of laser-produced plasmas in the VUV regime.

  16. EFFECT OF LASER LIGHT ON MATTER. LASER PLASMAS: Optical strength of mirrors on fluorite substrates subjected to cw radiation from a chemical CO laser

    NASA Astrophysics Data System (ADS)

    Dudkin, V. A.; Rukhin, V. B.

    1994-02-01

    Optimisation of the energy characteristics of a chemical CO laser revealed damage to the optical resonator mirrors. Estimates indicated that when the power density of the incident cw laser radiation was 2-2.5 kW cm-2 the induced thermoelastic stresses could reach the damage threshold of mirrors on fluorite substrates.

  17. Evaluation of a technique of nitrogen insufflation to decrease plastic endotracheal tube cuff flammability during carbon dioxide laser surgery.

    PubMed

    Sosis, M B

    1993-01-01

    To determine whether nitrogen insufflation reduces the laser-induced combustibility of polyvinyl chloride (PVC) endotracheal tube cuffs. Research laboratory of a metropolitan, university-affiliated medical center. A plastic catheter was fastened along the shafts of 10 PVC endotracheal tubes with self-adhesive copper foil tape down to a level just above the cuff. The modified endotracheal tubes were inserted into graduated cylinders and flushed with oxygen. The cuffs were then inflated with air, and a carbon dioxide (CO2) laser was aimed at them. Five of the modified endotracheal tubes had 10 L/min of nitrogen insufflated via the plastic tube. The laser ignited only 1 of the cuffs insufflated with nitrogen; however, all 5 of the modified endotracheal tubes that were not insufflated burned (p < 0.05). Nitrogen insufflation decreases CO2 laser-induced PVC endotracheal tube cuff combustibility. However, clinical applications of this technique should be undertaken with caution, as the administration of a hypoxic mixture may be possible.

  18. The Effect of Carbon Dioxide (CO2) Laser on Sandblasting with Large Grit and Acid Etching (SLA) Surface.

    PubMed

    Foroutan, Tahereh; Ayoubian, Nader

    2013-01-01

    The purpose of this study was to investigate the effect of 6W power Carbon Dioxide Laser (CO2) on the biologic compatibility of the Sandblasting with large grit and acid etching (SLA) titanium discs through studying of the Sarcoma Osteogenic (SaOS-2) human osteoblast-like cells viability. Sterilized titanium discs were used together with SaOS-2 human osteoblast-like cells. 6 sterilized SLA titanium discs of the experimental group were exposed to irradiation by CO2 laser with a power of 6W and 10.600nm wavelength, at fixed frequency of 80Hz during 45 seconds in both pulse and non-contact settings. SaOS-2 human osteoblast-like cells were incubated under 37°C in humid atmosphere (95% weather, 5% CO2) for 72 hours. MTT test was performed to measure the ratio level of cellular proliferation. The results indicated that at 570nm wavelength, the 6W CO2 laser power have not affected the cellular viability. CO2 laser in 6w power has had no effect on the biologic compatibility of the SLA titanium surface.

  19. Which is more effective for pain relief during fractionated carbon dioxide laser treatment: EMLA cream or forced cold air anesthesia?

    PubMed

    Sari, Elif; Bakar, Bulent

    2017-07-28

    The aim of this study was to compare the effectiveness of a eutectic mixture of local anesthetic (EMLA) cream and forced cold air anesthesia (FCAA) on pain control during ablative fractionated carbon dioxide (CO2) laser treatment. Fifteen volunteers participated in this prospective, controlled, split-face clinical study. EMLA cream was applied 60 minutes before the laser procedure on half of the face, and FCAA was performed on each subunit of the other half of the face. The laser procedure was performed on each half of the face. Patients rated their pain during the procedure using a pain scale scored from 0-10. Both doctor and nurse rated patient discomfort during the procedure using a scale scored from 0-10. The pain scores associated with both EMLA and FCAA sides of the face were compared statistically. Patient pain scores and discomfort scores detected by doctor and nurse were not statistically different between EMLA and FCAA. There was no statistically significant difference between males and females. Instead of using EMLA, FCAA-which can be applied in a shorter time-may be a cost-effective, simple, and safe local anesthesia method used in the ablative fractionated CO2 laser procedure.

  20. A Novel Spherical Hohlraum Design with Tetrahedral 4 Laser Entrance Holes and High Radiation Performance

    NASA Astrophysics Data System (ADS)

    Jing, Longfei; Huang, Yunbao; Jiang, Shaoen; Li, Haiyan; Huang, Tianxuan; Ding, Yongkun

    2016-10-01

    As usual cylindrical hohlraum with double laser ring cones may lead to serious CBET effect, spherical hohlraum with octahedral 6 LEHs and single laser ring cone is presented to achieve higher radiation symmetry during the fusion process. However, it has several potential problems such as the long run distance, smaller space is left for diagnose, and the assembly of centrally located capsule. In this paper, we investigate the radiation performance, i.e., radiation symmetry and drive temperature on the capsule in the spherical hohlraum with tetrahedral 4 LEHs and single laser ring cone, since there is more available space for laser disposition and diagnose. Then, such target is optimized on the laser beam pointing direction and shape sizes to achieve high radiation performance, or the radiation symmetry and drive temperature on the capsule. Finally, a novel spherical hohlraum with optimal laser beam pointing and shape size has been demonstrated to have almost similar radiation symmetry (the radiation asymmetry variation is no more than 0.2%), and higher drive temperature (the temperature has been increased by 1.73%, and additional 133 KJ energy of 2MJ energy for fusion can be utilized).. This work was supportedby NSAF#U1430124, and NSFC#51375185, #51405177, #11475154.

  1. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Physics of the plasma corona in the problem of laser controlled thermonuclear fusion

    NASA Astrophysics Data System (ADS)

    Andreev, N. E.; Gorbunov, Leonid M.; Tikhonchuk, Vladimir T.

    1994-09-01

    A brief analysis is made of the most important nonlinear processes which result from the interaction of laser radiation with thermonuclear targets. lt is shown that problems in the physics of the plasma corona should be an essential part of any programme of research on laser controlled thermonuclear fusion. A list is given of the problems that have to be solved first before going to the next level of laser energies.

  2. Dichromatic and monochromatic laser radiation effects on survival and morphology of Pantoea agglomerans

    NASA Astrophysics Data System (ADS)

    Thomé, A. M. C.; Souza, B. P.; Mendes, J. P. M.; Soares, L. C.; Trajano, E. T. L.; Fonseca, A. S.

    2017-05-01

    Despite the beneficial effects of low-level lasers on wound healing, their application for treatment of infected injuries is controversial because low-level lasers could stimulate bacterial growth exacerbating the infectious process. Thus, the aim of this work was to evaluate in vitro effects of low-level lasers on survival, morphology and cell aggregation of Pantoea agglomerans. P. agglomerans samples were isolated from human pressure injuries and cultures were exposed to low-level monochromatic and simultaneous dichromatic laser radiation to study the survival, cell aggregation, filamentation and morphology of bacterial cells in exponential and stationary growth phases. Fluence, wavelength and emission mode were those used in therapeutic protocols for wound healing. Data show no changes in morphology and cell aggregation, but dichromatic laser radiation decreased bacterial survival in exponential growth phase and monochromatic red and infrared lasers increased bacterial survival at the same fluence. Simultaneous dichromatic laser radiation induces biological effects that differ from those induced by monochromatic laser radiation and simultaneous dichromatic laser could be the option for treatment of infected pressure injuries by Pantoea agglomerans.

  3. SU-E-T-484: A New Method of Aligning Patient Setup Lasers in Radiation Therapy

    SciTech Connect

    Hwang, U; Lim, Y; Cho, K; Jeong, C; Kim, M; Jeong, J; Park, J; Shin, D; Lee, S; Kim, J; Choi, S; Kwak, J; Yoon, K; Park, S; Kim, S

    2014-06-01

    Purpose: To develop a new method to align the patient setup lasers in radiation therapy and examine its validity and effectiveness. Methods: The new laser alignment method was realized by a device composed of both a metallic base plate and few acrylic transparent plates with a cross hair line on each of them. The holders of radiochromic films were prepared in the device to find a radiation isocenter. The right laser positions could be found optically by matching the shadows of all the cross hairs in the gantry head and the device. The repeatability and reproducibility (R and R) of laser alignments and the dependency of the alignment on the position error of the light source were evaluated by comparing the standard deviations and the means of the measured laser positions. After aligning the lasers optically, a radiation isocenter was found by a collimator spoke shot and the gantry spoke shot, and then the lasers were parallely translated to the isocenter. Results: In the R and R test, the standard deviation was 1.14 mm for the new method whereas it was 1.49 mm or 2.76 mm for the conventional method with either high- or low-precision levels. In the test of the dependency on the position error of the light source, the mean laser position was shifted by 5.3 mm corresponding to the shift of the light source, 4.8 mm for the new method, but for the conventional method the laser position was shifted more than 7 times than that. The positional shift could be corrected by a parallel translation to the isocenter in the new method. Conclusion: A new laser alignment method was devised for radiation therapy and tested successfully. The method enabled us to align the lasers easily and accurately without repetition, and all lasers could be finally aligned to the radiation isocenter.

  4. The direct measurement using an imaging plate for coincidence of radiation centre and laser position in external radiation therapy.

    PubMed

    Terunuma, Toshiyuki; Sakae, Takeji; Nohtomi, Akihiro; Tsunashima, Yoshikazu

    2003-02-21

    A new method of quality assurance has been studied to measure coincidence of the radiation centre and a patient-setup laser position on a transverse plane to the beam at the isocentre. This measurement is achieved by using an imaging plate (IP). When radiation is applied to an IP, the energy is stored as trapped electrons. The number of electrons is decreased by local laser exposure. As a result, the radiation field produced by external beam irradiation is recorded as 'positive' information and the position of the patient-setup laser is recorded as 'negative' on an IP. The advantages of this method are the direct measurement, short time and high resolution. These are required for daily and monthly quality checks. We confirmed the advantage of this method by an experiment using a proton beam.

  5. Effect of laser radiation wavelength and reepithelization process on optical quality of eye cornea after laser correction of vision

    SciTech Connect

    Kitai, M S; Semchishen, A V; Semchishen, V A

    2015-10-31

    The optical quality of the eye cornea surface after performing the laser vision correction essentially depends on the characteristic roughness scale (CRS) of the ablated surface, which is mainly determined by the absorption coefficient of the cornea at the laser wavelength. Thus, in the case of using an excimer ArF laser (λ = 193 nm) the absorption coefficient is equal to 39000 cm{sup -1}, the darkening by the dissociation products takes place, and the depth of the roughness relief can be as large as 0.23 mm. Under irradiation with the Er : YAG laser (λ = 2940 nm) the clearing is observed due to the rupture of hydrogen bonds in water, and the relief depth exceeds 1 μm. It is shown that the process of reepithelization that occurs after performing the laser vision correction leads to the improvement of the optical quality of the cornea surface. (interaction of laser radiation with matter)

  6. Laser radiation action on the biomedium as nonadiabatic excitation of macromolecules

    NASA Astrophysics Data System (ADS)

    Kompanets, Igor N.; Krasnov, Andrey E.; Malov, A. N.

    1996-11-01

    The extended sphere of the laser successful use at large vagueness of the gear of radiation interaction with biological and biosimilar objects is a main modern paradox in the application of low-intensity coherent radiation in biology and medicine. There are rather regularly, for example, the reasons of immateriality of such parameters as laser radiation coherency degree for biostimulation, but the replacement of semi-conductor lasers by the light diodes isn't observed in medical practice until now. there are also no convincing results on comparative analysis of biostimulated effect under coherent and noncoherent radiation. Action of coherent electromagnetic radiation of the visible and infrared spectral range causes, as appear, the same type structure-optical changes in various objects biological liquids, cells suspensions, model biomolecular solutions, cells of plan, insects and animals. The medicobiologic consequences of laser effect are extremely variable because of the complexity of biological object and sophistication of research techniques and analyses. The energy doze of radiation acting onto a bio-object, as a rule, is extremely small, and hence like the case of extremely high frequency radiation one can to name this action by the 'informative' one, i.e., initiating only biosystem reactions is produced due to its own energy. In connection with the relatively slow biosystem response to the laser radiation action, the nonlocality of this reaction at the local action and large variety of biochemical reactions caused with laser radiation one can assume the existence of uniform physical mechanism realizing the biostimulation effect of laser radiation for various biosystems.

  7. EFFECTS OF LASER RADIATION ON MATTER: Efficient surface-erosion plasma formation in air due to the action of pulse-periodic laser radiation

    NASA Astrophysics Data System (ADS)

    Min'ko, L. Ya; Chumakou, A. N.; Bosak, N. A.

    1990-11-01

    A study was made of the interaction of a series of periodic laser (λ = 1.06 μm) pulses with a number of materials (aluminum, copper, graphite, ebonite) in air at laser radiation power densities q = 107-109 W/cm2 and repetition frequencies f<=50 kHz. The radiation was concentrated in spots of ~ 10 - 2 cm2 area. Efficient formation of plasma as a result of laser erosion (q > 2 × 108 W/cm2, f>=5 kHz) was observed. A screening layer of an air plasma created by the first pulse of the series was expelled from the interaction zone and this was followed by erosion plasma formation under conditions of slight screening of the target during the action of the subsequent laser pulses.

  8. The carbon dioxide laser: an alternative surgery technique for the treatment of common cutaneous tumors in dogs

    PubMed Central

    2014-01-01

    Background Tumors of the skin and subcutaneous tissue are the largest group of canine neoplasms. Total excision is still the most effective method for treatment of these skin tumors. For its universal properties the carbon dioxide (CO2) laser appears to be an excellent surgical instrument in veterinary surgery. Laser techniques are alternatives to traditional methods for the surgical management of tumors. The aim of this study was to compare various types of laser techniques in skin oncologic surgery: excision, ablation and mixed technique and to suggest which technique of CO2 laser procedure is the most useful in particular case of tumors in dogs. Findings The study was performed on 38 privately-owned dogs with total number of 40 skin tumors of different type removed by various CO2 laser operation techniques from 2010–2013. The treatment effect was based on the surgical wound evaluation, the relative time of healing and possible local recurrence of the tumor after 3 months post surgery. Local recurrence was observed in two cases. The study showed that in 30 cases time needed for complete resection of lesions was less than 10 minutes. Time of healing was longer than 12 days in 6 cases (42.8%) with tumor excision and in 14 cases (87.5%) where excision with ablation technique was performed. Conclusions The advantages of the CO2 laser surgery were better hemostasis, precision of working, non-contact dissection, less instruments at the site of operation and minimum traumatization of the surrounding tissues. PMID:24393628

  9. Effects of carbon dioxide (CO2) laser perforation as skin pretreatment to improve sugar infusion process of frozen blueberries.

    PubMed

    Fujimaru, Tomomi; Ling, Qingyue; Morrissey, Michael T

    2012-02-01

    Sugar infusion is a widely used osmotic treatment for fruit preservation, but the process is inherently slow and the waxy skins of some fruits hinder mass transfer during the process. This work examined the utility of perforation by a carbon dioxide (CO(2)) laser as a novel skin treatment to improve the infusion process. In 2 experiments, individually quick frozen (IQF) blueberries were subjected to varying degrees of laser perforation (3 levels of perforation density × 3 levels of perforation depth), and then infused stepwise with high fructose corn syrup (HFCS) to a final °Brix of 70 using varying solution concentration increment (5, 10, 20, and 30 °Brix/d). At each concentration, increasing perforation density and depth promoted solute migration into the fruit with increased fruit weight (P < 0.05; up to 24.15%, 37.23%, 52.89%, 65.34% wt. increase at 5, 10, 20, and 30 °Brix/d compared to the controls). Laser-treated blueberries maintained the original shape without excessive shrinkage and texture hardening due to enhanced solute incorporation, while the controls and mechanically treated samples were ruptured and wrinkled at the end of the process. Increasing solution concentrations shortened the process duration but decreased final fruit weight due to greater osmotic gradients. However, negative effects of using higher solution concentrations on final fruit weight were significantly alleviated with moderate-to-high doses of laser perforation (P < 0.001). Overall, the results demonstrate that laser perforation can be a viable skin pretreatment technique, offering marked improvement on final process yield, process efficiency, and product quality. CO(2) laser perforation as a novel skin pretreatment for sugar infusion of individually quick frozen (IQF) blueberries is presented. The technique markedly improves the product yield and quality. Although further investigation is needed, the method may potentially be used for other waxy skin fruits such as cranberries

  10. [Effects of laser radiation on the periodontium. An animal model approach. Effects of usual radiation dosage].

    PubMed

    Noguerol Rodriguez, B; Alandez Chamorro, J; Cañizares Garcia, J; Campos Muñoz, A; Sicilia Felechosa, A

    1989-05-01

    Twenty four albino mice of forty days old were selected. Twelve forty days old albino mice were irradiated with a Helium-Neon laser source, dose of 10.50566 Jul/cm2. They were divided in two groups according to time of animal sacrifice (immediately after irradiation and ten days after). As control were used twelve mice using the same time as the experimental groups, but without radiation. T.E.M. ultrathin sections showed alteration only in the conjunctiva and in the bone tissues, but not in the epithelial tissue. The bone showed two osteocyte population according to their response to irradiation. The first population showed characteristic comparable with the controls, and the second showed alterations suggestive of a degenerative process. The connective tissue also showed two fibroblasts populations, the first showed signs of a big synthesizing activity, and the second, degenerative signs. The first fibroblast population appeared in the animals sacrificed immediately after irradiation.

  11. 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.

  12. Modelling of micromachining of human tooth enamel by erbium laser radiation

    NASA Astrophysics Data System (ADS)

    Belikov, A. V.; Skrypnik, A. V.; Shatilova, K. V.

    2014-08-01

    We consider a 3D cellular model of human tooth enamel and a photomechanical cellular model of enamel ablation by erbium laser radiation, taking into account the structural peculiarities of enamel, energy distribution in the laser beam cross section and attenuation of laser energy in biological tissue. The surface area of the texture in enamel is calculated after its micromachining by erbium laser radiation. The influence of the surface area on the bond strength of enamel with dental filling materials is discussed. A good correlation between the computer simulation of the total work of adhesion and experimentally measured bond strength between the dental filling material and the tooth enamel after its micromachining by means of YAG : Er laser radiation is attained.

  13. Modification of biological objects in water media by CO{sub 2}-laser radiation

    SciTech Connect

    Baranov, G A; Belyaev, A A; Onikienko, S B; Smirnov, S A; Khukharev, V V

    2005-09-30

    The modification of biological objects (polysaccharides and cells) by CO{sub 2}-laser radiation in water added drop by drop into the interaction region is studied theoretically and experimentally. Calculations are performed by using the models describing gas-dynamic and heterogeneous processes caused by absorption of laser radiation by water drops. It is found experimentally that the laser modification of polysaccharides leads to the formation of low-molecular derivatives with immunostimulating properties. A dose of the product of laser activation of the yeast culture Saccharamyces cerevisiae prevented the development of a toxic emphysema in mice and protected them against lethal grippe and also prevented a decrease of survival rate, increased the average life, and prevented the development of metabolic and immune disorders in mice exposed to sublethal gamma-radiation doses. (laser applications and other topics in quantum electronics)

  14. The effects of pulse duration on ablation pressure driven by laser radiation

    SciTech Connect

    Zhou, Lei; Li, Xiao-Ya Zhu, Wen-Jun; Wang, Jia-Xiang; Tang, Chang-Jian

    2015-03-28

    The effects of laser pulse duration on the ablation pressure induced by laser radiation are investigated using Al target. Numerical simulation results using one dimensional radiation hydro code for laser intensities from 5×10{sup 12}W/cm{sup 2} to 5×10{sup 13}W/cm{sup 2} and pulse durations from 0.5 ns to 20 ns are presented. These results suggest that the laser intensity scaling law of ablation pressure differs for different pulse durations. And the theoretical analysis shows that the effects of laser pulse duration on ablation pressure are mainly caused by two regimes: the unsteady-state flow and the radiative energy loss to vacuum.

  15. Second-harmonic generation efficiency for multifrequency ytterbium-doped fibre laser radiation

    SciTech Connect

    Politko, M O; Kablukov, S I; Nemov, I N; Babin, Sergei A

    2013-02-28

    The second-harmonic generation (SHG) efficiency for cw Yb-doped fibre laser radiation, which is characterised by many longitudinal modes with random phases, is compared with the SHG efficiency for amplified single-frequency Nd : YAG laser radiation in ppLN and KTP crystals, characterised by the type-I and type-IIphase matching, respectively. It is shown that the conversion efficiency into the second harmonic in the multifrequency regime for both crystals is higher by a factor of about 1.6, a value close to the calculated enhancement (2 for the Gaussian mode statistics). This difference is explained by possible deviation of the statistics of the Yb-doped fibre laser radiation from Gaussian, which is confirmed by measurements of the laser temporal dynamics. (laser optics 2012)

  16. Radiation detectors based on laser sintered Bi 4Ge 3O 12 ceramics

    NASA Astrophysics Data System (ADS)

    Macedo, Zélia Soares; da Silva, Ronaldo Santos; Valerio, Mário Ernesto Giroldo; Hernandes, Antonio Carlos

    2004-06-01

    Laser sintered bismuth germanate (Bi 4Ge 3O 12) ceramics were investigated from the point of view of its potential use in radiation detector devices. The light output, density of trap centers and radiation damage were comparatively discussed for laser sintered ceramic, conventional ceramic and single crystal. The scintillator efficiency of the laser sintered ceramics was 13% higher than that observed for furnace sintered ceramics and the radiation damage levels were the same for both samples up to a dose of 3200 Gy of β radiation. The thermoluminescence results of the samples irradiated with UV and β-rays provided strong indicatives that the inter-grain defects have the same nature of the bulk defects and do not contribute with new traps in the temperature range studied. Furthermore, the density of trapping centers in the laser sintered material was 50% lower than in the conventionally sintered ceramics.

  17. Effect of laser-radiation polarization on the nonlinear scattering of light in nanodiamond suspensions

    NASA Astrophysics Data System (ADS)

    Mikheev, G. M.; Vanyukov, V. V.; Mogileva, T. N.; Puzyr', A. P.; Bondar', V. S.; Svirko, Yu. P.

    2014-07-01

    The effect of laser radiation polarization on the nonlinear scattering of light in aqueous suspensions of detonation nanodiamonds (DNDs) in a regime of optical power limiting (OPL) has been studied. It is established that the nonlinear transmission coefficient of DND suspension in the OPL regime in a field of nanosecond laser pulses with a wavelength of 532 nm is independent of the polarization of incident radiation. The nonlinear scattering of light observed at an angle of 90° in the plane perpendicular to the plane of polarization of the incident radiation depends on the polarization angle in accordance with a trigonometric law. It is shown that the ratio of the signals of scattered radiation for the vertical and horizontal polarizations exhibits nonmonotonic dependence on the laser-beam power density. The results are explained by the Rayleigh-Mie scattering and a change in the size of scattering centers as a result of the effect of a laser upon the DND suspension.

  18. Propagation of the radiation of laser instruments in road telematics systems

    NASA Astrophysics Data System (ADS)

    Palys, Marek

    2003-10-01

    In this paper I would like to present the necessity of taking into account a deformation of laser radiation in the real atmosphere while conducting measurements providing data for Intelligent Transport Systems.

  19. 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.

  20. Helicity-dependent photocurrent in the resistive Ag/Pd films excited by IR laser radiation

    SciTech Connect

    Mikheev, G M; Saushin, A S; Vanyukov, V V

    2015-07-31

    It is shown that in resistive Ag/Pd films manufactured according to the thick-film technology, in the case of oblique incidence of laser radiation of nanosecond duration at a wavelengths of 1350 – 2100 nm, a photon-drag photocurrent arises in the direction perpendicular to the plane of incidence, dependent on the ellipticity and sign of circular polarisation of incident radiation. This photocurrent consists of the so-called circular and linear contributions, which are, respectively, dependent on and independent of the sign of circular polarisation. In this wavelength range, the amplitude of the circular contribution is many times greater than that of the linear contribution. The results allow the use of resistive Ag/Pd films for the development and manufacture of innovative sensors of the sign of circular polarisation of pulsed laser radiation, operating in a wide spectral range. (interaction of laser radiation with matter. laser plasma)