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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...

  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...

  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. 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.

  9. 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.

  10. 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.

  11. 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)

  12. 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.

  13. 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

  14. 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.)

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. "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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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,...

  12. 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,...

  13. 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,...

  14. 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,...

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  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.

    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.

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  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. 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.

  15. 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.

  16. 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.

  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. 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.

  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.

    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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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)

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Biological Effects of Laser Radiation. Volume I. Review of the Literature on Biological Effects of Laser Radiation-to 1965.

    DTIC Science & Technology

    1978-10-17

    by block number) Biological Effects of Laser Radiation; Electron Spin Resonance; Spectroscopy; Microscopy: Tissue and Cell Culture Interaction...laser radiation to 1965 is reviewed. Laser production of free radicals, use in microscopy and holography, and tissue and cell culture effects are...Microscopy and Holography 16 4. Tissues and Cell Cultures 20 5. Studies on Interaction with Macromolecular Biochemical Preparations 26 6. The Laser

  1. 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).

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  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-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

  11. 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.

  12. 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.

  13. 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...

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. Change in Reflectivity of Metals under Intense Laser Radiation. Revision

    DTIC Science & Technology

    1981-05-01

    Ruby Laser Ruby Laser F. M - mirror Target L - lens F - filter or Tre Vacuum chamber attenuator Vacuum chamber W - window (a) For specular reflectance (b...of fusion the sur- face temperature remains constant. The thicIness of the molten layer de- pends on the intensity of the absorbed laser radiation and...REFLECTIVITY OF METALS UNDER INTENSE LASER RADIATION by William T. Walter A Final Technical Report DTIC t J-JUL 2 419MI A Prepared foe AIR FORCE OFFICE OF

  7. 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.

  8. 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

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  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. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. The radiation reaction effect in ultra intense laser foil interactions

    NASA Astrophysics Data System (ADS)

    Klimo, O.; Jirka, M.; Masek, M.; Limpouch, J.; Bussmann, M.; Korn, G.

    2013-05-01

    Since the radiation reaction effect on electron propagation is very small in most cases, it can be usually neglected and the Lorentz force equation can be applied. However, ultra-intense lasers with normalized vector potential of the order of 100 can accelerate electrons to relativistic velocities with very high gamma factor. When the electron is accelerated to such high velocities the amount of emitted radiation may become large and radiation damping and emission of energetic photons should be considered. This work studies the influence of the radiation reaction force on laser interaction with solid foil targets. It compares different approaches adopted in PIC simulations to take into account the radiation reaction. The simulations of a counter-propagating relativistic electron and an ultra-intense laser beam demonstrate a strong energy loss of electrons due to non-linear Compton scattering. The interaction of ultra-intense laser pulse with solid foil is studied using PIC simulations. It is shown that the effect of radiation reaction strongly depends on the recirculation of high-energy electrons. When the recirculation is efficient, the radiation coming from the target is much more intense and it shows different spectral and angular characteristics.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. [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.

  10. [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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. Quantum radiation reaction in laser-electron-beam collisions.

    PubMed

    Blackburn, T G; Ridgers, C P; Kirk, J G; Bell, A R

    2014-01-10

    It is possible using current high-intensity laser facilities to reach the quantum radiation reaction regime for energetic electrons. An experiment using a wakefield accelerator to drive GeV electrons into a counterpropagating laser pulse would demonstrate the increase in the yield of high-energy photons caused by the stochastic nature of quantum synchrotron emission: we show that a beam of 10(9) 1 GeV electrons colliding with a 30 fs laser pulse of intensity 10(22)  W cm(-2) will emit 6300 photons with energy greater than 700 MeV, 60× the number predicted by classical theory.

  4. 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.

  5. 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.

  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. 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.

  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. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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

  19. 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.

  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. 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.

  2. [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.

  3. 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.

  4. 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.

  5. 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).

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  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. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Robust signatures of quantum radiation reaction in focused ultrashort laser pulses.

    PubMed

    Li, Jian-Xing; Hatsagortsyan, Karen Z; Keitel, Christoph H

    2014-07-25

    Radiation-reaction effects in the interaction of an electron bunch with a superstrong focused ultrashort laser pulse are investigated in the quantum radiation-dominated regime. The angle-resolved Compton scattering spectra are calculated in laser pulses of variable duration using a semiclassical description for the radiation-dominated dynamics and a full quantum treatment for the emitted radiation. In dependence of the laser-pulse duration we find signatures of quantum radiation reaction in the radiation spectra, which are characteristic for the focused laser beam and visible in the qualitative behavior of both the angular spread and the spectral bandwidth of the radiation spectra. The signatures are robust with respect to the variation of the electron and laser-beam parameters in a large range. Qualitatively, they differ fully from those in the classical radiation-reaction regime and are measurable with presently available laser technology.

  14. 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.

  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. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. [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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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)

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Stimulated Raman backscattering of laser radiation in deep plasma channels

    NASA Astrophysics Data System (ADS)

    Kalmykov, S. Yu.; Shvets, G.

    2004-10-01

    Stimulated Raman backscattering (RBS) of intense laser radiation confined by a single-mode plasma channel with a radial variation of plasma frequency greater than a homogeneous-plasma RBS bandwidth is characterized by a strong transverse localization of resonantly driven electron plasma waves (EPW). The EPW localization reduces the peak growth rate of RBS and increases the amplification bandwidth. The continuum of nonbound modes of backscattered radiation shrinks the transverse field profile in a channel and increases the RBS growth rate. Solution of the initial-value problem shows that an electromagnetic pulse amplified by the RBS in the single-mode deep plasma channel has a group velocity higher than in the case of homogeneous-plasma Raman amplification. Implications to the design of a RBS pulse compressor in a plasma channel are discussed.

  12. 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.

  13. 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.

  14. 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

  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. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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)

  11. 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)

  12. 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.

  13. 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'.

  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. 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.

  16. 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)

  17. 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.

  18. 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.

  19. 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)

  20. 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.

  1. 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.

  2. 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.

  3. 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'.

  4. 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).

  5. 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.

  6. 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.

  7. Radiation reaction effects on the interaction of an electron with an intense laser pulse.

    PubMed

    Kravets, Yevgen; Noble, Adam; Jaroszynski, Dino

    2013-07-01

    Radiation reaction effects will play an important role in near-future laser facilities, yet their theoretical description remains obscure. We explore the Ford-O'Connell equation for radiation reaction, and discuss its relation to other commonly used treatments. By analyzing the interaction of a high energy electron in an intense laser pulse, we find that radiation reaction effects prevent the particle from accessing a regime in which the Landau-Lifshitz approximation breaks down.

  8. 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.

  9. 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.

  10. 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.

  11. Propagation of High-Power, Femtosecond Laser Radiation through the Atmosphere

    DTIC Science & Technology

    2004-10-19

    achieved recently in development of new laser technologies stimulates their active use in optics of natural media. Unique properties of laser radiation...allow new information on the objects under study to be obtained. A prominent example is the application of femtosecond lasers to atmospheric sensing...sensing of ecologically dangerous gaseous and aerosol substances. For efficient application of high-power lasers in the environmental research, it is

  12. 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)

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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)

  1. 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.

  2. 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)

  3. 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.

  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. 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)

  6. 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

  7. 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.

  8. 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

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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).

  17. 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.

  18. 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)

  19. 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.

  20. 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.

  1. 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.

  2. [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.

  3. 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.

  4. 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.

  5. 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)

  6. 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.

  7. 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)

  8. INTERACTION OF LASER RADIATION WITH MATTER: IR multiphoton dissociation of trichlorosilane induced by pulsed CO2 and NH3 laser radiation

    NASA Astrophysics Data System (ADS)

    Apatin, V. M.; Laptev, Vladimir B.; Ryabov, Evgenii A.

    2003-10-01

    The IR multiphoton dissociation of trichlorosilane (SiHCl3) molecules irradiated by pulses from CO2 and NH3 lasers is studied. The dependences of dissociation yield on the frequency and energy density of laser radiation, as well as on the parent pressure of SiHCl3, are determined. It is found that HCl and a solid precipitate, probably with a common chemical formula (SiCl2)n, are the main products of dissociation of trichlorosilane.

  9. 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.

  10. 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.

  11. 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.

  12. Photoblepharokeratoconjunctivitis caused by invisible infrared radiation emitted from a green laser pointer.

    PubMed

    Khedr, Yahya A H; Khedr, Abdulla H

    2014-03-11

    There are a wide variety of laser pointers sold to the general public. Among those are the high-powered diode-pumped solid-state lasers (>5 mW), which do not follow the laser safety regulations for packing, and are sold as regular lasers without the infrared (IR) filters. In this case report, we encountered a patient with photoblepharokeratoconjunctivitis caused by the invisible IR radiations emitted from a green laser pointer. Owing to the thermal effect of the invisible IR rays led to the disease.

  13. Electron momentum spectroscopy of H+ 2 in the presence of laser radiation*

    NASA Astrophysics Data System (ADS)

    Bulychev, Andrew A.; Kouzakov, Konstantin A.

    2017-02-01

    Theoretical analysis of laser-assisted electron impact ionization of a hydrogen molecular ion H+ 2 at high impact energy and large momentum transfer is carried out. The laser-field effects on the incoming and outgoing electrons are taken into account using the Volkov functions. The field-dressing of the target electron is treated with a quasistatic state approach. Calculations for laser radiation with frequency ω = 1.55 eV and intensity I = 5 × 1011 W/cm2 exhibit strong laser influence on the molecular bond oscillation in laser-assisted electron momentum distributions.

  14. INTERACTION OF LASER RADIATION WITH MATTER: Influence of a target on operation of a pulsed CO2 laser emitting microsecond pulses

    NASA Astrophysics Data System (ADS)

    Baranov, V. Yu; Dolgov, V. A.; Malyuta, D. D.; Mezhevov, V. S.; Semak, V. V.

    1987-12-01

    The profile of pulses emitted by a TEA CO2 laser with an unstable resonator changed as a result of interaction of laser radiation with the surface of a metal in the presence of a breakdown plasma. This influence of a target on laser operation and its possible applications in laser processing of materials are analyzed.

  15. Low-output carbon dioxide laser for cutaneous wound closure of scalpel incisions: comparative tensile strength studies of the laser to the suture and staple for wound closure

    SciTech Connect

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

    1986-01-01

    The low-output carbon dioxide (CO/sub 2/) laser was used for cutaneous wound closure of scalpel incisions. Cutaneous scalpel incisions were placed over the dorsum of three minipigs and were then closed by either the laser, sutures, or staples. At multiple time points after wound closure, up to day 90, the tensile strengths of these wounds were comparatively evaluated. All wounds, including those closed with the laser, clinically appeared to heal similarly with no evidence of wound dehiscence or infection. Tensile strength studies revealed similar sigmoid curves for all wound closure modalities with low initial tensile strengths up to days 14 to 21, which afterwards increased rapidly, with a plateau toward day 90. From our study, it appears that the CO/sub 2/ laser, in the low-output mode, can be used for cutaneous wound closure and that similar clinical healing and tensile strength measurements are obtained relative to the conventional cutaneous wound closure modalities of the suture or staple.

  16. SCATTERING AND REFLECTION OF LASER RADIATION: Multiple dynamic scettering of laser radiation on a light-induced jet of microparticles in suspension

    NASA Astrophysics Data System (ADS)

    Skipetrov, S. E.; Chesnokov, S. S.; Zakharov, S. D.; Kazaryan, M. A.; Korotkov, N. P.; Shcheglov, V. A.

    1998-05-01

    A self-consistent theoretical analysis is made of the multiple scattering of coherent laser radiation in a random medium under conditions of formation of a light-induced jet of scatterers. It is shown, that the laser particle acceleration leads to a qualitative change of the temporal auto-correlation function of scattered light as compared to the case of scattering on chaotically moving Brownian particles. The effect of radiation absorption on the temporal coherence of the multiple-scattered light under conditions of light-induced particle motion in the scattering medium is studied.

  17. The impact of myoglobin on the efficiency of the therapeutic effect of low intensity laser radiation

    NASA Astrophysics Data System (ADS)

    Asimov, M. M.; Asimov, R. M.; Gisbrecht, A.

    2013-03-01

    We present the results from numerical simulation of the interaction of laser optical radiation with myoglobin (Mb) and oxymyoglobin (MbO2) in muscle tissue. It is shown that the photodissociation of MbO2 can modify the concentration of oxygen (O2) in the muscle tissue directly at the irradiation zone. The criteria of the effectiveness of the combined effect of biological tissue oxygenation by two-wavelength laser radiation are considered.

  18. Evolution analysis of EUV radiation from laser-produced tin plasmas based on a radiation hydrodynamics model

    NASA Astrophysics Data System (ADS)

    Su, M. G.; Min, Q.; Cao, S. Q.; Sun, D. X.; Hayden, P.; O’Sullivan, G.; Dong, C. Z.

    2017-03-01

    One of fundamental aims of extreme ultraviolet (EUV) lithography is to maximize brightness or conversion efficiency of laser energy to radiation at specific wavelengths from laser produced plasmas (LPPs) of specific elements for matching to available multilayer optical systems. Tin LPPs have been chosen for operation at a wavelength of 13.5 nm. For an investigation of EUV radiation of laser-produced tin plasmas, it is crucial to study the related atomic processes and their evolution so as to reliably predict the optimum plasma and experimental conditions. Here, we present a simplified radiation hydrodynamic model based on the fluid dynamic equations and the radiative transfer equation to rapidly investigate the evolution of radiation properties and dynamics in laser-produced tin plasmas. The self-absorption features of EUV spectra measured at an angle of 45° to the direction of plasma expansion have been successfully simulated and explained, and the evolution of some parameters, such as the plasma temperature, ion distribution and density, expansion size and velocity, have also been evaluated. Our results should be useful for further understanding of current research on extreme ultraviolet and soft X-ray source development for applications such as lithography, metrology and biological imaging.

  19. Evolution analysis of EUV radiation from laser-produced tin plasmas based on a radiation hydrodynamics model

    PubMed Central

    Su, M. G.; Min, Q.; Cao, S. Q.; Sun, D. X.; Hayden, P.; O’Sullivan, G.; Dong, C. Z.

    2017-01-01

    One of fundamental aims of extreme ultraviolet (EUV) lithography is to maximize brightness or conversion efficiency of laser energy to radiation at specific wavelengths from laser produced plasmas (LPPs) of specific elements for matching to available multilayer optical systems. Tin LPPs have been chosen for operation at a wavelength of 13.5 nm. For an investigation of EUV radiation of laser-produced tin plasmas, it is crucial to study the related atomic processes and their evolution so as to reliably predict the optimum plasma and experimental conditions. Here, we present a simplified radiation hydrodynamic model based on the fluid dynamic equations and the radiative transfer equation to rapidly investigate the evolution of radiation properties and dynamics in laser-produced tin plasmas. The self-absorption features of EUV spectra measured at an angle of 45° to the direction of plasma expansion have been successfully simulated and explained, and the evolution of some parameters, such as the plasma temperature, ion distribution and density, expansion size and velocity, have also been evaluated. Our results should be useful for further understanding of current research on extreme ultraviolet and soft X-ray source development for applications such as lithography, metrology and biological imaging. PMID:28332621

  20. Evolution analysis of EUV radiation from laser-produced tin plasmas based on a radiation hydrodynamics model.

    PubMed

    Su, M G; Min, Q; Cao, S Q; Sun, D X; Hayden, P; O'Sullivan, G; Dong, C Z

    2017-03-23

    One of fundamental aims of extreme ultraviolet (EUV) lithography is to maximize brightness or conversion efficiency of laser energy to radiation at specific wavelengths from laser produced plasmas (LPPs) of specific elements for matching to available multilayer optical systems. Tin LPPs have been chosen for operation at a wavelength of 13.5 nm. For an investigation of EUV radiation of laser-produced tin plasmas, it is crucial to study the related atomic processes and their evolution so as to reliably predict the optimum plasma and experimental conditions. Here, we present a simplified radiation hydrodynamic model based on the fluid dynamic equations and the radiative transfer equation to rapidly investigate the evolution of radiation properties and dynamics in laser-produced tin plasmas. The self-absorption features of EUV spectra measured at an angle of 45° to the direction of plasma expansion have been successfully simulated and explained, and the evolution of some parameters, such as the plasma temperature, ion distribution and density, expansion size and velocity, have also been evaluated. Our results should be useful for further understanding of current research on extreme ultraviolet and soft X-ray source development for applications such as lithography, metrology and biological imaging.

  1. Study on the electromagnetic radiation characteristics of discharging excimer laser system

    NASA Astrophysics Data System (ADS)

    Zhao, Duliang; Liang, Xu; Fang, Xiaodong; Wang, Qingsheng

    2016-10-01

    Excimer laser in condition of high voltage, large current and fast discharge will produce strong electromagnetic pulse radiation and electromagnetic interference on the around electrical equipment. The research on characteristics and distribution of excimer laser electromagnetic radiation could provide important basis for electromagnetic shielding and suppressing electromagnetic interference, and further improving the electromagnetic compatibility of system. Firstly, electromagnetic radiation source is analyzed according to the working principle of excimer laser. The key test points of the electromagnetic radiation, hydrogen thyratron, main discharge circuit and laser outlet, are determined by the mechanical structure and the theory of electromagnetic radiation. Secondly, characteristics of electromagnetic field were tested using a near field probe on the key positions of the vertical direction at 20, 50, and 80 cm, respectively. The main radiation frequencies and the radiation field characteristics in the near field are obtained. The experimental results show that the main radiation frequencies distribute in 47, 65, and 130 MHz for electric field and the main radiation frequencies distribute in 34, 100, and 165 MHz for magnetic field. The intensity of electromagnetic field decreases rapidly with the increase of test distance. The higher the frequency increases, the faster the amplitude attenuate. Finally, several electromagnetic interference suppression measurement methods are proposed from the perspective of electromagnetic compatibility according to the test results.

  2. On the Observation of Jitter Radiation in Solid-Density Laser-Plasma Laboratory Experiments

    NASA Astrophysics Data System (ADS)

    Keenan, Brett; Medvedev, Mikhail

    2015-11-01

    Plasmas created by high-intensity lasers are often subject to the formation of kinetic-streaming instabilities, such as the Weibel instability, which lead to the spontaneous generation of high-amplitude, tangled magnetic fields. These fields typically exist on small spatial scales, i.e., ``sub-Larmor scales''. Radiation from charged particles moving through small-scale electromagnetic (EM) turbulence, known as jitter radiation, has spectral characteristics distinct from both synchrotron and cyclotron radiation, and it carries valuable information on the statistical properties of the EM field structure and evolution. Consequently, jitter radiation from laser-produced plasmas may offer insight into the underlying electromagnetic turbulence. Here we investigate the prospects for, and demonstrate the feasibility of, such direct radiative diagnostics for mildly relativistic, solid-density laser plasmas produced in lab experiments. Supported by grant DOE grant DE-FG02-07ER54940 and NSF grant AST-1209665.

  3. Mitigation of Laser Damage Growth in Fused Silica NIF Optics with a Galvanometer Scanned Carbon Dioxide Laser

    SciTech Connect

    Bass, I L; Draggoo, V; Guss, G M; Hackel, R P; Norton, M A

    2006-04-06

    Economic operation of the National Ignition Facility at the Lawrence Livermore National Laboratory depends on controlling growth of laser damage in the large, high cost optics exposed to UV light at 351 nm. Mitigation of the growth of damage sites on fused silica surfaces greater than several hundred microns in diameter has been previously reported by us using galvanometer scanning of a tightly focused 10.6 {micro}m CO{sub 2} laser spot over an area encompassing the laser damage. Further investigation revealed that fused silica vapor re-deposited on the surface as ''debris'' led to laser damage at unexpectedly low fluences when exposed to multiple laser shots at 351 nm. Additionally, laser power and spatial mode fluctuations in the mitigation laser led to poor repeatability of the process. We also found that the shape of the mitigation pit could produce downstream intensification that could damage other NIF optics. Modifications were made to both the laser system and the mitigation process in order to address these issues. Debris was completely eliminated by these changes, but repeatability and downstream intensification issues still persist.

  4. CONTROL OF LASER RADIATION PARAMETERS: Transformation of the spatial coherence of pulsed laser radiation transmitted in the nonlinear regime through a multimode graded-index fibre

    NASA Astrophysics Data System (ADS)

    Kitsak, A. I.; Kitsak, M. A.

    2006-01-01

    A method is proposed for transformation of the spatial coherence of pulsed laser radiation upon nonlinear interaction in a multimode fibre. The specific features of the transmission of correlation properties of radiation in a graded-index fibre with regular and irregular profiles of the refractive index of the fibre core are analysed. A comparative analysis of the parameter of global degree of radiation coherence at the output of inhomogeneous waveguide and non-waveguide media is performed. It is shown that the most efficient mechanism of decorrelation of pulsed radiation in an optical fibre is fluctuations of the phase of radiation scattered by inhomogeneities of the refractive index of the fibre core induced due to nonlinear interaction with radiation with the spatially inhomogeneous intensity distribution.

  5. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA Generation of an electric signal in the interaction of HF-laser radiation with bottom surface of a water column

    NASA Astrophysics Data System (ADS)

    Andreev, Stepan N.; Kazantsev, S. Yu; Kononov, I. G.; Pashinin, Pavel P.; Firsov, K. N.

    2010-10-01

    Generation of an electrical signal (ES) is experimentally investigated in the interaction of the pulse of a non-chain electric-discharge HF laser with the bottom surface of a water column. It was found that the ES amplitude is influenced by thin water layers (water contacts) present in the system under study, which undergo mechanical action in the process of water column movement initiated by the laser. Approximately ten-fold increase in the ES amplitude is observed if the water layer is present in the gap between the end of the water cell and surface of the quartz plate covering the cell and having a contact with the top water column boundary, as compared to the case of the free top boundary. Possible reasons for the thin water layer influence on ES characteristics and for the mechanism for the second ES peak origin in collapsing of the vapour cavity produced during water volume explosive boiling under the laser radiation are qualitatively discussed.

  6. Effect of a laser irradiation on the vascularisation of safety and X-ray radiated bone.

    PubMed

    Desmons, Sophie; Delfosse, Caroline; Rochon, Philippe; Buys, Bruno; Penel, Guillaume; Mordon, Serge

    2007-01-01

    Thermal preconditioning induces a cytoprotective effect and promotes tissue recovering. Laser is an appropriated method to generate a controlled and reproducible heating. Bone healing, a crucial challenge in medicine, is affected by X-ray radiation which induces a chronic antiangiogenic effect. So, this study aims to investigate the role of laser preconditioning on the vascularisation of bone after X-ray radiation. An optical bone chamber allowed the study of the vascularization process. The vascular density (VD) was determined using image processing. A longitudinal study was performed on 20 rabbits divided in four groups: #1: control group (n=5); #2: laser irradiation alone (diode laser 810nm, fluence= 48J/cm2) (n=5). #3: X-ray radiation (18.75Gy) alone (n=5), #4: laser preconditioning 24 hours before a X-ray radiation (n=5). VD remained stable during 12-week follow up for groups #1 and #2. X-ray radiation lead to an important decrease of the superficial bone vascularization in group #3. The decrease of the vascularization was limited in group #4 highlighting a different evolution between group #3 and #4. Those results were confirmed by histological analysis. Our preliminary findings show that laser preconditioning preserves vascularization in X-ray radiated bone site, outlining a novel approach for the bone healing in which the vascular supply has been injured.

  7. Development of Extreme Ultraviolet Radiation Source using Laser Triggered Vacuum Spark Discharge Plasma

    SciTech Connect

    Watanabe, Masato; Yamada, Junzaburo; Zhu Qiushi; Hotta, Eiki

    2009-01-21

    A laser triggerd discharge produced Sn plasma light source has been developed. Experimental parameters such as electrode separation and laser irradiation power are varied to optimize EUV emission power. It is clear that the maximum EUV radiation was occurred in the position where the pinch was observed.

  8. Compton backscattering of intracavity storage ring free-electron laser radiation

    SciTech Connect

    Dattoli, G.; Giannessi, L.; Torre, A.

    1995-12-31

    We discuss the{gamma}-ray production by Compton backscattering of intracavity storage ring Free-Electron Laser radiation. We use a semi-analytical model which provides the build up of the signal combined with the storage ring damping mechanism and derive simple relations yielding the connection between backscattered. Photons brightness and the intercavity laser equilibrium intensity.

  9. Designing a Broadband Pump for High-Quality Micro-Lasers via Modified Net Radiation Method

    NASA Astrophysics Data System (ADS)

    Nechayev, Sergey; Reusswig, Philip D.; Baldo, Marc A.; Rotschild, Carmel

    2016-12-01

    High-quality micro-lasers are key ingredients in non-linear optics, communication, sensing and low-threshold solar-pumped lasers. However, such micro-lasers exhibit negligible absorption of free-space broadband pump light. Recently, this limitation was lifted by cascade energy transfer, in which the absorption and quality factor are modulated with wavelength, enabling non-resonant pumping of high-quality micro-lasers and solar-pumped laser to operate at record low solar concentration. Here, we present a generic theoretical framework for modeling the absorption, emission and energy transfer of incoherent radiation between cascade sensitizer and laser gain media. Our model is based on linear equations of the modified net radiation method and is therefore robust, fast converging and has low complexity. We apply this formalism to compute the optimal parameters of low-threshold solar-pumped lasers. It is revealed that the interplay between the absorption and self-absorption of such lasers defines the optimal pump absorption below the maximal value, which is in contrast to conventional lasers for which full pump absorption is desired. Numerical results are compared to experimental data on a sensitized Nd3+:YAG cavity, and quantitative agreement with theoretical models is found. Our work modularizes the gain and sensitizing components and paves the way for the optimal design of broadband-pumped high-quality micro-lasers and efficient solar-pumped lasers.

  10. Designing a Broadband Pump for High-Quality Micro-Lasers via Modified Net Radiation Method.

    PubMed

    Nechayev, Sergey; Reusswig, Philip D; Baldo, Marc A; Rotschild, Carmel

    2016-12-07

    High-quality micro-lasers are key ingredients in non-linear optics, communication, sensing and low-threshold solar-pumped lasers. However, such micro-lasers exhibit negligible absorption of free-space broadband pump light. Recently, this limitation was lifted by cascade energy transfer, in which the absorption and quality factor are modulated with wavelength, enabling non-resonant pumping of high-quality micro-lasers and solar-pumped laser to operate at record low solar concentration. Here, we present a generic theoretical framework for modeling the absorption, emission and energy transfer of incoherent radiation between cascade sensitizer and laser gain media. Our model is based on linear equations of the modified net radiation method and is therefore robust, fast converging and has low complexity. We apply this formalism to compute the optimal parameters of low-threshold solar-pumped lasers. It is revealed that the interplay between the absorption and self-absorption of such lasers defines the optimal pump absorption below the maximal value, which is in contrast to conventional lasers for which full pump absorption is desired. Numerical results are compared to experimental data on a sensitized Nd(3+):YAG cavity, and quantitative agreement with theoretical models is found. Our work modularizes the gain and sensitizing components and paves the way for the optimal design of broadband-pumped high-quality micro-lasers and efficient solar-pumped lasers.

  11. Designing a Broadband Pump for High-Quality Micro-Lasers via Modified Net Radiation Method

    PubMed Central

    Nechayev, Sergey; Reusswig, Philip D.; Baldo, Marc A.; Rotschild, Carmel

    2016-01-01

    High-quality micro-lasers are key ingredients in non-linear optics, communication, sensing and low-threshold solar-pumped lasers. However, such micro-lasers exhibit negligible absorption of free-space broadband pump light. Recently, this limitation was lifted by cascade energy transfer, in which the absorption and quality factor are modulated with wavelength, enabling non-resonant pumping of high-quality micro-lasers and solar-pumped laser to operate at record low solar concentration. Here, we present a generic theoretical framework for modeling the absorption, emission and energy transfer of incoherent radiation between cascade sensitizer and laser gain media. Our model is based on linear equations of the modified net radiation method and is therefore robust, fast converging and has low complexity. We apply this formalism to compute the optimal parameters of low-threshold solar-pumped lasers. It is revealed that the interplay between the absorption and self-absorption of such lasers defines the optimal pump absorption below the maximal value, which is in contrast to conventional lasers for which full pump absorption is desired. Numerical results are compared to experimental data on a sensitized Nd3+:YAG cavity, and quantitative agreement with theoretical models is found. Our work modularizes the gain and sensitizing components and paves the way for the optimal design of broadband-pumped high-quality micro-lasers and efficient solar-pumped lasers. PMID:27924844

  12. On a semiconductor laser with a p–n tunnel junction with radiation emission through the substrate

    SciTech Connect

    Kolpakov, D. A. Zvonkov, B. N.; Nekorkin, S. M.; Dikareva, N. V.; Aleshkin, V. Ya.; Dubinov, A. A.

    2015-11-15

    A multiwell interband cascade laser with a tunnel junction within a single waveguide and radiation emission through the substrate is implemented for the first time. It is shown that such a laser heterostructure design provides the more efficient population of quantum wells in comparison with a conventional multiwell laser with radiation emission through the substrate, due to which the lasing threshold is significantly lowered.

  13. LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Spectral characteristics of fragmentation of kidney stones by microsecond laser radiation

    NASA Astrophysics Data System (ADS)

    Batishche, S. A.; Tarkovsky, V. V.

    1995-07-01

    A study of the action of single microsecond laser pulses on kidney stones revealed a strong spectral dependence of the efficiency K of mass removal. This should be taken into account in the development of apparatus for laser lithotripsy. An increase in the energy of the laser pulses acting on a stone resulted in saturation of K when a certain energy, specific to each wavelength, was exceeded. The radiation energy should be less than the saturation threshold in order to reduce the effects on the surrounding tissues.

  14. Comparison of vasovasostomy techniques in rats utilizing conventional microsurgical suture, carbon dioxide laser, and fibrin tissue adhesives.

    PubMed

    Ball, R A; Steinberg, J; Wilson, L A; Loughlin, K R

    1993-05-01

    An evaluation of vas reanastomoses in rats comparing suture only, carbon dioxide (CO2) laser-assisted, and fibrin-based tissue adhesive was performed in our laboratory. A cohort of 60 known fertile male Sprague Dawley rats initially underwent lower midline abdominal exploration and transection of their vas deferens bilaterally, followed by immediate microsurgical vasovasostomy by one of the three experimental methods. All groups initially had the severed vasa ends coapted by two or three transmural (mucosa through serosa) sutures of 10-0 nylon under an operating microscope. The conventionally sutured group had an additional four to six nylon 10-0 sutures placed externally in the serosa only to complete the anastomosis. The CO2 laser-assisted group underwent laser welding with denaturation of the serosa to seal the anastomosis. A fibrin-based tissue adhesive, produced by combining human cryoprecipitate and thrombin, was placed topically over the coapted vas ends to seal the anastomosis in the third group. Postoperative evaluation revealed similarities among the three surgical groups with the fibrin-based tissue adhesive group resulting in the highest patency rate (89%) and pregnancy rate (85%) as well as the lowest granulation rate (18%) and shortest operative time (27 minutes). The laser-assisted group resulted in the lowest pregnancy rate (68%), while the sewn anastomosis group had the lowest patency rate (76%). Both laser-assisted and conventionally sewn vasectomy reversals required significantly longer operative time (39 and 46 minutes, respectively) compared with the fibrin-based tissue adhesive-assisted procedures (p < 0.01). This study provides evidence that alternative microsurgical techniques may be utilized to perform uncomplicated, expeditious, and successful vasectomy reversals.

  15. CONTROL OF LASER RADIATION PARAMETERS: Computational and experimental study of a Q-switched cw chemical HF/DF laser

    NASA Astrophysics Data System (ADS)

    Aleksandrov, Boris S.; Kuprenyuk, V. I.; Maksimov, Yurii P.; Mashendzhinov, Viktor I.; Rodionov, A. Yu; Rotinyan, Mikhail A.; Sudarikov, V. V.; Tret'yakov, Nikolai E.; Fedorov, Igor'A.; Etsina, Alla L.

    2007-06-01

    The energy and temporal parameters of radiation from a cw chemical medium-size HF/DF laser mechanically Q-switched by a mirror rotating at a frequency of up to 1 kHz are calculated and studied experimentally. The peak power of laser pulses in the repetitively pulsed regime exceeds the cw output power of the HF laser at least by a factor of four. The average power in the repetitively pulses regime is lower than that in the cw regime, but it increases (approximately doubles) with increasing modulation frequency. The time of the complete recovery of the gain profile in the active medium is measured to be 6-7 μs. Two numerical models are developed which describe the dynamics of Q-switched HF and DF lasers. Some specific features of the operation of these lasers are analysed with the help of these models.

  16. Low-intensity infrared laser radiation influence on the tumor growth

    NASA Astrophysics Data System (ADS)

    Cheida, A. A.; Efimova, E. G.

    2005-08-01

    Infrared laser radiation of low intensity in exposition dose of 25-35 mJicm2 does not cause progress the tumor process. Moreover, disturbing the blood flow in the tumor due to changing synthesis of norepinephrine and histamine this radiation contributes to the damage of the tumor tissue accompanied by the beginning of adaptation reaction in the organism.

  17. Generation of terahertz radiation by focusing femtosecond bichromatic laser pulses in a gas or plasma

    SciTech Connect

    Chizhov, P A; Volkov, Roman V; Bukin, V V; Ushakov, A A; Garnov, Sergei V; Savel'ev-Trofimov, Andrei B

    2013-04-30

    The generation of terahertz radiation by focusing two-frequency femtosecond laser pulses is studied. Focusing is carried out both in an undisturbed gas and in a pre-formed plasma. The energy of the terahertz radiation pulses is shown to reduce significantly in the case of focusing in a plasma. (extreme light fields and their applications)

  18. Quantum fluctuations of radiation in a ring Nd : YAG chip laser

    SciTech Connect

    Lariontsev, E G; Firsov, V V

    2015-07-31

    We report theoretical and experimental investigation of intensity fluctuations in a travelling-wave ring Nd : YAG chip laser, caused by the noise of spontaneous emission. In accordance with theory and experiment, quantum intensity fluctuations in the laser under study decrease dramatically with increasing pump over the threshold. As a result of the research performed, the factor β is found, which determines the ratio of the rate of spontaneous emission into the generated mode to the total rate of spontaneous emission into all modes. The effect of the relaxation rate from the lower laser level on quantum fluctuations of the radiation intensity is found. (control of radiation parameters)

  19. Dependence of injection locking of a TEA CO2 laser on intensity of injected radiation

    NASA Technical Reports Server (NTRS)

    Oppenheim, U. P.; Menzies, R. T.; Kavaya, M. J.

    1982-01-01

    The results of an experimental study to determine the minimum required injected power to control the output frequency of a TEA CO2 laser are reported. A CW CO2 waveguide laser was used as the injection oscillator. Both the power and the frequency of the injected radiation were varied, while the TEA resonator cavity length was adjusted to match the frequency of the injected signal. Single-longitudinal mode (SLM) TEA laser radiation was produced for injected power levels which are several orders of magnitude below those previously reported. The ratio of SLM output power to injection power exceeded 10 to the 12th at the lowest levels of injected intensity.

  20. Radiation build-up in laminar and turbulent regimes in quasi-CW Raman fiber laser.

    PubMed

    Smirnov, Sergey V; Tarasov, Nikita; Churkin, Dmitry V

    2015-10-19

    We study the radiation build-up in laminar and turbulent generation regimes in quasi-CW Raman fiber laser. We found the resulted spectral shape and generation type is defined by the total spectral broadening/narrowing balance over laser cavity round-trip, which is substantially different in different regimes starting from first round-trips of the radiation build-up. In turbulent regime, the steady-state is reached only after a few round-trips, while in the laminar regime the laser approaches the equilibrium spectrum shape asymptotically.

  1. Strong Field-Induced Frequency Conversion of Laser Radiation in Plasma Plumes: Recent Achievements

    PubMed Central

    Ganeev, R. A.

    2013-01-01

    New findings in plasma harmonics studies using strong laser fields are reviewed. We discuss recent achievements in the growth of the efficiency of coherent extreme ultraviolet (XUV) radiation sources based on frequency conversion of the ultrashort pulses in the laser-produced plasmas, which allowed for the spectral and structural studies of matter through the high-order harmonic generation (HHG) spectroscopy. These studies showed that plasma HHG can open new opportunities in many unexpected areas of laser-matter interaction. Besides being considered as an alternative method for generation of coherent XUV radiation, it can be used as a powerful tool for various spectroscopic and analytical applications. PMID:23864818

  2. Study of the effect of properties of material on vacuum breakdown initiated by laser radiation

    SciTech Connect

    Seleznev, V. P.; Revazov, V. O.

    2015-12-15

    In this work, the effect of various properties of materials on vacuum breakdown initiated by laser radiation is considered. Estimating calculations are performed which show that the material of the target electrode distinctly affects the minimum energy of laser radiation needed for igniting a vacuum spark. The experimental studies carried out confirm the estimating calculations, and a number of materials are revealed which can be arranged in order of increase in the energy needed for the formation of breakdown in vacuum by the impact of a laser pulse.

  3. Revisiting the interplay between ablation, collisional, and radiative processes during ns-laser ablation

    NASA Astrophysics Data System (ADS)

    Autrique, D.; Gornushkin, I.; Alexiades, V.; Chen, Z.; Bogaerts, A.; Rethfeld, B.

    2013-10-01

    A study of ns-laser ablation is presented, which focuses on the transient behavior of the physical processes that act in and above a copper sample. A dimensionless multiphase collisional radiative model describes the interplay between the ablation, collisional, and radiative mechanisms. Calculations are done for a 6 ns-Nd:YAG laser pulse operating at 532 nm and fluences up to 15 J/cm2. Temporal intensity profiles as well as transmissivities are in good agreement with experimental results. It is found that volumetric ablation mechanisms and photo-processes both play an essential role in the onset of ns-laser induced breakdown.

  4. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Limitation of high-power optical radiation by organic molecules: I. Substituted pyranes and cyanine dyes

    NASA Astrophysics Data System (ADS)

    Kopylova, T. N.; Svetlichnyi, Valerii A.; Mayer, G. V.; Reznichenko, A. V.; Podgaetskii, Vitalii M.; Ponomareva, O. V.; Samsonova, L. G.; Filinov, D. N.; Pomogaev, V. A.; Tel'minov, E. N.; Lapin, I. N.; Svetlichnaya, N. N.; Sinchenko, E. I.

    2003-11-01

    Photophysical processes proceeding in polyatomic organic molecules (pyran derivatives and cyanines) excited by high-power laser radiation at 532 nm are studied. Some properties of their changes depending on the structure, solvent, and excitation conditions are determined. The effect of limitation of high-power exciting radiation by the organic molecules is found. The maximum limitation (Kmax = 15.0 at the initial transmission equal to 70%) was observed for the cyanine derivative and is comparable to this effect for fullerenes C60, which are widely used as radiation limiters.

  5. Design and experimental study of a secondary hohlraum radiation source with laser focal spots blocked

    SciTech Connect

    Song, Tianming Zhu, Tuo; Yang, Jiamin; Huang, Chengwu; Wang, Feng; Peng, Xiaoshi; Xu, Tao; Li, Zhichao; Zhang, Huan

    2016-01-15

    A design of secondary hohlraum radiation source with laser focal spots blocked is introduced. The hard x-ray radiation such as the gold M-band emission and hot electrons from the coronal plasma were designed to be shielded using a cylindrical shield. Three-dimensional view factor analysis was carried out to optimize the shield structure to achieve higher radiation temperature. An experiment was performed at Shenguang III prototype laser facility to verify the design. Velocity Interferometer System for Any Reflector was used to measure the shock wave speed in a three-stepped Al sample driven by this radiation source and the peak radiation temperature of the radiation source was estimated to be about 90 eV.

  6. Design and experimental study of a secondary hohlraum radiation source with laser focal spots blocked

    NASA Astrophysics Data System (ADS)

    Song, Tianming; Zhu, Tuo; Yang, Jiamin; Huang, Chengwu; Wang, Feng; Peng, Xiaoshi; Xu, Tao; Li, Zhichao; Zhang, Huan

    2016-01-01

    A design of secondary hohlraum radiation source with laser focal spots blocked is introduced. The hard x-ray radiation such as the gold M-band emission and hot electrons from the coronal plasma were designed to be shielded using a cylindrical shield. Three-dimensional view factor analysis was carried out to optimize the shield structure to achieve higher radiation temperature. An experiment was performed at Shenguang III prototype laser facility to verify the design. Velocity Interferometer System for Any Reflector was used to measure the shock wave speed in a three-stepped Al sample driven by this radiation source and the peak radiation temperature of the radiation source was estimated to be about 90 eV.

  7. Observation of fine structures in laser-driven electron beams using coherent transition radiation.

    PubMed

    Glinec, Y; Faure, J; Norlin, A; Pukhov, A; Malka, V

    2007-05-11

    We have measured the coherent optical transition radiation emitted by an electron beam from laser-plasma interaction. The measurement of the spectrum of the radiation reveals fine structures of the electron beam in the range 400-1000 nm. These structures are reproduced using an electron distribution from a 3D particle-in-cell simulation and are attributed to microbunching of the electron bunch due to its interaction with the laser field. When the radiator is placed closer to the interaction point, spectral oscillations have also been recorded, signature of the interference of the radiation produced by two electron bunches delayed by 74 fs. The second electron bunch duration is shown to be ultrashort to match the intensity level of the radiation. Whereas transition radiation was used at longer wavelengths in order to estimate the electron bunch length, this study focuses on the ultrashort structures of the electron beam.

  8. Low-level red laser therapy alters effects of ultraviolet C radiation on Escherichia coli cells.

    PubMed

    Canuto, K S; Sergio, L P S; Guimarães, O R; Geller, M; Paoli, F; Fonseca, A S

    2015-07-10

    Low-level lasers are used at low power densities and doses according to clinical protocols supplied with laser devices or based on professional practice. Although use of these lasers is increasing in many countries, the molecular mechanisms involved in effects of low-level lasers, mainly on DNA, are controversial. In this study, we evaluated the effects of low-level red lasers on survival, filamentation, and morphology of Escherichia coli cells that were exposed to ultraviolet C (UVC) radiation. Exponential and stationary wild-type and uvrA-deficient E. coli cells were exposed to a low-level red laser and in sequence to UVC radiation. Bacterial survival was evaluated to determine the laser protection factor (ratio between the number of viable cells after exposure to the red laser and UVC and the number of viable cells after exposure to UVC). Bacterial filaments were counted to obtain the percentage of filamentation. Area-perimeter ratios were calculated for evaluation of cellular morphology. Experiments were carried out in duplicate and the results are reported as the means of three independent assays. Pre-exposure to a red laser protected wild-type and uvrA-deficient E. coli cells against the lethal effect of UVC radiation, and increased the percentage of filamentation and the area-perimeter ratio, depending on UVC fluence and physiological conditions in the cells. Therapeutic, low-level red laser radiation can induce DNA lesions at a sub-lethal level. Consequences to cells and tissues should be considered when clinical protocols based on this laser are carried out.

  9. Low-level red laser therapy alters effects of ultraviolet C radiation on Escherichia coli cells.

    PubMed

    Canuto, K S; Sergio, L P S; Guimarães, O R; Geller, M; Paoli, F; Fonseca, A S

    2015-10-01

    Low-level lasers are used at low power densities and doses according to clinical protocols supplied with laser devices or based on professional practice. Although use of these lasers is increasing in many countries, the molecular mechanisms involved in effects of low-level lasers, mainly on DNA, are controversial. In this study, we evaluated the effects of low-level red lasers on survival, filamentation, and morphology of Escherichia colicells that were exposed to ultraviolet C (UVC) radiation. Exponential and stationary wild-type and uvrA-deficientE. coli cells were exposed to a low-level red laser and in sequence to UVC radiation. Bacterial survival was evaluated to determine the laser protection factor (ratio between the number of viable cells after exposure to the red laser and UVC and the number of viable cells after exposure to UVC). Bacterial filaments were counted to obtain the percentage of filamentation. Area-perimeter ratios were calculated for evaluation of cellular morphology. Experiments were carried out in duplicate and the results are reported as the means of three independent assays. Pre-exposure to a red laser protected wild-type and uvrA-deficient E. coli cells against the lethal effect of UVC radiation, and increased the percentage of filamentation and the area-perimeter ratio, depending on UVC fluence and physiological conditions in the cells. Therapeutic, low-level red laser radiation can induce DNA lesions at a sub-lethal level. Consequences to cells and tissues should be considered when clinical protocols based on this laser are carried out.

  10. Low-level red laser therapy alters effects of ultraviolet C radiation on Escherichia coli cells

    PubMed Central

    Canuto, K.S.; Sergio, L.P.S.; Guimarães, O.R.; Geller, M.; Paoli, F.; Fonseca, A.S.

    2015-01-01

    Low-level lasers are used at low power densities and doses according to clinical protocols supplied with laser devices or based on professional practice. Although use of these lasers is increasing in many countries, the molecular mechanisms involved in effects of low-level lasers, mainly on DNA, are controversial. In this study, we evaluated the effects of low-level red lasers on survival, filamentation, and morphology of Escherichia colicells that were exposed to ultraviolet C (UVC) radiation. Exponential and stationary wild-type and uvrA-deficientE. coli cells were exposed to a low-level red laser and in sequence to UVC radiation. Bacterial survival was evaluated to determine the laser protection factor (ratio between the number of viable cells after exposure to the red laser and UVC and the number of viable cells after exposure to UVC). Bacterial filaments were counted to obtain the percentage of filamentation. Area-perimeter ratios were calculated for evaluation of cellular morphology. Experiments were carried out in duplicate and the results are reported as the means of three independent assays. Pre-exposure to a red laser protected wild-type and uvrA-deficient E. coli cells against the lethal effect of UVC radiation, and increased the percentage of filamentation and the area-perimeter ratio, depending on UVC fluence and physiological conditions in the cells. Therapeutic, low-level red laser radiation can induce DNA lesions at a sub-lethal level. Consequences to cells and tissues should be considered when clinical protocols based on this laser are carried out. PMID:26445338

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

    NASA Astrophysics Data System (ADS)

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

    1996-01-01

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

  12. Contamination and Radiation Effects on Nonlinear Crystals for Space Laser Systems

    NASA Technical Reports Server (NTRS)

    Abdeldayem, Hossain A.; Dowdye, Edward; Jamison, Tracee; Canham, John; Jaeger, Todd

    2005-01-01

    Space Lasers are vital tools for NASA s space missions and military applications. Although, lasers are highly reliable on the ground, several past space laser missions proved to be short-lived and unreliable. In this communication, we are shedding more light on the contamination and radiation issues, which are the most common causes for optical damages and laser failures in space. At first, we will present results based on the study of liquids and subsequently correlate these results to the particulates of the laser system environment. We present a model explaining how the laser beam traps contaminants against the optical surfaces and cause optical damages and the role of gravity in the process. We also report the results of the second harmonic generation efficiency for nonlinear optical crystals irradiated with high-energy beams of protons. In addition, we are proposing to employ the technique of adsorption to minimize the presence of adsorbing molecules present in the laser compartment.

  13. A comparison of six different ballast water treatment systems based on UV radiation, electrochlorination and chlorine dioxide.

    PubMed

    Stehouwer, Peter Paul; Buma, Anita; Peperzak, Louis

    2015-01-01

    The spread of aquatic invasive species through ballast water is a major ecological and economical threat. Because of this, the International Maritime Organization (IMO) set limits to the concentrations of organisms allowed in ballast water. To meet these limits, ballast water treatment systems (BWTSs) were developed. The main techniques used for ballast water treatment are ultraviolet (UV) radiation and electrochlorination (EC). In this study, phytoplankton regrowth after treatment was followed for six BWTSs. Natural plankton communities were treated and incubated for 20 days. Growth, photosystem II efficiency and species composition were followed. The three UV systems all showed similar patterns of decrease in phytoplankton concentrations followed by regrowth. The two EC and the chlorine dioxide systems showed comparable results. However, UV- and chlorine-based treatment systems showed significantly different responses. Overall, all BWTSs reduced phytoplankton concentrations to below the IMO limits, which represents a reduced risk of aquatic invasions through ballast water.

  14. Measurement capabilities of a compact thermal-type standard of energy unit of pulse laser radiation

    NASA Astrophysics Data System (ADS)

    Skrzeczanowski, Wojciech

    2001-08-01

    New instrument for measurements of laser pulse energy is described. Due to its parameters it can be used as a standard for unit of energy of pulse laser radiation. The instrument consists of a control unit, three sources of laser radiation, two receivers of optical signal, and a laptop. The whole system can be easily transported enabling one to carry out measurements in situ, at customer's, not only in laboratory conditions. This is a very important feature of the instrument because it allows inexpensive calibration and testing of large industrial laser installations and interesting laboratory intercomparisons as well. A method of measurement used in operation of the standard is presented. Main characteristics of the standard are shown. Methods of calculation of uncertainties of measurement during laser energy meters calibration by means of the standard of energy unit of pulse laser radiation are also presented. An alternative measurement option of the standard operating as an energy calibrator for unknown pulse optical radiation source is also available. Some results of testing of laser energy meters at eye-safe wavelength (1.54 micrometer) are presented.

  15. Instantaneous x-ray radiation energy from laser produced polystyrene plasmas for shock ignition conditions

    SciTech Connect

    Shang, Wanli; Wei, Huiyue; Li, Zhichao; Yi, Rongqing; Zhu, Tuo; Song, Tianmin; Huang, Chengwu; Yang, Jiamin

    2013-10-15

    Laser target energy coupling mechanism is crucial in the shock ignition (SI) scheme, and x-ray radiation energy is a non-negligible portion of the laser produced plasma energy. To evaluate the x-ray radiation energy amount at conditions relevant to SI scheme, instantaneous x-ray radiation energy is investigated experimentally with continuum phase plates smoothed lasers irradiating layer polystyrene targets. Comparative laser pulses without and with shock spike are employed. With the measured x-ray angular distribution, full space x-ray radiation energy and conversion efficiency are observed. Instantaneous scaling law of x-ray conversion efficiency is obtained as a function of laser intensity and time. It should be pointed out that the scaling law is available for any laser pulse shape and intensity, with which irradiates polystyrene planar target with intensity from 2 × 10{sup 14} to 1.8 × 10{sup 15} W/cm{sup 2}. Numerical analysis of the laser energy transformation is performed, and the simulation results agree with the experimental data.

  16. Radiation Dose Measurement for High-Intensity Laser Interactions with Solid Targets at SLAC

    SciTech Connect

    Liang, Taiee

    2015-09-25

    A systematic study of photon and neutron radiation doses generated in high-intensity laser-solid interactions is underway at SLAC National Accelerator Laboratory. We found that these laser-solid experiments are being performed using a 25 TW (up to 1 J in 40 fs) femtosecond pulsed Ti:sapphire laser at the Linac Coherent Light Source’s (LCLS) Matter in Extreme Conditions (MEC) facility. Additionally, radiation measurements were performed with passive and active detectors deployed at various locations inside and outside the target chamber. Results from radiation dose measurements for laser-solid experiments at SLAC MEC in 2014 with peak intensity between 1018 to 7.1x1019 W/cm2 are presented.

  17. Surface modification of dental tissues by KrF excimer laser radiation

    NASA Astrophysics Data System (ADS)

    Sivakumar, M.; Oliveira, V.; Vilar, R.

    2007-02-01

    Laser treatment is a promising technique for dental applications such as caries removal, dental hypersensitivity reduction and improvement of the bond strength between dentin and restoration materials. In this study the topographic and morphological changes induced in enamel and dentin surfaces by treating with KrF excimer laser radiation were studied as a function of the number of laser pulses and radiation fluence by scanning electron microscopy and optical profilometry. For enamel, independently of the fluence used, material removal occurs preferentially at the prisms sheaths, leading to the formation of surface pits of a few micrometers. For dentin, a cone-like topography develops when the tubules are approximately parallel to the laser beam direction and the radiation fluence is within the range 0.5 to 1.5 J/cm2. For higher fluences, the treated surfaces are flat and covered with a layer of re-solidified materials.

  18. Investigation of high-Tc superconducting tunnel junction after laser radiation processing

    NASA Astrophysics Data System (ADS)

    Broslavez, U. U.; Fomitchev, A. A.; Yakshin, Mikhail A.

    1995-03-01

    We investigate dynamic resistance (dV/dI) of high-Tc superconducting thin films and tunnel junction after laser radiation processing. The films of YBaCuO were prepared by laser and magnetron ablation on Al2O3 substrates. The tunnel junctions were made by fine silver wires attached to the processing surfaces. The resistance (dV/dI) was determined by a four-probe measurement. The YAG laser operating in Q-switched mode was used to interact with superconductors. The anomaly is observed in the current-voltage curve of the junction after radiation interaction. We observe hysteresis in the shape of V(I) curve. These effects are not observed without laser radiation interaction and in this case the behavior of tunnel junction is described for the standard BCS theory.

  19. Comparison of the effect of UV laser radiation and of a radiomimetic substance on chromatin

    NASA Astrophysics Data System (ADS)

    Radulescu, Irina; Radu, Liliana; Serbanescu, Ruxandra; Nelea, V. D.; Martin, C.; Mihailescu, Ion N.

    1998-07-01

    The damages of the complex of deoxyribonucleic acid (DNA) and proteins from chromatin, produced by the UV laser radiation and/or by treatment with a radiomimetic substance, bleomycin, were compared. The laser radiation and bleomycin effects on chromatin structure were determined by the static and dynamic fluorimetry of chromatin complexes with the DNA specific ligand-- proflavine and by the analysis of tryptophan chromatin intrinsic fluorescence. Time resolved spectroscopy is a sensitive technique which allows to determine the excited state lifetimes of chromatin--proflavine complexes. Also, the percentage contributions to the fluorescence of proflavine, bound and unbound to chromatin DNA, were evaluated. The damages produced by the UV laser radiation on chromatin are similar with those of radiomimetic substance action and consists in DNA and proteins destruction. The DNA damage degree has been determined. The obtained results may constitute some indications in the laser utilization in radiochimiotherapy.

  20. Thermal radiation of laser heated niobium clusters Nb(+)(N), 8 ⩽ N ⩽ 22.

    PubMed

    Hansen, Klavs; Li, Yejun; Kaydashev, Vladimir; Janssens, Ewald

    2014-07-14

    The thermal radiation from small, laser heated, positively charged niobium clusters has been measured. The emitted power was determined by the quenching effect on the metastable decay, employing two different experimental protocols. The radiative power decreases slightly with cluster size and shows no strong size-to-size variations. The magnitude is 40-50 keV/s at the timescale of several microseconds, which is the measured crossover time from evaporative to radiative cooling.

  1. Nonlinear-optical generation of short-wavelength radiation controlled by laser-induced interference structures

    SciTech Connect

    Popov, A K; Kimberg, V V

    1998-03-31

    A study is reported of the combined influence of laser-induced resonances in the energy continuum, of splitting of discrete resonances in the field of several strong radiations, and of absorption of the initial and generated radiations on totally resonant parametric conversion to the short-wavelength range. It is shown that the radiation power can be increased considerably by interference processes involving quantum transitions. (nonlinear optical phenomena and devices)

  2. Neutrophils of the patients with cervical cancer after femtosecond laser radiation in vitro

    NASA Astrophysics Data System (ADS)

    Abakumova, Tatyana; Sysoliatin, Alexey; Antoneeva, Inna; Svetukhin, Vyacheslav; Arslanova, Dinara; Gening, Snezhanna

    2012-03-01

    The cytochemical analysis of the aerobic and anaerobic bactericidal, phagocytic activity, phagocytosis completeness, as well as membrane topology and rigidity has been performed with the Scanning probe microscopy (Solver Pro, NT-MDT, Russia) in neutrophils of the patients with cervical carcinoma treated with the Erbium laser radiation at different intensity. The obtained data reveal a significant effect of the femtosecond laser radiation on neutrophil morphofunctional state in patients with cervical cancer. The efficiency of the femtosecond radiation depends on its intensity and clinical stage of the cervical cancer.

  3. Two-frequency picosecond laser based on composite vanadate crystals with {sigma}-polarised radiation

    SciTech Connect

    Sirotkin, A A; Sadovskiy, S P; Garnov, Sergei V

    2013-07-31

    A two-frequency picosecond laser based on {alpha}-cut Nd:YVO{sub 4}-YVO{sub 4} composite vanadate crystals is experimentally studied for the s-polarised radiation at the {sup 4}F{sub 3/2} - {sup 4}I{sub 11/2} transition with frequency tuning using Fabry-Perot etalons of different thickness. The difference between the radiation wavelengths was tuned within the range of 1.2-4.4 nm. In the mode-locking regime, the two-frequency radiation power was 280 mW at an absorbed pump power of 12 W. (lasers)

  4. Generalized eczematous reaction after fractional carbon dioxide laser therapy for tattoo allergy.

    PubMed

    Meesters, Arne A; De Rie, Menno A; Wolkerstorfer, Albert

    2016-12-01

    Allergic tattoo reactions form a therapeutically difficult entity. Treatment with conventional quality-switched lasers does not completely remove the allergenic particles and may lead to generalized hypersensitivity reactions. Recently, ablative fractional laser therapy was introduced as a treatment for allergic tattoo removal. We present two cases of allergic reactions to red tattoo ink treated with 10,600-nm fractional CO2 laser. At the end of treatment, almost complete removal of red ink accompanied by a significant reduction of symptoms was observed in the first patient, whereas the second patient developed an acute generalized eczematous reaction after five treatments. These findings confirm that ablative fractional laser therapy is capable of significant removal of tattoo ink in an allergic tattoo reaction. However, it implies a risk of generalized hypersensitivity reactions. To our knowledge, this is the first case of a generalized hypersensitivity reaction following treatment of tattoo allergy with the fractional CO2 laser.

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

    PubMed

    Chui, Christopher Hoe Kong; Fong, Poh Him

    2008-03-01

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

  6. Features of gallstone and kidney stone fragmentation by IR-pulsed Nd:YAG laser radiation

    NASA Astrophysics Data System (ADS)

    Batishche, Sergei A.

    1995-05-01

    It is shown that infra-red ((lambda) equals 1064 nm) long pulse (approximately 100 microsecond(s) ) radiation of YAG:Nd laser, operating in free generation regime, effectively fragments gallstones, urinary calculus and kidney stones. The features of the mechanism of this process are investigated. Laser lithotripsy is nowadays a method widely used for fragmentation of gallstones, urinary calculus and kidney stones. Flashlamp pumped dye lasers of microsecond duration are most often used for such purposes. Nevertheless, there are some reports on lithotripsies with nanosecond duration laser pulses (for example, Q-switched YAG:Nd laser). The mechanism of the laser fragmentation of such stones was supposed to be the next. The laser powerful radiation, delivered through the optical fiber, is absorbed by the material of the stone. As a result of such highly localized energy absorption, dense plasma is formed, which expands. Such plasma and vapor, liquid confined, forms a cavitation bubble. This bubble grows, reaches its most dimension and then collapses on itself in some hundreds of micro seconds. Shock waves generated during the growth and the collapse of these bubbles are the origin of fragmentation of the stone. It is necessary to say that there are rather confined data on the hundreds microsecond laser pulse fragmentation especially what concerns the usage of infra-red (IR) YAG:Nd lasers with long laser pulses. Clearing this problem would result in better understanding of the fragmentation mechanism and it could favor development of simple and more reliable laser systems for lithotripsy. In this work we report about investigation of features of an effective fragmentation of gallstones, urinary calculus and kidney stones under exposure of IR ((lambda) equals 1064 nm) radiation of repetitive YAG:Nd laser working in free generation regime.

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

    PubMed Central

    Levine, Zachary H.; Pintar, Adam L.; Dobler, Jeremy T.; Blume, Nathan; Braun, Michael; Scott Zaccheo, T.; Pernini, Timothy G.

    2016-01-01

    Laser absorption spectroscopy (LAS) has been used over the last several decades for the measurement of trace gasses in the atmosphere. For over a decade, LAS measurements from multiple sources and tens of retroreflectors have been combined with sparse-sample tomography methods to estimate the 2-D distribution of trace gas concentrations and underlying fluxes from point-like sources. In this work, we consider the ability of such a system to detect and estimate the position and rate of a single point leak which may arise as a failure mode for carbon dioxide storage. The leak is assumed to be at a constant rate giving rise to a plume with a concentration and distribution that depend on the wind velocity. We demonstrate the ability of our approach to detect a leak using numerical simulation and also present a preliminary measurement. PMID:27453761

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

    DOE PAGES

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

    2016-04-13

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

  9. Modulation of diode laser radiation for the formation of a distance-independent backscattered signal

    NASA Astrophysics Data System (ADS)

    Bukharin, A. V.; Arumov, G. P.; Blikh, Yu. M.; Makarov, V. S.; Turin, A. V.

    2016-10-01

    We propose a probing regime, in which the backscattered signal energy is independent of the distance from the surface of a scattering object. This regime is implemented using a part of the laser radiation power. With respect to the efficiency of using the laser during one measurement, the proposed regime is close to the pseudorandom noise continuous wave lidar regime. Using diode lasers, the regime of the degenerate energy response function and the lidar regime can be implemented in a single device. The relations between the geometric parameters of the probing scheme and the modulation parameters of laser radiation are obtained. The dependence of the linearity range of the diode laser on the relation between the length of the receiving channel near-field zone and the length of the probed trace is substantiated.

  10. A cesium plasma TELEC device for conversion of laser radiation to electric power

    NASA Technical Reports Server (NTRS)

    Britt, E. J.; Rasor, N. S.; Lee, G.; Billman, K. W.

    1978-01-01

    Tests of the thermoelectronic laser energy converter (TELEC) concept are reported. This device has been devised as a means to convert high-average-power laser radiation into electrical energy, a crucial element in any space laser power transmission scheme using the available high-power/efficiency infrared lasers. Theoretical calculations, based upon inverse bremsstrahlung absorption in a cesium plasma, indicate internal conversion efficiency up to 50% with an overall system efficiency of 42%. The experiments reported were made with a test cell designed to confirm the theoretical model rather than demonstrate efficiency; 10.6-micron laser-beam absorption was limited to about 0.001 of the incident beam by the short absorption region. Nevertheless, confirmatory results were obtained, and the conversion of absorbed radiation to electric power is estimated to be near 10%.

  11. Stress relaxation and cartilage shaping under laser radiation

    NASA Astrophysics Data System (ADS)

    Sobol, Emil N.; Sviridov, Alexander P.; Bagratashvili, Victor N.; Omelchenko, Alexander I.; Ovchinnikov, Yuriy M.; Shekhter, Anatoliy B.; Downes, S.; Howdle, Steven; Jones, Nicholas; Lowe, J.

    1996-05-01

    The problem of a purposeful change of the shape of cartilage is of great importance for otolaryngology, orthopaedics, and plastic surgery. In 1992 we have found a possibility of controlled shaping of cartilage under moderate laser heating. This paper presents new results in studies of that phenomenon. We have measured temperature and stress in a tissue undergoing to irradiation with a Holmium laser. Study of cartilage structure allowed us to find conditions for laser shaping without pronounced alterations in the structure of matrix.

  12. Measurement of nitrogen dioxide in cigarette smoke using quantum cascade tunable infrared laser differential absorption spectroscopy (TILDAS)

    NASA Astrophysics Data System (ADS)

    Shorter, Joanne H.; Nelson, David D.; Zahniser, Mark S.; Parrish, Milton E.; Crawford, Danielle R.; Gee, Diane L.

    2006-04-01

    Although nitrogen dioxide (NO 2) has been previously reported to be present in cigarette smoke, the concentration estimates were derived from kinetic calculations or from measurements of aged smoke, where NO 2 was formed some time after the puff was taken. The objective of this work was to use tunable infrared laser differential absorption spectroscopy (TILDAS) equipped with a quantum cascade (QC) laser to determine if NO 2 could be detected and quantified in a fresh puff of cigarette smoke. A temporal resolution of ˜0.16 s allowed measurements to be taken directly as the NO 2 was formed during the puff. Sidestream cigarette smoke was sampled to determine if NO 2 could be detected using TILDAS. Experiments were conducted using 2R4F Kentucky Reference cigarettes with and without a Cambridge filter pad. NO 2 was detected only in the lighting puff of whole mainstream smoke (without a Cambridge filter pad), with no NO 2 detected in the subsequent puffs. The measurement precision was ˜1.0 ppbV Hz -1/2, which allows a detection limit of ˜0.2 ng in a 35 ml puff volume. More NO 2 was generated in the lighting puff using a match or blue flame lighter (29 ± 21 ng) than when using an electric lighter (9 ± 3 ng). In the presence of a Cambridge filter pad, NO 2 was observed in the gas phase mainstream smoke for every puff (total of 200 ± 30 ng/cigarette) and is most likely due to smoke chemistry taking place on the Cambridge filter pad during the smoke collection process. Nitrogen dioxide was observed continuously in the sidestream smoke starting with the lighting puff.

  13. Theoretical Investigation of Laser-Radiation Effects on Satellite Solar Cells

    NASA Astrophysics Data System (ADS)

    Abdel-Hadi, Yasser; El-Hameed, Afaf; Hamdy, Ola

    This research concerns with the studying of laser-powered solar panels for space applications. A model describing the laser effects on satellite solar cell has been developed. These effects are studied theoretically in order to determine the performance limits of the solar cells when they are powered by laser radiation during the satellite eclipse. A comparison between some different common types of the solar cells used for these purpose is considered in this study. The obtained results are reported to optimize the use of laser-powered satellites.

  14. A novel method of carbon dioxide clumped isotope analysis with tunable infra-red laser direct absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Prokhorov, Ivan; Kluge, Tobias; Janssen, Christof

    2016-04-01

    Precise clumped isotopes analysis of carbon dioxide opens up new horizons of atmospheric and biogeochemical research. Recent advances in laser and spectroscopic techniques provides us necessary instrumentation to access extremely low sub-permill variations of multiply-substituted isotopologues. We present an advanced analysis method of carbon dioxide clumped isotopes using direct absorption spectroscopy. Our assessments predict the ultimate precision of the new method on the sub-permill level comparable to state of the art mass spectrometry. Among the most auspicious intrinsic properties of this method we highlight genuine Δ16O13C18O and Δ16O13C18O measurements without isobaric interference, measurement cycle duration of several minutes versus hours for mass spectrometric analysis, reduced sample size of ˜ 10 μmol and high flexibility, allowing us to perform in-situ measurements. The pilot version of the instrument is being developed in an international collaboration framework between Heidelberg University, Germany and Pierre and Marie Curie University, Paris, France. It employs two continuous interband quantum cascade lasers tuned at 4.439 μm and 4.329 μm to measure doubly ( 16O13C18O, 16O13C17O) and singly ( 16O12C16O, 16O13C16O, 16O12C17O, 16O12C18O) substituted isotopologues, respectively. Two identical Herriot cells are filled with dry pure CO2 sample and reference gas at working pressure of 1 - 10 mbar. Cells provide optical path lengths of ˜ 17 m for the laser tuned at doubly substituted isotopologues lines and use a single pass for the laser tuned at the stronger lines of singly substituted isotopologues. Light outside of the gas cells is coupled into optical fiber to avoid absorption by ambient air CO2. Simulations predict sub-permill precision at working pressure of 1 mbar and room temperature stabilised at the ±10 mK level. Our prime target is to apply the proposed method for continuous in-situ analysis of CO2. We are foreseeing potential

  15. Absorption and scattering of laser radiation by the diffusion flame of aviation kerosene

    SciTech Connect

    Gvozdev, S V; Glova, A F; Dubrovskii, V Yu; Durmanov, S T; Krasyukov, A G; Lysikov, A Yu; Smirnov, G V; Solomakhin, V B

    2012-04-30

    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 {approx}10{sup 3} - 5 Multiplication-Sign 10{sup 4} W cm{sup -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.

  16. Expansion of radiative cooling of the laser induced plasma

    SciTech Connect

    Wen, Sy-Bor; Mao, Xianglei; Liu, Chunyi; Greif, Ralph; Russo,Richard

    2006-05-05

    To study the expansion and cooling process of the laser induced plasma generated by nanosecond pulsed laser ablation, experiments have been conducted which measure the position of the external shockwaves and the temperature of the vapor plumes. The positions of external shockwaves were determined by a femtosecond laser time-resolved imaging system. Vapor plume temperature was determined from spectroscopic measurements of the plasma emission lines. A model which considers the mass, momentum, and energy conservation of the region affected by the laser energy was developed. It shows good agreement to the experimental data.

  17. Combination of fiber-guided pulsed erbium and holmium laser radiation for tissue ablation under water

    NASA Astrophysics Data System (ADS)

    Pratisto, Hans; Frenz, Martin; Ith, Michael; Altermatt, Hans J.; Jansen, E. Duco; Weber, Heinz P.

    1996-07-01

    Because of the high absorption of near-infrared laser radiation in biological tissue, erbium lasers and holmium lasers emitting at 3 and 2 mu m, respectively, have been proven to have optimal qualities for cutting or welding and coagulating tissue. To combine the advantages of both wavelengths, we realized a multiwavelength laser system by simultaneously guiding erbium and holmium laser radiation by means of a single zirconium fluoride (ZrF4) fiber. Laser-induced channel formation in water and poly(acrylamide) gel was investigated by the use of a time-resolved flash-photography setup, while pressure transients were recorded simultaneously with a needle hydrophone. The shapes and depths of vapor channels produced in water and in a submerged gel after single erbium and after combination erbium-holmium radiation delivered by means of a 400- mu m ZrF4 fiber were measured. Transmission measurements were performed to determine the amount of pulse energy available for tissue ablation. The effects of laser wavelength and the delay time between pulses of different wavelengths on the photomechanical and photothermal responses of meniscal tissue were evaluated in vitro by the use of histology. It was observed that the use of a short (200- mu s, 100-mJ) holmium laser pulse as a prepulse to generate a vapor bubble through which the ablating erbium laser pulse can be transmitted (delay time, 100 mu s) increases the cutting depth in meniscus from 450 to 1120 mu m as compared with the depth following a single erbium pulse. The results indicate that a combination of erbium and holmium laser radiation precisely and efficiently cuts tissue under water with 20-50- mu m collateral tissue damage. wave, cavitation, channel formation, infrared-fiber-delivery system, tissue damage, cartilage.

  18. Effect of smoke evacuation on limiting thermal damage when using the carbon dioxide laser for cutaneous surgery

    NASA Astrophysics Data System (ADS)

    Waters, Ruth A.; Thomas, J. M.; Clement, Marc; Davies, S.

    1990-06-01

    We have conducted a study of the use of the carbon dioxide (C02) laser for ablation of multiple cutaneous recurrences of melanoma. Lesions of primary malignant melanoma are usually widely excised to try and prevent local recurrence. Despite this, recurrent cutaneous lesions do occur. These lesions may be small and numerous making local excision impractical. Hyperthermic isolated limb perfusion has shown some success in controlling the local disease but this procedure has a significant morbidty, some patients show only a limited response and post-perfusion recurrences are common.1 Also, in some patients, thelesions will not be confined to a limb. No other method of local control has provided an ideal solution and amputation has sometimes been a last resort. We have therefore selected patients for laser ablation if they have had lesions too numerous for local excision, or have had recurrences following perfusion or were otherwise suitable for perfusion. The lesions were vaporized under local or general anaesthesia according to their size and number. The wounds were then left to heal by secondary intention. Simple dry dressings were applied and all patients were discharged home within 24 hours. In total we have treated over 1,500 lesions in 30 patients. The results of the initial study have been very encouraging. The procedure is quick and simple with absent or minimal post-operative pain. Although the incidence of recurrent tumour at a previously lasered site is less than 1%, new tumours may develop at other sites. These are amenable to further laser treatment.

  19. Ex vivo investigations of laser auricular cartilage reshaping with carbon dioxide spray cooling in a rabbit model.

    PubMed

    Wu, Edward C; Sun, Victor; Manuel, Cyrus T; Protsenko, Dmitriy E; Jia, Wangcun; Nelson, J Stuart; Wong, Brian J F

    2013-11-01

    Laser cartilage reshaping (LCR) with cryogen spray cooling is a promising modality for producing cartilage shape change while reducing cutaneous thermal injury. However, LCR in thicker tissues, such as auricular cartilage, requires higher laser power, thus increasing cooling requirements. To eliminate the risks of freeze injury characteristic of high cryogen spray pulse rates, a carbon dioxide (CO2) spray, which evaporates rapidly from the skin, has been proposed as the cooling medium. This study aims to identify parameter sets which produce clinically significant reshaping while producing minimal skin thermal injury in LCR with CO2 spray cooling in ex vivo rabbit auricular cartilage. Excised whole rabbit ears were mechanically deformed around a cylindrical jig and irradiated with a 1.45-μm wavelength diode laser (fluence 12-14 J/cm(2) per pulse, four to six pulse cycles per irradiation site, five to six irradiation sites per row for four rows on each sample) with concomitant application of CO2 spray (pulse duration 33-85 ms) to the skin surface. Bend angle measurements were performed before and after irradiation, and the change quantified. Surface temperature distributions were measured during irradiation/cooling. Maximum skin surface temperature ranged between 49.0 to 97.6 °C following four heating/cooling cycles. Significant reshaping was achieved with all laser dosimetry values with a 50-70 °C difference noted between controls (no cooling) and irradiated ears. Increasing cooling pulse duration yielded progressively improved gross skin protection during irradiation. CO2 spray cooling may potentially serve as an alternative to traditional cryogen spray cooling in LCR and may be the preferred cooling medium for thicker tissues. Future studies evaluating preclinical efficacy in an in vivo rabbit model are in progress.

  20. Carbon dioxide laser ablation with immediate autografting in a full-thickness porcine burn model.

    PubMed Central

    Glatter, R D; Goldberg, J S; Schomacker, K T; Compton, C C; Flotte, T J; Bua, D P; Greaves, K W; Nishioka, N S; Sheridan, R L

    1998-01-01

    OBJECTIVE: To compare the long-term clinical and histologic outcome of immediate autografting of full-thickness burn wounds ablated with a high-power continuous-wave CO2 laser to sharply débrided wounds in a porcine model. SUMMARY BACKGROUND DATA: Continuous-wave CO2 lasers have performed poorly as tools for burn excision because the large amount of thermal damage to viable subeschar tissues precluded successful autografting. However, a new technique, in which a high-power laser is rapidly scanned over the eschar, results in eschar vaporization without significant damage to underlying viable tissues, allowing successful immediate autografting. METHODS: Full-thickness paravertebral burn wounds measuring 36 cm2 were created on 11 farm swine. Wounds were ablated to adipose tissue 48 hours later using either a surgical blade or a 150-Watt continuous-wave CO2 laser deflected by an x-y galvanometric scanner that translated the beam over the tissue surface, removing 200 microm of tissue per scan. Both sites were immediately autografted and serially evaluated clinically and histologically for 180 days. RESULTS: The laser-treated sites were nearly bloodless. The mean residual thermal damage was 0.18+/-0.05 mm. The mean graft take was 96+/-11% in manual sites and 93+/-8% in laser sites. On postoperative day 7, the thickness of granulation tissue at the graft-wound bed interface was greater in laser-debrided sites. By postoperative day 180, the manual and laser sites were histologically identical. Vancouver scar assessment revealed no differences in scarring at postoperative day 180. CONCLUSIONS: Long-term scarring, based on Vancouver scar assessments and histologic evaluation, was equivalent at 6 months in laser-ablated and sharply excised sites. Should this technology become practical, the potential clinical implications include a reduction in surgical blood loss without sacrifice of immediate engraftment rates or long-term outcome. Images Figure 1. Figure 2. Figure 3

  1. Calculation of laser induced impulse based on the laser supported detonation wave model with dissociation, ionization and radiation

    SciTech Connect

    Gan, Li Mousen, Cheng; Xiaokang, Li

    2014-03-15

    In the laser intensity range that the laser supported detonation (LSD) wave can be maintained, dissociation, ionization and radiation take a substantial part of the incidence laser energy. There is little treatment on the phenomenon in the existing models, which brings obvious discrepancies between their predictions and the experiment results. Taking into account the impact of dissociation, ionization and radiation in the conservations of mass, momentum and energy, a modified LSD wave model is developed which fits the experimental data more effectively rather than the existing models. Taking into consideration the pressure decay of the normal and the radial rarefaction, the laser induced impulse that is delivered to the target surface is calculated in the air; and the dependencies of impulse performance on laser intensity, pulse width, ambient pressure and spot size are indicated. The results confirm that the dissociation is the pivotal factor of the appearance of the momentum coupling coefficient extremum. This study focuses on a more thorough understanding of LSD and the interaction between laser and matter.

  2. Laser radiation in the treatment of prosthetic graft stenosis. A preliminary study of prosthesis damage by laser energy

    SciTech Connect

    Seeger, J.M.; Abela, G.S.; Klingman, N.

    1987-09-01

    Transluminal laser recanalization is potentially an important new treatment of anastomotic intimal hyperplasia. However, currently used grafts or sutures may be damaged by laser radiation at power and energy levels required for plaque removal. To investigate this problem, two commonly used grafts (Dacron and polytetrafluoroethylene (PTFE)) and two types of vascular suture (polypropylene and PTFE) were exposed to argon laser radiation in vitro. Dacron and PTFE grafts recovered from amputations were also studied to determine whether graft healing affected graft resistance to laser damage. Power and energy levels required to perforate atherosclerotic superficial femoral arteries were determined for comparison. PTFE grafts were significantly (1.5 to 7 times) more resistant to perforation by laser energy than atherosclerotic arteries under all conditions. In contrast, Dacron grafts perforated at power and energy levels one half to one third of that required for vaporization of atherosclerotic plaque. PTFE sutures remained intact at power and energy levels above the levels that perforated atherosclerotic arteries, whereas polypropylene sutures were destroyed by very low levels of power and energy (0.5 joules at 0.5 watts). Because of the variable levels of power and energy that damage different types of prosthetic grafts and sutures, laser angioplasty should only be investigated clinically as a therapy for anastomotic intimal hyperplasia when PTFE grafts and sutures are present.

  3. Calculation of laser induced impulse based on the laser supported detonation wave model with dissociation, ionization and radiation

    NASA Astrophysics Data System (ADS)

    Gan, Li; Mousen, Cheng; Xiaokang, Li

    2014-03-01

    In the laser intensity range that the laser supported detonation (LSD) wave can be maintained, dissociation, ionization and radiation take a substantial part of the incidence laser energy. There is little treatment on the phenomenon in the existing models, which brings obvious discrepancies between their predictions and the experiment results. Taking into account the impact of dissociation, ionization and radiation in the conservations of mass, momentum and energy, a modified LSD wave model is developed which fits the experimental data more effectively rather than the existing models. Taking into consideration the pressure decay of the normal and the radial rarefaction, the laser induced impulse that is delivered to the target surface is calculated in the air; and the dependencies of impulse performance on laser intensity, pulse width, ambient pressure and spot size are indicated. The results confirm that the dissociation is the pivotal factor of the appearance of the momentum coupling coefficient extremum. This study focuses on a more thorough understanding of LSD and the interaction between laser and matter.

  4. Safe and effective carbon dioxide laser skin resurfacing of the neck.

    PubMed

    Kilmer, Suzanne L; Chotzen, Vera A; Silva, Susan K; McClaren, Marla L

    2006-08-01

    CO2 laser skin resurfacing remains the gold standard for treatment of photoaged facial skin. It can be used onto the neck to further blend in the treated area with non-treated, adjacent photodamaged skin as well as improve the superficial textural quality of the neck skin. This article provides an overview of laser skin resurfacing of the neck, including pre-operative evaluation, patient education and selection, laser settings and technique used, post-operative care, and identification and treatment of possible complications.

  5. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Structure of flows due to interaction of CO2 laser pulse pairs with a target in air

    NASA Astrophysics Data System (ADS)

    Bakeev, A. A.; Nikolashina, L. I.; Potashkin, M. N.; Prokopenko, N. V.

    1991-06-01

    An analysis is made of two pulses from an electric-discharge CO2 laser, of 6-12 μs duration and separated in time, incident on a target surrounded by air of normal density. The main attention is concentrated on breakdown of air by the second pulse at a boundary separating the "cold gas" and the plasma generated by the first pulse ("hot gas"). A gasdynamic system of waves is then generated. It consists of an absorption wave traveling along the cold gas opposite to the laser radiation and a wave propagating along the hot gas toward the target. The best agreement between the theory and experiment is obtained employing a model in which an absorption wave travels along the hot gas in an overcompressed detonation regime. The density of the radiation flux needed to maintain such a wave is 20-30% of the average density of the laser radiation flux carried by the second pulse.

  6. Atmospheric propagation of high power laser radiation at different weather conditions

    NASA Astrophysics Data System (ADS)

    Pargmann, Carsten; Hall, Thomas; Duschek, Frank; Handke, Jürgen

    2016-05-01

    Applications based on the propagation of high power laser radiation through the atmosphere are limited in range and effect, due to weather dependent beam wandering, beam deterioration, and scattering processes. Security and defense related application examples are countermeasures against hostile projectiles and the powering of satellites and aircrafts. For an examination of the correlations between weather condition and laser beam characteristics DLR operates at Lampoldshausen a 130 m long free transmission laser test range. Sensors around this test range continuously monitor turbulence strength, visibility, precipitation, temperature, and wind speed. High power laser radiation is obtained by a TruDisk 6001 disk laser (Trumpf company) yielding a maximum output power of 6 kW at a wavelength of 1030 nm. The laser beam is expanded to 180 mm and focused along the beam path. Power and intensity distribution are measured before and after propagation, providing information about the atmospheric transmission and alterations of diameter and position of the laser beam. Backscattered laser light is acquired by a photo receiver. As a result, measurements performed at different weather conditions show a couple of correlations to the characteristics of the laser beam. The experimental results are compared to a numerical analysis. The calculations are based on the Maxwell wave equation in Fresnel approximation. The turbulence is considered by the introduction of phase screens and the "von Karman" spectrum.

  7. Recent Progress in Development of a Laser Based, Ultra-High Precision Isotope Monitor for Carbon Dioxide

    NASA Astrophysics Data System (ADS)

    Nelson, D. D.; McManus, J. B.; Herndon, S. C.; Zahniser, M. S.

    2015-12-01

    Greenhouse gas (GHG) emissions are the primary drivers of global climate change and hence there is a crucial need to quantify their sources and sinks. A general technique to help constrain source and sink strengths in GHG exchange processes is the analysis of the relative proportions of isotopic variants of GHG's. Very high precision measurements of isotopologue ratios are necessary in order to identify sources and sinks because the characteristic changes are small. The standard method of isotopologue measurement has been mass spectrometry, but this technique typically requires significant sample preparation and relatively high instrument maintenance. Laser spectroscopy has the potential to ease these burdens and also to allow easy separation and analysis of interfering isobars such as 13C-CO2 and 17O-CO2. We present recent results demonstrating ultra-high precision measurements of carbon dioxide isotope ratios which rival the accuracy of mass spectrometric measurements. These measurements were performed using Tunable Infrared Laser Direct Absorption Spectroscopy (TILDAS). We have developed a method for analyzing air samples from canisters by alternately and rapidly trapping sample gas and working reference gas in the optical cell. Using this technique, we have obtained isotopic measurement precisions of ~7 per meg for both 13C-CO2 and 18O-CO2 while measuring trapped ambient air samples with volumes as small as 200 ml with a 16 minute measurement duration. The figure shows a histogram of 2 minute measurements. Our current measurement precision for 17O-CO2 is 30 per meg, but we expect to reduce this to 10 per meg by working in a better spectral region. Our ultimate goal is to create an automated, ultra-high accuracy carbon dioxide isotope monitor able to quantify 13C-, 18O-, and 17O-CO2at the 10 per meg level using small (~100 standard ml), discreet air samples. We will also discuss recent progress in the measurement of the clumped isotopes of carbon dioxide in

  8. A new method and device of aligning patient setup lasers in radiation therapy.

    PubMed

    Hwang, Ui-Jung; Jo, Kwanghyun; Lim, Young Kyung; Kwak, Jung Won; Choi, Sang Hyuon; Jeong, Chiyoung; Kim, Mi Young; Jeong, Jong Hwi; Shin, Dongho; Lee, Se Byeong; Park, Jeong-Hoon; Park, Sung Yong; Kim, Siyong

    2016-01-08

    The aim of this study is to develop a new method to align the patient setup lasers in a radiation therapy treatment room and examine its validity and efficiency. The new laser alignment method is realized by a device composed of both a metallic base plate and a few acrylic transparent plates. Except one, every plate has either a crosshair line (CHL) or a single vertical line that is used for alignment. Two holders for radiochromic film insertion are prepared in the device to find a radiation isocenter. The right laser positions can be found optically by matching the shadows of all the CHLs in the gantry head and the device. The reproducibility, accuracy, and efficiency of laser alignment and the dependency on the position error of the light source were evaluated by comparing the means and the standard deviations of the measured laser positions. After the optical alignment of the lasers, the radiation isocenter was found by the gantry and collimator star shots, and then the lasers were translated parallel to the isocenter. In the laser position reproducibility test, the mean and standard deviation on the wall of treatment room were 32.3 ± 0.93 mm for the new method whereas they were 33.4 ± 1.49 mm for the conventional method. The mean alignment accuracy was 1.4 mm for the new method, and 2.1 mm for the conventional method on the walls. In the test of the dependency on the light source position error, the mean laser position was shifted just by a similar amount of the shift of the light source in the new method, but it was greatly magnified in the conventional method. In this study, a new laser alignment method was devised and evaluated successfully. The new method provided more accurate, more reproducible, and faster alignment of the lasers than the conventional method.

  9. Regeneration of spine disc and joint cartilages under temporal and space modulated laser radiation

    NASA Astrophysics Data System (ADS)

    Sobol, E.; Shekhter, A.; Baskov, A.; Baskov, V.; Baum, O.; Borchshenko, I.; Golubev, V.; Guller, A.; Kolyshev, I.; Omeltchenko, A.; Sviridov, A.; Zakharkina, O.

    2009-02-01

    The effect of laser radiation on the generation of hyaline cartilage in spine disc and joints has been demonstrated. The paper considers physical processes and mechanisms of laser regeneration, presents results of investigations aimed to optimize laser settings and to develop feedback control system for laser reconstruction of spine discs. Possible mechanisms of laser-induced regeneration include: (1) Space and temporary modulated laser beam induces nonhomogeneous and pulse repetitive thermal expansion and stress in the irradiated zone of cartilage. Mechanical effect due to controllable thermal expansion of the tissue and micro and nano gas bubbles formation in the course of the moderate (up to 45-50 oC) heating of the NP activate biological cells (chondrocytes) and promote cartilage regeneration. (2) Nondestructive laser radiation leads to the formation of nano and micro-pores in cartilage matrix. That promotes water permeability and increases the feeding of biological cells. Results provide the scientific and engineering basis for the novel low-invasive laser procedures to be used in orthopedics for the treatment cartilages of spine and joints. The technology and equipment for laser reconstruction of spine discs have been tested first on animals, and then in a clinical trial. Since 2001 the laser reconstruction of intervertebral discs have been performed for 340 patients with chronic symptoms of low back or neck pain who failed to improve with non-operative care. Substantial relief of back pain was obtained in 90% of patients treated who returned to their daily activities. The experiments on reparation of the defects in articular cartilage of the porcine joints under temporal and spase modulated laser radiation have shown promising results.

  10. Direct modification of bioactive phenothiazines by exposure to laser radiation.

    PubMed

    Pascu, Mihail-Lucian; Nastasa, Viorel; Smarandache, Adriana; Militaru, Andra; Martins, Ana; Viveiros, Miguel; Boni, Mihai; Andrei, Ionut Relu; Pascu, Alexandru; Staicu, Angela; Molnar, Joseph; Fanning, Seamus; Amaral, Leonard

    2011-05-01

    Whereas exposure of combinations of a phenothiazine and bacterium to incoherent UV increases the activity of the phenothiazine, exposure of the phenothiazine alone does not yield an increase of its activity. Because the laser beam energy is greater than that produced by the incoherent UV sources, exposure of phenothiazines to specific lasers may yield molecules with altered activities over that of the unexposed parent. Chlorpromazine, thioridazine and promethazine active against bacteria were exposed to two distinct lasers for varying periods of time. Absorption and fluorescence spectra were conducted prior to and post-exposure and the products of laser exposure evaluated for activity against a Staphylococcus aureus ATCC strain via a disk susceptibility assay. Exposure to lasers alters the absorption/fluorescence spectra of the phenothiazines; reduces the activity of thioridazine against the test bacterium; produces a highly active chlorpromazine compound against the test organism. Exposure of phenothiazines to lasers alters their structure that results in altered activity against a bacterium. This is the first report that lasers can alter the physico-chemico characteristics to the extent that altered bioactivity results. Exposure to lasers is expected to yield compounds that are difficult to make via chemical manipulation methods. A survey of selected patents of interest, even co-lateral for the subject of this article is shortly made.

  11. Powerful neodymium laser radiation for the treatment of facial carcinoma: 5 year follow-up data.

    PubMed

    Moskalik, Konstantin; Kozlow, Alexander; Demin, Eugeny; Boiko, Ernest

    2010-01-01

    A retrospective non-comparative follow-up study was performed to evaluate the curative efficacy of powerful neodymium laser radiation (λ = 1,060 nm) for the treatment of 2,837 patients with 3,001 histologically confirmed facial skin carcinoma lesions of stages T1-2N0M0: 2,743 primary basal cell carcinomas (BCC), 172 recurrent limited basal cell carcinomas (RLBCC), and 86 primary squamous cells carcinomas (SCC). All patients were followed-up from 5 to 11 years (mean: 8.2 years; median: 7.0 years) after treatment. The overall recurrence rate (RR) after treatment with laser radiation of facial carcinomas was 2.5% of all irradiated tumours (mean: 13.4 months; median: 11.0 months). Patients with BCC treated by radiation with the pulsed Neodymium (Nd) laser developed RR in 2.2% of cases and patients treated with the Nd:YAG laser had RR of 3.1%. Recurrences following treatment for RLBCC, and those of SCC, after irradiation with the Nd laser appeared in 4.1% and 4.6% of patients, respectively. Neodymium laser radiation is a safe and effective means of treating facial carcinomas of stages T1-2N0M0 with good cosmetic results.

  12. Development of Laser Plasma X-ray Microbeam Irradiation System and Radiation Biological Application

    NASA Astrophysics Data System (ADS)

    Sato, Katsutoshi; Nishikino, Masaharu; Numasaki, Hodaka; Kawachi, Tetsuya; Teshima, Teruki; Nishimura, Hiroaki

    Laser plasma x-ray source has the features such as ultra short pulse, high brilliance, monochromaticity, and focusing ability. These features are excellent compared with conventional x-ray source. In order to apply the laser plasma x-ray source to the biomedical study and to more closely research the radiobilogical responce of the cancer cell such as radiation induced bystander effect, we have developed x-ray microbeam system using laser plasma x-ray source. The absorbed dose of laser plasma x-ray was estimated with Gafchromic EBT film and DNA double strand breaks on the cells were detected by immunofluorescence staining. When the cells were irradiated with laser plasma x-ray, the circular regions existing γ-H2AX positive cells were clearly identified. The usefulness of the laser plasma x-ray on the radiobiological study was proved in this research.

  13. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Plasma-mediated surface evaporation of an aluminium target in vacuum under UV laser irradiation

    NASA Astrophysics Data System (ADS)

    Mazhukin, V. I.; Nosov, V. V.

    2005-05-01

    Mathematical simulation is employed to investigate the dynamics of evaporation and condensation on the surface of a metal target under the conditions of plasma production in the vaporised material exposed to the 0.248-μm UV radiation of a KrF laser with the intensity G0= 2×108—109 W cm-2, and a pulse duration τ= 20 ns. A transient two-dimensional mathematical model is used, which includes, for the condensed medium, the heat conduction equation with the Stefan boundary condition and additional kinetic conditions at the evaporation surface and, for the vapour, the equations of radiative gas dynamics and laser radiation transfer supplemented with tabular data for the parameters of the equations of state and absorption coefficients. The target evaporation in vacuum induced by the UV radiation was found to occur during the laser pulse and is divided into two characteristic stages: initial evaporation with a sound velocity and subsonic evaporation after the plasma production. At the subsonic evaporation stage, one part of the laser radiation passes through the plasma and is absorbed by the target surface and another part is absorbed in a thin plasma layer near the surface to produce a high pressure, which significantly moderates the vapour ejection. After completion of the pulse, a part of the vaporised material is condensed on the surface, both in the evaporation region and some distance away from it due to the lateral expansion of the plasma cloud.

  14. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Interaction of a smoothed laser beam with supercritical-density porous targets on the ABC facility

    NASA Astrophysics Data System (ADS)

    Strangio, C.; Caruso, A.; Gus'kov, Sergei Yu; Rozanov, Vladislav B.; Rupasov, A. A.

    2006-05-01

    We present the results of experiments on the interaction of laser radiation with low-density porous targets performed on the ABC facility at the ENEA Research Centre (Frascati, Italy). Porous plastic targets with densities of 5 and 20 mg cm-3 were irradiated by a focused neodymium-laser beam at the fundamental frequency (λ = 1.054 μm) at a radiation intensity of 1013 W cm-2 at the target. The beam was preliminarily allowed to pass through an optical system intended to spatially smooth the radiation intensity over the beam cross section. The use a smoothed beam was important to discover in the plasma and in the accelerated dense material the features related to the porous structure of the target under conditions which rule out the effect of the inhomogeneities of the heating beam itself. The spatial plasma structure in the laser beam—target interaction region and at the rear side of the target were investigated by using optical schlieren plasma photography. The time dependent transmission of the laser radiation through the target was also investigated by imaging the target in transmitted radiation to a properly masked photodiode.

  15. A molecular dynamics study of radiation induced diffusion in uranium dioxide

    NASA Astrophysics Data System (ADS)

    Martin, G.; Maillard, S.; Brutzel, L. Van; Garcia, P.; Dorado, B.; Valot, C.

    2009-03-01

    The nuclear oxide fuels are submitted 'in-pile' to strong structural and chemical modifications due to the fissions and temperature. The diffusion of species is notably the result of a thermal activation and of radiation induced diffusion. This study proposes to estimate to what extent the radiation induced diffusion contributes to the diffusion of lattice atoms in UO2. Irradiations are simulated using molecular dynamics simulation by displacement cascades induced by uranium primary knock-on atoms between 1 and 80 keV. As atoms are easier to displace when their vibration amplitude increases, the temperature range which have been investigated is 300-1400 K. Cascade overlaps were also simulated. The material is shown to melt at the end of cascades, yielding a reduced threshold energy displacement. The nuclear contribution to the radiation induced diffusion is compared to thermally activated diffusion under in-reactor and long-term storage conditions.

  16. The influence of laser clipped by the laser entrance hole on hohlraum radiation measurement on Shenguang-III prototype

    SciTech Connect

    Yang, Dong; Li, Zhichao; Guo, Liang; Li, Sanwei; Yi, Rongqing; Song, Tianming; Zhang, Huan; Wang, Zhebin; Jiang, Xiaohua; Jiang, Shaoen; Ding, Yongkun

    2014-03-15

    Measuring the x-ray flux exiting the target's laser entrance hole (LEH) is the most common diagnostic that quantifies the x-ray intensity inside the laser-driven hohlraum. However, this signal accounts for only a small portion of the incident laser power and thus is likely to be affected by unwanted x-ray background from non-target area, leading to an overestimation of the hohlraum drive. Unwanted emission might be produced when the laser light is clipped by the LEH (LEH clipping) because of a lack of clearance for laser spot, or with a laser spot comprising of discrete structure, or even with a poor pointing accuracy. Its influence on the hohlraum radiation diagnostic is investigated on Shenguang-III prototype laser facility with the typical 1 ns square pulse. The experiment employed three types of targets to excite the unwanted x-ray background from LEH clipping, unconverted light, and both effects, respectively. This work gives an absolute evaluation of x-ray produced by the LEH clipping, which is measured by flat-response x-ray detectors (FXRD) at multiple view angles. The result indicates that there is little variation in measured emission to various view angles, because the unwanted x-rays are mainly generated at the side face of the LEH lip when laser is obliquely incident. Therefore, the LEH clipping brings more overestimation in hohlraum radiation measurement at larger view angle since the hohlraum LEH as an emitting source viewed by FXRD is decreased as the view angle increases. In our condition, the LEH clipping contributes 2%–3.5% overestimation to the hohlraum flux measurement.

  17. Ordered many-electron motions in atoms and x-ray lasers. [Subpicosecond ultraviolet laser radiation

    SciTech Connect

    Rhodes, C.K.

    1986-01-01

    Subpicosecond ultraviolet laser technology is enabling the exploration of nonlinear atomic interactions with electric field strengths considerably in excess of an atomic unit. As this regime is approached, experiments studying multiple ionization, photoelectron energy spectra, and harmonically produced radiation all exhibit strong nonlinear coupling. Peak total energy transfer rates on the order of approx.2 x 10/sup -4/ W/atom have been observed at an intensity of approx.10/sup 16/ W/cm/sup 2/, and it is expected that energy transfer rates approaching approx.0.1 to 1 W/atom will occur under more extreme conditions for which the ultraviolet electric field E is significantly greater than e/a/sub 0//sup 2/. In this high intensity regime, a wide range of new nonlinear phenomena will be open to study. These will include the possibility of ordered driven motions in atoms, molecules, and plasmas, mechanisms involving collisions, and relativistic processes such as electron-positron pair production. An understanding of these physical interactions may provide a basis for the generation of stimulated emission in the x-ray range. 100 refs., 8 figs.

  18. Theoretical Study of Ultra-Relativistic Laser Electron Interaction with Radiation Reaction by Quantum Description

    NASA Astrophysics Data System (ADS)

    Seto, Keita; Nagatomo, Hideo; Koga, James; Mima, Kunioki

    In the near future, the intensity of the ultra-short pulse laser will reach to 1022 W/cm2. When an electron is irradiated by this laser, the electron's behavior is relativistic with significant bremsstrahlung. This radiation from the electron is regarded as the energy loss of electron. Therefore, the electron's motion changes because of the kinetic energy changing. This radiation effect on the charged particle is the self-interaction, called the “radiation reaction” or the “radiation damping”. For this reason, the radiation reaction appears in laser electron interactions with an ultra-short pulse laser whose intensity becomes larger than 1022 W/cm2. In the classical theory, it is described by the Lorentz-Abraham-Dirac (LAD) equation. But, this equation has a mathematical difficulty, which we call the “run-away”. Therefore, there are many methods for avoiding this problem. However, Dirac's viewpoint is brilliant, based on the idea of quantum electrodynamics. We propose a new equation of motion in the quantum theory with radiation reaction in this paper.

  19. Poly(1,4-phenyleneazine N,N-dioxide): A recyclable material for a solventless laser-imageable resist process

    SciTech Connect

    Baum, T.H.; Larson, C.E.; Hacker, N.P.

    1994-11-01

    Upon heating under vacuum, poly(1,4-phenyleneazine-N,N-dioxide) depolymerizes to give 1,4-dinitrosobenzene which can be condensed onto a suitable substrate. The nature of the condensate is dependent on the substrate temperature. At temperatures below -110{degrees}C the condensate can be monomeric, at about -50{degrees}C it is a mixture of dimer and oligomers, and at -20{degrees}C it is polymeric. Thick and thin films of the polymer can be rapidly prepared by volatilization of 1,4-dinitrosobenzene from the bulk polymer onto a substrate and allowing the collected condensate to warm to room temperature. The resultant films appear to be stable indefinitely at room temperature and atmospheric pressure yet can be selectively removed from the substrate using a focused visible laser beam. After a suitable image-transfer process, the polymer is removed by heating to 100{degrees}C. The laser imaging, deposition, and final removal of polymer are all nondestructive, thermal processes. Thus if a suitable vacuum chamber equipped with a cooling trap is used for this process, the polymer is 100% recyclable. 14 refs., 6 figs.

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

    NASA Astrophysics Data System (ADS)

    Hawkins, Jan F.; McCauley, Charles T.

    2005-04-01

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

  1. Promising Option for Treatment of Striae Alba: Fractionated Microneedle Radiofrequency in Combination with Fractional Carbon Dioxide Laser

    PubMed Central

    Fatemi Naeini, Farahnaz; Behfar, Shadi; Abtahi-Naeini, Bahareh; Keyvan, Shima; Pourazizi, Mohsen

    2016-01-01

    Background. A consistent treatment has not been proposed for treatment of Striae Alba (SA). The present study was designed to compare the fractionated microneedle radiofrequency (FMR) alone and in combination with fractional carbon dioxide laser (FMR + CO2) in the treatment of SA. Methods. Forty-eight pairs of SA from six patients were selected. Right or left SAs were randomly assigned to one of the treatment groups. The surface area of the SA before and after treatment and clinical improvement using a four-point scale were measured at the baseline, after one and three months. Results. The mean age of the patients was 30.17 ± 5.19 years. The mean difference of the surface area between pre- and posttreatment in the FMR + CO2 group was significantly higher than that in the FMR group (p = 0.003). Clinical improvement scales showed significantly higher improvement in the FMR + CO2 group than in the FMR group in the first and second follow-up (p = 0.002 and 0.004, resp.). There were no major persistence side-effects in both groups. Conclusions. The results showed that FMR + CO2 laser was more effective than FMR alone in the treatment of SA. PMID:27069471

  2. Brain lesion induced by 1319nm laser radiation

    NASA Astrophysics Data System (ADS)

    Yang, Zaifu; Chen, Hongxia; Wang, Jiarui; Chen, Peng; Ma, Ping; Qian, Huanwen

    2010-11-01

    The laser-tissue interaction has not been well defined at the 1319 nm wavelength for brain exposure. The goal of this research effort was to identify the behavioral and histological changes of brain lesion induced by 1319 nm laser. The experiment was performed on China Kunming mice. Unilateral brain lesions were created with a continuous-wave Nd:YAG laser (1319nm). The brain lesions were identified through behavioral observation and histological haematoxylin and eosin (H&E) staining method. The behavior change was observed for a radiant exposure range of 97~773 J/cm2. The histology of the recovery process was identified for radiant exposure of 580 J/cm2. Subjects were sacrificed 1 hour, 1 week, 2 weeks, 3 months, 7 months and 13 months after laser irradiation. Results showed that after laser exposure, behavioral deficits, including kyphosis, tail entasia, or whole body paralysis could be noted right after the animals recovered from anesthesia while gradually disappeared within several days and never recurred again. Histologically, the laser lesion showed a typical architecture dependent on the interval following laser treatment. The central zone of coagulation necrosis is not apparent right after exposure but becomes obvious within several days. The nerotic tissue though may persist for a long time, will finally be completely resorbed. No carbonization granules formed under our exposure condition.

  3. Mechanisms of reduction of tumor recurrence with carbon dioxide laser in experimental mammary tumors.

    PubMed

    Lanzafame, R J; McCormack, C J; Rogers, D W; Naim, J O; Herrera, H R; Hinshaw, J R

    1988-12-01

    This study compares local tumor recurrence after low energy CO2 laser wound sterilization with recurrence after scalpel, laser or electrocautery excision. Wound histologic changes were studied to understand the mechanism of the interaction between the laser and wound. Single implants of R3230AC mammary tumor were grown to an average diameter of 24 millimeters in the mammary ridge of 80 female fisher 344 rats. Rats were anesthesized with pentobarbital and randomized into groups, each with similar tumor size: scalpel (S), laser (L), laser with wound sterilization (LV), scalpel with sterilization (SV) and electrocautery (E). All surgical procedures were performed by the same surgeon with the same technique, with the exception of the instruments used. Tow rats from each group were sacrificed immediately and the wounds examined histologically. The Sharplan 1100 CO2 laser was used with a 125 millimeter hand piece in focus and in continuous wave for groups L and LV. Sterilization in groups LV and SV was performed with 5 millimeter spot size by heating the site gently without causing blanching of tissue. Excision in group E was performed with coagulating current from a monopolar cautery (Valley Lab). Rats were examined periodically for 30 days and those dying during this period were excluded from analysis. The incidence of wound recurrence was eight of 12 in group S; five of eight, L; four of 13, E; three of 12, LV, and two of nine, SV (p less than 0 .05). Histologic changes in the wound demonstrated viable tumor in all groups, with fewer areas present in groups E, SV and LV. Local thermal effects and the noncontact nature of the CO2 laser make it an effective adjunct in reducing local tumor recurrence by enhancing the cytoreductive capability of surgical procedures.

  4. Optical emission of a plasma from low-density targets irradiated with coherence-controllable laser radiation

    NASA Astrophysics Data System (ADS)

    Fronya, A. A.; Borisenko, N. G.; Puzyrev, V. N.; Sahakyan, A. T.; Starodub, A. N.; Yakushev, O. F.

    2017-03-01

    The results of experiments on the interaction of nanosecond laser radiation with low-density volume-structured targets of different density and thickness are reported. The targets were irradiated by laser radiation with controllable coherence. The primary objective was to investigate the effect of target parameters on the characteristics of radiation scattered by the plasma. The spectral characteristics of the radiation scattered by the plasma in the backward direction and in the direction of laser beam propagation were obtained. Also the radiation scattering patterns were recorded.

  5. EFFECT OF LASER LIGHT ON MATTER. LASER PLASMAS: Hardening of aluminium by YAG : Nd laser radiation with an average power of 0.8 kW

    NASA Astrophysics Data System (ADS)

    Kovsh, Ivan B.; Strekalova, M. S.

    1994-02-01

    An investigation is reported of the effects of a surface heat treatment of aluminium by a YAG : Nd laser beam with a power up to 0.8 kW. In particular, a study was made of the influence of the treatment conditions on the microhardness, as well as on the residual stresses and their sign in hardened surface layers of aluminium. The efficiency of aluminium hardening by radiation from a cw YAG : Nd laser was found to be considerably higher than in the case of a cw CO2 laser.

  6. Compression of laser radiation in plasmas using electromagnetic cascading

    NASA Astrophysics Data System (ADS)

    Kalmykov, Serguei

    2005-10-01

    We theoretically suggest an approach to generation of trains of few-femtosecond electromagnetic (EM) pulses in rarefied plasmas. The technique is based on the near-resonant laser beat wave excitation of electron plasma wave (EPW). The EPW modifies the refractive index of plasma thus inducing the periodic phase modulation of the driving laser (the modulation period being equal to the beat period). In spectral terms, the phase modulation is expressed as an EM cascading with the laser bandwidth proportional to the product of the plasma length, laser wavelength, and electron density perturbation in the EPW. In the case of beat wave downshifted from the Langmuir plasma frequency the longer-wavelength spectral components are advanced in time with respect to the shorter-wavelength ones near the center of each laser beat note. The anomalous group velocity dispersion of plasma compresses so chirped beat notes to a few-laser-pulse duration thus creating a train of sharp EM spikes with the beat wave periodicity. Depending on the plasma and laser parameters, chirping and compression can be implemented either concurrently in the same, or sequentially in different plasmas. Evolution of the laser beat wave and electron density perturbations is described in time and in two spatial dimensions (2D) in a weakly relativistic approximation. Using the compression effect, we demonstrate that the relativistic bi-stability regime of the EPW excitation [G. Shvets, Phys. Rev. Lett. 93, 195004 (2004)] can be achieved with the initially sub-threshold beat wave pulse. The effects of 2D evolution such as the relativistic self-focusing and cascade focusing are also addressed. We conjecture that this technique could be used for increasing the local power of sub- picosecond petawatt laser beams.

  7. Laser-plasma SXR/EUV sources: adjustment of radiation parameters for specific applications

    NASA Astrophysics Data System (ADS)

    Bartnik, A.; Fiedorowicz, H.; Fok, T.; Jarocki, R.; Kostecki, J.; Szczurek, A.; Szczurek, M.; Wachulak, P.; Wegrzyński, Ł.

    2014-12-01

    In this work soft X-ray (SXR) and extreme ultraviolet (EUV) laser-produced plasma (LPP) sources employing Nd:YAG laser systems of different parameters are presented. First of them is a 10-Hz EUV source, based on a double-stream gaspuff target, irradiated with the 3-ns/0.8J laser pulse. In the second one a 10 ns/10 J/10 Hz laser system is employed and the third one utilizes the laser system with the pulse shorten to approximately 1 ns. Using various gases in the gas puff targets it is possible to obtain intense radiation in different wavelength ranges. This way intense continuous radiation in a wide spectral range as well as quasi-monochromatic radiation was produced. To obtain high EUV or SXR fluence the radiation was focused using three types of grazing incidence collectors and a multilayer Mo/Si collector. First of them is a multfoil gold plated collector consisted of two orthogonal stacks of ellipsoidal mirrors forming a double-focusing device. The second one is the ellipsoidal collector being part of the axisymmetrical ellipsoidal surface. Third of the collectors is composed of two aligned axisymmetrical paraboloidal mirrors optimized for focusing of SXR radiation. The last collector is an off-axis ellipsoidal multilayer Mo/Si mirror allowing for efficient focusing of the radiation in the spectral region centered at λ = 13.5 ± 0.5 nm. In this paper spectra of unaltered EUV or SXR radiation produced in different LPP source configurations together with spectra and fluence values of focused radiation are presented. Specific configurations of the sources were assigned to various applications.

  8. Infrared radiation and inversion population of CO2 laser levels in Venusian and Martian atmospheres

    NASA Technical Reports Server (NTRS)

    Gordiyets, B. F.; Panchenko, V. Y.

    1983-01-01

    Formation mechanisms of nonequilibrium 10 micron CO2 molecule radiation and the possible existence of a natural laser effect in the upper atmospheres of Venus and Mars are theoretically studied. An analysis is made of the excitation process of CO2 molecule vibrational-band levels (with natural isotropic content) induced by direct solar radiation in bands 10.6, 9.4, 4.3, 2.7 and 2.0 microns. The model of partial vibrational-band temperatures was used in the case. The problem of IR radiation transfer in vibrational-rotational bands was solved in the radiation escape approximation.

  9. Surface modification of polytetrafluoroethylene by excimer-laser radiation

    SciTech Connect

    Nishii, M.; Sugimoto, S.; Shimizu, Y.; Suzuki, N.; Kewanishi, S.; Nagese, T.; Endo, M.; Eguchi, Y.

    1993-12-31

    The adhesive strength of polytetrafluoroethylene (PTFE) films was enhanced remarkably by KrF-laser irradiation in air when a small amount of aromatic polymers such as aromatic polyester, polyetheretherketone and polyimide were blended with PTFE. From the surface analysis of the laser-irradiated PTFE by an X-ray photoelectron spectroscopy and a scanning electron microscopy, it was found that the enhancement in the adhesive properties was attributable to both the chemical effect owing to the formation of the polar groups such as carbonyl group and ethylene linkage and the physical one owing to the formation of the uneveness by the KrF-laser irradiation.

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

    DTIC Science & Technology

    2014-09-26

    reverse if nee~tary an~d Identify by biock number) FIEL GROP SU GR- Laser, Microelectronics , Surface Chemistry 19 ABSTRACT i CoiEIDue on reverset of...direct writing are also being pursued at the Microelectronics Sciences Laboratories at Columbia under separate funding. In addition, extensive interchange...R.M. Osgood and T.F. Deutsch, "Laser-Induced Chemistry for Microelectronics ," Science, Vol.277, pp. 709-714, 1985. R.M. Osgood and H.H. Gilgen, "Laser

  11. Two-wavelength carbon dioxide laser application for in-vitro blood glucose measurements.

    PubMed

    Meinke, Martina; Müller, Gehard; Albrecht, Hansjörg; Antoniou, Christina; Richter, Heike; Lademann, Juergen

    2008-01-01

    To develop a fast and easy clinical method for glucose measurements on whole blood samples, changes in glucose spectra are investigated varying temperature, glucose concentration, and solvent using attenuated total reflection Fourier transform infrared (ATR- FTIR) measurements. The results show a stability of the spectra at different temperatures and wavelength shifts of the absorption bands when water is replaced by blood. Because the ATR measurements are influenced by sedimentation of the red blood cells, a two-wavelength CO2 laser is used to determine the glucose concentration in whole blood samples. For this purpose, the first laser wavelength lambda(1) is tuned to the maximum of the glucose absorption band in blood at 1080 cm(-1), and the second laser wavelength lambda 2 is tuned to 950 cm(-1) for background measurements. The transmitted laser power through the optical cell containing the whole blood sample at lambda 1 and lambda 2 is used to determine the ratio. This signal correlates well with the glucose concentration in the whole blood samples. The CO2 laser measurement is too fast to be influenced by the red blood cell sedimentation, and will be a suitable method for glucose determination in whole blood.

  12. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Effect of pulsed laser target cleaning on ionisation and acceleration of ions in a plasma produced by a femtosecond laser pulse

    NASA Astrophysics Data System (ADS)

    Volkov, Roman V.; Vorobiev, A. A.; Gordienko, Vyacheslav M.; Dzhidzhoev, M. S.; Lachko, I. M.; Mar'in, B. V.; Savel'ev, Andrei B.; Uryupina, D. S.

    2005-10-01

    The impurity layer on the surface of a solid target is shown to exert a significant effect on the characteristics of the ion current of the laser plasma produced under the action of ultrahigh-intensity femtosecond radiation on the surface of this target. The application of pulsed laser cleaning gives rise to an additional high-energy component in the ion spectrum of the target material. It is shown that the ion current parameters of the laser plasma such as the average and highest ion charge, the highest ion energy of the target material, etc., can be controlled by varying the lead time of the cleaning laser radiation.

  13. Highly efficient terahertz radiation from a thin foil irradiated by a high-contrast laser pulse.

    PubMed

    Jin, Z; Zhuo, H B; Nakazawa, T; Shin, J H; Wakamatsu, S; Yugami, N; Hosokai, T; Zou, D B; Yu, M Y; Sheng, Z M; Kodama, R

    2016-09-01

    Radially polarized intense terahertz (THz) radiation behind a thin foil irradiated by ultrahigh-contrast ultrashort relativistic laser pulse is recorded by a single-shot THz time-domain spectroscopy system. As the thickness of the target is reduced from 30 to 2 µm, the duration of the THz emission increases from 5 to over 20 ps and the radiation energy increases dramatically, reaching ∼10.5mJ per pulse, corresponding to a laser-to-THz radiation energy conversion efficiency of 1.7%. The efficient THz emission can be attributed to reflection (deceleration and acceleration) of the laser-driven hot electrons by the target-rear sheath electric field. The experimental results are consistent with that of a simple model as well as particle-in-cell simulation.

  14. Method and apparatus for producing laser radiation following two-photon excitation of a gaseous medium

    DOEpatents

    Bischel, William K. [Menlo Park, CA; Jacobs, Ralph R. [Livermore, CA; Prosnitz, Donald [Hamden, CT; Rhodes, Charles K. [Palo Alto, CA; Kelly, Patrick J. [Fort Lewis, WA

    1979-02-20

    Method and apparatus for producing laser radiation by two-photon optical pumping of an atomic or molecular gaseous medium and subsequent lasing action. A population inversion is created as a result of two-photon absorption of the gaseous species. Stark tuning is utilized, if necessary, in order to tune the two-photon transition into exact resonance. In particular, gaseous ammonia (NH.sub.3) or methyl fluoride (CH.sub.3 F) is optically pumped by a pair of CO.sub.2 lasers to create a population inversion resulting from simultaneous two-photon excitation of a high-lying vibrational state, and laser radiation is produced by stimulated emission of coherent radiation from the inverted level.

  15. Method and apparatus for producing laser radiation following two-photon excitation of a gaseous medium

    DOEpatents

    Bischel, W.K.; Jacobs, R.R.; Prosnitz, D.P.; Rhodes, C.K.; Kelly, P.J.

    1979-02-20

    Method and apparatus are disclosed for producing laser radiation by two-photon optical pumping of an atomic or molecular gaseous medium and subsequent lasing action. A population inversion is created as a result of two-photon absorption of the gaseous species. Stark tuning is utilized, if necessary, in order to tune the two-photon transition into exact resonance. In particular, gaseous ammonia (NH[sub 3]) or methyl fluoride (CH[sub 3]F) is optically pumped by a pair of CO[sub 2] lasers to create a population inversion resulting from simultaneous two-photon excitation of a high-lying vibrational state, and laser radiation is produced by stimulated emission of coherent radiation from the inverted level. 3 figs.

  16. Signatures of quantum radiation reaction in laser-electron-beam collisions

    SciTech Connect

    Wang, H. Y.; Yan, X. Q.; Zepf, M.

    2015-09-15

    Electron dynamics in the collision of an electron beam with a high-intensity focused ultrashort laser pulse are investigated using three-dimensional QED particle-in-cell (PIC) simulations, and the results are compared with those calculated by classical Landau and Lifshitz PIC simulations. Significant differences are observed from the angular dependence of the electron energy distribution patterns for the two different approaches, because photon emission is no longer well approximated by a continuous process in the quantum radiation-dominated regime. The stochastic nature of photon emission results in strong signatures of quantum radiation-reaction effects under certain conditions. We show that the laser spot size and duration greatly influence these signatures due to the competition of QED effects and the ponderomotive force, which is well described in the classical approximation. The clearest signatures of quantum radiation reaction are found in the limit of large laser spots and few cycle pulse durations.

  17. Effects of radiation damping on the dynamics of electrons in ELI intensity laser fields

    NASA Astrophysics Data System (ADS)

    Harvey, Christopher; Marklund, Mattias

    2012-07-01

    An electron in the presence of a high intensity laser field, such as that anticipated at ELI, will be accelerated so strongly that its own radiation emission may significantly affect its motion. This opens up the possibility of testing experimentally the classical theory of radiation reaction in such a context. We therefore explore the effects of radiation damping on the dynamics of electrons in optical laser pulses. In the case of high intensities and high initial electron energies, the trajectories and net energy changes of the electrons are found to be significantly altered. These effects are found to become increasingly significant the closer one gets to a directly head on collision between the laser and electrons.

  18. Spectroscopic support of laser remote sensing of the sulfur dioxide gas in the jet of engine exhaust gases

    NASA Astrophysics Data System (ADS)

    Voitsekhovskaya, O. K.; Kashirskii, D. E.; Egorov, O. V.

    2013-09-01

    The feasibility of SO2 registration in the plume of a jet engine as one of the methods of monitoring of its operation quality is investigated. Spectral characteristics are calculated using the line by line method, information-computing complex TRAVA developed by the authors, and the compiled spectroscopic database on high-temperature SO2. Unlike the HITRAN database, the original spectroscopic data possess predictability up to T = 1500 K. It is established that in case of active SO2 detection using a CO laser, the laser line corresponding to the 32-31 Р5 transition is promising for temperatures T = 300-1100 K. In addition, the most suitable range of the spectrum for passive sensing of hot SO2 in the engine plume - 1330.0-1331.6 cm-1 - is established in which the useful signal level exceeds background radiation for a minimum SO2 concentration (5 ppm).

  19. Oxygen assisted interconnection of silver nanoparticles with femtosecond laser radiation

    SciTech Connect

    Huang, H.; Zhou, Y.; Duley, W. W.

    2015-12-14

    Ablation of silver (Ag) nanoparticles in the direction of laser polarization is achieved by utilizing femtosecond laser irradiation in air at laser fluence ranging from ∼2 mJ/cm{sup 2} to ∼14 mJ/cm{sup 2}. This directional ablation is attributed to localized surface plasmon induced localized electric field enhancement. Scanning electron microscopy observations of the irradiated particles in different gases and at different pressures indicate that the ablation is further enhanced by oxygen in the air. This may be due to the external heating via the reactions of its dissociation product, atomic oxygen, with the surface of Ag particles, while the ablated Ag is not oxidized. Further experimental observations show that the ablated material re-deposits near the irradiated particles and results in the extension of the particles in laser polarization direction, facilitating the interconnection of two well-separated nanoparticles.

  20. The effect of carbon dioxide laser on wound contraction and epithelial regeneration in rabbits.

    PubMed

    Jarmuske, M B; Stranc, M F; Stranc, L C

    1990-01-01

    This study was undertaken to compare objectively healing rates (in rabbits) of wounds caused by CO2 laser with those caused by scalpel. The rates of contraction and epithelialisation of standard wounds were determined with daily measurement of wound area from the time of wounding until the wound had healed. Our results demonstrate significant delays in both wound contraction (p = 0.0001) and epithelialisation (p = 0.0001) for CO2 laser-created wounds when compared to those seen in scalpel-created wounds. Normal epithelial regenerative capacities were demonstrated in the laser group despite the slow onset of epithelial migration. The appearance of the healed areas appeared comparable for both modalities.

  1. Effects of Nd:YAG (532 nm) laser radiation on `clean' cotton

    NASA Astrophysics Data System (ADS)

    Bloisi, F.; Vicari, L.; Barone, A. C.; Martuscelli, E.; Gentile, G.; Polcaro, C.

    The use of pulsed laser radiation in order to remove small particles from a substrate has gained a growing interest in the last decade, finding applications in several fields ranging from the microcircuits industry to cultural heritage restoration and conservation. The application of such a technique requires the knowledge of the correct laser irradiation parameters to be used in order to obtain a desired result avoiding substrate damage. In this paper we have studied the effect of frequency-doubled (532 nm) Nd:YAG laser radiation on clean cotton samples. We have observed that `yellowing' is present even at low fluences. This suggests that less invasive laser assisted particle removal techniques, some of which have already been proposed by different authors, must be considered.

  2. Interaction of near-IR laser radiation with plasma of a continuous optical discharge

    NASA Astrophysics Data System (ADS)

    Zimakov, V. P.; Kuznetsov, V. A.; Solovyov, N. G.; Shemyakin, A. N.; Shilov, A. O.; Yakimov, M. Yu.

    2016-01-01

    The interaction of 1.07-μm laser radiation with plasma of a continuous optical discharge (COD) in xenon and argon at a pressure of p = 3-25 bar and temperature of T = 15 kK has been studied. The threshold power required to sustain COD is found to decrease with increasing gas pressure to P t < 30 W in xenon at p > 20 bar and to P t < 350 W in argon at p > 15 bar. This effect is explained by an increase in the coefficient of laser radiation absorption to 20-25 cm-1 in Xe and 1-2 cm-1 in Ar due to electronic transitions between the broadened excited atomic levels. The COD characteristics also depend on the laser beam refraction in plasma. This effect can be partially compensated by a tighter focusing of the laser beam. COD is applied as a broadband light source with a high spectral brightness.

  3. Quantum mechanical theory of collisional ionization in the presence of intense laser radiation

    NASA Technical Reports Server (NTRS)

    Bellum, J. C.; George, T. F.

    1978-01-01

    The paper presents a quantum mechanical formalism for treating ionizing collisions occurring in the presence of an intense laser field. Both the intense laser radiation and the internal electronic continuum states associated with the emitted electrons are rigorously taken into account by combining discretization techniques with expansions in terms of electronic-field representations for the quasi-molecule-plus-photon system. The procedure leads to a coupled-channel description of the heavy-particle dynamics which involves effective electronic-field potential surfaces and continua. It is suggested that laser-influenced ionizing collisions can be studied to verify the effects of intense laser radiation on inelastic collisional processes. Calculation procedures for electronic transition dipole matrix elements between discrete and continuum electronic states are outlined.

  4. Crystallization of hydrogenated amorphous silicon films by exposure to femtosecond pulsed laser radiation

    SciTech Connect

    Volodin, V. A.; Kachko, A. S.

    2011-02-15

    To crystallize hydrogenated amorphous silicon films on glass substrates, pulsed Ti-sapphire laser radiation is used, with a pulse duration less than 30 fs. The initial films are grown by plasma-enhanced chemical-vapor deposition at the temperatures 200 and 250 Degree-Sign C. The structural properties of the initial films and films treated with laser radiation pulses are studied by Raman spectroscopy. The conditions for complete crystallization of the films grown on glass substrates to thicknesses of up to 100 nm and hydrogen content of up to 20 at % are established. The conditions provide the fabrication of highly homogeneous films by scanning laser treatments. It is found that, if the hydrogen content in the film is 30-40 at %, the crystallization is an inhomogeneous process and laser ablation is observed in some areas of the films.

  5. Strong terahertz radiation from relativistic laser interaction with solid density plasmas

    NASA Astrophysics Data System (ADS)

    Li, Y. T.; Li, C.; Zhou, M. L.; Wang, W. M.; Du, F.; Ding, W. J.; Lin, X. X.; Liu, F.; Sheng, Z. M.; Peng, X. Y.; Chen, L. M.; Ma, J. L.; Lu, X.; Wang, Z. H.; Wei, Z. Y.; Zhang, J.

    2012-06-01

    We report a plasma-based strong THz source generated in intense laser-solid interactions at relativistic intensities >1018 W/cm2. Energies up to 50 μJ/sr per THz pulse is observed when the laser pulses are incident onto a copper foil at 67.5°. The temporal properties of the THz radiation are measured by a single shot, electro-optic sampling method with a chirped laser pulse. The THz radiation is attributed to the self-organized transient fast electron currents formed along the target surface. Such a source allows potential applications in THz nonlinear physics and provides a diagnostic of transient currents generated in intense laser-solid interactions.

  6. Reduction of collisional-radiative models for laser-produced argon plasmas

    NASA Astrophysics Data System (ADS)

    Abrantes, Richard June; Karagozian, Ann; Le, Hai

    2016-10-01

    The formation of a laser-induced plasma involves a variety of physical phenomena stemming from the laser-plasma interaction. A thorough understanding of these processes encourages improvement and innovation for many applications. In this work, we aim to computationally reduce a previously-developed collisional-radiative (CR) model constructed from the LANL database, which includes all of the relevant collisional and radiative processes for all the ionic stages of argon. The laser is coupled to the plasma via multiphoton ionization and inverse Bremsstrahlung, processes important for electron production and heating. The use of the CR model allows us to identify dominant mechanisms responsible for initial breakdown of the gas and thermal equilibriation processes. The results are compared with experimental data from laser-induced breakdown experiments. Research supported by the AFOSR.

  7. Absorption of Deuterium Fluoride Laser Radiation by the Atmosphere

    DTIC Science & Technology

    1976-04-01

    spectroscopy technique was used to determine the frequencies of the 3-2 P(7) and 2-1 P(10) lines by measuring their separation from N2O absorption lines...19. KEY WORDS ( Continue on reverse aide il necessary and (den(//y by bloc* number) Absorption DF laser Laser Propagation Molecular... Spectroscopy HDO Water Vapor Methane Nitrous Oxide Spectra Atmosphere ■jr—.„sTRACT rConllnue on reverse side 1/necessary and Identity by block number

  8. Research on the Ocular Effects of Laser Radiation. Executive Summary

    DTIC Science & Technology

    1988-09-01

    of the overall effect of the laser insult on macular function. Experiments were conducted while the animals were maintained at a surgical plane of...apparent spreading of blood away from lesion site). One exposure depositing 40 #J in the para- macular region resulted in a spreading hemorrhage into...without the complication of additional retinal pathology, but also of off-axis (para- macular ) laser lesions on central retinal function, we examined the

  9. Base-Level Management of Laser Radiation Protection Program

    DTIC Science & Technology

    1992-02-01

    lasers exempt from 21 CFR, Subchapter J, under FDA Exemption No 76 EL-01 DoD. Currently under revision. E. Practical comments on laser safety. Despite the...transition from Q, to Qm must be sufficiently fast and energy level Qm must be relatively stable. Under these conditions, the population of atoms at energy...low pressure , the atoms or molecules are in constant random motion. The frequency of the emission is subject to variations caused by Doppler

  10. Effects of Growth Temperature on Epitaxial Thin Films of Vanadium Dioxide Grown by Pulsed Laser Deposition

    SciTech Connect

    Nag, Joyeeta; HaglundJr., Richard F; Payzant, E Andrew

    2011-01-01

    Stoichiometric vanadium dioxide in all of its bulk, thin film and nanostructured forms exhibits an insulator-to-metal transition (IMT) accompanied by structural change, induced by various physical and chemical stimuli such as temperature, ultrashort light pulses, electric field, doping or strain. In these applications, the optical qualities of the films are of paramount importance, but are often highly variable depending on fabrication procedure. We have grown epitaxial films of vanadium dioxide on c-plane (0001) of sapphire using two different procedures involving room temperature growth followed by annealing and direct high temperature growth. Strain at the interface of the substrate and the film due to growth at different temperatures leads to significant differences in morphologies and phase transition characteristics. We present a comparative study of the morphologies and switching characteristics of the two films and conclude that contrary to conventional wisdom, the room-temperature grown films have smoother, more continuous morphologies and better switching performance. Our observation is supported by theoretical and experimental studies of epitaxial growth of semiconductors.

  11. A semiconductor injection-switched high-pressure sub-10-picosecond carbon dioxide laser amplifier

    NASA Astrophysics Data System (ADS)

    Hughes, Michael Kon Yew

    A multiatmospheric-pressure-broadened CO2 laser amplifier was constructed to amplify sub-10-picosecond pulses generated with semiconductor switching. High-intensity, mid-infrared, amplified pulses have many applications: especially in fields such as non-linear optics, laser-plasma interaction, and laser particle acceleration. The injected pulses are produced by exciting GaAs (or an engineered, fast-recombination time semiconductor) with an ultrafast visible laser pulse to induce transient free carriers with sufficient density to reflect a co-incident hybrid-CO2 laser pulse. The short pulse is injected directly into the regenerative amplifier cavity from an intra-cavity semiconductor switch. The CO2-gas-mix amplifier is operated at 1.24 MPa which is sufficient to collisionally broaden the individual rotational spectral lines so that they merge to produce a gain spectrum wide enough to support pulses less than 10 ps long. After sufficient amplification, the pulse is switched out with another semiconductor switch pumped with a synchronized visible-laser pulse. This system is demonstrated and analysed spectrally and temporally. The pulse-train spectral analysis is done for a GaAs-GaAs double-switch arrangement using a standard spectrometer and two HgCdTe detectors; one of which is used for a reference signal. An infrared autocorrelator was designed and constructed to temporally analyse the pulse trains emerging from the amplifier. Interpretation of the results was aided by the development of a computer model for short-pulse amplification which incorporated saturation effects, rotational- and vibrational-mode energy redistribution between pulse round trips, and the gain enhancement due to one sequence band. The results show that a sub-10-picosecond pulse is injected into the cavity and that it is amplified with some trailing pulses at 18 ps intervals generated by coherent effects. The energy level reached, estimated through modelling, was >100 mJ/cm2.

  12. CONTROL OF LASER RADIATION PARAMETERS: Reduction of wavefront aberrations and laser radiation divergence of the 'Luch' facility with the help of an adaptive system

    NASA Astrophysics Data System (ADS)

    Voronich, Ivan N.; Garanin, Sergey G.; Zaretskii, Aleksei I.; Zimalin, B. G.; Kirillov, G. A.; Kulikov, S. M.; Manachinckii, A. N.; Murugov, Vasilii M.; Ogorodnikov, A. V.; Smyshlyaev, S. P.; Sukharev, Stanislav A.

    2005-02-01

    An adaptive system for the compensation of static and thermally induced wavefront aberrations of the amplification path of the 'Luch' laser facility is described. This system provided the reduction of the amplitude A of wavefront aberrations of high-power radiation and the standard deviation σ by a factor of ~3: from A = 9.6 μm, σ = 2.4 μm to A = 3.2 μm, σ = 0.6 μm, which decreased the radiation divergence by half.

  13. Onychoplasty with carbon dioxide laser matrixectomy for treatment of ingrown toenails.

    PubMed

    Farley-Sakevich, Tara; Grady, John F; Zager, Emil; Axe, Timothy M

    2005-01-01

    Ingrown toenails are one of the most common pathologic conditions encountered in podiatric medical practice. Many methods of treatment for ingrown toenails have been used and studied, including chemical matrixectomies, surgical approaches, and CO(2) laser ablation. This study is a retrospective review of a new technique that consists of resection of the involved nail matrix using a No. 15 blade and controlled cauterization using a CO(2) laser. The technique was performed on 381 painful ingrown toenails, and all of the patients were followed up postoperatively for an average of 34 months. The results showed minimal pain, a low recurrence rate, rapid return to activity, and good cosmesis.

  14. Ultra-broadband hybrid infrared laser system

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    A hybrid IR laser system consisting of molecular gas lasers with frequency conversion of laser radiation in a solid-state converter (nonlinear crystal) was developed. One of these gas lasers is a carbon monoxide laser operating in multi-line or single-line mode. Another one is a carbon dioxide laser operating in multi-line mode. The two lasers operate under Q-switching with a joint rotating mirror. Due to sum- and difference-frequency generation in nonlinear crystals, the laser system emits within wavelength range from 2.5 to 16.6 μm. The laser system emitting radiation over such an extremely wide wavelength range (2.7 octaves) is of interest for remote sensing and other applications connected with laser beam propagation in the atmosphere.

  15. Laser-IORT: a laser-driven source of relativistic electrons suitable for Intra-Operative Radiation Therapy of tumors

    SciTech Connect

    Gamucci, A.; Giulietti, A.; Gizzi, L. A.; Labate, L.; Bourgeois, N.; Marques, J. R.; Ceccotti, T.; Dobosz, S.; D'Oliveira, P.; Monot, P.; Popescu, H.; Reau, F.; Martin, Ph.; Galy, J.; Giulietti, D.; Hamilton, D. J.; Sarri, G.

    2010-02-02

    In a recent experiment [1] a high efficiency regime of stable electron acceleration to kinetic energies ranging from 10 to 40 MeV has been achieved. The main parameters of the electron bunches are comparable with those of bunches provided by commercial Radio-Frequency based Linacs currently used in Hospitals for Intra-Operative Radiation Therapy (IORT). IORT is an emerging technique applied in operating theaters during the surgical treatment of tumors. Performances and structure of a potential laser-driven Hospital accelerator are compared in detail with the ones of several commercial devices. A number of possible advantages of the laser based technique are also discussed.

  16. The absorption and radiation of a tungsten plasma plume during nanosecond laser ablation

    NASA Astrophysics Data System (ADS)

    Moscicki, T.; Hoffman, J.; Chrzanowska, J.

    2015-10-01

    In this paper, the effect of absorption of the laser beam and subsequent radiation on the dynamics of a tungsten plasma plume during pulsed laser ablation is analyzed. Different laser wavelengths are taken into consideration. The absorption and emission coefficients of tungsten plasma in a pressure range of 0.1-100 MPa and temperature up to 70 000 K are presented. The shielding effects due to the absorption and radiation of plasma may have an impact on the course of ablation. The numerical model that describes the tungsten target heating and the formation of the plasma and its expansion were made for 355 nm and 1064 nm wavelengths of a Nd:YAG laser. The laser beam with a Gaussian profile was focused to a spot size of 0.055 mm2 with a power density of 1 × 109 W/cm2 (10 ns full width half maximum pulse duration). The plasma expands into air at ambient pressure of 1 mPa. The use of the shorter wavelength causes faster heating of the target, thus the higher ablation rate. The consequences of a higher ablation rate are slower expansion and smaller dimensions of the plasma plume. The higher plasma temperature in the case of 1064 nm is due to the lower density and lower plasma radiation. In the initial phase of propagation of the plasma plume, when both the temperature and pressure are very high, the dominant radiation is emission due to photo-recombination. However, for a 1064 nm laser wavelength after 100 ns of plasma expansion, the radiation of the spectral lines is up to 46.5% of the total plasma radiation and should not be neglected.

  17. The absorption and radiation of a tungsten plasma plume during nanosecond laser ablation

    SciTech Connect

    Moscicki, T. Hoffman, J.; Chrzanowska, J.

    2015-10-15

    In this paper, the effect of absorption of the laser beam and subsequent radiation on the dynamics of a tungsten plasma plume during pulsed laser ablation is analyzed. Different laser wavelengths are taken into consideration. The absorption and emission coefficients of tungsten plasma in a pressure range of 0.1–100 MPa and temperature up to 70 000 K are presented. The shielding effects due to the absorption and radiation of plasma may have an impact on the course of ablation. The numerical model that describes the tungsten target heating and the formation of the plasma and its expansion were made for 355 nm and 1064 nm wavelengths of a Nd:YAG laser. The laser beam with a Gaussian profile was focused to a spot size of 0.055 mm{sup 2} with a power density of 1 × 10{sup 9 }W/cm{sup 2} (10 ns full width half maximum pulse duration). The plasma expands into air at ambient pressure of 1 mPa. The use of the shorter wavelength causes faster heating of the target, thus the higher ablation rate. The consequences of a higher ablation rate are slower expansion and smaller dimensions of the plasma plume. The higher plasma temperature in the case of 1064 nm is due to the lower density and lower plasma radiation. In the initial phase of propagation of the plasma plume, when both the temperature and pressure are very high, the dominant radiation is emission due to photo-recombination. However, for a 1064 nm laser wavelength after 100 ns of plasma expansion, the radiation of the spectral lines is up to 46.5% of the total plasma radiation and should not be neglected.

  18. The effect of near-infrared MLS laser radiation on cell membrane structure and radical generation.

    PubMed

    Kujawa, Jolanta; Pasternak, Kamila; Zavodnik, Ilya; Irzmański, Robert; Wróbel, Dominika; Bryszewska, Maria

    2014-09-01

    The therapeutic effects of low-power laser radiation of different wavelengths and light doses are well known, but the biochemical mechanism of the interaction of laser light with living cells is not fully understood. We have investigated the effect of MLS (Multiwave Locked System) laser near-infrared irradiation on cell membrane structure, functional properties, and free radical generation using human red blood cells and breast cancer MCF-4 cells. The cells were irradiated with low-intensity MLS near-infrared (simultaneously 808 nm, continuous emission and 905 nm, pulse emission, pulse-wave frequency, 1,000 or 2,000 Hz) laser light at light doses from 0 to 15 J (average power density 212.5 mW/cm(2), spot size was 3.18 cm(2)) at 22 °C, the activity membrane bound acetylcholinesterase, cell stability, anti-oxidative activity, and free radical generation were the parameters used in characterizing the structural and functional changes of the cell. Near-infrared low-intensity laser radiation changed the acetylcholinesterase activity of the red blood cell membrane in a dose-dependent manner: There was a considerable increase of maximal enzymatic rate and Michaelis constant due to changes in the membrane structure. Integral parameters such as erythrocyte stability, membrane lipid peroxidation, or methemoglobin levels remained unchanged. Anti-oxidative capacity of the red blood cells increased after MLS laser irradiation. This irradiation induced a time-dependent increase in free radical generation in MCF-4 cells. Low-intensity near-infrared MLS laser radiation induces free radical generation and changes enzymatic and anti-oxidative activities of cellular components. Free radical generation may be the mechanism of the biomodulative effect of laser radiation.

  19. Collisionless dissociation and isotopic enrichment of SF6 using high-powered CO2 laser radiation

    NASA Technical Reports Server (NTRS)

    Gower, M. C.; Billman, K. W.

    1977-01-01

    Dissociation of S-32F6 and the resultant isotopic enrichment of S-34F6 using high-powered CO2 laser radiation has been studied with higher experimental sensitivity than previously reported. Enrichment factors have been measured as a function of laser pulse number, wavelength, energy and time duration. A geometry independent dissociation cross section is introduced and measured values are presented. Threshold energy densities, below which no dissociation was observed, were also determined.

  20. Analysing radiative and non-radiative recombination in InAs QDs on Si for integrated laser applications

    NASA Astrophysics Data System (ADS)

    Orchard, Jonathan R.; Woodhead, Chris; Shutts, Samuel; Wu, Jiang; Sobiesierski, Angela; Young, Rob J.; Beanland, Richard; Liu, Huiyun; Smowton, Peter M.; Mowbray, David J.

    2016-03-01

    Three InAs quantum dot (QD) samples with dislocation filter layers (DFLs) are grown on Si substrates with and without in-situ annealing. Comparison is made to a similar structure grown on a GaAs substrate. The three Si grown samples have different dislocation densities in their active region as revealed by structural studies. By determining the integrated emission as a function of laser power it is possible to determine the power dependence of the radiative efficiency and compare this across the four samples. The radiative efficiency increases with decreasing dislocation density; this also results in a decrease in the temperature quenching of the PL. A laser structures grown on Si and implementing the same optimum DFL and annealing procedure exhibits a greater than 3 fold reduction in threshold current as well as a two fold increase in slope efficiency in comparison to a device in which no annealing is applied.

  1. Influence of MLS laser radiation on erythrocyte membrane fluidity and secondary structure of human serum albumin.

    PubMed

    Pasternak, Kamila; Nowacka, Olga; Wróbel, Dominika; Pieszyński, Ireneusz; Bryszewska, Maria; Kujawa, Jolanta

    2014-03-01

    The biostimulating activity of low level laser radiation of various wavelengths and energy doses is widely documented in the literature, but the mechanisms of the intracellular reactions involved are not precisely known. The aim of this paper is to evaluate the influence of low level laser radiation from an multiwave locked system (MLS) of two wavelengths (wavelength = 808 nm in continuous emission and 905 nm in pulsed emission) on the human erythrocyte membrane and on the secondary structure of human serum albumin (HSA). Human erythrocytes membranes and HSA were irradiated with laser light of low intensity with surface energy density ranging from 0.46 to 4.9 J cm(-2) and surface energy power density 195 mW cm(-2) (1,000 Hz) and 230 mW cm(-2) (2,000 Hz). Structural and functional changes in the erythrocyte membrane were characterized by its fluidity, while changes in the protein were monitored by its secondary structure. Dose-dependent changes in erythrocyte membrane fluidity were induced by near-infrared laser radiation. Slight changes in the secondary structure of HSA were also noted. MLS laser radiation influences the structure and function of the human erythrocyte membrane resulting in a change in fluidity.

  2. Assessment and Mitigation of Radiation, EMP, Debris & Shrapnel Impacts at Megajoule-Class Laser Facilities

    SciTech Connect

    Eder, D C; Anderson, R W; Bailey, D S; Bell, P; Benson, D J; Bertozzi, A L; Bittle, W; Bradley, D; Brown, C G; Clancy, T J; Chen, H; Chevalier, J M; Combis, P; Dauffy, L; Debonnel, C S; Eckart, M J; Fisher, A C; Geille, A; Glebov, V Y; Holder, J; Jadaud, J P; Jones, O; Kaiser, T B; Kalantar, D; Khater, H; Kimbrough, J; Koniges, A E; Landen, O L; MacGowan, B J; Masters, N D; MacPhee, A; Maddox, B R; Meyers, M; Osher, S; Prasad, R; Raffestin, D; Raimbourg, J; Rekow, V; Sangster, C; Song, P; Stoeckl, C; Stowell, M L; Teran, J M; Throop, A; Tommasini, R; Vierne, J; White, D; Whitman, P

    2009-10-05

    The generation of neutron/gamma radiation, electromagnetic pulses (EMP), debris and shrapnel at mega-Joule class laser facilities (NIF and LMJ) impacts experiments conducted at these facilities. The complex 3D numerical codes used to assess these impacts range from an established code that required minor modifications (MCNP - calculates neutron and gamma radiation levels in complex geometries), through a code that required significant modifications to treat new phenomena (EMSolve - calculates EMP from electrons escaping from laser targets), to a new code, ALE-AMR, that is being developed through a joint collaboration between LLNL, CEA, and UC (UCSD, UCLA, and LBL) for debris and shrapnel modelling.

  3. Acousto-optic diffraction of multicolour Ar-laser radiation in crystalline quartz

    SciTech Connect

    Kotov, V M; Averin, S V; Voronko, A I; Kuznetsov, P I; Tikhomirov, S A; Shkerdin, G N; Bulyuk, A N

    2015-10-31

    We have studied acousto-optic Bragg diffraction of multicolour radiation, generated by an Ar laser in the blue-green region of the spectrum, on an acoustic wave propagating in crystalline quartz. It is shown that crystalline quartz significantly exceeds commonly used paratellurite in terms of phase matching of optical beams with a single acoustic wave. We have performed experiments on pulse modulation of Ar-laser radiation. It is shown that distortions introduced into optical pulses are substantially less when use is made of a quartz crystal rather than paratellurite. (acoustooptics)

  4. Exposure to laser radiation for creation of metal materials nanoporous structures

    NASA Astrophysics Data System (ADS)

    Murzin, Serguei P.

    2013-06-01

    Exposure to laser radiation for creation of nanoporous structures in the Cu-Zn alloy was investigated. It was established that exposure to laser pulse-periodic radiation with pulse repetition rate up to 5000 Hz makes it possible to form a nanoporous structure in the near-surface layer. The conditions of increase of area depth of such structures formation up to 40-45 μm were ascertained. The temperature and speed conditions which provide predominant channel-type nanopores formation with width of about 100 nm forming a nanoporous net were determined. This patented technology is a perspective for production of catalysts and microfiltration membranes.

  5. Mechanisms of interaction of laser radiation with ocular tissues: implications for human exposure limits

    NASA Astrophysics Data System (ADS)

    Sliney, D. H.

    1981-12-01

    Many investigations of laser injury to the eye have been carried out over the past 15 years in order to set standards for safe exposure of the human eye to laser radiation. A review of this extensive body of mainly experimental data suggests that there are at least three dominant mechanisms of injury which are well accepted. However, other effects cannot be ruled out. In particular, several results suggest that the time evolution of injury and repair processes as well as the physical aspects of the interaction of biological tissue with optical radiation must be considered.

  6. Stereological study of the capillaries in the thyroid gland after IR laser radiation

    NASA Astrophysics Data System (ADS)

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

    1994-02-01

    We have planned a stereological ultrastructural study of capillaries in the thyroid gland treated with IR laser radiation and quantified 1 day after the last treatment. Wistar rats, 50 days old, were irradiated with IR laser radiation. The rats were perfused with 2.5 percent glutaraldehyde in 0.1 M phosphate buffer (ph equals 7.4). The pieces obtained after sectioning the thyroid gland were placed immediately into the same fixative. A stereological study of the thyroid capillaries was carried out. This analysis revealed an increase of luminal area in irradiated capillaries.

  7. UV and IR laser radiation's interaction with metal film and teflon surfaces

    NASA Astrophysics Data System (ADS)

    Fedenev, A. V.; Alekseev, S. B.; Goncharenko, I. M.; Koval', N. N.; Lipatov, E. I.; Orlovskii, V. M.; Shulepov, M. A.; Tarasenko, V. F.

    2003-04-01

    The interaction of Xe ([lambda] [similar] 1.73 [mu]m) and XeCl (0.308 [mu]m) laser radiation with surfaces of metal and TiN-ceramic coatings on glass and steel substrates has been studied. Correlation between parameters of surface erosion versus laser-specific energy was investigated. Monitoring of laser-induced erosion on smooth polished surfaces was performed using optical microscopy. The correlation has been revealed between characteristic zones of thin coatings damaged by irradiation and energy distribution over the laser beam cross section allowing evaluation of defects and adhesion of coatings. The interaction of pulsed periodical CO2 ([lambda] [similar] 10.6 [mu]m), and Xe ([lambda] [similar] 1.73 [mu]m) laser radiation with surfaces of teflon (polytetrafluoroethylene—PTFE) has been studied. Monitoring of erosion track on surfaces was performed through optical microscopy. It has been shown that at pulsed periodical CO2-radiation interaction with teflon the sputtering of polymer with formation of submicron-size particles occurs. Dependencies of particle sizes, form, and sputtering velocity on laser pulse duration and target temperature have been obtained.

  8. Research on a laser ultrasound method for testing the quality of a nuclear radiation protection structure

    NASA Astrophysics Data System (ADS)

    Zhang, Kuanshuang; Zhou, Zhenggan; Ma, Liyin

    2017-02-01

    Laser ultrasonics has been investigated for inspecting the quality of a nuclear radiation protection structure. A possibility is proposed to improve the signal to noise ratio (SNR) of a laser ultrasonic inspection system. Then, a nuclear radiation protection structure composed of an AISI 1045 steel sheet connected with a lead alloy sheet by using an epoxy resin adhesive was manufactured with simulated defects. A non-contact laser ultrasonic inspection system, where the measured signals were filtered using a wavelet threshold de-noising method, was established to conduct a series of experiments. The proposed signal processing method can significantly improve the SNR of measured laser ultrasound signals on a rough solid surface. Compared with the SNR of original ultrasonic signals measured in transmission and reflection, the SNR of processed transmitted and reflected signals is improved by 13.8 and 16.6 dB, respectively. Moreover, laser ultrasonic C-scans based on the transmission and pulse-echo method can detect the simulated de-bonding defects, and the relative deviation between the measured sizes and design values is below 9%. Therefore, the laser ultrasonic method combined with effective signal processing can achieve the quantitative characterization of de-bonding defects in nuclear radiation protection structures.

  9. In vivo study of necrosis on the liver tissue of Wistar rats: a combination of photodynamic therapy and carbon dioxide laser ablation

    NASA Astrophysics Data System (ADS)

    Rego, R. F.; Nicolodelli, G.; Araujo, M. T.; Tirapelli, L. F.; Araujo-Moreira, F. M.; Bagnato, V. S.

    2013-07-01

    Photodynamic therapy (PDT) is known to be limited to applications in large volume tumors due to its limited penetration. Therefore, a combination of PDT and carbon dioxide (CO2) laser ablation may constitute a potential protocol to destroy bulk tumors because it involves an association of these two techniques allowing the removal of visible lesions with a high selectivity of destruction of remnant tumors. The main aim of this study is to investigate the most appropriate procedure to combine use of a CO2 laser and PDT on livers of healthy rats, and to analyze different techniques of this treatment using three types of photosensitizers (PSs). Forty eight animals were separated to form six groups: (1) only CO2 laser ablation, (2) drug and CO2 laser ablation, (3) only PDT, (4) drug and light (PDT) followed by CO2 laser ablation, (5) ablated with CO2 laser followed by PDT, and (6) drug followed by CO2 laser ablation and light. For each group, three types of photosensitization were used: topical 5-aminolevulinic acid (ALA), intravenous ALA and intravenous Photogem®. Thirty hours after the treatments, the animals were sacrificed and the livers removed. The depth of necrosis was analyzed and measured, considering microscopic and macroscopic aspects. The results show that the effects of the PDT were considerably enhanced when combined with CO2 laser ablation, especially when the PDT was performed before the CO2 laser ablation.

  10. Experimental comparison of laser energy losses in high-quality laser-oxygen cutting of low-carbon steel using radiation from fibre and CO{sub 2} lasers

    SciTech Connect

    Golyshev, A A; Malikov, A G; Orishich, A M; Shulyat'ev, V B

    2015-09-30

    We report a comparative experimental study of laseroxygen cutting of low-carbon steel using a fibre laser with a wavelength of 1.07 μm and a CO{sub 2} laser with a wavelength of 10.6 μm at the sheet thickness of 3 – 16 mm. For the two lasers we have measured the dependence of the cutting speed on the radiation power and determined the cutting speed at which the surface roughness is minimal. The coefficient of laser radiation absorption in the laser cutting process is measured for these lasers at different values of the cutting speed and radiation power. It is found that the minimal roughness of the cut surface is reached at the absorbed laser energy per unit volume of the removed material, equal to 11 – 13 J mm{sup -3}; this value is the same for the two lasers and does not depend on the sheet thickness. (laser technologies)

  11. CONTROL OF LASER RADIATION PARAMETERS: Generation of polarisation-nonuniform modes in a high-power CO2 laser

    NASA Astrophysics Data System (ADS)

    Niz'ev, Vladimir G.; Yakunin, V. P.; Turkin, N. G.

    2009-06-01

    A method describing radially and azimuthally polarised laser modes is presented, which is devoid of intrinsic contradictions and unjustified restrictions. The solutions of the wave equation found in the paper satisfy Maxwell's equation bigtriangledownE = 0. This allowed the calculation of all the components of the fields of such modes, including the longitudinal one. Expressions for tight focusing of radially and azimuthally polarised modes are obtained in the Debye approximation. The methods of intracavity generation of such modes in a high-power industrial CO2 laser are experimentally realised and methods of mutual transformation of these modes outside the cavity are developed. The intracavity generation of azimuthally polarised modes was achieved by using as a rear highly reflecting mirror either V-shaped axicons or metal diffraction mirrors with the relief period comparable to the wavelength. Radially polarised radiation was generated by using diffraction mirrors with the relief period of the order of two wavelengths. The polarisation-nonuniform TEM01* and TEM11* modes of power up to 1.8 kW are generated for the first time. In this case, the degree of polarisation was close to 100% within the entire radiation power range both in the near- and far-field zones. By using two half-wave phase shifters, the azimuthally polarised radiation is transformed to radially polarised radiation and vice versa, the energy efficiency of this transformation being 92%. These results open up the possibility for industrial applications of such radiation.

  12. Radiative reverse shock laser experiments relevant to accretion processes in cataclysmic variables

    SciTech Connect

    Krauland, C. M.; Drake, R. P.; Kuranz, C. C.; Sweeney, R.; Grosskopf, M.; Klein, S.; Gillespie, R.; Keiter, P. A.; Loupias, B.; Falize, E.

    2013-05-15

    We discuss the production of radiative reverse shocks in experiments at the Omega-60 laser facility. The ability of this high-intensity laser to impart large energy densities on micron-thin foils makes it feasible to create supersonic plasma flows. Obtaining a radiative reverse shock in the laboratory requires a sufficiently fast flow (∼100 km/s) of a material whose opacity is large enough to produce energetically significant emission from experimentally achievable shocked layers. The reverse shock forms in the flow once it is impeded. This paper presents the first radiographic data of normal incidence, reverse shockwaves. These experiments are primarily motivated by the contribution of radiative reverse shock waves to the evolving dynamics of the cataclysmic variable (CV) system in which they reside. We show similarity properties to suggest that the experimental production of radiative reserve shocks in the laboratory may be scalable to such astrophysical systems.

  13. Study of shockwave method for diagnosing the radiation fields of laser-driven gold hohlraums

    NASA Astrophysics Data System (ADS)

    Li, Yongsheng; Lan, Ke; Huo, Wenyi; Lai, Dongxian; Gao, Yaoming; Pei, Wenbing

    2013-11-01

    Besides the routinely used broad-band x-ray spectrometer (Dante or SXS), ablative shock-wave method is often used to diagnose the radiation fields of laser-driven Hohlraums. The x-ray ablation process of Aluminum and Titanium is studied numerically with a 1-D radiation hydrodynamic code RDMG [F. Tinggui et al., Chin. J. Comput. Phys. 16, 199 (1999)], based on which a new scaling relation of the equivalent radiation temperature with the ablative shock velocity in Aluminum plates is proposed, and a novel method is developed for determining simultaneously the radiation temperature and the M-band (2-4 keV) fraction in laser-driven gold Hohlraums.

  14. Spectrochemical analysis of powdered biological samples using transversely excited atmospheric carbon dioxide laser plasma excitation

    NASA Astrophysics Data System (ADS)

    Zivkovic, Sanja; Momcilovic, Milos; Staicu, Angela; Mutic, Jelena; Trtica, Milan; Savovic, Jelena

    2017-02-01

    The aim of this study was to develop a simple laser induced breakdown spectroscopy (LIBS) method for quantitative elemental analysis of powdered biological materials based on laboratory prepared calibration samples. The analysis was done using ungated single pulse LIBS in ambient air at atmospheric pressure. Transversely-Excited Atmospheric pressure (TEA) CO2 laser was used as an energy source for plasma generation on samples. The material used for the analysis was a blue-green alga Spirulina, widely used in food and pharmaceutical industries and also in a few biotechnological applications. To demonstrate the analytical potential of this particular LIBS system the obtained spectra were compared to the spectra obtained using a commercial LIBS system based on pulsed Nd:YAG laser. A single sample of known concentration was used to estimate detection limits for Ba, Ca, Fe, Mg, Mn, Si and Sr and compare detection power of these two LIBS systems. TEA CO2 laser based LIBS was also applied for quantitative analysis of the elements in powder Spirulina samples. Analytical curves for Ba, Fe, Mg, Mn and Sr were constructed using laboratory produced matrix-matched calibration samples. Inductively coupled plasma optical emission spectroscopy (ICP-OES) was used as the reference technique for elemental quantification, and reasonably well agreement between ICP and LIBS data was obtained. Results confirm that, in respect to its sensitivity and precision, TEA CO2 laser based LIBS can be successfully applied for quantitative analysis of macro and micro-elements in algal samples. The fact that nearly all classes of materials can be prepared as powders implies that the proposed method could be easily extended to a quantitative analysis of different kinds of materials, organic, biological or inorganic.

  15. INTERACTION OF LASER RADIATION WITH MATTER: Disturbance of adhesion upon ablation of thin films by laser pulses

    NASA Astrophysics Data System (ADS)

    Fedenev, A. V.; Lipatov, E. I.; Tarasenko, Viktor F.; Orlovskii, Viktor M.; Shulepov, M. A.; Koval', N. N.; Goncharenko, I. M.

    2004-04-01

    The effect of IR and UV laser pulses on thin metal and composite films on glass substrates as a function of the energy density is studied. Upon irradiation by ~300-ns laser pulses with a nonuniform energy-density distribution over the laser-beam cross section, the characteristic regions can be distinguished on the film surface. The dimensions of these regions correlate with the energy distribution in the beam and correspond to the evaporation, melting, and damage conditions caused by thermal stresses. For a uniform energy-density distribution over the laser-beam cross section and a pulse duration of ~20 ns, the adhesion of metal and composite films to glass was disturbed due to induced thermal stresses without substrate melting. The threshold laser-energy densities required for disturbing the adhesion of titanium, titanium nitride, zirconium, niobium, and stainless-steel films on glass substrates are measured. Numerical estimates of the surface temperature and thermal stresses caused by heating show that the film adhesion to a substrate can be overcome by expending a small fraction of the energy, while most of the energy of thermal stresses goes to the formation of cracks and the kinetic energy of escaping film fragments. It is suggested to use pulsed laser radiation to roughly estimate the adhesion of metal and composite films to glass substrates.

  16. Interaction of CO2 laser radiation with a dense Z-pinch plasma

    NASA Astrophysics Data System (ADS)

    Neufeld, C. R.

    1980-01-01

    Results obtained when a TEA-CO2 laser pulse is radially incident on a dense hydrogen Z-pinch plasma are presented. Perturbations of the plasma column are visible on high-speed streak photographs. Spectral measurements indicate that stimulated Brillouin scattering in the underdense plasma regions is the dominant mechanism for the observed backscattering of laser radiation by the plasma column. The time behavior of the backscattered signal can be very complex, both prompt and delayed backscatter having been observed under ostensibly identical experimental conditions. The backscattered power is typically 1-2 percent of the incident laser power.

  17. Influence of laser radiation on the growth and development of seeds of agricultural plants

    NASA Astrophysics Data System (ADS)

    Grishkanich, Alexander; Zhevlakov, Alexander; Polyakov, Vadim; Kascheev, Sergey; Sidorov, Igor; Ruzankina, Julia; Yakovlev, Alexey; Mak, Andrey

    2016-04-01

    The experimental results presented in this study focused on the study of biological processes caused by exposure to the coating layers of the laser green light seed (λ = 532 nm) range for the larch, violet (λ = 405 nm) and red (λ = 640 nm) for spruce. Spend a series of experiments to study the dependence of crop seed quality (spruce and larch from the pine family) from exposure to laser radiation under different conditions. In all the analyzed groups studied seed germination and growth of seedlings exposed to laser exposure, compared with the control group. The results showed that the higher percentage of germination than seeds of the control group.

  18. Enhancement of terahertz radiation by using circularly polarized two-color laser fields

    NASA Astrophysics Data System (ADS)

    Meng, Chao; Chen, Wenbo; Wang, Xiaowei; Lü, Zhihui; Huang, Yindong; Liu, Jinlei; Zhang, Dongwen; Zhao, Zengxiu; Yuan, Jianmin

    2016-09-01

    Terahertz radiation from tunneling ionization of gaseous atoms and molecules in the two-color laser fields with various polarizations has been investigated. We experimentally demonstrate that the efficiency of terahertz emission in the circularly polarized laser fields with the same helicity is 5 times higher than that with linearly polarized two-color femtosecond pulses in high laser intensity. By solving time-dependent Schrödinger equation, this enhancement is well explained based on the analysis of electron tunneling ionization and subsequent dynamics.

  19. Microprocessing of human hard tooth tissues surface by mid-infrared erbium lasers radiation

    NASA Astrophysics Data System (ADS)

    Belikov, Andrey V.; Shatilova, Ksenia V.; Skrypnik, Alexei V.

    2015-03-01

    A new method of hard tooth tissues laser treatment is described. The method consists in formation of regular microdefects on tissue surface by mid-infrared erbium laser radiation with propagation ratio M2<2 (Er-laser microprocessing). Proposed method was used for preparation of hard tooth tissues surface before filling for improvement of bond strength between tissues surface and restorative materials, microleakage reduction between tissues surface and restorative materials, and for caries prevention as a result of increasing microhardness and acid resistance of tooth enamel.

  20. Radiation-pressure acceleration of ion beams driven by circularly polarized laser pulses.

    PubMed

    Henig, A; Steinke, S; Schnürer, M; Sokollik, T; Hörlein, R; Kiefer, D; Jung, D; Schreiber, J; Hegelich, B M; Yan, X Q; Meyer-ter-Vehn, J; Tajima, T; Nickles, P V; Sandner, W; Habs, D

    2009-12-11

    We present experimental studies on ion acceleration from ultrathin diamondlike carbon foils irradiated by ultrahigh contrast laser pulses of energy 0.7 J focused to peak intensities of 5x10(19) W/cm2. A reduction in electron heating is observed when the laser polarization is changed from linear to circular, leading to a pronounced peak in the fully ionized carbon spectrum at the optimum foil thickness of 5.3 nm. Two-dimensional particle-in-cell simulations reveal that those C6+ ions are for the first time dominantly accelerated in a phase-stable way by the laser radiation pressure.

  1. Laser-driven beam lines for delivering intensity modulated radiation therapy with particle beams

    NASA Astrophysics Data System (ADS)

    Hofmann, K. M.; Schell, S.; Wilkens, J. J.

    2013-07-01

    Laser-accelerated particles can provide a promising opportunity for radiation therapy of cancer. Potential advantages arise from combining a compact, cost-efficient treatment unit with the physical advantages in dose delivery of charged particle beams. We consider different dose delivery schemes and the required devices to design a possible treatment unit. The secondary radiation produced in several beam line elements remains a challenge to be addressed.

  2. Photodynamic action of laser radiation and methylene blue on some opportunistic microorganisms of the oral cavity

    NASA Astrophysics Data System (ADS)

    Ivanov, Krill I.; Titorenko, Vladimir A.; Shoub, Gennady M.; Lepilin, Alexander V.; Ovchinnikov, Ilya S.; Mischenko, Oksana S.; Tuchin, Valery V.

    2000-03-01

    We have studied photodynamic action of He-Ne laser radiation on cultures of Staphylococcus (strain 209 P), Streptococcus anhaemolyticus, and total microflora of dental deposit been sensitized by methylene blue. The concentration of the dye was varied from 0.001% to 0.1%, radiation power density was 100 mW/cm2. Irradiated strain was put into thermostat for 24 hours, then the number of colonies was counted and analyzed.

  3. Generation of THz Radiation by Excitation of InAs with a Free Electron Laser

    SciTech Connect

    Mashiko Tani; Shunsuke Kono; Ping Gu; Kiyomi Sakai; Mamoru Usami; Michelle D. Shinn; Joseph F. Gubeli; George Neil; Jingzhou Xu; Roland Kersting; X.-C. Zhang

    2001-01-01

    Terahertz (THz) radiation is generated by exciting an un-doped InAs wafer with a femtosecond free-electron laser (FEL) at the Thomas Jefferson National Accelerator Facility. A microwatt level of THz radiation is detected from the unbiased InAs emitter when it is excited with the femtosecond FEL pulses operated at a wavelength of 1.06 {mu}-m and 10 W average power.

  4. Laser-driven beam lines for delivering intensity modulated radiation therapy with particle beams

    SciTech Connect

    Hofmann, K. M.; Schell, S.; Wilkens, J. J.

    2013-07-26

    Laser-accelerated particles can provide a promising opportunity for radiation therapy of cancer. Potential advantages arise from combining a compact, cost-efficient treatment unit with the physical advantages in dose delivery of charged particle beams. We consider different dose delivery schemes and the required devices to design a possible treatment unit. The secondary radiation produced in several beam line elements remains a challenge to be addressed.

  5. 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

    watts. The gross and microscopic changes following laser irradiation resembled basically lesions produced by other heat producing agents , but differed in...with the effects of other physical agents on piSment formation (3). Laser irradiation during the active phase of hair growth (7 - 9th day) when...reactions. Such changes have been produced both .in the presence or absence of photosensitizing agents acting as energy traosfer agents . (31

  6. Acoustic-wave generation in the process of CO2-TEA-laser-radiation interaction with metal targets in air

    NASA Astrophysics Data System (ADS)

    Apostol, Ileana; Teodorescu, G.; Serbanescu-Oasa, Anca; Dragulinescu, Dumitru; Chis, Ioan; Stoian, Razvan

    1995-03-01

    Laser radiation interaction with materials is a complex process in which creation of acoustic waves or stress waves is a part of it. As a function of the laser radiation energy and intensity incident on steel target surface ultrasound signals were registered and studied. Thermoelastic, ablation and breakdown mechanisms of generation of acoustic waves were analyzed.

  7. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Efficiency of ablative loading of material upon the fast-electron transfer of absorbed laser energy

    NASA Astrophysics Data System (ADS)

    Gus'kov, Sergei Yu; Kasperczuk, A.; Pisarczyk, T.; Borodziuk, S.; Kalal, M.; Limpouch, J.; Ullschmied, J.; Krousky, E.; Masek, K.; Pfeifer, M.; Rohlena, K.; Skala, J.; Pisarczyk, P.

    2006-05-01

    We present the results of experiments on the short-term irradiation of a solid material by a laser beam. The data testify to a rise in efficiency of the energy transfer from the laser pulse to a shock wave due to the fast-electron energy transfer. The experiments were performed with massive aluminium targets on the PALS iodine laser, whose pulse duration (0.4 ns) was much shorter than the time of shock decay and crater formation in the target (50-200 ns). The irradiation experiments were carried out using the fundamental laser harmonic (1.315 μm) with an energy of 360 J. The greater part of the experiments were performed for the radiation intensity exceeding 1015 W cm-2, which corresponded to the efficient generation of fast electrons under the conditions where the relatively long-wavelength iodine-laser radiation was employed. The irradiation intensity was varied by varying the laser beam radius for a specified pulse energy.

  8. Energy gain of an electron by a laser pulse in the presence of radiation reaction.

    PubMed

    Lehmann, G; Spatschek, K H

    2011-10-01

    A well-known no-energy-gain theorem states that an electron cannot gain energy when being overrun by a plane (transverse) laser pulse of finite length. The theorem is based on symmetries which are broken when radiation reaction (RR) is included. It is shown here that an electron, e.g., being initially at rest, will gain a positive velocity component in the laser propagation direction after being overrun by an intense laser pulse (of finite duration and with intensity of order 5×10(22) W/cm(2) or larger). The velocity increment is due to RR effects. The latter are incorporated in the Landau-Lifshitz form. Both linear as well as circular polarization of the laser pulse are considered. It is demonstrated that the velocity gain is proportional to the pulse length and the square of the peak amplitude of the laser pulse. The results of numerical simulations are supported by analytical estimates.

  9. Intense Nanosecond-Pulsed Cavity-Dumped Laser Radiation at 1.04 THz

    NASA Astrophysics Data System (ADS)

    Wilson, Thomas

    2013-03-01

    We report first results of intense far-infrared (FIR) nanosecond-pulsed laser radiation at 1.04 THz from a previously described[2] cavity-dumped, optically-pumped molecular gas laser. The gain medium, methyl fluoride, is pumped by the 9R20 line of a TEA CO2 laser[3] with a pulse energy of 200 mJ. The THz laser pulses contain of 30 kW peak power in 5 nanosecond pulse widths at a pulse repetition rate of 10 Hz. The line width, measured by a scanning metal-mesh FIR Fabry-Perot interferometer, is 100 MHz. The novel THz laser is being used in experiments to resonantly excite coherent ns-pulsed 1.04 THz longitudinal acoustic phonons in silicon doping-superlattices. The research is supported by NASA EPSCoR NNX11AM04A and AFOSR FA9550-12-1-0100 awards.

  10. Propagation and absorption of high-intensity femtosecond laser radiation in diamond

    SciTech Connect

    Kononenko, V V; Konov, V I; Gololobov, V M; Zavedeev, E V

    2014-12-31

    Femtosecond interferometry has been used to experimentally study the photoexcitation of the electron subsystem of diamond exposed to femtosecond laser pulses of intensity 10{sup 11} to 10{sup 14} W cm{sup -2}. The carrier concentration has been determined as a function of incident intensity for three harmonics of a Ti : sapphire laser (800, 400 and 266 nm). The results demonstrate that, in a wide range of laser fluences (up to those resulting in surface and bulk graphitisation), a well-defined multiphoton absorption prevails. We have estimated nonlinear absorption coefficients for pulsed radiation at λ = 800 nm (four-photon transition) and at 400 and 266 nm (indirect and direct two-photon transitions, respectively). It has also been shown that, at any considerable path length of a femtosecond pulse in diamond (tens of microns or longer), the laser beam experiences a severe nonlinear transformation, determining the amount of energy absorbed by the lattice, which is important for the development of technology for diamond photostructuring by ultrashort pulses. The competition between wave packet self-focusing and the plasma defocusing effect is examined as a major mechanism governing the propagation of intense laser pulses in diamond. (interaction of laser radiation with matter. laser plasma)

  11. Plume Tracker: Interactive mapping of volcanic sulfur dioxide emissions with high-performance radiative transfer modeling

    NASA Astrophysics Data System (ADS)

    Realmuto, Vincent J.; Berk, Alexander

    2016-11-01

    We describe the development of Plume Tracker, an interactive toolkit for the analysis of multispectral thermal infrared observations of volcanic plumes and clouds. Plume Tracker is the successor to MAP_SO2, and together these flexible and comprehensive tools have enabled investigators to map sulfur dioxide (SO2) emissions from a number of volcanoes with TIR data from a variety of airborne and satellite instruments. Our objective for the development of Plume Tracker was to improve the computational performance of the retrieval procedures while retaining the accuracy of the retrievals. We have achieved a 300 × improvement in the benchmark performance of the retrieval procedures through the introduction of innovative data binning and signal reconstruction strategies, and improved the accuracy of the retrievals with a new method for evaluating the misfit between model and observed radiance spectra. We evaluated the accuracy of Plume Tracker retrievals with case studies based on MODIS and AIRS data acquired over Sarychev Peak Volcano, and ASTER data acquired over Kilauea and Turrialba Volcanoes. In the Sarychev Peak study, the AIRS-based estimate of total SO2 mass was 40% lower than the MODIS-based estimate. This result was consistent with a 45% reduction in the AIRS-based estimate of plume area relative to the corresponding MODIS-based estimate. In addition, we found that our AIRS-based estimate agreed with an independent estimate, based on a competing retrieval technique, within a margin of ± 20%. In the Kilauea study, the ASTER-based concentration estimates from 21 May 2012 were within ± 50% of concurrent ground-level concentration measurements. In the Turrialba study, the ASTER-based concentration estimates on 21 January 2012 were in exact agreement with SO2 concentrations measured at plume altitude on 1 February 2012.

  12. APPLICATIONS OF LASERS AND OTHER TOPICS IN LASER PHYSICS AND TECHNOLOGY: Influence of atmospheric fluctuations of the induced temperature on the characteristics of laser radiation

    NASA Astrophysics Data System (ADS)

    Banakh, Viktor A.; Smalikho, I. N.

    1987-10-01

    The expression for the function representing the second-order mutual coherence of a laser beam propagating in a turbulent atmosphere under thermal self-interaction conditions is derived in the aberration-free approximation. An analysis is made of the width of a beam, its wind refraction, and the radius of coherence as a function of the initial coherence of the radiation, of conditions of diffraction on the transmitting aperture, and of fluctuations of the wind velocity. It is shown that on increase in the power the coherence radius of cw laser radiation first increases because of thermal defocusing and then decreases due to the appearance (because of fluctuations of the wind velocity) of induced temperature inhomogeneities in air in the beam localization region. The conditions under which fluctuations of the induced temperature have a significant influence on the coherence of the radiation are determined.

  13. Sensitized action of low-level laser radiation mechanism

    NASA Astrophysics Data System (ADS)

    Chichuk, Tatyana V.; Stranadko, Eugeny P.; Lubchenko, G. N.; Podgornaya, E. V.; Pozdnyakova, E. E.; Klebanov, Gennady I.

    1999-12-01

    The goal of this work is to study the laser-induced photosensitized oxidation of lipids of the artificial (lyposomes) and cell's (erythrocytes, leukocytes) membranes and human blood lipoproteins. As a exogenous photosensitizers we are used hematoporphyrin derivatives (HPD) and sulfonated phthalocyanine aluminum (Pc). Irradiation was performed by helium-neon laser (632.8 nm). It was found out the increasing of the products of lipid oxidation in the suspensions of a lyposomes, human blood apo-(beta) -lipoproteins, erythrocytes and leucocytes. Accumulation of the lipid oxidation products depend on as irradiation dose as HPD or Pc concentrations. Interaction of photosensitizers with the lyposomes, lipoproteins and erythrocytes was investigated.

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

    SciTech Connect

    Tsai, C.

    1981-11-01

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

  15. All-optical radiation reaction in head-on laser electron interaction

    NASA Astrophysics Data System (ADS)

    Vranic, Marija; Grismayer, Thomas; Martins, Joana L.; Fonseca, Ricardo A.; Silva, Luis O.

    2016-10-01

    Radiation reaction (RR) accounts for the slowdown of a charged particle that occurs when a significant fraction of its kinetic energy is emitted as radiation. Here we show that this effect could be measured in an all-optical setup using a laser wakefield accelerated electron beam colliding with an intense laser pulse. We employ full-scale 3D PIC simulations to show that one can enter a radiation reaction dominated regime with a GeV electron beam and a 30 fs laser of I = 1021W/cm2. The electrons can lose up to 40% of their initial energy, which can be used as an experimental signature in the spectra. Our results indicate that modern laser facilities provide an exciting opportunity to explore classical RR and the near-future laser facilities can be employed to study the RR beyond classical description. By using higher laser intensities (1022-1023W/cm2) , quantum effects such as Compton scattering and Breit-Wheeler pair production become relevant. We have included these quantum effects in our PIC code OSIRIS through a Monte Carlo module, and performed a detailed numerical study of the transition from classical to quantum RR dominated regime. We identified the distinct features in the electron distribution function that could serve as signatures of quantum radiation reaction, and showed that large-scale infrastructures (e.g. NIF and ELI and next generation of PW-class lasers (e. g. CoReLS, Bella-i, Texas Petawatt, Apollon 10 PW) could be employed to test the physics in these extreme scenarios.

  16. Carbon dioxide (CO2) laser perforation of exposed cranial bone to stimulate granulation tissue.

    PubMed

    Bailin, P L; Wheeland, R G

    1985-06-01

    The technique of CO2 laser perforation of exposed bone has been discussed. The advantages of this rapid and safe technique, which minimizes patient anxiety, limits tissue destruction, and can be performed without anesthesia in an outpatient setting, suggest that it can be considered as a possible alternative treatment to stimulate the production of granulation tissue over exposed bone to allow healing by secondary intention or skin grafting.

  17. CONTROL OF LASER RADIATION PARAMETERS: Enhancement of the efficiency and control of emission parameters of an unstable-resonator chemical oxygen—iodine laser

    NASA Astrophysics Data System (ADS)

    Boreisho, A. S.; Lobachev, V. V.; Savin, A. V.; Strakhov, S. Yu; Trilis, A. V.

    2007-07-01

    The outlook is considered for the development of a high-power supersonic flowing chemical oxygen—iodine laser operating as an amplifier and controlled by radiation from a master oscillator by using an unstable resonator with a hole-coupled mirror. The influence of the seed radiation intensity, the coupling-hole diameter, the active-medium length, and the magnification factor on the parameters of laser radiation is analysed. It is shown that the use of such resonators is most advisable in medium-power oxygen—iodine lasers for which classical unstable resonators are inefficient because of their low magnification factors. The use of unstable resonators with a hole-coupled mirror and injection provides the control of radiation parameters and a considerable increase in the output power and brightness of laser radiation.

  18. Mechanisms of Retinal Damage from Chronic Laser Radiation.

    DTIC Science & Technology

    1975-10-31

    that dose - response curve . Threshold has been fairly well determined for the 457.9 nm line and this is obviously a much lower threshold than the 514.5...significant. The next figure, marked Figure 3, gives the cumulative Gaussian dose - response curve using the laser lines of 514.5 and 488 nm and broadband

  19. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Characteristics of the evolution of a plasma formed by cw and pulse-periodic CO2 laser radiation in various gases

    NASA Astrophysics Data System (ADS)

    Kanevskiĭ, M. F.; Stepanova, M. A.

    1990-06-01

    An investigation was made of the interaction between high-power cw and pulse-periodic CO2 laser radiation and a low-threshold optical breakdown plasma near a metal surface. Characteristics of the breakdown plasma were studied as a function of the experimental conditions. A qualitative analysis was made of the results using a simple one-dimensional model for laser combustion waves.

  20. Communication: A vibrational study of titanium dioxide cation using the vacuum ultraviolet laser pulsed field ionization-photoelectron method.

    PubMed

    Chang, Yih-Chung; Huang, Huang; Luo, Zhihong; Ng, C Y

    2013-01-28

    We have successfully measured the vacuum ultraviolet (VUV) laser photoionization efficiency and pulsed field ionization-photoelectron (PFI-PE) spectra of cold titanium dioxide (TiO(2)) prepared by a supersonically cooled laser ablation source. The VUV-PFI-PE spectrum thus obtained exhibits long progressions of the v(2)(+)(a(1)) bending and the combination of v(1)(+)(a(1)) stretching and v(2)(+)(a(1)) bending vibrational modes of the TiO(2)(+)(X(2)B(2)) ion. The pattern of Franck-Condon factors observed indicates that the O-Ti-O bond angle of the TiO(2)(+)(X(2)B(2)) ion is significantly different from that of the TiO(2)(X(1)A(1)) neutral, whereas the change of the Ti-O bond distance is very minor upon the photoionization transition. The analysis of the PFI-PE bands has made possible the determination of the adiabatic ionization energy for TiO(2), IE(TiO(2)) = 77215.9 ± 1.2 cm(-1) (9.57355 ± 0.00015 eV), the harmonic vibrational frequencies, ω(1)(+) = 829.1 ± 2.0 cm(-1) and ω(2)(+) = 248.7 ± 0.6 cm(-1), and the anharmonic coefficients, χ(11)(+) = 5.57 ± 0.65 cm(-1), χ(22)(+) = 0.08 ± 0.06 cm(-1), and χ(12)(+) = -4.51 ± 0.30 cm(-1) for the TiO(2)(+)(X(2)B(2)) ground state.