Sample records for cw co2 laser

  1. A new approach to model CW CO2 laser using rate equations

    Indian Academy of Sciences (India)


    Nov 11, 2016 ... Theoretical modelling; diffusion-cooled CW CO2 laser; rate equation model; simultaneous linear equations; matrix solution. PACS Nos 42.55. ... In this paper, we extend the application of this model to a CW CO2 laser. However, we should ... mines the output power. Our results agree with the experimentally ...

  2. Single mode operation of a tea CO2 laser by a CW CO2 laser radiation injection

    International Nuclear Information System (INIS)

    Silakhori, K.; Soltanmoradi, F.; Behjat, A.; Montazerghaem, M.; Sadr, R.


    In this research work, single mode operation based on injection of a CW laser beam into TEA CO 2 laser cavity has been demonstrated. The technique has vast applications in research programs for laser spectroscopy and optical pumping. The observed smooth pulse shapes indicated that the system is operating in a single mode of operation, where no additional PZT mounted elements or other cavity stabilizing devices have been used. In addition, it have been observed that the output energy has not been reduced when the laser was operating in a single mode of operation, compared with the case when the laser is operating in the multi-mode regime

  3. A new approach to model CW CO2 laser using rate equations

    Indian Academy of Sciences (India)

    Two popular methods to analyse the operation of CW CO 2 lasers use the temperature model and the rate equation model. Among the two, the latter model directly calculates the population densities in the various vibrational levels connected with the lasing action, and provides a clearer illustration of the processes involved ...

  4. Study of plasma formation in CW CO2 laser beam-metal surface interaction (United States)

    Azharonok, V. V.; Vasilchenko, Zh V.; Golubev, Vladimir S.; Gresev, A. N.; Zabelin, Alexandre M.; Chubrik, N. I.; Shimanovich, V. D.


    An interaction of the cw CO2 laser beam and a moving metal surface has been studied. The pulsed and thermodynamical parameters of the surface plasma were investigated by optical and spectroscopical methods. The subsonic radiation wave propagation in the erosion plasma torch has been studied.

  5. A new approach to model CW CO2 laser using rate equations

    Indian Academy of Sciences (India)


    Nov 11, 2016 ... (2016) 87: 97 c Indian Academy of Sciences. DOI 10.1007/s12043-016-1303-x. A new approach to model CW CO2 laser using rate equations. UTPAL NUNDY1,∗, SUNIL DAGA2 and MANOJ KUMAR3. 1BH-2-76, Kendriya Vihar, Kharghar, Sector-11, Navi Mumbai 410 210, India. 2Laser and Plasma ...

  6. Development of high power CW CO2 laser and material processing techniques

    International Nuclear Information System (INIS)

    Kim, Cheol Jung; Kim, Jeung Mook; Kim, Kwang Suk


    The output characteristics of a longitudinally excited 800 W CW CO 2 laser in Seoul National Unversity was improved. The unstability due to thermal bending was fixed by changing pyrex discharge tubes with quartz tubes. The discharge characteristics was stabilized by using automatic voltage controller. A gas nozzle and X-Y moving table were built to perform laser cutting of zircaloy and stainless steel plate. The optimum nozzle gas pressure was investigated. The effect of shielding gas in prohibiting oxidization of zircaloy surface was examined. (Author)

  7. Interaction of cw CO2 laser radiation with plasma near-metallic substrate surface (United States)

    Azharonok, V. V.; Astapchik, S. A.; Zabelin, Alexandre M.; Golubev, Vladimir S.; Golubev, V. S.; Grezev, A. N.; Filatov, Igor V.; Chubrik, N. I.; Shimanovich, V. D.


    Optical and spectroscopic methods were used in studying near-surface plasma that is formed under the effect CW CO2 laser of (2- 5)x106W/cm2 power density upon stainless steel in He and Ar shielding gases. The variation of plume spatial structure with time has been studied, the outflow of gas-vapor jets from the interaction area has been characterized. The spectra of plasma plume pulsations have been obtained for the frequency range Δf = 0-1 MHz. The temperature and electron concentration of plasma plume have been found under radiation effect upon the target of stainless steel. Consideration has been given to the most probable mechanisms of CW laser radiation-metal non-stationary interaction.

  8. Caries like lesion initiation in sound enamel following CW CO2 laser irradiation: an in vitro study

    International Nuclear Information System (INIS)

    Nafie, A.; Issam, A.; Ali, M. S. R.


    This Study aimed to asses the caries - preventive potential of various CW CO 2 laser parameters, and to explore the effect of the laser power density, and the exposure time on the varies inhibition activity. Materials and Methods: Extracted human premolar teeth were irradiated with three different power densities (7.95, 15.9 and 31.8) W/Cm 2 for three different exposure times (0.2, 0.4 and 0.8) sec of 10.6 μm CW CO 2 laser. All teeth were subjected to caries like lesion formation by 3.5 pH lactic acid for 21 days. The teeth after that were sectioned into ground cross section and the lesion depths were measured using a graticule polarizing microscope. CW CO 2 laser preventive treatments inhibit caries like lesion progression up to 44%. This effect was improved with: (1) Increased power density for each of the three exposure times. (2) Decreased exposure time for each of the three power densities within the limits of the previously listed laser parameters. Conclusion: (1) short exposure time of CW CO 2 laser results in a significant inhibition of the enamel caries like lesion formation. (2) The inhibitory effect depends upon the power density and the exposure time of the laser beam. (3) The optimal CW CO 2 laser parameters used for caries inhibition purpose is achieved with approximately 30 W/Cm 2 power density and 0.2 sec exposure time. (author)

  9. High-speed high-efficiency 500-W cw CO2 laser hermetization of metal frames of microelectronics devices (United States)

    Levin, Andrey V.


    High-speed, efficient method of laser surface treatment has been developed using (500 W) cw CO2 laser. The principal advantages of CO2 laser surface treatment in comparison with solid state lasers are the basis of the method. It has been affirmed that high efficiency of welding was a consequence of the fundamental properties of metal-IR-radiation (10,6 mkm) interaction. CO2 laser hermetization of metal frames of microelectronic devices is described as an example of the proposed method application.

  10. Surface hardening using cw CO2 laser: laser heat treatment, modelation, and experimental work (United States)

    Muniz, German; Alum, Jorge


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

  11. Keyhole depth instability in case of CW CO2 laser beam welding of ...

    Indian Academy of Sciences (India)

    gives rise to irregular humps. Keywords. Ambient and under water welding; keyhole collapse; weld depth instabilities; humps. 1. Introduction. The high-power CO2 laser sources with Gaussian beam distribution are currently used for welding of thick stainless steels (Binda et al 2004). In the case of LBW, heat and fluid flow.

  12. He-Ne and cw CO2 laser long-path systems for gas detection. (United States)

    Grant, W B


    This paper describes the design and testing of a laboratory prototype dual He-Ne laser system for the detection of methane leaks from underground pipelines and solid-waste landfill sites using differential absorption of radiation backscattered from topographic targets. A laboratory-prototype dual cw carbon dioxide laser system also using topographic backscatter is discussed, and measurement results for methanol are given. With both systems, it was observed that the time-varying differential absorption signal was useful in indicating the presence of a gas coming from a nearby source. Limitations to measurement sensitivity, especially the role of speckle and atmospheric turbulence, are described. The speckle results for hard targets are contrasted with those from atmospheric aerosols. The Appendix gives appropriate laser lines and values of absorption coefficients for the hydrazine fuel gases.

  13. High-damage-threshold antireflection coatings on diamond for CW and pulsed CO2 lasers (United States)

    Komlenok, M. S.; Pivovarov, P. A.; Volodkin, B. O.; Pavelyev, V. S.; Anisimov, V. I.; Butuzov, V. V.; Sorochenko, V. R.; Nefedov, S. M.; Mineev, A. P.; Soifer, V. A.; Konov, V. I.


    A multilayer antireflection coating for diamond optics that allows work in the infrared spectral range of 8 –12 µm with minimal optical losses is developed. The optical transmittance of a chemical vapour deposition diamond plate coated with this film on both sides exceeds 94% over the whole specified wavelength range. The coatings deposited on the diamond plate were damage-tested by coherent-wave and pulsed (τ  =  90 ns) CO2 lasers. Results of the tests demonstrated that the coating can withstand prolonged radiation loads with intensity above 3 MW cm‑2 in a continuous-mode laser exposure. In the case of a nanosecond pulsed action, destruction of the coating begins at intensities greater than 50 MW cm‑2.

  14. Passive Q-switching in CW-CO2 laser with SF6 as an intracavity saturable absorber

    International Nuclear Information System (INIS)

    Al-Hawat, Sh.


    A passive Q-switching was applied to a tunable CW CO 2 laser with output power about 3.5 W using SF 6 as a saturable absorber inside the cavity. The Q-Switching phenomenon was studied ( pulse shape, pulse duration, repetition rate and conditions of its generation ) at the spectral lines of 10P(10), 10P(26), 10P(28) and 10P(30) from the branch of 10P of CO 2 laser. These lines had a weak absorption in relation to other lines of this branch, under SF 6 pressure till 0.5 mbar. To control the behaviour of such phenomenon, the gases He and Xe were added separately to SF 6 . It was observed that the Q-switching phenomenon was depended on the added gas pressure of Xe and He, through the repetitive rate of pulses , duration and energy of generated laser pulse. A computational program was written to calculate the Q-switching pulses parameters under similar conditions as those applied in the case of SF 6 +He mixture. A comparison was made with the experimental data , not so big discrepancies were observed between them. In addition to that, absorption coefficients of SF 6 were determined in two cases: the first one when the absorption cell was located outside the laser cavity, and the second one when the cell was located inside the cavity. On the basis of obtained coefficients the absorption cross sections of SF 6 were found and compared with NIST database.(author)

  15. Characteristics of the evolution of a plasma generated by radiation from CW and repetitively pulsed CO2 lasers in different gases (United States)

    Kanevskii, M. F.; Stepanova, M. A.


    The interaction between high-power CW and repetitively pulsed CO2 laser radiation and a low-threshold optical-breakdown plasma near a metal surface is investigated. The characteristics of the breakdown plasma are examined as functions of the experimental conditions. A qualitative analysis of the results obtained was performed using a simple one-dimensional model for laser combustion waves.

  16. 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 (United States)

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


    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.

  17. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Spectroscopic investigation of thermodynamic parameters of a plasma plume formed by the action of cw CO2 laser radiation on a metal substrate (United States)

    Vasil'chenko, Zh V.; Azharonok, V. V.; Filatova, I. I.; Shimanovich, V. D.; Golubev, V. S.; Zabelin, A. M.


    Emission spectroscopy methods were used in an investigation of thermodynamic parameters of a surface plasma formed by the action of cw CO2 laser radiation of (2-5)×106 W cm-2 intensity on stainless steel in a protective He or Ar atmosphere. The spatiotemporal structure and pulsation characteristics of the plasma plume were used to determine the fields of the plasma electron density and temperature.

  18. Temporal characterization of plasma cw high-power CO2 laser-matter interaction: contribution to the welding process control (United States)

    Engel, Thierry; Kane, M.; Fontaine, Joel


    During high-power laser welding, gas ionization occurs above the sample. The resulting plasma ignition threshold is related to ionization potential of metallic vapors from the sample, and shielding gases used in the process. In this work, we have characterized the temporal behavior of the radiation emitted by the plasma during laser welding in order to relate the observed signals to the process parameters.

  19. New cascade laser transitions in CH2F2 pumped with the 9R32 line of a cw CO2 laser

    International Nuclear Information System (INIS)

    Nieswand, C.


    New cascade laser transitions of 12 CH 2 F 2 at 172.50μm, 208.83μm, 220.44μm, 223.99μm,and 250.61μm are reported. A waveguide FIR laser was pumped with a quasi cw 12 C 16 O 2 laser operating on the 9R32 line. Together with the already known lines at 184.3μm, 196.1μm and 235.9μm, the laser lines can be assigned to rotational transitions in the ν 9 vibrational band of 12 CH 2 F 2 and to refill transitions of the vibrational ground state ν 0 . 1 fig., 2 tabs., 6 refs. (author)

  20. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Dynamics of a plasma formed by a surface optical-discharge in a metal vapour interacting with a cw CO2 laser beam (United States)

    Zaikin, A. E.; Levin, A. V.; Petrov, A. L.


    A surface optical-discharge plasma was formed in a metal vapour under normal conditions by steady-state irradiation with a cw CO2 laser delivering radiation of moderate (2-4.5 MW cm-2) intensity. This plasma strongly screened the irradiated surface. Under the selected experimental conditions the optical discharge was not a continuous (steady-state) process. The plasma cloud was displaced along the beam out of the waist to a region where the laser radiation intensity was almost an order of magnitude less than the threshold for excitation of the optical-discharge plasma in the vapour. A strong screening of the metal surface, which could even completely stop evaporation of the metal, was observed. Self-oscillations of the optical-discharge plasma were observed for the first time in a vapour interacting with cw CO2 radiation: this was attributed to screening of the target surface. Within one period of the self-oscillations there were additional hf plasma pulsations which led to stratification of the plasma cloud. The results obtained were interpreted.

  1. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: The mechanism of the drilling of holes in vertical metallic plates by cw CO2 laser radiation (United States)

    Likhanskii, V. V.; Loboiko, A. I.; Antonova, G. F.; Krasyukov, A. G.; Sayapin, V. P.


    The possibility of making a hole in a vertical plate with the aid of laser radiation at a surface temperature not exceeding the boiling point is analysed neglecting the vapour pressure. The mechanism of the degradation of the liquid layer involving a reduction of its thickness, as a result of the redistribution of the molten mass owing to the operation of the force of gravity and of thermocapillary convection, is examined. The theoretical dependence of the critical size of the molten zone on the plate thickness is obtained and a comparison is made with experimental data.

  2. CO2 laser development

    International Nuclear Information System (INIS)



    The research and development programs on high-energy, short-pulse CO 2 lasers were begun at LASL in 1969. Three large systems are now either operating or are being installed. The Single-Beam System (SBS), a four-stage prototype, was designed in 1971 and has been in operation since 1973 with an output energy of 250 J in a 1-ns pulse with an on-target intensity of 3.5 x 10 14 W/cm 2 . The Dual-Beam System (DBS), now in the final stages of electrical and optical checkout, will provide about ten times more power for two-beam target irradiation experiments. Four such dual-beam modules are being installed in the Laser-Fusion Laboratory to provide an Eight-Beam System (EBS) scheduled for operation at the 5- to 10-TW level in 1977. A fourth system, a 100- to 200-TW CO 2 laser, is being designed for the High-Energy Gas Laser Facility (HEGLF) program

  3. CO2 laser cutting

    CERN Document Server

    Powell, John


    The laser has given manufacturing industry a new tool. When the laser beam is focused it can generate one of the world's most intense energy sources, more intense than flames and arcs, though similar to an electron beam. In fact the intensity is such that it can vaporise most known materials. The laser material processing industry has been growing swiftly as the quality, speed and new manufacturing possibilities become better understood. In the fore of these new technologies is the process of laser cutting. Laser cutting leads because it is a direct process substitu­ tion and the laser can usually do the job with greater flexibility, speed and quality than its competitors. However, to achieve these high speeds with high quality con­ siderable know how and experience is required. This information is usually carefully guarded by the businesses concerned and has to be gained by hard experience and technical understanding. Yet in this book John Powell explains in lucid and almost non­ technical language many o...

  4. Effect of argon on the performance of a fast-axial flow CO2 laser (United States)

    Jelvani, S.; Amiri, Kh; Pazokian, H.; Montazerolghaem, M.; Mollabashi, M.; Naeimi, S. A.; Esmaeilpour, D.


    The performance characteristics of a fast-axial flow (FAF) cw CO2 laser are described. The dependences of the output power, efficiency, and discharge voltage on the discharge current of a FAF cw CO2 laser with optimised composition of the CO2:N2:He=1:4.4:7.6 gas mixture with a small amount of argon are studied experimentally at two pressures of 50 and 60 mbar in open and closed cycle regimes of the laser system.

  5. Nuclear activated cw chemical laser

    International Nuclear Information System (INIS)

    Roberts, T.G.


    A cw chemical laser which uses processed radioactive waste to produce active atoms from a chemically inactive gas before being mixed with another molecule such as hydrogen or deuterium is disclosed. This laser uses no toxic or corrosive fuels and does not require any electrical or other type of auxiliary power supply. The energy released by the radioactive material is used to produce the active atoms such as fluorine. This is accomplished by using the radiation products from processed radioactive waste to dissociate the inert gas in the plenum of the laser. The radioactive material is held in the passageway walls of a device similar to a heat exchanger. The exchanger device may be located in the gas generator section of a chemical laser. The inactive gas is passed through the exchanger device and while passing through it the radiation from the radioactive material dissociates the gas, producing a concentration of free active atoms. This active atom generator then feeds the nozzle bank or mixing section of a laser to produce a lasing action

  6. Studies on CO 2 laser marking (United States)

    Ueda, Masahiro; Saitoh, Yoshikazu; Hachisuka, Hideki; Ishigaki, Hiroyuki; Gokoh, Yukihiro; Mantani, Hiroshi

    The nature of CO 2 laser marking was studied with a view to putting these lasers to practical use in the semiconductor industry. The marking is found to be due to surface spattering rather than burning, which is the main factor in YAG laser marking. The visibility greatly increases by the application of a surface treatment such as marker ink, varnish or poster color. The CO 2 laser may therefore be used in place of the YAG laser, now widely used for marking, with some merits: CO 2 laser marking is cheaper and faster, and in addition there is no danger of injury from irradiating laser light.

  7. 2-Micron Laser Transmitter for Coherent CO2 DIAL Measurement (United States)

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


    Carbon dioxide (CO2) has been recognized as one of the most important greenhouse gases. It is essential for the study of global warming to accurately measure the CO2 concentration in the atmosphere and continuously record its variation. A high repetition rate, highly efficient, Q-switched 2-micron laser system as the transmitter of a coherent differential absorption lidar for CO2 measurement has been developed in NASA Langley Research Center. This laser system is capable of making a vertical profiling of CO2 from ground and column measurement of CO2 from air and space-borne platform. The transmitter is a master-slave laser system. The master laser operates in a single frequency, either on-line or off-line of a selected CO2 absorption line. The slave laser is a Q-switched ring-cavity Ho:YLF laser which is pumped by a Tm:fiber laser. The repetition rate can be adjusted from a few hundred Hz to 10 kHz. The injection seeding success rate is from 99.4% to 99.95%. For 1 kHz operation, the output pulse energy is 5.5mJ with the pulse length of 50 ns. The optical-to-optical efficiency is 39% when the pump power is 14.5W. A Ho:YLF laser operating in the range of 2.05 micrometers can be tuned over several characteristic lines of CO2 absorption. Experimentally, a diode pumped Ho:Tm:YLF laser has been successfully used as the transmitter of coherent differential absorption lidar for the measurement of CO2 with a repetition rate of 5 Hz and pulse energy of 75 mJ. For coherent detection, high repetition rate is required for speckle averaging to obtain highly precise measurements. However, a diode pumped Ho:Tm:YLF laser can not operate in high repetition rate due to the large heat loading and up-conversion. A Tm:fiber laser pumped Ho:YLF laser with low heat loading can operate in high repetition rate. A theoretical model has been established to simulate the performance of Tm:fiber laser pumped Ho:YLF lasers. For continuous wave (CW) operation, high pump intensity with small beam

  8. Studies on CO2 Laser Marking


    UEDA, Masahiro; SAITOH, Yoshikazu; HACHISUKA, Hideki; ISHIGAKI, Hiroyuki; GOKOH, Yukihiro; MANTANI, Hiroshi


    The nature of CO2 laser marking was studied with a view to putting these lasers to practical use in the semiconductor industry. The marking is found to be due to surface spattering rather than burning, which is the main factor in YAG laser marking. The visibility greatly increases by the application of a surface treatment such as marker ink, varnish or poster color. The CO2 laser may therefore be used in place of the YAG laser, now widely used for marking, with some merits: CO2 laser marki...

  9. Regional and Global Atmospheric CO2 Measurements Using 1.57 Micron IM-CW Lidar (United States)

    Lin, Bing; Obland, Michael; Nehrir, Amin; Browell, Edward; Harrison, F. Wallace; Dobler, Jeremy; Campbell, Joel; Kooi, Susan; Meadows, Byron; Fan, Tai-Fang; hide


    Atmospheric CO2 is a critical forcing for the Earth's climate, and knowledge of its distribution and variations influences predictions of the Earth's future climate. Accurate observations of atmospheric CO2 are also crucial to improving our understanding of CO2 sources, sinks and transports. To meet these science needs, NASA is developing technologies for the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) space mission, which is aimed at global CO2 observations. Meanwhile an airborne investigation of atmospheric CO2 distributions as part of the NASA Suborbital Atmospheric Carbon and Transport â€" America (ACT-America) mission will be conducted with lidar and in situ instrumentation over the central and eastern United States during all four seasons and under a wide range of meteorological conditions. In preparing for the ASCENDS mission, NASA Langley Research Center and Exelis Inc./Harris Corp. have jointly developed and demonstrated the capability of atmospheric CO2 column measurements with an intensity-modulated continuous-wave (IM-CW) lidar. Since 2005, a total of 14 flight campaigns have been conducted. A measurement precision of approx.0.3 ppmv for a 10-s average over desert and vegetated surfaces has been achieved, and the lidar CO2 measurements also agree well with in-situ observations. Significant atmospheric CO2 variations on various spatiotemporal scales have been observed during these campaigns. For example, around 10-ppm CO2 changes were found within free troposphere in a region of about 200A-300 sq km over Iowa during a summer 2014 flight. Results from recent flight campaigns are presented in this paper. The ability to achieve the science objectives of the ASCENDS mission with an IM-CW lidar is also discussed in this paper, along with the plans for the ACT-America aircraft investigation that begins in the winter of 2016.

  10. CO2, Er: YAG and Nd:YAG lasers in endodontic surgery

    Directory of Open Access Journals (Sweden)

    Daniel Humberto Pozza


    Full Text Available OBJECTIVES: CO2, Er:YAG and Nd:YAG lasers have been used in endodontic surgery. This in vitro study evaluated 1% Rhodamine B dye penetration using computer-assisted morphometry (ImageTool Software® of 108 endodontically treated human permanent canines. MATERIAL AND METHODS: Teeth were divided into 9 groups according to the technique used: A: 90-degree apicoectomy with bur, root-end cavity preparation with ultrasound and filled with MTA; B: 90-degree apicoectomy with bur, root-end cavity prepared with ultrasound and filled with MTA, and treatment of apical surface with CO2 laser (1 W, CW/CW; C: 90-degree apicoectomy with bur, and treatment of apical surface with Nd:YAG laser (150 mJ, 10 Hz; D: 90-degree apicoectomy with bur, and treatment of apical surface with CO2 laser,(1 W, CW/CW; E: apicoectomy with Er:YAG laser (400 mJ, 10 Hz, root-end cavity prepared with ultrasound and filled with MTA; F: apicoectomy with Er:YAG laser (400 mJ, 10 Hz and treatment of apical surface with Nd:YAG laser (150 mJ, 10Hz; G: apicoectomy with CO2 laser (5W, CW/SP, root-end cavity prepared with ultrasound and filled with MTA; H: irradiation of apical end with CO2 laser (1 W, CW/CW; I: irradiation of apical end with Nd:YAG laser (150 mJ, 10 Hz. RESULTS: Dye penetration was found in all specimens at different rates, the lowest penetration occurring in groups C (16.20%, B (17.24% and F (17.84%. CONCLUSIONS: Groups B, C and F represent the best technical sequences to perform endodontic surgery.


    Pozza, Daniel Humberto; Fregapani, Patrícia Wehmeyer; Xavier, Cristina Braga; Weber, João Batista Blessmann; de Oliveira, Marília Gerhardt


    Objectives: CO2, Er:YAG and Nd:YAG lasers have been used in endodontic surgery. This in vitro study evaluated 1% Rhodamine B dye penetration using computer-assisted morphometry (ImageTool Software®) of 108 endodontically treated human permanent canines. Material and methods: Teeth were divided into 9 groups according to the technique used: A: 90-degree apicoectomy with bur, root-end cavity preparation with ultrasound and filled with MTA; B: 90-degree apicoectomy with bur, root-end cavity prepared with ultrasound and filled with MTA, and treatment of apical surface with CO2 laser (1 W, CW/CW); C: 90-degree apicoectomy with bur, and treatment of apical surface with Nd:YAG laser (150 mJ, 10 Hz); D: 90-degree apicoectomy with bur, and treatment of apical surface with CO2 laser (1 W, CW/CW); E: apicoectomy with Er:YAG laser (400 mJ, 10 Hz), root-end cavity prepared with ultrasound and filled with MTA; F: apicoectomy with Er:YAG laser (400 mJ, 10 Hz) and treatment of apical surface with Nd:YAG laser (150 mJ, 10Hz); G: apicoectomy with CO2 laser (5W, CW/SP), root-end cavity prepared with ultrasound and filled with MTA; H: irradiation of apical end with CO2 laser (1 W, CW/CW); I: irradiation of apical end with Nd:YAG laser (150 mJ, 10 Hz). Results: Dye penetration was found in all specimens at different rates, the lowest penetration occurring in groups C (16.20%), B (17.24%) and F (17.84%). Conclusions: Groups B, C and F represent the best technical sequences to perform endodontic surgery. PMID:20027433

  12. CO(2), Er: YAG and Nd:YAG lasers in endodontic surgery. (United States)

    Pozza, Daniel Humberto; Fregapani, Patrícia Wehmeyer; Xavier, Cristina Braga; Weber, João Batista Blessmann; Oliveira, Marília Gerhardt de


    CO(2), Er:YAG and Nd:YAG lasers have been used in endodontic surgery. This in vitro study evaluated 1% Rhodamine B dye penetration using computer-assisted morphometry (ImageTool Software) of 108 endodontically treated human permanent canines. Teeth were divided into 9 groups according to the technique used: A: 90-degree apicoectomy with bur, root-end cavity preparation with ultrasound and filled with MTA; B: 90-degree apicoectomy with bur, root-end cavity prepared with ultrasound and filled with MTA, and treatment of apical surface with CO(2) laser (1 W, CW/CW); C: 90-degree apicoectomy with bur, and treatment of apical surface with Nd:YAG laser (150 mJ, 10 Hz); D: 90-degree apicoectomy with bur, and treatment of apical surface with CO(2) laser,(1 W, CW/CW); E: apicoectomy with Er:YAG laser (400 mJ, 10 Hz), root-end cavity prepared with ultrasound and filled with MTA; F: apicoectomy with Er:YAG laser (400 mJ, 10 Hz) and treatment of apical surface with Nd:YAG laser (150 mJ, 10Hz); G: apicoectomy with CO(2) laser (5W, CW/SP), root-end cavity prepared with ultrasound and filled with MTA; H: irradiation of apical end with CO(2) laser (1 W, CW/CW); I: irradiation of apical end with Nd:YAG laser (150 mJ, 10 Hz). Dye penetration was found in all specimens at different rates, the lowest penetration occurring in groups C (16.20%), B (17.24%) and F (17.84%). Groups B, C and F represent the best technical sequences to perform endodontic surgery.

  13. Plasma Arc Augmented CO2 laser welding

    DEFF Research Database (Denmark)

    Bagger, Claus; Andersen, Mikkel; Frederiksen, Niels


    In order to reduce the hardness of laser beam welded 2.13 mm medium strength steel CMn 250, a plasma arc has been used simultaneously with a 2.6 kW CO2 laser source. In a number of systematic laboratory tests, the plasma arc current, plasma gas flow and distance to the laser source were varied...

  14. Water vapor-nitrogen absorption at CO2 laser frequencies (United States)

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


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

  15. The Role of the CO2 Laser and Fractional CO2 Laser in Dermatology. (United States)

    Omi, Tokuya; Numano, Kayoko


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

  16. Flash scanning the CO2 laser: a revival of the CO2 laser in plastic surgery (United States)

    Lach, Elliot


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

  17. CO2 laser in stapes surgery (United States)

    Jovanovic, Sergije; Schoenfeld, Uwe; Berghaus, Andreas; Fischer, R.; Scherer, Hans H.


    Stapedotomy is not only one of the most successful interventions in otology but also one of the most dangerous for the inner ear. To reduce the risk of damaging middle and inner ear structures through manipulations with conventional instruments, the CO2 laser beam is used for perforating the footplate and removing the suprastructures. This non-contact technique aims at precise and controlled management of middle ear structures. Consideration is given to the impact of experimental data on the clinical application of the CO2 laser in stapes surgery. The discussion covers the advantages and disadvantages with regard to optical and tissue-related properties and points out possible dangers to the inner ear. Our experimental and clinical experience is taken as a basis for examining the surgical technique and the varying demands made on the laser beam in treating the stapedial tendon, crura and footplate. Attention is called to the need for additional instruments. Effective energy parameters for CO2 laser stapedeotomy are evaluated for different lasers. Application of the CO2 laser contributes towards optimization of this high-precision intervention and promises to reduce the incidence of inner ear damages in large numbers of cases. This technique appears useful particularly in difficult anatomic situations and, above all, for revisional operations.

  18. Stereotactic CO2 laser therapy for hydrocephalus (United States)

    Kozodoy-Pins, Rebecca L.; Harrington, James A.; Zazanis, George A.; Nosko, Michael G.; Lehman, Richard M.


    A new fiber-optic delivery system for CO2 radiation has been used to successfully treat non-communicating hydrocephalus. This system consists of a hollow sapphire waveguide employed in the lumen of a stereotactically-guided neuroendoscope. CO2 gas flows through the bore of the hollow waveguide, creating a path for the laser beam through the cerebrospinal fluid (CSF). This delivery system has the advantages of both visualization and guided CO2 laser radiation without the same 4.3 mm diameter scope. Several patients with hydrocephalus were treated with this new system. The laser was used to create a passage in the floor of the ventricle to allow the flow of CSF from the ventricles to the sub-arachnoid space. Initial postoperative results demonstrated a relief of the clinical symptoms. Long-term results will indicate if this type of therapy will be superior to the use of implanted silicone shunts. Since CO2 laser radiation at 10.6 micrometers is strongly absorbed by the water in tissue and CSF, damage to tissue surrounding the lesion with each laser pulse is limited. The accuracy and safety of this technique may prove it to be an advantageous therapy for obstructive hydrocephalus.

  19. CO2 laser used in cosmetology (United States)

    Su, Chenglie


    Cases of various kinds of warts, nevi, papillomas, skin angiomas, ephilises, skin vegetation, scars and brandy noses were vaporized and solidified with a 2.5 - 8 W low power CO2 laser with an overall satisfaction rate up to 99.8% and the satisfaction rate for one time 92%.

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

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


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

  1. The use of laser CO2 in salivary gland diseases (United States)

    Ciolfi, C.; Rocchetti, F.; Fioravanti, M.; Tenore, G.; Palaia, G.; Romeo, U.


    Salivary gland diseases can include reactive lesions, obstructive lesions, and benign tumors. All these clinical entities are slow growing. Salivary glands reactive lesions, such as mucoceles, can result from extravasation of saliva into the surrounding soft tissue or from retention of saliva within the duct. Sialolithiasis, one of the most common obstructive lesions, is generally due to calculi, which are attributed to retention of saliva. Monomorphic adenoma is a salivary gland benign tumor, which is exclusively resulted from proliferation of epithelial cells, with no alterations interesting the connective tissue. The elective therapy of these lesions is surgical excision because sometimes they can be accompained by difficulties during chewing and phonation and can interfere with prosthesis's stability. The aim of the study is to evaluate the efficacy of CO2 laser in the treatment of patients with salivary gland diseases. Three different cases - a mucocele, a scialolithiasis and a monomorphic adenoma - were treated with CO2 laser excision (CW and 4W), under local anesthesia. Two different techniques were used: circumferential incision for the adenoma, and mucosa preservation technique for mucocele and sialolithiasis. In each case final haemostasis was obtained by thermocoagulation, but suture was applied to guarantee good healing by sewing up the flaps. The patients were checked after twenty days and the healing was good. The carbon dioxide laser (CO2 laser) was one of the earliest gas laser to be developed, and is still the highest-power continuous wave laser that is currently available. In dentistry the CO2 laser produces a beam of infrared light with the principal wavelength bands centering around 9.4 and 10.6 micrometers. Laser excision can be very useful in oral surgery. In the cases presented CO2 laser offered, differently from traditional surgery, simplified surgical technique, shorter duration of operation, minimal postoperative pain, minimal scarring

  2. Power stabilized CO2 gas transport laser

    International Nuclear Information System (INIS)

    Foster, J.D.; Kirk, R.F.; Moreno, F.E.; Ahmed, S.A.


    The output power of a high power (1 kW or more) CO 2 gas transport laser is stabilized by flowing the gas mixture over copper plated baffles in the gas channel during operation of the laser. Several other metals may be used instead of copper, for example, nickel, manganese, palladium, platinum, silver and gold. The presence of copper in the laser gas circuit stabilizes output power by what is believed to be a compensation of the chemical changes in the gas due to the cracking action of the electrical discharge which has the effect of diminishing the capactiy of the carbon dioxide gas mixture to maintain the rated power output of the laser. (U.S.)

  3. CO2 laser milling of hard tissue (United States)

    Werner, Martin; Ivanenko, Mikhail; Harbecke, Daniela; Klasing, Manfred; Steigerwald, Hendrik; Hering, Peter


    Drilling of bone and tooth tissue belongs to recurrent medical procedures (screw- and pin-bores, bores for implant inserting, trepanation etc.). Small round bores can be in general quickly produced with mechanical drills. Problems arise however by angled drilling, by the necessity to fulfill the drilling without damaging of sensitive soft tissue beneath the bone, or by the attempt to mill precisely noncircular small cavities. We present investigations on laser hard tissue "milling", which can be advantageous for solving these problems. The "milling" is done with a CO2 laser (10.6 μm) with pulse duration of 50 - 100 μs, combined with a PC-controlled galvanic beam scanner and with a fine water-spray, which helps to avoid thermal side-effects. The damaging of underlying soft tissue can be prevented through control of the optical or acoustical ablation signal. The ablation of hard tissue is accompanied with a strong glowing, which is absent during the laser beam action on soft tissue. The acoustic signals from the diverse tissue types exhibit distinct differences in the spectral composition. Also computer image analysis could be a useful tool to control the operation. Laser "milling" of noncircular cavities with 1 - 4 mm width and about 10 mm depth is particularly interesting for dental implantology. In ex-vivo investigations we found conditions for fast laser "milling" of the cavities without thermal damage and with minimal tapering. It included exploration of different filling patterns (concentric rings, crosshatch, parallel lines and their combinations), definition of maximal pulse duration, repetition rate and laser power, optimal position of the spray. The optimized results give evidences for the applicability of the CO2 laser for biologically tolerable "milling" of deep cavities in the hard tissue.

  4. Finding Optimum Focal Point Position with Neural Networks in CO2 Laser Welding

    DEFF Research Database (Denmark)

    Gong, Hui; Olsen, Flemming Ove


    CO2 lasers are increasingly being utilized for quality welding in production. Considering the high equipment cost, the start-up time and set-up time should be minimized. Ideally the parameters should be set up and optimized more or less automatically. In this article neural networks are designed...... to optimize the focal point position, one of the most critical parameters in laser welding. The feasibility to automatically optimize the focal point position is analyzed. Preliminary tests demonstrate that neural networks can be used to optimize the focal point position with good accuracy in CW CO2 laser...

  5. Stainless Steel Cladding Of Structural Steels By CO2 Laser Welding Techniques (United States)

    Ludovico, A.; Daurelio, G.; Arcamone, O.


    Steel cladding processes are usually performed in different ways: hot roll cladding, strip cladding, weld cladding, explosion forming. For the first time, a medium power (2 KW c.w.) CO2 laser was used to clad structural steels (Fe 37C), 3 and 5 mm thick, with austenitic stainless steels (AISI 304 and AISI 316), 0.5 and 1.5 mm thick. The cladding technique we have developed uses the laser penetration welding process.

  6. High gain, multiatmosphere CO2 laser amplifier (United States)

    Stuart, G. C.; Houtman, H.; Meyer, J.


    A novel TE discharge, 15-mm aperture, multiatmosphere, CO2 laser amplifier is described, with measured electrical characteristics and gain measurements on the 9.294-micron, 9R (16) line. The electrical circuit used in this amplifier is a realistic alternative to the Marx bank or conventional LC inversion circuit and, similarly, it would be useful for excitation of other gas lasers as well. This automatically preionized, double-sided, fourfold LC inversion circuit uses only one spark gap, and it is shown to provide small-signal gains of 5.7 percent/cm, at 120 J/l atm and 10 atm. The generalization to an n-stage device, which would be suitable for higher pressures, and larger apertures, is discussed.

  7. Two-frequency operation of a hybrid TEA CO2 laser and its application to two-frequency pulse injection locking

    International Nuclear Information System (INIS)

    Sasaki, Koichi; Ohno, Hirotaka; Fujii, Takaharu; Tsukishima, Takashige.


    Simultaneous two-frequency oscillation of a hybrid TEA CO 2 laser is exhibited when the cw section is operated in a 'below threshold' state. The output of the hybrid laser thus obtained is injected into a main TEA CO 2 laser to obtain a power-modulated, long-pulse output with a well suppressed gain-switched spike. (author)

  8. CO2 laser resurfacing of the face and neck. (United States)

    Goldman, M P


    Laser resurfacing with the short-pulsed, high-energy CO2 laser has been used to treat photodamaged skin and acne scars. Efficacy and safety have been demonstrated with this technique since 1992. Newer treatment methods, including sequential or combination treatment with the Er:YAG laser have led to increased efficacy with a decrease in adverse sequelae. This article details the author's experience with CO2 laser resurfacing and promotes the use of sequential CO2/Er:YAG laser resurfacing.

  9. Tritium removal by CO2 laser heating

    International Nuclear Information System (INIS)

    Skinner, C.H.; Kugel, H.; Mueller, D.


    Efficient techniques for rapid tritium removal will be necessary for ITER to meet its physics and engineering goals. One potential technique is transient surface heating by a scanning CO 2 or Nd:Yag laser that would release tritium without the severe engineering difficulties of bulk heating of the vessel. The authors have modeled the heat propagation into a surface layer and find that a multi-kW/cm 2 flux with an exposure time of order 10 ms is suitable to heat a 50 micron co-deposited layer to 1,000--2,000 degrees. Improved wall conditioning may be a significant side benefit. They identify remaining issues that need to be addressed experimentally

  10. Tritium removal by CO2 laser heating

    International Nuclear Information System (INIS)

    Skinner, C.H.; Kugel, H.; Mueller, D.


    Efficient techniques for rapid tritium removal will be necessary for ITER (International Thermonuclear Experimental Reactor) to meet its physics and engineering goals. One potential technique is transient surface heating by a scanning CO 2 or Nd:YAG laser that would release tritium without the severe engineering difficulties of bulk heating of the vessel. The authors have modeled the heat propagation into a surface layer and find that a multi-kW/cm 2 flux with an exposure time of order 10 msec is suitable to heat a 50 micron co-deposited layer to 1,000--2,000 degrees. Improved wall conditioning may be a significant side benefit. They identify remaining issues that need to be addressed experimentally

  11. Laser myringotomy with the CO2 Otoscan laser (United States)

    Sedlmaier, Benedikt W.; Jivanjee, Antonio; Schoenfeld, Uwe; Jovanovic, Sergije


    Tympanic ventilation is the treatment of choice for otitis media with effusion (OME). CO2 laser myringotomy has already proven its value and is finding increasing clinical application. The ventilation time in the middle ear is essentially determined by the size of the laser perforation. Perforations exceeding 2 mm in diameter enable tympanic ventilation for about three weeks and thus compete with the ventilation tube in the treatment of OME. IN a prospective study, laser myringotomy is performed in 84 children with OME with the new CO2 laser otoscope Otoscan. The closure time was 17 days in average for a preformation diameter of 2 mm. In the further clinical course, the ear-drums healed without atrophic scar formation. In an observation period of six month the recurrency rate of effusion was approximately 10 percent. Laser myringotomy seems to be an useful method in the operative therapy of secretory otitis media.

  12. ARTICLES: Physical laws governing the interaction of pulse-periodic CO2 laser radiation with metals (United States)

    Vedenov, A. A.; Gladush, G. G.; Drobyazko, S. V.; Pavlovich, Yu V.; Senatorov, Yu M.


    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.

  13. Properties of ZnO whiskers under CO2-laser irradiation

    International Nuclear Information System (INIS)

    Shkumbatyuk, P. S.


    Needlelike ZnO single crystals (whiskers) 0.3-0.8 mm long and 1-10 μm in diameter with a resistivity from 3 x 10 2 to 1 Ω cm have been grown under cw CO 2 -laser irradiation. The whiskers exhibit weak electroluminescence caused by injection from contacts with participation of intrinsic defects, which affect the electric field distribution.

  14. Laser Ablation of Biological Tissue Using Pulsed CO2 Laser

    International Nuclear Information System (INIS)

    Hashishin, Yuichi; Sano, Shu; Nakayama, Takeyoshi


    Laser scalpels are currently used as a form of laser treatment. However, their ablation mechanism has not been clarified because laser excision of biological tissue occurs over a short time scale. Biological tissue ablation generates sound (laser-induced sound). This study seeks to clarify the ablation mechanism. The state of the gelatin ablation was determined using a high-speed video camera and the power reduction of a He-Ne laser beam. The aim of this study was to clarify the laser ablation mechanism by observing laser excision using the high-speed video camera and monitoring the power reduction of the He-Ne laser beam. We simulated laser excision of a biological tissue by irradiating gelatin (10 wt%) with radiation from a pulsed CO 2 laser (wavelength: 10.6 μm; pulse width: 80 ns). In addition, a microphone was used to measure the laser-induced sound. The first pulse caused ablation particles to be emitted in all directions; these particles were subsequently damped so that they formed a mushroom cloud. Furthermore, water was initially evaporated by laser irradiation and then tissue was ejected.

  15. Selective control of HOD photodissociation using CW lasers

    Indian Academy of Sciences (India)


    Keywords. Selective bond-breaking; photodynamic control; photodissociation; CW laser; field optimized initial state (FOIST). 1. Introduction. The promise of using ultra short, high intensity lasers as molecular scissors to cleave bonds selectively continues to attract much theoretical and experimental effort.1–6 The deuterated ...

  16. Studies on CO2-laser Hybrid-Welding of Copper

    DEFF Research Database (Denmark)

    Nielsen, Jakob Skov; Olsen, Flemming Ove; Bagger, Claus


    CO2-laser welding of copper is known to be difficult due to the high heat conductivity of the material and the high reflectivity of copper at the wavelength of the CO2-laser light. THis paper presents a study of laser welding of copper, applying laser hybrid welding. Welding was performed...... as a hybrid CO2-laser and GTAW welding process in 2 mm pure copper sheets. The purpose was to identify maximum welding speeds for the three independent welding processes, i.e. GTAW alone, laser alone and combined processes. After welding, representative welds were quality assesed according to inernational...

  17. Multimode quantum model of a cw atom laser

    International Nuclear Information System (INIS)

    Hope, J.J.; Haine, S.A.; Savage, C.M.


    Full text: Laser cooling allows dilute atomic gases to be cooled to within K of absolute zero. Ultracold gases were first achieved twenty years ago and have since found applications in areas such as spectroscopy, time standards, frequency standards, quantum information processing and atom optics. The atomic analogue of the lasing mode in optical lasers is Bose-Einstein Condensation (BEC), in which a cooled sample of atoms condense into the lowest energy quantum state. This new state of matter was recently achieved in dilute Bose gases in 1995. Atoms coupled out of a BEC exhibit long-range spatial coherence, and provide the coldest atomic source currently available. These atomic sources are called 'atom lasers' because the BEC is analogous to the lasing mode of an optical laser. The high spectral flux from optical lasers is caused by a process called gain-narrowing, which requires continuous wave (cw) operation. Coupling a BEC quickly into an untrapped state forms a coherent atomic beam but it has a spread in momentum as large as the trapped BEC. Coupling the atoms out more slowly reduces the output linewidth at the expense of reducing the overall flux. These atom lasers are equivalent to Q-switched optical lasers. A cw atom laser with gain-narrowing would produce an increasingly monoenergetic output as the flux increased, dramatically improving the spectral flux. A cw atom laser is therefore a major goal of the atom optics community, but there are several theoretical and practical obstacles to understanding the complexities of such a system. The main obstacle to the production of a cw atom laser is the technical difficulties involved in continuously pumping the lasing mode. No complete theory exists which describes a cw atom laser. Complete cw atom laser models require a quantum field description due to their non-Markovian dynamics, significant spatial effects and the dependence of the output on the quantum statistics of the lasing mode. The extreme dimensionality

  18. Industrial Applications Of Low-Power CO2 Lasers (United States)

    Wheeler, John P.


    Until recently, applications of carbon dioxide (CO2) lasers in industry have primarily used high-power laser systems for cutting and welding. Today, the most rapid growth rate is occuring in applications of small, sealed laser systems to soldering, wirestripping, marking, sealing, degating and slitting of a wide variety of materials. In the future, small CO2 laser based systems will be in use in shopping centers and department stores, and unit sales will be in the multiple thousands per year.

  19. Fractional CO2 laser resurfacing for atrophic acne scars

    DEFF Research Database (Denmark)

    Hedelund, Lene; Haak, Christina Skovbølling; Togsverd-Bo, Katrine


    The treatment of acne scars with fractional CO(2) lasers is gaining increasing impact, but has so far not been compared side-by-side to untreated control skin.......The treatment of acne scars with fractional CO(2) lasers is gaining increasing impact, but has so far not been compared side-by-side to untreated control skin....

  20. Comparison of CO2 Laser Cutting with Different Laser Sources

    DEFF Research Database (Denmark)

    Ketting, Hans-Ole; Olsen, Flemmming Ove


    This paper contains CO2 laser cutting results in mild and stainless steel with different laser sources. The main factors which affect the cutting speed and quality are the power, the cutting gas and focal point conditions. Keeping the power and cutting gas constant, the focal point conditions have...... is proven at least for oxyfuel cutting of mild steel, whereas fusion cutting of stainless steel is more complicated.Cutting results from 7 different indus-trial laser sources connected to different moving systems, were used to get information about the importance of the Beam Quality Number K and focal spot...... size,for the maximum cutting speed. One of the 7 laser sources with different focal length and thus different minimum spot size, was then used to investigate more in details the importance of the focal spot size cutting stainless steel with high pressure nitrogen. It looks as if there is a strong...

  1. Clinical evaluation of tumor promotion by CO2 laser (United States)

    Braun, Robert E.; Liebow, Charles


    Cancer promotion by CO2 laser surgery is known to occur in animal models. It is not clear whether these observations are relevant to human disease. To test this, a series of 21 patients with oral lesions treated with CO2 laser surgery were followed for 2 weeks to 32 months with a mean of 10.2 months. Following laser surgery, 83% of lesions presenting as leukoplakia recurred, whereas no recurrences were observed amongst other lesions. This supports the hypothesis that growth factors released in response to CO2 laser surgery could promote cancers in patients with initiated lesions.

  2. Longitudinally excited CO2 laser with multiple laser tubes (United States)

    Uno, Kazuyuki; Akitsu, Tetsuya; Jitsuno, Takahisa


    We developed a longitudinally excited CO2 laser system that was constituted of two or three laser tubes and a single driving circuit. The multiple laser tubes simultaneously produced almost the same short laser pulses with a spike pulse width of about 164 ns and a pulse tail length of about 74 μs with a single driving circuit. The double-tube system was constituted of two 30 cm-long laser tubes with inner diameters of 13 mm and 16 mm and a single driving circuit with an input energy of 2.18 J. The output energy of the 13 mm-tube was 23.3 mJ, and that of the 16 mm-tube was 21.9 mJ at a gas pressure of 4.2 kPa (CO2:N2:He = 1:1:2). The triple-tube system was constituted of three 30 cm-long laser tubes with inner diameters of 9 mm, 13 mm, and 16 mm and a single driving circuit with an input energy of 2.18 J. The output energy of the 9 mm tube was 15.9 mJ, that of the 13 mm tube was 24.1 mJ, and that of the 16 mm tube was 19.2 mJ at a gas pressure of 4.2 kPa. With the same driving circuit and the same input energy, the total output energies of the multitube laser systems were higher than the output energy of a single-tube system.

  3. Clinical effects of CO2 laser on equine diseases (United States)

    Lindholm, Arne; Svensson, Ulf; Collinder, Eje


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

  4. Thermal injuries as a result of CO2 laser resurfacing. (United States)

    Grossman, A R; Majidian, A M; Grossman, P H


    CO2 laser resurfacing of the face for fine wrinkles has gained great popularity over a short period of time. The use of the CO2 laser has proven to be effective in reducing or eliminating fine wrinkles. This tool in the surgeon's armamentarium has been added to those of dermabrasion and chemical peel. The theoretical advantage of the use of the CO2 laser for resurfacing has been better accuracy and reportedly more control of the depth of penetration. The use of the CO2 laser has been welcomed by many cosmetic surgeons. Until now, there have been few reported cases of complications with the use of the CO2 laser. To many, this would sound too good to be true; unfortunately, that is the case. The CO2 laser is a high-energy machine that can indeed cause thermal injury. This thermal injury can result in deep burns to the skin and hypertrophic scarring. We feel this is more common than is currently being reported, and we share our experience as a burn and wound care referral service. During an 18-month period, 20 consecutive patients were referred to our practice who had received injuries from the CO2 laser resurfacing laser. We present here in this review a summary of those injuries. The CO2 resurfacing laser is a very effective tool for the treatment of fine wrinkles, but it is not without the potential for serious complications. We urge caution with the use of the laser and prompt recognition and treatment of thermal injury to the skin.

  5. A Comparison of Potential IM-CW Lidar Modulation Techniques for ASCENDS CO2 Column Measurements From Space (United States)

    Campbell, Joel F.; Lin, Bing; Nehrir, Amin R.; Harrison, F. Wallace; Obland, Michael D.; Ismail, Syed


    Global atmospheric carbon dioxide (CO2) measurements through the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) Decadal Survey recommended space mission are critical for improving our understanding of CO2 sources and sinks. IM-CW (Intensity Modulated Continuous Wave) lidar techniques are investigated as a means of facilitating CO2 measurements from space to meet the ASCENDS science requirements. In previous laboratory and flight experiments we have successfully used linear swept frequency modulation to discriminate surface lidar returns from intermediate aerosol and cloud contamination. Furthermore, high accuracy and precision ranging to the surface as well as to the top of intermediate clouds, which is a requirement for the inversion of the CO2 column-mixing ratio from the instrument optical depth measurements, has been demonstrated with the linear swept frequency modulation technique. We are concurrently investigating advanced techniques to help improve the auto-correlation properties of the transmitted waveform implemented through physical hardware to make cloud rejection more robust in special restricted scenarios. Several different carrier based modulation techniques are compared including orthogonal linear swept, orthogonal non-linear swept, and Binary Phase Shift Keying (BPSK). Techniques are investigated that reduce or eliminate sidelobes. These techniques have excellent auto-correlation properties while possessing a finite bandwidth (by way of a new cyclic digital filter), which will reduce bias error in the presence of multiple scatterers. Our analyses show that the studied modulation techniques can increase the accuracy of CO2 column measurements from space. A comparison of various properties such as signal to noise ratio (SNR) and time-bandwidth product are discussed.

  6. A 10 cm aperture, high quality TEA CO2 laser

    NARCIS (Netherlands)

    Ernst, G.J.


    Experiments have been performed on a corona preionization type 10 cm aperture TEA CO2 laser. For a CO2:N2:He=1: 1: 7: mixture an output energy of 34 joule per liter and for a 1 : 1 : 10 mixture 40 joule per liter could be obtained. The overall efficiency is about 18%. The time behaviour of the

  7. CO2 laser photolysis of clustered ions, (1)

    International Nuclear Information System (INIS)

    Ikezoe, Yasumasa; Soga, Takeshi; Suzuki, Kazuya; Ohno, Shin-ichi.


    Vibrational excitation and the following decomposition of cluster ions by CO 2 laser photons are studied. Characteristics of the cluster ion and the CO 2 laser photon are summarized in their relation to the photolysis of cluster ions. An apparatus was installed, which is composed of (1) corona discharge-jet expansion section (formation of cluster ions), (2) CO 2 laser section (photolysis of cluster ions), and (3) mass spectrometer section. Experimental results of ammonia cluster ions were described. Effects of repeller voltage, shape of repellers, and adiabatic cooling are examined on the formation of ammonia cluster ions by corona discharge-jet expansion method. Collisional dissociation of cluster ions was observed at high repeller voltages. Size distribution of the ammonia cluster ion is discussed in connection with the temperature of cluster ions. Intensity of CO 2 laser was related to decomposition yield of cluster ions. (author)

  8. Application of CO2 laser for electronic components soldering (United States)

    Mascorro-Pantoja, J.; Soto-Bernal, J. J.; Nieto-Pérez, M.; Gonzalez-Mota, R.; Rosales-Candelas, I.


    Laser provides a high controllable and localized spot for soldering joint formation and this is a valuable tool in Sn/Pb Soldering process on electronic industry, in recent years, laser beam welding has become an emerging welding technique, the use of laser in welding area is a high efficiency method. A 60 Watts CO2 continuous laser was used on this study, during welding experimental results indicated the laser could significantly improve speed and weld quality. In this work, the welding interactions of CO2 laser with Sn/Pb wire have been investigated in details through varying the energy ratios of laser. And at the same time, the effect of distance from laser spot to material.

  9. Generation conditions of CW Diode Laser Sustained Plasma (United States)

    Nishimoto, Koji; Matsui, Makoto; Ono, Takahiro


    Laser sustained plasma was generated using 1 kW class continuous wave diode laser. The laser beam was focused on the seed plasma generated by arc discharge in 1 MPa xenon lamp. The diode laser has advantages of high energy conversion efficiency of 80%, ease of maintenance, compact size and availability of conventional quartz based optics. Therefore, it has a prospect of further development compared with conventional CO2 laser. In this study, variation of the plasma shape caused by laser power is observed and also temperature distribution in the direction of plasma radius is measured by optical emission spectroscopy.

  10. Development of a cw-laser-based cavity-ringdown sensor aboard a spacecraft for trace air constituents (United States)

    Awtry, A. R.; Miller, J. H.


    The progress in the development of a sensor for the detection of trace air constituents to monitor spacecraft air quality is reported. A continuous-wave (cw), external-cavity tunable diode laser centered at 1.55 micrometers is used to pump an optical cavity absorption cell in cw-cavity ringdown spectroscopy (cw-CRDS). Preliminary results are presented that demonstrate the sensitivity, selectivity and reproducibility of this method. Detection limits of 2.0 ppm for CO, 2.5 ppm for CO2, 1.8 ppm for H2O, 19.4 ppb for NH3, 7.9 ppb for HCN and 4.0 ppb for C2H2 are calculated.

  11. Selective control of HOD photodissociation using CW lasers

    Indian Academy of Sciences (India)

    Selective control of HOD photodissociation (H-O + D ← HOD → H + O-D) has been theoretically investigated using CW lasers with appropriate carrier frequency and |0, 0〉, |0, 1〉 and |0, 2〉 with zero quantum of excitation in the O-H bond and zero, one and two quanta of excitation in the O-D bond as the initial states. Results ...

  12. High-powered CO2 -lasers and noise control (United States)

    Honkasalo, Antero; Kuronen, Juhani

    High-power CO2 -lasers are being more and more widely used for welding, drilling and cutting in machine shops. In the near future, different kinds of surface treatments will also become routine practice with laser units. The industries benefitting most from high power lasers will be: the automotive industry, shipbuilding, the offshore industry, the aerospace industry, the nuclear and the chemical processing industries. Metal processing lasers are interesting from the point of view of noise control because the working tool is a laser beam. It is reasonable to suppose that the use of such laser beams will lead to lower noise levels than those connected with traditional metal processing methods and equipment. In the following presentation, the noise levels and possible noise-control problems attached to the use of high-powered CO2 -lasers are studied.

  13. Modeling CO2 Laser Ablative Impulse with Polymers

    International Nuclear Information System (INIS)

    Sinko, John E.; Phipps, Claude R.; Sasoh, Akihiro


    Laser ablation vaporization models have usually ignored the spatial dependence of the laser beam. Here, we consider effects from modeling using a Gaussian beam for both photochemical and photothermal conditions. The modeling results are compared to experimental and literature data for CO 2 laser ablation of the polymer polyoxymethylene under vacuum, and discussed in terms of the ablated mass areal density and momentum coupling coefficient. Extending the scope of discussion, laser ablative impulse generation research has lacked a cohesive strategy for linking the vaporization and plasma regimes. Existing models, mostly formulated for ultraviolet laser systems or metal targets, appear to be inappropriate or impractical for applications requiring CO 2 laser ablation of polymers. A recently proposed method for linking the vaporization and plasma regimes for analytical modeling is addressed here along with the implications of its use. Key control parameters are considered, along with the major propulsion parameters needed for laser ablation propulsion modeling.

  14. Helios, a 20 TW CO2 laser fusion facility

    International Nuclear Information System (INIS)

    Ladish, J.S.


    Since June 1978 the Los Alamos Scientific Laboratory's Helios CO 2 laser fusion facility has been committed to an experimental target program to investigate the feasibility of laser produced inertial confinement fusion. This system is briefly described, and preliminary experimental results are reported

  15. Clinical application of CO2 laser in periodontal treatment (United States)

    Hayase, Yasuhiro


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

  16. Interaction of CO2 laser radiation with dense plasma


    Abdel-Raoof, Wasfi Sharkawy


    The instabilities which occur in the interaction of CO2 laser radiation with a dense plasma have been studied. A TEA CO2 laser provided pulses of up to 30 joules of energy with a duration of 50 nanoseconds. By focussing the radiation on to a plane target a focal spot of about 180 micrometers diameter was formed with a irradiance of 10 to 10 W cm. The scattered radiation was collected by a laser focussing lens and analysed with a grating spectrometer. Linear relationships have been found betwe...

  17. CO 2 lasers to destroy defiance of nanobacteria

    Directory of Open Access Journals (Sweden)

    Jafar Kolahi


    Full Text Available Introduction: Nanobacteria are mysterious particles that have spurred one of the biggest controversies in modern microbiology. The apatite mineral around the nanobacteria serves as a primary defense shield against various chemicals and extremely harsh condition. It is combined with a very slow metabolism of nanobacteria. These two items would be the likely explanation for the sever resistance of nanobacteria. The Hypothesis: The CO 2 laser is a continuous wave gas laser and emits infrared light at 9,600-10,600 nm in an easily manipulated focused beam that is well absorbed by water and hydroxyapatite. Hence, it seems logical to postulate that CO 2 laser can be used successfully to destroy defensive external hydroxyapatite layer of nanobacteria. Evaluation of the Hypothesis: Main criticism with this hypothesis is differential radiation of nanobacteria. It is well known that CO 2 laser has high water absorption and consequently can cause unwanted damage to human host tissues.

  18. A comparison of CO2 laser versus traditional stapedectomy outcomes.

    LENUS (Irish Health Repository)

    Ryan, S


    The aim of this study was to audit the introduction of the use of the CO2 laser into our department and to compare hearing outcomes and complication rates in patients who underwent either laser or mechanical stapedectomy. We found that the use of laser is at least as safe as the traditional approach with regards the rate of post-operative complications. One patient in the laser group suffered prolonged post-operative tinnitus, whilst one patient in the traditional group suffered prolonged post-operative vertigo. There was no evidence, however, of improved Air-Bone Gap closure compared to the traditional approach (Pre- and Post-Op Air Bone Gaps of 34 +\\/- 3 and 9 +\\/- 2 for laser stapedectomy versus 35 +\\/- 4 and 13 +\\/- 2 for traditional stapedectomy (mean +\\/- SEM)). In summary, therefore, CO2 laser surgery for otosclerosis is a safe surgical procedure resulting in similar hearing outcomes to that obtained following mechanical stapes surgery.

  19. Maximizing benefits and minimizing risk with CO2 laser resurfacing. (United States)

    Fitzpatrick, Richard E


    Laser resurfacing using the high-energy, pulsed and scanned CO2 laser produces the most dramatic improvement in severe photo-induced facial rhytides and deeply atrophic scars. More recently, the use of short- and long-pulsed erbium lasers in conjunction with CO2 laser resurfacing has been shown to speed healing by removing the upper layer of thermally induced necrotic tissue. The Er:YAG lasers are more superficial ablative tools that inflict less residual thermal damage on the tissue, thus allowing healing to occur without the requisite internal clearance of excessive debris. With continued research and advances in laser surgery, cutaneous resurfacing will be further enhanced with improved outcomes and lessened morbidity.

  20. CO2 Laser Cutting of Hot Stamping Boron Steel Sheets


    Pasquale Russo Spena


    This study investigates the quality of CO2 laser cutting of hot stamping boron steel sheets that are employed in the fabrication of automotive body-in-white. For this purpose, experimental laser cutting tests were conducted on 1.2 mm sheets at varying levels of laser power, cutting speed, and oxygen pressure. The resulting quality of cut edges was evaluated in terms of perpendicularity tolerance, surface irregularity, kerf width, heat affected zone, and dross extension. Experimental tests wer...

  1. Single mode operation of a TEA CO2 laser

    International Nuclear Information System (INIS)

    Wada, Kazuhiro; Tunawaki, Yoshiaki; Yamanaka, Masanobu.


    Single mode operation of a TEA CO 2 laser was performed by using an optical system of Fox-Smith type. Laser beam was taken out from the cavity by using a beam splitter, and was reflected by a mirror back to the cavity. By inserting a Fabry-Perot etalon between the splitter and the mirror, beat of laser pulses can be removed completly. (author)

  2. Investigation of scleral buckling by CO2 laser

    International Nuclear Information System (INIS)

    Maswadi, S.


    This thesis investigates the effect of using the infrared wavelength CO 2 laser (10.6μm) as a localised heat source for inducing scleral buckling on eyes. Retinal detachment disease is a major cause of blindness and the scleral buckling is an important technique used in treatment. A radio-frequency excited 10.6λm laser source is used to heat collagen in the sclera above its shrinkage temperature so as to produce a localised indentation and deformation in the human eye (in vitro). Basic measurements of the onset shrinkage temperatures of porcine and human sclera are taken. Optical properties of sclera tissue at 10.6μm are also determined to provide information about the interaction of the CO 2 laser with the sclera. It is found that CO 2 laser radiation is highly absorbed by the scleral water. Optical diffraction technique is investigated to quantify in-plane deformation in the sclera tissue as result of heating by producing grating on porcine and human sclera using the ArF laser (193nm). Photothermal deflection technique is also used to investigate scleral ablation by using the TEA and Ultrapulse CO 2 laser. This technique provides a useful guide to the regime where ablation rather than heat shrinkage of collagen in the sclera will dominate using the Ultrapulse CO 2 laser. A quantitative assessment of buckling using the technique of projection moire interferometry is described which allows a non-contact measurement to be made of the out-of-plane displacement by laser radiation. In-plane surface strain (shrinkage) has also been demonstrated using in-situ optical microscopy of the laser treated eye. The moire method is suitable to obtain information on buckling in real time and to obtain a three-dimensional view of the eye surface as laser treatment proceeds. A theoretical heat flow model is described for predicting the temperature profile produced in the sclera using the Ultrapulse CO 2 laser. For appropriate exposure parameters the CO 2 laser is found to be an

  3. Advanced Sine Wave Modulation of Continuous Wave Laser System for Atmospheric CO2 Differential Absorption Measurements (United States)

    Campbell, Joel F.; Lin, Bing; Nehrir, Amin R.


    NASA Langley Research Center in collaboration with ITT Exelis have been experimenting with Continuous Wave (CW) laser absorption spectrometer (LAS) as a means of performing atmospheric CO2 column measurements from space to support the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission.Because range resolving Intensity Modulated (IM) CW lidar techniques presented here rely on matched filter correlations, autocorrelation properties without side lobes or other artifacts are highly desirable since the autocorrelation function is critical for the measurements of lidar return powers, laser path lengths, and CO2 column amounts. In this paper modulation techniques are investigated that improve autocorrelation properties. The modulation techniques investigated in this paper include sine waves modulated by maximum length (ML) sequences in various hardware configurations. A CW lidar system using sine waves modulated by ML pseudo random noise codes is described, which uses a time shifting approach to separate channels and make multiple, simultaneous online/offline differential absorption measurements. Unlike the pure ML sequence, this technique is useful in hardware that is band pass filtered as the IM sine wave carrier shifts the main power band. Both amplitude and Phase Shift Keying (PSK) modulated IM carriers are investigated that exibit perfect autocorrelation properties down to one cycle per code bit. In addition, a method is presented to bandwidth limit the ML sequence based on a Gaussian filter implemented in terms of Jacobi theta functions that does not seriously degrade the resolution or introduce side lobes as a means of reducing aliasing and IM carrier bandwidth.

  4. Material Processing with High Power CO2-Lasers (United States)

    Bakowsky, Lothar


    After a period of research and development lasertechnique now is regarded as an important instrument for flexible, economic and fully automatic manufacturing. Especially cutting of flat metal sheets with high power C02-lasers and CNC controlled two or three axes handling systems is a wide spread. application. Three dimensional laser cutting, laser-welding and -heat treatment are just at the be ginning of industrial use in production lines. The main. advantages of laser technology. are - high. accuracy - high, processing velocity - law thermal distortion. - no tool abrasion. The market for laser material processing systems had 1985 a volume of 300 Mio S with growth rates between, 20 % and 30 %. The topic of this lecture are hiTrh. power CO2-lasers. Besides this systems two others are used as machining tools, Nd-YAG- and Eximer lasers. All applications of high. power CO2-lasers to industrial material processing show that high processing velocity and quality are only guaranteed in case of a stable intensity. profile on the workpiece. This is only achieved by laser systems without any power and mode fluctuations and by handling systems of high accuracy. Two applications in the automotive industry are described, below as examples for laser cutting and laser welding of special cylindrical motor parts.

  5. Nonlinear dynamic effects in a two-wave CO2 laser

    International Nuclear Information System (INIS)

    Gorobets, V A; Kozlov, K V; Kuntsevich, B F; Petukhov, V O


    Theoretical and experimental investigations were made of nonlinear dynamic regimes of the operation of a two-wave CO 2 laser with cw excitation in an electric discharge and loss modulation in one of the channels. Nonlinear amplitude - frequency characteristics of each of the laser channels have two low-frequency resonance spikes, associated with forced linear oscillations of two coupled oscillators, and high-frequency spikes, corresponding to doubling of the period of the output radiation oscillations. At low loss-modulation frequencies the intensity oscillations of the output radiation in the coupled channels are in antiphase, whereas at high modulation frequencies the dynamics is cophasal. Nonlinear dynamic effects, such as doubling of the period and of the repetition frequency of the pulses and chaotic oscillations of the output radiation intensity, are observed for certain system parameters. (control of laser radiation parameters)

  6. Assisting Gas Optimization in CO2 Laser Welding

    DEFF Research Database (Denmark)

    Gong, Hui; Olsen, Flemming Ove


    are applied with three different flow rates for each of the gases. A number of systematic laboratory experiments is carried out by employing various experimental designs, 33 and 32 Factorial Design. In the experiments a CO2 laser is used to weld thin sheets of mild steel. The welding specimens are evaluated....... The relations between the gas parameters and signal frequencies are studied. Finally the relationships of the gas parameters and weld characteristics are studied. The possibility of using photo diode signals in controlling the gas parameters is discussed.KeywordsCO2 laser welding, assisting gas parameters...

  7. Effect of Defocused CO2 Laser on Equine Tissue Perfusion

    Directory of Open Access Journals (Sweden)

    Bergh A


    Full Text Available Treatment with defocused CO2 laser can have a therapeutic effect on equine injuries, but the mechanisms involved are unclear. A recent study has shown that laser causes an increase in equine superficial tissue temperature, which may result in an increase in blood perfusion and a stimulating effect on tissue regeneration. However, no studies have described the effects on equine tissue perfusion. The aim of the present study was to investigate the effect of defocused CO2 laser on blood perfusion and to correlate it with temperature in skin and underlying muscle in anaesthetized horses. Differences between clipped and unclipped haircoat were also assessed. Eight horses and two controls received CO2 laser treatment (91 J/cm2 in a randomised order, on a clipped and unclipped area of the hamstring muscles, respectively. The significant increase in clipped skin perfusion and temperature was on average 146.3 ± 33.4 perfusion units (334% and 5.5 ± 1.5°C, respectively. The significant increase in perfusion and temperature in unclipped skin were 80.6 ± 20.4 perfusion units (264% and 4.8 ± 1.4°C. No significant changes were seen in muscle perfusion or temperature. In conclusion, treatment with defocused CO2 laser causes a significant increase in skin perfusion, which is correlated to an increase in skin temperature.

  8. Ethylene tetrafluoroethylene nanofibers prepared by CO2 laser supersonic drawing

    Directory of Open Access Journals (Sweden)

    A. Suzuki


    Full Text Available Ethylene tetrafluoroethylene (ETFE nanofibers were prepared by carbon dioxide (CO2 laser irradiation of asspun ETFE fibers with four different melt flow rates (MFRs in a supersonic jet that was generated by blowing air into a vacuum chamber through the fiber injection orifice. The drawability and superstructure of fibers produced by CO2 laser supersonic drawing depend on the laser power, the chamber pressure, the fiber injection speed, and the MFR. Nanofibers obtained using a laser power of 20 W, a chamber pressure of 20 kPa, and an MFR of 308 g•10 min–1 had an average diameter of 0.303 µm and a degree of crystallinity of 54%.

  9. CO 2 laser photoacoustic spectra and vibrational modes of heroin ...

    Indian Academy of Sciences (India)

    Heroin, morphine and narcotine are very large molecules having 50, 40 and 53 atoms respectively. Moderately high resolution photoacoustic (PA) spectra have been recorded in 9.6 m and 10.6 m regions of CO2 laser. It is very difficult to assign the modes of vibrations for PA bands by comparison with conventional low ...

  10. Fractional CO(2) laser-assisted drug delivery

    DEFF Research Database (Denmark)

    Haedersdal, Merete; Sakamoto, Fernanda H; Farinelli, William A


    Ablative fractional resurfacing (AFR) creates vertical channels that might assist the delivery of topically applied drugs into skin. The purpose of this study was to evaluate drug delivery by CO(2) laser AFR using methyl 5-aminolevulinate (MAL), a porphyrin precursor, as a test drug....

  11. Lithiasis of salivary glands treated with a CO2 laser (United States)

    Grzesiak-Janas, Grazyna; Janas, Anna


    The study compares the results of classical surgical treatment with laserotherapy in lithiasis of submandibular salivary glands. The study included 48 patients, 26 of which were treated with application of a CO2 laser. The follow-up did not reveal any postoperative complications in the course of healing. No relapse of the disease was observed in patients.

  12. Hologaphy of a CO2 laser generated plasma

    International Nuclear Information System (INIS)

    Elkerbout, A.C.H.; Van Dijk, J.W.; Donaldson, T.P.


    An expermental technique for generating holographic interferograms is discussed and illustrated with results obtained on a plasma generated by a 75 J CO 2 laser pulse incident at intensities of approximately 9 x 10 12 W/cm 2 on a plane carbon target. (author)

  13. Absorption Enhanced Liquid Ablation with TEA CO2 Laser

    National Research Council Canada - National Science Library

    Sterling, Enrique


    ... that strongly absorbs radiation in the 8-11 m wavelength interval. A TEA CO2 laser (λ = 10.6 m), 300 ns pulse width and 8 J pulse energy, was used for ablation of water diluted NaBF4 contained in a conical aluminum nozzle...

  14. Efficient TEA CO2 laser based coating removal system

    CSIR Research Space (South Africa)

    Prinsloo, FJ


    Full Text Available A high power 1kW pulsed transversely excited atmospheric CO2 laser that has been developed for the paint stripping of missiles was used to test paint stripping on several metallic and composite aircraft panels to determine the rate at which...

  15. Using a CO2 laser for PIR-detector spoofing

    NARCIS (Netherlands)

    Schleijpen, R.; Putten, F.J.M. van


    This paper presents experimental work on the use of a CO2 laser for triggering of PIR sensors. Pyro-electric InfraRed sensors are often used as motion detectors for detection of moving persons or objects that are warmer than their environment. Apart from uses in the civilian domain, also

  16. Dental hard tissue drilling by longitudinally excited CO2 laser (United States)

    Uno, Kazuyuki; Yamamoto, Takuya; Akitsu, Tetsuya; Jitsuno, Takahisa


    We developed a longitudinally excited CO2 laser with a long optical cavity and investigated the drilling characteristics of dental hard tissue. The CO2 laser was very simple and consisted of a 45-cm-long alumina ceramic pipe with an inner diameter of 13 mm, a pulse power supply, a step-up transformer, a storage capacitance, a spark gap, and a long optical cavity with a cavity length of 175 cm. The CO2 laser produced a short pulse that had a spike pulse with the width of 337 ns and the energy of 1.9 mJ, a pulse tail with the length of 180 μs and the energy of 37.6 mJ, and a doughnut-like beam. In the investigation, a sample was a natural drying human tooth (enamel and dentine). In a processing system, a ZnSe focusing lens with the focal length of 50 mm was used and the location of the focal plane was that of the sample surface. In 1 pulse irradiation, the drilling characteristics depended on the fluence was investigated. In the enamel and dentin drilling, the drilling depth increased with the fluence. The 1 pulse irradiation with the fluence of 21.5 J/cm2 produced the depth of 79.3 μm in the enamel drilling, and the depth of 152.7 μm in the dentin drilling. The short-pulse CO2 laser produced a deeper drilling depth at a lower fluence than long-pulse CO2 lasers in dental hard tissue processing.

  17. Calibrating Laser Gas Measurements by Use of Natural CO2 (United States)

    Webster, Chris


    An improved method of calibration has been devised for instruments that utilize tunable lasers to measure the absorption spectra of atmospheric gases in order to determine the relative abundances of the gases. In this method, CO2 in the atmosphere is used as a natural calibration standard. Unlike in one prior calibration method, it is not necessary to perform calibration measurements in advance of use of the instrument and to risk deterioration of accuracy with time during use. Unlike in another prior calibration method, it is not necessary to include a calibration gas standard (and the attendant additional hardware) in the instrument and to interrupt the acquisition of atmospheric data to perform calibration measurements. In the operation of an instrument of this type, the beam from a tunable diode laser or a tunable quantum-cascade laser is directed along a path through the atmosphere, the laser is made to scan in wavelength over an infrared spectral region that contains one or two absorption spectral lines of a gas of interest, and the transmission (and, thereby, the absorption) of the beam is measured. The concentration of the gas of interest can then be calculated from the observed depth of the absorption line(s), given the temperature, pressure, and path length. CO2 is nearly ideal as a natural calibration gas for the following reasons: CO2 has numerous rotation/vibration infrared spectral lines, many of which are near absorption lines of other gases. The concentration of CO2 relative to the concentrations of the major constituents of the atmosphere is well known and varies slowly and by a small enough amount to be considered constant for calibration in the present context. Hence, absorption-spectral measurements of the concentrations of gases of interest can be normalized to the concentrations of CO2. Because at least one CO2 calibration line is present in every spectral scan of the laser during absorption measurements, the atmospheric CO2 serves

  18. Vibrational Spectrum of HMX at CO2 Laser Wavelengths: A Combined DRIFT and LPAS Study

    Directory of Open Access Journals (Sweden)

    A. Puiu


    Full Text Available The vibrational spectrum of solid standard HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine was investigated. Two spectroscopic techniques were adopted for their different sensitivity and resolution. A preliminary survey of the absorption bands of the compound was performed in the 8000–400 cm−1 spectral range by employing the diffuse reflectance infrared Fourier transform (DRIFT technique at room temperature. The high-resolution line spectrum of HMX was obtained in the 9.2–10.8 μm spectral range by laser photoacoustic spectroscopy (LPAS method, using a line tuneable 10 W stabilised cw CO2 laser light source. By comparing the data collected with the two techniques in the common frequency range, a very good agreement was observed.

  19. The Thomson scattering experiment pulsed by CO2 laser in FT

    International Nuclear Information System (INIS)

    Bartolini, L.; Fornetti, G.; Nardi, M.; Occhionero, G.; Ferri de Collibus, M.


    An experiment carried out to measure the plasma ion temperature Tsub(i) in the tokamak FT in Frascati by Collective Thomson Scattering. A tandem laser system generates two single mode beams (10.6μ) one of which is pulsed and amplified up to levels of 5 MW, 1μs and actively frequency locked to a second continuous wave low pressure CO 2 laser. The pulse beam crosses the plasma and the forward scattered light is collected at angles between 1 degrees centigrade and 1.6 degrees centigrade. An heterodyne technique in which the c.w. beam is the local oscillator is used to measure the Doppler enlarged spectral density of the signal. The experimental apparatus is described and the results are reported and discussed

  20. Differential absorption lidar CO2 laser system for remote sensing of TATP related gases. (United States)

    Pal, Avishekh; Clark, C Douglas; Sigman, Michael; Killinger, Dennis K


    A CW tunable 10.6 microm CO(2) laser differential absorption lidar (DIAL) system has been developed, for the first time to our knowledge, for the remote sensing of triacetone triperoxide (TATP) gas vapors, which have strong absorption lines at several wavelengths, including 3.3, 8.3, and 10.6 microm. The DIAL laser beam was transmitted through an enclosed absorption cell containing TATP or SF(6), and backscattered returns were measured from a retroreflector array target at ranges of 5-100 m. DIAL sensitivity for the detection of TATP was about 0.5 ng/microl [52 parts in 10(6)(ppm)] for a 0.3 m path.

  1. TEA CO2 laser machining of CFRP composite (United States)

    Salama, A.; Li, L.; Mativenga, P.; Whitehead, D.


    Carbon fibre-reinforced polymer (CFRP) composites have found wide applications in the aerospace, marine, sports and automotive industries owing to their lightweight and acceptable mechanical properties compared to the commonly used metallic materials. Machining of CFRP composites using lasers can be challenging due to inhomogeneity in the material properties and structures, which can lead to thermal damages during laser processing. In the previous studies, Nd:YAG, diode-pumped solid-state, CO2 (continuous wave), disc and fibre lasers were used in cutting CFRP composites and the control of damages such as the size of heat-affected zones (HAZs) remains a challenge. In this paper, a short-pulsed (8 μs) transversely excited atmospheric pressure CO2 laser was used, for the first time, to machine CFRP composites. The laser has high peak powers (up to 250 kW) and excellent absorption by both the carbon fibre and the epoxy binder. Design of experiment and statistical modelling, based on response surface methodology, was used to understand the interactions between the process parameters such as laser fluence, repetition rate and cutting speed and their effects on the cut quality characteristics including size of HAZ, machining depth and material removal rate (MRR). Based on this study, process parameter optimization was carried out to minimize the HAZ and maximize the MRR. A discussion is given on the potential applications and comparisons to other lasers in machining CFRP.

  2. Microhardness evaluations of CAD/CAM ceramics irradiated with CO2 or Nd:YAP laser. (United States)

    El Gamal, Ahmed; Rocca, Jean Paul; Fornaini, Carlo; Medioni, Etienne; Brulat-Bouchard, Nathalie


    The aim of this study was to measure the microhardness values of irradiated computer-aided design/computer-aided manufacturing (CAD/CAM) ceramics surfaces before and after thermal treatment. Sixty CAD/CAM ceramic discs were prepared and grouped by material, i.e. lithium disilicate ceramic (Emax CAD) and zirconia ceramic (Emax ZirCAD). Laser irradiation at the material surface was performed with a carbon dioxide laser at 5 Watt (W) or 10 W power in continuous mode (CW mode), or with a neodymium:yttrium aluminum perovskite (Nd:YAP) laser at 10 W on graphite and non-graphite surfaces. Vickers hardness was tested at 0.3 kg f for lithium disilicate and 1 kg f for zirconia. Emax CAD irradiated with CO 2 at 5 W increased microhardness by 6.32 GPa whereas Emax ZirCAD irradiated with Nd:YAP decreased microhardness by 17.46 GPa. CO 2 laser effectively increases the microhardness of lithium disilicate ceramics (Emax CAD).

  3. Long life operation of CO2 mini-TEA lasers (United States)

    Rudko, R. I.; Barnie, J. W.


    Factors affecting the operating and shelf lives of CO2 TEA lasers are analyzed. A method used to counteract the arcing which usually occurs in sealed-off lasers, caused by the generation of oxygen, is described. Test data indicate that the operating life was increased to one million pulses, but the laser output decreased due to a decrease in carbon dioxide. A recombination technique is described during which oxygen was recombined with CO to produce CO2, and by maintaining CO2 percentage at the level of the initial fill, it was found that energy output was constant after an initial insignificant fall off during a 10 millon pulse-life. Shelf-life parameters indicate that the helium permeability and impurity outgassing are determining factors, and for a shelf-life expectancy of 10 years the helium loss rate for a small laser must be less than one millionth atm cc/sec. In addition, the helium diffusion rate must be taken into account and high-alumina ceramic materials are suggested for the manufacture of tube envelopes to increase shelf-life.

  4. CO2 Laser Beat-Wave Experiment in an Unmagnetized Plasma (United States)

    Liu, Fei; Hwang, David; Horton, Robert; Hong, Sean; Evans, Russell


    The ability to remotely generate plasma current in dense plasmas is a basic yet important investigation in experimental plasma physics and fusion energy research. It is even more advantageous if the wave penetration is independent of the electron acceleration process. Plasma current can be generated through beat-wave mixing process by launching two intense electromagnetic waves (φ>>φpe) into plasma. The beat wave formation process can be efficient if the difference frequency of the two pump waves is matched to a local resonant frequency of the medium, i.e. in this case the local plasma frequency. Beat wave can accelerate plasma electrons via quasi-linear Landau process, which has been demonstrated in a low-density plasma using microwaves.footnotetextRogers, J. H. and Hwang, D. Q., Phys. Rev. Lett. v68 p3877 (1992). The CO2 lasers provide the high tunability for the wave-particle interaction experiment at a variety of plasma densities with plasma frequency in THz range. Two sections of Lumonics TEA CO2 lasers have been modified to serve as the two pump wave sources with peak power over 100MW. The development of the tunable CO2 lasers, a high-density plasma target source and diagnostics system will be presented. The initial results of unbalanced beat-wave experiment using one high-power pulsed and one low-power CW CO2 lasers will be presented and discussed using the independent plasma source to control the φpe of the interaction region. This work is supported by U.S. DOE under Contract No. DE-FG02-10ER55083.

  5. Tunable single-longitudinal-mode operation of an injection-locked TEA CO2 laser. [ozone absorption spectroscopy (United States)

    Megie, G.; Menzies, R. T.


    The tunable single-longitudinal-mode operation of a TEA CO2 laser by an injection technique using a CW waveguide laser as the master oscillator is reported. With the experimental arrangement described, in which the waveguide laser frequency is tuned to correspond to one of the oscillating longitudinal modes of the TEA laser, single-longitudinal-mode operation was achieved with no apparent reduction in the TEA output energy, on various CO2 lines with frequency offsets from the line center as large as 300 MHz. The capability of this technique for high-resolution spectroscopy or atmospheric lidar studies is demonstrated by the recording of the absorption spectrum of a strong ozone line.

  6. Frequenzabstimmbarer CO2-Flachkanal-Laser mit strahlformenden Siliziumgittern


    Schulz, Roland Günter


    Im Rahmen dieser Arbeit wurde ein linienselektives CO2-Lasersystem aufgebaut, an dem verschiedene Resonatorkonfigurationen getestet werden konnten. Der Laser wurde dabei in einer Flachkanalbauweise realisiert. In dem Volumen zwischen den Elektroden wird das Lasergas mittels einer HF-Gasentladung angeregt. Dieses Konzept hat den Vorteil, dass die Laserleistung nicht mehr nur proportional zur Länge der Entladungsstruktur, wie bei einem klassischen rohrförmigen Gasentladungslaser, ist, sondern p...

  7. Treatment of acne scarring with fractional CO2 laser. (United States)

    Qian, Hui; Lu, Zhong; Ding, Huilin; Yan, Shuxian; Xiang, Leihong; Gold, Michael H


    Fractional ablative CO(2) laser therapy is based on the theory of fractional photothermolysis. It can be effective in treating acne scars in a less invasive fashion than conventional ablative CO(2) laser therapy. In this clinical study, the safety and efficacy of a novel CO(2) fractional ablative laser was investigated for the treatment of facial atrophic acne scarring in Chinese individuals. A total of 31 patients (11 females, 20 males, Fitzpatrick skin phototypes III-IV) with facial acne scarring received three sequential fractional treatments over a 6-month period. Outcome measurements included blinded evaluations of before and after photographs by two physicians at 3 and 12 months after the final treatment. Global improvement was noted as well as any untoward events. At the 12 months follow-up time period, 12.9% of the patients showed excellent improvement in their acne scars, while 38.71% noted good to fair results. The clinical response at the 12-month follow-up visit tended to be better than at the 3-month follow-up visit, but was not statistically significant. Four patients experienced post-treatment and transient PIH but three patients were noted to have prolonged erythema. There was no evidence hypopigmentation or worsening of the scarring in any of the study patients. This high-energy pulsed and cool-scanned fractional ablative CO(2) laser system is safe and effective for facial atrophic acne scarring. Improvement in scarring was noted in the majority of patients with minimal discomfort and minimal downtime. Continued improvement over time is also an important clinical finding.

  8. Problems in the development of autonomous mobile laser systems based on a cw chemical DF laser

    International Nuclear Information System (INIS)

    Aleksandrov, B P; Bashkin, A S; Beznozdrev, V N; Parfen'ev, M V; Pirogov, N A; Semenov, S N


    The problems involved in designing autonomous mobile laser systems based on high-power cw chemical DF lasers, whose mass and size parameters would make it possible to install them on various vehicles, are discussed. The need for mobility of such lasers necessitates special attention to be paid to the quest for ways and means of reducing the mass and size of the main laser systems. The optimisation of the parameters of such lasers is studied for various methods of scaling their systems. A complex approach to analysis of the optical scheme of the laser system is developed. (special issue devoted to the 80th anniversary of academician n g basov's birth)

  9. Compressive failure in sapphire under CO2 laser heating (United States)

    Miles, P. A.; Gallagher, J.; Gentilman, R. L.


    Irreversible changes were observed in sapphire crystals subjected to surface heating by CO2 laser irradiation at levels above 300 watts/square centimeter. The changes are interpreted as due to plastic flow under compressive stress at temperatures above 900 C. The recognition of possible compressive failures in refractory oxides is of importance in defining laser tolerance levels in high power optics, in the design of laser heating experiments to assess the thermal shock resistance of materials, and possibly in the field of laser assisted machining of ceramics. A detailed thermomechanical analysis was carried out to predict the temperature and stress conditions throughout disk samples as a function of time, heat flux level and flux distribution. Compressive stresses in excess of 200,000 psi were generated. Compressive failure is likely to precede tensile fracture in most experiments where partially heated disks are used.

  10. Parametric study of intersatellite CO2 laser data links (United States)

    Bonek, E.; Lutz, H.

    The performance capability of current CO2 laser communication tecnology for intersatellite data links is evaluated. The link parameters, such as the distance, bit rate, ac signal-to-noise ratio, are related to the masses and the prime power requirements of satellite laser terminals using variables like the telescope (antenna) aperture diameter and the transmitted laser power. It is found that high data rates could be readily transmitted with telescopes of the order of only 10 cm in diameter, with the complte laser data terminals weighing between 25 kg and 70 kg and consuming prime power in the 90-300 W range. In addition, these terminals would require only about 0.1 cu m or less of volume and a very low movable antenna mass, which would alleviate constraints on satellite attitude control units in remote sensing missions.

  11. Simulation Studies of Satellite Laser CO2 Mission Concepts (United States)

    Kawa, S. R.; Mao, J.; Abshire, J. B.; Collatz, G. J.; Sun, X.; Weaver, C. J.; Browell, E. V.


    Results of mission simulation studies are presented for a laser-based atmospheric CO2 sounder. The simulations are based on real-time carbon cycle process modeling and data analysis. The mission concept corresponds to ASCENDS as recommended by the US National Academy of Sciences Decadal Survey. Compared to passive sensors, active (lidar) sensing of CO2 from space has several potentially significant advantages that hold promise to advance CO2 measurement capability in the next decade. Although the precision and accuracy requirements remain at unprecedented levels of stringency, analysis of possible instrument technology indicates that such sensors are more than feasible. As a prerequisite for quantitative sensor evaluation we have assembled a relatively complete description of the atmospheric and surface state that is needed to estimate the random error component of prospective CO2 measurements. The state is obtained from meteorological data assimilation and satellite measurements from MODIS and CALIPSO. The resulting error distributions will be used in inverse studies to estimate the fidelity of surface flux estimation from the laser observations. Radiative transfer model calculations, an instrument model with representative errors, and a simple retrieval approach complete the cycle from "nature" run to "pseudo-data" CO2 with error bounds. The results indicate that within reasonable technological assumptions for the system performance, high measurement precision can be obtained that will fulfill the nominal ASCENDS objectives. Several mission and instrument configuration options are examined, and the sensitivity to key design variables is shown. Examples are also shown of how the resulting pseudo-measurements might be used to address key carbon cycle science questions.

  12. Towards absolute laser spectroscopic CO2 isotope ratio measurements (United States)

    Anyangwe Nwaboh, Javis; Werhahn, Olav; Ebert, Volker


    Knowledge of isotope composition of carbon dioxide (CO2) in the atmosphere is necessary to identify sources and sinks of this key greenhouse gas. In the last years, laser spectroscopic techniques such as cavity ring-down spectroscopy (CRDS) and tunable diode laser absorption spectroscopy (TDLAS) have been shown to perform accurate isotope ratio measurements for CO2 and other gases like water vapour (H2O) [1,2]. Typically, isotope ratios are reported in literature referring to reference materials provided by e.g. the International Atomic Energy Agency (IAEA). However, there could be some benefit if field deployable absolute isotope ratio measurement methods were developed to address issues such as exhausted reference material like the Pee Dee Belemnite (PDB) standard. Absolute isotope ratio measurements would be particularly important for situations where reference materials do not even exist. Here, we present CRDS and TDLAS-based absolute isotope ratios (13C/12C ) in atmospheric CO2. We demonstrate the capabilities of the used methods by measuring CO2 isotope ratios in gas standards. We compare our results to values reported for the isotope certified gas standards. Guide to the expression of uncertainty in measurement (GUM) compliant uncertainty budgets on the CRDS and TDLAS absolute isotope ratio measurements are presented, and traceability is addressed. We outline the current impediments in realizing high accuracy absolute isotope ratio measurements using laser spectroscopic methods, propose solutions and the way forward. Acknowledgement Parts of this work have been carried out within the European Metrology Research Programme (EMRP) ENV52 project-HIGHGAS. The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union. References [1] B. Kühnreich, S. Wagner, J. C. Habig,·O. Möhler, H. Saathoff, V. Ebert, Appl. Phys. B 119:177-187 (2015). [2] E. Kerstel, L. Gianfrani, Appl. Phys. B 92, 439-449 (2008).

  13. CO2 laser-driven Stirling engine. [space power applications (United States)

    Lee, G.; Perry, R. L.; Carney, B.


    A 100-W Beale free-piston Stirling engine was powered remotely by a CO2 laser for long periods of time. The engine ran on both continuous-wave and pulse laser input. The working fluid was helium doped with small quantities of sulfur hexafluoride, SF6. The CO2 radiation was absorbed by the vibrational modes of the sulfur hexafluoride, which in turn transferred the energy to the helium to drive the engine. Electrical energy was obtained from a linear alternator attached to the piston of the engine. Engine pressures, volumes, and temperatures were measured to determine engine performance. It was found that the pulse radiation mode was more efficient than the continuous-wave mode. An analysis of the engine heat consumption indicated that heat losses around the cylinder and the window used to transmit the beam into the engine accounted for nearly half the energy input. The overall efficiency, that is, electrical output to laser input, was approximately 0.75%. However, this experiment was not designed for high efficiency but only to demonstrate the concept of a laser-driven engine. Based on this experiment, the engine could be modified to achieve efficiencies of perhaps 25-30%.

  14. Subsurface plasma in beam of continuous CO2-laser (United States)

    Danytsikov, Y. V.; Dymshakov, V. A.; Lebedev, F. V.; Pismennyy, V. D.; Ryazanov, A. V.


    Experiments performed at the Institute of Atomic Energy established the conditions for formation of subsurface plasma in substances by laser radiation and its characteristics. A quasi-continuous CO2 laser emitting square pulses of 0.1 to 1.0 ms duration and 1 to 10 kW power as well as a continuous CO2 laser served as radiation sources. Radiation was focused on spots 0.1 to 0.5 mm in diameter and maintained at levels ensuring constant power density during the interaction time, while the temperature of the target surface was measured continuously. Metals, graphite and dielectric materials were tested with laser action taking place in air N2 + O2 mixtures, Ar or He atmosphere under pressures of 0.01 to 1.0 atm. Data on radiation intensity thresholds for evaporation and plasma formation were obtained. On the basis of these thresholds, combined with data on energy balance and the temperature profile in plasma layers, a universal state diagram was constructed for subsurface plasma with nonquantified surface temperature and radiation intensity coordinates.

  15. CO2 laser-assisted deep sclerectomy in glaucoma patients. (United States)

    Skaat, Alon; Goldenfeld, Modi; Cotlear, Daniel; Melamed, Shlomo


    To evaluate the safety and efficacy of CO2 laser-assisted deep sclerectomy surgery (CLASS) in patients with open angle glaucoma. A prospective single-arm, nonrandomized clinical investigation for the evaluation of technology. Fifteen eyes of 15 consecutive patients diagnosed with either primary open angle glaucoma or pseudoexfoliation glaucoma who were the candidates for glaucoma filtration surgery were included. Laser-assisted deep sclerectomy using a CO2 laser system was performed in all patients. A half-thickness scleral flap was created, the use of 0.04% mitomycin C for 60 seconds was left at the surgeon's discretion, and a CO2 laser with a beam-manipulating system was used to achieve deep scleral ablation and unroofing of Schlemm's canal zone. Visual acuity, complete ophthalmologic examination, and intraocular pressure (IOP) were measured and documented at baseline, 1, 2, 4, and 6 weeks and at 3, 6, and 12 months, respectively. Complete success was defined as 5≤IOP≤21 mm Hg and 20% IOP reduction with no medication at the 12-month endpoint visit. Qualified success was defined as a similar IOP reduction with medication. The preoperative IOP of 27.3±4.2 mm Hg (mean±SD) dropped to 15.0±3.7 mm Hg at 6 months and 16.6±3.4 mm Hg at 12 months postoperatively, yielding an average IOP reductions at 6 and 12 months of 13.1±4.3 mm Hg (45.1%; 95% CI, 11, 15.3) and 11.5±5.5 mm Hg (39.2%; 95% CI, 8.8, 14.3), respectively (P<0.001). The complete success rate after 12 months was 45.5%, whereas qualified success was 90.9%. Mitomycin C was used in 76.9% of the CLASS subjects.

  16. Lap and butt joints of dissimilar stainless steels welded by CO2 laser (United States)

    Daurelio, Giuseppe; Dionoro, G.; Memola Capece Minutolo, F.; Panagopoulos, Christos N.


    This work concerns the lap welding of dissimilar (AISI 304 - 430, AISI 430 - 304, AISI 316 - 430, and AISI 430 - 316) stainless steels and the butt welding of dissimilar (AISI 304 - 316 and AISI 304 - 430) ones using a fast axial flow 2 kW cw CO2 laser (B.O.C. Laser Ltd.). Two covering gases, He and N2, are used fed coaxially to the laser beam through a 12 mm outlet diameter nozzle at a flow rate varying from 1.67 to 1.87 X 10-3)m3/s. The influence of the process parameters, such as power level, covering gas, and speed on the quality of the welded joints is examined. In the second part of the work laser lap and butt welds of dissimilar stainless steels are characterized by macro and micro graphic investigations to enable structural evaluations. Fillet weld morphology and quality of the same specimens is examined for the two different covering gases, He and N2. Moreover, the different structural aspects of the melted zones obtained with laser welds of the same pair of stainless steels, but with the beam impinging first on the austenitic stainless steel (e.g., AISI 304 - 430) and then the ferritic one (e.g., AISI 430 - 304), or vice versa, are also studied and evaluated.

  17. Progress Toward Measuring CO2 Isotopologue Fluxes in situ with the LLNL Miniature, Laser-based CO2 Sensor (United States)

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


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

  18. A High Power CH3OH Laser System Using Stark Stabilized CO2 Pump Lasers (United States)

    Hutchinson, D. P.; Bennett, C. A.; Lee, J.; Fl etcher, L. K.; Ma, C. H.; Vander Sluis, K. L.


    A dual channel, 119μm wavelength laser system has been constructed for the ATF experiment at Oak Ridge. The pump lasers utilize external Stark cells for locking the CO2 laser to the absorption frequency of the CH3OH lasers. Stark plates have also been attached to the dielectric waveguide resonators of the FIR lasers to affect precise tuning of the 119 μm lasers.

  19. Laser plant "Iguana" for transmyocardial revascularization based on kW-level waveguide CO2 laser (United States)

    Panchenko, Vladislav Y.; Bockeria, L. A.; Berishvili, I. I.; Vasiltsov, Victor V.; Golubev, Vladimir S.; Ul'yanov, Valery A.


    For many years the Institute on Laser and Information Technologies RAN has been developing a concept of high-power industrial CO2 lasers with diffusion cooling of the working medium. The paper gives a description of the laser medical system Iguana for transmyocardial laser revascularization (TMLR) as an example of various applications of high-power waveguide CO2 lasers. The clinical results of the TMLR method application in surgical treatment are presented. The methods of determination of the time, when the laser beam passes through the demarcation line between myocardium tissue and blood, are discussed.

  20. Two-step resonance ionization spectroscopy of Na atomic beam using cw and pulsed lasers

    International Nuclear Information System (INIS)

    Katsuragawa, H.; Minowa, T.; Shimazu, M.


    Two-step photoionization of sodium atomic beam has been carried out using a cw and a pulsed dye lasers. Sodium ions have been detected by a time of flight method in order to reduce background noise. With a proper power of the pulsed dye laser the sodium atomic beam has been irradiated by a resonant cw dye laser. The density of the sodium atomic beam is estimated to be 10 3 cm -3 at the ionization area. (author)

  1. CW-Laser-Induced Solid-State Reactions in Mixed Micron-Sized Particles of Silicon Monoxide and Titanium Monoxide: Nano-Structured Composite with Visible Light Absorption

    Czech Academy of Sciences Publication Activity Database

    Křenek, T.; Tesař, J.; Kupčík, Jaroslav; Netrvalová, M.; Pola, M.; Jandová, Věra; Pokorná, Dana; Cuřínová, Petra; Bezdička, Petr; Pola, Josef


    Roč. 27, č. 6 (2017), s. 1640-1648 ISSN 1574-1443 Institutional support: RVO:61388980 ; RVO:67985858 Keywords : Cw CO2 laser heating * IR laser imaging * Silicon monoxide * Solid state redox reactions * Ti/Si/O composite * Titanium monoxide Subject RIV: CA - Inorganic Chemistry; CI - Industrial Chemistry, Chemical Engineering (UCHP-M) OBOR OECD: Inorganic and nuclear chemistry; Chemical process engineering (UCHP-M) Impact factor: 1.577, year: 2016

  2. Life testing of metal-ceramic CO2 lasers (United States)

    Fahlen, T. S.; Radecki, D. J.; Reynolds, R. S.; Targ, R.


    The main purpose of this program was to determine the life characteristics of nine space-qualified, metal-ceramic CO2 lasers. Lifetimes ranged between about 400 hours to over 2000 hours (the limit of testing) with a high degree of consistency in like groups. In all cases the tubes which had failed could be restored to near their original power by doubling the cathode current for 30 minutes. Periodic rejuvenation allowed operation for the full 2000 hours on all tubes. The failure mechanism appears to involve formation of NiO and C on the nickel cathode emission surface with subsequent absorption of tube gases.

  3. CO2-laser photoacoustic detection of gaseous n-pentylacetate

    Czech Academy of Sciences Publication Activity Database

    Herecová, L.; Hejzlar, T.; Pavlovský, J.; Míček, D.; Zelinger, Zdeněk; Kubát, Pavel; Janečková, B.; Nevrlý, Václav; Bitala, P.; Střižík, Michal; Klouda, E.; Civiš, Svatopluk


    Roč. 256, č. 1 (2009), s. 109-110 ISSN 0022-2852 R&D Projects: GA MŠk OC 111; GA MŠk LC06071; GA ČR GA202/06/0216; GA MŽP SPII1A0/45/07 Institutional research plan: CEZ:AV0Z40400503; CEZ:AV0Z20760514 Keywords : n-pentylacetate * CO2 laser photoacoustic spectroscopy * FTIR spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.542, year: 2009

  4. Diode laser probe of CO2 vibrational excitation produced by collisions with hot deuterium atoms from the 193 nm excimer laser photolysis D2S

    International Nuclear Information System (INIS)

    O'Neill, J.A.; Cai, J.Y.; Flynn, G.W.; Weston, R.E. Jr.


    The 193 nm excimer laser photolysis of D 2 S in D 2 S/CO 2 mixtures produces fast deuterium atoms (E/sub TR/approx.2.2 eV) which vibrationally excite CO 2 molecules via inelastic translation--vibration/rotation (T--V/R) energy exchange processes. A high resolution (10 -3 cm -1 ) cw diode laser probe was used to monitor the excitation of ν 3 (antisymmetric stretch) and ν 2 (bend) vibrations in CO 2 . The present results are compared with previous experiments involving hot hydrogen atom excitation of CO 2 in H 2 S/CO 2 mixtures as well as with theoretical calculations of the excitation probability. The probability for excitation of a ν 3 quantum in CO 2 is about 1%--2% per gas kinetic D/CO 2 collision. Bending (ν 2 ) quanta are produced about eight times more efficiently than antisymmetric stretching (ν 3 ) quanta. The thermalization rate for cooling hot D atoms below the threshold for production of a ν 3 vibrational quantum corresponds to less than 2 D*/D 2 S collisions or 15 D*/CO 2 collisions

  5. Low density, non-ablative fractional CO2 laser rejuvenation. (United States)

    Christiansen, Kaare; Bjerring, Peter


    Fractional skin rejuvenation has gained increased interest since its introduction in 2003. Both non-ablative and ablative lasers as well as different treatment techniques have been devised. Recent clinical studies indicate that a paradigm of low spot density combined with high fluences tend to produce better clinical results and less risk of post-inflammatory hyperpigmentation in darker skin types. The present study is focused on investigations of the clinical outcome by non-ablative fractional CO(2) treatments with a single pass with low spot density. A CO(2) laser was equipped with a scanner enabling it to perform fractional treatments with 36, 64 or 100 microthermal zones (MTZ)/cm(2). Twelve patients participated in the study. The perioral area was treated three times with 1-month intervals using a spot density of 64 MTZ/cm(2), a spot diameter of 0.5 mm, a micro-beam energy of 36-60 mJ, and a pulse duration of 3-5 milliseconds. Follow-up was performed 3 months after the last treatment. At the 3-month follow-up 72.7% of the volunteers had obtained improvement in ultrasonographically determined dermal density, and the average improvement was 40.2% (SD: 48.0%). This improvement was statistically significant (Plaser treatments.

  6. Technology of discharge and laser resonators for high power CO2 lasers. Koshutsuryoku CO2 laser ni tsukawareru hoden reiki laser kyoshinki gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    Takenaka, Y.; Kuzumoto, M. (Mitsubishi Electric Corp., Tokyo (Japan))


    This paper describes discharge excitation technology and resonator technology as basic technologies for high power CO2 lasers. As a result of progress in high-frequency power element techniques, the discharge excitation technology now generally uses laser excitation using AC discharge of capacity coupling type. Its representative example is silent discharge (SD) excitation. This is a system to excite laser by applying high voltages with as high frequency as 100 kHz to 1 MHz across a pair of electrodes covered with a dielectric material. The system maintains stability in discharge even if power supply voltage amplitude is modulated, and easily provides pulse outputs. Discharge excitation for diffusion cooled type CO2 laser generates a discharge in a gap with a gap length of about 2 mm, and can perform gas cooling by means of thermal conduction of gas, whereas a compact resonator can be fabricated. A resonator for the diffusion cooled type CO2 laser eliminates gas circulation and cooling systems, hence the device can be made more compact. A report has been given that several of these compact resonators were combined, from which a laser output of 85W was obtained by using RF discharge of 2kW. 43 refs., 21 figs.

  7. Laser scar revision: comparison of CO2 laser vaporization with and without simultaneous pulsed dye laser treatment. (United States)

    Alster, T S; Lewis, A B; Rosenbach, A


    Over the past decade, the 585-nm pulsed dye laser (PDL) has been used successfully to treat a variety of cutaneous vascular lesions as well as hypertrophic scars. Laser scar revision has been revolutionized by the recent development of high-energy, pulsed carbon dioxide (CO2) laser systems. These new CO2 lasers allow controlled vaporization of thin layers of skin while minimizing damage to surrounding dermal structures. To determine the effect of a high-energy, pulsed CO2 laser alone and in combination with a 585-nm PDL on nonerythematous hypertrophic scars. Twenty patients with nonerythematous hypertrophic scars were treated with a high-energy, pulsed CO2 laser. One-half of each scar was additionally treated with the 585-nm PDL laser. Sequential clinical and photographic analyses were performed independently by two blinded assessors. In addition, erythema reflectance spectrometry measurements were obtained from the scars before and at regular postoperative intervals. Global assessment scores and erythema spectrometry measurements were significantly improved after laser treatment. Combination CO2 and PDL laser treatment resulted in more significant improvement than CO2 laser irradiation alone. Concomitant use of the high-energy, pulsed CO2 and PDL laser systems was superior to CO2 laser vaporization alone for revision of nonerythematous hypertrophic scars. Once again, the vascular specificity of the 585-nm PDL has been linked to improvement in hypertrophic scar tissue.

  8. Ablation of Liquids for Laser Propulsion with TEA CO2 Laser

    National Research Council Canada - National Science Library

    Sinko, John; Kodgis, Lisa; Porter, Simon; Sterling, Enrique; Lin, Jun; Pakhomov, Andrew V; Larson, C. W; Mead, Jr, Franklin B


    .... A Transversely Excited at Atmospheric pressure (TEA) CO2 laser operated at 10.6 micro-m, 300 ns pulse width, and 9 J pulse energy was used to ablate liquids contained in various aluminum and glass vessels...

  9. Ablation of Liquids for Laser Propulsion With TEA CO2 Laser

    National Research Council Canada - National Science Library

    Sinko, John; Kodgis, Lisa; Porter, Simon; Sterling, Enrique; Lin, Jun; Pakhomov, Andrew V; Larson, C. W; Mead, Jr., Franklin B


    .... A Transversely Excited at Atmospheric pressure (TEA) CO2 laser operated at 10.6 um, 300 ns pulse width, and 9 J pulse energy was used to ablate liquids contained in various aluminum and glass vessels...

  10. Space-Qualifiable High Reliability Frequency-Stabilized CW Laser Source Project (United States)

    National Aeronautics and Space Administration — We propose the SBIR Phase II effort to develop and space-qualify a 1.06 micron high reliability frequency-stabilized CW laser source that fully satisfies the...

  11. Space-Qualifiable High Reliability Frequency-Stabilized CW Laser Source Project (United States)

    National Aeronautics and Space Administration — We propose the development and space qualification of a high reliability frequency-stabilized CW laser source at 1064 nm wavelength region to satisfy the...

  12. A comparative evaluation: Oral leukoplakia surgical management using diode laser, CO2 laser, and cryosurgery. (United States)

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


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

  13. Design and optimisation of a pulsed CO2 laser for laser ultrasonics

    CSIR Research Space (South Africa)

    Forbes, A


    Full Text Available Slide 2 © CSIR 2006 Contents • Laser ultrasonics What is it, and how does it work? • Optimising the parameters Choices and consequences • Laser chemistry A physicists approach to chemistry • Discharge... fraction 0.2 0.4 0.6 0.8 1 e H n o i t c a r f Laser chemistry Impact of gas mix on laser chemistry Slide 10 © CSIR 2006 36 kV Heat Exchanger 2 CO2 2 CO + O2 2 CO2 2 CO + O2 Problem statement Slide...

  14. Modelling and experimental study of temperature profiles in cw laser diode bars (United States)

    Bezotosnyi, V. V.; Gordeev, V. P.; Krokhin, O. N.; Mikaelyan, G. T.; Oleshchenko, V. A.; Pevtsov, V. F.; Popov, Yu M.; Cheshev, E. A.


    Three-dimensional simulation is used to theoretically assess temperature profiles in proposed 10-mm-wide cw laser diode bars packaged in a standard heat spreader of the C - S mount type with the aim of raising their reliable cw output power. We obtain calculated temperature differences across the emitting aperture and along the cavity. Using experimental laser bar samples with up to 60 W of cw output power, the emission spectra of individual clusters are measured at different pump currents. We compare and discuss the simulation results and experimental data.

  15. Effect Of Laser CO2 Parameters In Marking Of Glass

    International Nuclear Information System (INIS)

    Khanafi-Benghalem, Nafissa; Boudoukha, Hassina; Benghalem, Kamel


    Currently many techniques of marking are exploited in a great number of sectors, on various materials (cardboard, textile, wood, leather, plastic, metal, ceramics and glass). The printing is done on supports of great or small dimension for all geometrical forms (plane, round, conical and ovalised). We can print colour as much than we wish. The marking technology for the identification of the glass parts knows a remarkable development carried by the new needs for the industrialists using transparent materials such as the optical, chemical, pharmaceutical sectors, the luxury and drink industries or publicity and decoration (neon signs, advertising mirrors). The objective of our work consists particularly in engraving on glass the measurement scales forming a whole of ordered graduation which the goal is to carry out reading systems of measuring apparatus about 1/10 μm of precision. We used as tool for marking the laser CO 2 . Our choice is justified by the flexibility of the laser, the permanent lifespan of the graduations carried out and the guarantee of the facility of reading incidentally the precision and the accuracy of the measuring apparatus. The study parameters of the laser beam are the velocity (400, 600, 800, 1000 m/s.), the power (25, 75 and 80% of 25W) and the numbers pass (one, two and three pass). The optical observations results obtained suggest that the highest and the average power used remain the favourable parameters for the quality of the graduations carried out.

  16. CO2 Laser Cutting of Hot Stamping Boron Steel Sheets

    Directory of Open Access Journals (Sweden)

    Pasquale Russo Spena


    Full Text Available This study investigates the quality of CO2 laser cutting of hot stamping boron steel sheets that are employed in the fabrication of automotive body-in-white. For this purpose, experimental laser cutting tests were conducted on 1.2 mm sheets at varying levels of laser power, cutting speed, and oxygen pressure. The resulting quality of cut edges was evaluated in terms of perpendicularity tolerance, surface irregularity, kerf width, heat affected zone, and dross extension. Experimental tests were based on a L9(34 orthogonal array design, with the effects of the process parameters on the quality responses being determined by means of a statistical analysis of variance (ANOVA. Quadratic mathematical models were developed to determine the relationships between the cutting parameters and the quality responses. Finally, a routine based on an optimization criterion was employed to predict the optimal setting of cutting factors and its effect on the quality responses. A confirmation experiment was conducted to verify the appropriateness of the optimization routine. The results show that all of the examined process parameters have a key role in determining the cut quality of hot stamping boron steel sheets, with cutting speed and their interactions having the most influencing effects. Particularly, interactions can have an opposite behavior for different levels of the process parameters.

  17. Effect Of Laser CO2 Parameters In Marking Of Glass (United States)

    Khanafi-Benghalem, Nafissa; Benghalem, Kamel; Boudoukha, Hassina


    Currently many techniques of marking are exploited in a great number of sectors, on various materials (cardboard, textile, wood, leather, plastic, metal, ceramics and glass). The printing is done on supports of great or small dimension for all geometrical forms (plane, round, conical and ovalised). We can print colour as much than we wish. The marking technology for the identification of the glass parts knows a remarkable development carried by the new needs for the industrialists using transparent materials such as the optical, chemical, pharmaceutical sectors, the luxury and drink industries or publicity and decoration (neon signs, advertising mirrors). The objective of our work consists particularly in engraving on glass the measurement scales forming a whole of ordered graduation which the goal is to carry out reading systems of measuring apparatus about 1/10 μm of precision. We used as tool for marking the laser CO2. Our choice is justified by the flexibility of the laser, the permanent lifespan of the graduations carried out and the guarantee of the facility of reading incidentally the precision and the accuracy of the measuring apparatus. The study parameters of the laser beam are the velocity (400, 600, 800, 1000 m/s.), the power (25, 75 and 80% of 25W) and the numbers pass (one, two and three pass). The optical observations results obtained suggest that the highest and the average power used remain the favourable parameters for the quality of the graduations carried out.

  18. Flexible CO2 laser fiber: first look at the learning curve required in gynecological laparoscopy training. (United States)

    Vanni, Valeria S; Ottolina, Jessica; Candotti, Giorgio; Castellano, Laura M; Tandoi, Iacopo; DE Stefano, Francesca; Poppi, Giorgia; Ferrari, Stefano; Candiani, Massimo


    The advent of flexible CO2 laser fiber to gynecology arena might represent a turning point in the use of laser energy on a large-scale basis in gynecological surgery. However, there might be some concerns regarding the degree of surgical skills required to use the flexible system. The purpose of our study is to evaluate whether flexible CO2 laser fiber is technically accessible. Fourteen residents in Obstetrics and Gynecology without surgical experience attending laparoscopic box training with both flexible CO2 laser fiber and traditional line-of-sight CO2 laser using Lumenis AcuPulse Duo CO2 laser (Lumenis, Yokne'am Illit, Israel) were prospectively enrolled. Participants were tested at sequential time points on specific surgical tasks and results obtained with the flexible CO2 laser fiber and the traditional line-of-sight CO2 laser were compared. Results were compared by means of paired t-test and a two-tailed P value flexible fiber and line-of-sight CO2 laser. At the end of training, significant improvement in surgical skills was obtained for both techniques, with a statistically significant higher grading for flexible fiber CO2 laser compared to line-of-sight CO2 laser. Our study found that residents without surgical experience show better skills with the flexible CO2 laser fiber delivery system compared to the standard line-of-sight CO2 laser system after a two-month training period with gynecological laparoscopic box. According to our results, flexible CO2 laser fiber delivery system is technically accessible and holds a potential in gynecological surgery.

  19. A CO2 Laser Thomson Scattering Diagnostic For The Measurement Of Fusion Product Alpha Particles (United States)

    Richards, R. K.; Bennett, C. A.; Fletcher, L. K.; Hunter, H. T.; Hutchinson, D. P.


    A Thomson scattering diagnostic for measuring the alpha particle velocity distribution is described. Calculations of scattering are made for a CIT type plasma using available CO2 laser and heterodyne technology. Tests of a long pulse CO2 laser, multichannel heterodyne detector, and an absorption cell for stray laser radiation are presented.

  20. Impact of Error in Atmospheric State on Column CO2 Retrievals from a Laser CO2 Sounder (United States)

    Mao, J.; Ramanathan, A. K.; Abshire, J. B.; Kawa, S. R.


    NASA Goddard is developing an integrated-path, differential absorption (IPDA) lidar approach to measure global atmospheric column CO2 concentrations from space as a candidate for NASA's Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission. This pulsed laser approach uses a step-locked laser diode source and a high-efficiency detector to measure atmospheric column CO2 absorption at multiple wavelengths across a CO2 line centered at 1572.335 nm with minimum temperature sensitivity. Atmospheric states from a global numerical forecast and data assimilation model are used as ancillary data to produce the best retrievals of column-averaged CO2 mixing ratio with regards to dry air. Retrieval error, both bias and random error, depends on uncertainties of atmospheric states for atmospheric radiative transfer calculations that are then used to fit measured CO2 absorption line shape for retrievals. Temperature data uncertainty, for example, can modify air density as well as absorption line intensity and line shape, which could cause significant error in radiative transfer calculations and then in column CO2mixing ratio retrievals. Uncertainty in atmospheric pressure and water vapor could also further increase retrieval error. We use atmospheric temperature profiles from Atmospheric InfraRed Sounder retrievals and the European Center for Medium range Weather Forecasting Model to assess temperature impact on spaceborne measurement of ASCENDS using our Goddard IPDA approach. We find the temperature differences produce a small impact on optical depth measurements on our CO2 line. Uncertainty in the atmospheric surface pressure could cause greater impact, implying a requirement for accurate dry air column density information in addition to laser ranging capability. We use data from the 2014 and 2016 ASCENDS airborne science campaigns to evaluate the atmospheric impact on our column CO2 concentration retrievals using the Goddard GEOS-5 meteorological

  1. Tunable CO2 laser system with subnanosecond-pulse-train output (United States)

    Kimura, W. D.


    A CO2 laser system has been demonstrated that generates a train of subnanosecond pulses tunable over the P and R branches of the CO2 laser spectrum at 9-11 μm. It utilizes optical free induction decay to generate a single 100-ps laser pulse from a tunable transverse-excited-atmospheric CO2 laser. This laser pulse is injection-seeded into a high-pressure CO2 oscillator whose output consists of a train of amplified 100-ps pulses with maximum pulse energy of 30 mJ, corresponding to a peak power of 300 MW. The 100-ps, tunable, infrared laser pulses are needed for a new technique to remotely detect atmospheric gaseous molecules, which relies on the train of CO2 laser pulses selectively exciting the target molecules whose presence is then revealed using a separate terahertz probe beam.

  2. Histological Ex Vivo Evaluation of Peri-Incisional Thermal Effect Created by a New-Generation CO2 Superpulsed Laser

    Directory of Open Access Journals (Sweden)

    G. Palaia


    Full Text Available The purpose of this study is the evaluation of the histological effects of a new-generation superpulsed CO2 laser through an “ex vivo” study. A CO2 (λ = 10,600 nm ultra-speed laser (SmartUS20D, DEKA, Florence, Italy has been used at different parameters from 2 to 4 watt in Continuous Wave (CW and Pulsed Wave (PW, 50 Hz to obtain 30 samples from pig cadaver tongues. All the specimens have been subdivided into 6 groups (from A to F and each group consisted of 5 samples. A final specimen has been taken by scalpel and used as control group. Histological analysis has been performed using an optical microscope (Leica DM 2000 at a magnification of ×40. Results showed that histological readability was optimal in all the samples. The thermal damage has been negligible in all the groups. Furthermore, the average of thermal damage was 0,095 mm in the epithelial, while it was 0.245 mm in the connective tissue. Statistical analysis using Graphpad Prism 5 software showed no significant differences among the groups. CO2 laser demonstrated a good surgical effectiveness provoking little peripheral damage onto the cut edges and allowing a safe histological diagnosis.

  3. High-quality laser cutting of stainless steel in inert gas atmosphere by ytterbium fibre and CO2 lasers

    International Nuclear Information System (INIS)

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


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

  4. SF6 laser remote sensing by CO2 laser DIAL lidar

    International Nuclear Information System (INIS)

    Parvin, P.; Basam, Z.; Zamanipour, Z.; Kariminezhad, H.; Boyook, N.; Borna, F.; Azari, T.; Eshragi, N.; Ataran, A.; Ghods Ahmad Zadeh, R.


    A DIAL system using tunable CO 2 laser has been demonstrated practically for remote sensing of SF 6 components in Mashad Shahid Motahhari Research Complex. Non toxic components of SF 6 as a rare isotope is studied to calibrate the lidar function in several conditions. The whole system enables us to detect ppm amounts of chemical gases as well as pollutants and poisonous species

  5. The results of CO2 laser surgery in patients with oral leukoplakia : a 25 year follow

    NARCIS (Netherlands)

    van der Hem, PS; Nauta, JM; van der Wal, JE; Roodenburg, JLN

    Oral leukoplakia, is an important premalignant Lesion of the oral mucosa. We treat this Lesion prophylactically with CO2 laser evaporation. In the period from 1976 to 2001, a group of 200 patients with 282 oral leukoplakias were treated by CO2 laser evaporation. In a follow up period of 1-219 months

  6. Reflection of Carbon Dioxide (CO 2 ) laser radiation from the theatre ...

    African Journals Online (AJOL)

    This work has investigated the power of both specular and diffusely reflected beams of CO2 laser radiation from metallic and non-metallic surfaces of an operating theatre including surgical instruments (specula) and different samples of wall paints in theatre 6 of the Aberdeen Royal Infirmary, U.K. where the CO2 laser ...

  7. Evaluation of catalyst for closed cycle operation of high energy pulsed CO2 lasers (United States)

    Rogowski, R. S.; Miller, I. M.; Wood, G.; Schryer, D. R.; Hess, R. V.; Upchurch, B. T.


    Several catalyst materials have been tested for efficiency of converting CO and O2 to CO2 for use in a high energy CO2 laser. The composition of the gas mixtures was monitored by mass spectrometry and gas chromatography. A copper/copper oxide catalyst and a platinum/tin oxide catalyst were used for closed cycle operation of a CO2 laser (0.7 joules/pulse), operating at 10 pulses/sec.

  8. High efficiency metal marking with CO2 laser and glass marking with excimer laser

    DEFF Research Database (Denmark)

    Bastue, Jens; Olsen, Flemmming Ove


    with a thoroughly tested ray-tracing model is presented and compared with experimental results. Special emphasis is put on two different applications namely marking in metal with TEA-CO2 laser and marking in glass with excimer laser. The results are evaluated on the basis of the achievable energy enhancement......Today, mask based laser materials processing and especially marking is widely used. However, the energy efficiency in such processes is very low [1].This paper gives a review of the results, that may be obtained using the energy enhancing technique [1]. Results of simulations performed...

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

    Directory of Open Access Journals (Sweden)

    Li-Li Zuo


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

  10. Analysis of lattice spots dazzling to CCD irradiated by CW laser (United States)

    Zhu, Rongzhen; Wang, Yanbin; Li, Hua; Ren, Guangsen; Hao, Yongwang


    The dazzling phenomena such as point saturation, line crosstalk present successively when laser irradiates on the CCD camera. We use CW laser at 532 nm and 1064 nm to irradiate the interline transfer area array CCD, CCD emerges lattice spots under the lens focusing. Based on geometrical optics, we use theoretical analysis and numerical simulation to study the mechanization of lattice spots. Laser jamming effects to the same CCD are different between 532 nm and 1064 nm. This is because the 532 nm laser diffracts with the chip, while 1064 nm laser interferences with its reflected light in the transmission process. Meanwhile, the mechanization of the ring surrounding the main spot is analyzed.

  11. Approach to compact terawatt CO2 laser system for particle acceleration

    International Nuclear Information System (INIS)

    Pogorelsky, I.V.; Kimura, W.D.; Fisher, C.H.; Kannari, F.


    A compact table-top 20-GW 50-ps CO 2 laser system is in operation for strong-field physics studies at the ATF. We propose scaling up of the picosecond CO 2 laser to a terawatt peak power level to meet the requirements of advanced laser accelerators. Computer modeling shows that a relatively compact single-beam picosecond CO 2 laser system with a high-pressure x-ray picosecond amplifier of a 10-cm aperture is potentially scalable to the ∼1-TW peak power level

  12. O uso do laser de CO2 na prevenção da carie dentaria


    Lidiany Karla Azevedo Rodrigues


    Resumo: A irradiação do esmalte dental com laser de CO2, especialmente se associada ao flúor, aumenta a resistência deste substrato ao desafio ácido. Deste modo, esta tese, constituída por 3 artigos, teve por objetivos: (1) descrever as características do laser de CO2 e revisar a literatura disponível enfocando seus efeitos na prevenção de cárie em esmalte e dentina, bem como discutir os efeitos deste mesmo laser quando associado ao flúor; (2) investigar, in vitro, o efeito do laser de CO2 (?...

  13. Independent tunability of the double-mode-locked cw dye laser.

    LENUS (Irish Health Repository)

    Bourkoff, E


    We report a new configuration that enables the double-mode-locked cw dye laser to be independently tunable. In addition, the output coupling at each of the two wavelengths can be independently specified. A series of oscillographs shows some interesting features unique to double mode locking and also shows the effects of varying the two cavity lengths with respect to each other.

  14. CO2 and Nd:YAP laser interaction with lithium disilicate and Zirconia dental ceramics: A preliminary study (United States)

    Rocca, Jean-Paul; Fornaini, Carlo; Brulat-Bouchard, Nathalie; Bassel Seif, Samy; Darque-Ceretti, Evelyne


    Lithium disilicate and Zirconia ceramics offer a high level of accuracy when used in prosthetic dentistry. Their bonding using different resins is highly dependent on micro-mechanical interlocking and adhesive chemical bonding. Investigation of the performances of high strength ceramics when their surface is modified for chemical and mechanical bonding is then required. The aim of this study is to investigate the possibility of using laser for surface treatment of different high strength CAD/CAM ceramics and thus to improve their mechanical and chemical properties. Thirty two CAD/CAM ceramic discs were divided into two different groups: lithium disilicate ceramics (IPS e.max CAD®, Ivoclar, Vivadent, Italy) and Zirconia ceramics (IPS e.max ZirCAD®, Ivoclar, Vivadent, Italy). The Laser surface treatment was performed by Carbon Dioxide laser (Dream Pulse Laser®, Daeshin Enterprise Corp., Korea) at 20 W, 25 W and 30 W CW and by Neodymium Yttrium Aluminum Perovskite laser (Nd:YAP Lokki®, Lobel Medical, France) at 10 W and 30 Hz. Physical modifications of the irradiated ceramic discs were observed by scanning electron microscopy (SEM) and chemically analyzed by Energy-Dispersive Spectroscopy (EDS). Surface wettability was tested using the water drop test and the crystalline structure was investigated using X-ray diffraction (XRD). The macroscopic observation showed a shinier structure in all the groups, while at the SEM observation only CO2 25 W and 30 W treated groups showed cracks and fissures. In the conditions of this study, CO2 laser and Nd:YAP laser with the parameters used create chemical and physical surface modifications of the ceramics, indicating the possibility of an improvement in adhesion of the tested ceramics.

  15. D2O laser pumped by an injection-locked CO2 laser for ion-temperature measurements

    International Nuclear Information System (INIS)

    Okada, Tatsuo; Ohga, Tetsuaki; Yokoo, Masakazu; Muraoka, Katsunori; Akazaki, Masanori.


    The cooperative Thomson scattering method is one of the various new techniques proposed for measuring the temperature of ions in nuclear fusion critical plasma, for which a high-performance FIR laser pumped by an injection-locked CO 2 laser is required. This report deals with D 2 O laser with a wavelength of 385 μm which is pumped by injection-locked single-mole TEA CO 2 laser composed of a driver laser and an output-stage laser. A small-sized automatic pre-ionization type laser is employed for the driver. The resonator of the driver laser consists of a plane grating of littrow arrangement and ZnSe plane output mirrors with reflection factor of 50 %. An aperture and ZnSe etalon are inserted in the resonator to produce single transverse- and longitudinal-mode oscillation, respectively. The output-stage laser is also of the automatic pre-ionization type. Theoretically, an injection power of 0.1 pW/mm 3 is required for a CO 2 laser. Single-mode oscillation of several hundred nW/mm 3 can be produced by the CO 2 laser used in this study. Tuning of the output-stage laser is easily controlled by the driver laser. High stability of the injection-locked operation is demonstrated. CO 2 laser beam is introduced into the D 2 O laser through a KCl window to excite D 2 O laser beam in the axial direction. Input and output characteristics of the D 2 O laser are shown. Also presented are typical pulse shapes from the D 2 O laser pumped by a free-running CO 2 laser pulse or by an injection-locked single-mode CO 2 laser pulse. (Nogami, K.)

  16. A high power CW Ho,Tm:GdVO4 laser (United States)

    Zhu, G. L.; Ju, Y. L.; Yao, B. Q.; Wang, Y. Z.


    In this paper, we report a 22.7 W continuous wave (CW) diode-pumped cryogenic Ho( at %), Tm(3 at %):GdVO4 laser. The pumping sources of Ho,Tm:GdVO4 laser are two fiber-coupled laser diodes with fiber core diameter of 0.4 mm, both of them can supply 42 W power laser operating near 802 nm. For input pump power of 64.7 W at 802.5 nm, the output power of 22.7 W in CW operation, optical-to-optical conversion efficiency of 35.1% at 2.05 μm has been attained. The M 2 factor was found to be 2.0 under an output power of 16.5 W.

  17. [Duration of middle ear ventilation after laser myringotomy with the CO2 laser otoscope Otoscan]. (United States)

    Sedlmaier, B; Jivanjee, A; Gutzler, R; Huscher, D; Jovanovic, S


    The most important principle in treating secretory otitis media (SOM) is ventilation of the tympanic cavity. CO2 laser myringotomy achieves this via a self-healing perforation whose diameter essentially determines the duration of transtympanic ventilation. In this study, laser myringotomy was performed with the CO2 laser otoscope Otoscan in a homogeneous patient collective comprising 81 children (159 ears) suffering from SOM. The tympanic intervention was combined with an adenoidectomy or a CO2 laser tonsillotomy and therefore performed under general insufflation anesthesia. In all ears, approximately 2 mm circular perforations were created in the lower anterior quadrants with a power of 12-15 W and a pulse duration of 180 ms. None of the children showed postoperative impairment of inner ear function. Otomicroscopic and videoendoscopic monitoring documented the healing process. The mean closure time was found to be 16.35 days (8-34 days). As a rule, an onion-skin-like membrane of keratinized material was seen in the former myringotomy perforations at the time of closure. At the follow-up 6 months later the laser myringotomy sites appeared normal and irritation-free. Two of the tympanic membranes (1.6%) examined showed atrophic scar formation, one (0.8%) a perforation with a diameter of 0.5 mm. In 19 ears (14.7%) there was a recurrence of SOM within the observation period. Laser myringotomy competes with ventilation tube insertion in the treatment of SOM. It may be an useful alternative in the surgical management of secretory otitis media.

  18. Comparative study of upper lip frenectomy with the CO2 laser versus the Er, Cr: YSGG laser (United States)

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


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

  19. Nanographene oxide as a switch for CW/pulsed NIR laser triggered drug release from liposomes. (United States)

    Sahu, Abhishek; Kim, Manse; Ryu, Jooyeon; Son, Joon-Gon; Lee, Eunji; Noh, Do Young; Tae, Giyoong


    The application of pulsed and continuous wave (CW) lasers in nanomedicine has increased significantly over the last decade. Near infrared (NIR) lasers can be used for the precise control of drug release at the target site in a non-invasive manner. In this study, we have prepared nanographene oxide (nGO, size ~40nm) integrated liposomes (size ~900nm). The nGOs were not simply adsorbed onto the liposome surface but was embedded inside the liposomes as characterized by cryo-TEM, selected area electron diffraction (SAED), and fluorescence quenching studies. The embedded nGOs could act as a molecular switch for NIR light controlled drug release from the liposomes. Calcein was encapsulated into the liposome as a model drug to evaluate the efficiency of light controlled release. An on-demand pulsatile drug release was achieved by irradiation of CW/pulsed NIR lasers into the nGO-liposome suspension. Triggering with a pulsed laser resulted in larger release of calcein with a minimal temperature increase (~2°C) of the liposome solution, compared to lower release rate and a significant temperature increase (~8°C) by a CW laser with the same light energy, suggesting two separate mechanisms and different potential applications depending on the laser type. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. A new frontier in CO2 flux measurements using a highly portable DIAL laser system (United States)

    Queiβer, Manuel; Granieri, Domenico; Burton, Mike


    Volcanic CO2 emissions play a key role in the geological carbon cycle, and monitoring of volcanic CO2 fluxes helps to forecast eruptions. The quantification of CO2 fluxes is challenging due to rapid dilution of magmatic CO2 in CO2-rich ambient air and the diffuse nature of many emissions, leading to large uncertainties in the global magmatic CO2 flux inventory. Here, we report measurements using a new DIAL laser remote sensing system for volcanic CO2 (CO2DIAL). Two sites in the volcanic zone of Campi Flegrei (Italy) were scanned, yielding CO2 path-amount profiles used to compute fluxes. Our results reveal a relatively high CO2 flux from Campi Flegrei, consistent with an increasing trend. Unlike previous methods, the CO2DIAL is able to measure integrated CO2 path-amounts at distances up to 2000 m using virtually any solid surface as a reflector, whilst also being highly portable. This opens a new frontier in quantification of geological and anthropogenic CO2 fluxes. PMID:27652775

  1. Catalytic Oxidation of CO for Closed-Cycle CO2 Lasers (United States)

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


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

  2. Novel method to sample very high power CO2 lasers: II Continuing Studies (United States)

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


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

  3. Longitudinally excited CO2 laser with short laser pulse operating at high repetition rate (United States)

    Li, Jianhui; Uno, Kazuyuki; Akitsu, Tetsuya; Jitsuno, Takahisa


    A short-pulse longitudinally excited CO2 laser operating at a high repetition rate was developed. The discharge tube was made of a 45 cm-long or 60 cm-long dielectric tube with an inner diameter of 16 mm and two metallic electrodes at the ends of the tube. The optical cavity was formed by a ZnSe output coupler with a reflectivity of 85% and a high-reflection mirror. Mixed gas (CO2:N2:He = 1:1:2) was flowed into the discharge tube. A high voltage of about 33 kV with a rise time of about 200 ns was applied to the discharge tube. At a repetition rate of 300 Hz and a gas pressure of 3.4 kPa, the 45 cm-long discharge tube produced a short laser pulse with a laser pulse energy of 17.5 mJ, a spike pulse energy of 0.2 mJ, a spike width of 153 ns, and a pulse tail length of 90 μs. The output power was 5.3 W. The laser pulse waveform did not depend on the repetition rate, but the laser beam profile did. At a low repetition rate of less than 50 Hz, the laser beam had a doughnut-like shape. However, at a high repetition rate of more than 150 Hz, the discharge concentrated at the center of the discharge tube, and the intensity at the center of the laser beam was higher. The laser beam profile depended on the distribution of the discharge. An output power of 7.0 W was achieved by using the 60 cm-long tube.

  4. A comparative study of pulsed Nd:YAG and CO2 laser effect on cardiovascular tissue


    Yova, D.; Papadakis, E.; Kassis, K.; Agapitos, E.; Kavantzas, N.; Koutsouris, D.; Serafetinidis, A.


    Percutaneous laser angioplasty is receiving increasing attention, as laser ablation of atheromatous plaque presents advantages to direct surgery or balloon angioplasty. One of the main prerequisites of using powerful pulsed lasers in angioplasty is the optimum choice of the irradiation parameters (the wavelength, the pulse shape and duration, the energy parameters e.t.c.). Infrared lasers have numerous applications in surgery. Among them the pulsed CO2 laser emitting at 10.6 µm and the pulsed...

  5. Direct acceleration of electrons by a CO2 laser in a curved plasma waveguide


    Yi, Longqing; Pukhov, Alexander; Shen, Baifei


    Laser plasma interaction with micro-engineered targets at relativistic intensities has been greatly promoted by recent progress in the high contrast lasers and the manufacture of advanced micro- and nano-structures. This opens new possibilities for the physics of laser-matter interaction. Here we propose a novel approach that leverages the advantages of high-pressure CO$_{2}$ laser, laser-waveguide interaction, as well as micro-engineered plasma structure to accelerate electrons to peak energ...

  6. A DC excited waveguide multibeam CO2 laser using high frequency ...

    Indian Academy of Sciences (India)

    Maximum 170 W output power is obtained with all beams operating in EH11 waveguide mode. The specific power of 28 W/m is much higher as compared to similar AC excited waveguide multibeam CO2 lasers. Theoretical analysis shows that all resonators of this laser will support only EH11 mode. This laser is successfully ...

  7. Benefits of cryogenic cooling on the operation of a pulsed CO2 laser

    Indian Academy of Sciences (India)


    Jan 5, 2014 ... Abstract. The paper presents results of a theoretical model of a pulsed electron beam controlled. CO2 laser (EBCL) to investigate the effect of cooling on the laser gas mixture. It is shown that cryogenic cooling can significantly improve the performance of the laser. The efficiency of an. EBCL improved from ...

  8. Benefits of cryogenic cooling on the operation of a pulsed CO2 laser

    Indian Academy of Sciences (India)


    Jan 5, 2014 ... The paper presents results of a theoretical model of a pulsed electron beam controlled CO2 laser (EBCL) to investigate the effect of cooling on the laser gas mixture. It is shown that cryogenic cooling can significantly improve the performance of the laser. The efficiency of an EBCL improved from 20% to ...

  9. Effect of the CO2 milliwatt laser on tensile strength of microsutures

    NARCIS (Netherlands)

    Menovsky, T.; Beek, J. F.; van Gemert, M. J.


    Laser-assisted tissue repair is often accompanied by a high dehiscence rate, which may be due to alterations in suture material after laser exposure. The goal of this study was to investigate the effect of CO2 laser irradiation on the tensile strength of microsurgical suture material. 10-0 nylon and

  10. Aesthetic skin resurfacing with the high-energy ultrapulsed CO2 laser. (United States)

    Weinstein, C; Roberts, T L


    CO2 laser resurfacing, using the new generation high-energy output pulsed lasers, provides a highly accurate method of resurfacing and rejuvenating facial skin. Its applications are widespread and well accepted by the general population (Color Figs. 3 to 8). Complications may occur, which may be minimized through adequate laser training and appreciation of the mechanisms of skin healing.

  11. Effect of surface-breakdown plasma on metal drilling by pulsed CO2-laser radiation (United States)

    Arutiunian, P. V.; Baranov, V. Iu.; Bobkov, I. V.; Bol'Shakov, L. A.; Dolgov, V. A.


    The effect of low-threshold surface breakdown produced by short (5-microsec) CO2-laser pulses on the metal drilling process is investigated. Data on the interaction of metals with laser pulses having the same duration but different shape are shown to be different. The effect of the ambient atmospheric pressure on the laser drilling process is investigated.

  12. First lasing of the Darmstadt cw free electron laser

    CERN Document Server

    Brunken, M; Eichhorn, R; Genz, H; Gräf, H D; Loos, H; Richter, A; Schweizer, B; Stascheck, A; Wesp, T


    The Darmstadt CW FEL designed for wavelengths between 3 and 10 mu m driven by the superconducting electron accelerator S-DALINAC first lased on December 1st, 1996 and has operated thereafter successfully in the wavelength region between 6.6 and 7.8 mu m. The pulsed electron beam employed had a micro pulse length of about 2ps, with a repetition rate of 10 MHz and a peak current of 2.7 A while its energy was varied between 29.6 and 31.5 MeV. A wedged pole hybrid undulator, with 80 periods each of 0.032 m length and a magnetic field strength of 0.15-0.4T, was located in between a 15.01 m long optical cavity equipped with two high reflectivity (99.8) mirrors of 0.05 m diameter. Due to the low beam current special care with respect to the electron and optical beam properties was necessary to meet the stringent conditions in order to reach a minute small signal gain of at least a few percent resulting in amplification. Saturation was obtained after about 2000 repetitions of the photon pulse inside the cavity. The D...

  13. Material characterization with top-hat cw laser induced photothermal techniques: A short review

    International Nuclear Information System (INIS)

    Astrath, N G C; Shen, J; Astrath, F B G; Zhou, J; Baesso, M L; Malacarne, L C; Pedreira, P R B; Bento, A C


    In this work, we present a short review of the recent development of the theoretical models for top-hat cw laser induced spectroscopies of thermal lens and thermal mirror. With the same probe and top-hat excitation lasers, an apparatus is set up to concurrently measure both thermal lens and thermal mirror effects of transparent samples. With the theoretical models and the experimental apparatus, not only optical and thermal properties are measured, but also the fluorescence quantum coefficient and the temperature coefficient of the optical path length of a fluorescent sample are simultaneously determined with no need of any reference sample. Mechanical properties also could be measured. Opaque samples are also studied using top-hat cw laser thermal mirror and top-hat photothermal deflection techniques to determine thermal properties (e.g., thermal conductivity and unit volume specific heat). This work shows that the combined top-hat cw laser photothermal techniques are useful for nondestructive evaluation of both transparent and opaque samples with a less expensive non-TEM 00 Gaussian laser.

  14. Antibacterial and Odontogenesis Efficacy of Mineral Trioxide Aggregate Combined with CO2 Laser Treatment. (United States)

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


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

  15. CO2 laser pulse switching by optically excited semiconductors

    International Nuclear Information System (INIS)

    Silva, V.L. da.


    The construction and the study of a semi-conductor optical switch used for generating short infrared pulses and to analyse the semiconductor characteristics, are presented. The switch response time depends on semiconductor and control laser characteristics. The results obtained using a Ge switch controlled by N 2 , NdYag and Dye lasers are presented. The response time was 50 ns limited by Ge recombination time. The reflectivity increased from 7% to 59% using N 2 laser to control the switch. A simple model for semiconductor optical properties that explain very well the experimental results, is also presented. (author) [pt

  16. Terawatt Picosecond CO2 Laser Technology for High Energy Physics Applications

    International Nuclear Information System (INIS)

    Pogorelsky, I. V.


    Demonstration of ultra-high acceleration gradients in the SM LWFA experiments put a next objective for the laser accelerator development to achieve a low-emittance monochromatic acceleration over extended interaction distances. The emerging picosecond terawatt (ps-TW) CO 2 laser technology helps to meet this strategic goal. Among the considered examples are: the staged electron laser accelerator (STELLA) experiment, which is being conducted at the Brookhaven ATF, and the plasma-channeled LWFA. The long-wavelength and high average power capabilities of CO 2 lasers maybe utilized also for generation of intense x-ray and gamma radiation through Compton back-scattering of the laser beams off relativistic electrons. We discuss applications of ps-TW CO 2 lasers for a tentative γ-γ (or γ-lepton) collider and generation of polarized positron beams

  17. Fiber optically guided CO2 laser myringotomy through an otoscope: animal experimentation (United States)

    DeRowe, Ari; Ophir, Dov; Katzir, Abraham


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

  18. Advanced concept of 100 kJ CO2 laser module for reactor laser

    International Nuclear Information System (INIS)

    Nakai, S.; Matoba, M.; Fujita, H.; Kawamura, Y.; Daido, H.


    The design study of 100 kJ CO 2 laser module for inertial fusion confinement is in progress. The basic requirement for the design of a 100 kJ laser is that the structure should be simple enough so as to be one module which can be compiled to set up a 1 MJ system. The requirements imposed on the design are the single gain medium to extract 100 kJ, the multi-pass amplification to achieve high efficiency, laser beam passing the gain medium many times, the possibility to preserve the arbitrary angle of beam injection, and the possibility of construction based on the established or tractable techniques. The gain medium of cylindrical shape was adopted to preserve all directional access with equal configuration. Demonstration experiments are planned to find out the optimized condition regarding to the vibrational relaxation, the time interval of each passage of a laser pulse, gas mixture and pressure, and pumping condition. The optical design of one beam for a 100 kJ test module is presented. This optical design named PENTAGONAL 10 has the following features; compact optics, high parasitic oscillation threshold, and the same intervals of multiple passing for energy extraction with four beams. The laser is an electron beam (E-beam)-controlled discharge laser. An electric power source and feed through were also studied. The construction of a 100 kJ laser system will be possible with the conventional techniques. (Kato, T.)

  19. Influence of laser-supported detonation waves on metal drilling with pulsed CO2 lasers

    International Nuclear Information System (INIS)

    Stuermer, E.; von Allmen, M.


    Drilling of highly reflective metals in an ambient atmosphere with single TEA-CO 2 -laser pulses of fluences between 300 and 6000 J/cm 2 is reported. The drilling process was investigated by measuring the time-resolved laser power reflected specularly from the targets during the interaction and by analyzing the craters produced. Experiments were performed in ambient air, argon, and helium. Target damage was found to be strongly influenced by a laser-supported detonation (LSD) wave in the ambient gas. If the laser fluence exceeded a material-dependent damage threshold (copper: 300 J/cm 2 ), drilling occurred, but the efficiency was inversely related to the duration of the LSD wave. Efficient material removal is possible if the LSD wave can be dissipated within a small fraction of the laser pulse duration. This was achieved by small-F-number focusing of TEM 00 laser pulses of 5-μs duration. Replacing the ambient air at the target by a gas of lower density results in a further significant reduction of LSD-wave lifetime, and a correlated increase of the drilling yield. On copper targets a maximum drilling yield of 10 -5 cm 3 /J was observed in ambient helium at a laser fluence of 1 kJ/cm 2

  20. Optical trapping assembling of clusters and nanoparticles in solution by CW and femtosecond lasers

    KAUST Repository

    Masuhara, Hiroshi


    Laser trapping of molecular systems in solution is classified into three cases: JUST TRAPPING, EXTENDED TRAPPING, and NUCLEATION and GROWTH. The nucleation in amino acid solutions depends on where the 1064-nm CW trapping laser is focused, and crystallization and liquid–liquid phase separation are induced by laser trapping at the solution/air surface and the solution/glass interface, respectively. Laser trapping crystallization is achieved even in unsaturated solution, on which unique controls of crystallization are made possible. Crystal size is arbitrarily controlled by tuning laser power for a plate-like anhydrous crystal of l-phenylalanine. The α- or γ-crystal polymorph of glycine is selectively prepared by changing laser power and polarization. Further efficient trapping of nanoparticles and their following ejection induced by femtosecond laser pulses are introduced as unique trapping phenomena and finally future perspective is presented.

  1. Use of CO2 laser in pit and fissure caries prevention: clinical evaluation (United States)

    Brugnera, Aldo, Jr.; Rosso, Naomi; Duarte, Danilo; Guedes Pinto, Antonio C.; Genovese, Walter J.


    In this four-year follow up in vivo controlled study, 112 human permanent first molars, from children between the ages of 6 and 11 years old were used to investigate the viability of the CO2 laser in promoting carie-free occlusal surfaces in permanent molars, as an isolated form of treatment or associated with conventional fissure sealants. The findings suggest that occlusal caries prevention only by means of CO2 laser irradiation is not effective; that the utilization of photo-activated sealants, as well as its association with CO2 laser, applied over the occlusal fissures, are effective means of preventing occlusal caries and that the application of CO2 laser over occlusal fissures, prior to the application of a photo-activated fissure sealant, improves the retention of the sealant.



    Marchetti, S.; Simili, R.; Giorgi, M.


    Large Helium -free emissions are obtained in two mini-TEA CO2 lasers , by using always a corona preionization, without additives, with a maximum energy density of 900 J/lt. deposited into the discharge

  3. Keyhole depth instability in case of CW CO2 laser beam welding of ...

    Indian Academy of Sciences (India)

    LBW) is essential to understand welding process and appearance of weld seam defects. The main cause of keyhole collapse is the instability in KH dynamics during the LBW process. This is mainly due to the surface tension forces associated with ...

  4. TEA CO2 laser machining of CFRP composite


    Salama, Adel; Li, Lin; Mativenga, Paul; Whitehead, David


    Carbon fibre-reinforced polymer (CFRP) composites have found wide applications in the aerospace, marine, sports and automotive industries owing to their lightweight and acceptable mechanical properties compared to the commonly used metallic materials. Machining of CFRP composites using lasers can be challenging due to inhomogeneity in the material properties and structures, which can lead to thermal damages during laser processing. In the previous studies, Nd:YAG, diode-pumped solid-state, CO...

  5. Fabrication of microlens and microlens array on polystyrene using CO 2 laser

    KAUST Repository

    Fan, Yiqiang


    This study presents a new process for fabricating microlens and microlens arrays directly on a surface of polystyrene using a CO2 laser. The working spot of the polystyrene is heated locally by a focused CO2 laser beam, which tends to have a hyperboloid profile due to the surface tension and can be used as a microlens. The microlenses with different dimensions were fabricated by changing the power of the laser beam. Microlens array was also fabricated with multiple scans of the laser beam on the polystyrene surface. © (2012) Trans Tech Publications, Switzerland.

  6. Rapidly tuning miniature transversely excited atmospheric-pressure CO2 laser. (United States)

    Qu, Yanchen; Ren, Deming; Hu, Xiaoyong; Liu, Fengmei; Zhao, Jingshan


    An experimental study of a rapidly tuning miniature transversely excited atmospheric-pressure CO2 laser is reported. To rapidly shift laser wavelengths over selected transitions in the 9-11 microm wavelength region, we have utilized a high-frequency stepping motor and a diffraction grating. The laser is highly automated with a monolithic microprocessor controlled laser line selection. For the achievement of stable laser output, a system of laser excitation with a voltage of 10 kV, providing effective surface corona preionization and allowing one to work at various gas pressures, is utilized. Laser operation at 59 emission lines of the CO2 molecule rotational transition is obtained and at 51 lines, the pulse energy of laser radiation exceeds 30 mJ. The system can be tuned between two different rotational lines spanning the wavelength range from 9.2 to 10.8 microm within 10 ms.

  7. A feasible procedure in dental practice: the treatment of oral dysplastic hyperkeratotic lesions of the oral cavity with the CO2 laser. (United States)

    Santos, Nicole R Silva; Aciole, Gilberth T S; Marchionni, Antonio M T; Soares, Luiz G P; dos Santos, Jean Nunes; Pinheiro, Antônio L B


    The aim of this work is to report some cases of surgical removal of hyperkeratotic lesions of the oral cavity with the CO(2) laser. Hyperkeratosis is an abnormal thickening of the stratum corneum caused by increased deposition of keratin, and its histopathologic features show wide variations. These changes are significant because they determine different biologic behavior. Several techniques are used to treat these lesions, including scalpel incision, electrosurgery, cryosurgery, photodynamic therapy, and some drugs. The use of surgical lasers has been proposed as an effective way of treating such lesions safely. The CO(2) laser is the most used laser on the oral cavity because of its affinity for water and high absorption by the oral mucosa. Several benefits of the use of the CO(2) laser are reported in the literature in regard to surgical procedures carried out on the oral cavity. All patients had histopathologic diagnosis of hyperkeratosis and mild epithelial dysplasia and were routinely prepared for surgery under local anesthesia. The surgical procedures were carried out by using a CO(2) laser (Sharplan 20 C; Laser Industries, Tel Aviv, Israel, λ10,600 nm, φ∼2 mm, CW/RSP). The beam was focused to delimit each lesion, and then lesions were excised, and the removed specimens were sent for histopathology. At the end of the surgery, the beam was used in a defocused manner to promote better hemostasis. Neither sutures nor dressings were used after the surgery. No medication but mouthwashes was prescribed to all patients in the postoperative period. The use of the CO(2) laser does not reduce the risk of relapses of the lesion, but it is an easy-to-use technique and results in both a quick surgical procedure and trouble-free postoperative period and may be safely used in dental practice.

  8. High Efficiency Mask Based Laser Materials Processing with TEA-CO2 - and Excimer Laser

    DEFF Research Database (Denmark)

    Bastue, Jens; Olsen, Flemmming Ove


    In general, mask based laser materials processing techniques suffer from a very low energy efficiency. We have developed a simple device called an energy enhancer, which is capable of increasing the energy efficiency of typical mask based laser materials processing systems. A short review of the ...... line marking with TEA-CO2 laser of high speed canning lines. The second one is manufactured for marking or microdrilling with excimer laser.......In general, mask based laser materials processing techniques suffer from a very low energy efficiency. We have developed a simple device called an energy enhancer, which is capable of increasing the energy efficiency of typical mask based laser materials processing systems. A short review...... of the most widely used applications of these systems is given and the potential advantages of the energy enhancer are discussed.The basic principle behind the energy enhancing technique is explained and two new energy enhancers are presented and evaluated. The first one is designed especially for single text...

  9. Laser Wakefield Acceleration Driven by a CO2 Laser (STELLA-LW) - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Wayne D


    The original goals of the Staged Electron Laser Acceleration – Laser Wakefield (STELLA-LW) program were to investigate two new methods for laser wakefield acceleration (LWFA). In pseudo-resonant LWFA (PR-LWFA), a laser pulse experiences nonlinear pulse steepening while traveling through the plasma. This steepening allows the laser pulse to generate wakefields even though the laser pulse length is too long for resonant LWFA to occur. For the conditions of this program, PR-LWFA requires a minimum laser peak power of 3 TW and a low plasma density (10^16 cm^-3). Seeded self-modulated LWFA (seeded SM-LWFA) combines LWFA with plasma wakefield acceleration (PWFA). An ultrashort (~100 fs) electron beam bunch acts as a seed in a plasma to form a wakefield via PWFA. This wakefield is subsequently amplified by the laser pulse through a self-modulated LWFA process. At least 1 TW laser power and, for a ~100-fs bunch, a plasma density ~10^17 cm^-3 are required. STELLA-LW was located on Beamline #1 at the Brookhaven National Laboratory (BNL) Accelerator Test Facility (ATF). The ATF TW CO2 laser served as the driving laser beam for both methods. For PR-LWFA, a single bunch was to probe the wakefield produced by the laser beam. For seeded SM-LWFA, the ATF linac would produce two bunches, where the first would be the seed and the second would be the witness. A chicane would compress the first bunch to enable it to generate wakefields via PWFA. The plasma source was a short-length, gas-filled capillary discharge with the laser beam tightly focused in the center of the capillary, i.e., no laser guiding was used, in order to obtain the needed laser intensity. During the course of the program, several major changes had to be made. First, the ATF could not complete the upgrade of the CO2 laser to the 3 TW peak power needed for the PR-LWFA experiment. Therefore, the PR-LWFA experiment had to be abandoned leaving only the seeded SM-LWFA experiment. Second, the ATF discovered that the

  10. Measurements of sulfur compounds in CO 2 by diode laser atomic absorption spectrometry (United States)

    Franzke, J.; Stancu, D. G.; Niemax, K.


    Two simple methods for the analysis of the total concentration of sulfur in CO 2 by diode laser atomic absorption spectrometry of excited, metastable sulfur atoms in a direct current discharge are presented. In the first method, the CO 2 sample gas is mixed with the plasma gas (Ar or He) while the second is based on reproducible measurements of the sulfur released from the walls in a helium discharge after being deposited as a result of operating the discharge in pure CO 2 sample gas. The detection limits obtained satisfy the requirements for the control of sulfur compounds in CO 2 used in the food and beverage industry.

  11. Development of a Pulsed 2-micron Laser Transmitter for CO2 Sensing from Space (United States)

    Singh, Upendra N.; Yu, Jirong; Bai, Yingxin; Petros, Mulugeta; Menzies, Robert T.


    NASA Langley Research Center (LaRC), in collaboration with NASA Jet Propulsion Laboratory (JPL), is engaged in the development and demonstration of a highly efficient, versatile, 2-micron pulsed laser that can be used in a pulsed Differential Absorption Lidar (DIAL)/Integrated Path Differential Absorption (IPDA) instrument to make precise, high-resolution CO2 measurements to investigate sources, sinks, and fluxes of CO2. This laser transmitter will feature performance characteristics needed for an ASCENDS system that will be capable of delivering the CO2 measurement precision required by the Earth Science Decadal Survey (DS).

  12. Gain kinetics of CO2 gasdynamic laser mixtures at high pressure. (United States)

    Christiansen, W. H.; Tsongas, G. A.


    Description of a combined analytical and experimental investigation of rapidly expanded CO2 laser mixtures. Study of the vibrational kinetics indicates that population inversions with high vibrational energy density can be produced at high pressures by utilizing low (starved) concentrations of CO2. Scaling laws for predicting the gain of starved systems are developed. A description is given of gain measurements carried out using a CO2 laser to probe the flow in a nozzle at the point where the Mach number is approximately four. Population inversions at static pressures as high as about 1 atm have been observed and found to be in reasonable agreement with predictions.

  13. Frequency Stabilization of DFB Laser Diodes at 1572 nm for Spaceborne Lidar Measurements of CO2 (United States)

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


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

  14. Birefringence and residual stress induced by CO2 laser mitigation of damage growth in fused silica (United States)

    Gallais, L.; Cormont, P.; Rullier, J. L.


    We investigate the residual stress field created near mitigated sites and its influence on the efficiency on the CO2 laser mitigation of damage growth process. A numerical model of CO2 laser interaction with fused silica is developed that take into account laser energy absorption, heat transfer, thermally-induced stress and birefringence. Specific photoelastic methods are developed to characterize the residual stress near mitigated sites in fused silica samples. The stress distribution and quantitative values of stress levels are obtained for sites treated with the CO2 laser in various conditions of energy deposition (beam size, pulse duration, incident power). The results obtained also show that the presence of birefringence/residual stress around the mitigated sites has a critical effect on their laser damage resistance.

  15. CO2 laser interaction with magnetically confined plasmas. Annual report

    International Nuclear Information System (INIS)

    Vlases, G.C.; Pietrzyk, Z.A.


    The experimental program involves two basic experimental configurations termed the slow (or steady) solenoid, and the fast solenoid. In the former, the field is essentially steady during the experiment lifetime, the gas (plasma) remains in contact with the wall, and all the heating is done by the laser. In the fast solenoid, the field rises on a timescale comparable to the laser pulse length, removing the plasma from the wall, and contributing to the plasma energy content via compression work. In the slow solenoid, preionization is generally not used, and the laser both creates the plasma and heats it. In the fast solenoid, the preionization technique is relatively critical as it must create conditions leading to a true particle minimum on axis in order to insure favorable refraction of the laser beam (''trapping''). Substantial progress has been made in both experiments this year, particularly with respect to diagnostic capabilities. In addition, the theoretical effort has expanded considerably. Highlights of this year's program are listed and details are contained in the balance of the report

  16. Flexible CO2 Laser Fiber in the Pediatric Airway

    Directory of Open Access Journals (Sweden)

    Kimberly K. Caperton


    Full Text Available Objective. Our institution has been using a novel flexible laser fiber in pediatric surgical airway procedures, which has been quite successful. The purpose of this paper is to present our preliminary experience in the treatment of pediatric airway lesions using this laser technique. Methods. A case series reviewing 40 patients undergoing 95 laser procedures is reported. Indications included removal of suprastomal granulation tissue, removal of granulation after laryngotracheal reconstruction, subglottic and supraglottic stenoses, recurrent respiratory papillomas, subglottic hemangioma, laryngeal cleft, and left main stem bronchus stenosis. Procedures were performed via microdirect laryngoscopy and bronchoscopy. Results. No complications including postoperative glottic webs, concentric scar formation, or airway fires occurred in any of the patients (after the series was completed, we did experience an airway fire. It was a flash flame that was self-limited and caused no long-term tissue injury. Conclusions. The endoscopic application of a new flexible carbon dioxide laser fiber for management of pediatric airways lesions provides good outcomes in selected patients. Distal respiratory papillomas, subglottic stenosis, and granulation tissue are, in our experience, appropriate indications.

  17. Accelerator mass spectrometry 14C determination in CO2 produced from laser decomposition of aragonite. (United States)

    Rosenheim, Brad E; Thorrold, Simon R; Roberts, Mark L


    The determination of (14)C in aragonite (CaCO(3)) decomposed thermally to CO(2) using an yttrium-aluminum-garnet doped neodymium laser is reported. Laser decomposition accelerator mass spectrometry (LD-AMS) measurements reproduce AMS determinations of (14)C from the conventional reaction of aragonite with concentrated phosphoric acid. The lack of significant differences between these sets of measurements indicates that LD-AMS radiocarbon dating can overcome the significant fractionation that has been observed during stable isotope (C and O) laser decomposition analysis of different carbonate minerals. The laser regularly converted nearly 30% of material removed into CO(2) despite it being optimized for ablation, where laser energy breaks material apart rather than chemically altering it. These results illustrate promise for using laser decomposition on the front-end of AMS systems that directly measure CO(2) gas. The feasibility of such measurements depends on (1) the improvement of material removal and/or CO(2) generation efficiency of the laser decomposition system and (2) the ionization efficiency of AMS systems measuring continuously flowing CO(2).

  18. Fractional CO2lasers contribute to the treatment of stable non-segmental vitiligo. (United States)

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


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

  19. Isotopically selective RIMS of rare radionuclides by double-resonance excitation with cw lasers

    International Nuclear Information System (INIS)

    Bushaw, B.A.; Munley, J.T.


    Double-resonance, Resonance Ionization Mass Spectroscopy (RIMS) using two single-frequency dye lasers and a CO 2 laser for photoionization has been shown to be both extremely sensitive and highly selective. Measurements on the radioisotope 210 Pb have demonstrated optical selectivity in excess of 10 9 and detection limits of less than 1 femtogram

  20. Direct acceleration of electrons by a CO2 laser in a curved plasma waveguide

    CERN Document Server

    Yi, Longqing; Shen, Baifei


    Laser plasma interaction with micro-engineered targets at relativistic intensities has been greatly promoted by recent progress in the high contrast lasers and the manufacture of advanced micro- and nano-structures. This opens new possibilities for the physics of laser-matter interaction. Here we propose a novel approach that leverages the advantages of high-pressure CO 2 laser, laser-waveguide interaction, as well as micro-engineered plasma structure to accelerate electrons to peak energy greater than 1 GeV with narrow slice energy spread (~1%) and high overall efficiency. The acceleration gradient is 26 GV/m for a 1.3 TW CO2 laser system. The micro-bunching of a long electron beam leads to the generation of a chain of ultrashort electron bunches with the duration roughly equal to half-laser-cycle. These results open a way for developing a compact and economic electron source for diverse applications.

  1. Pseudoxanthoma Elasticum Treatment with Fractional CO2 Laser

    Directory of Open Access Journals (Sweden)

    Alessandra Grassi Salles, MD, PhD


    Full Text Available Summary: Pseudoxanthoma elasticum (PE is a rare genetic disease characterized by calcification and fragmentation of elastic fibers of the skin, retina, and cardiovascular system. We report a case of PE in which fractional carbon dioxide laser treatment was successfully used to achieve improvement of the cervical skin with 2-year follow-up, in a patient with Fitzpatrick skin type IV. After the fifth session, the patient presented with a local herpes infection. The postlaser reaction of the PE skin was similar to that of the normal skin, in terms of the duration of redness, pain, swelling, and duration of crusting. The overall cosmetic result was satisfactory, with improvement in skin texture, irregularity, volume, and distensibility. The herpetic infection reinforces the value of antiviral prophylaxis during laser treatment of extrafacial areas.

  2. Predicting gas decomposition in an industrialized pulsed CO2 laser

    CSIR Research Space (South Africa)

    Forbes, A


    Full Text Available , and then test this against experimental data. This is because rate laws must be determined from measurements of reaction rates, and cannot be deduced from reaction stoichiometry. The reader is refered to standard physical chemistry texts5 for further... if kd is not gas species dependent. 3. CATALYSTS PRESENT With catalysts present in the laser, the oxygen concentration stabilise quickly and at lower levels than in the case of no catalysts. Using the model already found for the discharge chemistry...

  3. CO2 TEA Laser-Enhanced Laser Ablation Molecular Isotopic Spectrometry (TELLAMIS) (United States)

    Brown, Staci R.; Akpovo, Charlemagne A.; Ford, Alan; Herbert, Kenley; Johnson, Lewis


    Recently, it has been shown that the relative abundance of isotopes in enriched materials can be determined via laser-induced breakdown spectroscopy (LIBS) in a technique known as laser-ablation molecular isotopic spectroscopy (LAMIS). The original LAMIS work has focused on single-pulse (SP) LIBS for the excitation. However, dual-pulse (DP) LIBS reduces shot-to-shot variation and can lower detection limits of an element by about an order of magnitude or more. It also has the potential to improve the accuracy of the determination of the relative abundances of isotopes in LAMIS by minimizing the signal-to-noise ratio. In this work, a DP-LIBS technique for improving LAMIS relative-abundance information from a sample is presented. The new technique, called (TEA) Transverse-Excited breakdown in Atmosphere Laser-Enhanced Laser Ablation Molecular Isotopic Spectrometry (TELLAMIS), uses a carbon dioxide (CO2) laser to increase the breakdown emission from LIBS in the LAMIS method. This technique is demonstrated on a collection of relative abundance isotopes of boron- 10 and boron-11 in varying concentrations in boric acid. Least-squares fitting to theoretical models are used to deduce plasma parameters and understand reproducibility of results. DTRA.

  4. Application Of CO2 Lasers To High Speed Blanking (United States)

    Grenier, L. E.


    While laser cutting of sheetmetal has attained wide acceptance in the automotive industry for the purposes of prototyping and very limited preproduction work, the production rates possible with currently available systems have precluded the use of this technique in a production environment. The device design to be described embodies a high speed X-Y positioner carrying a cutting head with limited Z-axis capability. This approach confers two main benefits, first, production rate is limited only by laser power, since the positioner technology selected will permit movement at rates up to 1.5 m/s (60 in/s), second, the use of a high speed non-contact surface follower to control the Z-axis movement reduces the need to clamp the workpiece rigidly to a precision reference surface. The realized reduction of the clamping requirement permits some latitude in the feed methods that can be employed, allowing the use of coil or sheet feeding as appropriate. The author will provide estimated production rates for the proposed design and demonstrate that a suitable choice of laser source and material feed will permit the production of parts at a rate and cost comparable to conventional blanking with the advantage of much greater flexibility and reduced retooling time.

  5. Adaptive metal mirror for high-power CO2 lasers (United States)

    Jarosch, Uwe-Klaus


    Spherical mirrors with a variable radius of curvature are used inside laser resonators as well as in the beam path between the laser and the workpiece. Commercially-available systems use piezoelectric actuators, or the pressure of the coolant, to deform the mirror surface. In both cases, the actuator and the cooling system influence each other. This interaction is avoided through the integration of the cooling system with the flexible mirror membrane. A multi- channel design leads to an optimized cooling effect, which is necessary for high power applications. The contour of the variable metal mirror depends on the mounting between the membrane and the mirror body and on the distribution of forces. Four cases of deformation can be distinguished for a circular elastic membrane. The realization of an adaptive metal mirror requires a technical compromise to be made. A mechanical construction is presented which combines an elastic hinge with the inlet and outlet of the coolant. For the deformation of the mirror membranes two actuators with different character of deformation are used. The superposition of the two deformations results in smaller deviations from the spherical surface shape than can be achieved using a single actuator. DC proportional magnets have been introduced as cheap and rigid actuators. The use of this adaptive mirror, either in a low pressure atmosphere of a gas laser resonator, or in an extra-cavity beam path is made possible through the use of a ventilation system.

  6. CO2 laser-inscribed low-cost, shortest-period long-period fibre ...

    Indian Academy of Sciences (India)


    Feb 7, 2014 ... that boron co-doping in the fibre lowers the fictive temperature of the core substantially, and so local heating of the fibre by CO2 laser radiation causes not only stress relaxation, but also glass structure changes in the core [6]. With a low laser irradiation power, index change occurs only in the core and the ...

  7. Third harmonic generation of CO2 laser radiation in AgGaSe2 crystal

    Indian Academy of Sciences (India)

    September 2000 physics pp. 405–412. Third harmonic generation of CO2 laser radiation in. AgGaSe2 crystal. GOPAL C BHAR, PATHIK KUMBHAKAR. ½. , D V SATYANARAYANA. ¾. ,. N S N BANERJEE. ¾. , U NUNDY. ¾ and C G CHAO. ¿. Laser Laboratory, Physics Department, Burdwan University, Burdwan 713 104, ...

  8. Third harmonic generation of CO2 laser radiation in AgGaSe2 crystal

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 55; Issue 3. Third harmonic generation of CO2 laser radiation in AgGaSe2 crystal ... Laser Laboratory, Physics Department, Burdwan University, Burdwan 713 104, India; Centre for Advanced Technology, Indore 452 013, India; Anhui Institute of Optics and Fine ...

  9. Acoustic waves in transversely excited atmospheric CO2 laser discharges: effect on performance and reduction techniques

    CSIR Research Space (South Africa)

    von Bergmann, HM


    Full Text Available Results are presented on the influence of acoustic waves on the performance of high-repetition-rate TEA CO2 lasers. It is shown that acoustic waves generated inside the laser cavity lead to nonuniform discharges, resulting in a deterioration...

  10. A compact spark pre-ionized pulser sustainer TE–CO2 laser

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    . The availability of lasers with long pulse duration and relatively high energy capability enhances the development of new ... In this paper we report on the generation of long optical pulses (7·15µs) from a compact and reliable TE–CO2 laser ...

  11. A compact spark pre-ionized pulser sustainer TE–CO2 laser

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Abstract. A compact spark pre-ionized pulser sustainer TE–CO2 laser that can produce an output energy of one joule with an overall efficiency of 12·4% is presented. Optical pulses have durations of 7·15µs FWHM. Here, the laser uses all solid-state excitation (ASSE) circuit and the discharge formed between two.

  12. Comparison of results with CO2 laser and traditional surgical treatment of stage I malignant melanoma

    International Nuclear Information System (INIS)

    Reali, U.M.; Donati, E.; Quercetani, R.; Ciardi, C.; Chiarugi, C.


    The follow-up data on 39 cases of stage I malignant melanoma treated with CO 2 laser are compared to those of an analogous group of cases treated by traditional surgical methods and selected for their clinical and pathologic similarities with the laser-treated group. The findings ware expressed in terms of tumor-free time and were evaluated by variance analysis. The data showed that traditional methods gave better results. CO 2 laser surgery requires longer headling time, which may have a negative effect on the course of the disease

  13. Influence of acoustic waves on TEA CO2 laser performance

    CSIR Research Space (South Africa)

    Von Bergmann, H


    Full Text Available 420 440 460 Laser Repetition Rate (Hz) En er gy J itt er (s td d ev % ) series circuit series circuit, random rep rate parallel circuit parallel circuit, random rep rate Figure 7: The parallel circuit shows much higher... sensitivity to the acoustic waves. Figure 7 shows data for a pre-ionisation circuit where all the energy passes through the pre-ionisation sparks prior to the discharge (series circuit), and for a circuit where the pre-ionisation is in parallel...

  14. Phase-locking of annular-combination CO2 laser (United States)

    Qi, Tingxiang; Chen, Mei; Zhang, Rongzhu; Xiao, Qianyi


    A new annular-combination resonator structure adopting the external-injection phase-locking technology is presented theoretically for that the beam quality of stable annular resonator is not satisfying. The phase-locking principle and feasibility are characterized by energy density of injection beam and coupling coefficient. Based on the diffraction theory, output mode of the resonator with phase-locking is deduced and simulated. Results also confirm that injection beam have a good control effect on output mode. The intensity distributions of output beam are studied briefly and indicate that this new resonator which is adaptable to annular gain media can produce high-power laser beam with high quality.

  15. Lichen amyloidosis successfully treated with fractional ablative laser CO2: A new alternative therapeutic. (United States)

    Korbi, Mouna; Akkari, Hayet; Soua, Yosra; Mohamed, Mariem; Youssef, Monia; Belhajdali, Hichem; Zili, Jameledine


    Lichen amyloidosis is a primary localized cutaneous amyloidosis. Different types of treatment have been used without complete resolution. Herein, we report a case of patient suffering from lichen amyloidosis successfully treated with fractional ablative laser CO 2 . He was a 59-year-old man diagnosed lichen amyloidosis localized on the legs 10 years ago. He was treated with topical corticosteroids without any improvement. Then, we started treating the affected area with CO 2 laser (limmer*) at a setting of 5-8 J/cm 2 and 8 mm laser spot size. A considerable improvement was noticed after the first session. A total healing was reported after four sessions. To the best of our knowledge, only 11 reported cases of lichen amyloidosis have been successfully treated with laser CO 2 . However, our clinical finding seems to be one of the best reported results.

  16. In situ testing of CO2 laser on dental pulp function: Effects on microcirculation

    Energy Technology Data Exchange (ETDEWEB)

    Friedman, S.; Liu, M.; Doerscher-Kim, J.K.; Kim, S. (Department of Endodontics, Hadassah-Hebrew University School of Dental Medicine, Jerusalem (Israel))


    The effect of CO2 laser irradiation on pulpal microcirculation was studied in cat canines. The enamel surfaces of 4 teeth were exposed with energy densities of 304-1440J/cm2, using either a handpiece or a microslad, with a focal spot of 0.21mm and 0.33mm respectively. Pulpal blood flow (PBF) before and following lasing was recorded through the intact tooth surface by a laser Doppler flowmeter. CO2 laser irradiation caused an increase in PBF, which was immediate and transient. The PBF increase was higher in a large pulp than in a small pulp, and it was inversely related to the focal spot size. These findings confirm that the dental pulp is thermally affected by CO2 lasing of the tooth surface, however, without extensive pulp coagulation. It is concluded that the effects of laser irradiation on the pulpal microcirculation may be studied in situ by means of the presented methodology.

  17. Spatial temperature distribution in human hairy and glabrous skin after infrared CO2 laser radiation. (United States)

    Frahm, Ken S; Andersen, Ole K; Arendt-Nielsen, Lars; Mørch, Carsten D


    CO2 lasers have been used for several decades as an experimental non-touching pain stimulator. The laser energy is absorbed by the water content in the most superficial layers of the skin. The deeper located nociceptors are activated by passive conduction of heat from superficial to deeper skin layers. In the current study, a 2D axial finite element model was developed and validated to describe the spatial temperature distribution in the skin after infrared CO2 laser stimulation. The geometry of the model was based on high resolution ultrasound scans. The simulations were compared to the subjective pain intensity ratings from 16 subjects and to the surface skin temperature distributions measured by an infrared camera. The stimulations were sensed significantly slower and less intense in glabrous skin than they were in hairy skin (MANOVA, p 0.90, p CO2 laser stimulation intensity, temperature levels and nociceptor activation.

  18. High quality electron bunch generation with CO2-laser-plasma interaction (United States)

    Zhang, Lingang; Shen, Baifei; Xu, Jiancai; Ji, Liangliang; Zhang, Xiaomei; Wang, Wenpeng; Zhao, Xueyan; Yi, Longqing; Yu, Yahong; Shi, Yin; Xu, Tongjun; Xu, Zhizhan


    CO2 laser-driven electron acceleration in low-density plasma is demonstrated using particle-in-cell simulation. An intense CO2 laser pulse of long wavelength excites a wake bubble that has a large elongated volume for accelerating a large number of electrons before reaching the charge saturation limit. A transversely injected laser pulse is used to induce and control the electron injection. It is found that an electron bunch with total charge up to 10 nC and absolute energy spread less than 16 MeV can be obtained. As a result, the charge per energy interval of the bunch reaches up to 0.6 nC/MeV. Intense CO2-laser based electron acceleration can provide a new direction for generating highly charged electron bunches with low energy spread, which is of much current interest, especially for table-top X-ray generation.

  19. Thermal measurements of short-duration CO2 laser resurfacing (United States)

    Harris, David M.; Fried, Daniel; Reinisch, Lou; Bell, Thomas; Lyver, Rex


    The thermal consequences of a 100 microsecond carbon-dioxide laser used for skin resurfacing were examined with infrared radiometry. Human skin was evaluated in a cosmetic surgery clinic and extirpated rodent skin was measured in a research laboratory. Thermal relaxation following single pulses of in vivo human and ex vivo animal skin were quantitatively similar in the 30 - 1000 msec range. The thermal emission from the area of the irradiated tissue increased monotonically with increasing incident laser fluence. Extremely high peak temperatures during the 100 microsecond pulse are attributed to plume incandescence. Ejecta thermal emission may also contribute to our measurements during the first several msecs. The data are combined into a thermal relaxation model. Given known coefficients, and adjusting tissue absorption to reflect a 50% water content, and thermal conductivity of 2.3 times that of water, the measured (both animal back and human forearm) and calculated values coincide. The high thermal conductance suggests preferential thermal conduction along the protein matrix. The clinical observation of a resurfacing procedure clearly shows thermal overlap and build-up is a result of sequential, adjacent pulses. A decrease of 4 - 6 degrees Celsius in surface temperature at the treatment site that appeared immediately post-Tx and gradually diminished over several days is possibly a sign of dermal convective and/or evaporative cooling.

  20. Energy balance in high-power CO2 laser welding (United States)

    Del Bello, Umberto; Rivela, Cristina; Cantello, Maichi; Penasa, Mauro


    The laser energy impinging on a metal workpiece is partially absorbed and partially reflected by the material surface. This work is aimed at gaining a better insight into the energy balance of the process, and it can also provide the correct input for process modeling and the optimum choice of parameters for increasing welding efficiency. Measurements of the absorption coefficient were made using platinum-platinum rhodium thermocouples which monitored the temperature rise. The radiation backscattered by the workpiece or plasma plume was also recorded, and tests were performed to measure the total amount of material lost by evaporation during laser welding. All the tests were performed on austenitic stainless steel. The resulting absorption curves show different behavior at low or high speed and this can be explained only by taking into account the influence on the process of both the size and inclination of the keyhole. To conserve the keyhole, the interaction process must be rapidly interrupted so as to freeze the molten material and preserve the cavity in the form assumed during the process. A fast mechanical switch has been devised and tests seem to confirm the assumption made.

  1. Laser surgery in otolaryngology: interaction of CO2 laser and soft tissue. (United States)

    Mihashi, S; Jako, G J; Incze, J; Strong, M S; Vaughan, C W


    The sequence of histological change induced by CO2 laser irradiation was discussed in terms of two factors: the physiomechanical factor and the physiochemical factor. At sufficiently high heat energy levels, the immediate findings are characterized by crater formation resulting from rapid vaporization of the water and ejection of the solid component. In the immediate vicinity of the crater edge, the maximum tissue temperature rise is 65 degrees C above the 32 degrees C ambient tissue temperature and it decreases to the primary tissue temperature within a distance of 2 mm. The healing process of CO2 laser induced lesions proceeds with minimal delay. The lymphatic and vascular channels are occluded in the marginal area of coagulation resulting in a marked hemostatic effect. This sealing effect increases the margin of safety in preventing possible dissemination of tumor cells. By selecting the appropriate power, time, and focus cone angle, precise destruction of preselected areas of tissue can be achieved with an extraordinary hemostatic effect without damaging the underlying tissue. These advantages are especially helpful in function-preserving surgery.

  2. High power pulsed fiber laser development for Co2 space based dial system (United States)

    Canat, Guillaume; Le Gouët, Julien; Lombard, Laurent; Bresson, Alexandre; Goular, Didier; Dolfi-Bouteyre, Agnès.; Duzellier, Sophie; Boivin, Denis; Nilsson, Johan; Sahu, Jayata; Bordais, Sylvain


    High energy fiber lasers emitting around 1579nm is seen as a possible technology for the laser unit of a spaceborn CO2 DIAL system. We are developing an all fiber system with the following expected performances: pulse energy of 260μJ, pulse duration 150ns, beam quality M2 laser stability 200 kHz. One of our main concerns has been the radiation induced attenuation mitigation. Various fiber compositions have been investigated.

  3. Laser welding of nylon thin films using a pulsed CO2 waveguide laser (United States)

    Villagomez, R.; Valenzuela, Rogelio; Camacho-Mesa, Roxana B.


    In this work, we present an experimental investigation for welding Nylon: Bi-Oriented Polyamide (BOPA) thin films using a CO2 waveguide laser in a pulsed configuration. The material used in this study is Nylon 6, all set in square sheet thin films samples of 100 cm2 with 15 µm thickness. Our optical setup is based on deliver the laser beam all the way through the work piece using X-Y scanning mirrors mounted on galvo-like motors and an f-theta lens with 15 cm focal length and 50 µm focal spot sizes. The fluence (laser energy) is controlled by a pulse signal generator having the possibility to change the pulse repetition rate (PRR) and the pulse width (PW) of the laser beam. Our results show the best weld seam for scanning speeds of 20mm/s and the pulsed laser beam with 2 KHz PRR and 80 µs for the PW time. The scanning speed and trajectory for the welding process are all controlled by a computer in which one can modify the weld parameters. The irradiance at the focal point is set to 1.146 MW/cm2 while the average optical power was set to 22.5W. Our experimental parameters are previously modeled by using COMSOL Multiphysics software were the laser heat source is modeled on the selected material. This model is based on the heat transfer partial differential equation and solved by finite elements procedure. Model results show a perfect agreement with the experiments. Finally, the quality of the welded seam is studied by means of sealed tight and share force critical mechanical test.

  4. Pulsed TEA CO2 Laser Irradiation of Titanium in Nitrogen and Carbon Dioxide Gases (United States)

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


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

  5. Complications in CO2 Laser Transoral Microsurgery for Larynx Carcinomas

    Directory of Open Access Journals (Sweden)

    Estomba, Carlos Miguel Chiesa


    Full Text Available Introduction Transoral laser microsurgery (TLM has established itself as an effective option in the management of malignant tumors of the glottis, supraglottis, and hypopharynx. Nonetheless, TLM is not a harmless technique. Complications such as bleeding, dyspnea, or ignition of the air may appear in this type of surgery. Objective The aim of this study is to describe the complications that occurred in a group of patients treated for glottic and supraglottic carcinomas in all stages by TLM. Methods This study is a retrospective analysis of patients diagnosed with squamous cell carcinoma of the glottis and supraglottis for all stages (T1, T2, T3, T4, N -/ + , M -/+ treated with TLM between January 2009 and March 2012 in a tertiary hospital. Results Ninety-eight patients met the inclusion criteria, which had undergone a total of 131 interventions. Ninety-four (95.9% patients were male and 4 (4.1% were female. The mean age was 64.2 years (± 10.7 years = min 45; max 88. The presence of intraoperative complications was low, affecting only 2% of patients. Immediate postoperative complications occurred in 6.1%, whereas delayed complications affected 13.2% of patients, without any of them being fatal. Conclusion TLM has shown good oncologic results and low complication rate compared with traditional open surgery during intervention, in the immediate and delayed postoperative period and in the long-term with respect to radiotherapy.

  6. Output power characteristics of cw waveguide CO/sub 2/ laser

    Energy Technology Data Exchange (ETDEWEB)

    Lee, M.H. (Inha Univ., Inchon (Republic of Korea))


    A compact cw CO/sub 2/ waveguide laser was constructed. The characteristics of CO/sub 2/ waveguide laser for the mixing ratio and the pressure difference between inlet and outlet of discharge tube are described. An output power 1W was obtained from a pyrex waveguide tube having a 15cm in length and a 2mm in diameter on the condition that the mixing ratio was 2CO/sub 2/:3N/sub 2/:5He by volume and the pressure difference between inlet and outlet was 50 torr. The volumetric power of laser was 2.3W/cm/sup 3/ for the active volume, which was 10 times larger than conventional CO/sub 2/ laser. Linearly polarized transverse modes LPsub(01) and LPsub(11) were observed by using the thermal paper. Beam divergence and diameter were 9mr and 3.3mm for LPsub(01) mode.

  7. Shallow melting of thin heavily doped silicon layers by pulsed CO2 laser irradiation

    International Nuclear Information System (INIS)

    James, R.B.; Christie, W.H.


    We show that an extremely shallow (approx. 2 laser pulse. Since the absorption of the CO 2 laser pulse is dominated by free-carrier transitions, the beam heating occurs primarily in the thin degenerately doped film at the sample surface, and there is little energy deposited in the underlying lightly doped substrate. For CO 2 pulse-energy densities exceeding a threshold value of about 5 J/cm 2 , surface melting occurs and the reflectivity of the incident laser pulse increases abruptly to about 90%. This large increase in the reflectivity acts like a switch to reflect almost all of the energy in the remainder of the CO 2 laser pulse, thereby greatly reducing the amount of energy available to drive the melt front to deeper depths in the material. This is in contrast to the energy deposition of a laser pulse that has a photon energy exceeding the band gap, in which case the penetration depth of the incident radiation is only weakly affected by the free-carrier density. Transmission electron microscopy shows no extended defects in the near-surface region after CO 2 laser irradiation, and van der Pauw electrical measurements verify that 100% of the implanted arsenic dopant is electrically active. Calculated values for the melt depth versus incident pulse-energy density (E/sub L/) indicate that there exists a window where the maximum melt-front penetration increases slowly with increasing E/sub L/ and has a value of less than a few hundred angstroms

  8. Advanced concepts for high-power, short-pulse CO2 laser development (United States)

    Gordon, Daniel F.; Hasson, Victor; von Bergmann, Hubertus; Chen, Yu-hsin; Schmitt-Sody, A.; Penano, Joseph R.


    Ultra-short pulse lasers are dominated by solid-state technology, which typically operates in the near-infrared. Efforts to extend this technology to longer wavelengths are meeting with some success, but the trend remains that longer wavelengths correlate with greatly reduced power. The carbon dioxide (CO2) laser is capable of delivering high energy, 10 micron wavelength pulses, but the gain structure makes operating in the ultra-short pulse regime difficult. The Naval Research Laboratory and Air Force Research Laboratory are developing a novel CO2 laser designed to deliver ~1 Joule, ~1 picosecond pulses, from a compact gain volume (~2x2x80 cm). The design is based on injection seeding an unstable resonator, in order to achieve high energy extraction efficiency, and to take advantage of power broadening. The unstable resonator is seeded by a solid state front end, pumped by a custom built titanium sapphire laser matched to the CO2 laser bandwidth. In order to access a broader range of mid infrared wavelengths using CO2 lasers, one must consider nonlinear frequency multiplication, which is non-trivial due to the bandwidth of the 10 micron radiation.

  9. Synthesis of higher diamondoids by pulsed laser ablation plasmas in supercritical CO2 (United States)

    Nakahara, Sho; Stauss, Sven; Kato, Toru; Sasaki, Takehiko; Terashima, Kazuo


    Pulsed laser ablation (wavelength 532 nm; fluence 18 J/cm2; pulse width 7 ns; repetition rate 10 Hz) of highly oriented pyrolytic graphite was conducted in adamantane-dissolved supercritical CO2 with and without cyclohexane as a cosolvent. Micro-Raman spectroscopy of the products revealed the presence of hydrocarbons possessing sp3-hybridized carbons similar to diamond structures. The synthesis of diamantane and other possible diamondoids consisting of up to 12 cages was confirmed by gas chromatography-mass spectrometry. Furthermore, gas chromatography-mass spectrometry measurements of samples before and after pyrolysis treatment indicate the synthesis of the most compact decamantane, namely, superadamantane. It is thought that oxidant species originating from CO2 during pulsed laser ablation might lead to the selective dissociation of C-H bonds, enabling the synthesis of low H/C ratio molecules. Therefore, laser ablation in supercritical CO2 is proposed as a practical method for synthesizing diamondoids.

  10. A 490 W transversely excited atmospheric CO2 spark gap laser with added H2 (United States)

    Zand, M.; Koushki, A. M.; Neshati, R.; Kia, B.; Khorasani, K.


    In this paper we present a new design for a high pulse repetition rate transversely excited atmospheric CO2 laser with ultraviolet pre-ionization. A new method of fast thyristor capacitor charging and discharging by a spark gap is used. The effect of H2 gas addition on the output and stability of a transversely excited atmospheric laser operating with a basic mixture of CO2, N2 and He is investigated. The output power was increased by adding H2 to the gas mixture ratio of CO2:N2:He:H2  =  1:1:8:0.5 at total pressure of 850 mbar. An average power of 490 W at 110 Hz with 4.5 J per pulse was obtained. The laser efficiency was 11.2% and oxygen gas was used in the spark gap for electron capture to reduce the recovery time and increase the repetition rate.

  11. Design and performance of a sealed CO2 laser for industrial applications

    International Nuclear Information System (INIS)

    Botero, G; Gomez, D; Nisperuza, D; Bastidas, A


    A large amount of materials processing is done using an industrial CO 2 laser operating in the mid-infrared (IR) spectrum. Their high efficiency and tremendous power output have made them one of the most commonly known transition wavelength at 10,6 microns facilitates laser cutting, drilling and marking of a wide variety of materials in the electronics and medical industries. Because lasers are feedback systems, many of their design parameters strongly interact with one another, and arriving at an optimum design requires a really thorough understanding of just how they interact. We report the construction of a sealed CO2 gas discharge laser with a glass laser tube design as well as clear acrylic housing makes this an excellent demonstrational tool. Sealed operation was characterized in mode, power, warm-up and stability over a long time. The results indicate a good operation, optimum wavelength, powers and beam quality will remove material more efficiently in effective industrial applications.

  12. Multi-criteria optimization in CO2 laser ablation of multimode polymer waveguides (United States)

    Tamrin, K. F.; Zakariyah, S. S.; Sheikh, N. A.


    High interconnection density associated with current electronics products poses certain challenges in designing circuit boards. Methods, including laser-assisted microvia drilling and surface mount technologies for example, are being used to minimize the impacts of the problems. However, the bottleneck is significantly pronounced at bit data rates above 10 Gbit/s where losses, especially those due to crosstalk, become high. One solution is optical interconnections (OI) based on polymer waveguides. Laser ablation of the optical waveguides is viewed as a very compatible technique with ultraviolet laser sources, such as excimer and UV Nd:YAG lasers, being used due to their photochemical nature and minimal thermal effect when they interact with optical materials. In this paper, the authors demonstrate the application of grey relational analysis to determine the optimized processing parameters concerning fabrication of multimode optical polymer waveguides by using infra-red 10.6 μm CO2 laser micromachining to etch acrylate-based photopolymer (Truemode™). CO2 laser micromachining offers a low cost and high speed fabrication route needed for high volume productions as the wavelength of CO2 lasers can couple well with a variety of polymer substrates. Based on the highest grey relational grade, the optimized processing parameters are determined at laser power of 3 W and scanning speed of 100 mm/s.

  13. Nonlinear guiding of picosecond CO2 laser pulses in atmosphere(Conference Presentation) (United States)

    Tochitsky, Sergei


    During the last 20 years much attention has been given to the study of propagation of short intense laser pulses for which the peak power exceeds the critical power of self-focusing, Pcr. For a laser power P laser-ionized plasma result in the production of a high intensity laser filament in air within which a variety of nonlinear optical phenomena are observed. However, research in the 0.8-1 μm range so far has shown a fundamental limitation of guided energy to a few mJ transported within an 100 μm single channel. A long-wavelength, 0 10 μm CO2 laser is a promising candidate for nonlinear guiding because expected high Pcr values according to the modeling should allow for the increase of energy (and therefore power) in a self-guided beam from mJ (GW) to few Joules (TW). During the last decade a significant progress has been achieved in amplification of picosecond pulses to terawatt and recently to lasers open possibility for nonlinear propagation studies in an atmospheric window with high transmission. As a natural first step in a our program on picosecond CO2 laser filamentation, we have made first measurements of Kerr coefficients of air and air constituents around 10 μm. We also undertook direct measurements of n2 of air by analyzing nonlinear self-focusing in air using a 3 ps, 600 GW pulses of the BNL CO2 laser.

  14. LASER BIOLOGY AND MEDICINE: Laser analysis of the 13C/12C isotope ratio in CO2 in exhaled air (United States)

    Stepanov, E. V.


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

  15. Comparison of fiber delivered CO2laser and electrocautery in transoral robot assisted tongue base surgery. (United States)

    Karaman, Murat; Gün, Taylan; Temelkuran, Burak; Aynacı, Engin; Kaya, Cem; Tekin, Ahmet Mahmut


    To compare intra-operative and post-operative effectiveness of fiber delivered CO 2 laser to monopolar electrocautery in robot assisted tongue base surgery. Prospective non-randomized clinical study. Twenty moderate to severe obstructive sleep apnea (OSA) patients, non-compliant with Continuous Positive Airway Pressure (CPAP), underwent Transoral Robotic Surgery (TORS) using the Da Vinci surgical robot in our University Hospital. OSA was treated with monopolar electrocautery in 10 patients, and with flexible CO 2 laser fiber in another 10 patients. The following parameters in the two sets are analyzed: Intraoperative bleeding that required cauterization, robot operating time, need for tracheotomy, postoperative self-limiting bleeding, length of hospitalization, duration until start of oral intake, pre-operative and post-operative minimum arterial oxygen saturation, pre-operative and post-operative Epworth Sleepiness Scale score, postoperative airway complication and postoperative pain. Mean follow-up was 12 months. None of the patients required tracheotomy and there were no intraoperative complications related to the use of the robot or the CO 2 laser. The use of CO 2 laser in TORS-assisted tongue base surgery resulted in less intraoperative bleeding that required cauterization, shorter robot operating time, shorter length of hospitalization, shorter duration until start of oral intake and less postoperative pain, when compared to electrocautery. Postoperative apnea-hypopnea index scores showed better efficacy of CO 2 laser than electrocautery. Comparison of postoperative airway complication rates and Epworth sleepiness scale scores were found to be statistically insignificant between the two groups. The use of CO 2 laser in robot assisted tongue base surgery has various intraoperative and post-operative advantages when compared to monopolar electrocautery.

  16. Endoscopic removal of PMMA in hip revision surgery with a CO2 laser (United States)

    Sazy, John; Kollmer, Charles; Uppal, Gurvinder S.; Lane, Gregory J.; Sherk, Henry H.


    Purpose: to compare CO2 laser to mechanical means of PMMA removal in total hip arthroplasty revision surgery. Materials and methods: Forty-five patients requiring hip revision surgery were studied and compared to historical controls. Cement was removed from the femoral canal utilizing a 30 centimeter laparoscope. A CO2 laser waveguide was passed through the laparoscope into the femoral canal and a TV camera was placed over the eye piece to permit visualization of the depths of the femoral canal on a video monitor. The leg was placed in a horizontal position which avoided the pooling of blood or saline in the depths of the femur. Under direct vision the distal plug could be vaporized with a 40 centimeter CO2 laser waveguide. Power settings of 20 to 25 watts and a superpulsed mode were used. A 2 mm suction tube was welded to the outside of the laparoscope permitting aspiration of the products of vaporization. Results: Of 45 hip revisions there were no shaft perforation, fractures or undue loss of bone stock. There was no statistically different stay in hospital time, blood loss or operative time between the CO2 revision group compared to the non-laser revision group, in which cement was removed by mechanical methods. Conclusions: Mechanical methods used in removing bone cement using high speed burrs, reamers, gouges, and osteotomies is technically difficult and fraught with complications including shaft fracture, perforations, and unnecessary loss of bone stock. The authors' experience using the CO2 laser in hip revision surgery has permitted the removal of bone cement. Use of a modified laparoscope has allowed for precise, complete removal of bone cement deep within the femoral shaft without complication or additional operative time. The authors now advocate the use of a CO2 laser with modified laparoscope in hip revision surgery in which bone cement is to be removed from within the femoral shaft.

  17. Electron transport in solid targets and in the active mixture of a CO2 laser amplifier (United States)

    Galkowski, A.

    The paper examines the use of the NIKE code for the Monte Carlo computation of the deposited energy profile and other characteristics of the absorption process of an electron beam in a solid target and the spatial distribution of primary ionization in the active mixture of a CO2 laser amplifier. The problem is considered in connection with the generation of intense electron beams and the acceleration of thin metal foils, as well as in connection with the electric discharge pumping of a CO2 laser amplifier.

  18. Pseudodysplastic epithelial artefacts associated with oral mucosa CO2 laser excision: an assessment of margin status. (United States)

    Seoane, J; Caballero, T G; Urizar, J M A; Almagro, M; Mosquera, A G; Varela-Centelles, P


    Using a CO(2) laser beam for biopsy is compromised by thermal cytological artefacts that could be critical when assessing dysplastic changes, as they may simulate cytological atypia. This study examined wounds caused by CO(2) laser, evaluating their size and features, utilizing 25 Sprage rats randomly allocated to five groups: four glossectomized using a CO(2) laser at 3, 6, 9 and 12 W and a control group treated with a conventional scalpel. Samples were prepared in 4 microm sections, stained, and studied double-blind by two pathologists. The artefacts identified included cellular and nuclear polymorphism, nuclear hyperchromatism and loss of intercellular adherence; they were mainly located in the basal and suprabasal layers of the oral epithelium. Number of artefacts per specimen did not differ between experimental groups. The width of epithelial damage adjacent to the laser incisions revealed 298.7+/-150.7 microm of damaged tissue (range 100-750 microm), with no differences between low (3 W) and high wattages (6, 9 and 12 W) (X(i)-X(j)=41.6; 95% CI=-125.1 to 208.4). No changes were observed in the control group. CO(2) laser (3-12 W) generates epithelial damage that can simulate light dysplasia with atypias mainly affecting basal and suprabasal layers that may lead to erroneous therapy. Copyright 2010 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  19. [Treatment of giant congenital nevus with high-energy pulsed CO2 laser]. (United States)

    Michel, J L; Caillet-Chomel, L


    All authors agree upon the need for early treatment of giant congenital nevi. The surgeon must seek to minimize the risk of malignancy. The objective calls for radical excision of all pigmented areas; this may be impossible because of the risk of leaving the patient with disfiguring scars. The aim of this study was to assess treatment of giant congenital nevi with the high-energy pulsed CO2 laser as an alternative to surgery. Between 1998 and 1999, the high-energy pulsed CO2 laser was used in nine newborns and five children. The treatment with the high-energy pulsed CO2 laser achieved 70-90% clearing of the giant nevi in most of the children. Two children developed hypertrophic scars on a companion nevi and on giant congenital nevi. One child required a skin graft because of tissue necrosis, associated with a disseminated intravascular coagulation and septic shock. Laser is a surface technique proposed when surgical excision cannot be performed because the surface is too large or the localization is incompatible with surgery. Early treatment, in the first 15 days, is not required for the quality of the cosmetic result. The high-energy pulsed CO2 laser provides satisfactory cosmetic results with short cicatrisation time. It allows the treatment of the companion nevi at the same time. The risk of malignant transformation is greatly but not totally reduced. Regular clinical surveillance should help reduce the risk.

  20. Enhancement of low power CO2 laser cutting process for injection molded polycarbonate (United States)

    Moradi, Mahmoud; Mehrabi, Omid; Azdast, Taher; Benyounis, Khaled Y.


    Laser cutting technology is a non-contact process that typically is used for industrial manufacturing applications. Laser cut quality is strongly influenced by the cutting processing parameters. In this research, CO2 laser cutting specifications have been investigated by using design of experiments (DOE) with considering laser cutting speed, laser power and focal plane position as process input parameters and kerf geometry dimensions (i.e. top and bottom kerf width, ratio of the upper kerf to lower kerf, upper heat affected zone (HAZ)) and surface roughness of the kerf wall as process output responses. A 60 Watts CO2 laser cutting machine is used for cutting the injection molded samples of polycarbonate sheet with the thickness of 3.2 mm. Results reveal that by decreasing the laser focal plane position and laser power, the bottom kerf width will be decreased. Also the bottom kerf width decreases by increasing the cutting speed. As a general result, locating the laser spot point in the depth of the workpiece the laser cutting quality increases. Minimum value of the responses (top kerf, heat affected zone, ratio of the upper kerf to lower kerf, and surface roughness) are considered as optimization criteria. Validating the theoretical results using the experimental tests is carried out in order to analyze the results obtained via software.

  1. Standard guidelines of care: CO 2 laser for removal of benign skin lesions and resurfacing

    Directory of Open Access Journals (Sweden)

    Krupashankar D


    Full Text Available Resurfacing is a treatment to remove acne and chicken pox scars, and changes in the skin due to ageing. Machines : Both ablative and nonablative lasers are available for use. CO 2 laser is the gold standard in ablative lasers. Detailed knowledge of the machines is essential. Indications for CO 2 laser: Therapeutic indications: Actinic and seborrheic keratosis, warts, moles, skin tags, epidermal and dermal nevi, vitiligo blister and punch grafting, rhinophyma, sebaceous hyperplasia, xanthelasma, syringomas, actinic cheilitis angiofibroma, scar treatment, keloid, skin cancer, neurofibroma and diffuse actinic keratoses. CO 2 laser is not recommended for the removal of tattoos. Aesthetic indications: Resurfacing for acne, chicken pox and surgical scars, periorbital and perioral wrinkles, photo ageing changes, facial resurfacing. Physicians′ qualifications: Any qualified dermatologist (DVD or MD may practice CO 2 laser. The dermatologist should possess postgraduate qualification in dermatology and should have had specific hands-on training in lasers either during postgraduation or later at a facility which routinely performs laser procedures under a competent dermatologist/plastic surgeon, who has experience and training in using lasers. For the use of CO 2 lasers for benign growths, a full day workshop is adequate. As parameters may vary in different machines, specific training with the available machine at either the manufacturer′s facility or at another centre using the machine is recommended. Facility: CO 2 lasers can be used in the dermatologist′s minor procedure room for the above indications. However, when used for full-face resurfacing, the hospital operation theatre or day care facility with immediate access to emergency medical care is essential. Smoke evacuator is mandatory. Preoperative counseling and Informed consent Detailed counseling with respect to the treatment, desired effects, possible postoperative complications, should be

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

    Directory of Open Access Journals (Sweden)

    Zahra Bahrololoomi


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

  3. Study on Interactions of Continuous Low Power CO2 Laser with Malaysian Molar Teeth (United States)

    Ahmad, A. L.; Jaafar, M. S.; Ramzun, M. R.; Bermakai, M. Yahaya; Ismail, N. E.; Houssien, Hend A. A.


    Recent studies have shown that CO2 lasers can successfully be used at low-energy densities in dentistry. The CO2 laser is effective for a dental hard tissue since it strongly absorbs light in certain regions of the infrared spectrum because of the carbonate and hydroxyl groups in the structure. In this study, nineteen samples of molars extracted human teeth were irradiated with low power CO2 laser. Laser power of 3W, 6W, 9W, 12W, 15W and 18W, with exposure time of 5 s and 10 s, and distance between laser aperture and sample of 4 cm were used. Laser power above 18W is seen to damage the teeth. The teeth compositions were analyzed using the Fourier Transform Infrared Spectroscopy (FTIR). High laser power caused higher reflectance of the beam because the increased in temperature increasing the rate of chemical reaction, hence, the products after the irradiation. This situation can be explained by the Arrhenius equation [1].

  4. Laser-field-related recombination interference in high-order harmonic generation from CO2 molecules

    International Nuclear Information System (INIS)

    Wei Pengfei; Liu Peng; Zeng Zhinan; Guo Xiaodong; Ge Xiaochun; Li Ruxin; Xu Zhizhan; Chen Jing


    We reinvestigate the modulation inversion of angular distribution of high-order harmonic generation (HHG) from impulsively aligned CO 2 molecules. The angular distribution is found to be sensitive to both the harmonic order and the intensity of the driving laser pulse for HHG. The roles of intramolecular quantum interference and the laser intensity are clarified. A laser-field-related recombination interference model is proposed to explain the modulation inversion of harmonic yield with respect to the molecular alignment. We conclude that the two-center interference in the recombination process can be manipulated by changing the laser intensity.

  5. Diagnostics of ionization in air produced by infrared radiation from A pulse CO2 laser (United States)

    Huston, E. S.

    This thesis begins with a brief account of the historical development of the modern concept of the atom and, building on this foundation, the physical principles responsible for the operation of a LASER are presented. A more detailed description is then given of the pulsed CO2 LASER used in this research, including principles of operation and safety procedures. Next, the research itself is described: an analysis of the ionization in air produced by focusing the LASER's infrared radiation. The data are summarized in graphs which map the region of ionization. Following conclusions on the research performed, specific suggestions are made for future work with the LASER.

  6. Effect of CW-laser irradiation of evaporated layers on silicon

    International Nuclear Information System (INIS)

    Bhattacharya, P.K.; Wagh, A.G.; Kansara, M.J.; Srikantiah, R.V.


    Thin layers of Sb and In (150-200 A) evaporated on high purity Si Crystals were irradiated with a CW-Ar ion laser operated in TEM 00 mode in the visible (multiline) range. The laser beam, focused to a 1/e diameter of 40 μm, was scanned across the sample in air at a constant scanning speed using an electronically controlled X-Y scanner. Powers up to 10 W were used and scanning speeds ranged from 0.5 to 1.5 cm/s. Rutherford backscattering and ion channeling analysis of the samples, on the treated, untreated and virgin regions show that up to a few atomic percent of dopant atoms diffuse into the substrate. Axial impurity dips of about 50% show good substitutionality of Sb. Evaporation loss of 40% of the dopant atoms during the laser treatment is exhibited for Sb. The measurements of depth distribution and substitutional concentrations for these dopants are reported. (orig.)

  7. Laser Sounder for Measuring Atmospheric CO2 Concentrations: Progress Toward Ascends (United States)

    Abshire, J. B.; Kawa, S. R.; Riris, H.; Allan, G. R.; Sun, X.; Stephen, M. A.; Wilson, E.; Burris, J. F.; Mao, J.


    The next generation of space-based, active remote sensing instruments for measurement of tropospheric CO2 promises a capability to quantify global carbon sources and sinks at regional scales. Active (laser) methods will extend CO2 measurement coverage in time, space, and perhaps precision such that the underlying mechanisms for carbon exchange at the surface can be understood with .sufficient detail to confidently project the future of carbon-climate interaction and the influence of remediative policy actions. The recent Decadal Survey for Earth Science by the US National Research Council has recommended such a mission called the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) for launch in 2013-2016. We have been developing a laser technique for measurement of tropospheric CO2 for a number of years. Our immediate goal is to develop and demonstrate the method and instrument technology that will permit measurements of the CO2 column abundance over a horizontal path and from aircraft at the few-ppmv level. Our longer-term goal is to demonstrate the required capabilities of the technique, develop a space mission approach, and design the instrument for an ASCENDS-type mission. Our approach is to use a dual channel laser absorption spectrometer (i.e., differential absorption in altimeter mode), which continuously measures from a near-polar circular orbit. We use several co-aligned tunable fiber laser transmitters allowing simultaneous measurement of the absorption from a CO2 line in the 1570 nm band, O2 extinction in the oxygen A-band (near 765 nm), and aerosol backscatter in the same measurement path. We measure the energy of the laser echoes at nadir reflected from land and water surfaces, day and night. The lasers have spectral widths much narrower than the gas absorption lines and are turned on and off the selected CO2 and O2 lines at kHz rates. The gas extinction and column densities for the CO2 and O2 gases are estimated from the ratio of

  8. Fabrication of versatile cladding light strippers and fiber end-caps with CO2 laser radiation (United States)

    Steinke, M.; Theeg, T.; Wysmolek, M.; Ottenhues, C.; Pulzer, T.; Neumann, J.; Kracht, D.


    We report on novel fabrication schemes of versatile cladding light strippers and end-caps via CO2 laser radiation. We integrated cladding light strippers in SMA-like connectors for reliable and stable fiber-coupling of high-power laser diodes. Moreover, the application of cladding light strippers in typical fiber geometries for high-power fiber lasers was evaluated. In addition, we also developed processes to fuse end-caps to fiber end faces via CO2 laser radiation and inscribe the fibers with cladding light strippers near the end-cap. Corresponding results indicate the great potential of such devices as a monolithic and low-cost alternative to SMA connectors.

  9. Inhibition of caries in vital teeth by CO2 laser treatment (United States)

    Rechmann, Peter; Fried, Daniel; Le, Charles Q.; Nelson, Gerald; Rapozo-Hilo, Marcia; Rechmann, Beate M. T.; Featherstone, John D. B.


    In multiple well-controlled laboratory studies enhancing caries resistance of enamel has been successfully reported using short-pulsed 9.6 µm CO2 laser irradiation. The aim of this study was to prove in a short term clinical pilot trial that the use of the CO2 laser will significantly inhibit the formation of carious lesions around orthodontic brackets in vivo in comparison to a non-irradiated control area. Twelve subjects scheduled for extraction of premolars for orthodontic treatment reasons with an average age of 14.6 years were recruited for the 4-week study. Orthodontic brackets were placed on those premolars with a conventional composite resin (Transbond XT, 3M Unitek, REF 712-035) and a defined area next to the bracket was irradiated with a CO2 laser, Pulse System, Inc (PSI) (Model #LPS-500, Los Alamos, New Mexico), wavelength 9.6 μm, pulse duration 20 μs, pulse repetition rate 20 Hz, beam diameter 1,100 μm, average fluence 4.31 +/- 0.11 J/cm2, 20 laser pulses per spot. Premolars were extracted after four weeks for a quantitative assessment of demineralization by cross sectional microhardness testing. The relative mineral loss ΔZ (vol% x µm) for the laser treated enamel was 402 +/- 85 (SE) while the control area showed a significantly higher mineral loss (mean ΔZ 738 +/- 131; P=0.04, unpaired t-test). The laser treatment produced a 46% demineralization inhibition around the orthodontic brackets in comparison to the non-laser treated areas. This study showed, for the first time that a pulsed 9.6 µm CO2 laser works for the prevention of dental caries in the enamel in vital teeth in human mouths.

  10. The first picosecond terawatt CO2 laser at the Brookhaven Accelerator Test Facility

    International Nuclear Information System (INIS)

    Pogorelsky, I.V.; Ben-Zvi, I.; Babzien, M.


    The first terawatt picosecond CO 2 laser will be brought to operation at the Brookhaven Accelerator Test Facility in 1998. System consists of a single-mode TEA oscillator, picosecond semiconductor optical switch, multi-atmosphere. The authors report on design, simulation, and performance tests of the 10 atm final amplifier that allows for direct multi-joule energy extraction in a picosecond laser pulse

  11. Fabrication of polystyrene microfluidic devices using a pulsed CO2 laser system

    KAUST Repository

    Li, Huawei


    In this article, we described a simple and rapid method for fabrication of droplet microfluidic devices on polystyrene substrate using a CO2 laser system. The effects of the laser power and the cutting speed on the depth, width and aspect ratio of the microchannels fabricated on polystyrene were investigated. The polystyrene microfluidic channels were encapsulated using a hot press bonding technique. The experimental results showed that both discrete droplets and laminar flows could be obtained in the device.

  12. Development of tunable high pressure CO2 laser for lidar measurements of pollutants and wind velocities (United States)

    Levine, J. S.; Guerra, M.; Javan, A.


    The problem of laser energy extraction at a tunable monochromatic frequency from an energetic high pressure CO2 pulsed laser plasma, for application to remote sensing of atmospheric pollutants by Differential Absorption Lidar (DIAL) and of wind velocities by Doppler Lidar, was investigated. The energy extraction principle analyzed is based on transient injection locking (TIL) at a tunable frequency. Several critical experiments for high gain power amplification by TIL are presented.

  13. Collisionless dissociation and isotopic enrichment of SF6 using high-powered CO2 laser radiation (United States)

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


    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.

  14. Spectrally Tailored Pulsed Thulium Fiber Laser System for Broadband Lidar CO2 Sensing (United States)

    Heaps, William S.; Georgieva, Elena M.; McComb, Timothy S.; Cheung, Eric C.; Hassell, Frank R.; Baldauf, Brian K.


    Thulium doped pulsed fiber lasers are capable of meeting the spectral, temporal, efficiency, size and weight demands of defense and civil applications for pulsed lasers in the eye-safe spectral regime due to inherent mechanical stability, compact "all-fiber" master oscillator power amplifier (MOPA) architectures, high beam quality and efficiency. Thulium fiber's longer operating wavelength allows use of larger fiber cores without compromising beam quality, increasing potential single aperture pulse energies. Applications of these lasers include eye-safe laser ranging, frequency conversion to longer or shorter wavelengths for IR countermeasures and sensing applications with otherwise tough to achieve wavelengths and detection of atmospheric species including CO2 and water vapor. Performance of a portable thulium fiber laser system developed for CO2 sensing via a broadband lidar technique with an etalon based sensor will be discussed. The fielded laser operates with approximately 280 J pulse energy in 90-150ns pulses over a tunable 110nm spectral range and has a uniquely tailored broadband spectral output allowing the sensing of multiple CO2 lines simultaneously, simplifying future potentially space based CO2 sensing instruments by reducing the number and complexity of lasers required to carry out high precision sensing missions. Power scaling and future "all fiber" system configurations for a number of ranging, sensing, countermeasures and other yet to be defined applications by use of flexible spectral and temporal performance master oscillators will be discussed. The compact, low mass, robust, efficient and readily power scalable nature of "all-fiber" thulium lasers makes them ideal candidates for use in future space based sensing applications.

  15. Impact of CO2 laser and stannous fluoride on primary tooth erosion. (United States)

    Rocha, Cristiane Tomaz; Turssi, Cecilia Pedroso; Rodrigues-Júnior, Antonio Luiz; Corona, Silmara Aparecida Milori


    This study evaluated in vitro the effect of input power of CO2 laser, either associated or not to stannous fluoride (SnF2) gel, for the control of intrinsic erosion in primary teeth. One hundred four enamel slabs (3 × 3 × 2 mm) from human primary molars were flattened and polished. Adhesive tapes were placed on their surface leaving a window of 3 × 1 mm. Slabs were then cycled four times in 0.01 M hydrochloric acid (pH 2, 2 min) and in artificial saliva (2 h) for creation of erosive lesions. Specimens were randomly assigned into eight groups (n = 13) according to fluoride application [absent (control) or 0.4% stannous fluoride gel (SnF2)] and input power of CO2 laser [unlased (control), 0.5, 1.0 or 1.5 W]. The CO2 laser irradiation was performed in an ultra-pulse mode (100 μs of pulse duration), 4-mm working distance, for 10 s. Specimens were then submitted to further erosive episodes for 5 days and evaluated for enamel relative permeability. Fluoride did not show any protective effect for any of the laser-treated groups or control (p = 0.185). However, a significant effect was detected for input power of CO2 laser (p = 0.037). Tukey's test showed that there was a significant statistically difference between specimens irradiated with 0.5 and 1.5 W (p = 0.028). The input power of 0.5 W showed lower permeability. Variation of input power CO2 laser can influence enamel permeability, at the power of 1.5 W which promoted greater permeability.

  16. Pulsed photothermal radiometry in investigation of tissue destruction caused by CO2 laser action (United States)

    Chebotareva, Galina P.; Zubov, Boris V.; Nikitin, Alexander P.; Rakcheev, Anatolii P.; Alexeeva, Larisa R.


    Pulsed photothermal radiometry (PPTR) of tissue based on the analysis of thermal radiation kinetics measured from tissue at laser heating is an effective method of laser-tissue interaction investigation. The processes of destruction under laser radiation action (coagulation, fusion and welding), which are characterized by definite dynamics of temperature in the region of laser heating, have been studied. The amplitude and kinetics of the thermal signal registered by PPTR technique depend on space and temporal temperature changes in the zone of heating, which is conditioned by the regime of laser action and internal processes in tissue. In the present study the investigation of thermal tissue destruction under action of high-power pulsed CO2 and YAG:Er-laser radiation has been carried out using PPTR. Soft and hard tissues have been examined. The nonlinear dependencies of thermal emission kinetics, the thermal signal amplitude, and the integral absorption on laser energy density are presented and discussed. We represent PPTR as a technique which can be used for the definition of the destruction threshold and for the regulation of laser action on tissue. PPTR method has been applied in clinics with the aim of more accurate definition of CO2 pulsed medical laser radiation dose for treatment of patients with different dermatological diseases.

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


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


    Previous studies have demonstrated that the permeability changes due to the surface modification of dentin can be quantified via thermal imaging during dehydration. The CO2 laser has been shown to remove the smear layer and disinfect root canals. Moreover, thermal modification via CO2 laser irradiation can be used to convert dentin into a highly mineralized enamel-like mineral. The purpose of this study is to evaluate the radicular dentin surface modification after CO2 laser irradiation by me...

  18. Laser Sounder for Global Measurement of CO2 Concentrations in the Troposphere from Space (United States)

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


    Measurements of tropospheric CO2 abundance with global-coverage, a few hundred km spatial and monthly temporal resolution are needed to quantify processes that regulate CO2 storage by the land and oceans. The Orbiting Carbon Observatory (OCO) is the first space mission focused on atmospheric CO2 for measuring total column CO, and O2 by detecting the spectral absorption in reflected sunlight. The OCO mission is an essential step, and will yield important new information about atmospheric CO2 distributions. However there are unavoidable limitations imposed by its measurement approach. These include best accuracy only during daytime at moderate to high sun angles, interference by cloud and aerosol scattering, and limited signal from CO2 variability in the lower tropospheric CO2 column. We have been developing a new laser-based technique for the remote measurement of the tropospheric CO2 concentrations from orbit. Our initial goal is to demonstrate a lidar technique and instrument technology that will permit measurements of the CO2 column abundance in the lower troposphere from aircraft. Our final goal is to develop a space instrument and mission approach for active measurements of the CO2 mixing ratio at the 1-2 ppmv level. Our technique is much less sensitive to cloud and atmospheric scattering conditions and would allow continuous measurements of CO2 mixing ratio in the lower troposphere from orbit over land and ocean surfaces during day and night. Our approach is to use the 1570nm CO2 band and a 3-channel laser absorption spectrometer (i.e. lidar used an altimeter mode), which continuously measures at nadir from a near polar circular orbit. The approach directs the narrow co-aligned laser beams from the instrument's lasers toward nadir, and measures the energy of the laser echoes reflected from land and water surfaces. It uses several tunable fiber laser transmitters which allowing measurement of the extinction from a single selected CO2 absorption line in the 1570

  19. Verruca plana as a complication of CO2 laser treatment: a case report. (United States)

    Winn, Aubrey E; Kentosh, Joshua; Bingham, Jonathan L


    Carbon dioxide (CO2) laser treatment is a common therapeutic modality for many dermatologic conditions. It uses a high energy, infrared beam of light, which selectively targets water-containing tissue resulting in controlled ablative resurfacing. This modality, however, can manifest significant cosmetic side effects. Here we report a case of verruca plana manifesting as a response to CO2 laser treatment. A 74-year-old female with recent Mohs surgery for a basal cell carcinoma, presented for full-face-fractionated CO2 treatment to address her surgical scars in addition to treating her mild diffuse actinic damage. Six weeks post treatment, the patient developed erythematous thin plaques over the areas that had been treated. Histology was consistent with verruca plana. Lesions showed mild improvement with topical tretinoin. Verruca plana are benign and typically self-limited; however, they can present a significant cosmetic burden to patients and are an important complication to consider when performing elective cosmetic procedures.

  20. Development of CO2 and KrF gas lasers as drivers for inertial confinement fusion

    International Nuclear Information System (INIS)

    Rockwood, S.D.


    Several different driver systems are currently under development in the national ICF program. Los Alamos has traditionally emphasized gas laser systems because of their intrinsic high average power capability and ease of operation. This paper will review the status of activities in both carbon dioxide (CO 2 ) and krypton fluoride (KrF) development at the Laboratory

  1. Rapid prototyping of biodegradable microneedle arrays by integrating CO2 laser processing and polymer molding

    International Nuclear Information System (INIS)

    Tu, K T; Chung, C K


    An integrated technology of CO 2 laser processing and polymer molding has been demonstrated for the rapid prototyping of biodegradable poly-lactic-co-glycolic acid (PLGA) microneedle arrays. Rapid and low-cost CO 2 laser processing was used for the fabrication of a high-aspect-ratio microneedle master mold instead of conventional time-consuming and expensive photolithography and etching processes. It is crucial to use flexible polydimethylsiloxane (PDMS) to detach PLGA. However, the direct CO 2 laser-ablated PDMS could generate poor surfaces with bulges, scorches, re-solidification and shrinkage. Here, we have combined the polymethyl methacrylate (PMMA) ablation and two-step PDMS casting process to form a PDMS female microneedle mold to eliminate the problem of direct ablation. A self-assembled monolayer polyethylene glycol was coated to prevent stiction between the two PDMS layers during the peeling-off step in the PDMS-to-PDMS replication. Then the PLGA microneedle array was successfully released by bending the second-cast PDMS mold with flexibility and hydrophobic property. The depth of the polymer microneedles can range from hundreds of micrometers to millimeters. It is linked to the PMMA pattern profile and can be adjusted by CO 2 laser power and scanning speed. The proposed integration process is maskless, simple and low-cost for rapid prototyping with a reusable mold. (paper)

  2. Rapid prototyping of biodegradable microneedle arrays by integrating CO2 laser processing and polymer molding (United States)

    Tu, K. T.; Chung, C. K.


    An integrated technology of CO2 laser processing and polymer molding has been demonstrated for the rapid prototyping of biodegradable poly-lactic-co-glycolic acid (PLGA) microneedle arrays. Rapid and low-cost CO2 laser processing was used for the fabrication of a high-aspect-ratio microneedle master mold instead of conventional time-consuming and expensive photolithography and etching processes. It is crucial to use flexible polydimethylsiloxane (PDMS) to detach PLGA. However, the direct CO2 laser-ablated PDMS could generate poor surfaces with bulges, scorches, re-solidification and shrinkage. Here, we have combined the polymethyl methacrylate (PMMA) ablation and two-step PDMS casting process to form a PDMS female microneedle mold to eliminate the problem of direct ablation. A self-assembled monolayer polyethylene glycol was coated to prevent stiction between the two PDMS layers during the peeling-off step in the PDMS-to-PDMS replication. Then the PLGA microneedle array was successfully released by bending the second-cast PDMS mold with flexibility and hydrophobic property. The depth of the polymer microneedles can range from hundreds of micrometers to millimeters. It is linked to the PMMA pattern profile and can be adjusted by CO2 laser power and scanning speed. The proposed integration process is maskless, simple and low-cost for rapid prototyping with a reusable mold.

  3. Modeling CO2 laser ablation impulse of polymers in vapor and plasma regimes

    International Nuclear Information System (INIS)

    Sinko, John E.; Phipps, Claude R.


    An improved model for CO 2 laser ablation impulse in polyoxymethylene and similar polymers is presented that describes the transition effects from the onset of vaporization to the plasma regime in a continuous fashion. Several predictions are made for ablation behavior.

  4. CO2 laser Thomson scattering diagnostic for fusion product alpha particle measurement (United States)

    Richards, R. K.; Bennett, C. A.; Fletcher, L. K.; Hunter, H. T.; Hutchinson, D. P.


    A description of a CO2 laser Thomson scattering diagnostic for fusion product alpha particles is presented. Scattering calculations based on CIT plasma parameters are presented and compared to previous work based on TFTR parameters. System components are described and a proof-of-principle test in a nonburning plasma is discussed.

  5. A CO2 laser Thomson scattering diagnostic for fusion product alpha particle measurement (United States)

    Richards, R. K.; Bennett, C. A.; Fletcher, L. K.; Hunter, H. T.; Hutchinson, D. P.

    A description of a CO2 laser Thomson scattering diagnostic for fusion alpha particles is presented. Scattering calculations based on CIT plasma parameters are presented and compared to previous work based on TFTR parameters. Systems components are described and a proof-of-principle test in a nonburning plasma is discussed.

  6. Post-operative morbidity and 1-year outcomes in CO2-laser tonsillotomy versus dissection tonsillectomy

    NARCIS (Netherlands)

    Lourijsen, Evelijn S.; Wong Chung, Justin E. R. E.; Koopman, Jan Pieter; Blom, Henk M.


    Objective: In this study a type of partial tonsil surgery, CO2-laser tonsillotomy, was compared to regular tonsillectomy. The effectiveness and post-operative recovery rate of both interventions in adult patients was assessed by using a questionnaire.Study design: Prospective follow-up

  7. Fine-scale structures in plasmas stimulated by a CO2 laser

    International Nuclear Information System (INIS)

    Grek, B.; Martin, F.; Johnston, T.W.; Pepin, H.; Mitchel, G.; Rheault, F.


    Remarkable density structures are observed in the plasma generated during the rise of a high-power CO 2 laser. Jetlike structures and density bowls are seen in interferograms. Infrared imaging shows that these bowls are linked to localized Brillouin-instability backscatter. Depolarization measurements also exhibit filamentary structures that extend far into the underdense regions of the plasma

  8. Efficacy of fractional CO2 laser in treatment of atrophic scar of cutaneous leishmaniasis. (United States)

    Banihashemi, Mahnaz; Nahidi, Yalda; Maleki, Masoud; Esmaily, Habibollah; Moghimi, Hamid Reza


    Cutaneous leishmaniasis is an endemic disease in Iran. Unfortunately, it can lead to unsightly atrophic scars with limited treatment options. Fractional CO2 laser is accepted for treatment of atrophic acne scars and recently has been used to treat cutaneous leishmaniasis, so we planned to use fractional CO2 laser on leishmaniasis scar. We conducted this study on 60 leishmaniasis scars on the face of 40 patients. The lesions were treated by a fractional CO2 laser with beam size of 120 μm, with energy of 50-90 mJ, and 50-100 spots/cm(2) density with two passes in three monthly sessions. Evaluation was done in the first and second months after the first treatment and 3 and 6 months after the last treatment. Digital photography was performed at each visit. Assessment of improvement rate by patient and physician was rated separately as follows: no improvement (0%), mild (high efficacy of fractional CO2 laser for leishmaniasis scar. No significant adverse effects were noted.

  9. Flash evaporation of compounds with a pulsed-discharge CO(2) laser. (United States)

    Calí, C; Daneu, V; Orioli, A; Riva-Sanseverino, S


    Pulsed laser radiation at 10.6 microm has been used to evaporate a number of compounds chosen for their difficulty of evaporation with conventional techniques. An average laser power of 8 W, pulsed at 50 Hz with a 1-msec duration, has been found sufficient to obtain useful evaporation rates for Al(2)O(3) and other highly refractory materials. For easily decomposed materials such as CdS and ZnS, comparison of cw and pulsed evaporation through measurement of optical and photoconductive film properties consistently indicates higher stoichiometry in pulsed evaporation, as well as higher refractive index. The dynamics of film growth during a single laser pulse has been studied by means of a unique thickness monitor.

  10. CO2 laser nerve welding: optimal laser parameters and the use of solders in vitro. (United States)

    Menovsky, T; Beek, J F; van Gemert, M J


    To improve the welding strength, an in vitro study was performed to investigate the bonding strength of CO2 laser nerve welding (LNW), with and without the use of human albumin solution, dried albumin solution, egg white, fibrinogen solution, fibrin glue, and red blood cells as a solder. Fifteen different combinations of laser power (50, 100, and 150 mW) and pulse duration (0.1 to 3 s) were used with a spot size of 320 microns. The results have been compared to suture, fibrin glue, and laser-assisted nerve repair (LANR). The strongest welds (associated with whitening and caramelization of tissue) were produced at 100 mW with pulses of 1.0 s and at 50 mW with pulses of 3 s. The use of a dried albumin solution as a solder at 100 mW with pulses of 1 s increased the bonding strength 9-fold as compared to LNW (bonding strength 21.0 +/- 8.6 g and 2.4 +/- 0.9 g, respectively). However, positioning the nerves between cottons soaked in saline for 20 minutes resulted in a decrease of the bonding strength (9.8 +/- 4.5 g). The use of a 20% albumin solution and egg white, both at 50 mW with pulses of 3 s, resulted in a bonding strength of, respectively, 5.7 +/- 2.1 g and 7.7 +/- 2.4 g. Other solders did not increase the bonding strength in comparison to LNW. The substantial increase in bonding strength for some solders suggests that it is worthwhile to investigate the dehiscence rate and nerve regeneration of solder enhanced LNW in an in vivo study.

  11. Laser Amplifier Development for the Remote Sensing of CO2 from Space (United States)

    Yu, Anthony W.; Abshire, James B.; Storm, Mark; Betin, Alexander


    Accurate global measurements of tropospheric CO2 mixing ratios are needed to study CO2 emissions and CO2 exchange with the land and oceans. NASA Goddard Space Flight Center (GSFC) is developing a pulsed lidar approach for an integrated path differential absorption (IPDA) lidar to allow global measurements of atmospheric CO2 column densities from space. Our group has developed, and successfully flown, an airborne pulsed lidar instrument that uses two tunable pulsed laser transmitters allowing simultaneous measurement of a single CO2 absorption line in the 1570 nm band, absorption of an O2 line pair in the oxygen A-band (765 nm), range, and atmospheric backscatter profiles in the same path. Both lasers are pulsed at 10 kHz, and the two absorption line regions are sampled at typically a 300 Hz rate. A space-based version of this lidar must have a much larger lidar power-area product due to the approximately x40 longer range and faster along track velocity compared to airborne instrument. Initial link budget analysis indicated that for a 400 km orbit, a 1.5 m diameter telescope and a 10 second integration time, a approximately 2 mJ laser energy is required to attain the precision needed for each measurement. To meet this energy requirement, we have pursued parallel power scaling efforts to enable space-based lidar measurement of CO2 concentrations. These included a multiple aperture approach consists of multi-element large mode area fiber amplifiers and a single-aperture approach consists of a multi-pass Er:Yb:Phosphate glass based planar waveguide amplifier (PWA). In this paper we will present our laser amplifier design approaches and preliminary results.

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

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


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

  13. Effects of CO2 Lasers on Dental Pulp Biology in Rats. (United States)

    Ser-Od, Tungalag; Yasumoto, Masafumi; Al-Wahabi, Akram; Nakajima, Kei; Murakami, Satoshi; Matsuzaka, Kenichi; Inoue, Takashi


    The purpose of this study was to investigate the effects of CO2 lasers on the proliferation and differentiation of dental pulp cells, and their latent self-recovery in connection with their stemness using reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemistry. The first molars from male Sprague-Dawley rats, each weighing ∼150-200 g, were used for this study. The upper first molars were irradiated with a 10,600 nm wavelength CO2 laser under identical parameters (2 W CO2 laser, energy 4J, energy density 203.84 J/cm(2) for 8.8 sec) through the dentin of the occlusal surface. The molars were extracted immediately, or at 1, 3 or 5 days after the laser irradiation. RT-PCR analysis using primers specific for heat shock protein 70 (Hsp70), adenosine triphosphate (ATP)-binding cassette transporter G2 (ABCG2), dentin sialophosphoprotein (DSPP), and dentin matrix protein 1 (DMP1), and immunohistochemistry using antibodies specific for proliferating cell nuclear antigen (PCNA), ABCG2, CD34, and CD44 were performed. RT-PCR analysis revealed that Hsp70 mRNA expression in the immediate group and ABCG2 mRNA expression at day 1 were the highest. DSPP and DMP1 mRNA expression in the laser-irradiated groups increased gradually, reaching its peak on the 5th day of the experiment, although no significant difference found among groups with regard to DMP1 expression. Immunohistochemically, PCNA-positive cells were observed at all times after the laser irradiation; however, they were most evident on day 3. CD44-positive cells were observed strongly on day 1 and day 3, while ABCG2-positive cells were the most evident on day 3. These results demonstrate that CO2 laser irradiation induces degeneration in the pulp tissue, which is then repaired by newly formed odontoblast-like cells.

  14. High Repetition Rate Pulsed 2-Micron Laser Transmitter for Coherent CO2 DIAL Measurement (United States)

    Singh, Uprendra N.; Bai, Yingxin; Yu, Jirong; Petros, Mulugeta; Petzar, Paul J.; Trieu, Bo C.; Lee, Hyung


    A high repetition rate, highly efficient, Q-switched 2-micron laser system as the transmitter of a coherent differential absorption lidar for CO2 measurement has been developed at NASA Langley Research Center. Such a laser transmitter is a master-slave laser system. The master laser operates in a single frequency, either on-line or off-line of a selected CO2 absorption line. The slave laser is a Q-switched ring-cavity Ho:YLF laser which is pumped by a Tm:fiber laser. The repetition rate can be adjusted from a few hundred Hz to 10 kHz. The injection seeding success rate is from 99.4% to 99.95%. For 1 kHz operation, the output pulse energy is 5.5mJ with the pulse length of approximately 50 ns. The optical-to-optical efficiency is 39% when the pump power is 14.5W. The measured standard deviation of the laser frequency jitter is about 3 MHz.

  15. Cosmetic and aesthetic skin photosurgery using a computer-assisted CO2 laser-scanning system (United States)

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


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

  16. Efficacy and safety evaluation of an innovative CO2 laser/radiofrequency device in dermatology. (United States)

    Campolmi, P; Bonan, P; Cannarozzo, G; Bruscino, N; Moretti, S


    CO2 laser has not only become the most widely used laser in dermatological surgical practice, but it has also proved to be highly effective in treating aesthetic imperfections. To examine the efficacy and safety of a novel fractional CO2 laser combined with a radiofrequency device in different dermatological, surgical and aesthetic fields. A total of 79 patients were treated in our Outpatient Service with a novel fractional CO2 laser combined with a bipolar radiofrequency device for a maximum of 5 months. Group A consisted of 39 patients with lesions requiring complete excision, whereas Group B consisted of 40 subjects seeking to enhance aesthetic facial imperfections. The results were assessed by three 'blind' investigators using photographs and clinical observations; in addition, the patients had to give their own subjective assessment of the results. At the 6-month follow-up, the lesions of the Group A patients had been completely removed, except for one case of a large sebaceous nevus on the scalp. All the Group B patients showed global improvement in skin tightening, removal of fine lines and rhytides and correction of dilated pores and hyperpigmentation, with no significant side-effects and short downtimes. This kind of laser meets the needs of the majority of dermatologists requiring a unique, versatile tool to remove cutaneous lesions and at the same time, safely and effectively treat skin imperfections. © 2012 The Authors. Journal of the European Academy of Dermatology and Venereology © 2012 European Academy of Dermatology and Venereology.

  17. Comparison of Videonystagmography and Audiological Findings after Stapedotomy; CO2 Laser vs Perforator. (United States)

    Karaca, Sait; Basut, Oğuz; Demir, Uygar Levent; Özmen, Ömer Afşın; Kasapoğlu, Fikret; Coşkun, Hakan


    Various types of laser, microdrill, and perforator are effectively used in the surgical treatment of otosclerosis. However, they have certain disadvantages along with advantages. The aim of this study was to evaluate the effects of carbon dioxide (CO2) laser and perforator stapedotomy techniques on audiological outcomes and postoperative vestibular functions via videonystagmography (VNG). This prospective and randomized clinical study was conducted in an academic tertiary medical center. Sixty-nine patients diagnosed with otosclerosis who underwent stapedotomy were enrolled in this study. Patients were divided into two groups based on the technique used in stapedotomy: CO2 laser and perforator. Postoperative hearing gain and VNG findings were the main outcome measures. Subsequently, the two study groups were compared for analysis. The preoperative air-bone gap was 32.7±8.9 decibel (dB) in the study population and it was improved to 12.9±8.4 dB after operation. There were no differences in VNG findings and vertigo symptoms between the laser and perforator groups at postoperative day 2. There was no significant gain difference regarding the air conduction, bone conduction, and air-bone gap between the two groups (p=0.294, p=0.57, and p=0.37, respectively). Both CO2 laser and perforator stapedotomy have successful audiological outcomes with no difference in postoperative vestibular disturbance.

  18. Controlling the temperature of bones using pulsed CO2 lasers: observations and mathematical modeling. (United States)

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


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

  19. Laser Coulomb Explosion Imaging of molecular dynamics in CO2 molecule (United States)

    Legare, Francois; Bocharova, Irina; Litvinyuk, Igor; Sanderson, Joseph; Karimi, Reza


    Molecular structure dynamics and dissociation pathways of CO2 molecule initiated by interaction with strong laser field were investigated by Laser Coulomb Explosion Imaging (LCEI) technique. Momentum imaging of ions in tree-body fragmentation break-up channels O^++C^++O^+ (1,1,1) and O^2++C^2++O^2+ (2,2,2) was used to determine full geometry of CO2 ionic states before explosion. Varying laser pulse length from sub-7 fs to 200 fs at the same laser field intensity we were able to follow the evolution of the molecular structure and observe dramatic change in total kinetic energy of O^2++C^2++O^2+ channel with increasing pulse length. We observed significantly bent structure of parent ion and low kinetic energy of the (2,2,2) channel for long pulses, compared to the very close to linear geometry, and very high kinetic energy for sub-7 fs laser pulse. This observation supports the idea that a phenomenon known as enhanced ionization takes place for CO2 molecule with the same mechanism as in hydrogen molecule. It also lets us put temporal and spatial limits on this process, and in the future, probing molecular structure within the critical distance range, establish connection between changing geometry and dissociation pathways.

  20. A compact plasma pre-ionized TEA-CO2 laser pulse clipper for material processing (United States)

    Gasmi, Taieb


    An extra-laser cavity CO2-TEA laser pulse clipper using gas breakdown techniques for high spatial resolution material processing and shallow material engraving and drilling processes is presented. Complete extinction of the nitrogen tail, that extends the pulse width, is obtained at pressures from 375 up to 1500 torr for nitrogen and argon gases. Excellent energy stability and pulse repeatability were further enhanced using high voltage assisted preionized plasma gas technique. Experimental data illustrates the direct correlation between laser pulse width and depth of engraving in aluminum and alumina materials.

  1. Energy modulation of nonrelativistic electrons with a CO2 laser using a metal microslit


    Jongsuck, Bae; Ryo, Ishikawa; Sumio, Okuyama; Takashi, Miyajima; Taiji, Akizuki; Tatsuya, Okamoto; Koji, Mizuno


    A metal microslit has been used as an interaction circuit between a CO2 laser beam and nonrelativistic free electrons. Evanescent waves which are induced on the slit by illumination of the laser light modulate the energy of electrons passing close to the surface of the slit. The electron-energy change of more than ±5 eV for the 80 keV electron beam has been observed using the 7 kW laser beam at the wavelength of 10.6 μm.

  2. Energy modulation of nonrelativistic electrons with a CO2 laser using a metal microslit (United States)

    Bae, Jongsuck; Ishikawa, Ryo; Okuyama, Sumio; Miyajima, Takashi; Akizuki, Taiji; Okamoto, Tatsuya; Mizuno, Koji


    A metal microslit has been used as an interaction circuit between a CO2 laser beam and nonrelativistic free electrons. Evanescent waves which are induced on the slit by illumination of the laser light modulate the energy of electrons passing close to the surface of the slit. The electron-energy change of more than ±5 eV for the 80 keV electron beam has been observed using the 7 kW laser beam at the wavelength of 10.6 μm.

  3. Effect of a target on the stimulated emission of microsecond CO2-laser pulses (United States)

    Baranov, V. Iu.; Dolgov, V. A.; Maliuta, D. D.; Mezhevov, V. S.; Semak, V. V.


    The paper reports a change in the pulse shape of a TEA CO2 laser with an unstable cavity under the interaction between the laser radiation and a metal surface in the presence of a breakdown plasma. It is shown that a continuous change in the phase difference between the wave reflected in the cavity and the principal cavity wave gives rise to changes in the pulse shape and the appearance of power fluctuations. The possible effect of these phenomena on the laser treatment of materials is considered.

  4. Investigation of damage to metals by pulsed CO2 laser radiation (United States)

    Vedenov, A. A.; Gladush, G. G.; Drobyazko, S. V.; Senatorov, Yu M.


    A study was made of the physical mechanism involved in piercing holes in metallic plates, using CO2 laser radiation. It was established experimentally that the energy consumed in removing a unit volume of a metal has a minimum, depending on the duration and energy of the laser pulse. An explanation is proposed for the laws governing this behavior, based on ideas of the ejection of liquid from a crater by the vapor pressure of the material. The effect on the interaction efficiency of the absorption of laser radiation in the plasma jet is taken into account.

  5. Application of Factorial Design for Gas Parameter Optimization in CO2 Laser Welding

    DEFF Research Database (Denmark)

    Gong, Hui; Dragsted, Birgitte; Olsen, Flemming Ove


    The effect of different gas process parameters involved in CO2 laser welding has been studied by applying two-set of three-level complete factorial designs. In this work 5 gas parameters, gas type, gas flow rate, gas blowing angle, gas nozzle diameter, gas blowing point-offset, are optimized...... to be a very useful tool for parameter optimi-zation in laser welding process. Keywords: CO2 laser welding, gas parameters, factorial design, Analysis of Variance........ The bead-on-plate welding specimens are evaluated by a number of quality char-acteristics, such as the penetration depth and the seam width. The significance of the gas pa-rameters and their interactions are based on the data found by the Analysis of Variance-ANOVA. This statistic methodology is proven...

  6. Miniaturized Laser Heterodyne Radiometer for Measurements of CO2 in the Atmospheric Column (United States)

    Wilson, E. L.; Mclinden, M. L.; Miller, J. H.; Allan, G. R.; Lott, L. E.; Melroy, H. R.; Clarke, G. B.


    We have developed a low-cost, miniaturized laser heterodyne radiometer for highly sensitive measurements of carbon dioxide (CO2) in the atmospheric column. In this passive design, sunlight that has undergone absorption by CO2 in the atmosphere is collected and mixed with continuous wave laser light that is step-scanned across the absorption feature centered at 1,573.6 nm. The resulting radio frequency beat signal is collected as a function of laser wavelength, from which the total column mole fraction can be de-convolved. We are expanding this technique to include methane (CH4) and carbon monoxide (CO), and with minor modifications, this technique can be expanded to include species such as water vapor (H2O) and nitrous oxide (N2O).

  7. Management of recalcitrant oral pemphigus vulgaris with CO 2 laser - Report of two cases

    Directory of Open Access Journals (Sweden)

    Bhardwaj Ashu


    Full Text Available Laser has been used efficiently for treatment of oral lichen planus, leukoplakia, aphthous ulcers and oral manifestations of HIV. Two cases of recalcitrant oral pemphigus vulgaris that were successfully treated with CO 2 laser are described. The patients had been treated by a dermatologist with pulse therapy of methyl prednisolone and cyclophosphamide over a period of 6 to 8 months, but the clinical course was characterized by episodes of painful flare-ups and nonresponsiveness. The patients were extremely uncomfortable with recurrent oral lesions. CO 2 laser at low power was used to irradiate the lesions. It was shown to be effective in relieving pain and healing of lesions, with nonrecurrence. To the best of our knowledge, this is the first case report of such a treatment of oral pemphigus vulgaris. Further clinical studies are warranted to confirm efficacy and to optimize the treatment protocol.

  8. Biocompatibility enhancement of an inert ceramic using CO2 laser radiation (United States)

    Hao, Liang; Lawrence, Jonathan


    Due to their attractive mechanical properties, bioinert ceramics are frequently used in the high load-bearing sites such as orthopaedic and dental implants, but they are chemically inert and do not naturally form a direct bond with bone and thus are lack of osseointegration. A CO2 laser was used to modify the surface properties of bioinert zirconia with the aim to achieve osseointegration between the material and bone. Higher wettability characteristics generated by the CO2 laser treatment was primarily due to the enhancement of the surface energy, particularly the polar component, determined by way of microstructural changes. An in vitro test using human fetal osteoblast cells (hFOB) revealed that osteoblast cells adhere better on the laser treated sample than the untreated sample. The change in the wettability characteristics could be the main mechanism governing the osteoblast cell adhesion on the YPSZ.

  9. Advantages of CO2 laser use in surgical management of otosclerosis

    Directory of Open Access Journals (Sweden)

    Matković Svjetlana


    Full Text Available Background. Otosclerosis is a progressive osteo-destructive disorder of the bony labyrinth in which the fixation of the stapes causes the hearing loss. The aim of this study was the postoperative determination of parameters of the effect of surgical intervention on hearing and the incidence of complications and, on the basis of the differences in the examined parameters of the study, the estimation of the eficacy of the two mentioned surgical thechniques in the treatment of otosclerosis. Methods. In our research 40 patients with conductive hearing loss caused by otosclerosis underwent surgery with CO2 laser. Functional results were compared postoperatively with the results of 40 patients operated by the classical technique without the use of CO2 laser. The research was accomplished as a prospective comparative study. Results. The air-bone interval (gap as the difference between the rim of air and bone conductivity for separate frequencies did not significantly differ between the control and the experimental group. Both methods were effective in closing the air-bone gap with the rates of closure to within 10 dB in 82.6% and 75.3% for the laser and drill, respectively. The incidence of tinnitus was significantly lower in patients who underwent surgery with CO2 laser. The frequency of intraoperative and postoperative complications was significantly lower in the laser group. Differences were statistically significant for all parameters (p<0.05. Conclusion. On the basis of the degree of postoperative hearing improvement, tinnitus and the incidence of complications it can be concluded that the use of CO2 laser during inverse stapedoplasty represents an effective and safe method, justifying the promotion of its use in the surgical management of otosclerosis.

  10. Development of Laser, Detector, and Receiver Systems for an Atmospheric CO2 Lidar Profiling System (United States)

    Ismail, Syed; Koch, Grady; Abedin, Nurul; Refaat, Tamer; Rubio, Manuel; Singh, Upendra


    A ground-based Differential Absorption Lidar (DIAL) is being developed with the capability to measure range-resolved and column amounts of atmospheric CO2. This system is also capable of providing high-resolution aerosol profiles and cloud distributions. It is being developed as part of the NASA Earth Science Technology Office s Instrument Incubator Program. This three year program involves the design, development, evaluation, and fielding of a ground-based CO2 profiling system. At the end of a three-year development this instrument is expected to be capable of making measurements in the lower troposphere and boundary layer where the sources and sinks of CO2 are located. It will be a valuable tool in the validation of NASA Orbiting Carbon Observatory (OCO) measurements of column CO2 and suitable for deployment in the North American Carbon Program (NACP) regional intensive field campaigns. The system can also be used as a test-bed for the evaluation of lidar technologies for space-application. This DIAL system leverages 2-micron laser technology developed under a number of NASA programs to develop new solid-state laser technology that provides high pulse energy, tunable, wavelength-stabilized, and double-pulsed lasers that are operable over pre-selected temperature insensitive strong CO2 absorption lines suitable for profiling of lower tropospheric CO2. It also incorporates new high quantum efficiency, high gain, and relatively low noise phototransistors, and a new receiver/signal processor system to achieve high precision DIAL measurements.

  11. Quantitative measurement of carbon isotopic composition in CO2 gas reservoir by Micro-Laser Raman spectroscopy (United States)

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


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

  12. Experimental Investigation of Axial and Beam-Riding Propulsive Physics with TEA CO2 laser (United States)

    Kenoyer, D. A.; Salvador, I.; Myrabo, L. N.; Notaro, S. N.; Bragulla, P. W.


    A twin Lumonics K922M pulsed TEA CO2 laser system (pulse duration of approximately 100 ns FWHM spike, with optional 1 μs tail, depending upon laser gas mix) was employed to experimentally measure both axial thrust and beam-riding behavior of Type ♯200 lightcraft engines, using a ballistic pendulum and Angular Impulse Measurement Device (AIMD, respectively. Beam-riding forces and moments were examined along with engine thrust-vectoring behavior, as a function of: a) laser beam lateral offset from the vehicle axis of symmetry; b) laser pulse energy (˜12 to 40 joules); c) pulse duration (100 ns, and 1 μs); and d) engine size (97.7 mm to 161.2 mm). Maximum lateral momentum coupling coefficients (CM) of 75 N-s/MJ were achieved with the K922M laser whereas previous PLVTS laser (420 J, 18 μs duration) results reached only 15 N-s/MJ—an improvement of 5x. Maximum axial CM performance with the K922M reached 225 N-s/MJ, or about ˜3x larger than the lateral CM values. These axial CM results are sharply higher than the 120 N/MW previously reported for long pulse (e.g., 10-18 μs) CO2 electric discharge lasers.

  13. Direct acceleration of electrons by a CO2 laser in a curved plasma waveguide (United States)

    Yi, Longqing; Pukhov, Alexander; Shen, Baifei


    Laser plasma interaction with micro-engineered targets at relativistic intensities has been greatly promoted by recent progress in the high contrast lasers and the manufacture of advanced micro- and nano-structures. This opens new possibilities for the physics of laser-matter interaction. Here we propose a novel approach that leverages the advantages of high-pressure CO2 laser, laser-waveguide interaction, as well as micro-engineered plasma structure to accelerate electrons to peak energy greater than 1 GeV with narrow slice energy spread (~1%) and high overall efficiency. The acceleration gradient is 26 GV/m for a 1.3 TW CO2 laser system. The micro-bunching of a long electron beam leads to the generation of a chain of ultrashort electron bunches with the duration roughly equal to half-laser-cycle. These results open a way for developing a compact and economic electron source for diverse applications.

  14. CO2 laser ablation of bent optical fibers for sensing applications

    International Nuclear Information System (INIS)

    Lévesque, L; Jdanov, V


    A procedure for the fabrication of a fiber optic sensor involving CO 2 laser ablation at λ = 10.6 µm is proposed. A basic system to achieve optical fiber bending and material processing on a single mode optical fiber is described and it is demonstrated that an optical fiber can be bent at a very precise angle by focusing a CO 2 beam locally near the glass cladding surface until it reaches melting temperature. A method is also described for removing material at the apex of a bent fiber to obtain a smooth and well flattened plane surface that is suitable for optical fiber sensing

  15. Simple, compact, and low cost CO2 laser driven by fast high voltage solid state switch for industrial application (United States)

    Tanaka, Miyu; Tei, Masaya; Uno, Kazuyuki; Nakano, Hitoshi


    A longitudinally excited CO2 laser driven with a reverse recovery characteristics of high voltage diode has been developed. A diode is used to control the high voltage pulse as an opening switch. Power supply for longitudinally excited CO2 laser is composed of a pulse generator, transformer, capacitor, and a diode, is very simple. Laser oscillation has been successfully achieved, several tens of mJ in laser energy has been obtained.

  16. Picosecond streak camera diagnostics of CO2 laser-produced plasmas

    International Nuclear Information System (INIS)

    Jaanimagi, P.A.; Marjoribanks, R.S.; Sancton, R.W.; Enright, G.D.; Richardson, M.C.


    The interaction of intense laser radiation with solid targets is currently of considerable interest in laser fusion studies. Its understanding requires temporal knowledge of both laser and plasma parameters on a picosecond time scale. In this paper we describe the progress we have recently made in analysing, with picosecond time resolution, various features of intense nanosecond CO 2 laser pulse interaction experiments. An infrared upconversion scheme, having linear response and <20 ps temporal resolution, has been utilized to characterise the 10 μm laser pulse. Various features of the interaction have been studied with the aid of picosecond IR and x-ray streak cameras. These include the temporal and spatial characteristics of high harmonic emission from the plasma, and the temporal development of the x-ray continuum spectrum. (author)

  17. Flow with vibrational energy exchange, application to CO2 electric laser

    International Nuclear Information System (INIS)

    Dahan, Claude.


    The performances of a continuous wave (CO 2 , N 2 , He) laser ionized by an electron beam are calculated. Several types of phenomena are considered: energy exchange processes between molecules of laser medium, electron molecular excitation processes, aerodynamic phenomena: the energy exchanges accompanying the laser effect generate important quantities of heat, which have to be evacuated by the flow. After a survey of the fundamental assumptions on molecular phenomena, a computer code was developed for following, along the flow, the evolution of the thermodynamic parameters (pressure, temperature), of the laser gain, and of the electrical properties (electron density and temperature). To provide a finer description of the last ones, a model giving the energy distribution of the electrons in the laser medium was established [fr

  18. Energy balance in high-quality cutting of steel by fiber and CO2 lasers (United States)

    Fomin, V. M.; Golyshev, A. A.; Orishich, A. M.; Shulyat'ev, V. B.


    The energy balance of laser cutting of low-carbon and stainless steel sheets with the minimum roughness of the cut surface is experimentally studied. Experimental data obtained in wide ranges of cutting parameters are generalized with the use of dimensionless parameters (Peclet number and absorbed laser energy). It is discovered for the first time that the minimum roughness is ensured at a certain value of energy per unit volume of the melt (approximately 26 J/mm3), regardless of the gas type (oxygen or nitrogen) and laser type (fiber laser with a wavelength of 1.07 μm or CO2 laser with a wavelength of 10.6 μm).

  19. Influence of secondary treatment with CO2 laser irradiation for mitigation site on fused silica surface (United States)

    Jiang, Yong; Zhou, Qiang; Qiu, Rong; Gao, Xiang; Wang, Hui-Li; Yao, Cai-Zhen; Wang, Jun-Bo; Zhao, Xin; Liu, Chun-Ming; Xiang, Xia; Zu, Xiao-Tao; Yuan, Xiao-Dong; Miao, Xin-Xiang


    The ablation debris and raised rim, as well as residual stress and deep crater will be formed during the mitigation of damage site with a CO2 laser irradiation on fused silica surface, which greatly affects the laser damage resistance of optics. In this study, the experimental study combined with numerical simulation is utilized to investigate the effect of the secondary treatment on a mitigated site by CO2 laser irradiation. The results indicate that the ablation debris and the raised rim can be completely eliminated and the depth of crater can be reduced. Notable results show that the residual stress of the mitigation site after treatment will reduce two-thirds of the original stress. Finally, the elimination and the controlling mechanism of secondary treatment on the debris and raised rim, as well as the reasons for changing the profile and stress are analyzed. The results can provide a reference for the optimization treatment of mitigation sites by CO2 laser secondary treatment. Project supported by the National Natural Science Foundation of China (Grant Nos. 61505170, 61505171, and 51535003), the Joint Fund of the National Natural Science Foundation of China, the Chinese Academy of Engineering Physics (Grant No. U1530109), and the China Postdoctoral Science Foundation (Grant No. 2016M592709).

  20. Benefits of CO2 laser heating for high reliability fiber splicing (United States)

    Duke, Douglas M.; Nasir, Usman; Saravanos, Elli


    The use of a CO2 laser as a heat source became commercially available for optical fiber splicing and component fabrication only in recent years. In addition to long-term trouble-free and low-maintenance heat source operation, laser fusion splicing offers unique benefits for fabricating high-power optical components, as well as for splice reliability. When used as the heating method for fiber splicing, the energy of the CO2 laser beam is efficiently absorbed by the outer layer of the glass, and is then conducted inwards. This heating method is well controlled, and results in a smooth and contamination-free glass surface. Other heating methods, such as arc fusion or resistive heating, may leave tungsten, graphite, or metal oxide deposits on the spliced fiber surface. By contrast, with CO2 laser splicing, the lack of surface irregularities and contamination enables remarkable spliced-fiber strength results, with some strength results nearly within the range of coated fiber breaking strength.

  1. Hybrid CO2 laser/waterjet (CO2-LWJ) cutting of Polycrystalline Cubic Boron Nitride (PCBN) blanks with phase transformation induced fracture (United States)

    Wu, Zhuoru; Melaibari, Ammar A.; Molian, Pal; Shrotriya, Pranav


    The present paper investigates a transformation induced fracture mechanism for the cutting of Polycrystalline Cubic Boron Nitride (PCBN) sample by a hybrid CO2 laser/waterjet (CO2-LWJ) manufacturing process. In CO2-LWJ machining, a laser was used for local heating followed by waterjet quenching leading to fracture propagation along the sample surface. Cutting results indicate that as line energy of the laser was increased the sample response transitioned from scribing to through cutting. Raman spectroscopy analysis of the cut surface indicates that laser heated PCBN undergoes chemical phase transformation from sp3-bonded cubic Boron Nitride (cBN) into hexagonal Boron Nitride (hBN) and other sp2-bonded phases. The sp2-bonded structure occupies more volume than sp3-bonded structure such that the transformed material has a tendency to expand the original material and leads to surface deformation around the cutting path. Surface profile of the cut samples was experimentally measured using profilometry and compared with numerical predictions in order to estimate the expansion strain and dimensions of transformation region. Based on the obtained expansion strain and transformation zone, stress fields and crack driving forces were computed for channeling cracks that result in material separation. Comparison of the crack driving forces with fracture toughness of PCBN shows that transformation induced crack propagation is the feasible mechanism for cutting during CO2-LWJ machining.

  2. Caries inhibition in vital teeth using 9.6-μm CO2-laser irradiation (United States)

    Rechmann, Peter; Fried, Daniel; Le, Charles Q.; Nelson, Gerald; Rapozo-Hilo, Marcia; Rechmann, Beate M. T.; Featherstone, John D. B.


    The aim of this study was to test the hypothesis that in a short-term clinical pilot trial short-pulsed 9.6 μm CO2-laser irradiation significantly inhibits demineralization in vivo. Twenty-four subjects scheduled for extraction of bicuspids for orthodontic reasons (age 14.9 +/- 2.2 years) were recruited. Orthodontic brackets were placed on bicuspids (Transbond XT, 3M). An area next to the bracket was irradiated with a CO2-laser (Pulse System Inc, Los Alamos, New Mexico), wavelength 9.6 μm, pulse duration 20 μs, pulse repetition rate 20 Hz, beam diameter 1100 μm, average fluence 4.1 +/- 0.3J/cm2, 20 laser pulses per spot. An adjacent nonirradiated area served as control. Bicuspids were extracted after four and twelve weeks, respectively, for a quantitative assessment of demineralization by cross-sectional microhardness testing. For the 4-week arm the mean relative mineral loss ΔZ (vol% × μm) for the laser treated enamel was 402 +/- 85 (mean +/- SE), while the control showed significantly higher mineral loss (ΔZ 738 +/- 131; P = 0.04, t-test). The difference was even larger after twelve weeks (laser arm ΔZ 135 +/- 98; control 1067 +/- 254; P = 0.002). The laser treatment produced 46% demineralization inhibition for the 4-week and a marked 87% inhibition for the 12-week arm. This study shows, for the first time in vivo, that the short-pulsed 9.6 μm CO2-laser irradiation successfully inhibits demineralization of tooth enamel in humans.

  3. Recurrence rate and patient satisfaction of CO2 laser evaporation of lesions in patients with hidradenitis suppurativa

    DEFF Research Database (Denmark)

    Mikkelsen, Peter Riis; Dufour, Deirde Nathalie; Zarchi, Kian


    : To determine the recurrence rate, time to recurrence, and factors influencing disease recurrence in skin treated with CO2 laser evaporation, and healing by secondary intention; and patients' satisfaction with treatment. METHODS: Fifty-eight patients treated with CO2 laser evaporation were interviewed regarding...

  4. Diffusion of Co and W in diamond tool induced by 10.6 µm CO2 laser radiation

    CSIR Research Space (South Africa)

    Masina, Bathusile N


    Full Text Available Experimental setup CO2 laser ZnSe lens, f = 250 mm HPHT diamond sample Infrared camera Slide 8 © CSIR 2009 Experimental setup CO2 laser ZnSe lens, f = 250 mm HPHT diamond sample Infrared camera...

  5. CO2 Laser (10.6 microm) parameters for caries prevention in dental enamel. (United States)

    Esteves-Oliveira, M; Zezell, D M; Meister, J; Franzen, R; Stanzel, S; Lampert, F; Eduardo, C P; Apel, C


    Although CO(2) laser irradiation can decrease enamel demineralisation, it has still not been clarified which laser wavelength and which irradiation conditions represent the optimum parameters for application as preventive treatment. The aim of the present explorative study was to find low-fluence CO(2) laser (lambda = 10.6 microm) parameters resulting in a maximum caries-preventive effect with the least thermal damage. Different laser parameters were systematically evaluated in 3 steps. In the first experiment, 5 fluences of 0.1, 0.3, 0.4, 0.5 and 0.6 J/cm(2), combined with high repetition rates and 10 micros pulse duration, were chosen for the experiments. In a second experiment, the influence of different pulse durations (5, 10, 20, 30 and 50 micros) on the demineralisation of dental enamel was assessed. Finally, 3 different irradiation times (2, 5 and 9 s) were tested in a third experiment. In total, 276 bovine enamel blocks were used for the experiments. An 8-day pH-cycling regime was performed after the laser treatment. Demineralisation was assessed by lesion depth measurements with a polarised light microscope, and morphological changes were assessed with a scanning electron microscope. Irradiation with 0.3 J/cm(2), 5 micros, 226 Hz for 9 s (2,036 overlapping pulses) increased caries resistance by up to 81% compared to the control and was even significantly better than fluoride application (25%, p laser irradiation. (c) 2009 S. Karger AG, Basel.

  6. An audit of the use of the CO2 laser in oral and maxillofacial surgery (United States)

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


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

  7. Analysis of the Damage Mechanism Related to CO2 Laser Cochleostomy on Guinea Pig Cochlea

    Directory of Open Access Journals (Sweden)

    Xiang Liu


    Full Text Available Different types of lasers have been used in inner ear surgery. Therefore, it is of the utmost importance to avoid damage to the inner ear (e.g., hyperthermia and acoustic effects caused by the use of such lasers. The aim of this study was to use a high powered fibre-enabled CO2 laser (10 W, 606 J/cm2 to perform cochleostomies on guinea pig cochlea and to investigate the possible laser-induced damage mechanisms. The temperature changes in the round window membrane, auditory evoked brainstem response, and morphological of the hair cells were measured and recorded before and after laser application. All of the outcomes differed in comparison with the control group. A rise in temperature and subsequent increased hearing loss were observed in animals that underwent surgery with a 10 W CO2 laser. These findings correlated with increased injury to the cochlear ultrastructure and a higher positive expression of E-cadherin and β-catenin in the damaged organ of Corti. We assume that enhanced cell-cell adhesion and the activated β-catenin-related canonical Wnt-signalling pathway may play a role in the protection of the cochlea to prevent further damage.

  8. An attemp to use a pulsed CO2 laser for decontamination of radioactive metal surfaces

    Directory of Open Access Journals (Sweden)



    Full Text Available There is a growing interest in laser radioactive decontamination of metal surfaces. It offers advantages over conventional methods: improved safety, reduction of secondary waste, reduced waste volume, acceptable cost. The main mechanism of cleaning by lasers is ablation. A pulsed TEA CO2 laser was used in this work for surface cleaning in order to show that ablation of metal surfaces is possible even at relatively low pulse energies, and to suggest that it could be competitive with other lasers because of much higher energy efficiencies. A brief theoretical analysis was made before the experiments. The laser beam was focused using a KBr-lens onto a surface contaminated with 137Cs (b-, t1/2 = 30.17 y. Three different metals were used: stainless steel, copper and aluminium. The ablated material was pumped out in an air atmosphere and transferred to a filter. The presence of activity on the filter was shown by a germanium detector-multichannel analyzer. The activity levels were measured by a GM counter. The calculated decontamination factors and collection factors showed that ablation occurs with a relatively high efficiency of decontamination. This investigation suggests that decontamination using a CO2 laser should be seriously considered.

  9. Parameter optimization for selective laser melting of TiAl6V4 alloy by CO2 laser (United States)

    Baitimerov, R. M.; Lykov, P. A.; Radionova, L. V.; Safonov, E. V.


    TiAl6V4 alloy is one of the widely used materials in powder bed fusion additive manufacturing technologies. In recent years selective laser melting (SLM) of TiAl6V4 alloy by fiber laser has been well studied, but SLM by CO2-lasers has not. SLM of TiAl6V4 powder by CO2-laser was studied in this paper. Nine 10×10×10 mm cubic specimens were fabricated using different SLM process parameters. All of the fabricated specimens have a good dense structure and a good surface finish quality without dimensional distortion. The lowest porosity that was achieved was about 0.5%.

  10. Fractional CO 2 laser resurfacing as monotherapy in the treatment of atrophic facial acne scars

    Directory of Open Access Journals (Sweden)

    Imran Majid


    Full Text Available Background: While laser resurfacing remains the most effective treatment option for atrophic acne scars, the high incidence of post-treatment adverse effects limits its use. Fractional laser photothermolysis attempts to overcome these limitations of laser resurfacing by creating microscopic zones of injury to the dermis with skip areas in between. Aim: The aim of the present study is to assess the efficacy and safety of fractional CO 2 laser resurfacing in atrophic facial acne scars. Materials and Methods: Sixty patients with moderate to severe atrophic facial acne scars were treated with 3-4 sessions of fractional CO 2 laser resurfacing at 6-week intervals. The therapeutic response to treatment was assessed at each follow up visit and then finally 6 months after the last laser session using a quartile grading scale. Response to treatment was labelled as ′excellent′ if there was >50% improvement in scar appearance and texture of skin on the grading scale while 25-50% response and <25% improvement were labelled as ′good′ and ′poor′ response, respectively. The overall satisfaction of the patients and any adverse reactions to the treatment were also noted. Results: Most of the patients showed a combination of different morphological types of acne scars. At the time of final assessment 6 months after the last laser session, an excellent response was observed in 26 patients (43.3% while 15 (25% and 19 patients (31.7% demonstrated a good and poor response respectively. Rolling and superficial boxcar scars responded the best while pitted scars responded the least to fractional laser monotherapy. The commonest reported adverse effect was transient erythema and crusting lasting for an average of 3-4 and 4-6 days, respectively while three patients developed post-inflammatory pigmentation lasting for 8-12 weeks. Conclusions: Fractional laser resurfacing as monotherapy is effective in treating acne scars especially rolling and superficial boxcar

  11. Analysis of the heat affected zone in CO2 laser cutting of stainless steel

    Directory of Open Access Journals (Sweden)

    Madić Miloš J.


    Full Text Available This paper presents an investigation into the effect of the laser cutting parameters on the heat affected zone in CO2 laser cutting of AISI 304 stainless steel. The mathematical model for the heat affected zone was expressed as a function of the laser cutting parameters such as the laser power, cutting speed, assist gas pressure and focus position using the artificial neural network. To obtain experimental database for the artificial neural network training, laser cutting experiment was planned as per Taguchi’s L27 orthogonal array with three levels for each of the cutting parameter. Using the 27 experimental data sets, the artificial neural network was trained with gradient descent with momentum algorithm and the average absolute percentage error was 2.33%. The testing accuracy was then verified with 6 extra experimental data sets and the average predicting error was 6.46%. Statistically assessed as adequate, the artificial neural network model was then used to investigate the effect of the laser cutting parameters on the heat affected zone. To analyze the main and interaction effect of the laser cutting parameters on the heat affected zone, 2-D and 3-D plots were generated. The analysis revealed that the cutting speed had maximum influence on the heat affected zone followed by the laser power, focus position and assist gas pressure. Finally, using the Monte Carlo method the optimal laser cutting parameter values that minimize the heat affected zone were identified.

  12. Side-pumped Nd:YVO4 cw laser with grazing-incidence small angle configuration

    International Nuclear Information System (INIS)

    Camargo, Fabiola de Almeida


    Within the existing variety of laser cavity geometries and gain materials there is one combination that is particularly interesting because of its reduced complexity and high efficiency: the edge-pumped slab-laser using grazing-incidence geometry and a gain media with a very high pump absorption cross-section. In this work we studied a diode side-pumped Nd:YVO 4 cw laser. We describe a single and a multiple bounce laser configurations. We demonstrate 22 W of multimode output power for 35 watts of pump power with a single pass through the gain media. A high optical-to-optical conversion efficiency of 63% and a slope efficiency of 74% with a very compact and simple Nd:YVO 4 cavity that uses joint stability zones was achieved. The beam quality was M 2 = 26 x 11 in the horizontal and vertical direction, respectively. With a double pass configuration we achieved 17 watts with a better beam quality of M 2 = 3,4 x 3,7, in the horizontal and vertical direction, respectively. (author)

  13. Optical Probing of CO2 Laser-Plasma Interactions at Near Critical Density (United States)

    Gong, Chao

    The interaction of a high-power laser beam with plasma has been explored extensively in the context of laser-driven fusion, plasma-based acceleration of ions and electrons and high energy-density physics. One of the fundamental processes common to all these studies is the penetration of intense light into a dense matter through the hole boring effect and self-induced transparency. Light with a given wavelength lambda will be reflected once the electron density equals the critical electron plasma density nc = 1.1x 1021cm -3 /[lambda(mum)]2. The radiation pressure exerted on the critical density layer is characterized by the ponderomotive force of a focused laser pulse which scales with a laser intensity, I as Ilambda2 Wmum2/cm 2. At Ilambda2 ˜1017 Wmum2/cm2 and above, it becomes possible for the laser pulse not only to steepen the plasma profile but to push the overcritical plasma with ne > nc creating a cavity or a hole in the target. The phenomenon of hole boring, whereby a laser pulse propagates through a reduced density cavity to reach and push the critical density layer, is of importance in fast-ignition fusion because it may allow the laser pulse to deliver its energy closer to the compressed fuel where it can be converted into fast electrons that are needed to ignite a small portion of the fuel. The layer of plasma pushed by the radiation pressure can reflect and accelerate ions via the so called Hole Boring Radiation Pressure Acceleration mechanism. Also the density pile- up in combination with the strong electron heating at the critical density layer can facilitate the formation of a collisionless shock. This shock wave acceleration can produce high energy ion beams with a narrow energy spread. Numerous experiments have been carried out to study dynamics of laser plasma interaction indirectly using solid state targets that are opaque for 1?m laser. However, by using a longer wavelength CO2 laser, lambda = 10.6mum, the critical plasma density is decreased

  14. 13CO2/12CO2 isotope ratio analysis in human breath using a 2 μm diode laser (United States)

    Sun, Mingguo; Cao, Zhensong; Liu, Kun; Wang, Guishi; Tan, Tu; Gao, Xiaoming; Chen, Weidong; Yinbo, Huang; Ruizhong, Rao


    The bacterium H. pylori is believed to cause peptic ulcer. H. pylori infection in the human stomach can be diagnosed through a CO2 isotope ratio measure in exhaled breath. A laser spectrometer based on a distributed-feedback semiconductor diode laser at 2 μm is developed to measure the changes of 13CO2/12CO2 isotope ratio in exhaled breath sample with the CO2 concentration of ~4%. It is characterized by a simplified optical layout, in which a single detector and associated electronics are used to probe CO2 spectrum. A new type multi-passes cell with 12 cm long base length , 29 m optical path length in total and 280 cm3 volume is used in this work. The temperature and pressure are well controlled at 301.15 K and 6.66 kPa with fluctuation amplitude of 25 mK and 6.7 Pa, respectively. The best 13δ precision of 0.06o was achieved by using wavelet denoising and Kalman filter. The application of denoising and Kalman filter not only improved the signal to noise ratio, but also shorten the system response time.

  15. Oral Crest Lengthening for Increasing Removable Denture Retention by Means of CO2 Laser

    Directory of Open Access Journals (Sweden)

    Samir Nammour


    Full Text Available The loss of teeth and their replacement by artificial denture is associated with many problems. The denture needs a certain amount of ridge height to give it retention and a long-term function. Crest lengthening procedures are performed to provide a better anatomic environment and to create proper supporting structures for more stability and retention of the denture. The purpose of our study is to describe and evaluate the effectiveness of CO2 laser-assisted surgery in patients treated for crest lengthening (vestibular deepening. There have been various surgical techniques described in order to restore alveolar ridge height by pushing muscles attaching of the jaws. Most of these techniques cause postoperative complications such as edemas, hemorrhage, pain, infection, slow healing, and rebound to initial position. Our clinical study describes the treatment planning and clinical steps for the crest lengthening with the use of CO2 laser beam (6–15 Watts in noncontact, energy density range: 84.92–212.31 J/cm2, focus, and continuous mode with a focal point diameter of 0.3 mm. At the end of each surgery, dentures were temporarily relined with a soft material. Patients were asked to mandatorily wear their relined denture for a minimum of 4–6 weeks and to remove it for hygienic purposes. At the end of each surgery, the deepest length of the vestibule was measured by the operator. No sutures were made and bloodless wounds healed in second intention without grafts. Results pointed out the efficiency of the procedure using CO2 laser. At 8 weeks of post-op, the mean of crest lengthening was stable without rebound. Only a loss of 15% was noticed. To conclude, the use of CO2 laser is an effective option for crest lengthening.

  16. Experimental observation of parametric effects near period doubling in a loss-modulated CO2 laser


    Chizhevsky, V. N.


    A number of parametric effects, such as suppression of period doubling, shift of the bifurcation point, scaling law relating the shift and the perturbation amplitude, influence of the detuning on the suppression, reaching of the maximum gain between the original and shifted bifurcation points, and scaling law for idler power are experimentally observed near period doubling bifurcation in a loss-driven CO2 laser that is subjected to periodic loss perturbations at a frequency that is close to a...

  17. Complications of endoscopic CO2 laser surgery for laryngeal cancer and concepts of their management.


    Prgomet, Drago; Bačić, Antun; Prstačić, Ratko; Janjanin, Saša


    Endoscopic CO 2 laser surgery (ELS) is a widely accepted treatment modality for early laryngeal cancer. Commonly re- ported advantages of ELS are good oncologic results with low incidence of complications. Although less common if com- pared with open procedures, complications following ELS can be very serious, even with lethal outcome. They can range from intraoperative endotracheal tube fire accidents to early and late postoperative sequels that require intensive medical treatment, blood tra...

  18. HgCdTe photomixers for CO2 laser radar systems (United States)

    Bratt, Peter R.


    The Santa Barbara Research Center has developed a variety of high speed HgCdTe photodetectors for use in CO2 laser radar systems. These detectors have outstanding performance and can be made available in production quantities. Many of them have been employed in a variety of systems applications over the past ten years. In this paper, we briefly describe the detector technology, summarize the state-of-the-art, and indicate some practical applications.

  19. Comparison of surface roughness quality created by abrasive water jet and CO2 laser beam cutting

    Czech Academy of Sciences Publication Activity Database

    Zeleňák, M.; Valíček, Jan; Klich, Jiří; Židková, P.


    Roč. 19, č. 3 (2012), s. 481-485 ISSN 1330-3651 R&D Projects: GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : abrasive waterjet cutting * CO2 laser beam cutting * optical profilometry * titanium sample Subject RIV: JQ - Machines ; Tools Impact factor: 0.601, year: 2012

  20. Alignment control of columnar liquid crystals with wavelength tunable CO2 laser irradiation

    International Nuclear Information System (INIS)

    Monobe, Hirosato; Awazu, Kunio; Shimizu, Yo


    Infrared-induced alignment change with wavelength tunable CO 2 laser irradiation for columnar liquid crystal domains was investigated for a liquid crystalline triphenylene derivative. A uniformly aligned alignment change of domains was observed when a chopped linearly polarized infrared laser light corresponding to the wavelength of the aromatic C-O-C stretching vibration band (9.65 μm) was irradiated. The results strongly imply that the infrared irradiation is a possible technique for device fabrication by use of columnar mesophase as a liquid crystalline semiconductor

  1. CO2-laser--produced plasma columns in a solenoidal magnetic field

    International Nuclear Information System (INIS)

    Offenberger, A.A.; Cervenan, M.R.; Smy, P.R.


    A 1-GW CO 2 laser pulse has been used to produce extended column breakdown of hydrogen at low pressure in a 20-cm-long solenoid. Magnetic fields of up to 110 kG were used to inhibit radial losses of the plasma column. A differential pumping scheme was devised to prevent formation of an opaque absorption wave travelling out of the solenoid back toward the focusing lens. Target burns give direct evidence for trapped laser beam propagation along the plasma column

  2. Dispersion of light and heavy pollutants in urban scale models: CO(2) laser photoacoustic studies. (United States)

    Zelinger, Z; Strizík, M; Kubát, P; Civis, S; Grigorová, E; Janecková, R; Zavila, O; Nevrlý, V; Herecová, L; Bailleux, S; Horká, V; Ferus, M; Skrínský, J; Kozubková, M; Drábková, S; Janour, Z


    The distribution of pollutants in two urban scale models (point emission source and street canyon with extensive transport) was investigated by means of CO(2) laser photoacoustic spectroscopy in the region of the atmospheric window (9-10 mum). The experimental results of physical modeling are in a good agreement with the numerical calculations performed in the frame of computational fluid dynamic (CFD) modeling. Methanol, ethanol, and ozone (examples of light pollutants), as well as sulfur hexafluoride and 1,2 dichlorethane (examples of heavy pollutants), were selected on the basis of their high resolution spectra acquired by Fourier transform and laser diode spectroscopy.

  3. Design of an Optical System for High Power CO2 Laser Cutting

    DEFF Research Database (Denmark)

    de Lange, D.F.; Meijer, J.; Nielsen, Jakob Skov


    The results of a design study for the optical system for cutting with high power CO2 lasers (6 kW and up) will be presented. As transparent materials cannot be used for these power levels, mirrors have been applied. A coaxial cutting gas supply has been designed with a laser beam entrance into th...... pressured gas chamber, by means of an intermediate focus. It allows the beam to enter the gas chamber through a small nozzle opening. The final optical system consists of two off-axis aspherical mirrors. In general aspherical elements are very sensitive for positional or angular errors, resulting...

  4. HRR TEA CO2 laser with 220W average output power

    Directory of Open Access Journals (Sweden)

    M. Zand


    Full Text Available In this study, the design and construction of a pulse high repetition rate (HRR, transverse atmospheric pressure (TEA CO2 laser with ultra violet preionization is presented. In this laser, normal pure, industrial gases and also a combination of spark and corona preionization are used. In semi-sealed off condition, we obtained 220 watts at 300 Hz, %7.7 efficiency, 735 mJ/pulse. The best records that we reached separately were 1.1 J/pulse, 320 Hz PRR, 11 MW peak power and 10.6% efficiency .

  5. Effect of the operating characteristics parameters on the performance of a waveguide CO2 laser (United States)

    Mortazavi, Somayeh; Sajad, Batol; Jelvani, Saeid; Pazokian, Hedieh; Montazerolghaem, Mohsen; Naeimi, Saeid Amin


    In this paper, the influence of the operating parameters on the performance of a waveguide-CO2 laser was investigated. The output power versus discharge current, gas pressure, and gas mixture ratio were measured using a different tube design. Also, it is observed that the laser output wavelengths vary as the discharge current changes. The obtained maximum powers are ~14.5 W in a tube of diameter 3 mm and length 70 cm at the pressure 50 mbar, using the active medium with two discharge regions.

  6. Pulsed CO2 laser interaction with a metal surface at oblique incidence (United States)

    McKay, J. A.; Schriempf, J. T.; Cronburg, T. L.; Eninger, J. E.; Woodroffe, J. A.


    Thermal fluence deposition and surface pressure generation produced by a CO2 laser pulse have been measured as a function of angle of incidence theta on sheet aluminum in air. The paper finds that air plasma ignition depends on the laser beam intensity I sub 0 only, not on the surface-normal flux (I sub 0)(cos theta). Conversely, the fluence deposition and surface pressure depend only on the product (I sub 0)(cos theta), and obey the square-root and two-thirds-power dependences observed with simple I sub 0 variation at normal incidence.

  7. Dispersion of Light and Heavy Pollutants in Urban Scale Models: CO2 Laser Photoacoustic Studies

    Czech Academy of Sciences Publication Activity Database

    Zelinger, Zdeněk; Střižík, M.; Kubát, Pavel; Civiš, Svatopluk; Grigorová, E.; Janečková, R.; Zavila, O.; Nevrlý, Václav; Herecová, L.; Bailleux, S.; Horká-Zelenková, Veronika; Ferus, Martin; Skříňský, J.; Kozubková, M.; Drábková, S.; Jaňour, Zbyněk


    Roč. 63, č. 4 (2009), s. 430-436 ISSN 0003-7028 R&D Projects: GA MŠk OC 111; GA MŠk LC06071; GA ČR GA202/06/0216; GA MŽP SPII1A0/45/07 Institutional research plan: CEZ:AV0Z40400503; CEZ:AV0Z20760514 Keywords : Air pollution * CO2 laser photoacoustic spectroscopy * PAS * Laser diode spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.564, year: 2009

  8. Fabrication of Nanostructured Omniphobic and Superomniphobic Surfaces with Inexpensive CO2Laser Engraver. (United States)

    Pendurthi, Anudeep; Movafaghi, Sanli; Wang, Wei; Shadman, Soran; Yalin, Azer P; Kota, Arun K


    Superomniphobic surfaces (i.e., surfaces that are extremely repellent to both high surface tension liquids like water and low surface tension liquid like oils) can be fabricated through a combination of surface chemistry that imparts low solid surface energy with a re-entrant surface texture. Recently, surface texturing with lasers has received significant attention because laser texturing is scalable, solvent-free, and can produce a monolithic texture on virtually any material. In this work, we fabricated nanostructured omniphobic and superomniphobic surfaces with a variety of materials using a simple, inexpensive and commercially available CO 2 laser engraver. Further, we demonstrated that the nanostructured omniphobic and superomniphobic surfaces fabricated using our laser texturing technique can be used to design patterned surfaces, surfaces with discrete domains of the desired wettability, and on-surface microfluidic devices.

  9. Evaluation of CO2 laser irradiation effect on enamel microhardness after incipient caries creation

    Directory of Open Access Journals (Sweden)

    Loghman Rezaei-Soufi


    Full Text Available Objective: The important mission in modern science of caries prevention is identification and providing the necessary actions for caries prevention to patients with an elevated risk of caries. The aim of this study was evaluation of CO2 laser irradiation effect on enamel microhardness after incipient caries creation. Material and methods: In this in vitro-experimental study, for evaluation of enamel microhardness 30 teeth after disinfection process were divided randomly into three groups A, B, C [n=10]: A] Control [normal saline] B] Immersed in cariogenic solution for 1 month C] Immersed in cariogenic solution for 1 month + CO2 laser [10.6µm, 10Hz, 0.5W, 20s, beam diameter 0.2 mm]. Data analyzing was used by 16 SPSS software. Parametric one-way ANOVA and Tukey were used for surface microhardness at 0.05% significance level. Results: According to one-way ANOVA parametric test, there was a significant difference between three groups [p=0.047]. In the following, results of Tukey test showed that there was a significant statistical difference between the microhardness of control and other groups [P=0.038]. On the other hand, there wasn’t statistical difference between A, C and B, C group means [P>0.05]. Conclusion: These study findings showed that CO2 laser irradiation on enamel surface with incipient caries had no significant effect on surface microhardness enhancement.

  10. Feasibility study of a CO2-laser based lightning-protection system realization (United States)

    Apollonov, Victor V.


    The feasibility of producing a continuous laser spark (CLS) with low resistance by focusing radiation from a CO2 laser with a conic mirror is demonstrated. The laser energy input per unit length required for this is experimentally found to be equal to ≈200 J/m. The possibility to efficiently control the trajectory of an electric discharge by means of a CLS is demonstrated. The effect of polarity in the electric breakdown of the air gaps between the CLS plasma channel and a metal rod is discovered and interpreted. The transverse structure of CLS conductivity is investigated. The possibility of producing a long laser spark (LLS) with much higher resistance by focusing radiation from a CO2 laser with a spherical mirror used to protect objects against lightning is studied. The conditions under which the electric discharges from clouds can be guided reproducibly along a LLS are determined. Experiments reveal that the interaction between the LLS and the discharge from an electrode (lightning rod) leads to a decrease in the lifetime of the streamer corona burst, as well as to an increase in the current of the developing leader and its velocity compared to the case without the LLS.

  11. CO2 laser surface treatment of failed dental implants for re-implantation: an animal study. (United States)

    Kasraei, Shahin; Torkzaban, Parviz; Shams, Bahar; Hosseinipanah, Seyed Mohammad; Farhadian, Maryam


    The aim of the present study was to evaluate the success rate of failed implants re-implanted after surface treatment with CO2 laser. Despite the widespread use of dental implants, there are many incidents of failures. It is believed that lasers can be applied to decontaminate the implant surface without damaging the implant. Ten dental implants that had failed for various reasons other than fracture or surface abrasion were subjected to CO2 laser surface treatment and randomly placed in the maxillae of dogs. Three failed implants were also placed as the negative controls after irrigation with saline solution without laser surface treatment. The stability of the implants was evaluated by the use of the Periotest values (PTVs) on the first day after surgery and at 1, 3, and 6 months post-operatively. The mean PTVs of treated implants increased at the first month interval, indicating a decrease in implant stability due to inflammation followed by healing of the tissue. At 3 and 6 months, the mean PTVs decreased compared to the 1-month interval (P laser surface debridement is associated with a high success rate in terms of implant stability.

  12. Measurements of Atmospheric CO2 Column in Cloudy Weather Conditions using An IM-CW Lidar at 1.57 Micron (United States)

    Lin, Bing; Obland, Michael; Harrison, F. Wallace; Nehrir, Amin; Browell, Edward; Campbell, Joel; Dobler, Jeremy; Meadows, Bryon; Fan, Tai-Fang; Kooi, Susan; hide


    This study evaluates the capability of atmospheric CO2 column measurements under cloudy conditions using an airborne intensity-modulated continuous-wave integrated-path-differential-absorption lidar operating in the 1.57-m CO2 absorption band. The atmospheric CO2 column amounts from the aircraft to the tops of optically thick cumulus clouds and to the surface in the presence of optically thin clouds are retrieved from lidar data obtained during the summer 2011 and spring 2013 flight campaigns, respectively.

  13. Cr-ni thermopile sensor for cw-laser power Measurement

    International Nuclear Information System (INIS)

    Garcia, M. A.; Darias, J. G.; Lubian, H.; Martin, J.L.


    In the present paper the manufacturing and characterization of a Cr-Ni thermopile sensor for CW-laser power measurements is described. The sensor was obtained using the vacuum evaporation method. We have chosen a thin film approach because it gives more flexibility in the design of the elements and in the choice of materials. The substrate of the sensitive element is a 1mm thick ceramic disk having a diameter of 40 mm. The thermopile metals were chosen for two reasons: (1) They have good thermocouple properties and (2) the evaporated films are tough and adherent. The geometry of the 11-junction thermopiles sufficiently coarse to allow fabrication of the thermopiles by successive evaporations through registering masks. The sensor is capable of power measurements of 1 to 30 watt and this version has a sensibility of 350 mV/W

  14. Remote wind sensing with a CW diode laser lidar beyond the coherence regime

    DEFF Research Database (Denmark)

    Hu, Qi; Rodrigo, Peter John; Pedersen, Christian


    optical designs but different laser linewidths. While one system was operating within the coherence regime, the other was measuring at least 2.4 times the coherence range. The probing distance of both lidars is 85 m and the radial wind speed correlation was measured to be r2=0.965 between the two lidars......We experimentally demonstrate for the first time (to our knowledge) a coherent CW lidar system capable of wind speed measurement at a probing distance beyond the coherence regime of the light source. A side-by-side wind measurement was conducted on the field using two lidar systems with identical...... at a sampling rate of 2 Hz. Based on our experimental results, we describe a practical guideline for designing a wind lidar operating beyond the coherence regime....

  15. Skin resurfacing improved with a new dual wavelength Er:YAG/CO2 laser system: a comparative study. (United States)

    Trelles, M A; García-Solana, L; Calderhead, R G


    The efficacy of a new dual wavelength Er:YAG and CO2 laser system was tested for skin resurfacing results on rabbits' ears and human facial skin. The dual wavelength laser delivers simultaneous pulses of low-energy CO2 and high-energy Er:YAG energies. Theoretically, combining the strengths of both laser types in one console should lead to improved clinical outcome. The use of the laser for skin resurfacing and remodeling has dramatically increased over the past few years. The CO2 laser was the first laser to be used in this field, followed more recently by the E:YAG laser. Both lasers offer unique advantages and disadvantages. The present study consists of an ear chamber experiment, conducted on eight rabbits, to examine vascular network formation, after laser resurfacing with a standard CO2 laser and the Er:YAG/CO2 laser. Resurfacing was also performed on human patients with the Er:YAG/CO2 laser and the results were compared with previously published results of CO2 laser resurfacing. Significant advantages, including an attenuation in the degree of edema and erythema and a shorter reepithelialization time compared to results with conventional CO2 systems, were observed with the Er:YAG/CO2 system. Improved tissue reorganization and good clinical results in nine of the ten patients (six ratings of "very good" and three "good") were observed. The clinical outcome of the remaining patient was rated as "fair." Minimal side effects were reported and observed in only three patients. The learning curve required to maximize the efficiency of the system is steep, however, requiring a thorough understanding of the different laser/tissue interactions associated with the two wavelengths. It is the authors' opinion that the dual wavelength Er:YAG/CO2 laser system offers a particularly efficient and flexible system to perform standard CO2 procedures for skin resurfacing with an improved clinical outcome, as well as other applications with the CO2 or Er:YAG energy delivered

  16. Investigation of flexible perforation of thin materials using a continuous-wave CO2 laser (United States)

    Xia, Linglin; Chen, Peifeng; Wang, Ying; Luo, Xi; Chao, Chuang


    Thin material laser perforation improves the flexibility and quality of materials such as tipping paper, medicated sticking plaster and breathable plastic film for storage. Perforation processing requires reliable, high speed, robust and adaptable optoelectronic systems to provide controllable permeability and flexibility in thin materials. This article provides descriptions on the design and performance of a new laser perforation system developed to meet such stringent requirements. This system is applicable for on-line thin material perforation. The optoelectronics include a continuous wave CO2 laser whose beam can be modulated into sequences of pulsed laser beams by a mechanical chopper. The focusing characteristics of a real laser beam in the perforation system have been investigated. This allowed laser beams to be focused on the moving thin material to be perforated and adaptable software control to provide the desired pattern distribution of the circular holes perforated on this material. A galvanometer scanner system allows sequential scanning of pulsed laser beams. This unique optoelectronic, mechanical and dedicated embedded control system has been designed and implemented to synchronize the actions of mechanical choppers, galvanometer scanners and the movement characteristics of the thin material. A practical implementation of the sticking plaster and tipping paper laser perforation system has been completed and successfully tested. Results show for example that circular holes with two geometrical distribution patterns are achievable, and unique patterns of perforation can be designed to discourage counterfeiting.

  17. Cold cathode electron guns in the LASL high power short-pulse CO2 laser program

    International Nuclear Information System (INIS)

    Singer, S.; Ladish, J.S.; Nutter, M.J.


    The Electron Beam Controlled Discharge CO 2 Laser is now firmly established as the only high power short pulse laser amplifier that has been demonstrated to have scaling capabilities to large apertures and energies much greater than 100 J. These devices require a beam of energetic electrons to control the gas discharge that produces the required population inversion. Until recently, the electron source was usually a thermionic emitter, even for rather large lasers, whose heater requirements dwarfed the pulsed energies associated with the transient operation of the laser. With the advent of reliable cold-cathode electron guns, the operation of these lasers has been greatly simplified. At LASL, there are four electron beam controlled laser systems which are in operation, under construction, or in design: the 1 kJ system, now operational; the 2.5 kJ system; the 10 kJ system; and the 100 kJ system. Only the first uses thermionic-emitter electron guns; the remainder use or will use cold cathode sources. The operation of the 200 x 35 cm 2 two sided cold cathode electron gun used in the 2.5 kJ laser system and to be used in the 10 kJ laser is described

  18. Advanced 2-micron Solid-state Laser for Wind and CO2 Lidar Applications (United States)

    Yu, Jirong; Trieu, Bo C.; Petros, Mulugeta; Bai, Yingxin; Petzar, Paul J.; Koch, Grady J.; Singh, Upendra N.; Kavaya, Michael J.


    Significant advancements in the 2-micron laser development have been made recently. 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 (DIAL) system for measuring atmospheric CO2 concentration profiles. The world record 2-micron laser energy is demonstrated with an oscillator and two amplifiers system. It generates more than one joule per pulse energy with excellent beam quality. Based on the successful demonstration of a fully conductive cooled oscillator by using heat pipe technology, an improved fully conductively cooled 2-micron amplifier was designed, manufactured and integrated. It virtually eliminates the running coolant to increase the overall system efficiency and reliability. In addition to technology development and demonstration, a compact and engineering hardened 2-micron laser is under development. It is capable of producing 250 mJ at 10 Hz by an oscillator and one amplifier. This compact laser is expected to be integrated to a lidar system and take field measurements. The recent achievements push forward the readiness of such a laser system for space lidar applications. This paper will review the developments of the state-of-the-art solid-state 2-micron laser.

  19. Room temperature CW and QCW operation of Ho:CaF2 laser pumped by Tm:fiber laser (United States)

    Jelínek, Michal; Cvrček, Jan; Kubeček, Václav; Zhao, Beibei; Ma, Weiwei; Jiang, Dapeng; Su, Liangbi


    Laser radiation in the wavelength range around 2 μm is required for its specific properties - it is very suitable for medical applications, remote sensing, or pumping of optical parametric oscillators to generate ultrafast pulses in the mid-IR region further exploited in nonlinear optics. Crystals as YLF, YAG, LLF, and GdVO4 doped by holmium were already investigated and found suitable for the tunable laser generation around 2.1 mμ. Only a few works are devoted to the laser operation of holmium-doped fluorides as CaF2. In this work, pulsed and continuous-wave laser operation of a modified- Bridgman-grown Ho:CaF2 active crystal at room temperature is reported. A commercial 50 W 1940 nm Tm-fiber laser was used to pump a laser oscillator based on a novel 10 mm long 0.5 at.% Ho:CaF2 active crystal placed in the Peltiercooled holder. In the pulsed regime (10 ms, 10 Hz), the laser slope efficiency of 53 % with respect to the absorbed pump power was achieved. The laser generated at the central wavelength of 2085 nm with the maximum mean output power of 365 mW corresponding to the power amplitude of 3.65 W. In the continuous wave regime, the maximum output power was 1.11 W with the slope efficiency of 41 % with respect to the absorbed pump power. To our best knowledge this is the first demonstration of this laser active material operating in the CW regime at room temperature. The tuning range over 60 nm from 2034 to 2094 nm was achieved using a birefringent filter showing the possibility to develop a mode-locked laser system generating pulses in the sub-picosecond range.

  20. Safety and efficacy of high fluence CO2 laser skin resurfacing with a single pass. (United States)

    Khosh, M M; Larrabee, W F; Smoller, B


    Carbon dioxide (CO2) laser skin resurfacing has nearly replaced more traditional methods of superficial skin rejuvenation. Post-treatment erythema is the most common side effect of this method of skin resurfacing. Sublethal thermal damage to the dermis has been proposed as an etiology for post laser erythema. Recent developments in laser resurfacing technology have aimed at minimizing thermal damage to the dermis. To determine depth of skin ablation, extent of thermal injury, and ideal laser parameters for the FeatherTouch laser system. To assess the safety and efficacy of laser resurfacing at high energy fluences with a single pass. Laser resurfacing was performed in the preauricular skin of five patients undergoing rhytidectomy. A total of 60 sites were tested with fluences of 7 to 17 Joules/cm2. Histologic evaluation of excised skin showed maximal thermal injury to be restricted to 60 microns in the papillary dermis. The reticular dermis showed no evidence of injury. Based on these findings, laser resurfacing at 17 J/cm2 (70 watts) was performed on 30 patients (in the periorbital area, a maximum of 9 J/cm2 or 36 watts was used). Follow up ranged between 12 and 18 months. Based on histologic comparison of average and high fluence laser resurfacing, high fluence laser resurfacing did not cause added thermal damage to the reticular dermis. In the clinical group, no major complications such as scarring, scleral show, infection or ectropion were encountered. Transient hyperpigmentation was noted in three patients. Overall patient satisfaction was good to excellent. Post-treatment erythema lasted an average of 4 weeks. We conclude that CO2 laser resurfacing of the face (excluding the periorbital region) can be performed safely and effectively, with the FeatherTouch laser, at 17 J/cm2 with one pass. In our group of patients, laser resurfacing with a single pass at 17 J/cm2 caused less post-operative erythema than two or more passes at 9 J/cm2.

  1. Controllable generation and manipulation of micro-bubbles in water with absorptive colloid particles by CW laser radiation

    DEFF Research Database (Denmark)

    Angelsky, O. V.; Bekshaev, A. Ya.; Maksimyak, P. P.


    Micrometer-sized vapor-gas bubbles are formed due to local heating of a water suspension containing absorptive pigment particles of 100 nm diameter. The heating is performed by CW near-infrared (980 nm) laser radiation with controllable power, focused into a 100 mu m spot within a 2 mm suspension...

  2. High-pressure continuously tunable CO2 lasers and molecular laser ...

    Indian Academy of Sciences (India)


    Jan 5, 2014 ... The acronym MLIS (molecular laser isotope separation) defines the laser process whereby the isotopes of uranium can be separated by mid-infrared laser/s when the molecule employed is UF6. The theoretical and spectroscopical data to configure and enable experiments and demonstrations in the ...

  3. Demonstration of frequency control and CW diode laser injection control of a titanium-doped sapphire ring laser with no internal optical elements (United States)

    Bair, Clayton H.; Brockman, Philip; Hess, Robert V.; Modlin, Edward A.


    Theoretical and experimental frequency narrowing studies of a Ti:sapphire ring laser with no intracavity optical elements are reported. Frequency narrowing has been achieved using a birefringent filter between a partially reflecting reverse wave suppressor mirror and the ring cavity output mirror. Results of CW diode laser injection seeding are reported.

  4. Experimental studies on nonpenetrating filtration surgery using the CO2 laser. (United States)

    Assia, Ehud I; Rotenstreich, Yigal; Barequet, Irina S; Apple, David J; Rosner, Mordechai; Belkin, Michael


    This study evaluated the use of a CO2 laser for performing deep sclerectomy in nonpenetrating filtration surgery. Three experimental models were performed: enucleated sheep and cow eyes (n=18) to determine optimal irradiation parameters, live rabbit eyes (n=20) to test feasibility, and cadaver eyes (40 procedures in 20 eyes) to study effects in human eyes tissue. After a half-thickness scleral flap was created, deep sclerectomy was performed by CO2 laser applications on the scleral bed down to the trabeculo-Descemet's membrane. Fluid percolation was repeatedly achieved without penetration in sheep and cow eyes using scanned laser energy of 5-10 W at a pulse duration of 200 micros and a working distance of 35 cm. In live rabbits, deep sclerectomy was achieved without perforation in 19/20 eyes. Intraocular pressure was significantly decreased on the first postoperative day (10.3+/-5.1 mmHg lower, on average, than in the nonoperated fellow eye; PCO2 laser-assisted deep sclerectomy is a feasible and apparently safe procedure.

  5. Improvement of dermatochalasis and periorbital rhytides with a high-energy pulsed CO2 laser: a retrospective study. (United States)

    Alster, Tina S; Bellew, Supriya G


    Upper eyelid dermatochalasis is typically treated with excisional blepharoplasty. The role of the CO2 laser previously had been confined to that of a vaporizing, incisional, or hemostatic tool. Over the past several years, however, ablative CO2 laser skin resurfacing has been popularized as an adjunctive treatment to blepharoplasty to minimize periorbital rhytides through its vaporizing as well as skin-tightening action. To evaluate the safety and efficacy of a high-energy pulsed CO2 laser as a stand-alone treatment for dermatochalasis and periorbital rhytides. Sixty-seven patients (skin phototypes I-IV) with mild-to-severe upper eyelid dermatochalasis and periorbital rhytides received periocular CO2 laser skin treatment. Global assessment scores of dermatochalasis and rhytides were determined by a side-by-side comparison of periocular photographs preoperatively and 1, 3, and 6 months postoperatively. In addition, caliper measurements of upper eyelids before and 1, 3, and 6 months after treatment were obtained. Both dermatochalasis and periorbital rhytides were significantly improved after periocular CO2 laser skin resurfacing. Patients with more severe dermatochalasis and rhytides showed greater improvement after CO2 laser treatment than did those with mild or moderate involvement. Side effects were limited to erythema and transient hyperpigmentation. No scarring, hypopigmentation, or ectropion were observed. Periocular skin resurfacing with a CO2 laser can safely and effectively improve upper eyelid dermatochalasis and periorbital rhytides.

  6. Transformation of hydroxyapatite to fluorapatite by irradiation with high-energy CO2 laser. (United States)

    Meurman, J H; Hemmerlé, J; Voegel, J C; Rauhamaa-Mäkinen, R; Luomanen, M


    High-energy laser irradiation has been shown to cause crystalline transformations in apatites, which may lead to the formation of tricalcium phosphates with a resulting decrease in acid resistance. Depending on the nature and energy density of laser irradiation used, however, an increase of acid resistance of dental enamel has also been reported after laser irradiation. The aim of the present study was to investigate the phase transformation of hydroxyapatite (HA) to fluorapatite (FA) in a model system that incorporates sodium fluoride (NaF) into apatite structure by using laser irradiation. A CO2 laser was used at energy densities ranging from 21 to 500 J/cm2. Synthetic HA mixed with NaF (10:1) was the target of laser irradiation. The crystalline structures were then investigated using X-ray diffraction analysis. The results showed that a phase transformation of HA to FA could be realized, and that the threshold energy density needed was 38 J/cm2. Not only is the finding crystallographically important, but it also opens new perspectives for future research regarding the development of laser technology for clinical purposes.

  7. Surface treatment of dental porcelain: CO2 laser as an alternative to oven glaze. (United States)

    Sgura, Ricardo; Reis, Mariana Cavalcante; Hernandes, Antonio Carlos; de Abreu Fantini, Márcia Carvalho; Andreeta, Marcello Rubens Barsi; Medeiros, Igor Studart


    This work tested continuous CO2 laser as a surface treatment to dental porcelain and compared it to oven glaze (auto-glaze) by means of roughness and color parameters. Three commercial veneering porcelains with different crystalline content were tested: VM7, VM9, and VM13. Porcelain discs (3.5 × 2.0 mm, diameter × height) were sintered and had one side ground by a diamond bur (45 μm) simulating a chairside adjustment in a clinical office. Specimens (n = 7) were divided into the following groups: C--control (no treatment), G--auto-glaze (oven), and L--surface continuous irradiation with CO2 laser (Gem Laser, Coherent; λ = 10.6 μm). Laser was tested in three exposure times (3, 4, or 5 min) and two irradiances (45 and 50 W/cm(2)). Roughness parameters (Ra, Rz, and Rpm/Rz) were measured using a rugosimeter (Surftest 301, Mitutoyo). Color differences (ΔE) between the G and L groups were calculated (VITA Easyshade); ΔE values up to 3.3 were considered as not perceivable. A surface analysis was conducted by stereomicroscopy (Olympus SZ61) and SEM (Stereoscan 440, LEO). Crystalline content of specimens from groups C and L (50 W/cm(2), 5 min) was assessed by X-ray diffraction and then compared. Surface roughness (Ra and Rz) observed for laser-irradiated groups was similar to G for all studied porcelains. Rpm/Rz ratios were near 1.0 for all groups that indicated a sharp ridge profile for all specimens. Only one laser condition studied (50 W/cm(2), 3 min) from VM7 porcelain resulted in color difference (ΔE = 3.5) to G. Specimens irradiated with 50 W/cm(2) for 5 min presented the smoother surface observed by SEM, comparable to G. X-ray diffraction data revealed an increase in leucite crystallite size for VM9 and VM13 porcelains after laser treatment. Regarding roughness, continuous CO2 laser applied on porcelain surface was as effective as conventional oven auto-glaze.

  8. Fabrication of gold and silver nanoparticles with pulsed laser ablation under pressurized CO2 (United States)

    Machmudah, Siti; Wahyudiono; Takada, Noriharu; Kanda, Hideki; Sasaki, Koichi; Goto, Motonobu


    Pulsed laser ablation (PLA) has become a promising method for the synthesis of nanoclusters for photonics, electronics and medicine. In this work PLA in pressurized CO2 has been applied for fabrication of gold and silver nanoparticles. Laser ablation was performed with an excitation wavelength of 532 nm under various pressures (0.1-20 MPa), temperatures (40-80 °C) of CO2 medium and ablation times (1500-9000 s). On the basis of the experimental result, it follows that structures of gold (Au) and silver (Ag) nanoparticles were significantly affected by the changes in CO2 density. The structures of gold and silver nanoparticles also changed with an increase of ablation time. From a field-emission scanning electron microscopy (FE-SEM) image of the fabricated gold nano-structured particles on silicon wafer, it was seen that a network structure of smaller gold particles was fabricated. A similar morphology of particles fabricated from silver plate was observed. Silver particles contain nanoparticles with large-varied diameter ranging from 5 nm to 1.2 μm. The mechanism of nanoparticles fabrication could be observed as follows. Bigger gold/silver particles melted during the ablation process and then ejected smaller spherical nanoparticles, which formed nanoclusters attached on the molten particles.

  9. Fabrication of gold and silver nanoparticles with pulsed laser ablation under pressurized CO2

    International Nuclear Information System (INIS)

    Machmudah, Siti; Wahyudiono; Kanda, Hideki; Goto, Motonobu; Takada, Noriharu; Sasaki, Koichi


    Pulsed laser ablation (PLA) has become a promising method for the synthesis of nanoclusters for photonics, electronics and medicine. In this work PLA in pressurized CO 2 has been applied for fabrication of gold and silver nanoparticles. Laser ablation was performed with an excitation wavelength of 532 nm under various pressures (0.1–20 MPa), temperatures (40–80 °C) of CO 2 medium and ablation times (1500–9000 s). On the basis of the experimental result, it follows that structures of gold (Au) and silver (Ag) nanoparticles were significantly affected by the changes in CO 2 density. The structures of gold and silver nanoparticles also changed with an increase of ablation time. From a field-emission scanning electron microscopy (FE-SEM) image of the fabricated gold nano-structured particles on silicon wafer, it was seen that a network structure of smaller gold particles was fabricated. A similar morphology of particles fabricated from silver plate was observed. Silver particles contain nanoparticles with large-varied diameter ranging from 5 nm to 1.2 μm. The mechanism of nanoparticles fabrication could be observed as follows. Bigger gold/silver particles melted during the ablation process and then ejected smaller spherical nanoparticles, which formed nanoclusters attached on the molten particles. (paper)

  10. Fractional CO2 laser treatment for vulvovaginal atrophy symptoms and vaginal rejuvenation in perimenopausal women

    Directory of Open Access Journals (Sweden)

    Arroyo C


    Full Text Available César Arroyo HM Montepríncipe University Hospital Laser Unit, Madrid, Spain Background: This study investigated a novel fractional carbon dioxide (CO2 laser for treatment of symptoms associated with vulvovaginal atrophy (VVA in perimenopausal women.Methods: The study included 21 perimenopausal women (mean age 45±7 years treated three times by CO2 laser resurfacing and coagulation of the vaginal canal tissue and mucosal tissue of the introitus. Vaginal health index (VHI scores were computed by the investigator at baseline and follow-ups. Subjects reported on sexual function, satisfaction, and improvement with treatment. A visual analog scale was used to measure discomfort with treatment.Results: Vaginal health and subject assessment of vaginal symptoms improved with successive treatments. At 12 weeks following the third treatment, 82% of the patients showed a statistically significant improvement in VHI (P<0.05. Additionally, 81% of subjects reported improvement in sexual gratification, 94% reported improvement in vaginal rejuvenation, and 100% reported satisfaction with treatment. VHI improvement remained significant at 6–8 months after treatments (P<0.01. Most patients (97% reported no to mild discomfort with treatment. Responses were mild and transient following treatment, with itching being the most commonly reported (20% side effect.Conclusion: In this study, fractional CO2 laser treatment was associated with improvement of vaginal health and amelioration of symptoms of VVA, resulting in improved sexual function in perimenopausal women. Treatment time was quick, and there was minimal discomfort associated with treatment. Investigation of clinical outcome in a larger study population is warranted. Keywords: genitourinary syndrome of menopause, vaginal rejuvenation, stress urinary incontinence, collagen remodeling, sexual dysfunction, vulvovaginal atrophy

  11. CO2 laser coating of nanodiamond on aluminum using an annular beam

    International Nuclear Information System (INIS)

    Blum, Rodger; Molian, Pal


    Laser coating of nanodiamond (ND) on aluminum alloy A319 substrate was investigated using a diffraction-free ring beam. A 1000 W continuous wave CO 2 laser in the ring beam configuration heated the 25–35 μm thick electrostatically sprayed ND powder layers on aluminum surface, melted a very thin layer (10 μm) of aluminum in a controlled fashion and caused phase transition of ND to form 50–60 μm thick ND/diamond-like carbon (DLC) coating. Significant improvements in friction, wear resistance and surface finish were observed in the ring beam method over the traditional Gaussian beam method suggesting that these thick (50–60 μm) ND/DLC laser coatings can outperform the currently used thin (<4 μm) chemically vapor deposited DLC coatings for aluminum parts in automobiles.

  12. Proton- and x-ray beams generated by ultra-fast CO2 lasers for medical applications (United States)

    Pogorelsky, Igor; Polyanskiy, Mikhail; Yakimenko, Vitaly; Ben-Zvi, Ilan; Shkolnikov, Peter; Najmudin, Zulfikar; Palmer, Charlotte A. J.; Dover, Nicholas P.; Oliva, Piernicola; Carpinelli, Massimo


    Recent progress in using picosecond CO2 lasers for Thomson scattering and ion-acceleration experiments underlines their potentials for enabling secondary radiation- and particle- sources. These experiments capitalize on certain advantages of long-wavelength CO2 lasers, such as higher number of photons per energy unit, and favorable scaling of the electrons' ponderomotive energy and critical plasma density. The high-flux x-ray bursts produced by Thomson scattering of the CO2 laser off a counter-propagating electron beam enabled high-contrast, time-resolved imaging of biological objects in the picosecond time frame. In different experiments, the laser, focused on a hydrogen jet, generated monoenergetic proton beams via the radiation-pressure mechanism. The strong power-scaling of this regime promises realization of proton beams suitable for laser-driven proton cancer therapy after upgrading the CO2 laser to sub-PW peak power. This planned improvement includes optimizing the 10-μm ultra-short pulse generation, assuring higher amplification in the CO2 gas under combined isotopic- and power-broadening effects, and shortening the postamplification pulse to a few laser cycles (150-200 fs) via chirping and compression. These developments will move us closer to practical applications of ultra-fast CO2 lasers in medicine and other areas.

  13. Interaction of CO2 laser-modified nylon with osteoblast cells in relation to wettability

    International Nuclear Information System (INIS)

    Waugh, D.G.; Lawrence, J.; Morgan, D.J.; Thomas, C.L.


    It has been amply demonstrated previously that CO 2 lasers hold the ability to surface modify various polymers. In addition, it has been observed that these surface enhancements can augment the biomimetic nature of the laser irradiated materials. This research has employed a CO 2 laser marker to produce trench and hatch topographical patterns with peak heights of around 1 μm on the surface of nylon 6,6. The patterns generated have been analysed using white light interferometry, optical microscopy and X-ray photoelectron spectroscopy was employed to determine the surface oxygen content. Contact angle measurements were used to characterize each sample in terms of wettability. Generally, it was seen that as a result of laser processing the contact angle, surface roughness and surface oxygen content increased whilst the apparent polar and total surface energies decreased. The increase in contact angle and reduction in surface energy components was found to be on account of a mixed intermediate state wetting regime owing to the change in roughness due to the induced topographical patterns. To determine the biomimetic nature of the modified and as-received control samples each one was seeded with 2 x 10 4 cells/ml normal human osteoblast cells and observed after periods of 24 h and 4 days using optical microscopy and SEM to determine mean cell cover densities and variations in cell morphology. In addition, a haemocytometer was used to show that the cell count for the laser patterned samples had increased by up to a factor of 1.5 compared to the as-received control sample after 4 days of incubation. Significantly, it was determined that all laser-induced patterns gave rise to better cell response in comparison to the as-received control sample studied due to increased preferential cell growth on those surfaces with increased surface roughness.

  14. Contribution to the beam plasma material interactions during material processing with TEA CO2 laser radiation (United States)

    Jaschek, Rainer; Konrad, Peter E.; Mayerhofer, Roland; Bergmann, Hans W.; Bickel, Peter G.; Kowalewicz, Roland; Kuttenberger, Alfred; Christiansen, Jens


    The TEA-CO2-laser (transversely excited atmospheric pressure) is a tool for the pulsed processing of materials with peak power densities up to 1010 W/cm2 and a FWHM of 70 ns. The interaction between the laser beam, the surface of the work piece and the surrounding atmosphere as well as gas pressure and the formation of an induced plasma influences the response of the target. It was found that depending on the power density and the atmosphere the response can take two forms. (1) No target modification due to optical break through of the atmosphere and therefore shielding of the target (air pressure above 10 mbar, depending on the material). (2) Processing of materials (air pressure below 10 mbar, depending on the material) with melting of metallic surfaces (power density above 0.5 109 W/cm2), hole formation (power density of 5 109 W/cm2) and shock hardening (power density of 3.5 1010 W/cm2). All those phenomena are usually linked with the occurrence of laser supported combustion waves and laser supported detonation waves, respectively for which the mechanism is still not completely understood. The present paper shows how short time photography and spatial and temporal resolved spectroscopy can be used to better understand the various processes that occur during laser beam interaction. The spectra of titanium and aluminum are observed and correlated with the modification of the target. If the power density is high enough and the gas pressure above a material and gas composition specific threshold, the plasma radiation shows only spectral lines of the background atmosphere. If the gas pressure is below this threshold, a modification of the target surface (melting, evaporation and solid state transformation) with TEA-CO2- laser pulses is possible and the material specific spectra is observed. In some cases spatial and temporal resolved spectroscopy of a plasma allows the calculation of electron temperatures by comparison of two spectral lines.

  15. CO2laser stapedotomy safety: influence of laser energy and time on bone-conduction hearing levels. (United States)

    Schönfeld, Uwe; Weiming, Hu; Hofmann, Veit M; Jovanovic, Sergije; Albers, Andreas E


    Total laser energy in CO 2 stapedotomy depends on the laser settings and the amount of applications. It is unclear if the amount of total laser energy affects bone-conduction hearing thresholds and if possible effects are temporary or permanent. Alterations of bone-conduction hearing thresholds after single or multiple-shot CO 2 laser stapedotomy were analyzed between 1 and 3 weeks and 1.5-6 months after primary (n = 501) or revision surgeries (n = 153) and correlated to time, laser energy, frequency, surgical technique, and pathology encountered in revision stapedotomy. In both time periods, most patients showed a lower bone-conduction threshold in the four-tone puretone average (PTA) at frequencies of 0.5, 1, 2, and 3 kHz that further improved over time. Between 1 and 3 weeks, the improvement was significant in subgroups with cumulative energies lower 1 J and successful one-shot technique or in revisions without laser application. The remaining subgroups with higher total energies showed significant improvements between 1.5 and 6 months. At 4 and 8 kHz, significant improvements were found during 1.5-6 months after primary and revision surgery independent of the used energy. Repeated CO 2 laser applications showed no impairment in bone-conduction thresholds and can thus be considered as safe. In most patients, significant, yet unexplained, improvements in bone-conduction hearing thresholds were noticed in a time- and energy-related pattern.

  16. Clinical and histologic effects from CO2 laser treatment of keloids. (United States)

    Nicoletti, Gianfranco; De Francesco, Francesco; Mele, Carmine Michele; Cataldo, Chiara; Grella, Roberto; Brongo, Sergio; Accardo, Marina; Ferraro, Giuseppe Andrea; D'Andrea, Francesco


    Keloids and hypertrophic scars are abnormal responses to wound healing. In general, keloids exhibit a proliferative growth beyond the margins of the scar and remain persistent; while hypertrophic scars are contained to the original wound and may regress over time. In particular, keloid formation is one of the most challenging clinical problems, with increasing frequency in surgical practice. Many treatments are available such as intralesional corticosteroids, topical applications, cryotherapy, surgical excision, radiation therapy, silicone gel sheeting, pressure therapy, and laser therapy. There are no set guidelines for the treatment of keloids and the most common treatments are individualized and depended on the distribution, size, thickness, and consistency of lesions. The authors have evaluated carbon dioxide laser successfully in the treatment of keloids and the aim of this study was to determine the immediate and long-term histologic and clinical effects of keloids after carbon dioxide laser. Fifty consecutive patients (40 females, 10 males, ages 18-60 years, mean age 40 years) with moderate to severe keloids were evaluated. All the patients received regional treatments (deltoid, elbow, chin, and ear) in an outpatient setting with a high-energy pulsed CO2 laser. Significant immediate and prolonged clinical improvement in skin tone, texture, and appearance of carbon dioxide laser was examined in all patients. Dermal remodeling was observed also on histologic examination of biopsied tissue after treatment. Carbon dioxide laser appears to be effective and well tolerated for the treatment of keloids, avoiding the adverse effects and lengthy recovery time.

  17. High-pressure continuously tunable CO2 lasers and molecular laser ...

    Indian Academy of Sciences (India)


    molecular laser isotope separation) has been applied to label the laser process whereby the isotopes of uranium can ... the different approaches to harvest the product and waste material. Each of these options, to accomplish the ...

  18. Damage analysis of fiber reinforced resin matrix composites irradiated by CW laser

    International Nuclear Information System (INIS)

    Wan Hong; Hu Kaiwei; Mu Jingyang; Bai Shuxin


    In this paper, the damage modes of the carbon fiber and the glass fiber reinforced epoxy or bakelite resin matrix composites irradiated by CW laser under different power densities were analyzed, and the changes of the microstructure and the tensile strength of the composites were also researched. When the resin matrix composites were radiated at a power density more than 0.1 kW/cm 2 , the matrix would be decomposed and the tensile properties of the radiated samples were lost over 30% while the carbon fiber hardly damaged and the glass fiber melted. When the power density of the laser was raised to 1 kW/cm 2 , the matrix burned violently and the carbon fiber cloth began to split with some carbon fiber being fractured, therefore, the fracture strength of the radiated sample lost over 80%. The higher the power density of radiation was, the more serious the damage of the sample was. It was also found that the difference of the matrixes had little effect on the damage extent of the composites. The influence of the radiation density on the temperature of the radiated surface of the carbon/resin composite was numerically calculated by ANSYS finite element software and the calculation results coincided with the damage mode of the radiated composites. (authors)

  19. 267-W cw AlGaAs/GaInAs diode laser bars (United States)

    Braunstein, Juergen; Mikulla, Michael; Kiefer, Rudolf; Walther, Martin; Jandeleit, Juergen; Brandenburg, Wolfgang; Loosen, Peter; Poprawe, Reinhart; Weimann, Guenter


    High-power 980 nm-diode laser bars have been fabricated in the AlGaAs/GaInAs material system. The bars are 1 cm wide and comprise 25 broad area lasers with 200 micrometer aperture and 2 mm resonator length. Hence, the fill factor is 50%. To reduce the power density at the facet, we used an LOC structure with low modal gain, which also helps to prevent filamentation. The measured threshold current was 14 A and a record output power of 267 W cw was achieved at 333 A with an electro-optical conversion efficiency of 40%. With less thermal load, at 150 W output power the conversion efficiency was as high as 50% and the corresponding slope efficiency was 0.9 W/A. Microchannel copper heat sinks with a thermal resistance of less than 0.29 K/W were used for mounting the bars. The coolant temperature was set for all measurements to 22 degrees Celsius and the flux was 0.9 l/min. Additionally, the top electrode of the p-side down mounted bars was cooled by a second heat sink, which was pressed gently on the top electrode.

  20. Thermal infrared laser heterodyne spectroradiometry for solar occultation atmospheric CO2 measurements (United States)

    Hoffmann, Alex; Macleod, Neil A.; Huebner, Marko; Weidmann, Damien


    This technology demonstration paper reports on the development, demonstration, performance assessment, and initial data analysis of a benchtop prototype quantum cascade laser heterodyne spectroradiometer, operating within a narrow spectral window of ˜ 1 cm-1 around 953.1 cm-1 in transmission mode and coupled to a passive Sun tracker. The instrument has been specifically designed for accurate dry air total column, and potentially vertical profile, measurements of CO2. Data from over 8 months of operation in 2015 near Didcot, UK, confirm that atmospheric measurements with noise levels down to 4 times the shot noise limit can be achieved with the current instrument. Over the 8-month period, spectra with spectral resolutions of 60 MHz (0.002 cm-1) and 600 MHz (0.02 cm-1) have been acquired with median signal-to-noise ratios of 113 and 257, respectively, and a wavenumber calibration uncertainty of 0.0024 cm-1.Using the optimal estimation method and RFM as the radiative transfer forward model, prior analysis and theoretical benchmark modelling had been performed with an observation system simulator (OSS) to target an optimized spectral region of interest. The selected narrow spectral window includes both CO2 and H2O ro-vibrational transition lines to enable the measurement of dry air CO2 column from a single spectrum. The OSS and preliminary retrieval results yield roughly 8 degrees of freedom for signal (over the entire state vector) for an arbitrarily chosen a priori state with relatively high uncertainty ( ˜ 4 for CO2). Preliminary total column mixing ratios obtained are consistent with GOSAT monthly data. At a spectral resolution of 60 MHz with an acquisition time of 90 s, instrumental noise propagation yields an error of around 1.5 ppm on the dry air total column of CO2, exclusive of biases and geophysical parameters errors at this stage.

  1. Simulation and initial experiments of a high power pulsed TEA CO2 laser (United States)

    Torabi, R.; Saghafifar, H.; Koushki, A. M.; Ganjovi, A. A.


    In this paper, the output characteristics of a UV pin array pre-ionized TEA CO2 laser have been simulated and compared with the associated experimental data. In our simulation, a new theoretical model has been improved for transient behavior analysis of the discharge current pulse. The laser discharge tube was modeled by a nonlinear RLC electric circuit as a real model for electron density calculation. This model was coupled with a six-temperature model (6TM) in order to simulation dynamic emission processes of the TEA CO2 laser. The equations were solved numerically by the fourth order Runge-Kutta numerical method and some important variables such as current and voltage of the main discharge, resistance of the plasma column and electron density in the main discharge region, were calculated as functions of time. The effects of non-dissociation factor, rotational quantum number and output coupler reflectivity were also studied theoretically. The experimental and simulation results are in good agreement.

  2. Early Regenerative Modifications of Human Postmenopausal Atrophic Vaginal Mucosa Following Fractional CO2 Laser Treatment

    Directory of Open Access Journals (Sweden)

    Stefano Salvatore


    Full Text Available BACKGROUND: Postmenopausal women experience undesired symptoms that adversely affect their quality of life. In the recent years, a specific 12 - week fractional CO2 laser treatment has been introduced, with highly significant relief of symptoms. AIM: The aim of this paper is the identification of the early modifications of structural components of atrophic vaginal mucosa induced by laser irradiation, which is responsible for the restorative processes. MATERIAL AND METHODS: We investigated by microscopical, ultrastructural and biochemical methods the modifications of the structural components of postmenopausal atrophic vaginal mucosa tissues after 1 hour following a single fractional laser CO2 application. RESULTS: In one hour, the mucosal epithelium thickens, with the maturation of epithelial cells and desquamation at the epithelial surface. In the connective tissue, new papillae indenting the epithelium with newly formed vessels penetrating them, new thin fibrils of collagen III are also formed in a renewed turnover of components due to the increase of metalloproteinase - 2. Specific features of fibroblasts support stimulation of their activity responsible of the renewal of the extracellular matrix, with an increase of mechanical support as connective tissue and stimulation of growth and maturation to epithelium thanks to new vessels and related factors delivered. CONCLUSION: We found the activation of regenerative mechanisms expressed both in the connective tissue - with the formation of new vessels, new papillae, and new collagen - and in the epithelium with the associated thickening and desquamation of cells at the mucosal surface.

  3. Applying the CO2 laser collective Thomson scattering results from JT-60U to other machines (United States)

    Richards, R. K.; Hutchinson, D. P.; Bennett, C. A.; Kondoh, T.; Miura, Y.; Lee, S.


    A collective Thomson scattering (CTS) system based on a pulsed CO2 laser is being developed to demonstrate the feasibility of alpha-particle diagnostics. Tests on this system are being conducted on the JT-60U tokamak. The system consists of a pulsed laser (15 J in 1:s at 10.6:m) and a wide band (˜8 GHz) heterodyne receiver with a quantum-well infrared photodetector [Liu et al., IEEE Electron Device Lett. 16, 253 (1995)]. Stray light is reduced by a notch filter containing hot CO2 gas. The heterodyne receiver is absolutely calibrated using a large area blackbody radiation source [Bennett et al., Appl. Opt. 27, 3324 (1988)]. Results from the tests on JT-60U indicate a larger than expected noise background, especially for the lower velocity measurements determined by the smaller frequency shifts from the laser line. These results are used to estimate the signal-to-noise ratio that would be expected for a CTS diagnostic installed on other devices; ITER ("the way" in Latin), Joint European Torus-Enhanced Performance JET-EP, and axially symmetric divertor experiment (ASDEX). Calculations and possible system improvements are presented.

  4. Quantitative measurement of carbon isotopic composition in CO2gas reservoir by Micro-Laser Raman spectroscopy. (United States)

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


    The use of Micro-Laser Raman spectroscopy technology for quantitatively determining gas carbon isotope composition is presented. In this study, 12 CO 2 and 13 CO 2 were mixed with N 2 at various molar fraction ratios to obtain Raman quantification factors (F 12CO2 and F 13CO2 ), which provide a theoretical basis for calculating the δ 13 C value. And the corresponding values were 0.523 (0CO2 /C N2 <2) and 1.11998 (0CO2 /C N2 <1.5) respectively. It has shown that the representative Raman peak area can be used for the determination of δ 13 C values within the relative errors range of 0.076% to 1.154% in 13 CO 2 / 12 CO 2 binary mixtures when F 12CO2 /F 13CO2 is 0.466972625. In addition, measurement of δ 13 C values by Micro-Laser Raman analysis were carried out on natural CO 2 gas from Shengli Oil-field at room temperature under different pressures. The δ 13 C values obtained by Micro-Laser Raman spectroscopy technology and Isotope Ratio Mass Spectrometry (IRMS) technology are in good agreement with each other, and the relative errors range of δ 13 C values is 1.232%-6.964%. This research provides a fundamental analysis tool for determining gas carbon isotope composition (δ 13 C values) quantitatively by using Micro-Laser Raman spectroscopy. Experiment of results demonstrates that this method has the potential for obtaining δ 13 C values in natural CO 2 gas reservoirs. Copyright © 2018. Published by Elsevier B.V.

  5. Comparação das técnicas de turbinectomia com laser de CO2 e laser a diodo Comparison of turbinectomy techniques with CO2 laser and diode laser

    Directory of Open Access Journals (Sweden)

    Pedro Paulo Vivacqua da Cunha Cintra


    Full Text Available Avaliação das técnicas de turbinectomia com laser de CO2 e da redução volumétrica das conchas nasais inferiores de maneira intersticial com o laser de diodo, em pacientes com hipertrofia do parênquima nasal. FORMA DE ESTUDO: Coorte Longitudinal. MATERIAL E MÉTODO: Foram avaliados 60 pacientes submetidos a estes procedimentos com um período de seguimento de 6 meses de acordo com protocolo onde foram avaliados os parâmetros de sangramento, dor e avaliação subjetiva da obstrução nasal pré e pós-operatória. RESULTADOS: As técnicas demonstraram um baixo índice de sangramento não tendo sido necessário o tampão nasal em nenhum dos casos e alto grau de satisfação dos pacientes no quesito obstrução nasal quando comparados os valores iniciais com os resultados aos seis meses. CONCLUSÃO: Os procedimentos nas conchas nasais devem visar a melhora do quadro obstrutivo, e satisfação do paciente com pouco desconforto tanto intra como pós-operatório. As técnicas de redução volumétrica com o laser de diodo e de CO2 mostram-se no presente estudo eficazes em 6 meses.We describe an evaluation of the techniques aiming to reduce the bulk of inferior turbinates with the diode laser and the CO2 laser, as well as a comparison between the techniques. STUDY DESIGN: Longitudinal Cohort. MATERIAL AND METHOD: Sixty patients with turbinate hypertrophy were submitted to the submucous diode laser reduction and CO2 with a follow up period of 6 months following a established protocol concerning pain, bleeding and subjective evaluation of the nasal obstruction preoperatively and postoperatively. RESULTS: The procedures showed a low level of bleeding and no packing was necessary in all patients. We observed that the patients were very pleased concerning the nasal obstruction postoperatively. CONCLUSION: The primary goal of the inferior turbinectomy is to reduce the patient complain of nasal obstruction with less discomfort, morbidity and

  6. CO2 laser myringotomy with a hand-held otoscope and fiber optic delivery system: animal experimentation and preclinical trials (United States)

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


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

  7. Fabrication quality analysis of a fiber optic refractive index sensor created by CO2 laser machining. (United States)

    Chen, Chien-Hsing; Yeh, Bo-Kuan; Tang, Jaw-Luen; Wu, Wei-Te


    This study investigates the CO2 laser-stripped partial cladding of silica-based optic fibers with a core diameter of 400 μm, which enables them to sense the refractive index of the surrounding environment. However, inappropriate treatments during the machining process can generate a number of defects in the optic fiber sensors. Therefore, the quality of optic fiber sensors fabricated using CO2 laser machining must be analyzed. The results show that analysis of the fiber core size after machining can provide preliminary defect detection, and qualitative analysis of the optical transmission defects can be used to identify imperfections that are difficult to observe through size analysis. To more precisely and quantitatively detect fabrication defects, we included a tensile test and numerical aperture measurements in this study. After a series of quality inspections, we proposed improvements to the existing CO2 laser machining parameters, namely, a vertical scanning pathway, 4 W of power, and a feed rate of 9.45 cm/s. Using these improved parameters, we created optical fiber sensors with a core diameter of approximately 400 μm, no obvious optical transmission defects, a numerical aperture of 0.52 ± 0.019, a 0.886 Weibull modulus, and a 1.186 Weibull-shaped parameter. Finally, we used the optical fiber sensor fabricated using the improved parameters to measure the refractive indices of various solutions. The results show that a refractive-index resolution of 1.8 × 10(-4) RIU (linear fitting R2 = 0.954) was achieved for sucrose solutions with refractive indices ranging between 1.333 and 1.383. We also adopted the particle plasmon resonance sensing scheme using the fabricated optical fibers. The results provided additional information, specifically, a superior sensor resolution of 5.73 × 10(-5) RIU, and greater linearity at R2 = 0.999.

  8. Innocuous skin cooling modulates perception and neurophysiological correlates of brief CO2 laser stimuli in humans. (United States)

    Nahra, Hicham; Plaghki, Léon


    The present study examined the influence of innocuous skin cooling on the perception and neurophysiological correlates of brief noxious CO2 laser stimuli. In nine normal subjects, brief CO2 laser pulses of four different intensities (duration 50 ms; diameter 5 mm; intensity range 5.8-10.6 mJ/mm2) were delivered at random every 5-10 s on the dorsum of the hand. Innocuous skin cooling was performed by a thermode (20 degrees C; 3x3 cm) with a central hole for the laser test stimuli. Quality and intensity (VAS) of perceptions, reaction times and laser evoked potentials (LEPs) were examined. Signal detection theory analysis was performed to evaluate discrimination performance and decision criterion. During innocuous skin cooling, detection threshold increased from 4.8+/-1.81 to 8.2+/-1.05 mJ/mm2 and pain threshold from 8.7+/-1.53 to 13.5+/-1.57 mJ/mm2. proportion of detected stimuli decreased from 87% to 48% and pain reports from 42% to 10%. The well localized 'pricking' sensation mediated by Adelta-nociceptors almost vanished. The intensity of sensations (VAS scores) was considerably reduced. Sensory discriminative performance was significantly depressed but decision criterion remained unchanged. Reaction times were delayed. The late-LEPs, correlates of Adelta-nociceptor activations, were also significantly depressed while the ultra-late LEPs, correlates of C-nociceptors, were not affected. Taken together, these results strongly suggest that innocuous skin cooling interfered with the sensory processing of laser heat stimuli and more prominently with those related to Adelta-nociceptive input.

  9. Measurement of CO2 laser small angle Thomson scattering on a magnetically confined plasma (United States)

    Richards, R. K.; Hutchinson, D. P.; Bennett, C. A.; Hunter, H. T.; Ma, C. H.


    We report the first successful small-angle (less than 1°) Thomson scattering measurement of 10 μm radiation from a magnetically confined toroidal plasma. This represents a proof-of-principle demonstration of a new diagnostic technique for confined deuterium-tritium fusion-product alpha particles in future fusion reactors. This result was achieved by detecting scattered CO2 laser light from the plasma of the ATF torsatron at an angle of 0.86° using a novel heterodyne receiver scheme. A predicted resonance in the scattered power as a function of plasma electron density is clearly resolved in the measurements.

  10. CO2-laser ablation of Bi-Sr-Ca-Cu oxide by millisecond pulse lengths (United States)

    Meskoob, M.; Honda, T.; Safari, A.; Wachtman, J. B.; Danforth, S.; Wilkens, B. J.


    We have achieved ablation of Bi-Sr-Ca-Cu oxide from single targets of superconducting pellets by CO2-laser pulses of l ms length to grow superconducting thin films. Upon annealing, the 6000-Å thin films have a Tc (onset) of 90 K and zero resistance at 78 K. X-ray diffraction patterns indicate the growth of single-phase thin films. This technique allows growth of uniform single-phase superconducting thin films of lateral area greater than 1 cm2.

  11. Flame temperature trends in reacting vanadium and tungsten ethoxide fluid sprays during CO2-laser pyrolysis

    CSIR Research Space (South Africa)

    Mwakikunga, BW


    Full Text Available [z] in Eq. 6, shortened for ProductLog[z], is a Mathematica command which gives the solution of w in the expression z = w ew. The final ?equilibrium? temperature of molecules that are entrained into a CO2 laser beam found either by letting t as can...) and was thus compared to the black body spectrum of known emissivity, (assumed to be unity) and known temperature 900 K. In order to calculate ?equilibrium temperature? at a particular point in the flame, either spectral emissivity of the flame...

  12. Interferometria com laser de CO2 no TC-1 da UNICAMP


    Roosevelt Droppa Junior


    Resumo: Foram executadas, no toroide compacto TC-1 da UNICAMP, um thetapinch que permite a geração e o confinamento magnético de plasmas, tres técnicas de medição da densidade eletrônica integrada do plasma baseadas em interferometria, utilizando-se como fonte de radiação eletromagnética um laser de CO2( l = 10.6 mm). Na primeira delas, utiliza-se apenas um detetor de infravermelho para contagem de franjas de interferência. O número de franjas deslocadas quando ocorre a implosão do plasma ...

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

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


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

  14. Studies on the transmission of viral disease via the CO2 laser plume and ejecta. (United States)

    Wisniewski, P M; Warhol, M J; Rando, R F; Sedlacek, T V; Kemp, J E; Fisher, J C


    While recent reports have noted the presence of viral DNA sequences in the laser plume, no significant effort has been made to study transmission of the virus in vivo via airborne laser debris. Studies were undertaken to identify potential hazards to operating room occupants in gynecologic laser surgery. ACO2 laser in the continuous wave mode using a power density of 666 W/cm2 was fired through a 5-cm metal cylinder at virus-infected tissues. Airborne particulate debris, 100-200 microns, was removed from the cylinder's inner surfaces. In one instance, deposition of the debris was found on the surgeon's eyeglasses 1 m from the site of impact despite the use of a smoke evacuator. The first set of studies involved confirmed human papillomavirus (HPV) lesions of the human female lower genital tract. Specimens were collected for electron microscopy and Southern Blot viral hybridization. Additional cervical electron microscopy specimens were recovered from the speculum during pulsed CO2 laser treatment at 13 W average power during conization. Electron microscopy of the vulvar debris revealed only anucleate keratinized squamous epithelial cells. Cervical specimens demonstrated similar cells with nearly instantaneous vaporization of intracellular water and apparent condensation of cellular carbon. HPV Southern Blot testing revealed insufficient quantities of DNA for that technique. The second set of studies involved bovine papillomavirus lesions from dairy cattle. The debris was transmitted to susceptible animals. The bovine studies failed to demonstrate the transmission of disease in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)

  15. Rapid and low-cost fabrication of polystyrene-based molds for PDMS microfluidic devices using a CO2 laser

    KAUST Repository

    Li, Huawei


    In this article, we described a rapid and low-cost method to fabricate polystyrene molds for PDMS microfluidic devices using a CO2 laser system. It takes only several minutes to fabricate the polystyrene mold with bump pattern on top of it using a CO2 laser system. The bump pattern can be easily transferred to PDMS and fabricate microchannles as deep as 3μm on PDMS. © (2012) Trans Tech Publications, Switzerland.

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

    Directory of Open Access Journals (Sweden)

    Thayanne Monteiro RAMOS-OLIVEIRA


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

  17. An Improved Method of Mitigating Laser Induced Surface Damage Growth in Fused Silica Using a Rastered, Pulsed CO2 Laser

    Energy Technology Data Exchange (ETDEWEB)

    Bass, I L; Guss, G M; Nostrand, M J; Wegner, P L


    A new method of mitigating (arresting) the growth of large (>200 m diameter and depth) laser induced surface damage on fused silica has been developed that successfully addresses several issues encountered with our previously-reported large site mitigation technique. As in the previous work, a tightly-focused 10.6 {micro}m CO{sub 2} laser spot is scanned over the damage site by galvanometer steering mirrors. In contrast to the previous work, the laser is pulsed instead of CW, with the pulse length and repetition frequency chosen to allow substantial cooling between pulses. This cooling has the important effect of reducing the heat-affected zone capable of supporting thermo-capillary flow from scale lengths on the order of the overall scan pattern to scale lengths on the order of the focused laser spot, thus preventing the formation of a raised rim around the final mitigation site and its consequent down-stream intensification. Other advantages of the new method include lower residual stresses, and improved damage threshold associated with reduced amounts of redeposited material. The raster patterns can be designed to produce specific shapes of the mitigation pit including cones and pyramids. Details of the new technique and its comparison with the previous technique will be presented.

  18. Short-pulse CO2-laser damage studies of NaCl and KCl windows

    International Nuclear Information System (INIS)

    Newnam, B.E.; Nowak, A.V.; Gill, D.H.


    The damage resistance of bare surfaces and the bulk interior of NaCl and KCl windows was measured with a short-pulse CO 2 laser at 10.6 μm. Parametric studies with 1.7-ns pulses indicated that adsorbed water was probably the limiting agent on surface thresholds in agreement with previous studies at long pulsewidths. Rear-surface thresholds up to 7 J/cm 2 were measured for polished NaCl windows, whereas KCl surfaces damaged at approximately 60% of this level. The breakdown electric-field thresholds of exit surfaces were only 50% of the value of the bulk materials. The pulsewidth dependence of surface damage from 1 to 65 ns, in terms of incident laser fluence, increased as t/sup 1/3/

  19. Dissociation of NH3 and NH2D by high power CO2 laser radiation

    International Nuclear Information System (INIS)

    Jacobs, R.R.


    Multiquantum dissociation of polyatomics using intense CO 2 lasers resulting in isotopic enrichment has been demonstrated for several molecules. In this presentation, the possibility of selective dissociation of NH 3 and NH 2 D by high power laser radiation at 10 μm will be considered. Relevant work performed at the Lawrence Livermore Laboratory and elsewhere will be summarized. In this review, attention will be given to four distinct mechanisms that can play varying degrees of importance in such investigations. Discussion will deal with the usefulness of two-resonant-frequency molecular excitation, the role of buffer gases, and the need to monitor the yields into the ground and excited electronic states of the dissociated fragments

  20. Pulsed CO2 laser tissue ablation: measurement of the ablation rate. (United States)

    Walsh, J T; Deutsch, T F


    Ablation of guinea pig skin using a CO2 laser emitting 2-mu sec-long pulses has been quantified by measuring the mass of tissue removed as a function of incident fluence per pulse. The mass-loss curves show three distinct regimes in which water evaporation, explosive tissue removal, and laser-induced plasma formation dominate. The data are fit to two models that predict that the mass removed depends either linearly or logarithmically on fluence. Although the data are best fit by a linear dependence upon fluence, plasma formation at high fluences prohibited obtaining data over a wide enough fluence range to differentiate unambiguously between the two models. Ablation efficiency, ablation thresholds, and the optical penetration depth at 10.6 micron were obtained from the measurements.

  1. Angle-dependent light emission from aligned multiwalled carbon nanotubes under CO2 laser irradiation

    International Nuclear Information System (INIS)

    Zhang, Y; Gong, T; Liu, W J; Wei, J Q; Zhang, X F; Wang, K L; Zhong, M L; Wu, D H


    This paper reports the light emission from aligned multiwalled carbon nanotubes (MWNTs) under continuous wave CO 2 laser (λ = 10.6 μm) irradiation. Results indicate that the light emission is dependent on the angle θ between the laser incident direction and the nanotube axis. The relative intensity of the light emission at certain wavelengths shows a Lorentzian feature when θ varies from 0 0 to 90 0 . The Lorentzian fitting curve displays a distinct tendency between shorter (λ 700 nm). A minimum intensity was observed at θ m close to 67 0 under shorter wavelength, whereas a maximum intensity was shown at θ m of about 60 0 at longer wavelength. These results show the anisotropic property of aligned MWNTs

  2. Single-frequency TEA CO2 laser with a bleaching spectral intracavity filter (United States)

    Sorochenko, V. R.


    The regime of single-frequency operation is realised in a TEA CO2 laser with a spectral filter inside the cavity (a cell filled with SF6) on P(12)-P(24) lines of the 10P band. The minimal scatter of the peak powers of the laser pulses in a series of ‘shots’ and the maximal ratio of the output energies in the single-frequency and free running regimes (greater than 0.84) are obtained on the P(16) line at an optimal SF6 pressure in the cell. Experimental results qualitatively agree with the absorption spectrum of SF6 calculated from the SPECTRA information-analytical system. It is shown that the high ratio of energies in two regimes is achived due to gas bleaching in the cell.

  3. Assessment of radicular dentin permeability after irradiation with CO2 laser and endodontic irrigation treatments with thermal imaging (United States)

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


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

  4. Does the CO2 laser reduce bond strength in different types of ceramic brackets?

    Directory of Open Access Journals (Sweden)

    Fábio Lourenço Romano

    Full Text Available ABSTRACT OBJECTIVE: The aim of this study was to assess in vitro the influence of the CO2 laser and of the type of ceramic bracket on the shear bond strength (SBS to enamel. METHODS: A total of 60 enamel test surfaces were obtained from bovine incisors and randomly assigned to two groups, according to the ceramic bracket used: Allure (A; Transcend (T. Each group was divided into 2 subgroups (n = 15: L, laser (10W, 3s; C, no laser, or control. Twenty-four hours after the bonding protocol using Transbond XT, SBS was tested at a crosshead speed of 0.5 mm/min in a universal testing machine. After debonding, the Adhesive Remnant Index (ARI was evaluated at 10 x magnification and compared among the groups. Data were analyzed by one-way ANOVA, Tukey’s, Mann-Whitney’s and Kruskal-Wallis tests (α = 0.05. RESULTS: Mean SBS in MPa were: AL = 0.88 ± 0.84; AC = 12.22 ± 3.45; TL = 12.10 ± 5.11; TC = 17.71 ± 6.16. ARI analysis showed that 73% of the specimens presented the entire adhesive remaining on the tooth surfaces (score 3. TC group presented significantly higher SBS than the other groups. The lased specimens showed significantly lower bond strength than the non-lased groups for both tested brackets. CONCLUSION: CO2 laser irradiation decreased SBS values of the polycrystalline ceramic brackets, mainly Allure.

  5. High Efficiency Mask Based Laser Materials Processing with TEA-CO2 - and Excimer Laser

    DEFF Research Database (Denmark)

    Bastue, Jens; Olsen, Flemmming Ove


    In general, mask based laser materials processing techniques suffer from a very low energy efficiency. We have developed a simple device called an energy enhancer, which is capable of increasing the energy efficiency of typical mask based laser materials processing systems. A short review...

  6. Lower energy and pulse stacking. A safer alternative for skin tightening using fractional CO2 laser. (United States)

    Motta, Marcos Matias; Stelini, Rafael Fantelli; Calderoni, Davi Reis; Gilioli, Rovilson; Kharmandayan, Paulo


    To evaluate the effect of different energies and stacking in skin shrinkage. Three decreasing settings of a fractional CO2 laser were applied to the abdomen of Twenty five Wistar rats divided into three groups. Group I (n=5) was histologically evaluated for microthermal zones dimensions. Groups II and III (n=10 each) were macroscopic evaluated with freeware ImageJ for area contraction immediately and after 30 and 60 days. No statistical significance was found within microthermal zone histological dimensions (Group I) in all settings studied. (Ablation depth: 76.90 to 97.18µm; Coagulation depth: 186.01 to 219.84 µm). In Group II, macroscopic evaluation showed that all settings cause significant immediate skin contraction. The highest setting cause significant more intense tightening effect initially, contracting skin area from 258.65 to 179.09 mm2. The same pattern was observed in Group III. At 30 and 60 days, the lowest setting significantly sustained contraction. Lower fractional CO2 laser energies associated to pulse stacking could cause consistent and long lasting tissue contraction in rats.

  7. The treatment of oral leukoplakia with the CO2 laser: A retrospective study of 65 patients. (United States)

    Mogedas-Vegara, Alfonso; Hueto-Madrid, Juan-Antonio; Chimenos-Küstner, Eduardo; Bescós-Atín, Coro


    The use of CO2 laser has become a routine procedure for the treatment of oral leukoplakia. In this retrospective study, we evaluated 65 patients with oral leukoplakia treated with CO2 laser vaporization. The main location was the tongue (n = 21/65, 32.3%). The initial biopsy showed mild/moderate dysplasia in almost half the patients (n = 29, 44.6%) and hyperplasia without dysplasia in around a third of the patients (n = 21, 32.3%). The recurrence and malignant transformation rates were 33.8% (n = 22) and 15.4% (n = 10), respectively. The follow-up mean (standard deviation) was 15.0 (10.6) months. The procedure-related complications rate was 7.7% (n = 5). The Kaplan-Meier curves for time to recurrence showed differences only for gingiva lesions compared to tongue lesions (log rank, p = 0.032). Malignant leukoplakia transformation is independent of treatment, although it seems advisable to treat leukoplakia with or without dysplasia. Copyright © 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  8. Study of electron kinetics in nitrogen plasma induced by CO2 laser radiation (United States)

    Nassef, O. Aied; Gamal, Yosr E. E.-D.


    In the present work, a numerical modeling is performed to study the electron kinetics in nitrogen plasma induced by CO2 laser radiation operating at wavelength 9.621 μm, and pulse duration of 60 ns corresponding to the measurements carried out by Camacho et al. (J Phys B At Mol Opt Phys 40:4573, 2007). In this experiment, the breakdown threshold intensity is determined for molecular nitrogen over a pressure range 301-760 torr. A previously developed electron cascade model (Evans and Gamal in J Phys D Appl Phys 13:1447, 1980) is modified and applied. This model is based on numerical solution of a time-dependent energy equation and a set of rate equations that describe the time variation of the formed excited states population. The effect of breakdown mechanism is decided through the calculations of the threshold intensity as a function of gas pressure considering the various physical processes that might take place during the interaction. The individual effect of each loss process on the electron energy distribution function and its parameters is studied. This study is performed at the lowest and highest values of the experimentally tested gas pressure range namely; 301 and 760 torr. The obtained results clarified the exact contribution of each loss process to the breakdown of nitrogen induced by CO2 laser radiation.

  9. Estudo comparativo entre blefaropeeling e laser fracionado de CO2 no tratamento do rejuvenescimento periorbital

    Directory of Open Access Journals (Sweden)

    Elisangela dos Santos Boeno


    Full Text Available Introdução: A queixa de rugas e flacidez na região periocular é freqüente.O blefaropeelingutilizando a fórmula de Baker-Gordon e a aplicação de laser fracionado ablativo de CO2 fracionado são consideradas opções efetivas para o tratamento dessa região. Objetivo: Comparar as técnicas, a recuperação e os resultados finais das duas modalidades terapêuticas. Material e Métodos: Estudo comparativo de hemi-faces em pacientes com dermatocálase e rítides moderadas. Realizou-se no lado direito blefaropeeling e, no esquerdo, laser fracionado de CO2, cujos resultados foram avaliados por fotografia, medidas do sulco palpebral superior e melhora clínica. Resultados: Foram incluídas 11 pacientes no protocolo.Verificou-se melhora clínica efotográfica com ambos os métodos. O tempo de recuperação foi maior com o peeling de fenol. As medidas do sulco palpebral superior não mostraram diferenças significativas. Conclusões: Ambas as modalidades terapêuticas são efetivas no tratamento do envelhecimento periorbital. O processo de recuperação o blefaropeeling foi mais demorado. Clinicamente a melhora da flacidez palpebral foi superior com o blefaropeeling.

  10. INTERACTION OF LASER RADIATION WITH MATTER: Influence of a target on operation of a pulsed CO2 laser emitting microsecond pulses (United States)

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


    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.

  11. Experimental study on three-longitudinal-mode CW laser output of LD-pumped Nd:YAG thin disk (United States)

    He, Dongbing; Zhao, Changming; Guan, Zhe; Li, Jinhua; Zhang, Haiyang


    The increase of the numbers of laser channel is beneficial to the improvement of laser communication capacity, and a three-longitudinal-mode Nd:YAG laser with a central wavelength of 1.06 μm is studied. The three-longitudinal-mode continuous-wave(CW) laser output is obtained in 808nm LD-pumped 2.4mm Nd: YAG thin disk with a slope efficiency of 11.65% at 20°, the output power of the CW laser is 11.9mW when the power of the pumping is 365mW, and the frequency spacing is 35.4GHz.The maximum output power of 60.3mW is obtained under the 801mW pumped power. The longitudinal mode gain competition is verified in the experiment and the three-longitudinal-mode laser can maintain a stable output when the pumped power reaches 667mW. With the pump power increases, the frequency of laser output power increases, also accompanied by the phenomenon of frequency drift.

  12. Fabrication of rectangular cross-sectional microchannels on PMMA with a CO2 laser and underwater fabricated copper mask (United States)

    Prakash, Shashi; Kumar, Subrata


    CO2 lasers are commonly used for fabricating polymer based microfluidic devices. Despite several key advantages like low cost, time effectiveness, easy to operate and no requirement of clean room facility, CO2 lasers suffer from few disadvantages like thermal bulging, improper dimensional control, difficulty to produce microchannels of other than Gaussian cross sectional shapes and inclined surface walls. Many microfluidic devices require square or rectangular cross-sections which are difficult to produce using normal CO2 laser procedures. In this work, a thin copper sheet of 40 μm was used as a mask above the PMMA (Polymethyl-methacrylate) substrate while fabricating the microchannels utilizing the raster scanning feature of the CO2 lasers. Microchannels with different width dimensions were fabricated utilizing a CO2 laser in with mask and without-mask conditions. A comparison of both the fabricating process has been made. It was found that microchannels with U shape cross section and rectangular cross-section can efficiently be produced using the with mask technique. In addition to this, this technique can provide perfect dimensional control and better surface quality of the microchannel walls. Such a microchannel fabrication process do not require any post-processing. The fabrication of mask using a nanosecond fiber laser has been discussed in details. An underwater laser fabrication method was adopted to overcome heat related defects in mask preparation. Overall, the technique was found to be easy to adopt and significant improvements were observed in microchannel fabrication.

  13. Plasma column development in the CO2 laser-heated solenoid

    International Nuclear Information System (INIS)

    Tighe, W.; Offenberger, A.A.; Capjack, C.E.


    Axial and radial plasma dynamics in the CO 2 laser-heated solenoid have been studied experimentally and numerically. The axial behavior is found to be well described by a self-regulated bleaching wave model. The radial expansion is found to be strongly dependent on the focusing ratio of the input laser beam. With a fast focus ( f/5), the early radial expansion rate is twice that found with a slower focusing arrangement ( f/15). The faster focusing ratio also results in a significantly wider plasma column. On the other hand, no significant dependence of f/number on the axial propagation was found. A finite ionization time and the rapid formation of a density minimum on axis are observed and verify earlier experimental results. Detailed comparisons are made with a 2-D magnetohydrodynamic (MHD) and laser propagation code. The axial and radial plasma behavior and, in particular, the dependence of the radial behavior on the focal ratio of the laser are reasonably well supported by the simulation results. Computational results are also in good agreement with experimental measurements of temperature and density using stimulated scattering (Brillouin, Raman) and interferometry diagnostic techniques

  14. Fabrication and simulation of glass micromachining using CO2 laser processing with PDMS protection (United States)

    Chung, C. K.; Lin, S. L.; Wang, H. Y.; Tan, T. K.; Tu, K. Z.; Lung, H. F.


    Traditional glass micromachining using laser processing in air would produce many kinds of defects, such as bulges, debris, micro-cracks and scorches. In this article, a poly-dimethylsiloxane (PDMS) protection processing has been presented to reduce the temperature gradient and heat-affected zone (HAZ) to achieve crack-free Pyrex glass machining. A good quality of etched surface which is a clear and much-reduced bulge without crack and scorch is achieved using CO2 laser micromachining at 150 μm thick PDMS protection layer and the laser powers of 10-15 W and scanning speeds of 228-342 mm/s for five passes. The PDMS cover layer benefits feature size and bulge height reduction. The alpha-step measured profile shows that the much reduced bulge height around the rims of channel was about 1.2 μm at 150 μm thick PDMS about 13 times smaller than that in air. The ANSYS software was used to analyze the temperature distribution and thermal stress field of glass micromachining in air without and with PDMS cover layer. The smaller temperature gradient observed in PDMS protection processing has the smaller HAZ and diminishes the crack formation during the laser processing.

  15. Laser Radiation CO2 Effects in Cement Paste at Different Hydration Stages after Preparation

    Directory of Open Access Journals (Sweden)

    Moreno-Virgen M.R.


    Full Text Available In this work the changes occurring in cement pastes irradiated by 10.6µm CO2 laser at diff erent stages of hydration after preparation are presented. Raman spectroscopy, X-ray diffraction and Scanning Electronic Microscopy (SEM techniques were used to observe molecular structural changes. Intensity of cement paste Raman peaks after laser irradiation was monitored in samples irradiated 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11 days after their preparation. Applied laser power changed Raman peaks intensity at 187.5cm-1, 563cm-1, 695cm-1, 750cm-1, 897cm-1, 1042cm-1 and 1159cm-1 that correspond to compounds already present in cement pastes. X-ray diffraction, SEM images and changes in the Raman peaks confirm the recrystalization of cement paste compounds into new phases (alite and belite after irradiation. The produced changes show a clear dependence on the applied laser power density and age of samples.

  16. Initiation of long, free-standing z discharges by CO2 laser gas heating (United States)

    Niemann, C.; Tauschwitz, A.; Penache, D.; Neff, S.; Knobloch, R.; Birkner, R.; Presura, R.; Hoffmann, D. H. H.; Yu, S. S.; Sharp, W. M.


    High current discharge channels can neutralize both current and space charge of very intense ion beams. Therefore, they are considered an interesting solution for final focus and beam transport in a heavy ion beam fusion reactor. At the Gesellschaft für Schwerionenforschung accelerator facility, 50 cm long, free-standing discharge channels were created in a 60 cm diameter metallic chamber. Discharges with currents of 45 kA in 2 to 25 mbar ammonia (NH3) gas are initiated by a CO2 laser pulse along the channel axis before the capacitor bank is triggered. Resonant absorption of the laser, tuned to the v2 vibration of the ammonia molecule, causes strong gas heating. Subsequent expansion and rarefaction of the gas prepare the conditions for a stable discharge to fulfill the requirements for ion beam transport. The influence of an electric prepulse on the high current discharge was investigated. This article describes the laser-gas interaction and the discharge initiation mechanism. We found that channels are magnetohydrodynamic stable up to currents of 45 kA, measured by fast shutter and streak imaging techniques. The rarefaction of the laser heated gas is studied by means of a one-dimensional Lagrangian fluid code (CYCLOPS) and is identified as the dominant initiation mechanism of the discharge.

  17. CW laser-induced photothermal conversion and shape transformation of gold nanodogbones in hydrated chitosan films

    Energy Technology Data Exchange (ETDEWEB)

    Ratto, Fulvio, E-mail:; Matteini, Paolo [National Research Council of Italy, Institute of Applied Physics (Italy); Cini, Alberto [University of Florence, Department of Physics and Astronomy (Italy); Centi, Sonia [University of Florence, Department of Clinical Physiopathology (Italy); Rossi, Francesca [National Research Council of Italy, Institute of Applied Physics (Italy); Fusi, Franco [University of Florence, Department of Clinical Physiopathology (Italy); Pini, Roberto [National Research Council of Italy, Institute of Applied Physics (Italy)


    We investigate the photothermal conversion and transformation of gold nanoparticles with an initial dogbone shape after dispersion in hydrated chitosan films, which is a representative model of biological tissue, and excitation by a CW diode laser for 1 min. Gold nanodogbones are observed to undergo a distinct modification above a sharp threshold of {approx}11 W cm{sup -2} and 110 Degree-Sign C. Surprisingly, the very same modification is achieved up to at least 36 W cm{sup -2} and 250 Degree-Sign C. We use an analytical model derived from Gans theory to associate the change in color of the films with the change in shape statistics of these gold nanoparticles. This model proves both convenient and dependable. We interpret the photothermal transformation as a rearrangement of particles with a dogbone shape and an aspect ratio of 4.1 into rods with an aspect ratio of 2.5, where material from the end lobes of the dogbones may relocate to the waists of the rods. In turn, additional transitions to stable gold nanospheres may exhibit fairly slower kinetics.

  18. CW and Q-switched performance of a diode end-pumped Yb:YAG laser. Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    Bibeau, C.; Beach, R.; Ebbers, C.; Emanuel, M.; Skidmore, J.


    Using an end-pumped technology developed at LLNL we have demonstrated a Yb:YAG laser capable of delivering up to 434 W of CW power and 226 W of Q-switched power. In addition, we have frequency doubled the output to 515 nm using a dual crystal scheme to produce 76 W at 10 kHz in a 30 ns pulse length.

  19. Tunable Seed Lasers for Laser Remote Sensing of CO2 and O2, Phase I (United States)

    National Aeronautics and Space Administration — Vescent Photonics propose to develop a chip-sized narrow linewidth ( 10 nm's) diode laser that will be suitable for a wide variety of NASA remote sensing missions....

  20. $CO_{2}$ laser ion source Comparison between mode-locked and free- running laser beams

    CERN Document Server

    Lisi, N; Scrivens, R


    The production of highly charged ions in a CO/sub 2/ laser-generated plasma is compared for different laser pulse-time structures. The work was performed at the CERN Laser Ion Source, which has the aim of developing a high current, high charge-state ion source for the Large Hadron Collider (LHC). When an intense laser pulse is focused onto a high-Z metal target, the ions expanding in the plasma plume are suitable for extraction from the plasma and matching into a synchrotron. For the first time, a comparison is made between free- running pulses with randomly fluctuating intensity, and mode-locked pulse trains with a reproducible structure and the same energy. Despite the lower power density with respect to the mode-locked pulse train, the free-running pulse provides higher charge states and higher yield. (10 refs).

  1. Results of CO2 Laser-assisted Deep Sclerectomy as Compared With Conventional Deep Sclerectomy. (United States)

    Greifner, Gabriel; Roy, Sylvain; Mermoud, André


    To evaluate the efficacy of CO2 laser-assisted sclerectomy surgery (CLASS) compared with classic nonpenetrating deep sclerectomy (NPDS) with implant in medically uncontrolled glaucoma patients. Patients who underwent primary filtration surgery with CO2 laser system at the time interval between July 2010 and April 2011 were identified, their medical files were reviewed, and their results were compared with matched control group who underwent classic NPDS with intrascleral implant at the same time period. Intraocular pressure (IOP) was measured at baseline, 1 week, and 3, 6, 12, 18, and 24 months, respectively. Main outcome measures were: IOP, use of supplemental medical therapy, and failure (5 mm Hg>IOP>18 mm Hg, reoperation for glaucoma, or loss of light perception). A total of 58 patients were reviewed, including 27 in the CLASS group and 31 in the NPDS group. For the CLASS group the follow-up (mean±SD) was 20.7±6.8 months, the mean preoperative IOP was 23.3±8.2 mm Hg (range, 10 to 38 mm Hg), and the mean number of antiglaucoma medication before surgery was 3.0±1.0 (range, 1 to 4). At final follow-up visits, the mean IOP was 11.7±3.1 mm Hg (range, 6 to 19 mm Hg), and the mean number of antiglaucoma medication was reduced to 1.0±1.6 (PCO2-laser ablation system allows precise and easy creation of the scleral space and ablation of Schlemm canal. This technique has been shown to be as efficient as the standard NPDS surgery in terms of IOP-lowering effect. This would render the deep sclerectomy an easier glaucoma surgery.

  2. High-resolution smile measurement and control of wavelength-locked QCW and CW laser diode bars (United States)

    Rosenkrantz, Etai; Yanson, Dan; Klumel, Genady; Blonder, Moshe; Rappaport, Noam; Peleg, Ophir


    High-power linewidth-narrowed applications of laser diode arrays demand high beam quality in the fast, or vertical, axis. This requires very high fast-axis collimation (FAC) quality with sub-mrad angular errors, especially where laser diode bars are wavelength-locked by a volume Bragg grating (VBG) to achieve high pumping efficiency in solid-state and fiber lasers. The micron-scale height deviation of emitters in a bar against the FAC lens causes the so-called smile effect with variable beam pointing errors and wavelength locking degradation. We report a bar smile imaging setup allowing FAC-free smile measurement in both QCW and CW modes. By Gaussian beam simulation, we establish optimum smile imaging conditions to obtain high resolution and accuracy with well-resolved emitter images. We then investigate the changes in the smile shape and magnitude under thermal stresses such as variable duty cycles in QCW mode and, ultimately, CW operation. Our smile measurement setup provides useful insights into the smile behavior and correlation between the bar collimation in QCW mode and operating conditions under CW pumping. With relaxed alignment tolerances afforded by our measurement setup, we can screen bars for smile compliance and potential VBG lockability prior to assembly, with benefits in both lower manufacturing costs and higher yield.

  3. A randomized, open-label, controlled trial to evaluate the antimicrobial and surgical effect of CO2laser treatment in diabetic infected foot ulcers: DULCIS (diabetic ulcer, CO2laser, and infections) study. (United States)

    Monami, M; Scatena, A; Zannoni, S; Aleffi, S; Mirabella, C; Giannoni, L; Mannucci, E


    Debridement of fibrin and necrotic tissue from the ulcer surface is an important component of the treatment of diabetic ulcers. A possible alternative to standard lancets is represented by CO 2 laser, which vaporizes necrotic tissues together with any pathogen. The present trial is aimed at verifying the effect of a CO 2 laser on bacterial load in the debridement of infected diabetic foot ulcers. In this open-label randomized controlled trial (NCT02677779), patients with diabetes and an infected foot ulcers were randomized to either CO 2 laser or traditional debridement. The reduction (%) of bacterial load with CO 2 laser was significantly greater than in control group [-99.9 (-100.0; -90.0) vs. -50.0 (-96.0; -75.0), p = 0.049]. Similarly, a significantly greater reduction (%) of the fraction of ulcer area covered by fibrin was obtained in the intervention group [-84.1 (-95.0; -72.2) vs. -46.9 (-69.5; -40.8), p = 0.038]. Debridement of ulcers with CO 2 laser significantly reduces bacterial load and fibrin-covered areas, and could be of help in the treatment of diabetic foot ulcer.

  4. Promotional effects of CO2 laser on neoplastic lesions in hamsters (United States)

    Kingsbury, Jeffrey S.; Margarone, Joseph E., III; Satchidanand, S.; Liebow, Charles


    Surgical incision may have promotional effects on neoplastic lesions, possibly through release of tissue growth factors (e.g., EGF, FGF(beta) , IGF, TGF(alpha) ). The CO2 laser may precipitate altered release of these factors. To test this, .5 cm laser, and scalpel incisions were made into fields treated by application of .5% DMBA in acetone, 3 times a week for 6 weeks (group 1) and 12 weeks (group 2). DMBA is a complete carcinogen (initiator and promoter). At 6 weeks, chemically, but not histologically, definable premalignant lesions are seen. Treatment for 12 weeks causes histologic neoplasia which can be graded with T-N-M classification. For both groups, the surgical sites were examined clinically and histologically 4 weeks post-op in a blind fashion. Standard criteria were utilized for defining neoplasia. For group 1, 3 out of 6 laser treated animals developed large exophytic squamous cell carcinomas, but no lesions developed in 12 contralateral, 3 control and 3 scalpel treated pouches. For group 2, 12 of 16 laser treated animals developed tumor with mean grade of 1.75 and mean size of 7.4 mm, 5 of 6 scalpel treated animals developed tumor with mean grade of 1.83 and mean size of 3.6 mm and 3 of 6 control animals developed tumor with mean grade of 1.00 and mean size of 1.5 mm. By the Student 't' test on the binomial distribution lasers cause significant promotion (p wound site by increased release of growth factors.

  5. Growth of Co2MnAl Thin Films by Pulsed Laser Deposition

    Directory of Open Access Journals (Sweden)

    Isber Samih


    Full Text Available The effects of the deposition temperature and laser energy on the characteristics of Co2MnAl films deposited on GaAs substrates were investigated. The grown films were characterized by AFM for film roughness and surface topography. Film thickness and elemental composition were measured using Rutherford Back Scattering (RBS technique, while crystalline structure and phase composition were investigated by XRD. The RBS measurements showed that the stochiometry of the films was satisfactory and very close to that of the target Co: 0.5, Mn: 0.25, Al: 0.25. The thickness of the films was found to increase as the laser energy was increased from 200 to 400 mJ, in particular for the films deposited at 400 °C. We also found an increase in the films thicknesses as the deposition temperature was increased for the samples grown at 200 and 300 mJ. The best film quality as deduced from XRD, RBS and AFM results for producing these single layers were those deposited at 600 °C with the laser energy at 300 mJ.

  6. Cavitation at the air/water interface induced by CO2 laser: formation, dynamics and mechanism (United States)

    Hu, Man; Wang, Feng; Deng, Daosheng


    We report CO2-laser-induced cavitation at the interface between air and water, since strong photo-thermal effect of water occurs at the infrared wavelength. Using high-speed camera, we record explosive evaporation and the evolution of cavitation at the interface. By analyzing the growth dynamics of cavitation at various experimental conditions, we identify two stages of its growth associated with different mechanisms correspondingly. One stage is an initial faster expanding process driven by the influx of dissolved gas expelled from the surrounding water due to laser heating; and the other stage is a subsequent slower isobaric expanding process related with liquid properties. More quantitatively, we find that the evolution of cavitation at first stage is characterized by scaling law with an exponent of 1/3 for its diameter as a function of time, while its evolution at the second stage can be well described by Rayleigh-Plesset theory. This study of interfacial cavitation due to photo-thermal effect might have implications for solar-steam technology and infrared-laser surgery as well.

  7. Advancement of the O2 Subsystem to Demonstrate Retrieval of XCO2 Using Simultaneous Laser Absorption Spectrometer Integrated Column Measurements of CO2 and O2 (United States)

    National Aeronautics and Space Administration — Achieve scalability of a 1.26 µm fiber Raman amplifier (FRA) to 5W with an optical-to-optical efficiency of >50%, that is compatible with ITT’s modulated CW Laser...

  8. Experimental comparison of laser energy losses in high-quality laser-oxygen cutting of low-carbon steel using radiation from fibre and CO2 lasers (United States)

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


    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 CO2 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-3; this value is the same for the two lasers and does not depend on the sheet thickness.

  9. CW laser properties of Nd:GdYAG, Nd:LuYAG, and Nd:GdLuAG mixed crystals (United States)

    Di, J. Q.; Xu, X. D.; Li, D. Z.; Zhou, D. H.; Wu, F.; Zhao, Z. W.; Xu, J.; Tang, D. Y.


    Three mixed crystals, Nd:GdYAG, Nd:LuYAG, and Nd:GdLuAG, were grown by Czochralski method. We report the continuous-wave (CW) Nd:GdYAG, Nd:LuYAG, and Nd:GdLuAG laser operation under laser diode pumping. The maximum output powers are 4.11, 5.31, and 7.47 W, with slope efficiency of 73.0, 55.3, and 57.1%, respectively. With replacing Lu3+ or Y3+ ions with large Gd3+ ions, the pump efficiency increases.

  10. High-pressure continuously tunable CO2 lasers and molecular laser ...

    Indian Academy of Sciences (India)


    Jan 5, 2014 ... In addition to the design and construction of suitable pulse compression subsystems, also crucially important is the development of voltage-controlled pulse power supply suit- able to charge the initial storage energy capacitors, and which sensitively determines the eventual time jitter of the optical laser ...

  11. Efficacy of a new fractional CO2 laser in the treatment of photodamage and acne scarring. (United States)

    Katz, Bruce


    This study evaluates the efficacy and safety of a novel fractional CO(2) laser device for improving facial rhytids, hyperpigmentation, enlarged pores, skin laxity, and acne scarring. Subjects (n= 15) were treated three to five times at 3-week intervals. Biopsy specimens were used to evaluate healing response and neocollagenesis. Clinical improvement was rated on a quartile rating scale from digital photographs. Subject discomfort during treatment was evaluated on a scale of 0 to 5. Fourteen subjects who completed the study achieved good to excellent improvement in overall appearance, with 60% rated excellent. Improvement in photodamage was good to excellent in 92% of subjects, and reduction in rhytids was good to excellent in 85%. A total of 79% of subjects achieved good to excellent improvement in pore sizes and skin laxity. Subject discomfort during treatment was 3.0 +/- 0.7. Erythema persisted for 2-3 days, and subjects resumed normal activities 1-2 days after the procedure. Histological slides after a single treatment showed new collagen formation. The SmartSkin fractional CO(2) system (Cynosure, Inc., Westford, MA, USA) provides significant improvement for the treatment of facial wrinkles, hyperpigmentation, pore size, and skin laxity associated with photodamage.

  12. Two- and three-body fragmentation of CO 2 + induced by intense ultrashort laser pulses (United States)

    Rajput, Jyoti; Ablikim, U.; Zohrabi, M.; Jochim, Bethany; Berry, Ben; Carnes, K. D.; Esry, B. D.; Ben-Itzhak, I.


    We have studied the fragmentation dynamics of a CO2+molecular-ion beam in the strong-field regime using >= 32 fs laser pulses (about 795 nm and 1x 1016 W/ cm2) . A coincidence three-dimensional momentum imaging method was used to measure all ionic and neutral fragments formed during this multiphoton process. The angular distributions for the dominant two-body fragmentation channels CO+ + O, CO2+ + O and CO+ + O+ show two features, one predominantly aligned with the polarization axis and the other close to isotropic. The angular distributions for the three-body channels C+ + O+ + O and C+ + O+ + O+, populated via dissociative ionization, show the polarization axis lying preferentially in the molecular plane. We will discuss the kinetic energy release, angular distributions and relative production probability of the observed two- and three-body fragmentation channels. This work was supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy. BJ was also supported by DOE-SCGF (DE-AC05- 06OR23100).

  13. Nickel Nanoparticles Production using Pulsed Laser Ablation under Pressurized CO2 (United States)

    Mardis, Mardiansyah; Takada, Noriharu; Machmudah, Siti; Diono, Wahyu; Kanda, Hideki; Sasaki, Koichi; Goto, Motonobu


    We used nickel (Ni) plate as a target and irradiated pulse laser ablation with a fundamental wavelength of 1064 nm under pressurized CO2. The Ni plate was ablated at various pressure (5-15 MPa), temperature (15-80°), and irradiation time (3-30 min). The method successfully generated Ni nanoparticles in various shape and size. Generated Ni nanoparticles collected on a Si wafer and the ablated Ni plate were analyzed by Field Emission Scanning Electron Microscope (FE-SEM). With changing pressure and temperature, the structures of Ni nanoparticles also changed. The shape of generated particles is sphere-like structure with diameter around 10--100 nm. Also it was observed that a network structure of smaller particles was fabricated. The mechanism of nanoparticles fabrication could be explained as follows. Ablated nickel plate melted during the ablation process and larger particles formed, then ejected smaller spherical nanoparticles, which formed nanoclusters attached on the large particles. This morphology of particles was also observed for gold and silver nanoparticles with same condition. Further, the optical emission intensity from ablation plasma and the volume of the ablated crater were also examined under pressurized CO2.

  14. HOS cell adhesion on Ti6Al4V ELI texturized by CO2 laser (United States)

    Sandoval-Amador, A.; Bayona–Alvarez, Y. M.; Carreño Garcia, H.; Escobar-Rivero, P.; Y Peña-Ballesteros, D.


    In this work, the response of HOS cells on Ti6Al4V ELI textured surfaces by a CO2 laser was evaluated. The test surfaces were; smooth Ti6Al4V, used as the control, and four textured surfaces with linear geometry. These four surfaces had different separation distances between textured lines, D1 (1000 microns), D2 (750 microns), D3 (500 microns) and D4 (250 microns). Toxicity of textured surfaces was assessed by MTT and the cellular adhesion test was performed using HOS ATCC CRL 1543 line cells. This test was done after 5 days of culture in a RPMI 1640 medium supplemented with 10% fetal bovine serum and 1% antibiotics. The results showed that the linear textures present 23% toxicity after 30 days of incubation, nevertheless, the adhesion tests results are inconclusive in such conditions and therefore the effect of the line separation on the cell adhesion cannot be determined.

  15. Welding of zircalloy-2 and zircalloy-4 by CO2 laser and by TIG

    International Nuclear Information System (INIS)

    Ram, V.


    This study deals with the welding of zircaloy-2 and zircaloy-4 by means of two techniqes, namely tungsten inert gas welding and CO 2 laser welding. Suitable devices and jigs were developed and manufactured to allow the welding of flat specimens and cylindrical specimens. The optimal welding parameters for the two welding methods were determined. The quality of the welds was determined by tensile strength tests at room temperature and by determining the corrosion resistance to steam at temprature of 450 deg C, 550 deg C, and at 650 deg C. The influence of the weld on the microstructure of the material, on its composition and its crystallographic structure was investigated. Analysis of fracture surfaces of the tensile specimens was carried out with a scanning electron microscope. (author)

  16. CO2 Laser Excision of a Pyogenic Granuloma Associated with Dental Implants: A Case Report and Review of the Literature. (United States)

    Truschnegg, Astrid; Acham, Stephan; Kqiku, Lumnije; Beham, Alfred; Jakse, Norbert


    This article reports the CO2 laser excision of a pyogenic granuloma related to dental implants and reviews the current literature on this pathology in association with dental implants. Five publications describe pyogenic granulomas related to dental implants, and a further one describes the removal of such a lesion with an Er:YAG laser; removal with a CO2 laser is not reported. A 67-year-old male patient presented with a hyperplastic gingival lesion around two implants in the left lower jaw. The hyperplastic tissue was removed with a CO2 laser (Lasram; model OPAL 25, 25 W continuous wave, 10.600 nm, gas laser), and a vestibuloplasty was performed. The excised tissue was examined histopathologically. The patient was followed up after 4 weeks, 6 weeks, 6 months, and 1 year, and a panoramic X-ray was also made. There were no complications during surgery or follow-up. The panoramic X-ray taken 1 year after excision showed neither vertical bone loss nor impaired osseointegration of the implant. Histopathology reported a pyogenic granuloma. After vestibuloplasty, the height of the fixed mucosa was satisfactory. The CO2 laser seems to be a safe and appropriate tool for removal of a pyogenic granuloma in close proximity to dental implants. The laser parameters must, however, be chosen carefully and any additional irritants should be excluded to prevent a recurrence.

  17. Prospective evaluation of CO2 laser-assisted sclerectomy surgery (CLASS) with Mitomycin C. (United States)

    Cutolo, Carlo Alberto; Bagnis, Alessandro; Scotto, Riccardo; Bonzano, Chiara; Traverso, Carlo Enrico


    Our purpose was to evaluate the clinical safety and efficacy of CO 2 laser-assisted sclerectomy surgery (CLASS) with Mitomycin C (MMC) in open angle glaucoma (OAG). This was a prospective, uncontrolled, interventional case series. All subjects underwent CLASS procedure by a single surgeon. After the dissection of a partial thickness scleral flap, topical MMC 0.2 mg/ml was applied to the sclera and the conjunctiva for 3 min. The CO 2 laser with a beam-manipulating system was used to ablate the scleral tissue and expose the Schlemm's canal area. Primary outcomes: intraocular pressure (IOP) change, number of IOP-lowering medicaments change. Adverse events were evaluated as secondary outcomes. Twenty-one eyes of 21 patients underwent the CLASS procedure. Thirteen were primary OAG (62%), two normal pressure glaucoma (10%), three exfoliative glaucoma (14%) and three others secondary OAG. With a mean (SD) follow-up of 15.3 (5.9) months, the IOP changed from 25.4 (6.7) mmHg at baseline to 10.9 (3.4) mmHg al the last visit. Mean reduction of IOP was -14.5 mmHg (95% CI, -17.7 to -11.2, P filtration area that was successfully managed with office-based procedures. In one case (5%), CLASS was converted to trabeculectomy due to intraoperative perforation of the ablated area. There was one case of hypotony maculopathy successfully treated with placement of additional transconjunctival scleral flap sutures. The CLASS procedure with MMC is clinically safe and effective maintaining a large reduction in IOP and in the number of IOP-lowering medications with a mean follow-up of 15 months. Iris adhesion at the filtrating area warrants further evaluation and possibly reflects the surgeon's learning curve.

  18. CO2 laser-assisted sclerectomy surgery, part II: multicenter clinical preliminary study. (United States)

    Geffen, Noa; Ton, Yokrat; Degani, Joshua; Assia, Ehud I


    To evaluate the efficacy of CO2 laser-assisted sclerectomy surgery (CLASS) in primary and pseudoexfoliative open-angle glaucoma. Patients for primary filtration surgery underwent CLASS with a CO2 laser system (OT-134-IOPtiMate, IOPtima Ltd., Ramat Gan, Israel). This self-controlled system gradually ablates and removes scleral layers until percolating fluid absorbs the energy, attenuating further tissue ablation. Intraocular pressure (IOP) was measured at baseline, 1, 2, 4, and 6 weeks, and 3, 6, and 12 months, respectively. Complete success was defined as 5≤IOP≤18 mm Hg and 20% IOP reduction with no medication at a 12-month endpoint visit, and qualified success as the same IOP range with or without medication. Thirty of 37 patients completed 12 months of follow-up. Mitomycin C was used in 25 procedures (83.3%). The mean baseline IOP of 26.3±7.8 mm Hg (mean±SD) dropped to 14.4±3.4 and 14.3±3.1 mm Hg at 6 and 12 months, respectively, with 42.4% and 40.7% IOP reduction at 6 and 12 months, respectively (P<0.001). Complete success was achieved by 76.7% and 60% of the patients at 6 and 12 months, respectively, whereas qualified success was achieved by 83.3% and 86.6% of the patients at 6 and 12 months, respectively. Complications were mild and transitory with no sequela. Short-term and intermediate results suggest that CLASS may become a simple, safe, and effective means of choice for the treatment of open-angle glaucoma.

  19. CW and Q-switched GGG/Er:Pr:GGG/GGG composite crystal laser at 2.7 µm (United States)

    You, Z. Y.; Wang, Y.; Sun, Y. J.; Xu, J. L.; Zhu, Z. J.; Li, J. F.; Wang, H. Y.; Tu, C. Y.


    We report the continuous-wave (CW) and passively Q-switched laser operations of a GGG/Er:Pr:GGG/GGG composite crystal at about 2.7 µm. Owing to the alleviation of the thermal lensing effect, the CW laser with a maximum output power of 463 mW was obtained with a slope efficiency of 15.5%. Based on the broadband saturable absorption property, a graphene saturable absorber (SA) mirror was fabricated and employed for realizing the Q-switched mid-infrared laser. Under an absorbed pump power of 2.47 W, an average output power of 186 mW was generated with a slope efficiency of 12.3%. The pulse width and the repetition rate of the laser were 360 ns and 120.5 kHz, respectively. These results indicate that the Er:Pr:GGG crystal, with the relatively lower upper-level lifetime, shows great promise for generating a short pulsed 2.7 µm mid-infrared laser using the graphene SA.

  20. The synergistic effects of CO2 laser treatment with calcium silicate cement of antibacterial, osteogenesis and cementogenesis efficacy (United States)

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


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

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

    International Nuclear Information System (INIS)

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


    Calcium silicate-based material (CS) has been successfully used in dental clinical applications. Some researches show that the antibacterial effects of CO 2 laser irradiation are highly efficient when bacteria are embedded in biofilm, due to a photo-thermal mechanism. The purpose of this study was to confirm the effects of CO 2 laser irradiation on CS, with regard to both material characterization and human periodontal ligament cell (hPDLs) viability. CS was irradiated with a dental CO 2 laser using directly mounted fiber optics in wound healing mode with a spot area of 0.25 cm 2 , and then stored in an incubator at 100% relative humidity and 37 °C for 1 d to set. The hPDLs cultured on CS were analyzed, along with their proliferation and odontogenic differentiation behaviors. The results indicate that the CO 2 laser irradiation increased the amount of Ca and Si ions released from the CS, and regulated cell behavior. CO 2 laser-irradiated CS promoted cementogenic differentiation of hPDLs, with the increased formation of mineralized nodules on the substrate’s surface. It also up-regulated the protein expression of multiple markers of cementogenic and the expression of cementum attachment protein. The current study provides new and important data about the effects of CO 2 laser irradiation on CS. Taking cell functions into account, the Si concentration released from CS with laser irradiated may be lower than a critical value, and this information could lead to the development of new regenerative therapies for dentin and periodontal tissue. (letter)

  2. Tratamiento del rinofima con láser de CO2: Presentación de un caso Treatment of rhinophyma with CO2 laser: A case report

    Directory of Open Access Journals (Sweden)

    J.L. Cebrián Carretero


    Full Text Available Introducción. El rinofima es una alteración cutánea de la región nasal que produce problemas estéticos importantes. Describimos nuestra experiencia en un caso de rinofima avanzado y su resolución por medio de una técnica sencilla. Material y métodos. Previa desinfección cutánea se realizó anestesia infiltrativa y bloqueo troncular de nervios infraorbitarios y etmoidales. A continuación se realizó la resección de casi todo el espesor cutáneo con un láser de CO2 Lumenis Sharplan conservando la dermis profunda para permitir la curación por segunda intención. Posteriormente se aplicó vaselina y se realizaron curas y lavados diarios. El paciente fue dado de alta al día siguiente de la intervención. Resultados. Los resultados estéticos fueron muy buenos. El dolor postoperatorio fue controlado con analgesia habitual. En la primera semana se objetivaba un buen grado de cicatrización. A los 2 meses la reepitelización fue completa y ya no se observaban costras ni eritema. Conclusión. La utilización del láser de CO2 en el tratamiento del rinofima avanzado logra unos excelentes resultados estéticos con una morbilidad y riesgo operatorio mínimos.Introduction. Rhinophyma is a skin alteration of the nasal region that causes considerable aesthetic problems. We describe our experience with a case of advanced rhinophyma and its resolution by means of a simple technique. Materials and methods. The skin area was disinfected beforehand, anaesthesia infiltration and the infraorbital and ethmoidal nerve trunks were blocked. Then, using a Lumenis Sharplan CO2 laser almost the complete skin thickness was resected while preserving the deep dermis layer so as to allow second intention healing. Later, Vaseline was applied and the area was treated daily. The patient was discharged the day after the intervention. Results. The aesthetic results were very good. Postoperative pain was controlled with standard analgesics. Adequate healing was

  3. Design and optimisation of a pulsed CO2 laser for laser ultrasonic applications

    CSIR Research Space (South Africa)

    Forbes, A


    Full Text Available quality, a pulse of short duration (<100 ns), as well as a minimum energy (>200 mJ) and pulse repetition rate (>200 Hz) for the process to be suitable for industrial applications. Furthermore, since these systems will typically be used in a production... ensures a good signal-to-noise ratio, while a higher repetition rate allows more samples to be tested in a given time, thereby increasing productivity. The LU signal is a product of the effi- ciency of the laser pulse in generating ultrasound...

  4. Growth dynamics of carbon-metal particles and nanotubes synthesized by CO2 laser vaporization (United States)

    Kokai, F.; Takahashi, K.; Yudasaka, M.; Iijima, S.

    To study the growth of carbon-Co/Ni particles and single-wall carbon nanotubes (SWNTs) by 20 ms CO2 laser-pulse irradiation of a graphite-Co/Ni (1.2 at.%) target in an Ar gas atmosphere (600 Torr), we used emission imaging spectroscopy and shadowgraphy with a temporal resolution of 1.67 ms. Wavelength-selected emission images showed that C2 emission was strong in the region close to the target (within 2 cm), while for the same region the blackbody radiation from the large clusters or particles increased with increasing distance from the target. Shadowgraph images showed that the viscous flow of carbon and metal species formed a mushroom or a turbulent cloud spreading slowly into the Ar atmosphere, indicating that particles and SWNTs continued to grow as the ejected material cooled. In addition, emission imaging spectroscopy at 1200 °C showed that C2 and hot clusters and particles with higher emission intensities were distributed over much wider areas. We discuss the growth dynamics of the particles and SWNTs through the interaction of the ambient Ar with the carbon and metal species released from the target by the laser pulse.

  5. Photoacoustic CO2 sensor based on a DFB diode laser at 2.7 μm (United States)

    Wolff, M.; Germer, M.; Groninga, H. G.; Harde, H.


    We present a new detection scheme for carbon dioxide (CO{2}) based on a custom-made room temperature distributed feedback (DFB) diode laser at 2.7 μm, currently representing one of the lasers with the highest emission wavelength of its kind. The detector's especially compact and simple set-up is based on photoacoustic spectroscopy (PAS). This method makes use of the transformation of absorbed modulated radiation into a sound wave. The sensor enables a very high detection sensitivity for CO{2} in the ppb range. Furthermore, the carefully selected spectral region as well as the narrow bandwidth and wide tunability of the single-mode laser ensure an excellent selectivity. Even measurements of different CO{2} isotopes can be easily performed. This enables applications in industrial sensing and medical diagnostics (e.g. 13C-breath tests).

  6. Raman spectroscopy differentiates squamous cell carcinoma (SCC) from normal skin following treatment with a high-powered CO2 laser. (United States)

    Fox, Sara A; Shanblatt, Ashley A; Beckman, Hugh; Strasswimmer, John; Terentis, Andrew C


    The number of cases of non-melanoma skin cancer (NMSC), which include squamous cell carcinoma (SCC) and basal cell carcinoma (BCC), continues to rise as the aging population grows. Mohs micrographic surgery has become the treatment of choice in many cases but is not always necessary or feasible. Ablation with a high-powered CO2 laser offers the advantage of highly precise, hemostatic tissue removal. However, confirmation of complete cancer removal following ablation is difficult. In this study we tested for the first time the feasibility of using Raman spectroscopy as an in situ diagnostic method to differentiate NMSC from normal tissue following partial ablation with a high-powered CO2 laser. Twenty-five tissue samples were obtained from eleven patients undergoing Mohs micrographic surgery to remove NMSC tumors. Laser treatment was performed with a SmartXide DOT Fractional CO2 Laser (DEKA Laser Technologies, Inc.) emitting a wavelength of 10.6 μm. Treatment levels ranged from 20 mJ to 1200 mJ total energy delivered per laser treatment spot (350 μm spot size). Raman spectra were collected from both untreated and CO2 laser-treated samples using a 785 nm diode laser. Principal Component Analysis (PCA) and Binary Logistic Regression (LR) were used to classify spectra as originating from either normal or NMSC tissue, and from treated or untreated tissue. Partial laser ablation did not adversely affect the ability of Raman spectroscopy to differentiate normal from cancerous residual tissue, with the spectral classification model correctly identifying SCC tissue with 95% sensitivity and 100% specificity following partial laser ablation, compared with 92% sensitivity and 60% selectivity for untreated NMSC tissue. The main biochemical difference identified between normal and NMSC tissue was high levels of collagen in the normal tissue, which was lacking in the NMSC tissue. The feasibility of a combined high-powered CO2 laser ablation, Raman diagnostic procedure for the

  7. Rabi oscillations and rapid-passage effects in the molecular-beam CO2-laser Stark spectroscopy of CH3F

    International Nuclear Information System (INIS)

    Adam, A.G.; Gough, T.E.; Isenor, N.R.; Scoles, G.


    sub-Doppler molecular-beam laser Stark spectroscopy has been employed to produce high-contrast Rabi oscillations in the ν 3 band of CH 3 F. By varying the intensity of the cw CO 2 laser, up to five complete oscillations were observed before the phenomenon was washed out by rapid-passage effects and damping mechanisms. Besides being useful in clarifying key features of coherent ir molecular-beam spectroscopy, the observation of Rabi oscillations provides one of the most accurate means of directly measuring transition dipole moments. Analysis of the present data on three rovibrational transitions, Q(1,1) -1reverse arrow0, P(1,0) 0reverse arrow0, and R(1,1) 0reverse arrow1, has yielded a rotationless transition dipole moment of 0.21 +- 0.01 D for the ν 3 = 1reverse arrow0 vibration. This result is in agreement with values estimated from both band-intensity and absorption-coefficient data in the literature

  8. Influence of water layer thickness on hard tissue ablation with pulsed CO2 laser (United States)

    Zhang, Xianzeng; Zhan, Zhenlin; Liu, Haishan; Zhao, Haibin; Xie, Shusen; Ye, Qing


    The theory of hard tissue ablation reported for IR lasers is based on a process of thermomechanical interaction, which is explained by the absorption of the radiation in the water component of the tissue. The microexplosion of the water is the cause of tissue fragments being blasted from hard tissue. The aim of this study is to evaluate the influence of the interdependence of water layer thickness and incident radiant exposure on ablation performance. A total of 282 specimens of bovine shank bone were irradiated with a pulse CO2 laser. Irradiation was carried out in groups: without a water layer and with a static water layer of thickness ranging from 0.2 to 1.2 mm. Each group was subdivided into five subgroups for different radiant exposures ranging from 18 to 84 J/cm2, respectively. The incision geometry, surface morphology, and microstructure of the cut walls as well as thermal injury were examined as a function of the water layer thickness at different radiant exposures. Our results demonstrate that the additional water layer is actually a mediator of laser-tissue interaction. There exists a critical thickness of water layer for a given radiant exposure, at which the additional water layer plays multiple roles, not only acting as a cleaner to produce a clean cut but also as a coolant to prevent bone heating and reduce thermal injury, but also helping to improve the regularity of the cut shape, smooth the cut surface, and enhance ablation rate and efficiency. The results suggest that desired ablation results depend on optimal selection of both water layer thickness and radiant exposure.

  9. CW operation of high-power blue laser diodes with polished facets on semi-polar ( 20 2 ¯ 1 ¯ ) GaN substrates

    KAUST Repository

    Pourhashemi, A.


    Continuous wave (CW) operation of high-power blue laser diodes (LDs) with polished facets on semi-polar (202̅1̅) gallium nitride (GaN) substrates is demonstrated. Ridge waveguide LDs were fabricated using indium GaN waveguiding layers and GaN cladding layers. At a lasing wavelength of 452 nm, the peak two-facet CW output power from an LD with uncoated facets was 1.71 W at a current of 3 A, corresponding to an optical power density of 32.04 MW/cm2 on each facet. The dependence of output power on current did not change with repeated CW measurements, indicating that the polished facets did not degrade under high-power CW operation. These results show that polished facets are a viable alternative to cleaved or etched facets for high-power CW semi-polar LDs.

  10. Infrared imaging of CO2 laser ablation: implications for laser skin resurfacing (United States)

    Choi, Bernard; Barton, Jennifer K.; Chan, Eric K.; Thomsen, Sharon L.; Welch, Ashley J.


    Surface temperature measurements and CCD video imaging were performed during multiple pulse irradiation on in vivo rat skin. A TruPulse laser (100-microsecond pulsewidth, 3 mm X 3 mm spot size) was used at radiant exposures of 2.4 J/cm2 and 3.9 J/cm2 for all experiments. Temperatures were recorded with a thermal camera. During multiple pulse irradiation, one pulse per second was applied to a single site. A total of fifteen pulses were applied to a single spot. Irradiating with 2.4 J/cm2 pulses led to a slow temperature rise that reached steady state at approximately 200 degrees Celsius. Carbonization onset occurred after pulses 5 - 8. With a higher radiant exposure of 3.9 J/cm2, carbonization occurred after the third pulse; after the tenth pulse, focal tissue burning was visible, and the temperature oscillated around 350 degrees Celsius. Surface temperatures were measured during clinical scans. Areas of 3 cm X 3 cm were treated by the laser, which was moved across the tissue in a raster scan with 8 pulses per second. Each area was treated three times. From analysis of histological sections, the thermal damage as a function of pass number and radiant exposure was noted. Contrary to previous reports, the epidermis was not removed after the first pass. Indeed, after three passes, the epidermis was still present (Ho equals 2.4 J/cm2) or was severely fragmented (Ho equals 3.9 J/cm2).

  11. Bond strength of resin cement to CO2 and Er:YAG laser-treated zirconia ceramic

    Directory of Open Access Journals (Sweden)

    Shahin Kasraei


    Full Text Available Objectives It is difficult to achieve adhesion between resin cement and zirconia ceramics using routine surface preparation methods. The aim of this study was to evaluate the effects of CO2 and Er:YAG laser treatment on the bond strength of resin cement to zirconia ceramics. Materials and Methods In this in-vitro study 45 zirconia disks (6 mm in diameter and 2 mm in thickness were assigned to 3 groups (n = 15. In control group (CNT no laser treatment was used. In groups COL and EYL, CO2 and Er:YAG lasers were used for pretreatment of zirconia surface, respectively. Composite resin disks were cemented on zirconia disk using dual-curing resin cement. Shear bond strength tests were performed at a crosshead speed of 0.5 mm/min after 24 hr distilled water storage. Data were analyzed by one-way ANOVA and post hoc Tukey's HSD tests. Results The means and standard deviations of shear bond strength values in the EYL, COL and CNT groups were 8.65 ± 1.75, 12.12 ± 3.02, and 5.97 ± 1.14 MPa, respectively. Data showed that application of CO2 and Er:YAG lasers resulted in a significant higher shear bond strength of resin cement to zirconia ceramics (p < 0.0001. The highest bond strength was recorded in the COL group (p < 0.0001. In the CNT group all the failures were adhesive. However, in the laser groups, 80% of the failures were of the adhesive type. Conclusions Pretreatment of zirconia ceramic via CO2 and Er:YAG laser improves the bond strength of resin cement to zirconia ceramic, with higher bond strength values in the CO2 laser treated samples.

  12. Treatment of atrophic facial scars with combined use of high-energy pulsed CO2 laser and Er:YAG laser: a practical guide of the laser techniques for the Er:YAG laser. (United States)

    Cho, S I; Kim, Y C


    Although CO2 laser resurfacing provides substantial clinical improvement for atrophic facial scars, the CO2 laser often results in excessive thermal damage to the skin. It increases complications postoperatively. The Er:YAG laser ablates thinner layers of tissue than the CO2 laser with minimal thermal damage to the surrounding skin. To determine the efficacy of combined treatment of atrophic facial scars with high-energy pulsed CO2 laser and Er:YAG laser. One hundred fifty-eight patients were treated with a combination of high-energy pulsed CO2 laser and Er:YAG laser for atrophic facial scars. All patients were evaluated after 3 months of treatment. The scars improved 80-89% in 65 patients, 70-79% in 56 patients, more than 90% in 32 patients, 60-69% in 2 patients, and less than 60% in 3 patients after laser treatment. Treatment of atrophic facial scars with combined use of high-energy pulsed CO2 laser and Er:YAG laser is a very effective and useful method.

  13. Progress in Cr and Fe doped ZnS/Se mid-IR CW and femtosecond lasers (United States)

    Vasilyev, Sergey; Moskalev, Igor; Mirov, Mike; Smolski, Viktor; Martyshkin, Dmitry; Fedorov, Vladimir; Mirov, Sergey; Gapontsev, Valentin


    This paper summarizes recent improvements of output characteristics of polycrystalline Cr:ZnS/Se master oscillators in Kerr-Lens-Mode-Locked regime. We developed a flexible design of femtosecond polycrystalline Cr:ZnS and Cr:ZnSe lasers and amplifiers in the spectral range 2-3 μm. We obtained few-optical-cycle pulses with multi-Watt average power in very broad range of repetition rates 0.08-1.2 GHz. We also report on efficient nonlinear frequency conversion directly in the polycrystalline gain elements of ultra-fast lasers and amplifiers. In this work we also report on recent progress in spinning ring gain element technology and report to the best of our knowledge the highest output power of 9.2 W Fe:ZnSe laser operating in CW regime at 4150nm.

  14. The feasibility of TEA CO2 laser-induced plasma for spectrochemical analysis of geological samples in simulated Martian conditions (United States)

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


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

  15. Influence of CO2 pressure on the emission spectra and plasma parameters in underwater laser-induced breakdown spectroscopy. (United States)

    Goueguel, Christian L; McIntyre, Dustin L; Jain, Jinesh C


    Optical emission spectroscopic studies have been carried out to investigate the pressure effect of CO2 on laser-produced underwater plasma. The plasma was generated by focusing 1064 nm, 6 ns pulses from a Nd:YAG laser in a CO2-bearing solution. The temporal evolution of the continuum emission, Sr and Ba lines, and plasma electron density and temperature was characterized under CO2 pressure ranging from 10 to 300 bars. The electron density measurements were made using the Stark broadening of the 455.40 nm Ba II line, while the temperature measurements have been performed by the Saha-Boltzmann method using the Sr I-II lines at 460.73 and 407.77 nm, respectively. It was found that CO2 pressure has little effect on the emission line intensity and signal-to-background ratio. The electron density and the temperature are found to be independent of the CO2 pressure at early times. When time becomes longer, the electron density exhibits an appreciable rise as the CO2 pressure increases, while the temperature is found to be unchanged.

  16. Selective Removal of Natural Occlusal Caries by Coupling Near-infrared Imaging with a CO2 Laser


    Tao, You-Chen; Fried, Daniel


    Laser removal of dental hard tissue can be combined with optical, spectral or acoustic feedback systems to selectively ablate dental caries and restorative materials. Near-infrared (NIR) imaging has considerable potential for the optical discrimination of sound and demineralized tissue. Last year we successfully demonstrated that near-IR images can be used to guide a CO2 laser ablation system for the selective removal of artificial caries lesions on smooth surfaces. The objective of this stud...

  17. Fractional CO2 Laser Treatment of the Vestibule for Patients with Vestibulodynia and Genitourinary Syndrome of Menopause: A Pilot Study. (United States)

    Murina, Filippo; Karram, Mickey; Salvatore, Stefano; Felice, Raffaele


    Chronic vulvar pain and burning remains one of the most perplexing problems faced by practicing gynecologists. To evaluate the effectiveness and safety of the application of micro-ablative fractional CO 2 laser to the vulvar vestibule in the management of patients with vulvar pain from vestibulodynia or genitourinary syndrome of menopause. Patients (N = 70) underwent fractional micro-ablative CO 2 laser treatment for vestibular pain plus vestibulodynia (n = 37) or genitourinary syndrome of menopause (n = 33). Inclusion criteria were the existence of vestibular atrophic changes and the absence of moderate or severe pelvic floor hypertonic dysfunction. A visual analog scale of pain and the Marinoff score of dyspareunia were chosen to evaluate improvement. Grading of vestibular health also was quantified using a four-point scoring system (0 = no atrophy, 3 = severe atrophy). Data were collected at baseline, at weeks 4, 8, and 12, and 4 months after the final treatment. For visual analog scale and dyspareunia scoring and for the overall vestibular health index scoring, statistically significant improvement was noted after three sessions of vestibular fractional CO 2 laser treatment. Improvement gradually increased throughout the study period and was maintained through the 4-month follow-up visit. There was no statistically significant difference in outcomes between the two study groups. No adverse events from fractional CO 2 laser treatment were noted. Overall, 67.6% of patients stated significant improvement from the laser procedure. This preliminary case series showed encouraging results using fractional CO 2 laser treatment of the vestibule in women with vestibulodynia and genitourinary syndrome of menopause. Copyright © 2016 International Society for Sexual Medicine. Published by Elsevier Inc. All rights reserved.

  18. Comparison of multiple rebond shear strengths of debonded brackets after preparation with sandblasting and CO2 laser

    Directory of Open Access Journals (Sweden)

    Mojgan Kachoei


    Full Text Available Background. Failure of orthodontic bracket bonds is a common occurrence during orthodontic treatment. Different techniques have been suggested in the literature to remove resin residues from the bracket bases and enamel surfaces to prepare the surfaces again after debonding. This study attempted to compare multiple rebond shear strengths (SBS of debonded brackets following preparation with sandblasting and CO2 laser. Methods. The brackets were bonded on 30 human and bovine maxillary central incisors using self-curing composite resin. SBS was measured using Hounsfield testing machine. The brackets were rebonded for two other times after composite resin residues on their surfaces were removed, either with air abrasion or CO2 laser. The debonded brackets and enamel surfaces were also evaluated after each debonding procedure under a stereomicroscope in order to determine adhesive remnant index (ARI. SBS of debonded brackets after each step were compared between sandblast and CO2 laser groups. Results. We observed significant differences in SBS values between pre-recycling and first (P = 0.04, second (P = 0.007 and third recycling (P = 0.007 with laser. Recycling with sandblasting resulted in a decrease in SBS after the first and second recycling procedure; however, the SBS increased after the third recycling procedure, with no significant differences. Conclusion. SBS of brackets after recycling with sandblasting and laser beams was not significantly different, and both were at a favorable level. However, repeating the recycling procedure with sandblasting resulted in more favorable SBS compared to laser.

  19. A CO2 laser based system for the production of nanoscaled powders

    International Nuclear Information System (INIS)

    Kurland, H.-D.; Schindler, K.; Staupendahl, G.; Oestreich, Ch.; Loogk, M.; Mueller, E.


    Nowadays the world-wide industrial competition is increasingly determined by the use of new materials which allow optimised and in part totally new qualities of products or the production of more compact components. Thereby the importance of ultrafine ceramic powders with grain sizes of only a few nanometers rises rapidly. These powders show some interesting physical and chemical features which result from the extremely small dimensions of their particles, for example very high specific surfaces, high surface energy or special behaviour in the phase transformation. Their thermodynamic and kinetic (short diffusion lengths) parameters are mirrored in high sintering activities and hence relatively low sintering temperatures as well as very special properties of the sintered materials, especially the possibility of super plasticity. Nanoscaled powders also have a broad potential for the production of thin layers for example in the electronics industry or as part of composite materials with components of lower thermal stability. At present different technologies for the manufacturing of nanoscaled powders are intensively used and developed. In this paper a technique for the production of ceramic nanopowders by evaporation of solid starting materials with CO 2 laser radiation is presented

  20. Dural reconstruction by fascia using a temperature-controlled CO2 laser soldering system (United States)

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


    Conventional methods for dura repair are normally based on sutures or stitches. These methods have several disadvantages: (1) The dura is often brittle, and the standard procedures are difficult and time consuming. (2) The seal is leaky. (3) The introduction of a foreign body (e.g. sutures) may cause an inflammatory response. In order to overcome these difficulties we used a temperature controlled fiber optic based CO2 laser soldering system. In a set of in vitro experiments we generated a hole of diameter 10 mm in the dura of a pig corpse, covered the hole with a segment of fascia, and soldered the fascia to the edges of the hole, using 47% bovine albumin as a solder. The soldering was carried out spot by spot, and each spot was heated to 65° C for 3-6 seconds. The soldered dura was removed and the burst pressure of the soldered patch was measured. The average value for microscopic muscular side soldering was 194 mm Hg. This is much higher than the maximal physiological pressure of the CSF fluid in the brain, which is 15 mm Hg. In a set of in vivo experiments, fascia patches were soldered on holes in five farm pigs. The long term results of these experiments were very promising. In conclusion, we have developed an advanced technique for dural reconstruction, which will find important clinical applications.

  1. Measurement of the Nonlinearity of Heat-Flux Sensors Employing a CO_2 laser (United States)

    van der Ham, E. W. M.; Beer, C. M.; Ballico, M. J.


    Heat-flux sensors are widely used in industry to test building products and designs for resistance to bushfire, to test the flammability of textiles and in numerous applications such as concentrated solar collectors. In Australia, such detectors are currently calibrated by the National Measurement Institute Australia (NMIA) at low flux levels of 20 W \\cdot m^{-2}. Estimates of the uncertainty arising from nonlinearity at industrial levels (e.g. 50 kW \\cdot m^{-2} for bushfire testing) rely on literature information. NMIA has developed a facility to characterize the linearity response of these heat-flux sensors up to 110 kW \\cdot m^{-2} using a low-power CO_2 laser and a chopped quartz tungsten-halogen lamp. The facility was validated by comparison with the conventional flux-addition method, and used to characterize several Schmidt-Boelter-type sensors. A significant nonlinear response was found, ranging from (3.2 ± 0.9)% at 40 kW \\cdot m^{-2} to more than 8 % at 100 kW \\cdot m^{-2}. Additional measurements confirm that this is not attributable to convection effects, but due to the temperature dependence of the sensor's responsivity.

  2. CO 2 laser photoacoustic detection of ethylene emitted by diesel engines used in urban public transports (United States)

    Teodoro, C. G.; Schramm, D. U.; Sthel, M. S.; Lima, G. R.; Rocha, M. V.; Tavares, J. R.; Vargas, H.


    In this work, CO 2 laser photoacoustic spectroscopy was used to detect and monitor ethylene concentrations from about 0.6 ppmV up to 47 ppmV emitted by urban public transports in Campos dos Goytacazes city in Rio de Janeiro state, Brazil. The photoacoustic method proved to be a very sensitive and selective gas detection technique. As ethylene is a rather reactive compound due to its double bond between the two carbon atoms, it acts as one of the precursors for the tropospheric ozone generation, a gas species that is present in the photochemical smog, is an important greenhouse gas and whose formation is strongly associated with the presence of sun light and nitrogen oxide compounds. For this reason, ethylene renders itself an important pollutant in the atmosphere. In addition, the valid Brazilian legislation is only concerned with the total emission of hydrocarbons from the vehicle exhausts. It means that it does not discriminate the emission of some pollutant gas compounds, such as ethylene. This situation is greatly aggravated by the fact that most of the mass and cargo transport in Brazil is made by roads and powered by diesel oil.

  3. Tool feed influence on the machinability of CO(2) laser optics. (United States)

    Arnold, J B; Steger, P J; Saito, T T


    Influence of tool feed on reflectivity of diamond-machined surfaces was evaluated using materials (gold, silver, and copper) from which CO(2) laser optics are primarily produced. Fifteen specimens were machined by holding all machining parameters constant, except tool feed. Tool feed was allowed to vary by controlled amounts from one evaluation zone (or part) to another. Past experience has verified that the quality of a diamond-machined surface is not a function of the cutting velocity; therefore, this experiment was conducted on the basis that a variation in cutting velocity was not an influencing factor on the diamondturning process. Inspection results of the specimens indicated that tool feeds significantly higher than 5.1 micro/rev (200 microin./rev) produced detrimental effects on the machined surfaces. In some cases, at feeds as high as 13 microm/rev (500 microin./rev), visible scoring was evident. Those surfaces produced with tool feeds less than 5.1 microm/rev had little difference in reflectivity. Measurements indicat d that their reflectivity existed in a range from 96.7% to 99.3% at 10.6 microm.

  4. Influence of the electric field frequency on the performance of a RF excited CO2 waveguide laser

    NARCIS (Netherlands)

    Ochkin, V.N.; Witteman, W.J.; Ilukhin, B.I.; Kochetov, I.V.; Peters, P.J.M.; Udalov, Yu.B.; Tskhai, S.N.


    An analysis is presented of the effect of the RF frequency on the active media of CO2 waveguide lasers. It is found that the characteristics are improved with increasing RF frequency because the space charge sheath width decreases with increasing excitation frequency. We also found that the sheath

  5. CO2 Laser and Topical Fluoride Therapy in the Control of Caries Lesions on Demineralized Primary Enamel

    Directory of Open Access Journals (Sweden)

    R. A. Valério


    Full Text Available This study evaluated the effect of CO2 laser irradiation and topical fluoride therapy in the control of caries progression on primary teeth enamel. 30 fragments (3×3×2 mm from primary canines were submitted to an initial cariogenic challenge that consisted of immersion on demineralizing solution for 3 hours and remineralizing solution for 21 hours for 5 days. Fragments were randomly assigned into three groups (n=10: L: CO2 laser (λ=10.6 μm, APF: 1.23% acidulated phosphate fluoride, and C: no treatment (control. CO2 laser was applied with 0.5 W power and 0.44 J/cm2 energy density. Fluoride application was performed with 0.1 g for 1 minute. Cariogenic challenge was conducted for 5 days following protocol previously described. Subsurface Knoop microhardness was measured at 30 μm from the edge. Obtained data were subjected to analysis the variance (ANOVA and Duncan test with significance of 5%. It was found that the L group showed greater control of deciduous enamel demineralization and were similar to those of APF group, while being statistically different from C group (P≤0.05 that showed the lowest microhardness values. It was concluded that CO2 laser can be an additional resource in caries control progression on primary teeth enamel.

  6. CO2 laser and topical fluoride therapy in the control of caries lesions on demineralized primary enamel. (United States)

    Valério, R A; Rocha, C T; Galo, R; Borsatto, M C; Saraiva, M C P; Corona, S A M


    This study evaluated the effect of CO2 laser irradiation and topical fluoride therapy in the control of caries progression on primary teeth enamel. 30 fragments (3 × 3 × 2 mm) from primary canines were submitted to an initial cariogenic challenge that consisted of immersion on demineralizing solution for 3 hours and remineralizing solution for 21 hours for 5 days. Fragments were randomly assigned into three groups (n = 10): L: CO2 laser (λ = 10.6 μm), APF: 1.23% acidulated phosphate fluoride, and C: no treatment (control). CO2 laser was applied with 0.5 W power and 0.44 J/cm(2) energy density. Fluoride application was performed with 0.1 g for 1 minute. Cariogenic challenge was conducted for 5 days following protocol previously described. Subsurface Knoop microhardness was measured at 30 μm from the edge. Obtained data were subjected to analysis the variance (ANOVA) and Duncan test with significance of 5%. It was found that the L group showed greater control of deciduous enamel demineralization and were similar to those of APF group, while being statistically different from C group (P ≤ 0.05) that showed the lowest microhardness values. It was concluded that CO2 laser can be an additional resource in caries control progression on primary teeth enamel.

  7. TEA CO2 laser-induced reaction of CH3NO2 with CF2HCl: A ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 113; Issue 4. TEA CO2 laser-induced reaction of CH3NO2 with CF2HCl: A mechanistic study. Rajesh K Vatsa Sisir K Sarkar Jai P Mittal. Physical and Theoretical Volume 113 Issue 4 August 2001 pp 333-342 ...

  8. O emprego do laser de CO2 no controle da cárie dentária = The use of CO2 laser on dental on dental caries control

    Directory of Open Access Journals (Sweden)

    Rodrigues, Lidiany Karla Azevedo


    Full Text Available O laser de dióxido de carbono atua na inibição da desmineralização do esmalte, reduzindo sua solubilidade aos ácidos e, este efeito pode ser potencializado quando associado a agentes fluoretados. Assim, o objetivo deste trabalho foi descrever as características do laser de CO2, discutir os mecanismos de ação do laser na inibição da desmineralização do esmalte e ainda, revisar a literatura a respeito de seus efeitos quando combinado ao íon flúor

  9. Fractional CO2 laser is as effective as Q-switched ruby laser for the initial treatment of a traumatic tattoo. (United States)

    Seitz, Anna-Theresa; Grunewald, Sonja; Wagner, Justinus A; Simon, Jan C; Paasch, Uwe


    Q-switched laser treatments are considered the standard method for removing both regular and traumatic tattoos. Recently, the removal of tattoo ink using ablative fractional lasers has been reported. Ablative fractional CO2 laser and q-switched ruby laser treatments were used in a split-face mode to compare the safety and efficacy of the two types of laser in removing a traumatic tattoo caused by the explosion of a firework. A male patient suffering from a traumatic tattoo due to explosive deposits in his entire face was subjected to therapy. A series of eleven treatments were performed. The right side of the face was always treated using an ablative fractional CO2 laser, whereas the left side was treated only using a q-switched ruby laser. After a series of eleven treatments, the patient demonstrated a significant lightening on both sides of his traumatic tattoo, with no clinical difference. After the first six treatments, the patient displayed greater lightening on the right side of his face, whereas after another five treatments, the left side of the patient's face appeared lighter. No side effects were reported. In the initial stage of removing the traumatic tattoo, the ablative fractional laser treatment appeared to be as effective as the standard ruby laser therapy. However, from the 6th treatment onward, the ruby laser therapy was more effective. Although ablative fractional CO2 lasers have the potential to remove traumatic tattoos, they remain a second-line treatment option.

  10. Use of CO2 laser and AgClBr infrared transmitting fibers for tympanoplasty: experiments on animal models (United States)

    Zilker, Zeev; Daykhovsky, Leon; Nageris, Ben I.; Feinmesser, R.; Papaioannou, Thanassis; Ravid, Avi; Kariv, Naam; Katzir, Abraham


    One of the most common ear disease is Chronic Otitis Media that leads to a tympanic membrane perforation. The treatment of this condition is by a surgical procedure, tympanoplasty that is often done under local or general anesthesia. During this procedure an autologous fascia is applied to close the perforation. Commonly, fixation of the fascia is achieved mostly by Gel-Form. During the last several years various fascia fixation techniques were suggested. These included a welding procedure based on using an Argon laser. The disadvantages of the latter is that the visible Argon laser is not absorbed well by the relatively thin tympanic membrane and the fascia. It does not lead to strong weld and it may heat the middle of the ear, causing neural hearing loss. The CO2 laser IR radiation is much more suitable for welding of these thin tissues, because of its very high absorption in tissues. There is still a need to deliver this radiation to the weld site using a thin and flexible optical fiber. In this work we have welded fascia on the tympanic membranes of guinea pigs using a CO2 laser. Holes of diameter 2-3 mm were punctured in the membranes and apiece of fascia was placed on the holes. Laser power of the order of 0.5W was delivered to the fascia using an IR transmitting AgClBr fiber. In experiments done on 11 animals and CO2 laser welding was successfully done on in 15 years. The success of these preliminary studies in the animal models shows that CO2 laser tympanoplasty could be a very valuable surgical technique.

  11. Development of a laser remote sensing instrument to measure sub-aerial volcanic CO2 fluxes (United States)

    Queisser, Manuel; Burton, Mike


    A thorough quantification of volcanic CO2 fluxes would lead to an enhanced understanding of the role of volcanoes in the geological carbon cycle. This would enable a more subtle understanding of human impact on that cycle. Furthermore, variations in volcanic CO2 emissions are a key to understanding volcanic processes such as eruption phenomenology. However, measuring fluxes of volcanic CO2 is challenging as volcanic CO2 concentrations are modest compared with the ambient CO2 concentration (~400 ppm) . Volcanic CO2 quickly dilutes with the background air. For Mt. Etna (Italy), for instance, 1000 m downwind from the crater, dispersion modelling yields a signal of ~4 ppm only. It is for this reason that many magmatic CO2 concentration measurements focus on in situ techniques, such as direct sampling Giggenbach bottles, chemical sensors, IR absorption spectrometers or mass spectrometers. However, emission rates are highly variable in time and space. Point measurements fail to account for this variability. Inferring 1-D or 2-D gas concentration profiles, necessary to estimate gas fluxes, from point measurements may thus lead to erroneous flux estimations. Moreover, in situ probing is time consuming and, since many volcanoes emit toxic gases and are dangerous as mountains, may raise safety concerns. In addition, degassing is often diffuse and spatially extended, which makes a measurement approach with spatial coverage desirable. There are techniques that allow to indirectly retrieve CO2 fluxes from correlated SO2 concentrations and fluxes. However, they still rely on point measurements of CO2 and are prone to errors of SO2 fluxes due to light dilution and depend on blue sky conditions. Here, we present a new remote sensing instrument, developed with the ERC project CO2Volc, which measures 1-D column amounts of CO2 in the atmosphere with sufficient sensitivity to reveal the contribution of magmatic CO2. Based on differential absorption LIDAR (DIAL) the instrument measures

  12. Atomic hydrogen emission induced by TEA CO(2) laser bombardment on solid samples at low pressure and its analytical application. (United States)

    Idris, Nasrullah; Terai, Sumito; Lie, Tjung Jie; Kurniawan, Hendrik; Kobayashi, Takao; Maruyama, Tadashi; Kagawa, Kiichiro


    Hydrogen emission has been studied in laser plasmas by focusing a TEA CO(2) laser (10.6 microm, 500 mJ, 200 ns) on various types of samples, such as glass, quartz, black plastic sheet, and oil on copper plate sub-target. It was found that H(alpha) emission with a narrow spectral width occurs with high efficiency when the laser plasma is produced in the low-pressure region. On the contrary, the conventional well-known laser-induced breakdown spectroscopy (LIBS), which is usually carried out at atmospheric air pressure, cannot be applied to the analysis of hydrogen as an impurity. By combining low-pressure laser-induced plasma spectroscopy with laser surface cleaning, a preliminary quantitative analysis was made on zircaloy pipe samples intentionally doped with hydrogen. As a result, a good linear relationship was obtained between H(alpha) emission intensity and its concentration.

  13. CO2laser-induced bump formation and growth on polystyrene for multi-depth soft lithography molds

    KAUST Repository

    Li, Huawei


    This paper reports the process of creating bumps on the surface of polystyrene (PS) induced by a CO2laser at low powers. The paper also outlines the procedure for growing bumps induced by multiple laser scans on the aforementioned bumps. These bumps result from the net volume gain of the laser heat-affected zone on the PS rather than from a deposition process, and the expansion of the heat-affected zone on PS was verified by measuring the hardness change using nanoindentation. The bumps have a much smoother surface than microchannels fabricated with laser cutting; depending on the laser power, they have heights ranging from hundreds of nanometers to 42m. The laser scanning speed and scan times along with this technique offer a fast and low-cost alternative for fabricating molds for multi-depth PDMS microfluidic devices. © 2012 IOP Publishing Ltd.

  14. Wedge cutting of mild steel by CO 2 laser and cut-quality assessment in relation to normal cutting (United States)

    Yilbas, B. S.; Karatas, C.; Uslan, I.; Keles, O.; Usta, Y.; Yilbas, Z.; Ahsan, M.


    In some applications, laser cutting of wedge surfaces cannot be avoided in sheet metal processing and the quality of the end product defines the applicability of the laser-cutting process in such situations. In the present study, CO 2 laser cutting of the wedge surfaces as well as normal surfaces (normal to laser beam axis) is considered and the end product quality is assessed using the international standards for thermal cutting. The cut surfaces are examined by the optical microscopy and geometric features of the cut edges such as out of flatness and dross height are measured from the micrographs. A neural network is introduced to classify the striation patterns of the cut surfaces. It is found that the dross height and out of flatness are influenced significantly by the laser output power, particularly for wedge-cutting situation. Moreover, the cut quality improves at certain value of the laser power intensity.

  15. Ventilation time of the middle ear in otitis media with effusion (OME) after CO2 laser myringotomy. (United States)

    Sedlmaier, Benedikt; Jivanjee, Antonio; Gutzler, Rico; Huscher, Dörte; Jovanovic, Sergije


    The aim of this study was to investigate the transtympanic ventilation time, the healing course of the tympanic membrane, the early and late complications, and the recurrence rate of otitis media with effusion (OME) within 6 months after CO2 laser myringotomy with the CO2 laser otoscope Otoscan. Prospective clinical study. In this study, laser myringotomy was performed with the CO2 laser otoscope Otoscan in a patient population comprising 81 children (159 ears) with a history of otitis media with effusion (OME) associated with adenoidal and sometimes tonsillar hyperplasia. The procedure on the tympanic membrane was accordingly combined with an adenoidectomy, a CO2 laser tonsillotomy, or a tonsillectomy and therefore performed under insufflation anesthesia. In all ears, approximately 2 mm circular perforations were created in the lower anterior quadrants with a power of 12 to 15 W, a pulse duration of 180 msec, and a scanned area of 2.2 mm in diameter. None of the children showed postoperative impairment of cochleovestibular function such as sensorineural hearing loss or nystagmus. Otomicroscopic and videoendoscopic monitoring documented the closure time and healing pattern of tympanic membrane perforations. The mean closure time was found to be 16.35 days (minimum, 8 days; maximum, 34 days). As a rule, an onion-skin-like membrane of keratinized material was seen in the former myringotomy perforations at the time of closure. At the follow-up 6 months later, the condition of the tympanic membrane of 129 ears (81.1%) could be checked by otomicroscopy and videoendoscopy and the hearing ability by audiometry and tympanometry. The CO2 laser myringotomy sites appeared normal and irritation-free. Two of the tympanic membranes examined (1.6%) showed atrophic scar formation, and 1 (0.8%) had a perforation with a diameter of 0.3 mm. The perforation was seen closed in a control otoscopy 15 months postoperatively. OME recurred in 26.3% of the ears seen intraoperatively with

  16. Effect of Surface Treatment with Carbon Dioxide (CO2) Laser on Bond Strength between Cement Resin and Zirconia. (United States)

    Kasraei, Shahin; Atefat, Mohammad; Beheshti, Maryam; Safavi, Nassimeh; Mojtahedi, Maryam; Rezaei-Soufi, Loghman


    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. 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/cm(2). 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 resin cement and zirconia ceramic (p value = 0.001). Under the limitations of this study, surface treatment with CO2 laser increased the SBS between resin cement and the zirconia ceramic.

  17. Collective Thomson scattering based on CO2 laser for ion energy spectrum measurements in JT-60U (United States)

    Kondoh, T.; Miura, Y.; Lee, S.; Richards, R. K.; Hutchinson, D. P.; Bennett, C. A.


    A collective Thomson scattering (CTS) diagnostic system based on a pulsed CO2 laser has been developed and brought into operation to establish a measurement technique for ion temperature and the energy spectrum of fast ions. The pulsed CO2 laser (wavelength 10.6 μm, beam energy 15 J, pulse width 1 μs) and a heterodyne receiver were installed on the JT-60U tokamak. Calculation of the scattered power spectrum from high temperature plasma in JT-60U shows that a good signal-to-noise value is expected for the bulk-ion temperature measurement. Calibration of the heterodyne receiver system has been carried out using a large area (12×12 cm2) blackbody radiation source. Commissioning of the CTS system by injecting the CO2 laser into the plasmas has been accomplished. However, a scattered signal has not yet been detected due to electrical noise originating from the pulsed lasers discharge and stray signal coming from mode impurities in the pulsed laser. After the electrical and stray light reduction, ion temperature will be evaluated from the scattered spectrum using the CTS system.

  18. A small size 1-3 atm pulsed CO2 laser with series-connected spark gaps ultraviolet preionization. (United States)

    Silakhori, K; Jelvani, S; Ghanavati, F; Sajad, B; Talebi, M; Sadr, M R


    A small size pulsed CO2 laser with rounded edge flat profiled electrodes and variable gas pressure in 1-3 atm range has been constructed and characterized. The perionization system consists of a pair of 16 series-connected spark gaps located along either side of the main electrodes by which, the number of required preionization capacitors is reduced to 4. Sharpening of the main discharge has been performed using a 300 pF peaking capacitor. A maximum energy of 160 mJ/pulse was obtained for CO2:N2:He≡1:1:8 gas mixture and 33 kV discharge voltage. By increasing the laser gas pressure in 1-3 atm range, the duration of spike and tail parts of the laser pulses have been reduced from 110 ns and 4 μs to 37 ns and 1 μs, respectively.

  19. Experimental and numerical investigations on the density profile of CO2 laser-produced Sn plasma for an EUVL source (United States)

    Tao, Y.; Ueno, Y.; Yuspeh, S.; Burdt, R. A.; Amin, N.; Shaikh, N. M.; Tillack, M. S.; Najmabadi, F.


    Experimentally observed density profile of CO2 laser-produced Sn plasma was compared with that predicted by one dimensional hydrodynamic radiation numerical code. Experimental data showed a much smaller corona and a much shorter shift distance of the critical density from the initial target surface as compared with those predicted by an isothermal model and the numerical simulation. The possible reason may come from thin localized laser deposition region, less energy transport into the corona and into the dense region beyond the critical density. This research suggests that more efforts to understand the fundamental dominating the interaction of CO2 laser with high Z plasma are necessary to form a more solid foundation for the application of numerical method to the development of the EUVL source.

  20. Novel endoscopic application of a new flexible-fiber CO2 laser for esophageal mucosal ablation in a porcine model. (United States)

    Anandasabapathy, S; Maru, D; Klumpp, S; Uthamanthil, R; Borne, A; Bhutani, M S


    The CO (2) laser is a surgical tool that is widely used because of its predictable penetration depth and minimal collateral damage due to efficient absorption of CO (2) laser energy by tissue water. Until recently, endoscopic use was limited by lack of an efficient, flexible delivery system. The aim of the current study was to evaluate the performance, efficacy, and safety of a novel, photonic band-gap CO (2) laser configured for esophageal mucosal ablation. This was an endoscopic experimental study in a porcine survival model. Initial evaluation was done on ex vivo tissue followed by endoscopic studies at 7-, 10-, 15-, and 20-W power and at 0-, 1-, 2-, 5-, and 10-mm distances, using continuous and pulsed currents, to determine optimal performance settings. In an IACUC-approved protocol, six pigs underwent circumferential ablation of the distal 6 cm of the esophagus at 10W continuous current. The animals were monitored for 2 or 4 weeks to evaluate delayed effects. Prior to euthanasia, the proximal esophagus was ablated to evaluate the homogeneity of ablation and depth of injury immediately after single and repeat ablation. The animals resumed normal diets within 24 hours and experienced no dysphagia or weight loss. Pathology at 2 and 4 weeks revealed complete re-epithelialization with minimal histologic injury. A single application of the laser produced complete transepithelial ablation of a mean of 83.3 % of the surface area (range 55 % - 100 %); depth of injury was to the muscularis mucosa in five pigs and to the superficial submucosa in one pig. With ablation, sloughing, and re-ablation, a mean of 95 % transepithelial ablation was achieved (range 80 % -100 %) with similar depth of injury. Using a novel, flexible CO (2) laser, homogeneous ablation was achieved with predictable penetration and minimal deep tissue injury. These results warrant further evaluation of the laser in Barrett's esophagus, as it may overcome the limitations of current technologies

  1. Effect of CO2 and Nd:YAG Lasers on Shear Bond Strength of Resin Cement to Zirconia Ceramic (United States)

    Kasraei, Shahin; Yarmohamadi, Ebrahim; Shabani, Amanj


    Objectives: Because of poor bond between resin cement and zirconia ceramics, laser surface treatments have been suggested to improve adhesion. The present study evaluated the effect of CO2 and Nd:YAG lasers on the shear bond strength (SBS) of resin cement to zirconia ceramic. Materials and Methods: Ninety zirconia disks (6×2 mm) were randomly divided into six groups of 15. In the control group, no surface treatment was used. In the test groups, laser surface treatment was accomplished using CO2 and Nd:YAG lasers, respectively (groups two and three). Composite resin disks (3×2 mm) were fabricated and cemented to zirconia disks with self-etch resin cement and stored in distilled water for 24 hours. In the test groups four-six, the samples were prepared as in groups one-three and then thermocycled and stored in distilled water for six months. The SBS tests were performed (strain rate of 0.5 mm/min). The fracture modes were observed via stereomicroscopy. Data were analyzed with one and two-way ANOVA, independent t and Tukey’s tests. Results: The SBS values of Nd:YAG group (18.95±3.46MPa) was significantly higher than that of the CO2 group (14.00±1.96MPa), but lower than that of controls (23.35±3.12MPa). After thermocycling and six months of water storage, the SBS of the untreated group (1.80±1.23 MPa) was significantly lower than that of the laser groups. In groups stored for 24 hours, 60% of the failures were adhesive; however, after thermocycling and six months of water storage, 100% of failures were adhesive. Conclusion: Bonding durability of resin cement to zirconia improved with CO2 and Nd:YAG laser surface treatment of zirconia ceramic. PMID:27148380

  2. All-fiber versatile laser frequency reference at 2 μm for CO2 space-borne lidar applications (United States)

    Schilt, Stéphane; Matthey, Renaud; Hey Tow, Kenny; Thévenaz, Luc; Südmeyer, Thomas


    We present a frequency stabilized laser at 2051 nm based on a versatile all-fibered stabilization setup. A modulation sideband locking technique is implemented to lock the laser at a controlled frequency detuning from the center of the CO2 R(30) transition envisaged for space-borne differential absorption lidar (DIAL) applications. This method relies on the use of a compact all-fibered gas reference cell that makes the setup robust and immune to mechanically induced optical misalignments. The gas cell is fabricated using a hollow-core photonic crystal fiber filled with pure CO2 at a low pressure of 20 mbar and hermetically sealed at both ends by splices to silica fibers. Different configurations of this fibered cell have been developed and are presented. With this technique, frequency stabilities below 40 kHz at 1-s integration time and <100 kHz up to 1000-s averaging time were achieved for a laser detuning by around 1 GHz from the center of the CO2 transition. These stabilities are compliant with typical requirements for the reference seed source for a space CO2 DIAL.

  3. CO2-laser micromachining and back-end processing for rapid production of PMMA-based microfluidic systems

    DEFF Research Database (Denmark)

    Klank, Henning; Kutter, Jörg Peter; Geschke, Oliver


    In this article, we focus on the enormous potential of a CO2-laser system for rapidly producing polymer microfluidic structures. The dependence was assessed of the depth and width of laser-cut channels on the laser beam power and on the number of passes of the beam along the same channel. In the ......In this article, we focus on the enormous potential of a CO2-laser system for rapidly producing polymer microfluidic structures. The dependence was assessed of the depth and width of laser-cut channels on the laser beam power and on the number of passes of the beam along the same channel....... In the experiments the laser beam power was varied between 0 and 40 W and the passes were varied in the range of 1 to 7 times. Typical channel depths were between 100 and 300 m m, while the channels were typically 250 m m wide. The narrowest produced channel was 85 m m wide. Several bonding methods...


    Directory of Open Access Journals (Sweden)

    Mircea UDREA


    Full Text Available Preliminary results obtained in developing a visualisation technique for non-invasive analysis of air flow inside INCAS subsonic wind tunnel and its appendages are presented. The visualisation technique is based on using a green light sheet generated by a continuous wave (cw longitudinally diode pumped and frequency doubled Nd:YAG laser. The output laser beam is expanded on one direction and collimated on rectangular direction. The system is tailored to the requirements of qualitative analysis and vortex tracking requirements inside the INCAS 2.5m x 2.0m subsonic wind tunnel test section, for measurements performed on aircraft models. Also the developed laser techniques is used for non-invasive air flow field analysis into environmental facilities settling room (air flow calming area. Quantitative analysis is enabled using special image processing tools upon movies and pictures obtained during the experiments. The basic experimental layout in the wind tunnel takes advantage of information obtained from the investigation of various aircraft models using the developed visualisation technique. These results are further developed using a Particle Imaging Velocimetry (PIV experimental technique.The focus is on visualisation techniques to be used for wind flow characterization at different altitudes in indus-trial and civil buildings areas using a light sheet generated by a Nd:YAG cw pumped and doubled laser at 532 nm wave-length. The results are important for prevention of biological/chemical disasters such as spreading of extremely toxic pol-lutants due to wind. Numerical simulations of wind flow and experimental visualisation results are compared. A good agreement between these results is observed.

  5. Rotationally resolved IR-diode laser studies of ground-state CO2 excited by collisions with vibrationally excited pyridine. (United States)

    Johnson, Jeremy A; Kim, Kilyoung; Mayhew, Maurine; Mitchell, Deborah G; Sevy, Eric T


    Relaxation of highly vibrationally excited pyridine (C5NH5) by collisions with carbon dioxide has been investigated using diode laser transient absorption spectroscopy. Vibrationally hot pyridine (E' = 40,660 cm(-1)) was prepared by 248 nm excimer laser excitation followed by rapid radiationless relaxation to the ground electronic state. Pyridine then collides with CO2, populating the high rotational CO2 states with large amounts of translational energy. The CO2 nascent rotational population distribution of the high-J (J = 58-80) tail of the 00(0)0 state was probed at short times following the excimer laser pulse to measure rate constants and probabilities for collisions populating these CO2 rotational states. Doppler spectroscopy was used to measure the CO2 recoil velocity distribution for J = 58-80 of the 00(0)0 state. The energy-transfer distribution function, P(E,E'), from E' - E approximately 1300-7000 cm(-1) was obtained by re-sorting the state-indexed energy-transfer probabilities as a function of DeltaE. P(E,E') is fit to an exponential or biexponential function to determine the average energy transferred in a single collision between pyridine and CO2. Also obtained are fit parameters that can be compared to previously studied systems (pyrazine, C6F6, methylpyrazine, and pyrimidine/CO2). Although the rotational and translational temperatures that describe pyridine/CO2 energy transfer are similar to previous systems, the energy-transfer probabilities are much smaller. P(E,E') fit parameters for pyridine/CO2 and the four previously studied systems are compared to various donor molecular properties. Finally, P(E,E') is analyzed in the context of two models, one indicating that P(E,E') shape is primarily determined by the low-frequency out-of-plane donor vibrational modes, and the other that indicates that P(E,E') shape can be determined from how the donor molecule final density of states changes with DeltaE.



    Fontaine, B.; Forestier, B.; Gross, P.; Koudriavtsev, E.


    High power long pulse infrared laser emission has been achieved on CO2 molecule with the high density and very low temperature supersonic flow-electron beam-stabilized discharge excitation device developped at I.M.F.M. ([MATH] [MATH] 2 amagats, T [MATH] 70 - 150 K). Laser emission at [MATH] = 10.6 µ has been achieved for a resonant cavity set at the discharge location and also 3 cm downstream of the discharge location. With Ar/CO2, Ar/CO2/H2, He/CO2, and He/CO2/N2 mixtures, lasing energy and ...

  7. Numerical simulation and experimental investigation of Ti-6Al-4V melted by CW fiber laser at different pressures (United States)

    Tabassum, Aasma; Zhou, Jie; Han, Bing; Ni, Xiao-wu; Sardar, Maryam


    The interaction of continuous wave (CW) fiber laser with Ti-6Al-4V alloy is investigated numerically and experimentally at different laser fluence values and ambient pressures of N2 atmosphere to determine the melting time threshold of Ti-6Al-4V alloy. A 2D-axisymmetric numerical model considering heat transfer and laminar flow is established to describe the melting process. The simulation results indicate that material melts earlier at lower pressure (8.0 Pa) than at higher pressure (8.8×104 Pa) in several milliseconds with the same laser fluence. The experimental results demonstrate that the melting time threshold at high laser fluence (above 1.89×108 W/m2) is shorter for lower pressure (vacuum), which is consistent with the simulation. While the melting time threshold at low laser fluence (below 1.89×108 W/m2) is shorter for higher pressure. The possible aspects which can affect the melting process include the increased heat loss induced by the heat conduction between the metal surface and the ambient gas with the increased pressure, and the absorption variation of the coarse surface resulted from the chemical reaction.

  8. Single photon ionization of van der Waals clusters with a soft x-ray laser: (CO2)n and (CO2)n(H2O)m. (United States)

    Heinbuch, S; Dong, F; Rocca, J J; Bernstein, E R


    Pure neutral (CO2)n clusters and mixed (CO2)n(H2O)m clusters are investigated employing time of flight mass spectroscopy and single photon ionization at 26.5 eV. The distribution of pure (CO2)n clusters decreases roughly exponentially with increasing cluster size. During the ionization process, neutral clusters suffer little fragmentation because almost all excess cluster energy above the vertical ionization energy is taken away by the photoelectron and only a small part of the photon energy is deposited into the (CO2)n cluster. Metastable dissociation rate constants of (CO2)n+ are measured in the range of (0.2-1.5) x 10(4) s(-1) for cluster sizes of 5CO2-H2O clusters are studied under different generation conditions (5% and 20% CO2 partial pressures and high and low expansion pressures). At high CO2 concentration, predominant signals in the mass spectrum are the (CO2)n+ cluster ions. The unprotonated cluster ion series (CO2)nH2O+ and (CO2)n(H2O)2+ are also observed under these conditions. At low CO2 concentration, protonated cluster ions (H2O)nH+ are the dominant signals, and the protonated CO2(H2O)nH+ and unprotonated (H2O)n+ and (CO2)(H2O)n+ cluster ion series are also observed. The mechanisms and dynamics of the formation of these neutral and ionic clusters are discussed.

  9. Novel packaging for CW and QCW diode laser modules for operation with high power and duty cycles (United States)

    Fassbender, Wilhelm; Lotz, Jens; Kissel, Heiko; Biesenbach, Jens


    Continuous wave (CW) and quasi-continuous wave (QCW) operated diode laser bars and arrays have found a wide range of industrial, medical, scientific, military and space applications with a broad variety in wavelength, pulse energy, pulse duration and beam quality. Recent applications require even higher power, duty cycles and power density. The heat loss will be dissipated by conductive cooling or liquid cooling close to the bars. We present the latest performance and reliability data of two novel high-brightness CW and QCW arrays of customized and mass-production modules, in compact and robust industry design for operation with high power and high duty cycles. All designs are based on single diode packages consisting of 10mm laser bars, soft or hard soldered between expansion matched submounts. The modular components cover a wide span of designs which differ basically in water/conduction (active/passive) cooled, single, linear (horizontal and vertical) arranged designs, as well as housed and unhoused modules. The different assembling technologies of active and passive cooled base plates affect the heat dissipation and therefore the reachable power at different QCW operating conditions, as well as the lifetime. As an example, a package consisting of 8 laser diodes, connected to a 28.8*13.5*7.0mm3 DCB (direct copper bonded) submount, passively or actively cooled is considered. This design is of particular interest for mobile applications seamless module to module building system, with an infinite number of laser bars at 1.7mm pitch. Using 940nm bars we can reach an optical output power per bar of 450W at 25°C base plate temperature with 10Hz, 1.2% duty cycle and 1.2ms pulse duration. As an additional example, micro channel coolers can be vertically stacked up to 50 diodes with a 1,15mm pitch. This design is suitable for all applications, demanding also compactness and light weight and high power density. Using near infrared bars and others, we can reach an optical

  10. Effects of CO2 laser irradiation on matrix-rich biofilm development formation–an in vitro study

    Directory of Open Access Journals (Sweden)

    Bruna Raquel Zancopé


    Full Text Available Background A carbon dioxide (CO2 laser has been used to morphologically and chemically modify the dental enamel surface as well as to make it more resistant to demineralization. Despite a variety of experiments demonstrating the inhibitory effect of a CO2 laser in reduce enamel demineralization, little is known about the effect of surface irradiated on bacterial growth. Thus, this in vitro study was preformed to evaluate the biofilm formation on enamel previously irradiated with a CO2 laser (λ = 10.6 µM. Methods For this in vitro study, 96 specimens of bovine enamel were employed, which were divided into two groups (n = 48: 1 Control-non-irradiated surface and 2 Irradiated enamel surface. Biofilms were grown on the enamel specimens by one, three and five days under intermittent cariogenic condition in the irradiated and non-irradiated surface. In each assessment time, the biofilm were evaluated by dry weigh, counting the number of viable colonies and, in fifth day, were evaluated by polysaccharides analysis, quantitative real time Polymerase Chain Reaction (PCR as well as by contact angle. In addition, the morphology of biofilms was characterized by fluorescence microscopy and field emission scanning electron microscopy (FESEM. Initially, the assumptions of equal variances and normal distribution of errors were conferred and the results are analyzed statistically by t-test and Mann Whitney test. Results The mean of log CFU/mL obtained for the one-day biofilm evaluation showed that there is statistical difference between the experimental groups. When biofilms were exposed to the CO2 laser, CFU/mL and CFU/dry weight in three day was reduced significantly compared with control group. The difference in the genes expression (Glucosyltransferases (gtfB and Glucan-binding protein (gbpB and polysaccharides was not statically significant. Contact angle was increased relative to control when the surface was irradiated with the CO2 laser. Similar

  11. Enhancing hair growth in male androgenetic alopecia by a combination of fractional CO2 laser therapy and hair growth factors. (United States)

    Huang, Yue; Zhuo, Fenglin; Li, Linfeng


    Laser therapy and growth factors have been used as alternative treatments for male androgenetic alopecia (MAA). The aim of this study is to determine the efficacy and safety of hair growth factors alone or combined with ablative carbon dioxide (CO 2 ) fractional laser therapy in MAA. Twenty-eight men were enrolled in this randomized half-split study based on a left-head to right-head pattern. Fractional CO 2 laser treatment was unilaterally performed; hair growth factors were bilaterally applied. Six sessions with 2-week intervals were performed. Global photographs and dermoscopy assessments were performed at the baseline and 4 months after first treatment. Global photographs underwent blinded review by three independent dermatologists. Scanning electron microscopy was used to compare changes in hair-follicle phase and hair-shaft diameter. Twenty-seven participants completed the 4-month treatment schedule. One patient was lost. Mean hair density increased from 114 ± 27 to 143 ± 25/cm 2 (P hair follicles appeared to transition from telogen to anagen, and hair-shaft diameter increased in five randomly selected patients. Ablative fractional CO 2 laser combined with hair growth factors may serve as an alternative treatment for MAA in individuals unwilling/unable to undergo medical or surgical treatment.

  12. Theoretical estimation and experimental studies on gas dissociation in TEA CO2 laser for long term arc free operation (United States)

    Kumar, Manoj; Biswas, A. K.; Bhargav, Pankaj; Reghu, T.; Sahu, Shashikiran; Pakhare, J. S.; Bhagat, M. S.; Kukreja, L. M.


    Gas dissociation in a high energy, high repetition rate Transversely Excited Atmospheric (TEA) CO2 laser in both sealed-off and gas replenishment modes were studied for nitrogen lean gas mixture. A comprehensive theoretical model based on the Boltzmann transport equation and the discharge excitation circuit equations was adopted to calculate the amount of CO2 dissociated during a single discharge pulse. Theoretically it is shown that inclusion of superelastic collisions in the Boltzmann transport equation is necessary for precise estimation of dissociation per pulse, particularly at high discharge energy loadings and for nitrogen rich gas mixtures. Gas lifetime for repetitively pulsed operations was found experimentally by measuring the amount of CO formed when frequent arcing sets in under sealed off operation. Using this model, the optimum replenishment rate of CO2 either by gas purging and/or by catalytic regeneration needed for arc free long term operation of the laser was estimated. The measured saturation values of CO concentration in the laser chamber agreed well with the calculated values for various operating conditions. Arc free, long term repetitively pulsed operation of the laser was achieved in the gas replenishment mode with gas purging and/or catalytic regeneration.

  13. Comparison of Q-switched Nd:YAG laser alone versus its combination with ultrapulse CO2 laser for the treatment of black tattoo. (United States)

    Vanarase, Mithila; Gautam, Ram Krishan; Arora, Pooja; Bajaj, Sonali; Meena, Neha; Khurana, Ananta


    Q-switched lasers are conventionally used for the treatment of black tattoo. However, they require multiple sittings, and the response may be slow due to competing epidermal pigment in dark skin. To compare the efficacy of Q-switched Nd:YAG laser alone with its combination with ultrapulse CO 2 for the removal of black tattoo. Sixty patients with black tattoo were randomized into two groups viz., group A and group B. Group A was treated with QS Nd:YAG laser (1064 nm) alone, and group B received combination of ablative ultrapulse CO 2 followed by fixed-dose QS Nd:YAG laser (1064 nm), at 6-week interval for a maximum of 6 sittings. After each sitting, 3 independent physicians noted percentage of improvement that was evaluated using visual analogue scale (VAS) and grading system for tattoo ink lightening (TIL). Combination laser (group B) showed statistically significant improvement in mean VAS score in the last 2 noted visits as compared to 1st session (p tattoos, combination of ultrapulse CO 2 laser and QS Nd:YAG laser is superior to QS Nd:YAG laser alone.

  14. Caries inhibition with a CO2 9.3 μm laser: An in vitro study. (United States)

    Rechmann, Peter; Rechmann, Beate M T; Groves, William H; Le, Charles Q; Rapozo-Hilo, Marcia L; Kinsel, Richard; Featherstone, John D B


    The caries preventive effects of different laser wavelengths have been studied in the laboratory as well as in pilot clinical trials. The objective of this in vitro study was to evaluate whether irradiation with a new 9.3 μm microsecond short-pulsed CO2 -laser could enhance enamel caries resistance with and without additional fluoride applications. One hundred and one human tooth enamel samples were divided into seven groups. Each group was treated with different laser parameters (CO2 -laser, wavelength 9.3 μm, 43 Hz pulse-repetition rate, pulse duration between 3 µs at 1.5 mJ/pulse to 7 µs at 2.9 mJ/pulse). A laboratory pH-cycling model followed by cross-sectional microhardness testing determined the mean relative mineral loss delta Z (ΔZ) for each group to assess caries inhibition in tooth enamel by the CO2 9.3 µm short-pulsed laser irradiation. The pH-cycling was performed with or without additional fluoride. The non-laser control groups with additional fluoride had a relative mineral loss (ΔZ, vol% × µm) that ranged between 646 ± 215 and 773 ± 223 (mean ± SD). The laser irradiated and fluoride treated samples had a mean ΔZ ranging between 209 ± 133 and 403 ± 245 for an average 55% ± 9% reduction in mineral loss (ANOVA test, P laser treated controls without additional fluoride. In contrast, the laser treated groups without additional fluoride showed a ΔZ between 470 ± 240 and 669 ± 209 (ANOVA test, P laser energy renders enamel caries resistant with and without additional fluoride use. The observed enhanced acid resistance occurred with the laser irradiation parameters used without obvious melting of the enamel surface as well as after irradiation with energies causing cutting of the enamel. Lasers Surg. Med. 48:546-554, 2016. Published 2016. This article is a U.S. Government work and is in the public domain in the USA. Published 2016. This article is a U.S. Government work and is in the

  15. High Power CW Operation of a Hole-Outcoupled Free-Electron Laser

    CERN Document Server

    Shinn, M D; Benson, S V; Gould, C W; Gubeli, J G; Hardy, D; Neil, G; Zhang, S


    In order to provide widely-tunable light to our users, we used a hole outcoupler. To date, we've produced 85 W at 2.8 microns, and been able to continuously tune over a 1 micron spectral range. Besides the anticipated low outcoupling efficiency associated with this scheme, we found that we had considerable problems stabilizing the output when we operated our FEL in cw mode. We believe that this is due to the long time available for mode competition to develop. Measurements of gain, loss, and transverse mode profiles (both intracavity and output) will be compared with our models.

  16. Automatic Optimization of Focal Point Position in CO2 Laser Welding with Neural Network in A Focus Control System

    DEFF Research Database (Denmark)

    Gong, Hui; Olsen, Flemming Ove

    CO2 lasers are increasingly being utilized for quality welding in production. Considering the high cost of equipment, the start-up time and the set-up time should be minimized. Ideally the parameters should be set up and optimized more or less automatically. In this paper a control system...... is designed and built to automatically optimize the focal point position, one of the most important parameters in CO2 laser welding, in order to perform a desired deep/full penetration welding. The control system mainly consists of a multi-axis motion controller - PMAC, a light sensor - Photo Diode, a data...... acquisition card - DAQCard-700, and a self-learning mechanism - Neural Network. The optimization procedure starts with the welding process being carried out by continuously moving the focal point position from above a welding plate to below the plate, thus the process is ensured to be shifted from initially...

  17. Efeitos do Laser de Dióxido de Carbono (CO2) no esmalte dentário


    Karlla Almeida Vieira


    Resumo: A irradiação do esmalte dentário com o laser de Dióxido de Carbono (CO2) modifica a superfície deste substrato e traz benefícios no que diz respeito a um aumento na resistência aos ácidos quando ocorre um desafio cariogênico. Sendo assim, esta tese constituída por 2 artigos, teve os seguintes objetivos: (1) revisar sistematicamente o efeito da irradiação do esmalte (mudanças morfológicas e de composição) pelo laser de CO2 com comprimento de onda 10,6 µm e sua resistência a desminerali...

  18. High energy 2-micron solid-state laser transmitter for NASA's airborne CO2 measurements (United States)

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


    A 2-micron pulsed, Integrated Path Differential Absorption (IPDA) lidar instrument for ground and airborne atmospheric CO2 concentration measurements via direct detection method is being developed at NASA Langley Research Center. This instrument will provide an alternate approach to measure atmospheric CO2 concentrations with significant advantages. A high energy pulsed approach provides high precision measurement capability by having high signal-to-noise level and unambiguously eliminates the contamination from aerosols and clouds that can bias the IPDA measurement.

  19. Research on atmospheric CO2 remote sensing with open-path tunable diode laser absorption spectroscopy and comparison methods (United States)

    Xin, Fengxin; Guo, Jinjia; Sun, Jiayun; Li, Jie; Zhao, Chaofang; Liu, Zhishen


    An open-path atmospheric CO2 measurement system was built based on tunable diode laser absorption spectroscopy (TDLAS). The CO2 absorption line near 2 μm was selected, measuring the atmospheric CO2 with direct absorption spectroscopy and carrying on the comparative experiment with multipoint measuring instruments of the open-path. The detection limit of the TDLAS system is 1.94×10-6. The calibration experiment of three AZ-7752 handheld CO2 measuring instruments was carried out with the Los Gatos Research gas analyzer. The consistency of the results was good, and the handheld instrument could be used in the TDLAS system after numerical calibration. With the contrast of three AZ-7752 and their averages, the correlation coefficients are 0.8828, 0.9004, 0.9079, and 0.9393 respectively, which shows that the open-path TDLAS has the best correlation with the average of three AZ-7752 and measures the concentration of atmospheric CO2 accurately. Multipoint measurement provides a convenient comparative method for open-path TDLAS.

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

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


    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.

  1. Safety and long-term efficacy of fractional CO2 laser treatment in women suffering from genitourinary syndrome of menopause. (United States)

    Behnia-Willison, Fariba; Sarraf, Sara; Miller, Joseph; Mohamadi, Behrang; Care, Alison S; Lam, Alan; Willison, Nadia; Behnia, Leila; Salvatore, Stefano


    To evaluate the safety and long-term efficacy of fractional CO 2 laser treatment in reducing the severity of symptoms of genitourinary syndrome of menopause (GSM) in menopausal women. 102 women presenting with symptomatic GSM were treated with the fractional CO 2 laser (MonaLisa Touch, DEKA) system across a series of treatments delivered at intervals of six or more weeks. The Australian Pelvic Floor Questionnaire was used to gather data on sexual function and side-effects at three time-points across the study period (prospective panel design study). Wilcoxon signed-rank tests were used to detect statistically and clinically significant changes in sexual function and side-effects occurring from pre- to post-treatment. The primary outcome of this study was an improvement of the symptoms of GSM. The secondary outcome included bladder function and prolapse symptoms. A total of 102 women suffering from moderate to severe GSM were recruited. Eighty-four percent experienced significant improvement in their symptoms after CO 2 laser treatment. Scores on measures of sexual function, dyspareunia, and bothersomeness of sexual issues were improved from pre-treatment to long-term (12-24 month) follow-up. Furthermore, there were improvements on measures of bladder function (P=0.001), prolapse (P=0.001), vaginal sensation (P=0.001), vaginal lubrication (P<0.001) and urge incontinence (P=0.003) from the pre-treatment assessment to the second assessment (i.e. after the third treatment). In this study, fractional microablative CO 2 laser treatment was associated with an improvement in symptoms of GSM and sexual function. Copyright © 2017. Published by Elsevier B.V.

  2. Wettability characteristics of carbon steel modified with CO2, Nd:YAG, Excimer and high power diode lasers


    Lawrence, Jonathan; Li, Lin


    Interaction of CO2, Nd:YAG, excimer and high power diode laser (HPDL) radiation with the surface of a common mild steel (EN8) was found to effect changes in the wettability characteristics of the steel, namely changes in the measured contact angle. These modifications are related to changes in the surface roughness, changes in the surface oxygen content and changes in the surface energy of the mild steel. The wettability characteristics of the selected mild steel could be controll...

  3. 980-nm 14-pin butterfly module dual-channel CW QW semiconductor laser for pumping (United States)

    Deng, Yun; Yan, Changling; Qu, Yi; Li, Hui; Wang, Yuxia; Gao, Xin; Qiao, Zhongliang; Li, Mei; Qu, Bowen; Lu, Peng; Bo, Baoxue


    Nowadays, with its mature progress, the 790 nm - 1000 nm wavelength semiconductor laser is widely used in the fields of laser machining, laser ranging, laser radar, laser imaging, laser anti-counterfeit, biomedical and etc. Best of all, the 980 nm wavelength laser has its widespread application in the pumping source of Er3+ -doped fiber amplifier, optic fiber gyroscopes and other devices. The output wavelength of the fiber amplifier which takes the 980 nm wavelength laser as its pumping source is between 1060 nm and 1550 nm. This type of laser has its extremely wide range of applications in optical communication and other fields. Moreover, some new application domains keep constantly being developed. The semiconductor laser with the dual-channel ridge wave guide and the 980 nm emission wavelength is presented in this paper. In our work, we fabricated Lasers with the using of multi-quantum well (MQW) wafer grew by MBE, and the PL-wavelength of the MQW was 970 nm. The standard photofabrication method and the inductively coupled plasma (ICP) etching technology are adopted in the process of making dual-channel ridge wave guide with the width of 4 μm and height of 830 nm. In the state of continuous work at room temperature, the laser could output the single mode beam of 70 mW stably under the current of 100 mA. The threshold current of the laser diode is 17 mA and the slope efficiency is 0.89 W/A. The 3 dB spectrum bandwidth of the laser beam is 0.2 nm. This laser outputs its beam by a pigtail fiber on which Bragg grating for frequency stabilization is carved. The laser diode, the tail fiber, and the built-in refrigeration and monitoring modules are sealed in a 14-pin butterfly packaging. It can be used directly as the pumping source of Er3+ - doped fiber amplifier or optic fiber gyroscopes.

  4. In-vivo occlusal caries prevention by pulsed CO2 -laser and fluoride varnish treatment--a clinical pilot study. (United States)

    Rechmann, Peter; Charland, Daniel A; Rechmann, Beate M T; Le, Charles Q; Featherstone, John D B


    High caries prevalence in occlusal pits and fissures warrants novel prevention methods. An 86% reduction in dental enamel smooth surface demineralization in-vivo following short-pulsed 9.6 µm-CO(2) -laser irradiation was recently reported. The objective of this study was to conduct a blinded 12-month-pilot clinical trial of occlusal pit and fissure caries inhibition using the same CO(2) -laser irradiation conditions. Twenty subjects, average age 14 years, were recruited. At baseline, second molars were randomized into test and control groups, assessed by International Caries Detection & Assessment System (ICDAS-II), SOPROLIFE light-induced fluorescence evaluator in daylight and blue-fluorescence mode and DIAGNOdent. An independent investigator irradiated test molars with a CO(2) -laser, wavelength 9.6 µm, pulse-duration 20 µs, pulse-repetition-rate 20 Hz, beam diameter 800 µm, average fluence 4.5 ± 0.5 J/cm(2), 20 laser pulses per spot. At 3-, 6- and 12-month recall teeth were assessed by ICDAS, SOPROLIFE and DIAGNOdent. All subjects received fluoride varnish applications at baseline and 6-month recall. All subjects completed the 3-month, 19 the 6-month and 16 the 12-month recall. At all recalls average ICDAS scores had decreased for the test and increased for the control fissures (laser vs. control, 3-month: -0.10 ± 0.14, 0.30 ± 0.18, P > 0.05; 6-month: -0.26 ± 0.13, 0.47 ± 0.16, P = 0.001; 12-month: -0.31 ± 0.15, 0.75 ± 0.17, P laser vs. control, 6-month: 0.22 ± 0.13, 0.17 ± 0.09, P = 0.02; 12-month: 0.28 ± 0.19, 0.25 ± 0.17, P = 0.03). For SOPROLIFE blue-fluorescence evaluation mean changes in comparison to baseline for the control and the laser treated teeth were also statistically significant for the 6- and 12-month recall. Specific microsecond short-pulsed 9.6 µm CO(2) -laser irradiation markedly inhibits caries progression in pits and fissures in comparison to

  5. Measurement of the uniaxial elasticity of oral mucosa in vivo after CO2-laser evaporation and surgical excision. (United States)

    Roodenburg, J L; ten Bosch, J J; Borsboom, P C


    The stress-strain relation of oral mucosa of dogs was measured before and 6 weeks after surgical removal of mucosa. Both CO2-laser evaporation and excision were employed. Measurements were done with a miniature tensile tester, especially developed for this purpose. The load-strain ratio of the healed mucosa was proportional to the histologically determined thickness of the healed epithelium and scar tissue together. Laser evaporation caused a 75% increase, excision almost a threefold increase of the load-strain ratio compared with untreated tissue.

  6. Propulsion of a flat tin target with pulsed CO2 laser radiation: measurements using a ballistic pendulum (United States)

    Lakatosh, B. V.; Abramenko, D. B.; Ivanov, V. V.; Medvedev, V. V.; Krivtsun, V. M.; Koshelev, K. N.; Yakunin, A. M.


    The recoil momentum transfer produced by irradiation of a flat tin (Sn) target with pulses of high-power CO2 laser with intensity ranging from 107 to 1010 W cm-2 has been studied. Momentum measurements were performed using a ballistic pendulum, capable of measuring momenta as small as 0.001 g · cm s-1 . It has been established that the recoil momentum monotonically increases with the laser energy and asymptotically reaches the power scaling law p ∼ Iα with α = 0.96 +/- 0.07 . Results are compared with previously published theoretical studies.

  7. 3D finite element model for writing long-period fiber gratings by CO2 laser radiation. (United States)

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


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

  8. 3D Finite Element Model for Writing Long-Period Fiber Gratings by CO2 Laser Radiation

    Directory of Open Access Journals (Sweden)

    José Rebordão


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

  9. Deuterium separation at high pressure by nanosecond CO2 laser multiple-photon dissociation (United States)

    Marling, Jack B.; Herman, Irving P.; Thomas, Scott J.


    Photochemical deuterium separation is evaluated at pressures up to 1 atm using 2 ns duration CO2 laser pulses to achieve multiple-photon dissociation (MPD) as the isotopic separation step. Photochemical performance is compared for Freon 123 (2,2-dichloro-1,1,1-trifluoroethane), difluoromethane, and trifluoromethane based on deuterium optical selectivity in absorption, photoproduct yield, and single-step deuterium enrichment factor. The absorption coefficient versus energy fluence is measured from 0.01 to 3 J/cm2 fluence for CF3CDCl2, CDF3, and CHDF2; added buffer gas results in an order-of-magnitude increase in the CDF3 absorption coefficient. The deuterium optical selectivity in absorption at 0.5 J/cm2 fluence with added buffer is 80 for CF3CDCl2 at 10.65 μ, 800 for CHDF2 at 10.48 μ, and 2500 for CDF3 at 10.21 μ. The absorption coefficients and hence optical isotopic selectivities are dependent on fluence, and the optical selectivity attains a maximum value of 8000 for CDF3 below 0.01 J/cm2 fluence. The deuterium-bearing MPD photoproducts at high pressure are trifluoroethylene for Freon 123, hydrogen fluoride for trifluoromethane, and both hydrogen fluoride and monofluoroacetylene for difluoromethane. Yield data determined by gas chromatography are analyzed using a model describing MPD due to a focused Gaussian beam in an absorbing medium to remove compositional and geometrical effects; this analysis results in a saturation fluence (at which the dissociation probability approaches 100%) of 12±2 J/cm2 for CF3CDCl2, 20±2 J/cm2 for CDF3 buffered by 1 atm argon, 30±2 J/cm2 for CDF3 buffered by 60-400 Torr CHF3, and 22±3 J/cm2 for CHDF2 buffered by 100-400 Torr CH2F2. Near unity dissociation probabilities are obtained for samples unbuffered by argon with operating pressures up to 40 Torr for Freon 123, and up to 400 Torr for both difluoromethane and trifluoromethane; the methane derivatives are much more resistant to high pressure collisional quenching than

  10. Influence of shielding gas pressure on welding characteristics in CO2 laser-MIG hybrid welding process (United States)

    Chen, Yanbin; Lei, Zhenglong; Li, Liqun; Wu, Lin


    The droplet transfer behavior and weld characteristics have been investigated under different pressures of shielding gas in CO2 laser and metal inert/active gas (laser-MIG) hybrid welding process. The experimental results indicate that the inherent droplet transfer frequency and stable welding range of conventional MIG arc are changed due to the interaction between CO2 laser beam and MIG arc in laser-MIG hybrid welding process, and the shielding gas pressure has a crucial effect on welding characteristics. When the pressure of shielding gas is low in comparison with MIG welding, the frequency of droplet transfer decreases, and the droplet transfer becomes unstable in laser-MIG hybrid welding. So the penetration depth decreases, which shows the characteristic of unstable hybrid welding. However, when the pressure of shielding gas increases to a critical value, the hybrid welding characteristic is changed from unstable hybrid welding to stable hybrid welding, and the frequency of droplet transfer and the penetration depth increase significantly.

  11. Evaluation of Er:YAG, CO2, and Nd:YAG lasers on apical dentine permeability after apicoectomies (United States)

    Careli de Castro, Fabiana; Gariba Silva, Ricardo; Marchesan, Melissa A.; Zanin, Fatima; Brugnera, Aldo, Jr.; Pecora, Jesus D.


    Apicoectomy is a surgical procedure that consists of radicular apex resection, eliminating periapical lesion. This study evaluated the effect of CO2 and Nd:YAG lasers on root dentine permeability after apicoectomy with Er:YAG laser. Forty-four single-rooted teeth, obtained from the Endodontic Laboratory stock from the Faculty of Dentistry of Ribeirao Preto, University of Sao Paulo, were used. The teeth were instrumented with the step-back technique, irrigated with 1.0% sodium hypochlorite and sealed with Sealer 26 (Dentsply, Brazil; lateral condensation. The samples were divided into four groups of 11 teeth each that had the root sectioned 2mm from the apex: G1 - roots were sectioned with a 4138 diamond bur with cooling; G2 - roots were sectioned with pulsed Er:YAG laser at the following parameters: 15 Hz and 250 mJ; G3 - roots were sectioned with pulsed Er:YAG laser and Nd:YAG laser (10 Hz, 100 mJ, and 1 W) was app0lied on the sectioned surface; G4 - roots were sectioned with pulsed Er:YAG laser and CO2 laser (5 W, 10 seconds ON and 20 seconds OFF) was applied to the sectioned surface. The teeth were then impermeabilized with cyanoacrylate and placed in 0.5% methylene blue for 7 days. The proximal surface of the samples was removed for exposure of the sealed root canal and dye penetration was measured by means of microscopic evaluation. The results showed a statistically significant difference at the level of 1%. We conclude that all treatments presented microleakage and can placed in increasing order: Er:YAG (G2), Bur (G1), Er:YAG + Nd:YAG (G3); Er:YAG laser presented the lowest microleakage values, showing its viability for clinical use in apicoectomies.

  12. Effect of CO2, Nd:YAG, and Er:YAG lasers on dentin and pulp tissues in dogs (United States)

    Abt, Elliot; Wigdor, Harvey A.; Walsh, Joseph T., Jr.; Brown, Joseph D.


    Although there has been interest in lasers in dentistry since lasers were first developed in the early 1960's, this interest was limited until recently. Over the past five years there has been a flurry of interest to find the most effective wavelength and parameters of treatment. With this interest has come clinical and experimental reports. This project is a pilot study to investigate laser effects on dogs teeth. Multiple teeth from 2 dogs (n equals 40) were treated using either a CO2, Nd:YAG, or an Er:YAG laser, or slow-speed rotary instrumentation. One dog died after treatment and was not used in this study. The second dog was sacrificed four days after treatment with the lasers and the teeth were decalcified and processed for light microscopy. The dentin and pulpal tissues were then evaluated for changes from their normal histologic patterns. The purpose of this study was to first determine if the dog would be a good model for in-vivo histologic testing of lasers and second to evaluate the histologic effects of different lasers on dog's teeth. Our findings suggest that each laser causes a different degree of effect to the treated teeth. The specifics of these effects are discussed herein.

  13. Rapid tuning CW laser technique for measurements of gas velocity, temperature, pressure, density, and mass flux using NO (United States)

    Chang, Albert Y.; Dirosa, Michael D.; Davidson, David F.; Hanson, Ronald K.


    An intracavity-doubled rapid-tuning CW ring dye laser was used to acquire fully resolved absorption profiles of NO line pairs in the A-X band at 225 nm at a rate of 4 kHz. These profiles were utilized for simultaneous measurements of flow parameters in the high-speed 1D flows generated in a shock tube. Velocity was determined from the Doppler shift, measured using a pair of profiles simultaneously acquired at different angles with respect to the flow direction. Temperature was determined from the intensity ratio of the adjacent lines. Pressure and density were found both from the collisional broadening and the fractional absorption. From this information the mass flux was determined. The results compare well to 1D shock calculations.

  14. Combination of CO2 and Q-switched Nd:YAG lasers is more effective than Q-switched Nd:YAG laser alone for eyebrow tattoo removal. (United States)

    Radmanesh, Mohammad; Rafiei, Zohreh


    The eyebrow tattoo removal using Q-switched lasers is usually prolonged. Other modalities may be required to enhance the efficacy and shorten the treatment course. To compare the efficacy of Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser alone versus combination of Q-switched Nd:YAG and Ultrapulse CO2 lasers for eyebrow tattoo removal after a single session. After local anesthesia, the right eyebrow of 20 patients was treated with Ultrapulse CO2 laser with the parameters of 4 J/cm(2) and 3.2 J/cm(2) for the first and the second passes. Both eyebrows were then treated with 1064-nm and 532-nm Q-switched Nd:YAG laser. The spot size and pulse duration were 3 mm and 5 nanoseconds for both wavelengths, and the fluence was 7 J/cm(2) for 1064 nm and 3 J/cm (2) for 532 nm. The side treated with combination of Q-switched Nd:YAG and CO2 lasers improved 75-100% in 6 of 20 patients versus only 1 of 20 in the side treated with Q-switched Nd:YAG alone. Similarly, the right side in 13 of 20 patients showed more than 50% improvement with combination therapy versus the left side (the monotherapy side), where only 6 of 20 cases showed more than 50% improvement. The Mann-Whitney test was 2.85 for the right side and 1.95 for the left side (P value = 0.007). Using Ultra pulse CO2 laser enhances the efficacy of Q-switched Nd:YAG laser in eyebrow tattoo removal.

  15. Recent Results in High Power CO2-Laser Cutting for Shipbuilding Industry

    DEFF Research Database (Denmark)

    Olsen, Flemming Ove; Juhl, Thomas Winther; Nielsen, Jakob Skov


    In 1997 a high power laser cutting and welding test facility was established at the Danish shipyard Odense Steel Shipyard (OSS). Research and development projects were initiated in order to establish the basis for applying the full power of the laser for laser-cutting, by developing mirror based ...... cutting systems. In this paper the results of these projects will be presented....

  16. Topotactic changes on η-Mo4O11 caused by biased atomic force microscope tip and cw-laser

    International Nuclear Information System (INIS)

    Borovšak, Miloš; Šutar, Petra; Goreshnik, Evgeny; Mihailovic, Dragan


    Highlights: • We report influencing electronic properties of η-Mo 4 O 11 . • With the biased AFM tip we induce the surface potential changes on η-Mo 4 O 11 . • We used cw-laser to induced similar effect on surface potential on η-Mo 4 O 11 . • We do not influence the surface and topography of the samples. • No change in topography of samples indicates the topotactic transformation. - Abstract: We present topotactic changes on Mo 4 O 11 crystals induced by a biased atomic force microscope tip and continuous laser. The transformation does not change the topography of the samples, while the surface potential shows remarkable changes on areas where the biased AFM tip was applied. No structural changes were observed by Raman spectroscopy, but AFM scans revealed changes to surface potential due to laser illumination. The observed phenomenon could be potentially useful for memristive memory devices considering the fact that properties of other molybdenum oxides vary from metallic to insulators.

  17. Chemical, morphological and thermal effects of 10.6-microm CO2 laser on the inhibition of enamel demineralization. (United States)

    Steiner-Oliveira, Carolina; Rodrigues, Lidiany K A; Soares, Luís E S; Martin, Airton A; Zezell, Denise M; Nobre-dos-Santos, Marinês


    Studies have shown that enamel can be modified by pulsed CO2 laser to form a more acid-resistant substrate. This study evaluated the effects of a 10.6-microm CO2 laser on enamel surface morphology and chemical composition as well as monitored intrapulpal temperature changes during irradiation. Human teeth were irradiated with fluences of 1.5-11.5 J/cm2, and pulpal thermal as well as chemical and morphological modifications on enamel were assessed. The teeth were submitted to a pH-cycling model, and the mineral loss was determined by means of cross-sectional microhardness. For all irradiated groups, intrapulpal temperature changes were below 3 degrees C. FT-Raman spectroscopy and scanning electron microscopy indicated that fluences as low as 6.0 J/cm2 were sufficient to induce chemical and morphological changes in enamel. Then, for fluences reaching or exceeding 10.0 J/cm2, laser-induced inhibitory effects on demineralization were observed. It was thus concluded that laser energy density in the range of 10.0 and 11.5 J/cm2 could be applied to dental enamel in order to produce chemical and morphological changes and reduce the acid reactivity of enamel without compromising the pulp vitality.

  18. The Effects of CO2 Laser with or without Nanohydroxyapatite Paste in the Occlusion of Dentinal Tubules

    Directory of Open Access Journals (Sweden)

    Mohammed Abbood Al-maliky


    Full Text Available The aim of this study was to evaluate a new treatment modality for the occlusion of dentinal tubules (DTs via the combination of 10.6 µm carbon dioxide (CO2 laser and nanoparticle hydroxyapatite paste (n-HAp. Forty-six sound human molars were used in the current experiment. Ten of the molars were used to assess the temperature elevation during lasing. Thirty were evaluated for dentinal permeability test, subdivided into 3 groups: the control group (C, laser only (L−, and laser plus n-HAp (L+. Six samples, two per group, were used for surface and cross section morphology, evaluated through scanning electron microscope (SEM. The temperature measurement results showed that the maximum temperature increase was 3.2°C. Morphologically groups (L− and (L+ presented narrower DTs, and almost a complete occlusion of the dentinal tubules for group (L+ was found. The Kruskal-Wallis nonparametric test for permeability test data showed statistical differences between the groups (P<0.05. For intergroup comparison all groups were statistically different from each other, with group (L+ showing significant less dye penetration than the control group. We concluded that CO2 laser in moderate power density combined with n-HAp seems to be a good treatment modality for reducing the permeability of dentin.

  19. Surface modification of the titanium implant using TEA CO 2 laser pulses in controllable gas atmospheres - Comparative study (United States)

    Ciganovic, J.; Stasic, J.; Gakovic, B.; Momcilovic, M.; Milovanovic, D.; Bokorov, M.; Trtica, M.


    Interaction of a TEA CO2 laser, operating at 10.6 μm wavelength and pulse duration of 100 ns (FWHM), with a titanium implant in various gas atmospheres was studied. The Ti implant surface modification was typically studied at the moderate laser beam energy density/fluence of 28 J/cm2 in the surrounding of air, N2, O2 or He. The energy absorbed from the TEA CO2 laser beam is partially converted to thermal energy, which generates a series of effects, such as melting, vaporization of the molten material, shock waves, etc. The following titanium implant surface changes and phenomena were observed, depending on the gas used: (i) creation of cone-like surface structures in the atmospheres of air, N2 and O2, and dominant micro-holes/pores in He ambient; (ii) hydrodynamic features, most prominent in air; (iii) formation of titanium nitride and titanium oxide layers, and (iv) occurrence of plasma in front of the implant. It can be concluded from this study that the reported laser fluence and gas ambiences can effectively be applied for enhancing the titanium implant roughness and creation of titanium oxides and nitrides on the strictly localized surface area. The appearance of plasma in front of the implants indicates relatively high temperatures created above the surface. This offers a sterilizing effect, facilitating contaminant-free conditions.

  20. Ann modeling of kerf transfer in Co2 laser cutting and optimization of cutting parameters using monte carlo method

    Directory of Open Access Journals (Sweden)

    Miloš Madić


    Full Text Available In this paper, an attempt has been made to develop a mathematical model in order to study the relationship between laser cutting parameters such as laser power, cutting speed, assist gas pressure and focus position, and kerf taper angle obtained in CO2 laser cutting of AISI 304 stainless steel. To this aim, a single hidden layer artificial neural network (ANN trained with gradient descent with momentum algorithm was used. To obtain an experimental database for the ANN training, laser cutting experiment was planned as per Taguchi’s L27 orthogonal array with three levels for each of the cutting parameters. Statistically assessed as adequate, ANN model was then used to investigate the effect of the laser cutting parameters on the kerf taper angle by generating 2D and 3D plots. It was observed that the kerf taper angle was highly sensitive to the selected laser cutting parameters, as well as their interactions. In addition to modeling, by applying the Monte Carlo method on the developed kerf taper angle ANN model, the near optimal laser cutting parameter settings, which minimize kerf taper angle, were determined.