Sample records for yag laser thomson

  1. Development of a YAG laser system for the edge Thomson scattering system in ITER.

    Hatae, T; Yatsuka, E; Hayashi, T; Yoshida, H; Ono, T; Kusama, Y


    A prototype YAG laser system for the edge Thomson scattering system in ITER has been newly developed. Performance of the laser amplifier was improved by using flow tubes made of samarium-doped glass; the small signal gain reached 20 at its maximum. As a result, an output energy of 7.66 J at 100 Hz was successfully achieved, and the performance exceeded the target performance (5 J, 100 Hz).

  2. Thomson scattering from laser plasmas

    Moody, J D; Alley, W E; De Groot, J S; Estabrook, K G; Glenzer, S H; Hammer, J H; Jadaud, J P; MacGowan, B J; Rozmus, W; Suter, L J; Williams, E A


    Thomson scattering has recently been introduced as a fundamental diagnostic of plasma conditions and basic physical processes in dense, inertial confinement fusion plasmas. Experiments at the Nova laser facility [E. M. Campbell et al., Laser Part. Beams 9, 209 (1991)] have demonstrated accurate temporally and spatially resolved characterization of densities, electron temperatures, and average ionization levels by simultaneously observing Thomson scattered light from ion acoustic and electron plasma (Langmuir) fluctuations. In addition, observations of fast and slow ion acous- tic waves in two-ion species plasmas have also allowed an independent measurement of the ion temperature. These results have motivated the application of Thomson scattering in closed-geometry inertial confinement fusion hohlraums to benchmark integrated radiation-hydrodynamic modeling of fusion plasmas. For this purpose a high energy 4{omega} probe laser was implemented recently allowing ultraviolet Thomson scattering at various locations in high-density gas-filled hohlraum plasmas. In partic- ular, the observation of steep electron temperature gradients indicates that electron thermal transport is inhibited in these gas-filled hohlraums. Hydrodynamic calcula- tions which include an exact treatment of large-scale magnetic fields are in agreement with these findings. Moreover, the Thomson scattering data clearly indicate axial stagnation in these hohlraums by showing a fast rise of the ion temperature. Its timing is in good agreement with calculations indicating that the stagnating plasma will not deteriorate the implosion of the fusion capsules in ignition experiments.

  3. Thomson scattering from laser induced plasma in air

    Dzierzega, K; Mendys, A [Institute of Physics, Jagiellonian University, ul. Reymonta 4, 30-059 Krakow (Poland); Pellerin, S; Thouin, E [GREMI - site de Bourges, Universite d' Orleans, rue Gaston Berger BP 4043, 18028 Bourges (France); Travaille, G; Bousquet, B; Canioni, L [Centre de Physique Moleculaire Optique et Hertzienne, Universite Bordeaux I, 351 Cours de la Liberation, 33405 Talence CEDEX (France); Pokrzywka, B, E-mail: [Mt. Suhora Observatory, Pedagogical University of Cracow, ul. Podchorazych 2, 30-084 Krakow (Poland)


    The laser induced plasma in air produced by 6 ns, 532 nm Nd:YAG pulses with 25 mJ energy was studied using the Thomson scattering method and plasma imaging techniques. Plasma images and Thomson scattered spectra were registered at delay times ranging from 150 ns to 1 {mu}s after the breakdown pulses. The electron density and temperature, as determined in the core of the plasma plume, were found to decrease from 7.4 x 10{sup 17} cm{sup -3} to about 1.03 x 10{sup 17} cm{sup -3} and from 100 900 K to 22 700 K. The highly elevated electron temperatures are the result of plasma heating by the second, probe pulse in the Thomson scattering experiments.

  4. Laser Thomson scattering in a pulsed atmospheric arc discharge

    Sommers, Bradley; Adams, Steven


    Laser scattering measurements, including Rayleigh, Raman, and Thomson scattering have been performed on an atmospheric pulsed arc discharge. Such laser scattering techniques offer a non-invasive diagnostic to measure gas temperature, electron temperature, and electron density in atmospheric plasma sources, particularly those with feature sizes approaching 1 mm. The pulsed discharge is ignited in a pin to pin electrode geometry using a 6 kV pulse with 10 ns duration. The electrodes are housed in a glass vacuum chamber filled with argon gas. The laser signal is produced by a Nd:Yag laser supply, repetitively pulsed at 10 Hz and frequency quadrupled to operate at 266 nm. The scattered laser signal is imaged onto a triple grating spectrometer, which is used to suppress the Rayleigh scatter signal in order to measure the low amplitude Thomson and Raman signals. Preliminary results include measurements of electron temperature and electron density in the plasma column taken during the evolution of the discharge. The laser system is also used to measure the Rayleigh scattering signal, which provides space and time resolved measurements of gas temperature in the arc discharge.

  5. Investigations of laser-induced plasma in argon by Thomson scattering

    Mendys, A., E-mail: [Instytut Fizyki im. M. Smoluchowskiego, Uniwersytet Jagiellonski, ulica Reymonta 4, 30-059 Krakow (Poland); Dzierzega, K.; Grabiec, M. [Instytut Fizyki im. M. Smoluchowskiego, Uniwersytet Jagiellonski, ulica Reymonta 4, 30-059 Krakow (Poland); Pellerin, S. [GREMI - site de Bourges, Universite d' Orleans, CNRS, rue Gaston Berger BP 4043, 18028 Bourges (France); Pokrzywka, B. [Obserwatorium Astronomiczne na Suhorze, Uniwersytet Pedagogiczny, ulica Podchorazych 2, 30-084 Krakow (Poland); Travaille, G.; Bousquet, B. [Centre de Physique Moleculaire Optique et Hertzienne, Universite Bordeaux 1, 351 Cours de la Liberation, 33405 Talence CEDEX (France)


    The Thomson scattering method was applied to quantify the electron number density and temperature of a laser spark formed in argon. The laser spark was generated by focusing a 15 mJ beam from the second harmonic ({lambda}{sub L} = 532 nm) of a nanosecond Nd:YAG laser with an 80 mm focal length lens. Images of the spark emission were obtained for times between 1 ns and 20 {mu}s after the laser pulse in order to characterize its spatial evolution. The electron density and temperature for the core of the plasma plume at different instants of its evolution were determined from the Thomson scattered spectra of another nanosecond Nd:YAG laser (532 nm, 10 to 60 mJ/pulse). In the time interval between 400 ns and 10 {mu}s between the laser induced plasma and Thomson scattering probe pulses, we found n{sub e} and T{sub e} to decrease from 4.3 Multiplication-Sign 10{sup 23} m{sup -3} to 2.4 Multiplication-Sign 10{sup 22} m{sup -3} and from 50 700 K to 11 100 K, respectively. Special care was paid to the plasma disturbance by the probe laser pulse in Thomson scattering experiments due to absorption of laser photons by electrons through the inverse bremsstrahlung process.

  6. Erbium: YAG laser lithotripsy mechanism.

    Chan, Kin Foong; Lee, Ho; Teichman, Joel M H; Kamerer, Angela; McGuff, H Stan; Vargas, Gracie; Welch, Ashley J


    We tested the hypothesis that the mechanism of long pulse erbium:YAG laser lithotripsy is photothermal. Human urinary calculi were placed in deionized water and irradiated with erbium:YAG laser energy delivered through a sapphire optical fiber. Erbium:YAG bubble dynamics were visualized with Schlieren flash photography and correlated to acoustic emissions measured by a polyvinylidene fluoride needle hydrophone. The sapphire fiber was placed either parallel or perpendicular to the calculus surface to assess the contribution of acoustic transients to fragmentation. Stones were irradiated using desiccated stone irradiated in air, hydrated stone irradiated in air and hydrated stone irradiated in water. Ablation crater sizes were compared. Uric acid stones were irradiated in water and the water was assayed for cyanide. During the early phase of vapor bubble expansion, acoustic transients had minimal effects on calculus fragmentation. Fragmentation occurred due to direct absorption of laser energy transmitted to the calculus through the vapor channel between the sapphire fiber tip and calculus. The forward axial expansion of the bubble occurred more rapidly than the radial expansion. A parallel oriented fiber on the calculus surface produced no fragmentation but generated larger amplitude acoustic transients compared to perpendicular orientation. In perpendicular orientation the erbium:YAG laser did not generate any collapse acoustic waves but fragmentation occurred. Crater width was greatest for desiccated stones irradiated in air (p <0.03). Cyanide production increased as erbium:YAG irradiation of uric acid calculi increased, (r2 = 0.98). The erbium:YAG laser fragments stones through a photothermal mechanism.

  7. Laser-diode pumped Nd:YAG lasers; Laser diode reiki Nd:YAG lasear

    Yuasa, H.; Akiyama, Y.; Nakayama, M. [Toshiba Corp., Tokyo (Japan)


    Laser-diode pumped Nd:YAG lasers are expected to be applied to laser processing fields such as welding, cutting, drilling, and marking due to their potential for high efficiency and compactness. We are designing and developing laser-diode pumped Nd:YAG lasers using numerical analysis simulation techniques such as ray tracing and thermal analysis. We have succeeded in achieving a laser power of more than 3 kW with 20% efficiency, which is the best ever obtained. In addition, we have developed a laser-diode pumped green laser by second harmonic generation, for precision machining on silicon wafers. (author)

  8. Design and Operation of a Frequency Doubled Nd:YAG Thomson Scattering System with Transmission Grating ICCD Spectrometer

    Schoenbeck, N. L.; Dowd, A. S.; Fonck, R. J.; Schlossberg, D. J.; Winz, G. R.


    A novel Thomson scattering system has been deployed on the Pegasus Toroidal Experiment. It provides a relatively low-cost, simplified design. Scattering is achieved using a 7 ns, 2 J frequency doubled Nd:YAG laser operating at 532 nm. The laser focuses to ˜3 mm diameter within the plasma via a 7 m beam-line. The beam-line contains cameras as beam finders and remotely adjustable mirrors for shot-to-shot alignment. A custom multi-element lens collects scattered photons from 15 cm 40%) image intensified CCD (ICCD) camera. Three spectrometers provide a total of 24 channels. Two interchangeable gratings exist to cover low (Te = 10--100 eV) and high (Te = 0.10--1 keV) electron temperature regimes on Pegasus. The spectrometer is optimized for ne from mid-10^18 to mid-10^19 m-3. The signal-to-noise expected is ˜0.5 of an equivalent system using Nd:YAG at 1064 nm and avalanche photodiode detectors.

  9. Thomson scattering of polarized photons in an intense laser beam

    Byung Yunn


    We present a theoretical analysis of the Thomson scattering of linearly and circularly polarized photons from a pulsed laser by electrons. The analytical expression for the photon distribution functions presented in this paper should be useful to designers of Thomson scattering experiments.

  10. Pulsed Laser Nonlinear Thomson Scattering for General Scattering Geometries

    Geoffrey Krafft; A. Doyuran; James Rosenzweig


    In a recent paper it has been shown that single electron Thomson backscatter calculations can be performed including the effects of pulsed high intensity lasers. In this paper we present a more detailed treatment of the problem and present results for more general scattering geometries. In particular, we present new results for 90 degree Thomson scattering. Such geometries have been increasingly studied as X-ray sources of short-pulse radiation. Also, we present a clearer physical basis for these different cases.

  11. Laser properties of yag: Nd, Cr, Ce

    Kvapil, J.; Kvapil, Jos; Perner, B.; Kubelka, J.; Mánek, B.; Kubeček, V.


    Transient absorption of a long lifetime (≧ 20 s) of YAG: Nd is typical of pure material. It is the main reason of thermal deformation of the laser rods accompanied with power decreases at higher CW input. It may be prevented by an admixture of Fe, Ti or Cr. Using a small admixture (≦ 10-3 wt.%) of Ti or Cr the energy transfer among Nd ions and the gain coefficient may be increased. Cr in a higher concentration absorbs the pumping light and serves as earlier described coactivator (sensitizer) only. Fe impurity fully prevents any increase of the gain of YAG: Nd containing Ti or Cr and causes slow but irreversible degradation of the active parameters. Ce favourably modifies properties of YAG: Nd, Cr. YAG: Nd, Cr, Ce free of iron impurity is advisable active material for powerfull CW lasers.

  12. Ceramic planar waveguide laser of non-aqueous tape casting fabricated YAG/Yb:YAG/YAG.

    Wang, Chao; Li, Wenxue; Yang, Chao; Bai, Dongbi; Li, Jiang; Ge, Lin; Pan, Yubai; Zeng, Heping


    Ceramic YAG/Yb:YAG/YAG planar waveguide lasers were realized on continuous-wave and mode-locked operations. The straight waveguide, fabricated by non-aqueous tape casting and solid state reactive sintering, enabled highly efficient diode-pumped waveguide continuous-wave laser with the slope efficiency of 66% and average output power of more than 3 W. The influence of the waveguide structure on the wavelength tunability was also experimentally investiccgated with a dispersive prism. Passively mode-locked operation of the ceramic waveguide laser was achieved by using a semiconductor saturable absorber mirror (SESAM), output 2.95 ps pulses with maximum power of 385 mW at the central wavelength of 1030 nm.

  13. Development of laser beam injection system for the Edge Thomson Scattering (ETS) in ITER

    Yatsuka, E.; Hatae, T.; Suitoh, S.; Ohara, M.; Hagita, K.; Inoue, K.; Bassan, M.; Walsh, M.; Itami, K.


    This paper focuses on the design and development of the laser injection system for the ITER Edge Thomson Scattering system (ETS). The ITER ETS achieves a temporal resolution of 100 Hz by firing two 50 Hz laser beams alternatively. The use of dual lasers enables us to perform the Thomson scattering measurements at a temporal resolution of 50 Hz in case that one of the laser systems stops functioning. A new type of beam combiner was developed to obtain a single beam that is collinear and fixed linearly polarized from two laser beams using a motor-driven rotating half-wave plate. The rotating half-wave plate method does not induce misalignment even if the rotating mechanism malfunctions. The combined beam is relayed from the diagnostic hall to the plasma using mirror optics and is absorbed at the beam dump integrated on the inner blanket. The beam alignment system was designed to direct the laser beam onto the center of the beam dump head. The beam position at the beam dump is monitored by four alignment laser beams which propagate parallel to the diagnostic Nd:YAG laser beam and imaging systems installed outside the diagnostic port.

  14. Plasma Jet Interaction with Thomson Scattering Probe Laser

    Byvank, Tom; Banasek, Jacob; Potter, William; Kusse, Bruce


    Thomson scattering systems can diagnose plasma temperatures and velocities. When probing a plasma jet with the Thomson scattering laser, we observe a laser-plasma interaction that inputs energy into the plasma jet. The absorbed energy causes a bubble of low density ( 5*1017 cm-2) in the jet (unperturbed 1018 cm-2). A pulsed power machine (1 MA peak current, 100 ns rise time) with a radial foil (15 μm thick Al) configuration generates the plasma jet. We compare the effects of using 10 J and 1 J laser energies, for which the 10 J laser is a larger perturbation. We discuss how the interaction affects the Thomson scattering temperature and velocity measurements. Work supported by National Nuclear Security Administration (NNSA) Stewardship Sciences Academic Programs under Department of Energy (DOE) Cooperative Agreement DE-NA0001836 and National Science Foundation (NSF) Grant PHY-1102471.

  15. YAG laser welding with surface activating flux

    樊丁; 张瑞华; 田中学; 中田一博; 牛尾诚夫


    YAG laser welding with surface activating flux has been investigated, and the influencing factors and mechanism are discussed. The results show that both surface activating flux and surface active element S have fantastic effects on the YAG laser weld shape, that is to obviously increase the weld penetration and D/W ratio in various welding conditions. The mechanism is thought to be the change of weld pool surface tension temperature coefficient, thus, the change of fluid flow pattern in weld pool due to the flux.

  16. Collective Thomson Scattering from Laser-Produced Plasmas

    白波; 郑坚; 俞昌旋; 刘万东; 蒋小华; 袁晓东; 郑志坚; 徐冰; 向勇; 赵春茁


    Time-resolved Thomson scattering was successfully performed to diagnose the parameters (ZTe, Ue and Ui) of laser-produced gold plasma. The results show that the collisionless dynamic form factor is accurate enough to be used for reducing the plasma parameters from the experimental data.

  17. Laser properties of YAG:Nd, Ti

    Kvapil, J.; Kvapil, J.; Kubelka, K. J.; Perner, B.


    YAG:Nd containing about 0.001 wt percent Ti showed slightly increased losses at 1.064 micron but a substantially increased gain coefficient if compared with a material containing no Ti. The increased losses may be attributed to the increased absorption near 1.064 nm and the increased gain to the better energy coupling among Nd(3+) ions occupying nonequivalent sites due to the presence of Ti(3+) ions. YAG:Nd, Ti may be used as a high performance pulsed laser.

  18. Diode pumped Nd:YAG laser development

    Reno, C. W.; Herzog, D. G.


    A low power Nd:YAG laser was constructed which employs GaAs injection lasers as a pump source. Power outputs of 125 mW TEM CW with the rod at 250 K and the pump at 180 K were achieved for 45 W input power to the pump source. Operation of the laser, with array and laser at a common heat sink temperature of 250 K, was inhibited by difficulties in constructing long-life GaAs LOC laser arrays. Tests verified pumping with output power of 20 to 30 mW with rod and pump at 250 K. Although life tests with single LOC GaAs diodes were somewhat encouraging (with single diodes operating as long as 9000 hours without degradation), failures of single diodes in arrays continue to occur, and 50 percent power is lost in a few hundred hours at 1 percent duty factor. Because of the large recent advances in the state of the art of CW room temperature AlGaAs diodes, their demonstrated lifetimes of greater than 5,000 hours, and their inherent advantages for this task, it is recommended that these sources be used for further CW YAG injection laser pumping work.

  19. End-Pumped Tm:YAG Ceramic Slab Lasers

    CHENG Xiao-Jin; XU Jian-Qiu; ZHANG Wen-Xin; JIANG Sen-Xue; PAN Yu-Bai


    Lasers from a Tm:YAG ceramic aare reported for the first time to our best knowledge. The Tm:YAG ceramic slab is end-pumped by a laser diode with central wavelength 792nm. At room temperature, the maximum continuous-wave output power is 4.5 W, and the sloping efficiency is obtained to be 20.5%. The laser spectrum of the Tm: YAG ceramic is centered at 2015 nm.

  20. Peak intensity measurement of relativistic lasers via nonlinear Thomson scattering

    Har-Shemesh, Omri


    The measurement of peak laser intensities exceeding $10^{20}\\;\\text{W/cm$^2$}$ is in general a very challenging task. We suggest a simple method to accurately measure such high intensities up to about $10^{23}\\,\\text{W/cm$^2$}$, by colliding a beam of ultrarelativistic electrons with the laser pulse. The method exploits the specific features of the angular distribution of the radiation emitted by ultrarelativistic electrons via nonlinear Thomson scattering. Initial electron energies well within the reach of laser wake-field accelerators are required, allowing in principle for an all-optical setup. Accuracies of the order of 10% are envisaged.

  1. YAG Laser Treatment of Tinea Pedis

    Ueda, Masahiro; KAGAWA, Kiichiro


    A clinical experiment on the treatment of tinea pedis infections (common as an athlete’s foot) was conducted using a pulsed Nd-YAG laser with an output energy of 0.5 joule/pulse and duration of 1 millisecond. The experiment was supported by 13 volunteers for skin samples used in this experiment. The treatment was performed with the following irradiation condition; an energy density of 400 joule/cm2 at a skin sample surface, a spot diameter of the laser beam on the surface of 0.4 mm and a re...

  2. Fractional ablative erbium YAG laser

    Taudorf, Elisabeth H; Haak, Christina S; Erlendsson, Andrés M


    BACKGROUND AND OBJECTIVES: Treatment of a variety of skin disorders with ablative fractional lasers (AFXL) is driving the development of portable AFXLs. This study measures micropore dimensions produced by a small 2,940 nm AFXL using a variety of stacked pulses, and determines a model correlating...... laser parameters with tissue effects. MATERIALS AND METHODS: Ex vivo pig skin was exposed to a miniaturized 2,940 nm AFXL, spot size 225 µm, density 5%, power levels 1.15-2.22 W, pulse durations 50-225 microseconds, pulse repetition rates 100-500 Hz, and 2, 20, or 50 stacked pulses, resulting in pulse...... 190 to 347 µm. CONCLUSIONS: Pulse stacking with a small, low power 2,940 nm AFXL created reproducible shallow to deep micropores, and influenced micropore configuration. Mathematical modeling established relations between laser settings and micropore dimensions, which assists in choosing laser...

  3. Investigation of the local thermodynamic equilibrium of laser-induced aluminum plasma by Thomson scattering technique

    Mendys, A., E-mail: [Instytut Fizyki im. M. Smoluchowskiego, Uniwersytet Jagielloński, ul. Reymonta 4, 30-059 Kraków (Poland); Kański, M. [Instytut Fizyki im. M. Smoluchowskiego, Uniwersytet Jagielloński, ul. Reymonta 4, 30-059 Kraków (Poland); Farah-Sougueh, A. [Instytut Fizyki im. M. Smoluchowskiego, Uniwersytet Jagielloński, ul. Reymonta 4, 30-059 Kraków (Poland); GREMI — site de Bourges, Université d' Orléans, CNRS, rue Gaston Berger BP 4043, 18028 Bourges (France); Pellerin, S. [GREMI — site de Bourges, Université d' Orléans, CNRS, rue Gaston Berger BP 4043, 18028 Bourges (France); Pokrzywka, B. [Obserwatorium Astronomiczne na Suhorze, Uniwersytet Pedagogiczny, ul. Podchorażych 2, 30-084 Kraków (Poland); Dzierżęga, K. [Instytut Fizyki im. M. Smoluchowskiego, Uniwersytet Jagielloński, ul. Reymonta 4, 30-059 Kraków (Poland)


    A laser Thomson scattering method was applied to investigate the local Saha–Boltzmann equilibrium in aluminum laser-induced plasma. Plasma was created in ambient air using 4.5 ns pulses from a Nd:YAG laser at 532 nm, focused on an Al target. Spatially resolved measurements, performed for the time interval between 600 ns and 3 μs, show electron density and temperature to decrease from 3.4 × 10{sup 23} m{sup −3} to 0.5 × 10{sup 23} m{sup −3} and from 61,000 K to 13,000 K in the plasma core. The existence of local thermodynamic equilibria in the plasma was verified by comparing the rates of the collisional to radiative processes (the McWhirter criterion), as well as relaxation times and diffusion lengths of different plasma species, with the appropriate rate of electron density evolution and its gradients at given, experimentally determined, electron temperatures. We found these criteria to be much easier to satisfy for metallic plasma species than for nitrogen. The criteria are also easier to satisfy in the plasma core of higher electron density. - Highlights: • Laser Thomson scattering method was applied to investigate aluminum laser-induced plasma. • Spatio-temporal evolution of electron temperature and density was determined. • Three criteria for existence of local thermodynamic equilibrium were verified. • Criteria are much easier to satisfy for metallic plasma species than for nitrogen. • Criteria are easier to satisfy at earlier times and in the plasma core.

  4. Tapered diode laser pumped 946 nm Nd:YAG laser

    Cheng, Haynes Pak Hay; Jensen, Ole Bjarlin; Petersen, Paul Michael


    We successfully implemented a 946 nm Nd:YAG laser based on a 808 nm tapered diode pump laser. The tapered diode is developed at the Ferdinand-Braun-Institute fur Hochstfrequenztechnik in Germany. Figure 2 shows the experimental setup and results of each pump source coupled into a 1.5 mm crystal...... laser, we show that tapered diode laser pumping potentially increase the power of 946 nm lasers by a factor of two and reduce the threshold by a factor of three....

  5. Pulsed Nd-YAG laser in endodontics

    Ragot-Roy, Brigitte; Severin, Claude; Maquin, Michel


    The purpose of this study was to establish an operative method in endodontics. The effect of a pulsed Nd:YAG laser on root canal dentin has been examined with a scanning electron microscope. Our first experimentation was to observe the impacts carried out perpendicularly to root canal surface with a 200 micrometers fiber optic in the presence of dye. Secondarily, the optical fiber was used as an endodontic instrument with black dye. The irradiation was performed after root canal preparation (15/100 file or 40/100 file) or directly into the canal. Adverse effects are observed. The results show that laser irradiation on root canal dentin surfaces induces a nonhomogeneous modified dentin layer, melted and resolidified dentin closed partially dentinal tubules. The removal of debris is not efficient enough. The laser treatment seems to be indicated only for endodontic and periapical spaces sterilization after conventional root canal preparation.

  6. Demining with Nd:YAG laser

    Rothacher, Thomas; Lüthy, Willy; Weber, Heinz P.


    Laser neutralization of antipersonnel (AP) mines offers the enormous advantage to work from a safe distance. In this article the interaction of Nd:YAG laser radiation and four different types of blast AP mines is investigated. For this purpose, a very compact laser system for mine neutralization is developed. The incident power on the mine surfaces is varied from 20 to 70 W. Neutralization of all mines is achieved from a safe distance up to 50 m. The mines burn and finally detonate after an irradiation time of a few minutes. Detonation of the irradiated burning mines is considerably weaker compared to fully functional mines. Therefore, expected damage in the surrounding area is significantly reduced.

  7. Cryogenic Yb: YAG Thin-Disk Laser


    Spitzberg, "Cryogenic Yb3+-Doped Solid-State Lasers," IEEE Journ. of Sel. Topics in Quant. Elect., 13(3), 448-459 (2007). [3] S. Tokita, J. Kawanaka, M...Europe ( IEEE ,2005) ,CTu3 (2005). [4] D. C. Brown, J. M. Singley, E. Yager, J. W. Kuper, B. J. Lotito, L. L. Bennett, "Innovative high-power CW...Y. Sun, and R. W. Equall, "Yb:YAG Absorption at Ambient and Cryogenic Temperatures," IEEE Journ. Sel. Topics Quant. Elect. 11(3), 604-612 (2005

  8. Deicing with Nd:YAG and CO2 lasers

    Qi, Lijun; Zhu, Xiao; Zhu, Changhong; Guo, Fei; Zhu, Guangzhi; Gu, Shanqiang


    A model of deicing with Nd:YAG and CO2 lasers for simulation using ANSYS software is presented. Experiments with a 300-W, 1-ms, 60-Hz Nd:YAG laser and a 500- to 2000-W cw CO2 laser are reported. The Nd:YAG laser is considered as a volume thermal source, and the CO2 laser as a plane thermal source. The model and the simulation results can describe both Nd:YAG and CO2 laser deicing well. The results of the simulation and experiments suggest that the melting rates for the two lasers are almost equal at the same laser power density. So are the melting efficiencies. The hard and transparent ice irradiated by the Nd:YAG laser becomes opaque and loose, because the thermal stress is distributed in the body of the ice, while the ice irradiated by the CO2 laser is still transparent and hard, because thermal stress hardly occurs. So the laser with characteristics of high output power and large ice absorbing length can be selected for the power line laser deicing system, and Nd:YAG laser is more appropriate for power-line deicing than CO2 laser.

  9. Cryogenic Yb:YAG thin-disk laser

    Vretenar, N.; Carson, T.; Lucas, T.; Newell, T.; Latham, W. P.; Peterson, P.; Bostanci, H.; Lindauer, J. J.; Saarloos, B. A.; Rini, D. P.


    At cryogenic temperatures, Yb:YAG behaves as a 4-level laser. Its absorption and emission cross-sections increase, and its thermal conductivity improves. Yb:YAG thin disk laser performance at room and cryogenic (80°K) temperatures will be presented. The Yb:YAG gain media is cooled using either a pressurized R134A refrigerant system or by a two-phase liquid nitrogen spray boiler. Interchangeable mounting caps allow the same Yb:YAG media to be switched between the two systems. This allows direct comparison of lasing, amplified spontaneous emission, and temperature performance between 20°C and -200°C.

  10. 用于汤姆孙散射诊断的高重频高光束质量焦耳级Nd:YAG纳秒激光器∗%High rep etition rate and high b eam quality joule level Nd:YAG nanosecond laser for Thomson scattering diagnosis

    邱基斯; 唐熊忻; 樊仲维; 陈艳中; 葛文琦; 王昊成; 刘昊


    A joule-level Nd:YAG nanosecond laser of high repetition frequency and high beam quality is developed for Thom-son scattering diagnosis. The laser is designed as a master oscillator power-amplifier system mainly including single longitudinal mode seed, pre-amplifier unit and energy extraction unit. The single-longitudinal-mode Q-switched laser of a high stability is taken as the seed laser of output pulse at µJ level. The pre-amplifier unit amplifies the µJ-level pulse laser beam into hundreds of mJ level. In order to obtain the high-quality laser beam output, phase conjugation is adopted to compensate for the laser beam distortion. The ultra-filtered FC-770 is taken as an SBS gain medium of 0.0011 cm−1 absorption coefficient, 197.9 GW/cm2 optical breakdown threshold and 3.5 cm/GW gain coefficient. The double-pass amplification of SBS phase conjugation could realize a real-time repair towards the non-uniformity, deformation and wavefront aberration caused by thermal distortion of the optical components and the laser amplifier to achieve the uniform amplified beam output of high quality close to the diffraction limit. In the energy extraction unit, the amplifier of large-diameter slab is used for energy amplification. The size of the slab is 7 mm × 35 mm × 138.2 mm of 56◦ cutting angle and 0.6% Nd3+ doping concentration. The slab is plated by a layer of SiO2 against light leak. Horizontal pumping mode is adopted. And the slow axis of the laser diode is almost the same as the length of the slat and the direction of laser transmission. The single-plane array is composed of 8 groups of vertical stacks and each group consists of 12 laser diode bars of power 200 W. At 200 Hz repetition frequency, 250 µs pump pulse width and 140 A pump current, the up to 2.3 J stored energy can be achieved The energy extraction unit achieves high gain amplification and finally outputs high-quality laser beam. Under the condition of 200 Hz high repetition frequency and 8.23 µ

  11. Improvement of thermal management in the composite Yb:YAG/YAG thin-disk laser

    Kuznetsov, I. I.; Mukhin, I. B.; Palashov, O. V.


    To improve the thermal management in the composite Yb:YAG/YAG thin-disk laser a new design of laser head is developed. Thermal-induced phase distortions, small signal gain and lasing in the upgraded laser head are investigated and compared with previously published results. A substantial decrease of the thermal lens optical power and phase aberrations and increase of the laser slope efficiency are observed. A continuous-wave laser with 440 W average power and 44% slope efficiency is constructed.

  12. Thomson scattering in high-intensity chirped laser pulses

    Holkundkar, Amol R., E-mail: [Department of Physics, Birla Institute of Technology and Science, Pilani, Rajasthan 333031 (India); Harvey, Chris, E-mail:; Marklund, Mattias, E-mail: [Department of Applied Physics, Chalmers University of Technology, SE-41296 Gothenburg (Sweden)


    We consider the Thomson scattering of an electron in an ultra-intense laser pulse. It is well known that at high laser intensities, the frequency and brilliance of the emitted radiation will be greatly reduced due to the electron losing energy before it reaches the peak field. In this work, we investigate the use of a small frequency chirp in the laser pulse in order to mitigate this effect of radiation reaction. It is found that the introduction of a negative chirp means the electron enters a high frequency region of the field while it still has a large proportion of its original energy. This results in a significant enhancement of the frequency and intensity of the emitted radiation as compared to the case without chirping.

  13. Development of density measurement method of negative ion in plasmas using laser Thomson scattering

    Yamagata, Yukihiko; Saiho, Hiroatsu; Uchino, Kiichiro; Muraoka, Katsunori


    Measurements of negative ion density in plasmas have been an important subject for many years. We have proposed a new method to measure the negative ion density in plasmas using laser Thomson scattering (LTS), and successfully measured O^- ion density in an radio frequency inductively coupled plasma [1]. In order to ensure the reliability of this technique and to estimate the accuracy, we have measured O^- ion density in the same experimental conditions using the second (SHG) and third harmonics (THG) of a Nd:YAG laser as different laser sources. The LTS spectra measured at pure argon plasma (500 W, 20 mTorr) fitted in a straight line well in both SHG and THG cases. As for the plasma at 500 W in 20 mTorr with Ar/O_2=95%/5%, a clear bump in LTS spectra, which is caused by photo-detached electrons, was observed below 0.9 eV for the SHG case and 2 eV for the case, as predicted by a difference between the electron affinity of O^- ion and the laser photon energy. The electron temperatures, the electron densities and the O^- ion densities, which were obtained from the spectral shape and intensity of both LTS spectra, were in agreement each other within an experimental error. [1] M. Noguchi, K. Ariga, T. Hirao, P. Suanpoot, Y. Yamagata, K. Uchino, K. Muraoka, Plasma Sources Sci. Technol., 11 (2002) 57.

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

    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

  16. CO(2), Er: YAG and Nd:YAG lasers in endodontic surgery.

    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.

  17. Microchip laser based on Yb:YAG/V:YAG monolith crystal

    Nejezchleb, Karel; Šulc, Jan; Jelínková, Helena; Škoda, Václav


    V:YAG crystal was investigated as a passive Q-switch of longitudinally diode-pumped microchip laser, emitting radiation at wavelength 1030.5 nm. This laser was based on diffusion bonded monolith crystal (diameter 3 mm) which combines in one piece an active laser part (Yb:YAG crystal, 10 at.% Yb/Y, 3 mm long) and saturable absorber (V:YAG crystal, 2 mm long, initial transmission 86 % @ 1031 nm). The microchip resonator consisted of dielectric mirrors directly deposited on the monolith surfaces (pump mirror HT @ 968 nm and HR @ 1031 nm on Yb:YAG part, output coupler with reflection 55 % @ 1031 nm on the V:YAG part). For longitudinal CW pumping of Yb:YAG part, a fibre coupled (core diameter 100 μm, NA = 0.22, emission @ 968 nm) laser diode was used. The laser threshold was 3.8W. The laser slope efficiency for output mean in respect to incident pumping was 16 %. The linearly polarized generated transversal intensity beam profile was close to the fundamental Gaussian mode. The generated pulse length, stable and mostly independent on pumping power, was equal to 1.3 ns (FWHM). The single pulse energy was increasing with the pumping power and for the maximum pumping 9.7W it was 78 μJ which corresponds to the pulse peak-power 56 kW. The maximum Yb:YAG/V:YAG microchip laser mean output power of 1W was reached without observable thermal roll-over. The corresponding Q-switched pulses repetition rate was 13.1 kHz.

  18. HT-7 Multipoint Nd Laser Thomson Scattering Apparatus


    A compact, low cost, multipoint Thomson scattering diagnostic system for HT-7 superconducting tokamak has been in operation since 1999. Its capability of measuring electron temperatures is in the range of 200 eV to 2 keV at a density of a few times 1012 cm-3, with a spatial resolution of 2.4 cm for 5 spatial points and a temporal resolution of 1 ms~1 s for 8 time points. The main components of the diagnostic system include a 20~25 J Nd:glass laser with 35 ns pulse width (8 pulses per burst), a KDP frequency-doubling unit, spherical mirrors of multipass input optical system, a wide-angle collection objective, a bandpass glass filter for reducing the stray light to zero, a f/2.5 polychromator, a fiberglass collimator, a photomultiplier's box with electronic preamplifier, high gain and high signal/noise ratio, CAMAC data acquisition and so on.The multipass optical system has been successful at increasing the quantity of scattered photons by passing the probing laser beam 10 times through the plasma under investigation. The HT7 Thomson scattering diagnostic has provided successfully the information on two-dimensional electron temperature in the plasma of HT-7 tokamak with LHCD and IBW.

  19. Stone Retropulsion with Ho: YAG and Tm: YAG Lasers: A Clinical Practice-Oriented Experimental Study.

    Kamal, Wissam; Kallidonis, Panagiotis; Koukiou, Georgia; Amanatides, Lefteris; Panagopoulos, Vasileios; Ntasiotis, Pantelis; Liatsikos, Evangelos


    To compare the retropulsion of stones with the use of holmium: yttrium aluminum garnet (Ho: YAG) laser and thulium: yttrium aluminum garnet (Tm: YAG) laser in settings that could be used in clinical practice. The experimental configuration included a glass tube set in a water bath filled with physiologic saline. Plaster of Paris stones were inserted in the tube. Tm: YAG and Ho: YAG laser systems were used along with a high-speed slow-motion camera. The lasers were activated with different settings. The displacement of the stone was measured according to a custom-made algorithm. Ho: YAG: the retropulsion of stones was the lowest with the energy setting of 0.5 J and the frequency of 20 Hz with long pulse duration. The highest retropulsion was observed in the case of 3 J, 5 Hz, and short pulse. Tm: YAG: the retropulsion of stones was the lowest with the energy setting of 1 J and the frequency of 10 Hz with either long or short pulse duration. Practically, there was no retropulsion at all. The highest retropulsion was observed in the case of 8 J, 5 Hz, and short pulse. Ho: YAG laser has a linear increase in stone retropulsion with increased pulse energy. On the other hand, the retropulsion rate was kept to the minimum with Tm: YAG as much as the energy level of 8 J. The activation of lasers with short pulse resulted in further displacement of the stone. Lower frequency with the same power setting seemed to result in further stone retropulsion. Higher power with the same frequency setting resulted in further displacement of the stone.

  20. Er:YAG laser radiation etching of enamel

    Dostalova, Tatjana; Jelinkova, Helena; Krejsa, Otakar; Hamal, Karel; Kubelka, Jiri; Prochazka, Stanislav


    This study compares the effects of acid treatment and Er:YAG laser radiation on the enamel. The permanent human molars were used. Oval cavities in the buccal surface were prepared and the edges of cavities were irradiated by Er:YAG radiation. The energy of laser was 105 mJ and repetition rate 1 Hz. The radiation was focused by CaF2 lens and the sample was placed in the focus. Ten samples were etched by 35 percent phosphoric acid during 60 s. Than cavities were filled with composite resin following manufacturers directions. By laser etching the structure enamel in section was rougher. The optimal connection between the enamel and composite resin was achieved in 75 percent by acid etching and in 79.2 percent by Er:YAG laser etching. Er:YAG laser etching could be alternative method for etching of enamel.

  1. Absorption of some powder materials to YAG laser



    Laser powder alloying is widely used for tribological applications. As one of the key pa-rameters , absorptivity of powder materials to laser plays an important role in the processing. Themeasurement of laser absorptivity is essential for absorptivity research. In present work, lumpedmethod based on heat transfer is established for laser absorptivity measurement. The absorptivityof some powder materials as Cu, Fe, Al, NiO, Al2O3, ZrO2, SiC, to YAG laser, are investigated.The results show that the absorptivity of powder materials to YAG laser is generally larger thanthat of bulk materials.

  2. Pre-pumped passively Q-switched Nd:YAG/Cr:YAG microchip laser

    Xinning Tian(田信宁); Ping Yan(闫平); Qiang Liu(柳强); Mali Gong(巩马理); Yun Liao(廖云)


    A pre-pumped passively Q-switched Nd:YAG/Cr:YAG microchip laser is demonstrated with a peak power of 7.5 kW at pulse repetition rate of serveral kilohertzs. The full-width at half-maximum(FWHM)is 734 ps, and the pulse energy is 5.5 μJ with a fundamental spatial mode. In this system, the pre-pumped microchip laser of Nd:YAG/Cr:YAG wafer which is bonded through the thermal-bonding technique has achieved a time jitter value of 12 μs and a Q-switched amplitude instability of 1.26%(15)through the pre-pumped modulation technique.

  3. The bactericidal effect of a Genius (R) Nd : YAG laser

    Kranendonk, A.A.; Reijden, W.A. van der; Winkelhoff, A.J. van; Weijden, G.A. van der


    PURPOSE: To evaluate the 'in vitro' bactericidal effect of the Nd:YAG laser (Genius, MØlsgaard Dental, Copenhagen, Denmark) on six periodontal pathogens. METHODS: Suspensions of six different periodontal pathogens (Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedi

  4. The bactericidal effect of a Genius Nd: YAG laser

    Kranendonk, A.A.; van der Reijden, W.A.; van Winkelhoff, A.J.; van der Weijden, G.A.


    Purpose: To evaluate the ‘in vitro’ bactericidal effect of the Nd:YAG laser (Genius, MØlsgaard Dental, Copenhagen, Denmark) on six periodontal pathogens. Methods: Suspensions of six different periodontal pathogens (Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedi

  5. The bactericidal effect of a Genius (R) Nd : YAG laser

    Kranendonk, A.A.; Reijden, W.A. van der; Winkelhoff, A.J. van; Weijden, G.A. van der


    PURPOSE: To evaluate the 'in vitro' bactericidal effect of the Nd:YAG laser (Genius, MØlsgaard Dental, Copenhagen, Denmark) on six periodontal pathogens. METHODS: Suspensions of six different periodontal pathogens (Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedi

  6. Investigation of thermodynamic equilibrium in laser-induced aluminum plasma using the H{sub α} line profiles and Thomson scattering spectra

    Cvejić, M., E-mail:, E-mail: [Institute of Physics, University of Belgrade, P.O. Box 68, 11080 Belgrade (Serbia); Faculty of Physics, Weizmann Institute of Science, Rehovot 7610001 (Israel); Dzierżęga, K., E-mail:, E-mail:; Pięta, T. [M. Smoluchowski Institute of Physics, Jagellonian University, ul. Łojasiewicza 11, 30-348 Kraków (Poland)


    We have studied isothermal equilibrium in the laser-induced plasma from aluminum pellets in argon at pressure of 200 mbar by using a method which combines the standard laser Thomson scattering and analysis of the H{sub α}, Stark-broadened, line profiles. Plasma was created using 4.5 ns, 4 mJ pulses from a Nd:YAG laser at 1064 nm. While electron density and temperature were determined from the electron feature of Thomson scattering spectra, the heavy particle temperature was obtained from the H{sub α} full profile applying computer simulation including ion-dynamical effects. We have found strong imbalance between these two temperatures during entire plasma evolution which indicates its non-isothermal character. At the same time, according to the McWhirter criterion, the electron density was high enough to establish plasma in local thermodynamic equilibrium.

  7. 600-W lamp pumped CW Nd:YAG laser

    Qiang Li(李强); Zhimin Wang(王志敏); Zhiyong Wang(王智勇); Zhensheng Yu(于振声); Hong Lei(雷訇); Jiang Guo(郭江); Gang Li(李港); Tiechuan Zuo(左铁钏)


    A lamp pumped CW Nd:YAG laser is presented in this paper for the requirement of industrial application.The main factors, which affect output power and beam quality of high power solid-state laser module, are theoretically analyzed. Total electro-optics efficiency of lamp pumped Nd:YAG crystal as high as 4.0% is obtained, and output power is higher than 647 W with beam parameter product 22 mm.mrad.

  8. Experimental 511 W Composite Nd:YAG Ceramic Laser

    LI Hai-Feng; XU De-Gang; YANG Yang; WANG Yu-Ye; ZHOU Rui; ZHANG Tie-Li; ZHAO Xin; WANG Peng; YAO Jian-Quan


    @@ We demonstrate a 511 W laser diode pumped composite Nd:YAG ceramic laser. The optical pumping system is consisted of five laser diode stacked arrays arranged in a pentagonal shape around the ceramic rod whose size is φ6.35×144mm. When the pumping power is 1600W, the cw laser output up to 511 W at 1064nm can be obtained with a linear plano-plano cavity, and the optical-to-optical efficiency is 31.9%. To our knowledge, this is the highest value of laser output by using a newly invented composite Nd:YAG ceramic rod as the gain medium.

  9. Observation of Thomson Scattering off Entropy Waves in a Laser-Produced Plasma

    ZHENG Jian; BAI Bo; LIU Wan-Dong; YU Chang-Xuan; JIANG Xiao-Hua; YUAN Xiao-Dong; LI Wen-Hong; ZHENG Zhi-Jian


    A new feature in the Thomson scattering spectrum is observed from a laser-produced aluminium plasma, which may be the Thomson scattering off entropy waves in the plasma. Such a feature is only observable when the energy of the heater beam is low enough.

  10. Electrically Tunable Nd:YAG waveguide laser based on Graphene

    Ma, Linan; Tan, Yang; Akhmadaliev, Shavkat; Zhou, Shengqiang; Chen, Feng


    We demonstrate a tunable hybrid Graphene-Nd:YAG cladding waveguide laser exploiting the electro-optic and the Joule heating effects of Graphene. A cladding Nd:YAG waveguide was fabricated by the ion irradiation. The multi-layer graphene were transferred onto the waveguide surface as the saturable absorber to get the Q-switched pulsed laser oscillation in the waveguide. Composing with appropriate electrodes, graphene based capacitance and heater were formed on the surface of the Nd:YAG waveguide. Through electrical control of graphene, the state of the hybrid waveguide laser was turned on or off. And the laser operation of the hybrid waveguide was electrically tuned between the continuous wave laser and the nanosecond pulsed laser.

  11. Densification behavior, doping profile and planar waveguide laser performance of the tape casting YAG/Nd:YAG/YAG ceramics

    Ge, Lin; Li, Jiang; Qu, Haiyun; Wang, Juntao; Liu, Jiao; Dai, Jiawei; Zhou, Zhiwei; Liu, Binglong; Kou, Huamin; Shi, Yun; Wang, Zheng; Pan, Yubai; Gao, Qingsong; Guo, Jingkun


    The sintering behavior and doping concentration profile of the planar waveguide YAG/Nd:YAG/YAG ceramics by the tape casting and solid-state reaction method were investigated on the basis of densification trajectory, microstructure evolution, and Nd3+ ions diffusion. The porosity of the green body by tape casting and cold isostatic pressing is about 38.6%. And the green bodies were consolidated from 1100 °C to 1800 °C for 0.5-20 h to study the densification and the doping diffusion behaviors. At the temperature higher than 1500 °C, pure YAG phase is formed, followed by the densification and grain growth process. With the increase of temperature, two sintering stages occur, corresponding to remarkable densification and significant grain growth, respectively. The mechanism controlling densification at 1550 °C is grain boundary diffusion. The diffusion of Nd3+ ions is more sensitive to temperature than the sintering time, and the minimum temperature required for the obvious diffusion of Nd3+ ions is higher than 1700 °C. Finally, planar waveguide YAG/1.5 at.%Nd:YAG/YAG transparent ceramics with in-line transmittance of 84.8% at 1064 nm were obtained by vacuum-sintering at 1780 °C for 30 h. The fluorescence lifetime of 4F3/2 state of Nd3+ in the specimen is about 259 μs. The prepared ceramic waveguide was tested in a laser amplifier and the laser pulse was amplificated from 87 mJ to 238 mJ, with the pump energy of 680 mJ.

  12. Operation and beam profiling of an up to 200 kHz pulse-burst laser for Thomson scattering

    Young, W. C., E-mail:; Den Hartog, D. J. [Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)


    A new, high-repetition rate laser is in development for use on the Thomson scattering diagnostic on the Madison Symmetric Torus. The laser has been tested at a rate of 200 kHz in a pulse-burst operation, producing bursts of 5 pulses above 1.5 J each, while capable of bursts of 17 pulses at 100 kHz. A master oscillator-power amplifier architecture is used with a Nd:YVO{sub 4} oscillator, four Nd:YAG amplifiers, and a Nd:glass amplifier. A radial profile over the pulse sequence is measured by using a set of graphite apertures and an energy meter, showing a change in beam quality over a pulsing sequence.

  13. Simultaneous measurement of electron and heavy particle temperatures in He laser-induced plasma by Thomson and Rayleigh scattering

    Dzierzega, K.; Mendys, A.; Zawadzki, W. [Marian Smoluchowski Institute of Physics, Jagiellonian University, ul. Reymonta 4, 30-059 Krakow (Poland); Pokrzywka, B. [Mt. Suhora Observatory, Pedagogical University of Cracow, ul. Podchorazych 2, 30-084 Krakow (Poland); Pellerin, S. [GREMI, site de Bourges, Universite d' Orleans, CNRS, rue Gaston Berger BP 4043, 18028 Bourges (France)


    Thomson and Rayleigh scattering methods were applied to quantify the electron and heavy particle temperatures, as well as electron number density, in a laser spark in helium at atmospheric pressure. Plasma was created using 4.5 ns, 25 mJ pulses from Nd:YAG laser at 532 nm. Measurements, performed for the time interval between 20 ns and 800 ns after breakdown, show electron density and temperature to decrease from 7.8 Multiplication-Sign 10{sup 23} m{sup -3} to 2.6 Multiplication-Sign 10{sup 22} m{sup -3} and from 95 900 K to 10 350 K, respectively. At the same time, the heavy particle temperature drops from only 47 000 K down to 4100 K which indicates a two temperature plasma out of local isothermal equilibrium.

  14. Clinical application of erbium:YAG laser in periodontology.

    Ishikawa, Isao; Aoki, Akira; Takasaki, Aristeo Atsushi


    Various lasers have been introduced for the treatment of oral diseases and their applications in dental clinics have become a topic of much interest among practitioners. Technological advances and improvements have increased the choices of the available laser systems for oral use. Among them, a recently developed erbium-doped:yttrium aluminum garnet (Er:YAG) laser system possesses suitable characteristics for oral soft and hard tissue ablation. Due to its high absorption in water, an effective ablation with a very thin surface interaction occurs on the irradiated tissues without any major thermal damage to the irradiated and surrounding tissues. In the field of periodontics, the application of Er:YAG laser for periodontal hard tissue has begun with studies from Japanese and German researchers. Several in vitro and clinical studies have already demonstrated an effective application of the Er:YAG laser for calculus removal and decontamination of the diseased root surface in periodontal non-surgical and surgical procedures. However, further studies are required to better understand the various effects of Er:YAG laser irradiation on biological tissues for its safe and effective application during periodontal and implant therapy. Randomized controlled clinical trials and more basic studies have to be encouraged and performed to confirm the status of Er:YAG laser treatment as an adjunct or alternative to conventional mechanical periodontal therapy. In this paper, the advantages and current clinical applications of this laser in periodontics and implant dentistry are summarized based on current scientific evidence.

  15. Nd:YAG Laser Posterior Capsulotomy and Visual Outcome

    Khaleda Nazneen Bari


    Full Text Available Background: Neodymium-doped yttrium aluminum garnet (Nd:YAG laser capsulotomy is a relatively noninvasive procedure that is used in the treatment of posterior capsular opacification (PCO. PCO is caused by proliferation of lens epithelial cells which causes fibrotic changes and wrinkling of the posterior capsule and results in decreased vision, glare, and other symptoms similar to that of the original cataract.Objective: To find out the visual outcome after performing Nd:YAG laser capsulotomy for PCO.Materials and method: A prospective clinical trial was carried out in National Institute of Ophthalmology (NIO, Dhaka, Bangladesh from January 2010 to June 2011 on purposively selected 70 adult subjects of both sexes who developed PCO within 2 months to more than 2 years after extracapsular cataract extraction with posterior chamber intra ocular lens implant. After thorough pre laser assessment Nd:YAG laser capsulotomy was carried out with Zeis VISULAS YAG II through Zeiss slit lamp under topical anesthesia. Data were recorded and expressed as proportion.Results: Out of the 70 subjects 40 were male and 30 were female. The average time interval of cataract surgery and Nd: YAG laser capsulotomy was 23 months. Capsular fibrosis (57.04% was the predominant type of PCO. The pre laser visual acuity (VA of more than 61.06% of eyes was 6/36 or below while 41.12% had VA hand movements to finger count. After Nd:YAG laser capsulotomy VA of 6/18 or better was achieved in 63.9% of eyes while 9.94% recovered to 6/9 and 11.36% achieved 6/6. None of these eyes showed further deterioration in VA.Conclusion: Nd:YAG laser capsulotomy for PCO is safe, effective and a rewarding procedure for improvement of vision.

  16. 21 CFR 886.4392 - Nd:YAG laser for posterior capsulotomy and peripheral iridotomy.


    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nd:YAG laser for posterior capsulotomy and...:YAG laser for posterior capsulotomy and peripheral iridotomy. (a) Identification. The Nd:YAG laser for... laser intended for disruption of the posterior capsule or the iris via optical breakdown. The...

  17. Er:YAG laser debonding of porcelain veneers

    Buu, Natalie; Morford, Cynthia; Finzen, Frederick; Sharma, Arun; Rechmann, Peter


    The removal of porcelain veneers using Er:YAG lasers has not been previously described in the scientific literature. This study was designed to systematically investigate the efficacy of an Er:YAG laser on veneer debonding without damaging the underlying tooth structure, as well as preserving a new or misplaced veneer. Initially, Fourier Transform Infrared Spectroscopy (FTIR) was used on flat porcelain veneer samples (IPS Empress Esthetic; Ivoclar Vivadent, Amherst, NY) to assess which infrared laser wavelengths are transmitted through the veneer. Additionally, FTIR spectra from a veneer bonding cement (RelyX Veneer Cement A1; 3M ESPE, St. Paul, MN) were obtained. While the veneer material showed no characteristic water absorption bands in the FTIR, the bonding cement has a broad H2O/OH absorption band coinciding with the ER:YAG laser emission wavelength. Consequently Er:YAG laser energy transmission through different veneer thicknesses was measured. The porcelain veneers transmitted 11 - 18 % of the incident Er:YAG laser energy depending on their thicknesses (Er:YAG laser: LiteTouch by Syneron; wavelength 2,940 nm, 10 Hz repetition rate, pulse duration 100 μs at 133 mJ/pulse; straight sapphire tip 1,100 μm diameter; Syneron, Yokneam, Israel). Initial signs of cement ablation occurred at approximately 1.8 - 4.0 J/cm2. This can be achieved by irradiating through the veneer with the fiber tip positioned at a distance of 3-6 mm from the veneer surface, and operating the Er:YAG laser with 133 mJ output energy. All eleven veneers bonded on extracted anterior incisor teeth were easily removed using the Er:YAG laser. The removal occurred without damaging underlying tooth structure as verified by light microscopic investigation (Incident Light Microscope Olympus B 50, Micropublisher RTV 3.3 MP, Image Pro software, Olympus). The debonding mainly occurred at the cement/veneer interface. When the samples were stored in saline solution for 5 days and/or an air-waterspray was

  18. Focussing effects in laser-electron Thomson scattering

    Harvey, C; Holkundkar, A R


    We study the effects of laser pulse focussing on the spectral properties of Thomson scattered radiation. Modelling the laser as a paraxial beam we find that, in all but the most extreme cases of focussing, the temporal envelope has a much bigger effect on the spectrum than the focussing itself. For the case of ultra-short pulses where the paraxial model is no longer valid, we adopt a sub-cycle vector beam description of the field. It is found that the emission harmonics are blue shifted and broaden out in frequency space as the pulse becomes shorter. Additionally the carrier envelope phase becomes important, resulting in an angular asymmetry in the spectrum. We then use the same model to study the effects of focussing beyond the limit where the paraxial expansion is valid. It is found that fields focussed to sub-wavelength spot sizes produce spectra that are qualitatively similar to those from sub-cycle pulses due to the shortening of the pulse with focussing. Finally, we study high-intensity fields and find ...

  19. Cryogenic Tm: YAG Laser in the Near Infrared


    REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER (DOUBLE-CLICK HERE TO EDIT) < Cryogenic Tm:YAG Laser in the Near Infrared* Tso Yee Fan...therefore limits operation. However, operation at cryogenic temperature depopulates the lower laser level, reduces laser threshold, increases...efficiency, and greatly mitigates thermo-optic effects in crystalline host materials [21]-[23]. Here, we have used cryogenic cooling to enable laser

  20. Experimental study of thermal lensing of Nd:YAG laser

    HU Shao-yun; ZHONG Ming; ZUO Yan; FAN Hong-ying


    A wavefront method of measuring the thermal lensing of solid-state lasers is proposed.This method is easy to implement and has a high spatial resolution for diagnosing thermal lensing.By this method,the thermal lensing of Nd:YAG laser is studied in detail.And this work provides a means for studying the thermal effects of laser medium and many instructional parameters for optimizing the design of the laser cavity.

  1. Dichroic mirror for diode pumped YAG:Nd-laser

    Dinca, Andreea; Skettrup, Torben; Lupei, V.


    The paper describes the design and realization of a dichroic mirror for a diode pumped YAG:Nd laser. The mirror is deposed on an optical glass substrate and works in optical contact with the laser crystal. The design was performed by admittance matching of the basic stack with the adjacent media...

  2. Thomson Scattering Process in Laser-Produced Plasmas

    YU Quan-Zhi; JIANG Xiao-Hua; LI Wen-Hong; LIU Shen-Ye; ZHENG Zhi-Jian; ZHANG Jie; LI Yu-Tong; ZHENG Jun; YAN Fei; LU Xin; WANG Zhe-Bin; ZHENG Jian; YU Chang-Xuan


    @@ We present the evolutions of the electron temperature and plasma expansion velocity with Thomson scattering experiment. The observed time-resolved ion-acoustic image is reproduced by a numerical code which couples the Thomson scattering theory with the output parameters of the one-dimensional hydrocode MEDUSA.

  3. Combined effect of fluoride varnish to Er:YAG or Nd:YAG laser on permeability of eroded root dentine.

    Chiga, Sandra; Toro, Carmen Victoria Torres; Lepri, Taísa Penazzo; Turssi, Cecília Petroso; Colucci, Vivian; Corona, Silmara Aparecida Milori


    This study evaluated the combined effect of fluoride varnish to Er:YAG or Nd:YAG laser on permeability of eroded root dentine. Sixty slabs of bovine root dentine (2×2×2mm) were eroded with citric acid 0.3% (pH 3.2) during 2h and then kept in artificial saliva during 24h. Specimens were randomly assigned in 6 groups (n=10), to receive the following treatments: fluoride varnish; fluoride varnish+Er:YAG laser; fluoride varnish+Nd:YAG laser; non-fluoride varnish; non-fluoride varnish+Er:YAG laser; non-fluoride varnish+Nd:YAG laser. The Er:YAG (100mJ, 3Hz) and Nd:YAG (70mJ, 15Hz) were applied for 10s. Specimens were subjected to further erosive challenges with citric acid 0.3% 4×/day, during 1min, for 5 days, remaining in artificial saliva between cycles. Dentin permeability was then assessed. Two-way ANOVA demonstrated no significant interaction between laser and varnish (p=0.858). No effect was also detected for the main factor varnish (p=0.768), while permeability of eroded root dentin was significantly lower when such substrate was laser-irradiated, no matter the laser source (pfluoride varnish application. Copyright © 2016. Published by Elsevier Ltd.

  4. Identification and mitigation of stray laser light in the Thomson scattering system on the Madison Symmetric Torus (MST)

    Jacobson, C. M., E-mail:; Borchardt, M. T.; Den Hartog, D. J.; Falkowski, A. F.; Morton, L. A.; Thomas, M. A. [Department of Physics, University of Wisconsin–Madison, 1150 University Avenue, Madison, Wisconsin 53706 (United States)


    The Thomson scattering diagnostic on the Madison Symmetric Torus (MST) records excessive levels of stray Nd:YAG laser light. Stray light saturates the 1064 nm spectral channel in all polychromators, which prevents absolute electron density measurements via Rayleigh scattering calibration. Furthermore, stray light contaminates adjacent spectral channels for r/a ≥ 0.75, which renders the diagnostic unable to make electron temperature measurements at these radii. In situ measurements of stray light levels during a vacuum vessel vent are used to identify stray light sources and strategies for reduction of stray light levels. Numerical modeling using Zemax OpticStudio supports these measurements. The model of the vacuum vessel and diagnostic includes synthetic collection optics to enable direct comparison of measured and simulated stray light levels. Modeling produces qualitatively similar stray light distributions to MST measurements, and quantifies the mitigation effects of stray light mitigation strategies prior to implementation.

  5. Identification and mitigation of stray laser light in the Thomson scattering system on the Madison Symmetric Torus (MST)

    Jacobson, C. M.; Borchardt, M. T.; Den Hartog, D. J.; Falkowski, A. F.; Morton, L. A.; Thomas, M. A.


    The Thomson scattering diagnostic on the Madison Symmetric Torus (MST) records excessive levels of stray Nd:YAG laser light. Stray light saturates the 1064 nm spectral channel in all polychromators, which prevents absolute electron density measurements via Rayleigh scattering calibration. Furthermore, stray light contaminates adjacent spectral channels for r/a ≥ 0.75, which renders the diagnostic unable to make electron temperature measurements at these radii. In situ measurements of stray light levels during a vacuum vessel vent are used to identify stray light sources and strategies for reduction of stray light levels. Numerical modeling using Zemax OpticStudio supports these measurements. The model of the vacuum vessel and diagnostic includes synthetic collection optics to enable direct comparison of measured and simulated stray light levels. Modeling produces qualitatively similar stray light distributions to MST measurements, and quantifies the mitigation effects of stray light mitigation strategies prior to implementation.

  6. Scaling and passively Q-switch operation of a Nd:YAG laser pumped laterally through a YAG prism

    Dascalu, T.; Salamu, G.; Sandu, O.; Dinca, M.; Pavel, N.


    We report on scaling of a laser configuration in which a YAG prism is used to couple the pump beam from a fiber-coupled diode laser directly into a Nd:YAG medium. Several resonator geometries have been investigated. In free generation regime laser pulses at 1.06 μm with energy of 22.1 mJ for the pump energy of 44.6 mJ were obtained from a 10.0 mm long, 1.0-at% Nd:YAG single crystal that had the high-reflectivity mirror coated directly on one of the laser crystal surface. The slope efficiency was 0.51. A similar uncoated Nd:YAG crystal placed in a plane-plane resonator delivered laser pulses with 17.8 mJ energy under the pump with 45.4 mJ energy, at 0.40 slope efficiency. Further, a passively Q-switched Nd:YAG/Cr4+:YAG composite ceramic laser pumped through a YAG prism has been built. Using a Cr4+:YAG saturable absorber of 0.85 initial transmission the device delivered laser pulses with 0.29 mJ energy and 11 ns duration. The output performances are compared to those obtained in a classical end-pumping scheme.

  7. Cutting of nonmetallic materials using Nd:YAG laser beam

    Bashir Ahmed Tahir; Rashid Ahmed; M. G. B. Ashiq; Afaq Ahmed; M. A. Saeed


    This study deals with Nd:YAG laser cutting nonmetallic materials,which is one of the most important and popular industrial applications of laser.The main theme is to evaluate the effects of Nd:YAG laser beam power besides work piece scanning speed.For approximate cutting depth,a theoretical study is conducted in terms of material property and cutting speed.Results show a nonlinear relation between the cutting depth and input energy.There is no significant effect of speed on cutting depth with the speed being larger than 30 mm/s.An extra energy is utilized in the deep cutting.It is inferred that as the laser power increases,cutting depth increases.The experimental outcomes are in good agreement with theoretical results.This analysis will provide a guideline for laser-based industry to select a suitable laser for cutting,scribing,trimming,engraving,and marking nonmetallic materials.


    A. M. Ivashko


    Full Text Available The theoretical and experimental results of longitudinally continuous-wave diode-pumped Yb:Y3Al5O12 (YAG laser performance for compact field-condition measuring systems were demonstrated. Optimization of laser setup in terms of operation condition in the range of -40 ˚С – +65 ˚С without active thermal stabilization was carried out. Using Yb (10 ат.%:YAG crystal with the length of 3 mm the maximal output power more than 2 W was obtained in the whole of temperature range.

  9. Holmium:YAG laser coronary angioplasty in acute myocardial infarction

    Topaz, On; Luxenberg, Michael; Schumacher, Audrey


    Patients who sustain complicated acute myocardial infarction in whom thrombolytic agents either fail or are contraindicated often need mechanical revascularization other than PTCA. In 24 patients with acute infarction complicated by continuous chest pain and ischemia who either received lytics or with contraindication to lytics, a holmium:YAG laser (Eclipse Surgical Technologies, Palo Alto, CA) was utilized for thrombolysis and plaque ablation. Clinical success was achieved in 23/24 patients, with 23 patients (94%) surviving the acute infarction. Holmium:YAG laser is very effective and safe in thrombolysis and revascularization in this complicated clinical setting.

  10. 340 W average power output of diode-pumped composite ceramic YAG/Nd:YAG disk laser

    Jia, Kai; Jiang, Yong; Yang, Feng; Deng, Bo; Hou, Tianjin; Guo, Jiawei; Chen, Dezhang; Wang, Hongyuan; Yang, Chuang; Peng, Chun


    We report on a diode-pumped composite ceramic disk laser in this paper. The composite ceramic YAG/Nd:YAG disk consists of 4 mm thick pure YAG and 2 mm thick Nd:YAG with 1.0 at.% doping concentration. The slope efficiency of the composite ceramic disk laser is 36.6% corresponding to the maximum optical-optical efficiency of 29.2%. Furthermore, 340 W average power output was achieved at the absorbed pump power of 1290 W.

  11. Neodymium YAG Lasers. Citations from the NTIS data base

    Carrigan, B.


    Federally funded research reports on lasing of neodymium doped yttrium aluminum garnet are cited. Studies on design, fabrication, quantum efficiency, light pulses, stabilization, and testing are covered. Optical pumping, mode locking, frequency conversion, and modulation of these lasers are discussed. Laser applications such as optical communication, range finding, and tracking are included. Safety hazards and radiation damage related to neodymium YAG lasers are also covered. This updated bibliography contains 181 citations, 15 of which are new entries to the previous edition.

  12. Diode-pumped 1123-nm Nd:YAG laser

    Xiaoping Guo(郭晓萍); Meng Chen(陈檬); Gang Li(李港); Bingyuan zhang(张炳元); Jiandong Yang(杨建东); Zhigang Zhang(张志刚); Yonggang Wang(王勇刚)


    We demonstrated a diode-pumped Nd:YAG laser with a plano-concave resonator. When the pump power is 1.57 W, the output power of 1123-nm laser is 132 mW at the temperature of 20 ℃, and the power change is less than 2% in an hour. A periodically poled LiNbOa (PPLN) was used as outer cavity frequency-doubling crystal and 561-nm laser was observed.

  13. Development behavior of liquid plasma produced by YAG laser

    Yamada, J; Yamada, Jun; Tsuda, Norio


    The laser induced plasma in liquid hasn't been studied enough. In liquid, the laser induced plasma may be able to resolve the hazardous material called the environment material. Then, the plasma produced in liquid by the laser light is studied and the plasma development is observed by a streak camera. The ultra pure water or the ultra pure water with a melted NaCl is used as a test liquid. The liquid plasma is produced by the fundamental wave of YAG laser. When NaCl concentration is varied, the plasma development behavior is obserbed by streak camera. The liquid plasma develops backward. The plasma is produced from many seeds and It consists of a group of plasmas. However, the liquid plasma produced by second harmonic wave of YAG laser develops as a single plasma. The development mechanism is investigated from the growth rate of backward plasma. The backward plasma develops by breakdown wave and radiation supported shock wave.

  14. Investigations of YAG:Er(3+),Yb(3+) and YAG:Co(2+) Crystals for Laser Applications


    doped YAG crystals are given. Erbium and ytterbium doped YAG single crystals were obtained by the Czochralski method . The spectral properties and laser...relaxation time of 290 Rts14 2. CRYSTAL GROWTH The crystals were obtained by the Czochralski method , using iridium crucibles of external dimensions...YAG:Co 2+ single crystal grown by Czochralski method is presented. In all obtained crystals the core area of the characteristic threefold symmetry was

  15. The possibility of clinical application of the solid state lasers: Nd:YAG, Ho:YAG, and Er:YAG in otolaryngology - head and neck surgery

    Tomaszewska, M.; Kukwa, A.; Tulibacki, M.; Wójtowicz, P.; Olędzka, I.; Jeżewska, E.


    The purpose of this study was to summarize our experiences in clinical application of Nd:YAG, Ho:YAG and Er:YAG in otolaryngology- head and neck surgery. Choosing the laser type and parameters for the particular procedures was based on our previous research on tissue effects of those lasers. During the period of 1993-2006 we performed 3988 surgical procedures with the Nd:YAG laser. Over 87% of those were made for the nasal cavity pathologies as polyps, hyperplasia of inferior nasal turbinate, granulation tissue, postoperative adhesions, vascular malformations, under the local anesthesia conditions. In our experience Nd:YAG laser gives the possibility of good clinical control and low risk of side effects for disorders of high recurrence and frequent interventions necessity, as nasal polyps or respiratory papillomatosis. Nd:YAG assisted uvulopalatoplasty gives an interesting alternative for surgical procedures for snoring and slight/mild OSA-recognized patients. Due to its good hemostatic properties, it is a perfect tool for removal of the chemodectoma from meddle ear. During the period of 1995-2006 we performed 229 surgical procedures with the Ho:YAG laser, mostly for larynx pathologies (adhesion and scar tissue removal). In our experience Ho:YAG laser can serve as a precise laser knife for both soft and bony tissue. The ER:YAG laser still remain under clinical trial. Since 2001 year we performed 24 procedures of removing stone deposits from salivary glands. We believe it may become a promising method to cope with sialolithiasis which allows for glandule function preservation. All of the laser types mentioned above, can be easily coupled with endoscopes, what makes them available for all of the head and necklocalized disorders.

  16. Laser-assisted hair transplantation: histologic comparison between holmium:YAG and CO2 lasers

    Chu, Eugene A.; Rabinov, C. Rose; Wong, Brian J.; Krugman, Mark E.


    The histological effects of flash-scanned CO2 (λ=10.6μm) and pulsed Holmium:YAG (Ho:YAG, λ=2.12μm) lasers were evaluated in human scalp following the creation of hair transplant recipient channels. Ho:YAG laser irradiation created larger zones of thermal injury adjacent to the laser channels than irradiation with the CO2 laser device. When the two lasers created recipient sites of nearly equal depth, the Holmium:YAG laser caused a larger region of lateral thermal damage (589.30μm) than the CO2 laser (118.07μm). In addition, Holmium:YAG irradiated specimens exhibited fractures or discontinuities beyond the region of clear thermal injury. This shearing effect is consistent with the photoacoustic mechanism of ablation associated with pulsed mid-IR laser irradiation. In contrast, channels created with the CO2 exhibited minimal epithelial disruption and significantly less lateral thermal damage. While the Holmium:YAG laser is a useful tool for ablation soft tissue with minimal char in select applications (sinus surgery, arthroscopic surgery), this study suggests that the use of the CO2 laser for the creation of transplantation recipient channels result in significantly less lateral thermal injury for the laser parameters employed.

  17. Effects of Er:YAG laser irradiation on human cartilage

    Glinkowski, Wojciech; Brzozowska, Malgorzata; Ciszek, Bogdan; Rowinski, Jan; Strek, Wieslaw


    Irradiation of the hyaline or fibrous cartilage excised from the body of a human cadaver with Er:YAG laser beam, single pulse with a dose of 1 J, produces a crater with a depth of approximately 500 micrometers and a diameter varying from 5 to 300 micrometers. Histological examination has revealed that the laser-made craters were surrounded by a thin rim (2-10 micrometer) of charred and coagulated tissue. No damage was observed in the cartilage surrounding the rim. The presence of sharp demarcation between the tissue areas ablated by laser energy and the undamaged areas argues for the potential usefulness of the Er:YAG laser in surgery of cartilages.

  18. Transient absorption and laser output of YAG : Nd

    Kvapil, Jiří; Kvapil, Jos; Kubelka, J.; Kubeček, V.


    YAG : Nd grown under 98% Ar 2% H2 protective atmosphere free of nitrogen or hydrocarbons showed after UV irradiation broad absorption peaked at ˜1·9×104 cm-1 which disappeared relatively slowly at room temperature. It was more intensive in oxygen treated samples than in those annealed in hydrogsn. Transient absorption suppresses laser output by the increase of absorption at 0·94×104 cm-1 (1064 nm) and, particularly in CW mode, by the anomalous rod deformation. YAG : Nd containing Fe ions (≲2·10-4 wt%) showed no transient absorption.

  19. Highly efficient Nd: YAG ceramic CW laser with 59.8% slope-efficiency

    Yunfeng Qi; Qihong Lou; Haixia Ma; Jingxing Dong


    @@ In this paper, a highly efficient Ti:sapphire end-pumped 1 at.-% Nd:YAG ceramic laser that is comparable in efficiency with Nd:YAG single crystal lasers has been developed. Optical absorption and emission spectra for Nd:YAG ceramics have been measured. With 673-mW pumping, 295-mW laser output at 1064 nm has been obtained. The laser threshold is only 13 mW. Deducted the transmitted light, the corresponding optical-to-optical conversion efficiency is 58.4%. The lasing characteristics of Nd:YAG ceramic are nearly equal to those of Nd:YAG single crystal.

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

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


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

  1. Ablation of porcine ligamentum flavum with Ho:YAG, q-switched Ho:YAG, and quadrupled Nd:YAG lasers.

    Johnson, Matt R; Codd, Patrick J; Hill, Westin M; Boettcher, Tara


    Ligamentum flavum (LF) is a tough, rubbery connective tissue providing a portion of the ligamentous stability to the spinal column, and in its hypertrophied state forms a significant compressive pathology in degenerative spinal stenosis. The interaction of lasers and this biological tissue have not been thoroughly studied. Technological advances improving endoscopic surgical access to the spinal canal makes selective removal of LF using small, flexible tools such as laser-coupled fiber optics increasingly attractive for treatment of debilitating spinal stenosis. Testing was performed to assess the effect of Ho:YAG, Q-switched Ho:YAG, and frequency quadrupled Nd:YAG lasers on samples of porcine LF. The objective was to evaluate the suitability of these lasers for surgical removal of LF. LF was resected from porcine spine within 2 hours of sacrifice and stored in saline until immediately prior to laser irradiation, which occurred within an additional 2 hours. The optical absorbance of a sample was measured over the spectral band from 190 to 2,360 nm both before and after dehydration. For the experiments using the Ho:YAG (λ = 2,080 nm, tp  = 140 µs, FWHM) and Q-Switched Ho:YAG (λ = 2,080 nm, tp  = 260 ns, FWHM) lasers, energy was delivered to the LF through a laser-fiber optic with 600 µm core and NA = 0.39. For the experiment using the frequency quadrupled Nd:YAG laser (λ = 266 nm, tp  = 5 ns FWHM), rather than applying the laser energy through a laser-fiber, the energy was focused through an aperture and lens directly onto the LF. Five experiments were conducted to evaluate the effect of the given lasers on LF. First, using the Ho:YAG laser, the single-pulse laser-hole depth versus laser fluence was measured with the laser-fiber in direct contact with the LF (1 g force) and with a standoff distance of 1 mm between the laser-fiber face and the LF. Second, with the LF remaining in situ and the spine bisected

  2. Ho:YAG laser arthroscopy of the knee

    Sisto, Domenick J.; Blazina, Martin E.; Hirsh, Linda C.


    The HO:YAG laser is a near-contact laser with a capacity to ablate or cut tissues. The ablation function allows the surgeon to remove meniscal tissue, lyse and resect adhesions, melt loose bodies, and dissolve inflamed synovium. The cutting function of the laser is utilized to perform a lateral release or resect torn menisci. The laser can also be utilized to drill holes in Grade IV chondromalacic lesions to initiate a healing response. The laser has been embraced by orthopaedic surgeons because of its shape and versatility. The tip is only 2 mm wide and can be delivered into the tight posterior compartments of the knee with no damaging contact with the articular surfaces. The laser coagulates as it works and bleeding is minimized. The laser can function both as a cutting and ablating tool. The laser can also drill holes into subchondral bone to, hopefully, initiate a healing response.

  3. Optodynamic analysis of pulsed-laser processing with a Nd:YAG laser

    Strgar, Simon; Možina, Janez


    Laser drilling and laser marking of metals with a pulsed Nd:YAG laser are discussed. Some characteristics of pulsed-laser processing and the possibilities of process optodynamic analysis are presented for the laser-drilling of aluminium. The optodynamic analysis is based on observation of generated shock waves, which propagate in the material as well as in the surrounding air during laser processing. For the detection of laser-induced shock waves in the air and for measurements of their chara...

  4. Pulsed Tm:YAG laser ablation of knee joint tissues

    Shi, Wei-Qiang; Vari, Sandor G.; Duffy, J. T.; Miller, J. M.; Weiss, Andrew B.; Fishbein, Michael C.; Grundfest, Warren S.


    We investigated the effect of a free-running 2.01 micron pulsed Tm:YAG laser on bovine knee joint tissues. Ablation rates of fresh fibrocartilage, hyaline cartilage, and bone were measured in saline as a function of laser fluence (160 - 640 J/cm2) and fiber core size (400 and 600 microns). All tissues could be effectively ablated and the ablation rate increased linearly with the increasing fluence. Use of fibers of different core sizes, while maintaining constant energy fluence, did not result in significant difference in ablation rate. Histology analyses of the ablated tissue samples reveal average Tm:YAG radiation induced thermal damage (denatunalization) zones ranging between 130 and 540 microns, depending on the laser parameters and the tissue type.

  5. Bactericidal effect of Nd:YAG laser irradiation in endodontics

    Aun, Carlos E.; Barberini, Alexandre F.; Camargo, Selma C. C.; Silva Kfouri, Luciana; Lorenzetti Simionato, Maria R.


    The success of endodontic therapy is based on the elimination of bacterial colonization from the endodontic system and periapical tissues. Recent studies have been showing the bactericidal effect of laser in root canal treatment. The propose of the study is to evaluate the effect of Nd:YAG laser irradiation in contaminated root canal treatment. The propose of the study is to evaluate the effect of Nd:YAG laser irradiation in contaminated root canals from upper central incisor. For the experiment 12 teeth were selected, respect at the apical third, sterilized, and 10 μm Streptococcus sanguis liquid culture were inoculated in the root canals. The laser test groups were irradiated with Nd:YAG laser at standard setting of 15Hz, 100mj and 1,5 W for 10, 20 and 30 seconds each in slow helicoidal movements from the apex to the top using a 300 micrometers fiber. After the procedure the specimens were placed in Tryptic Soy Agar, the number of colony forming units was evaluated. The experiment showed a significant reduction on viability of Streptococcus sanguis at the respective time of 20 and 30 seconds.

  6. Development of monolith Nd:YAG /Cr+4:YAG passively Q-switched microchip laser

    Izhnin, Ihor; Vakiv, Mykola; Izhnin, Aleksandr; Syvorotka, Igor; Ubizskii, Sergii; Syvorotka, Ihor, Jr.


    The main features of passively Q-switched microchip lasers development are considered. The active medium of laser is an epitaxial structure combining an epitaxial layer of saturable absorber Cr4+:Y3Al5O12 (Cr:YAG) grown on substrate of generating crystal Nd:YAG by liquid phase epitaxy. The modulator layer has an initial optical absorption of 36 cm-1 at wavelength of lasing (1064 nm). The epitaxial layer grown on unworking side was mechanically removed and this substrate side was optically polished. The other one was processed precisely to needed thickness. The cavity's mirrors were deposited by electron beam technique directly on each side of the structure to form a rugged, monolithic resonator. Diode laser Model ATC-C4000 with lasing wavelength 808 nm provided the CW end pumping. The output pulses parameters were investigated by means of test bench consisting of photoelectric transducer FEK-15 and Digital Phosphor Oscilloscope TDS 5052B. The obtained laser parameter are as follows: pulse width (FWHM) about 1.3 ns, repetition rate 5.5 kHz, average output power about 10 mW, pulse energy 1.0 μJ, pick power 1.2 kW. The possible solutions for laser parameter improving and optimization are discussed.

  7. Clinical application of the Nd-YAG and Ho-YAG lasers in otolaryngology: head and neck surgery

    Kukwa, Andrzej; Tulibacki, Marek P.; Dudziec, Katarzyna; Wojtowicz, Piotr


    The authors present their clinical experience regarding the possibilities of application of Nd:YAG and Ho:YAG lasers for the treatment of disorders in the area of the upper respiratory tract sinuses and ears. This technique makes it possible to perform a number of procedures in local anesthesia which considerably improves the economic effectiveness of the treatment. In case of the Nd:YAG laser they have also utilized the effect of deep coagulation of the soft tissues, whereas the Ho:YAG laser energy was applied for the surgery of bone tissue. The surgeries performed using laser beam enabled very good effect of treatment. They are competitive compared wit the methods used by traditional surgery.

  8. Tissue damage by laser radiation: an in vitro comparison between Tm:YAG and Ho:YAG laser on a porcine kidney model.

    Huusmann, Stephan; Wolters, Mathias; Kramer, Mario W; Bach, Thorsten; Teichmann, Heinrich-Otto; Eing, Andreas; Bardosi, Sebastian; Herrmann, Thomas R W


    The understanding of tissue damage by laser radiation is very important for the safety in the application of surgical lasers. The objective of this study is to evaluate cutting, vaporization and coagulation properties of the 2 µm Tm:YAG laser (LISA Laser Products OHG, GER) in comparison to the 2.1 µm Ho:YAG laser (Coherent Medical Group, USA) at different laser power settings in an in vitro model of freshly harvested porcine kidneys. Laser radiation of both laser generators was delivered by using a laser fiber with an optical core diameter of 550 µm (RigiFib, LISA Laser GER). Freshly harvested porcine kidneys were used as tissue model. Experiments were either performed in ambient air or in aqueous saline. The Tm:YAG laser was adjusted to 5 W for low and 120 W for the high power setting. The Ho:YAG laser was adjusted to 0.5 J and 10 Hz (5 W average power) for low power setting and to 2.0 J and 40 Hz (80 W average power) for high power setting, accordingly. The specimens of the cutting experiments were fixed in 4 % formalin, embedded in paraffin and stained with Toluidin blue. The laser damage zone was measured under microscope as the main evaluation criteria. Laser damage zone consists of an outer coagulation zone plus a further necrotic zone. In the ambient air experiments the laser damage zone for the low power setting was 745 ± 119 µm for the Tm:YAG and 614 ± 187 µm for the Ho:YAG laser. On the high power setting, the damage zone was 760 ± 167 µm for Tm:YAG and 715 ± 142 µm for Ho:YAG. The incision depth in ambient air on the low power setting was 346 ± 199 µm for Tm:YAG, 118 ± 119 µm for Ho:YAG. On the high power setting incision depth was 5083 ± 144 µm (Tm:YAG) and 1126 ± 383 µm (Ho:YAG) respectively. In the saline solution experiments, the laser damage zone was 550 ± 137 µm (Tm:YAG) versus 447 ± 65 µm (Ho:YAG), on the low power setting and 653 ± 137 µm (Tm:YAG) versus 677 ± 134 µm (Ho:YAG

  9. Transmission of Er:YAG laser through different dental ceramics.

    Sari, Tugrul; Tuncel, Ilkin; Usumez, Aslihan; Gutknecht, Norbert


    The aim of this study was to determine the erbium-doped yttrium aluminum garnet (Er:YAG) laser transmission ratio through different dental ceramics with different thicknesses. Laser debonding procedure of adhesively luted all-ceramic restorations is based on the transmission of laser energy through the ceramic and the ablation of resin cement, because of the transmitted laser energy. Five different dental ceramics were evaluated in this study: sintered zirconium-oxide core ceramic, monolithic zirconium-oxide ceramic, feldspathic ceramic, leucite-reinforced glass ceramic, and lithium disilicate-reinforced glass ceramic. Two ceramic discs with different thicknesses (0.5 and 1 mm) were fabricated for each group. Ceramic discs were placed between the sensor membrane of the laser power meter and the tip of the contact handpiece of an Er:YAG laser device with the aid of a custom- made acrylic holder. The transmission ratio of Er:YAG laser energy (500 mJ, 2 Hz, 1 W, 1000 μs) through different ceramic discs was measured with the power meter. Ten measurements were made for each group and the results were analyzed with two way analysis of variance (ANOVA) and Tukey honestly significant difference (HSD) tests. The highest transmission ratio was determined for lithium disilicate-reinforced ceramic with 0.5 mm thickness (88%) and the lowest was determined for feldspathic ceramic with 1 mm thickness (44%). The differences among the different ceramics and between the different thicknesses were significant (pCeramic type and thickness should be taken into consideration to adjust the laser irradiation parameters during laser debonding of adhesively luted all-ceramic restorations.

  10. Neodymium YAG lasers pumped by light-emitting diodes

    Bilak, V.I.; Goldobin, I.S.; Zverev, G.M.; Kuratev, I.I.; Pashkov, V.A.; Stel' makh, M.F.; Tsvetkov, Y.V.; Solov' eva, N.M.


    The results are presented of theoretical and experimental investigations of room-temperature YAG:Nd lasers pumped by light-emitting diodes. The lasing characteristics of a laser operated at the 1.06 and 1.32 wavelengths were investigated in the cw and pulsed regimes and dependences of its parameters on the temperature, pulse repetition frequency, and other factors were studied. In the pulsed regime the laser efficiency was 0.2% and in the cw regime the radiation power reached 50 and 17 mW at the 1.06 and 1.32 wavelengths, respectively.

  11. Temperature variation during apicectomy with Er:YAG laser.

    Bodrumlu, Emre; Keskiner, Ilker; Sumer, Mahmut; Sumer, A Pinar; Telcıoglu, N Tuba


    The purpose of this in vitro study was to evaluate the generated temperature of the Er:YAG laser, with three different pulse durations for apicectomy, compared with tungsten bur and surgical saw. Apicectomy is an endodontic surgery performed to remove the root apex and curette adjacent periapical tissue because of lesions of the apical area that are not healing properly. Sixty single-rooted extracted human teeth were resected by three cutting methods: tungsten bur, surgical saw, and Er:YAG laser irradiation with three different pulse durations; pulse duration 50 μs, pulse duration 100 μs, and pulse duration 300 μs. Teflon-insulated, type K thermocouples were used to measure temperature changes during the apicectomy process. Data were analyzed using the general linear models procedure of the SPSS statistical software program. Although there was no statistically significant difference for the mean values of temperature changes at 1 mm away to the cutting site of teeth, there was statistically significant difference among groups for the mean values of temperature changes at 3 mm away to the cutting site of teeth. Additionally, there was statistically significant difference among groups for the total time required for apicectomy. The laser irradiation with pulse duration 50 μs appears to have the lowest temperature rise and the shortest time required for apicectomy of the three pulse durations. However, Er:YAG laser for apicectomy in all pulse durations could be used safely for resection in endodontics in the presence of sufficient water.

  12. Holmium:YAG laser in dentistry: photoconditioning of dentinal surfaces

    Holt, Raleigh A.; Nordquist, Robert E.


    This in vitro study was undertaken to determine energy levels necessary to produce tubule closure and surface smoothing on dentinal surfaces of human teeth and their resultant temperature increases within the pulpal canals with the Holmium:YAG laser. An optimal working spot size and even absorption pattern were produced by defocusing the laser beam and evaluated by images produced on light exposed and developed photographic paper. The surface effects on dentin were examined by scanning electron microscopy. A thermocouple was positioned in the canals of fresh dissected dog jaws and attached to a recorder which produced a graph of the temperature changes. The in vitro research model for intrapulpal temperatures changes was verified by comparing premortem and postmortem temperature readings. The same protocol was used to evaluate temperature changes in fresh human extracted teeth. In vivo histological studies were conducted to evaluate the effects of HO:YAG laser energy on pulpal tissues. The results of these studies indicate the HO:YAG laser at a wavelength of 2.12 microns can be safely and effectively used for photoconditioning of the dentinal surfaces of teeth in clinical conditions.

  13. Intracorporeal lithotripsy with the holmium:YAG laser

    Denstedt, John D.; Razvi, Hassan A.; Chun, Samuel S.; Sales, Jack L.


    A variety of devices are currently available for intracorporeal stone fragmentation. Recently a new wavelength of laser, the Holmium:YAG, has demonstrated a variety of potential urologic applications including ablation of soft tissue lesions as well as stone fragmentation. This laser has a wavelength of 2100 nm and operates in a pulsed mode. Energy is delivered through a 400 um quartz end-firing fiber. In this presentation we review our clinical experience with the Holmium:YAG laser for the treatment of renal and ureteral calculi. Over a 23 month period, 63 patients underwent 67 procedures. Seven procedures consisted of percutaneous nephrolithotripsy for large or staghorn renal calculi. Sixty procedures were performed for ureteral stones. Procedures for proximal ureteral stones (6) employed a retrograde approach using flexible ureteroscopes (8.5 or 9.8). Stones in the mid ureter (12) and distal ureter (42) were approached transurethrally using a 6.9 rigid ureteroscope. Complete stone fragmentation without the need for additional procedures was achieved in 82% of cases. Treatment failures included 1 stone migration into the renal pelvis during laser activation, 6 patients who had incomplete fragmentation and 3 patients in which laser malfunction precluded complete fragmentation. Stone analysis available in 23 patients revealed calcium oxalate monohydrate (15), calcium oxalate dihydrate (2), cystine (2), uric acid (3) and calcium phosphate (1). A single complication of ureteral perforation occurred when the laser was fired without direct visual guidance. Radiographic follow-up at an average of 16 weeks is available in 22 patients and has identified 2 patients with ureteral strictures that are not believed to be related to laser lithotripsy. In summary, we have found the Holmium:YAG laser to be a reliable and versatile device for intracorporeal lithotripsy. Its safety and efficacy make it a suitable alternative for performing intracorporeal lithotripsy of urinary

  14. Vitreous humor rheology after Nd:YAG laser photo disruption.

    Abdelkawi, Salwa A; Abdel-Salam, Ahmed M; Ghoniem, Dina F; Ghaly, Sally K


    This work aimed to consider the hazardous side effect of eye floaters treatment with Q-switched Nd:YAG laser on the protein and viscoelastic properties of the vitreous humor, and evaluate the protective role of vitamin C against laser photo disruption. Five groups of New Zealand rabbits were divided as follows: control group for (n = 3) without any treatment, the second group (n = 9) treated with Q-switched Nd:YAG laser energy of 5 mJ × 100 pulse delivered to the anterior, middle, and posterior vitreous, respectively (n = 3 for each). The third group (n = 9) received a daily dose of 25 mg/kg body weight vitamin C for 2 weeks, and then treated with laser as the previous group. The fourth group (n = 9) treated with 10 mJ 9 50 pulse delivered to the anterior, middle, and posterior vitreous, respectively (n = 3 rabbits each). The fifth group (n = 9) received a daily dose of 25 mg/kg body weight vitamin C for 2 weeks, and then treated with laser as the previous group. After 2 weeks of laser treatment, the protein content, refractive index (RI), and the rheological properties of vitreous humor, such as consistency, shear stress, and viscosity, were determined. The results showed that, the anterior vitreous group exposed to of 5 mJ × 100 pulse and/or supplemented with vitamin C, showed no obvious change. Furthermore, all other treated groups especially for mid-vitreous and posterior vitreous humor showed increase in the protein content, RI and the viscosity of vitreous humor. The flow index remained below unity indicating the non-Newtonian behavior of the vitreous humor. Application of Q-switched Nd:YAG laser should be restricted to the anterior vitreous humor to prevent the deleterious effect of laser on the gel state of the vitreous humor.

  15. Argon laser versus erbium:YAG laser in the treatment of xanthelasma palpebrarum

    Abdelkader, Mona; Alashry, Shereen Ezzelregal


    Background Xanthelasma palpebrarum is the most common of the xanthomas with asymptomatic, symmetrical, bilateral, soft, yellow, polygonal papules around the eyelids. Though it is a benign lesion causing no functional disturbance, it is esthetically annoying. The surgical laser offers an extremely elegant and powerful solution to this problem. Objective To evaluate the effectiveness of erbium:YAG and argon lasers in the treatment of xanthelasma lesions. Patients and methods Forty patients were included in the study. Twenty patients (15 patients were bilateral with 30 eyes either in the upper or lower lid and 5 patients were unilateral) were treated with erbium:YAG laser. Another 20 patients (10 patients were bilateral with 20 eyes and 10 patients were unilateral) were treated with argon laser. Results In the majority of treated patients (either treated with erbium:YAG or argon laser), xanthelasma lesions were completely disappeared or significantly decreased in size. Two patients showed pigmentary changes in the form of hypopigmentation with erbium:YAG laser (one case), another case showed hyperpigmentation. No intraoperative complication was observed. No significant scar or recurrence was observed. Conclusion Argon laser in xanthelasma is an easy, effective, and safe method of treatment for small lesions and YAG laser is more better for large lesions than argon laser. PMID:25892929

  16. Hollow polycarbonate fiber for Er:YAG laser light delivery.

    Nakazawa, Masayuki; Shi, Yi-Wei; Matsuura, Yuji; Iwai, Katsumasa; Miyagi, Mitsunobu


    We developed hollow fibers with polycarbonate (PC) capillaries for use as a supporting tube. The PC capillaries were prepared by using a glass-drawing technique. Hollow PC fibers are safer and more flexible than hollow glass fibers because no fragments are released when the fibers are broken in various applications. Inner coating layers of silver and cyclic olefin polymer (COP) enhanced the reflection rate at the Er:YAG laser light wavelength. Using these fibers, we attained low loss for Er:YAG laser light transmission. By adjusting the drawing temperature in the fabrication of the PC capillaries, we created a smooth inner surface and uniform PC capillaries. We also demonstrated low-loss properties for visible pilot beams.

  17. Holmium:YAG laser angioplasty: treatment of acute myocardial infarction

    Topaz, On


    We report our clinical experience with a group of 14 patients who presented with acute myocardial infarction. A holmium:YAG laser was applied to the infarct-related artery. This laser emits 250 - 600 mJ per pulse, with a pulse length of 250 microseconds and repetition rate of 5 Hz. Potential benefits of acute thrombolysis by lasers include the absence of systemic lytic state; a shortened thrombus clearing time relative to using thrombolytics; safe removal of the intracoronary thrombus and facilitation of adjunct balloon angioplasty. Potential clinical difficulties include targeting the obstructive clot and plaque, creation of debris and distal emboli and laser-tissue damage. It is conceivable that holmium:YAG laser can be a successful thrombolytic device as its wave length (2.1 microns) coincides with strong water absorption peaks. Since it is common to find an atherosclerotic plaque located under or distal to the thrombotic occlusion, this laser can also be applied for plaque ablation, and the patient presenting with acute myocardial infarction can clearly benefit from the combined function of this laser system.

  18. Er:YAG crystal temperature influence on laser output characteristics

    Němec, Michal; Å ulc, Jan; Hubka, Zbyněk.; Hlinomaz, Kryštof; Jelínková, Helena


    The main goal of this work was to investigate the influence of the temperature of the Er:YAG active medium on laser properties in eye-safe spectral region for three various pump wavelengths. The tested Er:YAG sample doped by 0.5% of Er3+ ions had a cylindrical shape with 25mm in length and 5mm in diameter. The absorption spectrum of the Er:YAG active medium in the range from 1400nm up to 1700nm for temperatures 80K and 300K was measured. The crystal was placed inside the vacuum chamber of a liquid nitrogen cooled cryostat. The temperature was controlled within the 80 - 340K temperature range. Three pump sources generating at 1535, 1452, and 1467nm were applied. The first one was flash lamp pumped Er:glass laser (repetition rate 0.5 Hz, pulse duration 1 ms, pulse energy 148 mJ). The further two sources were fiber coupled laser diodes (repetition rate 10 Hz, pulse duration 10 ms, maximum pulse energies 106mJ and 195 mJ). The semi-hemispherical laser resonator consisted of a pump curved mirror and output plan coupler with a reflectivity of 90% @ 1645 nm. The laser output characteristics were investigated in dependence on temperature of active medium for three laser pumping systems. The output energy has an optimum in dependence on active medium temperature and pump wavelengths. The maximal generated laser energies were 16.2mJ (90 K), 28.7mJ (120 K), and 33.2mJ (220 K), for pump wavelengths 1452 nm, 1467 nm, and 1535 nm, respectively.

  19. Continuous-wave yellow laser generation at 578 nm by intracavity sum-frequency mixing of thin disk Yb:YAG laser and Nd:YAG laser

    Ma, Gangfei; Yang, Jianming; Tan, Huiming; Tian, Yubing; Yao, Wenming; Ju, Qiaojun; Zhang, Long; Chen, Jiansheng; Wu, Xiaodong; Gao, Jing


    We report a continuous-wave yellow laser at 578 nm obtained by doubly resonant intracavity sum-frequency mixing of thin disk Yb:YAG laser and Nd:YAG laser with a LBO nonlinear crystal. Single-wavelength laser operation at 578 nm by using a silica etalon as a wavelength selector and dual-wavelength operation at 578 nm and 582 nm are obtained with maximum output powers of 100 mW and 136 mW, respectively. The single wavelength operating power stability value in 30 min was 4.7%, which was improved ∼21.6%, compared with that of dual-wavelength operation.

  20. LIGHT SOURCE: TW Laser system for Thomson scattering X-ray light source at Tsinghua University

    Yan, Li-Xm; Du, Ying-Chao; Du, Qiang; Li, Ren-Kai; Hua, Jian-Fei; Huang, Wen-Hui; Tang, Chuan-Xiang


    A TW (Tera Watt) laser system based on Ti:sapphire mainly for the Tsinghua Thomson scattering X-ray light source (TTX) is being built. Both UV (ultraviolet) laser pulse for driving the photocathode radio-frequency (RF) gun and the IR (infrared) laser pulse as the electron-beam-scattered-light are provided by the system. Efforts have also been made in laser pulse shaping and laser beam transport to optimize the high-brightness electron beam production by the photocathode RF gun.

  1. TW Laser system for Thomson scattering X-ray light source at Tsinghua University

    YAN Li-Xin; DU Ying-Chao; DU Qiang; LI Ren-Kai; HUA Jian-Fei; HUANG Wen-Hui; TANG Chuan-Xiang


    A TW(Tera Watt)laser system based on Ti:sapphire mainly for the Tsinghua Thomson scattering X-ray light source(TTX)is being built.Both UV(ultraviolet)laser pulse for driving the photocathode radiofrequency(RF)gun and the IR(infrared)laser pulse as the electron-beam-scattered-light are provided by the system.Efforts have also been made in laser pulse shaping and laser beam transport to optimize the high-brightness electron beam production by the photocathode RF gun.

  2. High Average Power Yb:YAG Laser

    Zapata, L E; Beach, R J; Payne, S A


    We are working on a composite thin-disk laser design that can be scaled as a source of high brightness laser power for tactical engagement and other high average power applications. The key component is a diffusion-bonded composite comprising a thin gain-medium and thicker cladding that is strikingly robust and resolves prior difficulties with high average power pumping/cooling and the rejection of amplified spontaneous emission (ASE). In contrast to high power rods or slabs, the one-dimensional nature of the cooling geometry and the edge-pump geometry scale gracefully to very high average power. The crucial design ideas have been verified experimentally. Progress this last year included: extraction with high beam quality using a telescopic resonator, a heterogeneous thin film coating prescription that meets the unusual requirements demanded by this laser architecture, thermal management with our first generation cooler. Progress was also made in design of a second-generation laser.

  3. Dual-polarization mode-locked Nd:YAG laser.

    Thévenin, J; Vallet, M; Brunel, M


    A mode-locked solid-state laser containing a birefringent element is shown to emit synchronously two frequency combs associated to the two polarization eigenstates of the cavity. An analytical model predicts the polarization evolution of the pulse train, which is determined by the adjustable intracavity birefringence. Experiments realized with a Nd:YAG laser passively mode locked by a semiconductor saturable absorber mirror are in perfect agreement with the model. Locking between the two combs arises for particular values of their frequency difference, e.g., half the repetition rate, and the pulse train polarization sequence is then governed by the relative overall phase offset of the two combs.

  4. Amalgam Surface Treatment by Different Output Powers of Er:YAG Laser:SEM Evaluation.

    Hosseini, Mohammad Hashem; Hassanpour, Mehdi; Etemadi, Ardavan; Ranjbar Omrani, Ladan; Darvishpour, Hojat; Chiniforush, Nasim


    The purpose of this study was to evaluate amalgam surfaces treated by different output powers of erbium-doped yttrium aluminum garnet (Er:YAG) laser by scanning electron microscope (SEM). Twenty-one amalgam blocks (8 mm × 8 mm, 3 mm thickness) were prepared by condensing silver amalgam (into putty impression material. After keeping them for 24 hours in distilled water, they were divided into 7 groups as follow: G1: Er:YAG laser (1 W, 50 mJ), G2: Er:YAG laser (2 W, 100 mJ), G3: Er:YAG laser (3 W, 150 mJ), G4: Sandblast, G5: Sandblast + Er:YAG laser (1 W, 50 mJ), G6: Sandblast +Er:YAG laser (2 W, 100 mJ) and G7: Sandblast +Er:YAG laser (3 W, 150 mJ). Then after preparation of all samples, they were examined by SEM. The SEM results of amalgam surfaces treated by different output powers of Er:YAG laser showed some pitting areas with non-homogenous irregularities Conclusion: It seems that the application of sandblasting accompanied by Er:YAG laser irradiation can provide proper surface for bonding of orthodontic brackets.

  5. Histological and TEM examination of early stages of bone healing after Er:YAG laser irradiation.

    Pourzarandian, Amir; Watanabe, Hisashi; Aoki, Akira; Ichinose, Shizuko; Sasaki, Katia M; Nitta, Hiroshi; Ishikawa, Isao


    The aim of this study was to analyze the early healing process of bone tissue irradiated by Er:YAG laser and compare it with that treated by mechanical drilling and CO(2) laser. Er:YAG laser has a great potential for cutting hard tissues as it is capable of ablation with less thermal damage. Twenty-four male Wistar rats were used for this study. The calvarial bone of rats was exposed and straight grooves were prepared by Er:YAG laser, mechanical bur and continuous wave CO(2) laser. Four rats each were sacrificed at six time points: 10 min, 6 and 24 h and 3, 7, and 14 days post-surgery. Sections were prepared for light and transmission electron microscopic (TEM) observations. Compared to mechanical bur and CO(2) groups, the inflammatory cell infiltration adjacent to the irradiated bone surface, fibroblastic reaction, and revascularization were more pronounced in the Er:YAG laser-irradiated tissues. A cell-rich granulation tissue with fibroblasts and osteoblasts was predominant in 7-day specimens of Er:YAG laser group. Histopathological analysis of 14-day specimens in the Er:YAG group also revealed significantly greater new bone formation, compared with the mechanical bur and CO(2) laser groups. Initial bone healing following Er:YAG laser irradiation occurred faster than that after mechanical bur and CO(2) laser. Er:YAG laser treatment may be advantageous for wound healing of bone tissue, presumably by providing a favorable surface for cell attachment.

  6. Stability of a Laser-diode-pumped Cr4+∶YAG Passively Q-switched Nd3+∶YAG Laser

    ZHANG Xingyu; ZHAO Shengzhi; WANG Qingpu; ZHANG Qidi; B. Ozygus; M. Weber


    In this paper, the stability of a laser-diode-pumped Cr4+∶YAG passively Nd3+∶YAG Q-switched laser and the influence of the transversal mode structure on the stability are investigated. With the laser operating in TEM00 mode, the pulse energy fluctuation and the repetition rate fluctuation as functions of the repetition rate are measured, and semi-quantitatively and qualitatively analyzed, respectively.

  7. CO2 laser collective Thomson scattering diagnostics on the HT-7 tokamak

    李亚东; 李建刚; 毛剑珊


    A CW CO2 laser collective Thomson scattering diagnostics was developed to measure plasma density fluctuations on the HT-7 tokamak. The design and construction of CO2 laser scattering apparatus is described. The laser source is a continuous-wave CO2 laser with a cavity length of 1.9 m and a power output of about 10 W at 10.6 μm. The k-resolution of the system is △k ≈ 3.2 cm-1. The preliminary data from the diagnostic is presented.

  8. LED pumped Nd:YAG laser development program

    Farmer, G. I.; Kiang, Y. C.; Lynch, R. J.


    The results of a development program for light emitting diode (LED) pumped Nd:YAG lasers are described. An index matching method to increase the coupling efficiency of the laser is described. A solid glass half-cylinder of 5.0 by 5.6 centimeters was used for index matching and also as a pumping cavity reflector. The laser rods were 1.5 by 56 millimeters with dielectric coatings on both end surfaces. The interfaces between the diode array, glass cylinder, and laser rod were filled with viscous fluid of refractive index n = 1.55. Experiments performed with both the glass cylinder and a gold coated stainless steel reflector of the same dimensions under the same operating conditions indicate that the index matching cylinder gave 159 to 200 percent improvement of coupling efficiency over the metal reflector at various operating temperatures.

  9. Er:YAG and Nd:YAG laser in treatment of patients with contraindications of conventional dental and maxillofacial surgery

    Smucler, Roman; Mazanek, Jiri


    In clinical praxis we must treat patients with some relative or absolute contraindications every day. Need of hospitalization, antibiotics, hemostyptics and complex examinations makes dentoalveolar and maxillofacial surgery in those cases quite expensive. Combination of Nd:YAG and Er:YAG laser gives us new possibilities. We can help some untreatable patients or transfer care from hospital to dental office. We have been trying to solve contraindications for laser therapy five years. In the center of our work are disorders of blood coagulation, immunity and metabolism. Nd:YAG laser is very useful in coagulation and vaporization of dental gum hypertrophies, benign and malign tumors in case of chronic anticoagulation therapy and immunosupress / in combination for example- after heart transplantation /. Special chapter is the care of patients with disseminated tumors. Er:YAG laser large solve big lesions because of minimal invasivity of course but for small benign tumors are recidives is ideal. Better and quicker healing make new standard of patients' cooperation. Generally fashionable and more comfortable laser treatment minimize need of general anesthesia. After five years we use complex laser therapy in our routine. Aim of our new work is to find ideal combination of cutting lasers to minimize classical complications of laser surgery / carbonization, long and secondary healing /.

  10. Investigation of bulk laser damage in transparent YAG ceramics controlled with microstructural refinement

    Kamimura, T.; Kawaguchi, Y.; Arii, T.; Shirai, W.; Mikami, T.; Okamoto, T.; Aung, Yan Lin; Ikesue, A.


    We have investigated a relationship among the bulk laser-induced damage threshold (LIDT) and YAG ceramics with various structural defects. The correlation of scattering defect density and laser damage resistance was clearly observed. A high-quality YAG ceramic having a low-scattering density showed a higher LIDT than that of a low-quality YAG ceramic. Laser damage threshold (LIDT) of high-quality YAG ceramic was almost the same as that of a single crystal. In addition, the high-quality Nd:YAG ceramics with low-defect density showed an excellent oscillation efficiency which was comparable to that of a single crystal. Thus, high-quality YAG ceramic with low-defect density is more reliable as a material which is highly resistant to laser damage.

  11. A multiple work mode YAG laser in derma surgery

    Sa, Yu; Zhang, Guizhong; Ye, Zhisheng; Yu, Lin


    It has been very common that a pulse laser is used in derma surgery based on the theory of "Selective Photothermolysis". This method has also been accepted as the best way to treat the pigments by the medical textbook. A kind of double-pulsed laser which gets the name by two pulse output at one pumping process is developed for derma surgery lately, and this kind of laser has been proved more effective and safe than single-pulse laser. We also develop a multiple work mode YAG laser including two double-pulsed modes at 1064nm and 532nm, two single-pulsed modes at 1064nm and 532nm, and one free-running mode at 1064nm. Considering availability, security and reliability of the laser as a surgery machine, some important subsystems of the laser are optimized carefully, such as Q-switch driver, wavelength-switching system, power supply, and control system etc. At last we get a prototype laser which can run for longer than 30 minutes continuously, and output Max10 pulse per second (pps) with Max800mJ energy at 1064nm double Q-Switch mode, or Max400mJ at 532nm. Using double pulse mode of the laser we do some removal experiments of tattoos and other pigments, and obtain good effect.

  12. Treatment of rosacea with long-pulsed Nd: YAG laser

    Ekin Meşe Say


    Full Text Available Background and Design: Rosacea is a chronic inflammatory disorder of the face. There is no curative treatment for the disease. Facial flushing and vascular lesions due to rosacea may significantly affect a patient’s quality of life. Topical and oral antibiotics are not effective for treating rosacea. Currently, laser treatment of vascular lesions has been reported in the literature. We aimed to investigate the efficacy of long-pulse 1064-nm neodymium: YAG (Nd: YAG laser in the treatment of vascular lesions (erythema and telangiectasia in rosacea patients. Materials and Methods: Thirty-nine patients (29 women, 10 men with erythematotelangiectatic rosacea (ETR were recruited into the study. Severity of the disease (ETR-score: 0-3 was assessed for all patients. We used long-pulsed Nd: YAG laser for vascular lesions at 3-4 weeks intervals. The face was divided into seven anatomic regions for evaluation. Assessment was made by comparing pretreatment and posttreatment photographs by using ETR-scores. For evaluating patient satisfaction, a scale of 0 to 3 was used. Results: The patients were divided into three groups according to the ETR scores [ETR-1 (n=12, ETR-2 (n=9, ETR-3 (n=18]. Following an average of 3.95 (2-8 sessions laser treatments, the clinical improvement was statistically significant in all groups (p<0.05. The mean reduction of ETR-score was 91.70% in patients with ETR-1 and. the clinical improvement was to be decreased in severe forms of ETR. The most common sites for the lesions were the malar region, ala nasi and the nasal dorsum, respectively. The lesions on the ala nasi were more recalcitrant to the treatment than those on the other areas. Regarding to physician assessment of treatment’s success, 97% of the patients was associated with moderate and excellent improvement. According to physicians’ assessment, excellent improvement was noticed in 43.58% and, 61.5% of patients reported a high degree of satisfaction with this

  13. Numerical simulation of a battlefield Nd:YAG laser

    Henriksson, Markus; Sjoqvist, Lars; Uhrwing, Thomas


    A numeric model has been developed to identify the critical components and parameters in improving the output beam quality of a flashlamp pumped Q-switched Nd:YAG laser with a folded Porro-prism resonator and polarization output coupling. The heating of the laser material and accompanying thermo-optical effects are calculated using the finite element partial differential equations package FEMLAB allowing arbitrary geometries and time distributions. The laser gain and the cavity are modeled with the physical optics simulation code GLAD including effects such as gain profile, thermal lensing and stress-induced birefringence, the Pockels cell rise-time and component aberrations. The model is intended to optimize the pumping process of an OPO providing radiation to be used for ranging, imaging or optical countermeasures.

  14. Q-switched Nd:YAG optical vortex lasers.

    Kim, D J; Kim, J W; Clarkson, W A


    Q-switched operation of a high-quality Nd:YAG optical vortex laser with the first order Laguerre-Gaussian mode and well-determined helical wavefronts using a fiber-based pump beam conditioning scheme is reported. A simple two-mirror resonator incorporating an acousto-optic Q-switch was employed, along with an etalon and a Brewster plate to enforce the particular helicity of the output. The laser yielded Q-switched pulses with ~250 μJ pulse energy and ~33 ns pulse duration (FWHM) at a 0.1 kHz repetition rate for 5.1 W of absorbed pump power. The handedness of the helical wavefronts was preserved regardless of the repetition rates. The prospects of further power scaling and improved laser performance are discussed.

  15. Er:YAG laser for endodontics: efficiency and safety

    Hibst, Raimund; Stock, Karl; Gall, Robert; Keller, Ulrich


    Recently it has been shown that bacterias can be sterilized by Er:YAG laser irradiation. By optical fiber transmission the bactericidal effect can also be used in endodontics. In order to explore potential laser parameters, we further investigated sterilization of caries and measured temperatures in models simulating endodontic treatment. It was found out that the bactericidal effect is cumulative, with single pulses being active. This offers to choose all laser parameters except pulse energy (radiant exposure) from technical, practical or safety considerations. For clinical studies the following parameter set is proposed for efficient and safe application (teeth with a root wall thickness > 1 mm, and prepared up to ISO 50): pulse energy: 50 mJ, repetition rate: 15 Hz, fiber withdrawal velocity: 2 mm/s. With these settings 4 passes must be performed to accumulate the total dose for sterilization.

  16. Use of the holmium:YAG laser in urology

    Mattioli, Stefano


    The Holmium-YAG is a versatile laser with multiple soft- tissue applications including tissue incision and vaporization, and pulsed-laser applications such as lithotripsy. At 2140 nanometers, the wavelength is highly absorbed by tissue water. Further, like CO2 laser, the Holmium produces immediate tissue vaporization while minimizing deep thermal damage to surrounding tissues. It is an excellent instrument for endopyelotomy, internal urethrotomy, bladder neck incisions and it can be used to resect the prostate. The Holmium creates an acute TUR defect which gives immediate results like the TURP. More than 50 patients were treated from Jan. 1996 to Jan. 1997 for obstructive symptoms due to benign prostatic hyperplasia, bladder neck stricture, urethral stenosis, and superficial bladder tumors.

  17. Passive mode locking of a Nd:YAG laser with co-doped Nd, Cr:YAG as saturable absorber

    Yang Lin(杨林); Feng Bao-Hua(冯宝华); Zhang Zhi-Guo(张治国); Gaebler Volker; Liu Bai-Ning(刘百宁); Eichler Hans


    We demonstrate the characteristics of relatively low saturation intensity using co-doped Nd, Cr:YAG as saturable absorber for passively mode locking the Nd:YAG laser. The difference of the saturation intensity between Q-switched and mode-locked operation in co-doped Nd, Cr:YAG was only one to two orders of magnitude, while Cr:YAG was generally reported at a difference of five orders of magnitude. More than 80% mode locking modulation depth was achieved at an incident pump power of 4.4W, corresponding to an intracavity intensity of 6 × 104W/cma2, using a 68cm long plano-concave cavity.

  18. Evaluation in vitro of effects of Er:YAG and Nd:YAG lasers irradiation on root canal wall, by stereoscopy, scanning electron micrography and thermographic camera; Avaliacao in vitro dos efeitos da irradiacao laser de Er:YAG e Nd:YAG na parede dentinaria do canal radicular, sob observacao do estereoscopio, da micrografia eletronica e da camera termografica

    Goya, Claudia


    This study was carried out to evaluate in vitro the effects of Nd:YAG laser and Er:YAG laser irradiation in the root canal wall by SEM, evaluating the apical leakage and the temperature changes during the laser irradiation. Seventy four extracted human teeth were used, they were instrumented and divided into seven groups of 10 teeth each. The teeth were evaluated through stereoscopy, by SEM, and with the thermographic camera. The Nd:YAG laser irradiation parameters were 100 mJ/p, 15 Hz, and Er:YAG laser were 160 mJ/p and 10 Hz, the irradiation was 4 times at 2 mm/sec speed, with 20 sec interval. The apical leakage was not observed in the teeth irradiated by Nd:YAG laser alone or in association with Er:YAG laser. However in the teeth irradiated only by the Er:YAG laser we observed a little leakage. By SEM observation the Nd:YAG laser irradiation showed melting and recrystallization in the dentin surface closing dentinal tubules, and in the samples irradiated by Er:Y AG laser a clean surface, opened dentinal tubules, and the combination by two lasers, showed melting covering some dentinal tubules The thermographic study found the temperature increase was not more than 6 deg C. This study showed the safety parameters applications of Er:YAG laser in association with Nd:YAG laser in root canal treatment, in order to not cause thermal damages to the periodontal tissues. (author)

  19. Neodymium YAG laser for treatment of oral cavernous hemangiomas

    Bradley, Paul F.


    Oral cavernous haemangiomas are common lesions which may require treatment due to episodes of bleeding when bitten or deformity particularly when involving the lips and/or cheeks. Surgery can be hazardous due to haemorrhage while cryosurgery tends to be tedious for large lesions and be accompanied by major oedema. Sclerosants produce hard bulky masses. Embolization is seldom helpful due to lack of arterial feeders. The Nd:YAG laser is proving a useful modality in the oro-facial region and appeared worth investigating for these lesions in a laboratory animal model, by thermography and in the clinical situation.

  20. FT-Raman spectroscopic characterization of enamel surfaces irradiated with Nd:YAG and Er:YAG lasers

    Shahabi, Sima; Fekrazad, Reza; Johari, Maryam; Chiniforoush, Nasim; Rezaei, Yashar


    Background. Despite recent advances in dental caries prevention, caries is common and remains a serious health problem. Laser irradiation is one of the most common methods in preventive measures in recent years. Raman spectroscopy technique is utilized to study the microcrystalline structure of dental enamel. In this study, FT-Raman spectroscopy was used to evaluate chemical changes in enamel structure irradiated with Nd:YAG and Er:YAG lasers. Methods. We used 15 freshly-extracted, non-carious, human molars that were treated as follows: No treatment was carried out in group A (control group); Group B was irradiated with Er:YAG laser for 10 seconds under air and water spray; and Group C was irradiated with Nd:YAG laser for 10 seconds under air and water spray. After treatment, the samples were analyzed by FT-Raman spectroscopy. Results. The carbonate content evaluation with regard to the integrated area under the curve (1065/960 cm–1) exhibited a significant reduction in its ratio in groups B and C. The organic content (2935/960 cm-1) area exhibited a significant decrease after laser irradiation in group B and C. Conclusion. The results showed that the mineral and organic matrices of enamel structure were affected by laser irradiation; therefore, it might be a suitable method for caries prevention. PMID:28096945

  1. FT-Raman spectroscopic characterization of enamel surfaces irradiated with Nd:YAG and Er:YAG lasers

    Sima Shahabi


    Full Text Available Background. Despite recent advances in dental caries prevention, caries is common and remains a serious health problem. Laser irradiation is one of the most common methods in preventive measures in recent years. Raman spectroscopy technique is utilized to study the microcrystalline structure of dental enamel. In this study, FT-Raman spectroscopy was used to evaluate chemical changes in enamel structure irradiated with Nd:YAG and Er:YAG lasers. Methods. We used 15 freshly-extracted, non-carious, human molars that were treated as follows: No treatment was carried out in group A (control group; Group B was irradiated with Er:YAG laser for 10 seconds under air and water spray; and Group C was irradiated with Nd:YAG laser for 10 seconds under air and water spray. After treatment, the samples were analyzed by FT-Raman spectroscopy. Results. The carbonate content evaluation with regard to the integrated area under the curve (1065/960 cm–1 exhibited a significant reduction in its ratio in groups B and C. The organic content (2935/960 cm-1 area exhibited a significant decrease after laser irradiation in group B and C. Conclusion. The results showed that the mineral and organic matrices of enamel structure were affected by laser irradiation; therefore, it might be a suitable method for caries prevention.

  2. 1.8kW laser diode pumped YAG laser; Shutsuryoku 1.8kW no handotai laser reiki YAG laser



    Toshiba Corporation, as a participant in Ministry of International Trade and Industry`s `photon measurement and processing technology project` since August, 1997, is engaged in the development of an energy-efficient LD (laser diode) pumped semiconductor YAG (yttrium-aluminum-garnet) laser device to be used for welding and cutting. It is a 5-year project and the goal is a mean output of 10kW and efficiency of 20%. In this article, a simulation program is developed which carries out calculation about element technology items such as the tracking of the beam from the pumping LD and the excitation distribution, temperature distribution, thermal stress distribution, etc., in the YAG rod. An oscillator is constructed, based on the results of the simulation, and it exhibits a world-high class continuous laser performance of a 1.8kW output and 13% efficiency. The record of 13% efficiency is five times higher than that achieved by the conventional lamp-driven YAG laser device. (translated by NEDO)

  3. Dacriocistorrinostomia transnasal vídeo-endoscópica com Nd: YAG laser e diodo laser Endonasal dacriocystorhinosthomy with Nd: YAG laser and diodo laser

    Eurípedes da Mota Moura


    Full Text Available OBJETIVO: Avaliar a técnica de dacriocistorrinostomia para o tratamento das obstruções do ducto lacrimo-nasal, pela vídeo-endoscopia transnasal com ND:YAG "laser" e Diodo "laser". MÉTODOS: Cinqüenta e uma cirurgias de dacriocistorrinostomia transnasal vídeo-endoscópica com Nd:YAG "laser" e Diodo "laser" foram realizadas em 42 pacientes, 36 do sexo feminino e 6 do masculino com idade variando de 3 a 92 anos; idade média 52,3 anos, no período de abril 1997 a fevereiro 2003. RESULTADO: O índice de sucesso na remissão dos sintomas foi de 92,15%. Em todos os pacientes era feita entubação bicanalicular com silicone e mantida por seis a oito semanas. CONCLUSÕES: A técnica empregada mostrou-se eficaz no tratamento das obstruções do ducto lacrimo-nasal. Não se observou diferença de resultados quando se utilizou Nd:YAG e Diodo "laser". O pós-operatório em todos os casos foi confortável e sem hemorragias.PURPOSE: To evaluate the technique of dacryocysthorrinosthomy for the treatment of nasolacrimal duct obstruction, by transnasal endoscopic video-assisted approach with Nd:YAG laser and diode laser. METHODS: Fifty one surgeries dacryocysthorrinostomy transnasal endoscopic video assisted were performed in 42 patients, 36 females, 6 males, aged between 3 and 92 years, mean age 52.3 years, in the period of April 1997 to February 2003. RESULT: The surgery successfully relieved lacrimal duct obstruction in 92.15% of the patients. CONCLUSION: The technique was efficient for the treatment of nasolacrimal obstruction. In all patients bicanalicular silicone stents were inserted at the time of surgery and removed after six to eight weeks. There is no difference in the results between Nd:YAG and diode laser. The postoperative period in all cases was comfortable and there was no hemorrhage.

  4. Theoretical Analysis on the Simultaneous Operation of a Color-Center Laser and a Q-Switched Nd: YAG Laser

    WU Xing; DING Yongkui; ZHANG Rui


    The simultaneous operation for the Q- switched Nd: YAG laser at 1.06 and the tunable color-center laser over 1.12~1.26 μm has been realized by using a LiF: F2- color-center crystal both as the Q-switcher for the Nd:YAG laser and as the active medium for the color-center laser. The interaction of the two lasers has been analyzed and calculated with the rate equations. The pulse duration of YAG laser is compressed, in agreement with the experimental results.

  5. Studies on Nd∶YAG Single-pass Amplifiers for High-power Q-switched Laser System

    CAO Sansong(曹三松); ZHANG Xiangyang(张向阳); HUANG Yanlin(黄燕琳); LI Guangrong(李光荣); SU Xinzhi(苏心智)


    The output of Nd∶YAG single-pass laser amplifiers is studied analytically and experimentally. Methods of analysis for single-pass Nd∶YAG laser amplifier are presented. A flashlamp-pumped Q-switched Nd∶YAG oscillator/amplifier laser system has been developed with the average output power of 121.5 W.

  6. Bonding Strength of Ceromer with Direct Laser Sintered, Ni-Cr-Based, and ZrO2 Metal Infrastructures After Er:YAG, Nd:YAG, and Ho:YAG Laser Surface Treatments-A Comparative In Vitro Study.

    Gorler, Oguzhan; Ozdemir, Ali Kemal


    Laser modalities instead of conventional surface treatment techniques have been suggested to obtain an adequate micromechanical bonding between dental super- and infrastructures. The present study was undertaken to assess the effect of surface treatment with Ho:YAG, Er:YAG, and Nd:YAG laser modalities on the shear bond strength (SBS) of ceromer to different types of metal infrastructures in in vitro settings. The study specimens consisted of 40 direct laser sintered (DLS), 40 Ni-Cr-based, and 40 zirconium oxide (ZrO2) infrastructures. In each infrastructure group, the specimens were divided randomly into five treatment modalities (n = 8): no treatment (controls), sandblasting, Er:YAG, Nd:YAG, and Ho:YAG lasers. The DLS, Ni-Cr-based, and ZrO2 infrastructures were prepared in the final dimensions of 7 mm in diameter and 3 mm in thickness in line with the ISO 11405 standard. Ceromer as superstructure was applied to all the infrastructures after their surface treatments according to the selected treatment modality. SBS test was performed to test the effectiveness of surface treatments. A stereomicroscope was used to determine the changes in the surface morphology of specimens. Among the laser modalities and sandblasting, Ho:YAG laser caused the most important increase in the DLS and Ni-Cr-based infrastructures but sandblasting caused the most important increase in the ZrO2 infrastructure. In all the infrastructures, Nd:YAG laser has the least effectiveness, and Er:YAG laser makes an intermediate success. The stereomicroscopy images presented that the applications of laser surface treatments altered the surface in all the infrastructures. Overall, in current experimental settings, Ho:YAG, Nd:YAG, and Er:YAG lasers, in order of strength, are effective in improving the bonding of ceromer to all the infrastructures. Ho:YAG laser is more effective in the DLS and Ni-Cr-based infrastructures, but sandblasting is more effective in the ZrO2 infrastructure. The studied

  7. Up Conversion Measurements in Er:YAG; Comparison with 1.6 Micrometer Laser Performance

    Barnes, Norman P.; Walsh, Brian M.; Amzajerdian, Farzin; Reichle, Donald J.; Busch, George E.; Carrion, William A.


    Up conversion significantly affects Er:YAG lasers. Measurements performed here for low Er concentration are significantly different than reported high Er concentration. The results obtained here are used to predict laser performance and are compared with experimental results.

  8. High-energy resolution Thomson Parabola spectrometer for laser plasma diagnostics

    Cirrone, G. A. P.; Schillaci, F. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania, Italy and Institute of Physics of the ASCR, ELI-Beamlines project, Na Slovance 2, Prague (Czech Republic); Carpinelli, M. [INFN Sezione di Cagliari, c/o Dipartimento di Fisica, Università di Cagliari, Cagliari (Italy); Cuttone, G.; Romano, F. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania (Italy); Maggiore, M. [Institute of Physics of the ASCR, ELI-Beamlines project, Na Slovance 2, Prague, Czech Republic and Laboratori Nazionali di Legnaro, INFN, Via Università 2, Legnaro (PD) (Italy); Ter-Avetisyan, S. [Laboratori Nazionali di Legnaro, INFN, Via Università 2, Legnaro (PD) (Italy); Tramontana, A. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania, Italy and School of Mathematics and Physics, The Queen' s University Belfast, BT7 1NN (United Kingdom); Velyhan, A. [Institute of Physics of the ASCR, ELI-Beamlines project, Na Slovance 2, Prague (Czech Republic)


    Thomson Parabola (TP) spectrometers are widely used devices for laser-driven beam diagnostics as they provide a complete set of information on the accelerated particles. A novel TP has been developed at LNS with a design able to detect protons up to 20 MeV. The layout design and some results obtained during the experimental campaign at PALS laboratory will be reported in the following.

  9. Continuous-wave and Q-switched performance of an Yb:YAG/YAG composite thin disk ceramic laser pumped with 970-nm laser diode

    Hong Cai; Jun Zhou; Hongming Zhao; Yunfeng Qi; Qihong Lou; Jingxing Dong; Yunrong Wei


    Using front face-pumped compact active mirror laser (CAMIL) structure, we have demonstrated an Yb:YAG/YAG composite ceramic disk laser with pumping wavelength at 970 nm. The laser has been operated in both continuous-wave (CW) and Q-switching modes. Under CW operation, laser output power of 1.05 W with 2% transmission output coupler was achieved at the wavelength of 1031 nm. Qswitched laser output was gotten by using an acousto-optic Q-switch. The repetition rate ranged from 1 to 30 kHz and the pulse width varied from 166 to 700 ns.

  10. Nd: YAG laser therapy of rectosigmoid bleeding due to radiation injury

    Leuchter, R.S.; Petrilli, E.S.; Dwyer, R.M.; Hacker, N.F.; Castaldo, T.W.; Lagasse, L.D.


    The Nd:YAG laser was used to treat a patient bleeding from the rectosigmoid as a result of radiation injury related to therapy for cervical carcinoma. Successful laser therapy was performed after a diverting colostomy failed to control persistent bleeding. Further surgical procedures were not required. Characteristics of Nd:YAG laser as compared with those of the carbon dioxide and argon lasers are considered.

  11. Holmium:YAG laser-assisted otolaryngologic surgery: Lahey Clinic experience

    Shapshay, Stanley M.; Rebeiz, Elie E.; Pankratov, Michail M.


    The Holmium:YAG laser was used to assist in 36 rhinologic procedures including surgery for chronic sinus disease, chronic dacryocystitis, recurrent choanal stenosis, and a sphenoid sinus mucocele. There were no laser related complications. The laser permitted controlled ablation of bone and soft tissue in all cases with satisfactory results. The Ho:YAG laser can be used in otolaryngology to assist in cases where surgical access is difficult or when controlled, precise bone and soft tissue ablation is necessary.

  12. High-average-power diode-pumped Yb: YAG lasers

    Avizonis, P V; Beach, R; Bibeau, C M; Emanuel, M A; Harris, D G; Honea, E C; Monroe, R S; Payne, S A; Skidmore, J A; Sutton, S B


    A scaleable diode end-pumping technology for high-average-power slab and rod lasers has been under development for the past several years at Lawrence Livermore National Laboratory (LLNL). This technology has particular application to high average power Yb:YAG lasers that utilize a rod configured gain element. Previously, this rod configured approach has achieved average output powers in a single 5 cm long by 2 mm diameter Yb:YAG rod of 430 W cw and 280 W q-switched. High beam quality (M{sup 2} = 2.4) q-switched operation has also been demonstrated at over 180 W of average output power. More recently, using a dual rod configuration consisting of two, 5 cm long by 2 mm diameter laser rods with birefringence compensation, we have achieved 1080 W of cw output with an M{sup 2} value of 13.5 at an optical-to-optical conversion efficiency of 27.5%. With the same dual rod laser operated in a q-switched mode, we have also demonstrated 532 W of average power with an M{sup 2} < 2.5 at 17% optical-to-optical conversion efficiency. These q-switched results were obtained at a 10 kHz repetition rate and resulted in 77 nsec pulse durations. These improved levels of operational performance have been achieved as a result of technology advancements made in several areas that will be covered in this manuscript. These enhancements to our architecture include: (1) Hollow lens ducts that enable the use of advanced cavity architectures permitting birefringence compensation and the ability to run in large aperture-filling near-diffraction-limited modes. (2) Compound laser rods with flanged-nonabsorbing-endcaps fabricated by diffusion bonding. (3) Techniques for suppressing amplified spontaneous emission (ASE) and parasitics in the polished barrel rods.

  13. High repetition rate femtosecond dye amplifier using a laser diode pumped neodymium:YAG laser

    Zysset, B.; LaGasse, M.J.; Fujimoto, J.G.; Kafka, J.D.


    A high repetition rate femtosecond dye amplifier is demonstrated using a laser diode pumped Q-switched Nd:YAG laser. Amplification of wavelength tunable 300 fs pulses from a synchronously mode-locked rhodamine dye laser is achieved with a saturated gain of 70 and a small gain of 200 at a repetition rate of 800 Hz. Maximum pulse energies of 40 nJ are obtained, and pulse compression to as short as 30 fs is demonstrated.

  14. High repetition rate femtosecond dye amplifier using a laser diode pumped neodymium:YAG laser

    Zysset, B.; LaGasse, M. J.; Fujimoto, J. G.; Kafka, J. D.


    A high repetition rate femtosecond dye amplifier is demonstrated using a laser diode pumped Q-switched Nd:YAG laser. Amplification of wavelength tunable 300 fs pulses from a synchronously mode-locked rhodamine dye laser is achieved with a saturated gain of 70 and a small gain of 200 at a repetition rate of 800 Hz. Maximum pulse energies of 40 nJ are obtained, and pulse compression to as short as 30 fs is demonstrated.

  15. Operation of the NSTX Thomson Scattering System

    LeBlanc, B.P.; Bell, R.E.; Johnson, D.W.; Hoffman, D.E.; Long, D.C.; and Palladino, R.W.


    The NSTX multi-point Thomson scattering system has been in operation for nearly two years and provides routine Te(R,t) and ne(R,t) measurements. The laser beams from two 30-Hz Nd:YAG lasers are imaged by a spherical mirror onto 36 fiber-optics bundles. In the present configuration, the output ends of 20 of these bundles are instrumented with filter polychromators and avalanche photodiode detectors. In this paper, we discuss the laser implementation and the installed collection optics. We follow with examples of raw and analyzed data. We close with some comments about calibration.

  16. Pump beam waist-dependent pulse energy generation in Nd:YAG/Cr4+:YAG passively Q-switched microchip laser

    Li, Chao-yu; Dong, Jun


    The incident pump beam waist-dependent pulse energy generation in Nd:YAG/Cr4+:YAG composite crystal passively Q-switched microchip laser has been investigated experimentally and theoretically by moving the Nd:YAG/Cr4+:YAG composite crystal along the pump beam direction. Highest pulse energy of 0.4 mJ has been generated when the Nd:YAG/Cr4+:YAG composite crystal is moved about 6 mm away from the focused pump beam waist. Laser pulses with pulse width of 1.7 ns and peak power of over 235 kW have been achieved. The theoretically calculated effective laser beam area at different positions of Nd:YAG/Cr4+:YAG composite crystal along the pump beam direction is in good agreement with the experimental results. The highest peak power can be generated by adjusting the pump beam waist incident on the Nd:YAG/Cr4+:YAG composite crystal to optimize the effective laser beam area in passively Q-switched microchip laser.

  17. Random Laser Action in Nd:YAG Crystal Powder

    Jon Azkargorta


    Full Text Available This work explores the room temperature random stimulated emission at 1.064 μm of a Nd:YAG crystal powder (Neodymium-doped yttrium aluminum garnet in a very simple pump configuration with no assistance from an internal mirror. The laser threshold energy as a function of pump beam area and pump wavelength has been measured, as well as the temporal dynamics of emission pulses. The absolute energy of stimulated emission and the absolute laser slope efficiency have been measured by using a method proposed by the authors. The results show a surprising high efficiency that takes the low Nd3+ ion concentration of the crystal powder into account.

  18. Nd:YAG Lasers Treating of Carious Lesion and Root Canal In Vitro

    Danqing Xia


    Full Text Available Dental caries is a transmissible bacterial disease process, with cavities at the end, and caused by acids from bacterial metabolism. The essence of dental treatment is to clean and disinfect bacterial contamination from the tooth. In this work, we tried to demonstrate the cleaning and disinfecting effects of Nd:YAG laser irradiation on dental carious lesion and root canal in vitro. Acousto-optic Q-switched quasicontinuous and Cr3+:YAG crystal Q-switched pulse Nd:YAG lasers were employed to treat caries lesion and the root canal, respectively. Results showed that acousto-optic Q-switched quasicontinuous Nd:YAG laser irradiation and Cr3+:YAG crystal Q-switched pulse Nd:YAG laser irradiation could rapidly clean decayed material and bacterial contamination from dental carious lesion and the narrow tail end of root canal with minimally invasive in vitro, respectively. It was concluded that acousto-optic Q-switched quasicontinuous laser irradiation may be a rapid and effective alternative caries treatment, and Cr3+:YAG crystal Q-switched pulse Nd:YAG laser irradiation may be an effective method for canal cleaning and disinfecting during root canal therapy.

  19. Noncontact Er:YAG laser ablation: clinical evaluation.

    Dostálová, T; Jelínková, H; Kucerová, H; Krejsa, O; Hamal, K; Kubelka, J; Procházka, S


    The aim of this study is to evaluate the quality of laser ablation in comparison with the classical drilling preparation. For the experiment, the Er:YAG laser drilling machine was used. The system had a laser head, water cooler, and power supply with automatic control. Spot size of 300-350 microns was used for the preparation. Repetition rate of 1-4 Hz, and pulse energies of 100-400 mJ with water spray were chosen. Cavity shape in comparison with classical drill, time of preparation, and influence of cavity shape on filling materials retention in accordance with the U.S. Public Health Service System were used. The evaluation criteria for noncontact Er:YAG ablation were done. The cavity shape is irregular, but spot surface has larger area and microretentive appearance. Caries of enamel and dentin were treated with a noncontact preparation. It was possible to remove the old insufficient fillings, except for amalgam or metal alloys. The average number of pulses was 111.22 (SE 67.57). Vibrations of microexplosions during preparation were felt by patients on 14 cavities; however, nobody felt unpleasant pain. The qualities of filling materials in laser cavities were very stable; however, cavo surface margin discoloration of 82-86% of Alfa rating could be a problem. Changes of the color and anatomic form of the tooth were observed in 4-8%. In comparison with the classical treatment, it could be said that the retention and quality of filling materials is the same or very similar.

  20. High-Efficiency High-Power Nd:YAG Laser under 885 nm Laser Diode Pumping

    LI Fang-Qin; ZHANG Xiao-Fu; ZONG Nan; YANG Jing; PENG Qin-Jun; CUI Da-Fu; XU Zu-Yan


    A high-efficiency high-power Nd:YAG laser under 885 nm laser diode (LD) pumping is demonstrated. The laser crystal is carefully designed, and the overlapping between the pump modes and the laser modes is optimized. The maximum output power at 1064 nm is 87 W under the absorbed pump power 127.7 W, corresponding to a slope efficiency of 72.4% and an optical-optical efficiency of 68.1%. The optical-optical efficiency is 58.4% for the pump power emitted directly from the LD. To our best knowledge, this is the maximal optical-optical conversion efficiency obtained for the LD end-pumped Nd:YAG lasers so far.

  1. Laser Erbium: YAG no tratamento de nevos melanocíticos Erbium: YAG laser in treatment of acquired melanocytic nevi

    Mauricio Martins


    Full Text Available FUNDAMENTOS - Os nevos melanocíticos adquiridos são observados em grande parte da população e o resultado da sua excisão, dependendo da localização, extensão e fatores inerentes ao paciente, pode ser insatisfatório. OBJETIVO - Avaliar o uso do laser Erbium: YAG no tratamento de nevos melanocíticos adquiridos MÉTODOS - Foram selecionados nove pacientes, seis homens e três mulheres, brancos, com idade entre 20 e 60 anos e desejo de remover um nevo melanocítico composto no tronco. Metade do nevo foi tratada com laser, e a outra metade foi utilizada como controle. Após um mês da aplicação, foram avaliados a cicatrização, o resultado estético e a persistência de células névicas e melanina. RESULTADOS - Houve rápida cicatrização e ótimo resultado estético, no entanto, o exame histopatológico demonstrou a permanência de células névicas e melanina em sete e em nove das amostras examinadas, respectivamente. CONCLUSÃO - A utilização do laser Erbium:YAG, com os parâmetros utilizados neste estudo, não foi capaz de destruir completamente as células névicas melanocíticas e a melanina, não sendo, portanto, recomendada para o tratamento dessas lesões, dada a possibilidade de transformação maligna futura.BACKGROUND- Acquired melanocytic nevi are commonly found and the result of their excision may not be satisfactory depending on their location, extension and factors associated to the patient. OBJECTIVE - To evaluate the use of Erbium:YAG laser in treatment of acquired melanocytic nevi. METHOD - Nine white-skinned patients were selected, six men and three women with aged 20-60 years. All desired to remove one compound acquired melanocytic nevus on the trunk. Half of the nevi was treated with Erbium YAG laser while the remaining were used as control. One month after application, healing, aesthetic results and persistence of melanocytic cells and melanin were evaluated. RESULTS - All patients presented fast healing and

  2. High resolution energy-angle correlation measurement of hard x rays from laser-Thomson backscattering.

    Jochmann, A; Irman, A; Bussmann, M; Couperus, J P; Cowan, T E; Debus, A D; Kuntzsch, M; Ledingham, K W D; Lehnert, U; Sauerbrey, R; Schlenvoigt, H P; Seipt, D; Stöhlker, Th; Thorn, D B; Trotsenko, S; Wagner, A; Schramm, U


    Thomson backscattering of intense laser pulses from relativistic electrons not only allows for the generation of bright x-ray pulses but also for the investigation of the complex particle dynamics at the interaction point. For this purpose a complete spectral characterization of a Thomson source powered by a compact linear electron accelerator is performed with unprecedented angular and energy resolution. A rigorous statistical analysis comparing experimental data to 3D simulations enables, e.g., the extraction of the angular distribution of electrons with 1.5% accuracy and, in total, provides predictive capability for the future high brightness hard x-ray source PHOENIX (photon electron collider for narrow bandwidth intense x rays) and potential gamma-ray sources.

  3. Analysis on the effect of urethra caruncle treated by Ho:YAG laser

    Zhang, Mei-Jue; Zhu, Jing; Shi, Hong-Min


    Objective: To observe the effect of Ho:YAG laser in treatment of urethra cauncle. Methods: The patients suffering from urethra cauncle were treated by Ho:YAG laser, the energy of per pulse is 0.5J. The frequency of pulse is 5~15Hz, and the average power of the laser is 2.5~7.5W. Results: Among the patients 188 cases of urethra cauncle were only cured for one time, twice for12 cases. No stricture on the peristome of urethra or urethrovaginal fistula was observed. Conclusions: The technique of treatment of urethra cauncle with Ho:YAG laser is an effect and safe therapeutics with the merit of excellent homeostasis, improved visualization, minimal thermal damage to surrounding tissue, shorter period of recovery and easy to operate. It is better than CO2 laser and Nd:YAG laser.

  4. Effect of Er:YAG laser energy on the morphology of enamel/adhesive system interface

    Delfino, Carina Sinclér; Souza-Zaroni, Wanessa Christine; Corona, Silmara Aparecida Milori; Pécora, Jesus Djalma; Palma-Dibb, Regina Guenka


    The aim of this study was to evaluate in vitro the influence of Er:YAG laser energy variation to cavity preparation on the morphology of enamel/adhesive system interface, using SEM. Eighteen molars were used and the buccal surfaces were flattened without dentine exposure. The specimens were randomly assigned to two groups, according to the adhesive system (conventional total-etching or self-etching), and each group was divided into three subgroups (bur carbide in turbine of high rotation, Er:YAG laser 250 mJ/4 Hz and Er:YAG laser 300 mJ/4 Hz) containing six teeth each. The enamel/adhesive system interface was serially sectioned and prepared for SEM. The Er:YAG laser, in general, produced a more irregular adhesive interface than the control group. For Er:YAG laser 250 mJ there was formation of a more regular hybrid layer with good tag formation, mainly in the total-etching system. However, Er:YAG laser 300 mJ showed a more irregular interface with amorphous enamel and fused areas, for both adhesive systems. It was concluded that cavity preparation with Er:YAG laser influenced on the morphology of enamel/adhesive system interface and the tissual alterations were more evident when the energy was increased.

  5. Comparison of laser iridotomy using short duration532-nm Nd: YAG laser (PASCAL) vs conventional laser in dark irides

    Hye; Jin; Chung; Hae-Young; Park; Su-Young; Kim


    AIM: To evaluate the outcome of laser iridotomy using532-nm Nd: YAG laser(PASCAL) with short pulse duration and Nd: YAG laser compared to conventional combined laser iridotomy.METHODS: Retrospective, nonrandomized, comparative case series. Forty-five eyes of 34 patients underwent laser iridotomy. Twenty-two eyes underwent iridotomy using short duration PASCAL and Nd: YAG laser, and 23 eyes underwent iridotomy using conventional combined laser method. The average settings of PASCAL were60 μm and 700-900 m W with a short duration of 0.01 s to reduce the total applied energy. The conventional laser was 50 μm and 700-900 m W for 0.1s. After photocoagulation with these laser, the Nd: YAG laser was added in each group. Endothelial cell counts of preiridotomy and 2mo after iridotomy were measured and compared.RESULTS: All eyes completed iridotomy successfully.The total energy used in the PASCAL group was 1.85 ±1.17 J. Compared to conventional laser 13.25 ±1.67 J, the energy used was very small due to the short exposure time of PASCAL. Endothelial cell counts were reduced by0.88% in the PASCAL group and 6.72% in the conventional laser group(P =0.044). The change in corneal endothelial cell counts before and after iridotomy was significant in conventional combined laser iridotomy group(P =0.004).CONCLUSION: Combined PASCAL and Nd:YAG laseriridotomy is an effective and safe technique in the dark brown irides of Asians. Furthermore, the short duration of exposure in PASCAL offers the advantages of reducing the total energy used and minimizing the corneal damage.

  6. Continuous-wave operation of a room-temperature Tm: YAP-pumped Ho: YAG laser


    We report a continuous-wave (CW) 2.1-μm Ho:YAG laser operating at room temperature pumped by a diode-pumped 1.94-?m Tm:YAP laser.The maximum output power of 1.5 W is obtained from Ho:YAG laser,corresponding to Tm-to-Ho slope efficiency of 17.9% and diode-to-He conversion efficiency of 5.6%.

  7. Effect of Er:YAG laser on enamel demineralization around restorations.

    Colucci, Vivian; de Souza Gabriel, Aline Evangelista; Scatolin, Renata Siqueira; Serra, Mônica Campos; Corona, Silmara Aparecida Milori


    This study evaluates in situ the effect of erbium-doped yttrium aluminum garnet (Er:YAG) laser parameters on the development of caries-like lesions adjacent to dental restorations. One hundred fifty bovine enamel slabs were randomly allocated among 15 volunteers. The specimens were subdivided into ten groups: nine experimental groups prepared with Er:YAG laser (300 mJ output, frequency of 2, 4 or 6 Hz, water flow rate of 2.0, 5.0, or 8.0 mL/min) and one control group (high-speed handpiece). The prepared cavity was restored with a composite resin, and the slabs were mounted on palatal appliance to be installed in the volunteers to the cariogenic challenge. After this, the specimens were sectioned to the longitudinal microhardness measurements. Data were submitted to Friedman and Wilcoxon paired tests. All groups prepared with Er:YAG laser demonstrated microhardness values higher than those prepared with high-speed handpiece, which showed the lowest microhardness values (24.86). The group prepared with Er:YAG laser (2 Hz-2.0 mL/min) showed the highest microhardness values (152.43), followed by those prepared with Er:YAG laser (2 Hz-5.0 mL/min) (133.08) and Er:YAG laser (2 Hz-8.0 mL/min) (91.61), respectively. The groups Er:YAG laser with 4 and 6 Hz of frequency and water flow rates of 2.0, 5.0, and 8.0 mL/min showed microhardness values lower than the groups cited above and showed statistical similarity among them. The Er:YAG laser parameters employed to cavity preparation influenced the acid resistance of the irradiated substrate, and the Er:YAG laser was capable to control the development of caries-like lesions around composite resin restorations.

  8. Analysis of the thermal effects in diode-pumped Tm:YAG ceramic slab lasers

    Cheng, Xiaojin; Shang, Jianhua; Jiang, Benxue


    Tm:YAG ceramics with a quasi-three-level system are sensitive to temperature. The optical and thermodynamic properties of Tm:YAG ceramics can change with changing temperature, and this affects the output power stability and beam quality of lasers. Thus temperature control is a key and difficult problem for Tm:YAG lasers, especially for high power laser output. In combination with slab structure and grad-doping techniques for composite ceramics, the temperature distributions of Tm:YAG ceramics are analyzed. It is found that the temperature difference of a rationally designed grad-doping Tm:YAG ceramic can be reduced significantly with the same absorption pump power, which results in higher output power and beam quality.

  9. Comparison of Dentin Permeability After Tooth Cavity Preparation with Diamond Bur and Er:YAG Laser

    Masoumeh Hasani Tabatabaei; Sara Shirmohammadi; Esmaeil Yasini; Mansoureh Mirzaei; Sakineh Arami; Hamid Kermanshah; Ladan Ranjbar Omrani; Azar Alimi; Nasim Chiniforush; Afrooz Nakhostin; Mahdi Abbasi


    Objectives: The aim of this study was to compare the permeability of dentin after using diamond bur and Er:YAG laser.Materials and Methods: Seventy-two recently extracted, intact, and restoration-free human permanent molars were used in this study. The samples were randomly divided into three groups of 24 each and class I cavities were prepared as follows. Group 1: High speed diamond bur with air and water spray. Group 2: Er:YAG laser. Group 3: Er:YAG laser followed by additional sub-ablative...

  10. Preserving a diffraction-limited beam in Ho:YAG laser using coherent polarization locking.

    Tan, L H; Chua, C F; Phua, P B


    We overcome several thermal issues present in Ho:YAG lasers by distributing the gain over a larger volume and achieve a diffraction-limited beam using coherent polarization locking. Increased single-pass absorption, suppression of output power saturation, and improvement in beam quality were shown using the coherent polarization locking technique as compared to a conventional Ho:YAG laser cavity with the same pump and cavity configuration. Ten watts of CW Ho:YAG laser power was generated with >96% coherent combining efficiency.

  11. Effect of Nd:YAG laser capsulotomy on refraction in multifocal apodized diffractive pseudophakia.

    Vrijman, V.; Linden, J.W.M. van der; Nieuwendaal, C.P.; Meulen, I.J. van der; Mourits, M.P.; Lapid-Gortzak, R.


    PURPOSE: To evaluate the effect on refraction of neodymium:YAG (Nd:YAG) laser posterior capsulotomy for posterior capsule opacification (PCO), and to evaluate the correlation between automated and subjective refraction in multifocal apodized diffractive pseudophakia. METHODS: A retrospective study

  12. Erbium:YAG laser as a method of deepithelization in corrective and reductive breast surgery.

    Trelles, Mario A; Pardo, Lourdes; Chamorro, Juan José; Bonanad, Enrique; Allones, Inés; Buil, Carmen; Luna, Ricardo


    Deepithelization of the breast in breast ptosis surgery is important, being associated with risks which could affect the clinical outcome. The role of Er:YAG laser deepithelization was investigated. A total of 12 bilateral mammoplasties were performed, randomly assigned to 2 groups, one of experienced and one of less-experienced surgeons. Results were compared between the 2 groups of surgeons for scalpel deepithelization on one breast and the Er:YAG laser on the contralateral breast. No complications; less edema, pain, and erythema; and quicker wound healing were observed in the laser-deepithelized breasts, with a shorter operation time even for the less-experienced surgeons. The authors do not suggest that the Er:YAG laser should replace the scalpel in the hands of the expert surgeon for breast deepithelization in breast ptosis surgery, but the results of the study suggest that Er:YAG laser ablation is a safe, precise, effective and complication-free method.

  13. Coherent polarization locking: an approach to mitigating optical damage in a pulsed Ho:YAG laser.

    Tan, L H; Chua, C F; Phua, P B


    Intracavity optical damage is mitigated in a pulsed Ho:YAG laser cavity using the coherent polarization locking (CPL) technique. By splitting the available pump power into two individual Ho:YAG laser rods, we passively coherently locked two orthogonal polarization lasers with 9.13 mJ output pulse energies and 14 ns pulsewidths, and operating at 800 Hz repetition rate. A conventional Ho:YAG laser cavity with the same pump and cavity configuration results in severe optical damage when operating at <2 kHz repetition rate, thus limiting the output pulse energies to <5 mJ. We also demonstrated, to the best of our knowledge, the first pulsed operation within the entire CPL Ho:YAG laser cavity by Q-switching in one of the polarization arms, producing nanosecond pulses with no sign of pulse instability.

  14. Narrow bandwidth Thomson photon source development using Laser-Plasma Accelerators

    Geddes, C. G. R.; van Tilborg, J.; Tsai, H.-E.; Toth, Cs.; Vay, J.-L.; Lehe, R.; Schroeder, C. B.; Esarey, E.; Rykovanov, S. G.; Grote, D. P.; Friedman, A.; Leemans, W. P.


    Compact, high-quality photon sources at MeV energies are being developed based on Laser-Plasma Accelerators (LPAs). An independent scattering laser with controlled pulse shaping in frequency and amplitude can be used together with laser guiding to realize high photon yield and narrow bandwidth. Simulations are presented on production of controllable narrow bandwidth sources using the beam and plasma capabilities of LPAs. Recent experiments and simulations demonstrate controllable LPAs in the energy range appropriate to MeV Thomson sources. Design of experiments and laser capabilities to combine these elements will be presented, towards a compact photon source system. A dedicated facility under construction will be described. Work supported by US DOE NNSA DNN R&D and by Sc. HEP under contract DE-AC02-05CH11231.

  15. Morphological assessment of dentine and cementum following apicectomy with Zekrya burs and Er:YAG laser associated with direct and indirect Nd:YAG laser irradiation.

    de Moura, Abilio Albuquerque Maranhão; Moura-Netto, Cacio; Barletta, Fernando Branco; Vieira-Júnior, Nilson Dias; Eduardo, Carlos de Paula


    This study aimed to assess the apical surface morphology of maxillary central incisors resected 3.0 mm from the tooth apex using Zekrya burs or Er:YAG laser, with or without subsequent direct Nd:YAG laser irradiation (apical and buccal surfaces) and indirect irradiation (palatal surface). Forty maxillary central incisors were instrumented and obturated. The roots were divided into 4 groups according to the root resection method (Zekrya bur or Er:YAG laser - 1.8 W, 450 mJ, 4 Hz, 113 J/cm(2)) and further surface treatment (none or Nd:YAG laser - 2.0 W, 100 mJ, 20 Hz, 124 J/cm(2)). The teeth were prepared for SEM analysis. Scores ranging from 1 to 4 were attributed to cut quality and morphological changes. The data were analyzed by the Kruskal-Wallis test and by Dunn's test. SEM images showed irregular surfaces on the apical portions resected with Zekrya burs, with smear layer and grooves in the resected dentine and slight gutta-percha displacement and plasticization. On the other hand, apicectomies carried out with Er:YAG laser showed morphological changes compatible with ablated dentine, with rough surfaces and craters. In spite of the presence of plasticized gutta-percha, with the presence of bubbles, an irregular adaptation of the filling material to the root walls was also observed. Direct Nd:YAG laser irradiation of the apical and buccal surfaces of the resected roots resulted in areas of resolidification and fusion in the dentine and cementum, with a vitrified aspect; indirect Nd:YAG laser irradiation of the palatal surfaces yielded a lower number of changes in the cementum, with irregular resolidification areas. There were no differences in terms of cut quality between the use of burs and Er:YAG laser or between the 2 surfaces (apical and buccal) treated with Nd:YAG laser with direct irradiation. However, morphological changes were significantly less frequent on surfaces submitted to indirect irradiation (palatal) when compared with those directly irradiated

  16. Treatment of dentinal tubules by Nd:YAG laser

    Chmelíčkova, Hana; Zapletalova, Zdeňka; Peřina, Jan, Jr.; Novotný, Radko; Kubínek, Roman; Stranyánek, Martin


    Symptom of cervical dentine hypersensitivity attacks from 10% to 15% of population and causes an uncomfortable pain during contact with any matter. Sealing of open dentinal tubules is one of the methods to reach insensibility. Laser as a source of coherent radiation is used to melt dentine surface layers. Melted dentine turns to hard mass with a smooth, non-porous surface. Simulation of this therapy was made in vitro by means of LASAG Nd:YAG pulsed laser system KLS 246-102. Eighty human extracted teeth were cut horizontally to obtain samples from 2 mm to 3 mm thick. First experiments were done on cross section surfaces to find an optimal range of laser parameters. A wide range of energies from 30 mJ to 210 mJ embedded in 0,3 ms long pulse was tested. Motion in X and Y axes was ensured by a CNC driven table and the pulse frequency 15 Hz was chosen to have a suitable overlap of laser spots. Some color agents were examined with the aim to improve surface absorption. Scanning Electron Microscopy was used to evaluate all samples and provided optimal values of energies around 50 Next experiments were done with the beam oriented perpendicularly to a root surface, close to the real situation. Optical fibers with the diameter of 0,6 mm and 0,2 mm were used to guide a laser beam to teeth surfaces. Laser processing heads with lens F = 100 mm and F = 50 mm were used. The best samples were investigated by means of the Atomic Force Microscopy.

  17. SEM investigation of Er:YAG laser apical preparation

    Bǎlǎbuc, Cosmin; Todea, Carmen; Locovei, Cosmin; RǎduÅ£ǎ, Aurel


    Endodontic surgery involves the incision and flap elevation, the access to the root tip, its resection, the cavity retrograde preparation and filling it with biocompatible material that provides a good seal of the apex[1]. Apicoectomy is compulsory in endodontic surgery. The final stage involves the root retropreparation and the carrying out of the retrograde obturation. In order to perform the retrograde preparation the endodontist can use various tools such as lowspeed conventional handpieces, sonic and ultrasonic equipment. The ideal depth of the preparation should be 3 mm, exceeding this value may affect the long-term success of the obturation [2]. Resection at the depth of 3 mm reduces apical ramifications by 98% and lateral root canals by 93%. The ultrasonic retropreparation has numerous advantages compared to the dental drill. Firstly, the cavity will be in the axis of the tooth which implies a minimum destruction of the root canal morphology. The preparations are precise, and the cutting pattern is perpendicular to the long axis of the root, the advantage being the reduction in the number of dentinal tubules exposed at the resected area [3]. Therefore, the retrograde filling is the procedure when an inert and non-toxic material is compacted in the apically created cavity.[4,5]. The Er:YAG laser is the most common wavelength indicated for dental hard tissue preparation. Its natural selectivity offers a significant advantage compared to the conventional hard tissue preparation [6-9].The purpose of this in vitro study was to investigate the quality of Er:YAG laser apical third preparation using Scanning Electron Microscopy (SEM), in comparison with the conventional ultrasonic method.

  18. Combination of CO2 and Q-switched Nd:YAG lasers is more effective than Q-switched Nd:YAG laser alone for eyebrow tattoo removal.

    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.

  19. High-gain Yb:YAG amplifier for ultrashort pulse laser at high-average power

    Vetrovec, John; Copeland, Drew A.; Litt, Amardeep S.; Du, Detao


    We report on a Yb:YAG laser amplifier for ultrashort pulse applications at kW-class average power. The laser uses two large-aperture, disk-type gain elements fabricated from composite ceramic YAG material, and a multi-pass extraction architecture to obtain high gain in a chirped-pulse amplification system. The disks are edge-pumped, thus allowing for reduced doping of host material with laser ions, which translates to lower lasing threshold and lower heat dissipation in the Yb:YAG material. The latter makes it possible to amplify a near diffraction-limited seed without significant thermo-optical distortions. This work presents results of testing the laser amplifier with relay optics configured for energy extraction with up to 40 passes through the disks. Applications for the ultrashort pulse laser amplifier include producing laser-induced plasma channel, laser material ablation, and laser acceleration of atomic particles.

  20. High-gain multipassed Yb:YAG amplifier for ultrashort pulse laser

    Vetrovec, John; Copeland, Drew A.; Litt, Amardeep S.; Du, Detao


    We report on a Yb:YAG laser amplifier for ultrashort pulse applications at kW-class average power. The laser uses two large-aperture, disk-type gain elements fabricated from composite ceramic YAG material, and a multi-pass extraction architecture to obtain high gain in a chirped-pulse amplification system. The disks are edge-pumped, thus allowing for reduced doping of the host material with laser ions, which translates to lower lasing threshold and lower heat dissipation in the Yb:YAG material. The latter makes it possible to amplify a near diffraction-limited seed without significant thermo-optical distortions. This work presents results of testing the laser amplifier with relay optics and passive polarization switching configured for energy extraction with up to 40 passes through the disks. Applications for the ultrashort pulse laser amplifier include producing a laser-induced plasma channel, laser material ablation, and laser acceleration of atomic particles.

  1. Effect of dental surface treatment with Nd:YAG and Er:YAG lasers on bond strength of resin composite to recently bleached enamel.

    Rocha Gomes Torres, Carlos; Caneppele, Taciana Marco Ferraz; Del Moral de Lazari, Regina; Ribeiro, Carolina Ferraz; Borges, Alessandra Buhler


    The aim of this work is to evaluate the effect of surface treatment with Er:YAG and Nd:YAG lasers on resin composite bond strength to recently bleached enamel. In this study, 120 bovine incisors were distributed into two groups: group C: without bleaching treatment; group B: bleached with 35% hydrogen peroxide. Each group was divided into three subgroups: subgroup N: without laser treatment; subgroup Nd: irradiation with Nd:YAG laser; subgroup Er: irradiation with Er:YAG laser. The adhesive system (Adper Single Bond 2) was then applied and composite buildups were constructed with Filtek Supreme composite. The teeth were sectioned to obtain enamel-resin sticks (1 × 1 mm) and submitted to microtensile bond testing. The data were statistically analyzed by the ANOVA and Tukey tests. The bond strength values in the bleached control group (5.57 MPa) presented a significant difference in comparison to the group bleached and irradiated with Er:YAG laser (13.18 MPa) or Nd:YAG (25.67 MPa). The non-bleached control group presented mean values of 30.92 MPa, with statistical difference of all the others groups. The use of Nd:YAG and Er:YAG lasers on bleached specimens was able to improve the bond strengths of them.

  2. Ablation of skin tissue by holmium:YAG laser

    Chen, Wei R.; Holt, Andrew; Nordquist, Robert E.


    Surface epithelial damage by Ho:YAG laser and recovery were studied using histology and electron microscopy. Rabbit skin was irradiated with fluence varying from 55 J/cm2 to 680 J/cm2. Laser damage was determined by histological measurement of three major injury indicators: surface lesion width, depth of photocoagulation, and depth of thermal damage. When the fluence increased, the surface lesion widened and the photocoagulation zone extended deeper into the dermis. The thermally damaged zone (60 degree(s)C muscle and nerve tissues appeared to remain intact under most of our irradiance except at 500 J/cm2 and greater. Thermally injured tissues began recovery within a short period and eventually returned to normal; electron microscopic findings indicated that severe swelling occurred in the individual collagen fibrils, but they were not disrupted and usually recovered to appear normal. A layer of new epithelium started growing underneath the photocoagulated zone around day 3. After 7 days, most photocoagulated tissue was partially, in some cases completely, separated from the skin by the new epithelium. The damage and recovery parameters established should aid in the clinical use of Holmium laser in treating lesions, benign or malignant, in hollow tubular organs and on surface epithelia.

  3. Er:YAG laser technology for remote sensing applications

    Chen, Moran; Burns, Patrick M.; Litvinovitch, Viatcheslav; Storm, Mark; Sawruk, Nicholas W.


    Fibertek has developed an injection locked, resonantly pumped Er:YAG solid-state laser operating at 1.6 μm capable of pulse repetition rates of 1 kHz to 10 kHz for airborne methane and water differential absorption lidars. The laser is resonantly pumped with a fiber-coupled 1532 nm diode laser minimizing the quantum defect and thermal loading generating tunable single-frequency output of 1645-1646 nm with a linewidth of tuning range covering multiple water absorption lines, with a pulse energy of 1 mJ and a pulse repetition frequency of 1 kHz. The resonator cavity was locked to the seed wavelength via a Pound Drever Hall (PDH) technique and an analog Proportional Integral Derivative (PID) Controller driving a high-bandwidth piezoelectric (PZT)-mounted cavity mirror. Two seed sources lasing on and off the methane absorption line were optically switched to tune the resonator wavelength on and off the methane absorption line between each sequential output pulse. The cavity locking servo maintained the cavity resonance for each pulse.

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

    Osman, Mai Abdel Raouf; Kassab, Ahmed Nazmi


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

  5. Thomson scattering measurement of a shock in laser-produced counter-streaming plasmas

    Morita, T.; Kuramitsu, Y.; Moritaka, T. [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan); Sakawa, Y.; Takabe, H. [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan); Graduate School of Science, Osaka University, 1-1 Machikane-yama, Toyonaka, Osaka 560-0043 (Japan); Tomita, K.; Nakayama, K.; Inoue, K.; Uchino, K. [Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1, Kasugakoen, Kasuga, Fukuoka 816-8580 (Japan); Ide, T.; Tsubouchi, K. [Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); Nishio, K.; Ide, H.; Kuwada, M. [Graduate School of Science, Osaka University, 1-1 Machikane-yama, Toyonaka, Osaka 560-0043 (Japan)


    We report the first direct measurement of temporally and spatially resolved plasma temperatures at a shock as well as its spatial structure and propagation in laser-produced counter-streaming plasmas. Two shocks are formed in counter-streaming collisionless plasmas early in time, and they propagate opposite directions. This indicates the existence of counter-streaming collisionless flows to keep exciting the shocks, even though the collisional effects increase later in time. The shock images are observed with optical diagnostics, and the upstream and downstream plasma parameters of one of the shocks are measured using Thomson scattering technique.

  6. Development of the so-called third stage laser Thomson scattering diagnostics of plasmas

    Muraoka, Katsunori; Yamagata, Yukihiko; Hisano, Taishi; Uchino, Kiichirou; Miyazaki, Koichi


    In the recent review article,^1) we indicated that the incoherent laser Thomson scattering (LTS) diagnostics of plasmas for measurements of electron densities and temperatures (or more generally EEDFs) be classified as having evolved from the first stage where a whole Thomson spectrum be obtained during a single laser pulse from plasmas having electron density of above 10^18 m-3, through the second stage where data accumulation be prerequisite for ne below 10^18 m-3, and to the third stage where a strong suppression of stray light in addition to the data accumulation be necessary to measure at an extremely small size of less than 100 μm near to material surfaces. The third stage LTS was first demonstrated for a PDP (plasma display panel)-like discharge three years ago employing a triple grating polychromator. In order to further expand its applicable ranges, we are pursuing a more general approach by taking into account such factors as laser divergence, stray light suppression and other aspects. The present status is presented. 1) K. Muraoka, K. Uchino, Y. Yamagata, Y. Noguchi, M. Mansour, P. Suanpoot, S. Narishige, and M. Noguchi, Plasma Sources Sci. Technol. 11 (2002) A143.

  7. Thomson backscattering from laser generated, relativistically moving high-density electron layers

    Paz, Athena E; Rödel, Christian; Schnell, Michael; Jäckel, Oliver; Kaluza, Malte C; Paulus, Gerhard G


    We show experimentally that XUV radiation is produced when a laser pulse is Thomson backscattered from sheets of relativistic electrons which are formed at the rear-surface of a foil irradiated on its front side by a high-intensity laser. An all-optical setup is realized using the Jena Titanium:Sapphire TW laser system (JETI). The main pulse is split into two pulses: one to accelerate electrons from thin aluminum foil targets to energies of the order of some MeV and the other, counterpropagating probe pulse is Thomson-backscattered off these electrons when they exit the target rear side. The process produced photons within a wide spectral range of some tens of eV as a result of the broad electron energy distribution. The highest scattering intensity is observed when the probe pulse arrives at the target rear surface 100 fs after the irradiation of the target front side by the pump pulse, corresponding to the maximum flux of hot electrons at the interaction region. These results can provide time-resolved infor...

  8. Generation of 170-fs Laser Pulses at 1053 nm by a Passively Mode-Locked Yb:YAG Laser

    ZHOU Bin-Bin; WEI Zhi-Yi; LI De-Hua; TENG Hao; Bourdet G. L


    A novel method is developed to obtain 1.05μm laser operation with a Yb:YAG laser. By using a Yb:YAG crystal with proper length and doping concentration, a femtosecond Yb: YAG laser is realized at the central wavelength of 1053nm. The measured pulse duration and spectral bandwidth (FWHM) are 17ors and 7nm; the repetition rate is 80 MHz. Under a power pump of 2 W, an average mode-locking power of 180mW is achieved.

  9. Nd: YAG Laser Treatment for Keloids and Hypertrophic Scars: An Analysis of 102 Cases

    Sachiko Koike, MD


    Conclusions: Hypertrophic scars responded significantly better to 1064 nm Nd:YAG laser treatment than keloids. However, keloid recurrence occurred when there was remaining redness and induration, even if only a small part of the scar was affected.

  10. Demonstration of X-ray Thomson Scattering on Shenguang-Ⅱ Laser Facility

    胡广月; 张小丁; 郑坚; 雷安乐; 沈百飞; 徐至展; 张继彦; 杨家敏; 杨国洪; 韦敏习; 李军; 丁永坤


    X-ray Thomson scattering technique for diagnosing dense plasma was demonstrated on Shenguang-Ⅱ laser facility. Laser plasma x-ray source of titanium He-a lines (-4.75 keV), generated by laser beam (1.5 kJ/527 nm/2 ns) heated titanium thin foil, was used as x-ray probe beam. The x-ray probe was then scattered by cold CH foam column of 1 g/cm^3 density. The scattered radiation at 90° was diffracted by polyethylene terephthalate (PET) crystal and recorded on x-ray charge-coupled device. Well-defined scattering spectra were obtained with good signal to noise ratio.

  11. Laser Thomson scattering diagnostics of non-equilibrium high pressure plasmas

    Muraoka, K.; Uchino, K.; Bowden, M.D.; Noguchi, Y. [Kyushu Univ., Fukuoka (Japan). Interdisciplinary Graduate School of Engineering Sciences


    For various applications of non-equilibrium high pressure plasmas, knowledge of electron properties, such as electron density, electron temperature and/or electron energy distribution function (eedf), is prerequisite for any rational approach to understanding physical and chemical processes occurring in the plasmas. For this purpose, laser Thomson scattering has been successfully applied for the first time to measure the electron properties in plasmas for excimer laser pumping and in microdischarges. Although this diagnostic technique is well established for measurements in high temperature plasmas, its applications to these glow discharge plasmas have had various inherent difficulties, such as a presence of high density neutral particles (>10{sup 21} m{sup -3}) in the excimer laser pumping discharges and an extremely small plasma size (<0.1 mm) and the presence of nearby walls for microdischarges. These difficulties have been overcome and clear signals have been obtained. The measured results are presented and their implications in the respective discharge phenomena are discussed.

  12. Er:YAG laser for the surgical treatment of the carpal tunnel syndrome

    Russ, Detlef; Ebinger, Thomas; Illich, Wolfgang; Steiner, Rudolf W.


    We developed a new surgical procedure to improve the recurrence rate using an Er:YAG laser as dissection tool for the carpal ligament with the objective to ablate a small amount of the carpal ligament and to denaturate its ends. The Er:YAG Laser was transmitted to the applicator via a GeO fiber. With this system we proceeded 10 carpal ligament dissections without any complications in the follow-up period. All patients were free of pain and recurrence.

  13. Q-switched pulse laser generation from double-cladding Nd:YAG ceramics waveguides.

    Tan, Yang; Luan, Qingfang; Liu, Fengqin; Chen, Feng; Vázquez de Aldana, Javier Rodríguez


    This work reports on the Q-switched pulsed laser generation from double-cladding Nd:YAG ceramic waveguides. Double-cladding waveguides with different combination of diameters were inscribed into a sample of Nd:YAG ceramic. With an additional semiconductor saturable absorber, stable pulsed laser emission at the wavelength of 1064 nm was achieved with pulses of 21 ns temporal duration and ~14 μJ pulse energy at a repetition rate of 3.65 MHz.

  14. The Effects of Er:YAG, Nd:YAG, and Ho:YAG Laser Surface Treatments to Acrylic Resin Denture Bases on the Tensile Bond Strength of Silicone-Based Resilient Liners.

    Gorler, Oguzhan; Dogan, Derya Ozdemir; Ulgey, Melih; Goze, Aysegul; Hubbezoğlu, Ihsan; Zan, Recai; Ozdemir, Ali Kemal


    The present study was to assess the effect of surface treatments of Er:YAG, Nd:YAG, and Ho:YAG lasers on the tensile bond strength of a silicone-based resilient liner to an acrylic denture in an in vitro setting. Experimental dumbbell-shaped specimens (75 mm) were produced by combining two acrylate pieces fabricated from heat-polymerized acrylic resin (36 mm) with 3 mm of Molloplast(®)-B filling between them. The specimens (n=200) were randomly divided in half for thermocycling, and each 100 specimen set was randomized into five groups (n=20) with different surface treatments: control (no surface treatment), sandblasting, Er:YAG laser, Nd:YAG laser, and Ho:YAG laser. A tensile bond strength test was performed. The effect of the laser surface treatments was examined with scanning electron microscopy. Only the Er:YAG laser increased the tensile bond strength compared with the other treatments. The other laser groups showed lower bond strengths. The Ho:YAG laser resulted in considerably reduced tensile bond strength. The scanning electron microscopy images showed that applying laser surface treatments modified the surface of the denture base resin. There was not an overall improvement with the use of the studied laser modalities in the adhesion quality of resilient denture liner to acrylic resin, although Er:YAG laser showed a potential to improve their adhesion. These laser modalities need to be subjected to further studies to determine optimal setup for use in prosthodontics.

  15. Tunable Sum Frequency Mixing of a Ti∶sapphire Laser and a Nd∶YAG Laser

    DING Xin; YAO Jianquan; YU Yizhong; YU Xuanyi; XU Jingjun; ZHANG Guangyin


    In this paper the theoretical and experimental results of sum-frequency mixing of a Ti∶sapphire laser and a 1.064 μm Nd∶YAG laser are presented. By using two KTP crystals cut at θ=76° and 85° (φ=90° in both crystals), respectively, the sum-frequency mixing tuning range from 459.3 to 509.6 nm in one Ti∶sapphire laser setup is experimentally achieved. The maximum output energy was 14.6 mJ and the energy conversion efficiency was up to 15.2%.

  16. Polarization properties of laser-diode-pumped micro-grained Nd:YAG ceramic lasers

    Otsuka, Kenju


    Detailed polarization properties have been examined in laser-diode-pumped (LD-pumped) micro-grained ceramic Nd:YAG lasers in different microchip cavity configurations. Stable linearly-polarized single-frequency oscillations, whose polarization direction coincides with that of an LD pump light, were observed in an external cavity scheme. While, in the case of a thin-slice laser scheme with coated reflective ends, elliptically-polarized single-frequency operations took place in the low pump-power regime and dynamic instabilities appeared, featuring self-induced antiphase modulations among counter-rotating circularly-polarized components belonging to the same longitudinal mode, with increasing the pump power

  17. Er:YAG laser irradiation to control the progression of enamel erosion: an in situ study.

    Scatolin, R S; Colucci, V; Lepri, T P; Alexandria, A K; Maia, L C; Galo, R; Borsatto, M C; Corona, S A M


    This in situ study evaluated the effect of Er:YAG laser irradiation in controlling the progression of enamel erosion-like lesions. Fifty-six enamel slabs (330 KHN ± 10 %) with one fourth of the surface covered with resin composite (control area) were submitted to initial erosion-like lesion formation with citric acid. The slabs were divided into two groups: irradiated with Er:YAG laser and non-irradiated. Fourteen volunteers used an intraoral palatal appliance containing two slabs, in two phases of 5 days each. During the intraoral phase, in a crossed-over design, half of the volunteers immersed the appliance in citric acid while the other half used deionized water, both for 5 min, three times per day. Enamel wear was determined by an optical 3D profilometer. ANOVA revealed that when deionized water was used as immersion solution during the intraoral phase, lower values of wear were showed when compared with the groups that were eroded with citric acid, whether irradiated or non-irradiated with Er:YAG laser. When erosion with citric acid was performed, Er:YAG laser was not able to reduce enamel wear. Small changes on enamel surface were observed when it was irradiated with Er:YAG laser. It may be concluded that Er:YAG laser irradiation did not reduce the progression of erosive lesions on enamel submitted to in situ erosion with citric acid.

  18. Adhesion of composite luting cement to Er:YAG-laser-treated dentin.

    Carrieri, Teresa C D; de Freitas, Patricia M; Navarro, Ricardo S; Eduardo, Carlos de P; Mori, Matsuyoshi


    Although some studies claim to the increase of composite resin adhesion to Er:YAG-laser-treated dentin, there are still no reports on the adhesion of composite resin cements to the irradiated surface. This in vitro study evaluated the tensile bond strength (TBS) of a composite resin cement to dentin treated with the Er:YAG laser. Sixty human dentin samples were divided into four groups (n = 15): G1 (Control)-no treatment; G2-Er:YAG laser 60 mJ, 2 Hz, with water cooling, non-contact (19 J/cm(2)); G3-Er:YAG laser 60 mJ, 10 Hz, 50/10 fiber, contact, without water cooling (40 J/cm(2)); G4-Er:YAG laser 60 mJ, 10 Hz, 50/10 fiber, contact, with water cooling (40 J/cm(2)). After the surface treatment, each sample was submitted to bonding procedures. The analysis of variance (ANOVA) and Tukey tests revealed no statistical significant difference on TBS values for groups G1 (13.73 +/- 3.05 MPa), G2 (12.60 +/- 2.09 MPa) and G4 (11.17 +/- 4.04 MPa). G4 was not statistically different from G3 (8.64 +/- 2.06 MPa). Er:YAG laser irradiation with different settings can constitute an alternative tool to the use of composite resin-luting cements.

  19. Ignition of an automobile engine by high-peak power Nd:YAG/Cr⁴⁺:YAG laser-spark devices.

    Pavel, Nicolaie; Dascalu, Traian; Salamu, Gabriela; Dinca, Mihai; Boicea, Niculae; Birtas, Adrian


    Laser sparks that were built with high-peak power passively Q-switched Nd:YAG/Cr(4+):YAG lasers have been used to operate a Renault automobile engine. The design of such a laser spark igniter is discussed. The Nd:YAG/Cr(4+):YAG laser delivered pulses with energy of 4 mJ and 0.8-ns duration, corresponding to pulse peak power of 5 MW. The coefficients of variability of maximum pressure (COV(Pmax)) and of indicated mean effective pressure (COV(IMEP)) and specific emissions like hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NO(x)) and carbon dioxide (CO2) were measured at various engine speeds and high loads. Improved engine stability in terms of COV(Pmax) and COV(Pmax) and decreased emissions of CO and HC were obtained for the engine that was run by laser sparks in comparison with classical ignition by electrical spark plugs.

  20. Investigation of two-frequency Nd{sup 3+} : YAG laser

    Arapov, Yu D; Ivanov, A F; Kas' yanov, I V; Magda, L E [E.I. Zababakhin All-Russian Scientific-Research Institute of Technical Physics, Russian Federal Nuclear Centre, Snezhinsk, Chelyabinsk region (Russian Federation)


    A repetitively pulsed two-frequency laser is developed. Pulsed operation of a laser based on a Nd{sup 3+} : YAG crystal with simultaneous amplification of radiation at two wavelengths in a single-pass amplifier is studied. (laser optics 2012)

  1. Study on 660-nm quasi-continuous-wave intracavity frequency-doubled Nd:YAG laser

    Tao Wang(王涛); Jianquan Yao(姚建铨); Baigang Zhang(张百钢); Guiyan Zang(臧贵艳); Peng Wang(王鹏); Yizhong Yu(于意仲)


    A quasi-continuous-wave intracavity frequency-doubled Nd:YAG laser which operates at 660 nm is studied.By using a flat-flat laser cavity, 2 Kr-lamps, KTP crystal and an acousto-optically Q-switch, 2-W outputpower at 660 nm is obtained. The relationship between laser cavity length and output power is analyzed.

  2. Er:YAG and alexandrite laser radiation propagation in root canal and its effect on bacteria.

    Jelínková, H; Dostálová, T; Dusková, J; Krátký, M; Miyagi, M; Shoji, S; Sulc, J; Nemec, M


    The objective of this study was to compare the bactericidal effect of the Er:YAG (wavelength 2.94 microm) and the Alexandrite (wavelength 0.75 microm) laser radiation. The spreading laser energy in the surrounding hard dental tissues round the root canal was evaluated and the bactericidal effect of both these different laser wavelengths was analyzed. The use of a laser to clean and shape the root canal space is the latest method used for cleaning of root canals. The interest in laser endodontics was concentrated on the possibility to extirpate the contents of the root canal, to sterilize and to "melt" the walls of the root canals. The previous reports were performed with CO2, excimer, argon, Nd:YAG, Ho:YAG, and Er:YAG lasers. Er:YAG laser system (2.94 microm, energy 100 mJ or 300 mJ, repetition rate 1 Hz, 30 pulses) and alexandrite laser system (0.75 microm, energy 250 mJ, repetition rate 1 Hz, 30 pulses) were prepared and three experimental arrangements were used during the measurements. First the energy transport through the tooth tissue was observed (frontal and side experimental setups) and then, the bactericidal effect was evaluated. It was demonstrated that due to the absorption in the hydroxyapatite and water content in the dentin, the Er:YAG laser radiation is fully absorbed in the root canal wall. This direct influence of the radiation could be expected only close to the sapphire tip. It was found that the tissue, which was not directly affected by the laser radiation, cannot be disinfected by the subablative effect of Er:YAG laser radiation. In the second part of the experiment the real bactericidal effect of Er:YAG ablative energy (300 mJ) could be observed. It was also shown that the alexandrite laser radiation with a wavelength of 0.75 microm spreads through the canal system space and leaks into the surrounding tooth tissues. Both lasers have bactericidal effect. The pulsed Er:YAG and alexandrite lasers can be efficiently used for killing dental

  3. Optic coherence tomography measurement of choroidal and retinal thicknesses after uncomplicated YAG laser capsulotomy

    İsa Yuvacı


    Full Text Available ABSTRACT Purpose: Optic coherence tomography (OCT evaluation of the choroid, retina, and retinal nerve fiber layer after uncomplicated yttrium-aluminum-garnet (YAG laser capsulotomy. Methods: OCT analysis of retinal and choroidal structures was performed in 28 eyes of 28 patients following routine examinations before and 24 h, 72 h, 2 weeks, 4 weeks, and 12 weeks after YAG laser capsulotomy. Data were analyzed using the SPSS software. Results: Data collected before YAG capsulotomy and at the above mentioned follow-up visits are summarized as follows. Mean central subfoveal choroidal thickness before YAG capsulotomy was 275.85 ± 74.78 µm; it was 278.46 ± 83.46 µm, 283.39 ± 82.84 µm, 280.00 ± 77.16 µm, 278.37 ± 76.95 µm, and 278.67 ± 76.20 µm after YAG capsulotomy, respectively. Central macular thickness was 272.14 ± 25.76 µm before YAG capsulotomy; it was 266.53 ± 26.47 µm, 269.14 ± 27.20 µm, 272.17 ± 26.97 µm, 270.91 ± 26.79 µm, and 273 ± 26.63 µm after YAG capsulotomy, respectively. Mean retinal nerve fiber layer thickness before YAG was 99.89 ± 7.61 µm; it was 98.50 ± 8.62 µm, 98.14 ± 8.69 µm, 99.60 ± 8.39 µm, 99.60 ± 8.39 µm, and 99.60 ± 8.35 µm after YAG capsulotomy, respectively. No observed change was statistically significant. No significant changes were observed with regard to mean intraocular pressure. Conclusions: After YAG laser capsulotomy, no statistically significant changes were found in choroidal, retinal, and optical nerve fiber layer thicknesses, although slight thickness changes in these structures were observed, particularly during the first days.

  4. Combined pulsed dye laser and fiberoptic Nd-YAG laser for the treatment of hypertrophic port wine stain.

    Radmanesh, Mohammed; Radmanesh, Ramin


    The hypertrophic Port Wine Stain (PWS) is only partially and superficially treated with the Pulsed dye laser (PDL) because of its limited depth of penetration. We used combined PDL and fiberoptic 1444-nm Nd-YAG laser to treat a case with hypertrophic PWS. After tumescent anesthesia, few holes were made by a 16-gauge needle on different sides of the lesion. The fiberoptic tip of 1444-nm Nd-YAG laser was inserted within the holes and was pushed forward while triggering. In a fan pattern and by a back and forth movement, the subcutaneous and deep dermal areas were coagulated. The skin and outer mucosal surfaces were then treated by PDL. The fiberoptic system used was Accusculpt 1444-nm Nd-YAG laser (Lutronic lasers, South Korea), and the PDL used was 585 nm Nlite system (Chromogenex UK). The parameters used for PDL were fluence = 9 Joules/cm(2) and the spot size was 5 mm. The parameters used for fiberoptic 1444-nm Nd-YAG laser were: Pulse rate = 30 Hz, pulse energy = 300 mJ, power = 6 W, and the total energy = 4000 J for the whole face and mucosa. Little sign of regression and moderate purpura were detected immediately after combined fiberoptic Nd-YAG and PDL therapy. The lesion gradually regressed within 4 months with satisfactory color and volume change. Combined fiberoptic Nd-YAG laser and PDL can be used for the treatment of deeper and superficial layers of hypertrophic PWS.




    Full Text Available BACKGROUND: Nd: YAG laser is non-invasive and effective means to deal with the posterior capsule opacification. However safe it may have some inherent complications. Rise of intraocular pressure is frequently encountered and incompletely understood complication of YAG laser capsulotomy and documented with conflicting results. AIMS: Purpose of the study to assess the efficacy of YAG laser capsulotomy in term of visual outcome and also study the complications of the procedure, particularly on IOP. SETTING: Tertiary Centre. DESIGN: Prospective interventional study. MATERIAL AND METHODS: Present study evaluate the changes in IOP and visual acuity after Nd-YAG laser capsulotomy in 280 eyes with significant PCO after uncomplicated small incision cataract surgery with IOL implantation. Complete ocular examination including visual acuity, anterior segment examination with slit lamp, fundus and application tonometry were performed pre-and post-laser in all cases. Posterior capsulotomy was done with Q-switched Nd: YAG laser with energy used 10 mmHg was found in 5% of cases. Ninety two percent patients achieved base line pressure within 4 hours. Incidence of minor complications was 14.6% and none of patient showed major complications or deterioration of vision. CONCLUSION: Our study showed insignificant rise in IOP, and none of patient show vision threatening complication after laser capsulotomy. Hence routine antiglaucoma medicine may not be necessary in all patients following Nd: YAD laser capsulotomy.

  6. A Continuous-Wave Diode-Side-Pumped Tm:YAG Laser with Output 51 W

    ZHANG Xiao-Fu; CUI DaFu; XU Zu-Yan; XU Yi-Ting; LI Cheng-Ming; ZONG Nan; XU Jia-Lin; CUI Qian-Jin; LU Yuan-Fu; BO Yong; PENG Qin-Jun


    A compact diode-side-pumped Tm:YAG laser is presented, which can output 51 W of cw power at 2.02μm. The Tm:YAG rod is side pumped by nine diode arrays with the central wavelength of 783nm and the with bandwidth of about 2.5 nm at 25℃. To decrease the thermal effect on the both ends and dissipate the heat effectively, one composite Tm:YAG rod with the undoped YAG end caps and the screw threads on the side surface of the rod is used as the laser crystal. The maximum optical-to-optical conversion efficiency of the 2.02-μm laser output is 14.2%, with a slope efficiency of 26.8%.

  7. Laser emission from diode-pumped Nd:YAG ceramic waveguide lasers realized by direct femtosecond-laser writing technique.

    Salamu, Gabriela; Jipa, Florin; Zamfirescu, Marian; Pavel, Nicolaie


    We report on realization of buried waveguides in Nd:YAG ceramic media by direct femtosecond-laser writing technique and investigate the waveguides laser emission characteristics under the pump with fiber-coupled diode lasers. Laser pulses at 1.06 μm with energy of 2.8 mJ for the pump with pulses of 13.1-mJ energy and continuous-wave output power of 0.49 W with overall optical efficiency of 0.13 were obtained from a 100-μm diameter circular cladding waveguide realized in a 0.7-at.% Nd:YAG ceramic. A circular waveguide of 50-μm diameter yielded laser pulses at 1.3 μm with 1.2-mJ energy.

  8. A gated Thomson parabola spectrometer for improved ion and neutral atom measurements in intense laser produced plasmas

    Tata, Sheroy; Mondal, Angana; Sarkar, Soubhik; Lad, Amit D.; Krishnamurthy, M.


    Ions of high energy and high charge are accelerated from compact intense laser produced plasmas and are routinely analysed either by time of flight or Thomson parabola spectrometry. At the highest intensities where ion energies can be substantially large, both these techniques have limitations. Strong electromagnetic pulse noise jeopardises the arrival time measurement, and a bright central spot in the Thomson parabola spectrometer affects the signal to noise ratio of ion traces that approach close to the central spot. We present a gated Thomson parabola spectrometer that addresses these issues and provides an elegant method to improvise ion spectrometry. In addition, we demonstrate that this method provides the ability to detect and measure high energy neutral atoms that are invariably present in most intense laser plasma acceleration experiments.

  9. Three-dimensional topographic scanning electron microscope and Raman spectroscopic analyses of the irradiation effect on teeth by Nd:YAG, Er: YAG, and CO(2) lasers.

    Yamada, Magda K; Uo, Motohiro; Ohkawa, Shoji; Akasaka, Tsukasa; Watari, Fumio


    A three-dimensional analyzer installed in a scanning electron microscope was used to evaluate the morphology and surface roughness using noncontact profilometry. Observations were carried out on the enamel and dentin surface irradiated by three different lasers: Nd:YAG (wavelength 1.06 microm), Er:YAG (2.94 microm), and CO(2) (10.6 microm). Spectroscopic analysis was done by Raman spectroscopy for nonirradiated and laser-irradiated surfaces. The lasers were applied perpendicularly to vertically sectioned and polished human extracted caries-free molars. The tooth was sectioned at each cavity for cross-section analysis after laser irradiation. Irradiation by Nd:YAG and CO(2) lasers of the enamel surface showed an opaque white color, different from dentin where the surface turned black. The Er:YAG laser induced no changes in color of the dentin. Numerous cracks associated with thermal stress were observed in the CO(2) laser-irradiated dentin. Noncontact surface profile analysis of Er:YAG laser-irradiated enamel and dentin showed the deepest cavities, and direct cross-sectional observations of them showed similar cavity outlines. The CO(2) laser-irradiated dentin had the least surface roughness. Raman spectroscopic analysis showed that fluorescence from the laser-irradiated tooth was generally greater than from nonirradiated teeth. Bands in dentin attributed to organic collagen matrix were lost after Nd:YAG and CO(2) laser irradiation, and a broad peak due to amorphous carbon appeared. The Er:YAG laser-irradiated dentin showed no sign of a carbon band and had more suitable results for dental ablation. Noncontact surface profile analysis was effective to evaluate the structural change in the tooth in the microarea of study after laser irradiation.

  10. Development of Thomson scattering system on Shenguang-III prototype laser facility

    Gong, Tao [CAS Key Laboratory of Geospace Environment and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang, Sichuan 621900 (China); Li, Zhichao; Jiang, Xiaohua; Ding, Yongkun, E-mail:; Yang, Dong; Wang, Zhebin; Wang, Fang; Li, Ping; Liu, Shenye; Jiang, Shaoen [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang, Sichuan 621900 (China); Hu, Guangyue; Zhao, Bin [CAS Key Laboratory of Geospace Environment and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zheng, Jian, E-mail: [CAS Key Laboratory of Geospace Environment and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240 (China)


    A Thomson scattering diagnostic system, using a 263 nm laser as the probe beam, is designed and implemented on Shenguang-III prototype laser facility. The probe beam is provided by an additional beam line completed recently. The diagnostic system allows simultaneous measurements of both ion feature and red-shifted electron feature from plasmas in a high-temperature (≥2 keV) and high-density (≥10{sup 21} cm{sup −3}) regime. Delicate design is made to satisfy the requirements for successful detection of the electron feature. High-quality ion feature spectra have already been diagnosed via this system in recent experiments with gas-filled hohlraums.

  11. X-ray Thomson scattering measurements from hohlraum-driven spheres on the OMEGA laser

    Saunders, A. M.; Jenei, A.; Döppner, T.; Falcone, R. W.; Kraus, D.; Kritcher, A.; Landen, O. L.; Nilsen, J.; Swift, D.


    X-ray Thomson scattering (XRTS) is a powerful diagnostic for probing warm and hot dense matter. We present the design and results of the first XRTS experiments with hohlraum-driven CH2 targets on the OMEGA laser facility at the Laboratory for Laser Energetics in Rochester, NY. X-rays seen directly from the XRTS x-ray source overshadow the elastic scattering signal from the target capsule but can be controlled in future experiments. From the inelastic scattering signal, an average plasma temperature is inferred that is in reasonable agreement with the temperatures predicted by simulations. Knowledge gained in this experiment shows a promising future for further XRTS measurements on indirectly driven OMEGA targets.

  12. Composite fillings microleakage after TEM00 Er: YAG laser texturing of human tooth enamel surface

    Belikov, A. V.; Shatilova, K. V.; Skrypnik, A. V.; Fedotov, D. Y.


    The results of comparative investigation of methylene-blue microleakage between tooth enamel surface and light-cure composites various fluidity are presented. An enamel surface was treated by traditional methods or laser method (laser texturing). The role of adhesive systems is investigated at enamel texturing by the TEM00 Er: YAG radiation. It is shown, that microleakage was not observed when enamel was textured by the TEM00 Er: YAG laser radiation and covered with flowable composite "Revolution" (Kerr) without adhesive system. It is established, that for laser textured surfaces methylene-blue microleakage depends on distance between microcraters.

  13. Wound healing after irradiation of bone tissues by Er:YAG laser

    Watanabe, Hisashi; Yoshino, Toshiaki; Aoki, Akira; Ishikawa, Isao


    Clinical applications of Er:YAG laser are now developing in periodontics and restorative dentistry. To date, there have been few studies indicating safety criteria for intraoral usage of the Er:YAG laser. The present study examined the effects of the Er:YAG laser on bone tissues, supposing mis- irradiation in the oral cavity during dental application, especially periodontal surgery. The experiments were performed using the newly-developed Er:YAG laser apparatus equipped with a contact probe. In experiment 1, 10 pulses of laser irradiation were administered to the parietal bone of a rat at 50, 150 and 300 mJ/pulse with and without water irrigation, changing the irradiation distance to 0, 5, 10 and 20 mm, respectively. As a control, electric knife was employed. Macroscopic and SEM observations of the wound surface were performed. In experiment 2, laser irradiation in a straight line was performed at 150 mJ/pulse, 1- pps and 0,5, 10 mm irradiation distance without water irrigation. Wound healing was observed histologically at 0, 3, 7, 14 and 28 days after laser irradiation and compared with that of the control. Non-contact irradiation by Er:YAG laser did not cause severe damage to the parietal bone tissue under water irrigation. Contact irradiation induced a limited wound, however, new bone formation was observed 28 days after laser irradiation, while osseous defect with thermal degenerative tissue remained at the control site. In conclusion, irradiation with an Er:YAG laser would not cause severe damage to surrounding bone tissues in the oral cavity when used within the usual power settings for dental treatment. Furthermore, this laser may be applicable for osseous surgery because of its high ablation efficiency and good wound healing after irradiation.

  14. Sheet metal welding using a pulsed Nd: YAG laser-robot

    Huang, Qi; Kullberg, Gunnar; Skoog, Hans

    This paper presents a pulsed Nd: YAG laser-robot system for spot and seam welding of mild steel sheets. The study evaluates the laser beams behaviour for welding, and then investigates pulsed Nd: YAG laser spot and seam welding processes. High pulse power intensity is needed to initiate the key-hole welding process and a threshold pulse energy to reach full penetration. In seam welding, a weld consists of successive overlapping spots. Both high pulse energy and high average power are needed to keep the key-hole welding going. A 70% overlap is used to define overlapping spot welding as seam welding and to optimize process parameters because a high tensile strength joint compatible with the strength of the base material can be obtained when the overlap is ≥ 70%; at the same time a smooth seam with full penetration is obtained. In these cases, the joints in pulsed Nd: YAG laser welding are comparable in strength to those obtained with CO 2 laser welding. Robot positioning and motion accuracies can meet the demands of Nd: YAG laser sheet metal welding, but its cornering accuracy affects the welding processes. The purpose of the study is to evaluate the YAG laser-robot system for production in the automotive industry.

  15. Optimizing treatment parameters for the vascular malformations using 1064-nm Nd:YAG laser

    Gong, Wei; Lin, He; Xie, Shusen


    Near infrared Nd:YAG pulsed laser treatment had been proved to be an efficient method to treat large-sized vascular malformations like leg telangiectasia for deep penetrating depth into skin and uniform light distribution in vessel. However, optimal clinical outcome was achieved by various laser irradiation parameters and the key factor governing the treatment efficacy was still unclear. A mathematical model in combination with Monte Carlo algorithm and finite difference method was developed to estimate the light distribution, temperature profile and thermal damage in epidermis, dermis and vessel during and after 1064 nm pulsed Nd:YAG laser irradiation. Simulation results showed that epidermal protection could be achieved during 1064 nm Nd:YAG pulsed laser irradiation in conjunction with cryogen spray cooling. However, optimal vessel closure and blood coagulation depend on a compromise between laser spot size and pulse duration.

  16. TEM00 mode Nd:YAG solar laser by side-pumping a grooved rod

    Vistas, Cláudia R.; Liang, Dawei; Almeida, Joana; Guillot, Emmanuel


    A simple TEM00 mode solar laser system with a grooved Nd:YAG rod pumped through a heliostat-parabolic mirror system is reported here. The radiation coupling capacity of a fused silica tube lens was combined with the multipass pumping ability of a 2 V-shaped cavity to provide efficient side-pumping along a 4.0 mm diameter grooved Nd:YAG single-crystal rod. TEM00 mode solar laser power of 3.4 W was measured by adopting an asymmetric large-mode laser resonant cavity. Record TEM00 mode solar laser collection efficiency of 3.4 W/m2and slope efficiency of 1.9% was achieved, which corresponds to 1.8 and 2.4 times more than the previous TEM00 mode Nd:YAG solar laser using the PROMES-CNRS heliostat-parabolic mirror system, respectively.

  17. Towards high-quality optical ceramic YAG fibers for high-energy laser (HEL) applications

    Lee, HeeDong; Keller, Kristin; Sirn, Brian


    There is a critical demand for high quality, transparent ceramic YAG fibers for high powered fiber lasers. The production of laser quality ceramic fibers hinges on advanced ceramic processing technology, along with the availability of highly sinterable powder with high phase and chemical purity. These two fundamental technologies have been successfully developed at UES. Nd (1.1 a/o) and Yb (1.0 a/o)-doped yttrium aluminum garnet (YAG) fibers with high optical quality were produced by combining UES's tailored powders with advanced consolidation processes including fiber extrusion and vacuum sintering. The as-sintered and as-annealed fibers, approximately 30 microns in diameter, appeared transparent and successfully transmitted laser beams; further development will allow for the production of doped ceramic YAG fiber lasers for advanced high power and high energy fiber laser systems.

  18. Laser brackets debonding: Tm:YAP, Nd:YAG, and GaAs diode lasers evaluation

    Dostálová, Tat'jana; Jelínková, Helena; Šulc, Jan; Koranda, Petr; Němec, Michal; Ivanov, Ilja; Miyagi, Mitsunobu; Iwai, Katsumasa


    The study demonstrates the possibility of using laser radiation for the ceramic bracket removing. Three laser radiations were examined for this effect and the removing possibility and velocity together with enamel and root damage were investigated. A diode pumped Tm:YAP microchip laser generating a wavelength 1.9 μm, diode pumped Nd:YAG laser with 1.44 μm wavelength, GaAs diode with 0.808 μm were used for the debonding purpose. The measurement of transmission and absorption of the basic element - bracket, adhesive resin, and enamel was also made with the goal to explain the source of the heat and bracket debonding. The explanation of the debonding effect is also presented. From the results it is possible to conclude that continuously running diode pumped microchip Tm:YAP laser having output power 1W can be a good candidate for ceramic bracket debonding procedure.

  19. 885-nm Pumped Ceramic Nd:YAG Master Oscillator Power Amplifier Laser System

    Yu, Anthony


    The performance of a traditional diode pumped solid-state laser that is typically pumped with 808-nm laser diode array (LDA) and crystalline Nd:YAG was improved by using 885-nm LDAs and ceramic Nd:YAG. The advantage is lower quantum defect, which will improve the thermal loading on laser gain medium, resulting in a higher-performance laser. The use of ceramic Nd:YAG allows a higher Nd dopant level that will make up the lower absorption at the 885-nm wavelength on Nd:YAG. When compared to traditional 808-nm pump, 885-nm diodes will have 30% less thermal load (or wasted heat) and will thus see a similar percentage improvement in the overall laser efficiency. In order to provide a more efficient laser system for future flight missions that require the use of low-repetition- rate (systems are numerous. The epitaxial structures of these 885-nm diodes are aluminum-free. There is a significant reduction in the thermal load generated from the Stokes shift or quantum defects. A Stokes shift is the energetic difference between the pump and laser photons. Pumping at a wavelength band closer to the lasing wavelength can reduce the thermal load by .30% compared to traditional pumping at 808 nm, and increase the optical- to-optical efficiency by the same factor. The slope efficiency is expected to increase with a reduction in the thermal load. The typical crystalline Nd:YAG can be difficult to produce with doping level >1% Nd. To make certain that the absorption at 885 nm is on the same par as the 808-nm diode, the Nd:YAG material needs to be doped with higher concentration of Nd. Ceramic Nd:YAG is the only material that can be tailored to specific needs.

  20. Morphologic assessment of dental surface/ glass ionomer cement interface: influence of Er:YAG laser pretreatment

    Silmara Aparecida Milori Corona


    Full Text Available Introduction and objective: The aim of this study was to assess the surface and the substrate/glass ionomer cement (GIC interface after Er:YAG laser irradiation by means of scanning electron microcopy. Material and methods: Thirty human third molars were selected and had their roots removed. Crowns were sectioned to obtain discs that were randomly assigned to three groups according to the surface pretreatment: 40% polyacrylic acid (control; Er:YAG laser irradiation (80mJ/2Hz or Er:YAG laser followed by 40% polyacrylic acid. Two discs of each group were put aside to the surface analysis and the others were bisected. One half received Ketac-Fil and the other received Fuji II LC. Specimens were prepared for SEM and were analyzed under different magnifications. Results: Er:YAG laser group showed no adhesive interface for both enamel and dentin, but strongly damaged the interface build-up for dentin/Fuji II LC. The application of laser irradiation followed by the polyacrylic acid exhibited gaps and irregularities for both substrates. Conclusion: Er:YAG laser irradiation combined or not with 40% polyacrylic acid produced a surface unfavorable for GIC interaction, especially for the resin-modified ones.

  1. Pulsed dye laser versus Nd:YAG laser in the treatment of plantar warts: a comparative study.

    El-Mohamady, Abd El-Shakor; Mearag, Ibrahim; El-Khalawany, Mohamed; Elshahed, Ahmed; Shokeir, Hisham; Mahmoud, Anas


    Plantar warts are common viral infection that are usually challenging in treatment. Conventional treatment methods are usually invasive, have low efficacy, and need long recovery periods. In this study, we compared pulsed dye laser (PDL) and neodymium yttrium aluminum garnet (Nd:YAG) lasers in the treatment of recalcitrant plantar warts. The study included 46 patients with multiple plantar warts. In each patient, lesions were divided into two groups: one treated with Nd:YAG (spot size, 7 mm; energy, 100 J/cm(2); and pulse duration, 20 ms) and the other with PDL (spot size, 7 mm; energy, 8 J/cm(2); and pulse duration, 0.5 ms). Laser sessions were applied every 2 weeks with maximum of six sessions. The study included 63% males and 37% females with a mean age of 29.6 ± 7.34 years. The cure rate was 73.9% with PDL with no significant difference (p = 0.87) from Nd:YAG (78.3%). The number of sessions required was more in PDL (mean, 5.05 ± 0.2) compared with Nd:YAG (mean, 4.65 ± 0.5) but without significant difference. Complications were significantly higher with Nd:YAG (43.5%) compared with PDL (8.7%). Hematoma was the most common complication recorded by Nd:YAG (28.3 %), and it was significantly higher (p = 0.002) than PDL (2.2%). Relapse was recorded in 8.7% with Nd:YAG compared with 13% in PDL with no significant difference (p = 0.74). Our results suggested that PDL and Nd:YAG lasers are effective in the treatment of resistant plantar warts. PDL is safer and less painful but needs more sessions, while Nd:YAG is more painful and shows more complications.

  2. Monostatic Doppler lidar using an Nd:YAG laser for wind-velocity measurement

    Bersenev, V. I.; Kaptsov, L. N.; Priezzhev, A. V.


    A monostatic Doppler lidar using a CW Nd:YAG laser has been developed for measurements of wind velocity. A series of atmospheric measurements using this lidar was carried out. At medium turbulence levels, the limiting lidar range is 200 m. As compared with a CO2 Doppler lidar, the Nd:YAG lidar has a better spatial resolution, is more convenient to use, and does not require a cooled photodetector.

  3. Selective photothermal ablation of tissue with a fiber-delivered Er:YAG laser

    Pierce, Mark C.; Dickinson, Mark R.; Devlin, Hugh


    The feasibility of using laser-induced photoemission signals to distinguish between hard and soft biological tissues during photothermal ablation with a pulsed Er:YAG laser has been investigated. Time-resolved emission spectroscopy indicated a threshold fluence of approximately 35 J/cm2 to regularly initiate photoemission from dental enamel, while no emission was detected from porcine muscle tissue with incident laser fluences of up to approximately 140 J/cm2. The delay time of an emission signal with respect to the incident, ablative Er:YAG laser pulse was found to decrease from approximately 150 microseconds near the emission threshold fluence to approximately 60 microseconds at the highest fluence level used. Optical multichannel analyzer spectroscopy of Er:YAG irradiated enamel demonstrated that photoemissions typically consisted of a broad, continuous background in the visible region, with superimposed peaks arising from the presence of elements including calcium, characteristic of plasma emission either from the sample surface or emission plume.

  4. In vitro application of optical transmission systems in erbium:YAG laser temporomandibular joint surgery

    Nuebler-Moritz, Michael; Hering, Peter; Niederdellmann, Herbert; Deuerling, Christian; Dammer, Ralf


    The experimental setup of this study is focused on the changes in temporomandibular joint tissue after irradiation with an Erbium:YAG laser. Initially, the free-running beam from the laser was focused onto freshly excised porcine tissue samples, indicating an optimum average energy density and pulse duration for the purpose of temporomandibular joint surgery of about 15 - 60 J/cm2 and 120 microsecond(s) - 240 microsecond(s) , respectively. Consecutively, an attempt was made to couple the Erbium:YAG laser beam on the one hand to optical fibers made of infrared-transmitting glasses (fluoride- and chalcogenide-based), on the other hand to a recently developed sapphire and liquid core fiber, respectively. From the preliminary observations of this investigation it appears that both the liquid core and the sapphire fiber are the most promising candidates for delivery of Erbium-YAG laser radiation in arthroscopic surgery of the craniomandibular articulation.

  5. Shear bond strength after Er:YAG laser radiation conditioning of enamel and dentin

    Dostalova, Tatjana; Jelinkova, Helena; Dolezalova, Libuse; Kubelka, Jiri; Prochazka, Stanislav; Hamal, Karel; Krejsa, Otakar


    This study compares bond shear strength between hard dental tissues and composite resin filling material after a classical acid etching treatment procedure and Er:YAG laser surface conditioning. The retention of composite resin was evaluated for three cases: (1) the flat dental substrate without any conditioning, (2) the classical drilling machine prepared surface with acid etching and (3) the Er:YAG laser conditioning of enamel and dentin. None significant differences between bond shear strength of the classical drilling machine prepared surface with acid etching in comparison with the laser radiation conditioning were found.

  6. Mode size and time duration fluctuations in a picosecond Nd:YAG laser

    Cutolo, A.; Zeni, L.; Berardi, V.; Bruzzese, R.; Solimeno, S.; Spinelli, N.


    A new technique is successfully used to analyze in real time the pulse-to-pulse fluctuations of mode size and time duration in a picosecond Nd:YAG laser. In particular we show that the pulse length (30 psec) of our active--passive mode-locked Nd:YAG laser is stable to within 10% when the cavity is perfectly tuned and the saturable absorber is fresh. This technique is experimentally shown to be effective and reliable for real-time analysis of the stability of ultrashort laser pulses under a broad range of experimental conditions.

  7. Comparison of Nd:YAG Ceramic Laser Pumped at 885 nm and 808 nm

    ZONG Nan; ZHANG Xiao-Fu; MA Qing-Lei; WANG Bao-Shan; CUI Da-Fu; PENG Qin-Jun; XU Zu-Yan; PAN Yu-Bai; FENG Xi-Qi


    Laser performance of 1064 nm domestic Nd: YA G ceramic lasers for 885 nm direct pumping and 808 nm traditional pumping are compared. Higher slope efficiency of 34% and maximum output power of 16.5 W are obtained for the 885nm pump with a 6ram length 1 at% Nd:YAG ceramic. The advantages for 885nm direct pumping are discussed in detail. This pumping scheme for highly doping a Nd:YAG ceramic laser is considered as an available way to generate high power and good beam quality simultaneously.

  8. Partially end-pumped Nd:YAG slab laser with a hybrid resonator.

    Du, K; Wu, N; Xu, J; Giesekus, J; Loosen, P; Poprawe, R


    A Nd:YAG slab is partially end pumped by a diode laser stack with three diode laser bars. The pumped volume has a rectangular cross section. A hybrid resonator, which is stable in the plane of small dimension and is off-axis unstable in the plane of large dimension of the gain cross section, was used to yield highly efficient laser operation at diffraction-limited beam quality. The laser design and experimental results are reported.

  9. Physical and optical limitations using ArF-excimer and Er:YAG lasers for PRK

    Semchishen, Vladimir A.; Mrochen, Michael; Seiler, Theo


    The Erbium:YAG laser emitting at a wavelength of 2,94 micrometer have been promised as an alternative laser for the ArF-excimer laser (193 nm) in photorefractive keratectomy (PRK). This report discusses the limitations of laser parameters such as wavelength, energy density and pulse duration for the ablation of the cornea. In addition, the melting process during ablation on the corneal surface roughness may play a role.

  10. [Effects of Nd: YAG laser irradiation on the root surfaces and adhesion of Streptococcus mutans].

    Yuanhong, Li; Zhongcheng, Li; Mengqi, Luo; Daonan, Shen; Shu, Zhang; Shu, Meng


    This study aimed to evaluate the effects of treatment with different powers of Nd: YAG laser irradiation on root surfaces and Streptococcus mutans (S. mutans) adhesion. Extracted teeth because of severe periodontal disease were divided into the following four groups: control group, laser group 1, laser group 2, and laser group 3. After scaling and root planning, laser group 1, laser group 2, and laser group 3 were separately treated with Nd: YAG laser irradiation (4/6/8 W, 60 s); however, the control group did not receive the treatment. Scanning electron microscopy (SEM) was used to determine the morphology. S. mutans were cultured with root slices from each group. Colony forming unit per mL (CFU·mL⁻¹) was used to count and compare the amounts of bacteria adhesion among groups. SEM was used to observe the difference of bacteria adhesion to root surfaces between control group (scaling) and laser group 2 (6 W, 60 s), thereby indicating the different bacteria adhesions because of different treatments. Morphology alterations indicated that root surfaces in control group contain obvious smear layer, debris, and biofilm; whereas the root surfaces in laser group contain more cracks with less smear layer and debris. The bacteria counting indicated that S. mutans adhesion to laser group was weaker than that of control group (P0.05) was observed. Morphology alterations also verified that S. mutans adhesion to laser group 2 (6 W, 60 s) was weaker than that of control group (scaling). This study demonstrated that Nd: YAG laser irradiation treatment after scaling can reduce smear layer, debris, and biofilm on the root surfaces as compared with conventional scaling. The laser treatment reduces the adhesion of S. mutans as well. However, Nd: YAG laser irradiation can cause cracks on the root surfaces. In this experiment, the optimum laser power of 6 W can thoroughly remove the smear layer and debris, as well as relatively improve the control of thermal damagee.

  11. Emission spectra of YAG:Er3+ under pulse laser-thermal excitation

    Marchenko, V. M.; Shakir, Yu. A.


    Spectra and kinetics of emission of YAG:0.5% Er3+ monocrystal in visible and NIR ranges were investigated under laser-thermal excitation by the pulses of CO2 laser of 100 ns duration at wavelength λ = 10,6 μμm. Kinetics of integral emission was interpreted.

  12. 407 W End-pumped Multi-segmented Nd:YAG Laser.

    Kracht, Dietmar; Wilhelm, Ralf; Frede, Maik; Dupré, Klaus; Ackermann, Lothar


    A composite crystalline Nd:YAG rod consisting of 5 segments with different dopant concentrations for high power diode end-pumping is presented. A maximum laser output power of 407 W with an optical-to-optical efficiency of 54 % was achieved by longitudinal pumping with a high power laser diode stack.

  13. Nd:YAG solid-state ring laser pumped by a light-emitting diode

    Belozerov, S.A.; Kornienko, L.S.; Kravtsov, N.V.; Kuratev, I.I.; Rusakov, S.I.; Stel' makh, M.F.; Shelaev, A.A.; Shelaev, A.I.


    This letter reports lasing in an Nd:YAG solid-state laser (lambda = 1.06 pumped either in pulses or continuously by a light-emitting diode. We report the first experimental results on this laser.(AIP)

  14. Nd-YAG laser treatment in a patient with complicated pilonidal cysts

    Lindholt, Christine S; Lindholt, Jes S.; Lindholt, Jan


    suppurative cases. The effect could be attributable to the ability of the YAG laser to operate at a wavelength of 1064 nm and to penetrate the skin to levels deeper than that of most other lasers before the energy is absorbed in melanin and oxyhaemoglobin. Consequently, the contents of the cyst can be reached...

  15. High-efficiency diode-pumped femtosecond Yb:YAG ceramic laser

    Zhou, Binbin; Wei, Z.Y.; Zou, Y.W.


    A highly efficient diode-end-pumped femtosecond Yb:yttrium aluminum garnet (YAG) ceramic laser was demonstrated. Pumped by a 968 nm fiber-coupled diode laser, 1.9 W mode-locked output power at a repetition rate of 64.27 MHz was obtained with 3.5 W absorbed pump power, corresponding to a slope...

  16. The Construction of a Nd:YAG Laser and Observation of the Output.


    Osternik, L. M., Thermal Effects in a Nd:YAG Laser, J. Appl. Phys. 41,-6-1 . 18. Koechner, W., p. 353. 19. Svelto , 0., Principles of Lasers, p. 152...Plenum Press, New York and London, 1982. 20. Svelto , 0., p. 154. A;6 -9 ;:..: .-,-. .- - - .- . • - -- . . . . . . . . . .. .. . . . . . .. . 9.’’, a

  17. Comparison of preparation speed of Er:YAG laser and conventional drilling machine

    Jelinkova, Helena; Dostalova, Tatjana; Dolezalova, Libuse; Krejsa, Otakar; Hamal, Karel; Kubelka, Jiri; Prochazka, Stanislav


    Clinical tests of the caries treatment with a Er:YAG laser system have been very promising. The problem of the Er:YAG laser drilling machine is the speed of preparation. It is not possible to increase the laser energy and repetition rate because this process is directly connected with temperature elevation. Therefore attention has been paid to define the differences between the classical and the laser drilling effect with a safe but effective laser energy and repetition rate. For the experiment, an Er:YAG laser drilling machine with an articulated arm was designed. Thirty samples of extracted human teeth were cut by both this system and classical drilling machine. The circumference, area and structure of surface sections were observed and analyzed. From the comparison of the measured time of preparation significant differences followed from the time of preparation. The time of preparation related to 1 mm2 of the cut surface was 5.42 sec for the Er:YAG laser machine and 0.66 sec for the classical method. From this comparison it follows that the laser system is 8 times slower than the classical preparation technique. In both cases the roughness of the surface analyzed by SCAN was found similar. Also, there were no differences between the distribution of the elements, especially calcium and phosphorus.

  18. Nd : YAG surgical laser effects in canine prostate tissue: temperature and damage distribution

    van Nimwegen, S. A.; L'Eplattenier, H. F.; Rem, A. I.; van der Lugt, J. J.; Kirpensteijn, J.


    An in vitro model was used to predict short-term, laser-induced, thermal damage in canine prostate tissue. Canine prostate tissue samples were equipped with thermocouple probes to measure tissue temperature at 3, 6, 9 and 12 mm depths. The tissue surface was irradiated with a Nd:YAG laser in contact

  19. The effect of a pulsed Nd:YAG laser in non-surgical periodontal therapy

    Slot, D.E.; Kranendonk, A.A.; Paraskevas, S.; van der Weijden, F.


    Background: Laser treatment may serve as an alternative or adjunctive treatment to conventional mechanical therapy in periodontics. The neodymium-doped:yttrium, aluminum, and garnet (Nd:YAG) laser has been used in periodontics. Systematic reviews aid in clinical decision-making. The aim of this stud

  20. Chemical Changes Associated with Increased Acid Resistance of Er:YAG Laser Irradiated Enamel

    Jennifer Manuela Díaz-Monroy


    Full Text Available Background. An increase in the acid resistance of dental enamel, as well as morphological and structural changes produced by Er:YAG laser irradiation, has been reported. Purpose. To evaluate the chemical changes associated with acid resistance of enamel treated with Er:YAG laser. Methods. Forty-eight enamel samples were divided into 4 groups (n=12. Group I (control; Groups II, III, and IV were irradiated with Er:YAG at 100 mJ (12.7 J/cm2, 200 mJ (25.5 J/cm2, and 300 mJ (38.2 J/cm2, respectively. Results. There were significant differences in composition of irradiated groups (with the exception of chlorine and in the amount of calcium released. Conclusions. Chemical changes associated with an increase in acid resistance of enamel treated with Er:YAG laser showed a clear postirradiation pattern characterized by a decrease in C at.% and an increase in O, P, and Ca at.% and no changes in Cl at.%. An increased Ca/P ratio after Er:YAG laser irradiation was associated with the use of higher laser energy densities. Chemical changes produced by acid dissolution showed a similar trend among experimental groups. Stable or increased Ca/P ratio after acid dissolution was observed in the irradiated groups, with reduction of Ca released into the acid solution.

  1. Nd:YAG laser therapy for rectal and vaginal venous malformations.

    Gurien, Lori A; Jackson, Richard J; Kiser, Michelle M; Richter, Gresham T


    Limited therapeutic options exist for rectal and vaginal venous malformations (VM). We describe our center's experience using Nd:YAG laser for targeted ablation of abnormal veins to treat mucosally involved pelvic VM. Records of patients undergoing non-contact Nd:YAG laser therapy of pelvic VM at a tertiary children's hospital were reviewed. Symptoms, operative findings and details, complications, and outcomes were evaluated. Nine patients (age 0-24) underwent Nd:YAG laser therapy of rectal and/or vaginal VM. Rectal bleeding was present in all patients and vaginal bleeding in all females (n = 5). 5/7 patients had extensive pelvic involvement on MRI. Typical settings were 30 (rectum) and 20-25 W (vagina), with 0.5-1.0 s pulse duration. Patients underwent the same-day discharge. Treatment intervals ranged from 14 to 180 (average = 56) weeks, with 6.1-year mean follow-up. Five patients experienced symptom relief with a single treatment. Serial treatments managed recurrent bleeding successfully in all patients, with complete resolution of vaginal lesions in 40% of cases. No complications occurred. Nd:YAG laser treatment of rectal and vaginal VM results in substantial improvement and symptom control, with low complication risk. Given the high morbidity of surgical resection, Nd:YAG laser treatment of pelvic VM should be considered as first line therapy.

  2. In vitro study of the variable square pulse Er:YAG laser cutting efficacy for apicectomy.

    Grgurević, Josko; Grgurević, Lovro; Miletić, Ivana; Karlović, Zoran; Krmek, Silvana Jukić; Anić, Ivica


    Variable square pulse (VSP) Er:YAG laser should be quicker than older Er:YAG lasers. The objectives were: (1) comparison of VSP laser and mechanical handpiece efficacy for apicectomy and (2) determination of optimal pulse width/energy/frequency combination. Sixty extracted, single-rooted mature human teeth with round apical parts were instrumented, root filled, cleaned, and divided into four groups. Apical 2 mm of each root were apicectomized with mechanical handpiece and Er:YAG laser with three different settings (LaserA = 200 mJ/300 microseconds/ 8 Hz; LaserB = 200 mJ/100 microseconds/8 Hz; LaserC = 380 mJ/100 microseconds/20 Hz). Timing results were statistically compared. LaserC was the most efficient setting. Differences between groups were significant except between LaserC-Mechanical and LaserA-LaserC (P apicectomy is slower by a factor of 7-31 than mechanical handpiece, but treatment outcome is acceptable. Optimal settings for apicectomy with VSP laser are 380 mJ/100 microseconds/20 Hz. Copyright 2005 Wiley-Liss, Inc.

  3. Thomson scattering from near-solid density plasmas using soft x-ray free electron lasers

    Höll, A


    We propose a collective Thomson scattering experiment at the VUV free electron laser facility at DESY (FLASH) which aims to diagnose warm dense matter at near-solid density. The plasma region of interest marks the transition from an ideal plasma to a correlated and degenerate many-particle system and is of current interest, e.g. in ICF experiments or laboratory astrophysics. Plasma diagnostic of such plasmas is a longstanding issue. The collective electron plasma mode (plasmon) is revealed in a pump-probe scattering experiment using the high-brilliant radiation to probe the plasma. The distinctive scattering features allow to infer basic plasma properties. For plasmas in thermal equilibrium the electron density and temperature is determined from scattering off the plasmon mode.

  4. Thomson scattering from near-solid density plasmas using soft x-ray free electron lasers

    Holl, A; Bornath, T; Cao, L; Doppner, T; Dusterer, S; Forster, E; Fortmann, C; Glenzer, S H; Gregori, G; Laarmann, T; Meiwes-Broer, K H; Przystawik, A; Radcliffe, P; Redmer, R; Reinholz, H; Ropke, G; Thiele, R; Tiggesbaumker, J; Toleikis, S; Truong, N X; Tschentscher, T; Uschmann, I; Zastrau, U


    We propose a collective Thomson scattering experiment at the VUV free electron laser facility at DESY (FLASH) which aims to diagnose warm dense matter at near-solid density. The plasma region of interest marks the transition from an ideal plasma to a correlated and degenerate many-particle system and is of current interest, e.g. in ICF experiments or laboratory astrophysics. Plasma diagnostic of such plasmas is a longstanding issue. The collective electron plasma mode (plasmon) is revealed in a pump-probe scattering experiment using the high-brilliant radiation to probe the plasma. The distinctive scattering features allow to infer basic plasma properties. For plasmas in thermal equilibrium the electron density and temperature is determined from scattering off the plasmon mode.

  5. SEM evaluation of the morphological changes in hard dental tissues prepared by Er: YAG laser and rotary instruments

    Tomov Georgi


    Full Text Available Effective ablation of dental hard tissues by means of the erbium:yttrium-aluminum garnet (Er: YAG laser has been reported recently, and its application to caries removal and cavity preparation has been expected. However, few studies have investigated the morphological changes in hard dental tissues after Er: YAG laser caries treatment. In the present study the morphological changes in hard dental tissues after Er: YAG laser caries ablation in vitro was compared with that of conventional mechanical treatment. Thirty extracted human teeth with caries were used. Ten tooth was treated with the Er: YAG laser, and the other was treated with a conventional steel and diamond burs. Laser treatment was performed by means of a non-contact irradiation modes with cooling water spray, with a new Er: YAG laser (LiteTouch. Conventional bur treatment was conducted by means of a low-speed micromotor and air turbine with water cooling. Scanning electron microscope (SEM observations were performed for each treatment. The Er: YAG laser ablated carious dentin effectively with minimal thermal damage to the surrounding intact dentin, and removed infected and softened carious dentin to the same degree as the burtreatment. In addition, a lower degree of vibration was noted with the Er: YAG laser treatment. The SEM examination revealed characteristic micro-irregularities of the lased dentin and enamel surfaces with potential benefits for adhesive restorations. Our results show that the Er: YAG laser is promising as a new technical modality for caries treatment

  6. Welding of Thermomechanically Rolled Steel by Yb:YAG Disk Laser / Spawanie Stali Walcowanej Termomechanicznie Laserem Dyskowym Yb:YAG

    Lisiecki A.


    Full Text Available Autogenous laser welding of 5.0 mm thick butt joints of thermomechanically rolled steel S700MC was investigated. The Yb:YAG disk laser TruDisk 3302 emitted at 1.03 μm was used for the trials of autogenous welding. The effect of laser welding parameters and thus thermal conditions of welding on weld shape, microstructure of weld metal and heat affected zone (HAZ, tensile strength, bending angle, impact toughness and microhardness profile was determined. Studies have shown that it is advantageous to provide a high welding speed and low heat input. High cooling rate of weld metal and HAZ leads to the formation of a favorable structure characterized by a large proportion of fine-grained acicular ferrite and provides high mechanical properties of butt joints.

  7. Laser lithotripsy with the Ho:YAG laser: fragmentation process revealed by time-resolved imaging

    Schmidlin, Franz R.; Beghuin, Didier; Delacretaz, Guy P.; Venzi, Giordano; Jichlinski, Patrice; Rink, Klaus; Leisinger, Hans-Juerg; Graber, Peter


    Improvements of endoscopic techniques have renewed the interest of urologists in laser lithotripsy in recent years. Laser energy can be easily transmitted through flexible fibers thereby enabling different surgical procedures such as cutting, coagulating and lithotripsy. The Ho:YAG laser offers multiple medical applications in Urology, among them stone fragmentation. However, the present knowledge of its fragmentation mechanism is incomplete. The objective was therefore to analyze the fragmentation process and to discuss the clinical implications related to the underlying fragmentation mechanism. The stone fragmentation process during Ho:YAG laser lithotripsy was observed by time resolved flash video imaging. Possible acoustic transient occurrence was simultaneously monitored with a PVDF-needle hydrophone. Fragmentation was performed on artificial and cystine kidney stones in water. We observed that though the fragmentation process is accompanied with the formation of a cavitation bubble, cavitation has only a minimal effect on stone fragmentation. Fragment ejection is mainly due to direct laser stone heating leading to vaporization of organic stone constituents and interstitial water. The minimal effect of the cavitation bubble is confirmed by acoustic transients measurements, which reveal weak pressure transients. Stone fragmentation with the Holmium laser is the result of vaporization of interstitial (stone) water and organic stone constituents. It is not due to the acoustic effects of a cavitation bubble or plasma formation. The fragmentation process is strongly related with heat production thereby harboring the risk of undesired thermal damage. Therefore, a solid comprehension of the fragmentation process is needed when using the different clinically available laser types of lithotripsy.

  8. [Retinal photocoagulation with a pulsed, frequency-doubled Nd:YAG laser (532 nm)].

    Roider, J; Schiller, M; el Hifnawi, E S; Birngruber, R


    The small difference in wavelength between an argon laser (514 nm) and a frequency-doubled Nd:YAG laser (532 nm), together with the advantage of the solid-state technology, makes the Nd:YAG laser likely to play a major role in retinal photocoagulation in the near future. For technical reasons all frequency-doubled Nd:YAG lasers work in a quasi-continuous mode, emitting a burst of highly repetitive short laser pulses during the exposure time desired. We investigated the side effects due to high peak irradiances of those short laser pulse trains (Crystal Focus Nd:YAG laser, Emerald; pulse duration 1-10 microseconds, repetition rate 13 KHz) in rabbits in comparison with a standard argon laser system (Zeiss, Visulas, Argon II). The energy necessary for blanching the retina was similar in both cases. As opposed to the argon laser system, subretinal bubbles were regularly visible ophthalmoscopically with the Nd:YAG system, when average powers as high as 200 mW were used. The ED50 power for bubble formation is about 2-3 times above the ED50 power for blanching. Thermal calculations show that this bubble formation effect is likely to be related to the peak power of the short pulses. The hemorrhage threshold is similar in both systems. However, light microscopically there is no difference between the two laser systems. Panretinal photocoagulation (300-500 microns, 100-200 ms) in patients with proliferative diabetic retinopathy produced such bubbles about once per 1000 lesions.

  9. Implant Surface Temperature Changes during Er:YAG Laser Irradiation with Different Cooling Systems.

    Abbas Monzavi


    Full Text Available Peri-implantitis is one of the most common reasons for implant failure. Decontamination of infected implant surfaces can be achieved effectively by laser irradiation; although the associated thermal rise may cause irreversible bone damage and lead to implant loss. Temperature increments of over 10ºC during laser application may suffice for irreversible bone damage.The purpose of this study was to evaluate the temperature increment of implant surface during Er:YAG laser irradiation with different cooling systems.Three implants were placed in a resected block of sheep mandible and irradiated with Er:YAG laser with 3 different cooling systems namely water and air spray, air spray alone and no water or air spray. Temperature changes of the implant surface were monitored during laser irradiation with a K-type thermocouple at the apical area of the fixture.In all 3 groups, the maximum temperature rise was lower than 10°C. Temperature changes were significantly different with different cooling systems used (P<0.001.Based on the results, no thermal damage was observed during implant surface decontamination by Er:YAG laser with and without refrigeration. Thus, Er:YAG laser irradiation can be a safe method for treatment of periimplantitis.

  10. Removal effects of the Nd:YAG laser and Carisolv on carious dentin.

    Yamada, Y; Hossain, M; Kawanaka, T; Kinoshita, J; Matsumoto, K


    The purpose of this study was to investigate the removal effect of the Nd:YAG laser irradiation and Carisolv on carious dentin. Many previous studies have reported several simple and alternative techniques, such as lasers and chemicals, for caries removal. Carisolv was applied on the surface of 20 extracted human anterior and molar teeth for 1 min and then the Nd:YAG laser was irradiated with a continuous water spray for another 1 min. The energy densities were varied from 2 to 6W with a repetition rate of 20 pps. As caries removal progressed, the cavity was carefully assessed by DIAGNOdent. Each lesion was photographed before and after treatment, and the treated cavity was observed microscopically using a stereoscope and with scanning electron microscope (SEM). Thermal change at the time of laser irradiation was measured by thermovision. Our results revealed that application of Carisolv followed by Nd:YAG laser irradiation at 4-6W pulse energy effectively removed dentin caries. The total procedure was usually repeated once or twice for complete caries removal. From the SEM study, it was found that the cavity surface treated with the laser revealed various patterns of microirregularity, often accompanied by microfissure propagation. There was also no smear layer. It was revealed that Nd:YAG laser and Carisolv could provide an alternative technique for caries removal instead of the conventional mechanical drilling and cutting.

  11. Effect of Er:YAG laser on dentin bonding durability under simulated pulpal pressure.

    Bakry, Ahmed Samir; Nakajima, Masatoshi; Otsuki, Masayuki; Tagami, Junji


    To evaluate the effects of Er:YAG laser ablation on the microtensile bond strength and the nanoleakage of Er:YAG-lased dentin bonded to a self-etching adhesive system with and without pulpal pressure. Twenty flat dentin surfaces were obtained from extracted molars. Ten specimens were irradiated by Er:YAG laser, other specimens (control group) were ground using #600 SiC paper. Direct communication to the pulp chamber was created by cutting at a level approximately 1 mm below the cementoenamel junction and parallel to the occlusal surface. The experimental groups were exposed to a simulated pulpal pressure of 15 cm H2O. Each specimen was restored using an adhesive and a photocured composite. The specimens were then sectioned vertically to obtain dentin/adhesive slabs. Ninety-six slabs were prepared for microtensile bond testing. Sixty-four slabs were immersed in ammoniacal silver nitrate tracer solution for 18 h, then rinsed thoroughly, and immersed in photodeveloping solution for 6 h prior to their examination by FE-SEM. The method of dentin preparation and the pulpal pressure storage condition significantly affected the microTBS, while the storage duration did not (p < 0.05). The nanoleakage patterns observed in the dentin/bond interface differed depending on whether the dentin was conventionally prepared or ablated by Er:YAG laser. Er:YAG laser ablation to dentin adversely affected the microTBS and the sealing ability of SE Bond bonded to dentin under simulated pulpal condition.

  12. Treatment of gingival hyperpigmentation for esthetic purposes by Nd:YAG laser: report of 4 cases.

    Atsawasuwan, P; Greethong, K; Nimmanon, V


    Gingival hyperpigmentation may cause esthetic problems and embarrassment, especially in patients with a gummy smile. This report presents the use of the Nd:YAG laser for gingival depigmentation. Four cases, 3 females and 1 male, ages between 24 to 28 years old, presented with the same chief complaint of unesthetic gingiva caused by melanin hyperpigmentation. The Nd:YAG laser was set at 6 watts, 60 millijoules per pulse, and 100 pulses per second. The procedures were performed with contact mode in all pigmented areas by using a handpiece with a 320 microm diameter fiber optic. Ablation of the gingival hyperpigmented areas were accomplished without any bleeding complications or significant postoperative pain. Three to 4 weeks after the procedures, the hyperpigmented gingiva appeared healthy, pink, and firm. No recurrence of hyperpigmentation had been found in 11 to 13 months of follow-up. However, in delicate areas such as the marginal gingiva, the Nd:YAG laser should be used cautiously.

  13. Resistance of YAG:Nd sup 3+ laser frequency converters to ionizing radiation

    Zakharkin, B. I.; Kulevskiy, L. A.; Nikolayev, V. N.; Toropkin, G. N.


    This study presents a review of published work on the radiation resistance of YAG:Nd sup 3+ laser frequency converters, and describes the results of experiments on the influence of gamma-irradiation of nonlinear crystals on the output characteristics of YAG:Nd sup 3+ lasers with second-harmonic generation inside or outside the cavity. The influence of radiation on the optical properties of nonlinear crystals is investigated. It is found that radiation degrades the generation of optical harmonics in YAG:ND sup 3+ lasers employing nonlinear elements made of SDA, DSDA, LiIO3 and DKDR crystals, starting at doses of 10 to the 5th power - 10 to the 6th power rad. Deuterized nonlinear crystals are found to be more resistant to ionizing radiation.

  14. Effects of Er:YAG Laser on Mineral Content of Sound Dentin in Primary Teeth


    The aim of the present study was to evaluate the mineral content of sound dentin in primary teeth prepared using an Er:YAG laser at two different power settings. Thirty-six primary second molars were used in this study. Three dentin slabs were obtained from each tooth, and the slabs were randomly divided into three groups: Group A, control; Group B, Er:YAG laser at 3.5 W, 175 mJ, and 20 Hz, short pulse mode; and Group C, Er:YAG laser at 4 W, 200 mJ, and 20 Hz, medium-short pulse mode. One den...

  15. Nd:YAG laser removal of pupillary membranes developed after ECCE with PC-IOL implantation.

    Kozobolis, V P; Pallikaris, I G; Tsambarlakis, I G; Vlachonikolis, I G


    To define the frequency of development of pupillary membranes after ECCE with PC-IOL implantation, and to remove the pupillary membranes using the Nd:YAG laser. From 400 patients who had undergone ECCE and were free from local or systemic illness affecting the blood-ocular barrier, 20 eyes developed pupillary membranes Nd:YAG laser was used to remove these pupillary membranes. The frequency of pupillary membranes was found to be 5% (9.8% in pex eyes and 3.3% to the non-pex eyes). Visual acuity improved in 17 eyes by 2 to 5 Snellen lines. No serious complications were observed, endothelium inclusive. Pseudoexfoliation might play a significant role in the development of postoperative pupillary membranes which could be successfully treated with the use of Nd:YAG laser. The safety of the procedure has to be evaluated in relation to the corneal endothelium damage in long-term.

  16. Er:YAG and CTH:YAG laser radiation: contact versus non-contact enamel ablation and sonic-activated bulk composite placement

    Buckova, M.; Kasparova, M.; Dostalova, T.; Jelinkova, H.; Sulc, J.; Nemec, M.; Fibrich, M.; Bradna, P.; Miyagi, M.


    Laser radiation can be used for effective caries removal and cavity preparation without significant thermal effects, collateral damage of tooth structure, or patient discomfort. The aim of this study was to compare the quality of tissue after contact or non-contact Er:YAG and CTH:YAG laser radiation ablation. The second goal was to increase the sealing ability of hard dental tissues using sonic-activated bulk filling material with change in viscosity during processing. The artificial caries was prepared in intact teeth to simulate a demineralized surface and then the Er:YAG or CTH:YAG laser radiation was applied. The enamel artificial caries was gently removed by the laser radiation and sonic-activated composite fillings were inserted. A stereomicroscope and then a scanning electron microscope were used to evaluate the enamel surface. Er:YAG contact mode ablation in enamel was quick and precise; the cavity was smooth with a keyhole shaped prism and rod relief arrangement without a smear layer. The sonic-activated filling material was consistently regularly distributed; no cracks or microleakage in the enamel were observed. CTH:YAG irradiation was able to clean but not ablate the enamel surface; in contact and also in non-contact mode there was evidence of melting and fusing of the enamel.

  17. Marginal microleakage in vitro study on class V cavities prepared with Er:YAG laser and etched with acid or etched with Er:YAG laser and acid; Estudo in vitro da microinfiltracao marginal em cavidades classe V preparadas com laser de Er:YAG e condicionadas com acido ou com laser de Er:YAG e acido

    Tavares, Henrique Dutra Simoes


    Microleakage at the interface between the teeth and the restorative materials remains a problem with composite resin restorations. Microleakage at the gingival margins of class V cavities restorations still challenge as they are usually placed in dentin and/or cementum. Previous studies have shown that the cavity preparation with Er:YAG laser is possible. It has been reported that Er:YAG laser has ability to create irregular surface providing micromechanical retention for adhesive dental restorative materials and to improve marginal sealing. The purpose of this in vitro study was to evaluate the marginal microleakage on class V cavities prepared with Er:YAG laser and etched with acid or with Er:YAG laser and acid, in compared to those prepared and etched conventionally. Thirty human molars were divided into three groups, namely: group I - prepared with Er:YAG laser (KaVo KEY Laser II - Germany) and etched with 37% phosphoric acid; group II - prepared with Er:YAG laser and etched with Er:YAG laser and 37% phosphoric acid; group III (control group) - prepared with high speed drill and etched with 37% phosphoric acid. All cavities were treated with same adhesive system (Single Bond - 3M) and restored with the composite resin (Z100 - 3M), according to the manufacturer's instructions. The specimens were stored at 37 deg C in water for 24 hours, polished with Sof-Lex discs (3M), thermally stressed, sealed with a nail polish coating except for the area of the restoration and 1 mm around it, and immersed in a 50% aqueous solution of silver nitrate for 24 hours. After that, the specimens were rinsed in water, soaked in a photodeveloping solution and exposed to a fluorescent light for 8 hours. The teeth were embedded in an autopolymerizing resin and sectioned longitudinally using a diamond saw microtome under running water. The sections were photographed. The microleakage at the occlusal cavity and at the gingival margins of each specimen was evaluated with scores (0

  18. Nd: YAG Laser-Pumped Raman-Shifted Methane Laser as an Eye-safe Laser Rangefmder

    Jai Paul Dudeja


    Full Text Available In this article, a feasibility study of the design and performance of a laser rangefinder emitting at an eye-safe wavelength of 1.54 micron, is reported. It is a Raman-shifted laser where an Nd:YAG laser emitting at a wavelength of 1.06 micron is used as pumping source that is incident on a Raman cell containing methane gas at a very high pressure, rsulting in the Stokes radiation at 1.54 micron. Conversion efficiencies as higb as 40 per cent have been reported so far by some workers and continued efforts are on to increase this value close tothe theoretical Qmits. A comparative performance of this laser, proposed as a futuristic military rangefinder, is studied vis-a-vis commonly used Nd:YAG lasers as well as more recent rangefinders using CO2 lasers. A comparison of this laser emitting at 1.54 micron,with Er : glass laser emitting at the same wavelength, is also discussed.

  19. Comparative study between Fortify and Nd:YAG laser used for marginal sealing in composite restorations

    Navarro, Ricardo S.; Esteves, Grazia V.; Oliveira, Wilson T., Jr.; Matos, Adriana B.; Turbino, Mirian L.; Youssef, Michel N.; Matson, Edmir


    The aim of this study was to evaluate microleakage of composite restorations submitted to marginal treatment. Class V preparations with walls located in enamel were performed at buccal and lingual surfaces of eighteen recently extracted, non-carious human premolars. Cavities were restored with composite resins and adhesive system. Samples were stored in distilled water for 48h and polished with Sof-Lex discs. Teeth were randomly divide in six groups: G1 - Control; G2 - marginal treatment with surface sealant; G3 - Nd:YAG 25 Hz, 80mJ, 2W; G4 - Nd:YAG 20Hz, 100mJ, 2W; G5 - Nd:YAG 30Hz, 60mJ, 1.8W; G6 - Nd:YAG 30Hz, 40mJ, 1.2W. Contact fiberoptic (300μm) pulsed (1.064 μm) Nd:YAG laser was used for 30sec, under air cooling. Teeth were impermeabilized, immersed in a dye (Rhodamine B) for 4h at 37°, and sectioned. Specimens were evaluated under light microscopy and evaluated with scores. Results were analyzed with Kruskal- Wallis test (p=0.05) and showed that there were significant differences between marginal treatments; there were no significant differences beaten groups 1, 2, 4 and 3, 5, 6; lower values of microleakage were at groups 3, 5, 6. Nd:YAG laser showed marginal sealing ability and decreased microleakage of composite resins restorations.

  20. Thomson Parabola Spectrometer for Energetic Ions Emitted from Sub-ns Laser Generated Plasmas

    Mariapompea Cutroneo


    Full Text Available Laser-generated plasmas were obtained in high vacuum by irradiating micrometric thin films (Au, Au/Mylar, Mylar with the Asterix laser at the PALS Research Infrastructure in Prague. Irradiations at the fundamental wavelength, 300 ps pulse duration, at intensities up to about 1016W/cm2, enabled ions to be accelerated in forward direction with kinetic energies of the order of 2 MeV/charge state. Protons above 2 MeV were obtained in the direction orthogonal to the target surface in selffocusing conditions. Gold ions up to about 120 MeV and 60+ charge state were detected. Ion collectors and semiconductor SiC detectors were employed in time-of-flight arrangement in order to measure the ion velocities as a function of the angle around the normal direction to the target surface. A Thomson parabola spectrometer (TPS with a multi-channel-plate detector was used to separate the different ion contributions to the charge emission in single laser shots, and to get information on the ion charge states, energy and proton acceleration. TPS experimental spectra were compared with accurate TOSCA simulations of TPS parabolas.

  1. Thomson scattering system on the TEXTOR tokamak using a multi-pass laser beam configuration

    Kantor, M Yu; Donne, A J H; Jaspers, R; Van der Meiden, H J [FOM-Institute for Plasma Physics Rijnhuizen , Association EURATOM-FOM, PO Box 1207, 3430 BE Nieuwegein (Netherlands)], E-mail:


    The main challenge for the Thomson scattering (TS) diagnostic on the TEXTOR tokamak is the detailed study of fast plasma events at a high spatial resolution and a high repetition rate of the measurements. The diagnostic uses intra-cavity probing of the plasma with a repetitively pulsed ruby laser and a fast CMOS camera as detectors. Since 2004, the TS system on TEXTOR has been gradually and systematically enhanced for the measurements of fast plasma events. For that it has recently been upgraded to obtain a multi-pass configuration. Two spherical mirrors have been installed that force the laser beam to probe the plasma a specified number of times before it is directed back into the laser medium. The diagnostics with the upgraded probing system have achieved the measurement accuracy of 3% for the electron temperature and 1.5% for the electron density at <1 cm spatial resolution and 3 x 10{sup 19} m{sup -3} plasma density and can measure at 5 kHz during an interval up to 8 ms. This makes it possible to detect, amongst others, fine structures of magnetic islands and variations of the edge pedestal in the ELMy limiter H-mode.

  2. Thomson scattering system on the TEXTOR tokamak using a multi-pass laser beam configuration

    Kantor, M Yu; Donné, A J H; Jaspers, R; van der Meiden, H J; TEXTOR Team


    The main challenge for the Thomson scattering (TS) diagnostic on the TEXTOR tokamak is the detailed study of fast plasma events at a high spatial resolution and a high repetition rate of the measurements. The diagnostic uses intra-cavity probing of the plasma with a repetitively pulsed ruby laser and a fast CMOS camera as detectors. Since 2004, the TS system on TEXTOR has been gradually and systematically enhanced for the measurements of fast plasma events. For that it has recently been upgraded to obtain a multi-pass configuration. Two spherical mirrors have been installed that force the laser beam to probe the plasma a specified number of times before it is directed back into the laser medium. The diagnostics with the upgraded probing system have achieved the measurement accuracy of 3% for the electron temperature and 1.5% for the electron density at <1 cm spatial resolution and 3 × 1019 m-3 plasma density and can measure at 5 kHz during an interval up to 8 ms. This makes it possible to detect, amongst others, fine structures of magnetic islands and variations of the edge pedestal in the ELMy limiter H-mode.

  3. Composite resin's adhesive resistance to dentin: influence of Er:YAG laser focal distance variation.

    Corona, Silmara Aparecida Milori; Atoui, Juliana Abdallah; Chimello, Daniela Thomazatti; Borsatto, Maria Cristina; Pecora, Jesus Djalma; Dibb, Regina Guenka Palma


    The aim of this study was to analyze in vitro the influence of Er:YAG laser focal distance variation on tensile bond strength of a composite resin to dentin. Although there are several studies using the Er:YAG laser for dentin treatment, there is a lack of available literature related to the Er:YAG laser focal distance variation. Sixty vestibular and lingual dentin surfaces from extracted human third molars, kept in a 0.4% azide sodium solution, were ground and assigned to six groups. The control group was conditioned with 35% phosphoric acid (CA). In the lased groups, the dentin surface treatment was performed by irradiation with Er:YAG laser (80 mJ/2 Hz), varying the focal distance (11, 12, 14, 16, and 17 mm), followed by acid etching. The Single Bond/Filtek Z250 (3M) resinous system was used for the specimen manufacture. The tensile bond strength tests were performed in a Universal Testing Machine with 50 kgf load cell and 0.5 mm/min cross head speed. The averages in MPa were: CA: 18.03 (+/-2.09); 11 mm; 9.92 (+/-3.34); 12 mm: 9.49 (+/-2.29); 14 mm: 10.99 (+/-3.45); 16 mm: 10.56 (+/-1.93); and 17 mm: 17.05 (+/-2.31). It was concluded that the application of Er:YAG laser in a defocused mode (17 mm) associated with acid etching was similar to the treatment of acid solely. Er:YAG laser irradiation in a focused (12 mm) and a defocused (11, 14, and 16 mm) mode coupled with acid conditioning produced the lowest values of adhesion.

  4. Effect of Nd:YAG laser on the solvent evaporation of adhesive systems.

    Batista, Graziela Ribeiro; Barcellos, Daphne Câmara; Rocha Gomes Torres, Carlos; Damião, Álvaro José; de Oliveira, Hueder Paulo Moisés; de Paiva Gonçalves, Sérgio Eduardo


    This study evaluated the influence of Nd:YAG laser on the evaporation degree (ED) of the solvent components in total-etch and self-etch adhesives. The ED of Gluma Comfort Bond (Heraeus-Kulzer) one-step self-etch adhesive, and Adper Single Bond 2 (3M ESPE), and XP Bond (Dentsply) total-etch adhesives was determined by weight alterations using two techniques: Control--spontaneous evaporation of the solvent for 5 min; Experimental--Nd:YAG laser irradiation for 1 min, followed by spontaneous evaporation for 4 min. The weight loss due to evaporation of the volatile components was measured at baseline and after 10 s, 20 s, 30 s, 40 s, 50 s, 60 s, 70 s, 80 s, 90 s, 100 s, 110 s, 2 min, 3 min, 4 min, and 5 min. Evaporation of solvent components significantly increased with Nd:YAG laser irradiation for all adhesives investigated. Gluma Comfort Bond showed significantly higher evaporation of solvent components than Adper Single Bond 2 and XP Bond. All the adhesives lost weight quickly during the first min of Nd:YAG laser irradiation. The application of Nd:YAG laser on adhesives before light curing had a significant effect on the evaporation of the solvent components, and the ED of Gluma Comfort Bond one-step self-etch adhesive was significantly higher than with Adper Single Bond 2 and XP Bond total-etch adhesives. The use of the Nd:YAG laser on the uncured adhesive technique can promote a greater ED of solvents, optimizing the longevity of the adhesive restorations.

  5. Simulation of medical Q-switch flash-pumped Er:YAG laser

    Wang Yanlin; Huang Chuyun; Yao Yucheng; Zou Xiaolin, E-mail:, E-mail:, E-mail:, E-mail: [Physics school, Hubei University of Technology, Wuhan, China 430068 (China)


    Er: YAG laser, the wavelength is 2940nm, can be absorbed strongly by water. The absorption coefficient is as high as 13000 cm{sup -1}. As the water strong absorption, Erbium laser can bring shallow penetration depth and smaller surrounding tissue injury in most soft tissue and hard tissue. At the same time, the interaction between 2940nm radiation and biological tissue saturated with water is equivalent to instantaneous heating within limited volume, thus resulting in the phenomenon of micro-explosion to removal organization. Different parameters can be set up to cut enamel, dentin, caries and soft tissue. For the development and optimization of laser system, it is a practical choice to use laser modeling to predict the influence of various parameters for laser performance. Aim at the status of low Erbium laser output power, flash-pumped Er: YAG laser performance was simulated to obtain optical output in theory. the rate equation model was obtained and used to predict the change of population densities in various manifolds and use the technology of Q-switch the simulate laser output for different design parameters and results showed that Er: YAG laser output energy can achieve the maximum average output power of 9.8W under the given parameters. The model can be used to find the potential laser systems that meet application requirements.

  6. High power CW diode-side-pumped Nd:YAG rod laser

    Hailin Wang(王海林); Weiling Huang(黄维玲); Zhuoyou Zhou(周卓尤); Hongbing Cao(曹红兵)


    We report on the characterization of a diode-side-pumped Nd:YAG rod laser operating at high CW output power. A four-fold pump configuration is designed and the pump light is directly coupled into the Nd:YAG rod without the help of any cylindrical lenses. The distribution of pump light in the Nd:YAG rod has been calculated by using ray tracing program. The thermal lens effect of the Nd:YAG rod has been experimentally measured. A maximum output power of 800 W at 1064 nm in multimode operation is obtained for a pump power of 2400 W with 33% optical-optical efficiency. At the same time, the maximum beam parameter product of 25 mm.mrad is achieved.

  7. Improvement of the surface finish obtained by laser ablation with a Nd: YAG laser on pre-ablated tool steel

    Steyn, J


    Full Text Available Surface finish is an important requirement for tool and die makers and remains a challenge with conventional machining technologies. Nd: YAG lasers have been utilised for many years in the area of laser marking, engraving and micro machining...

  8. In vitro effects of Nd:YAG laser radiation on blood: a quantitative and morphologic analysis

    Borrero, E.; Rosenthal, D.; Otis, J.B.


    Use of the Neodymium: yttrium -aluminum -garnet (Nd:YAG) laser to recanalize stenosed arteries may require delivery of the beam through blood. To assess the degree of hemolysis and debris formation, 54 samples of citrated whole blood were exposed to Nd:YAG laser radiation of varying powers (10, 20 and 30 watts) and duration (1, 2.5 and 5 seconds). Compared to control samples which were not subjected to laser light, there was no significant decrease in hematocrit (41 to 40.5 +/- 5%), hemoglobin concentration (13.8 to 13.8 +/- .06 g/1OO ml), or increase in free hemoglobin concentration. Debris weight (from .45 +/- .002 to .45 +/- .002 mg), as well as the white blood cell count, was also not significantly changed (from 5,400 to 5,200 +/- 240 WBC/cm). Light microscopy examination of debris from samples of whole blood, washed erythrocytes, and platelet-rich plasma subjected to the laser at 30 watts for five seconds failed to demonstrate the presence of membrane denaturation of blood elements, as compared with the morphologic changes observed in whole blood samples exposed to a hot tip rather than Nd:YAG laser radiation. Nd:YAG laser can be used intravascularly without fear of hemolysis or debris micro-embolization up to a power of 30 watts for five seconds.

  9. Treatment of Vascular Lesions of the Tongue with Nd:YAG Laser

    Joana Dias Coelho


    Full Text Available The treatment of vascular lesions of the tongue is a very challenging procedure since the maintenance of the lingual tissue is of critical importance. Numerous treatment options have been described in literature but the Nd:YAG Laser appears to be one of the safest therapeutic options. We described a successful treatment of vascular lesions of the tongue with an excellent clinical result after only one treatment session with the Nd:YAG laser, with conservation of the lingual tissue and its functionality.

  10. Optimization Of Output Q-Switched Nd:YAG Laser Based On Switching Time

    Tamuri, Abd Rahman; Daud, Yaacob Mat; Bidin, Noriah


    This paper reports the optimization of output Q-switch Nd:YAG. A free running Nd:YAG laser was employed as source of light. KD*P crystal was utilized as a Pockels cell. Avalanche transistor pulser was designed to switch a high voltage power supply. The switching time was conducted via a control unit based PIC16F84A microcontroller. The pulser was able to switch the voltage within 3 ns. The optimum switching time of Q-switching is obtained at 182.34 μs. The corresponding laser output is 40 mJ with pulse duration of 25 ns.

  11. Treatment of Special Renal Colic with Ureteroscope and Holmium YAG Laser

    沈明顺; 刘军


    Objective To investigate the method of emergent relief of special renal colicand treatment of ureter diseases causing renal colic. Methods By analyzing 63 cases of special re-nal colic treated with ureteroscope and Holmium YAG laser. Results 61 cases of renal colic were re-lieved in a short period of time and the ariginal ureter diseases causing renal colic were cured. Conclu-sion Special renal colic could be treated with ureteroscope and Holmium YAG laser in a quick and ef-fective manner.

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

    Batishche, Sergei A.


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

  13. About the luminescence properties of YAG:Nd, Ce and YAG:Nd single crystals and their relation to laser properties

    Mares, Jiri A.; Kubelka, Jiri; Kvapil, Jiri


    Laser excited luminescence studies of various YAG:Nd, Ce and YAG:Nd (with an excess of yttrium) single crystals together with a testing of laser properties of rods made from the same crystals have been investigated in this paper. It was observed that laser pulse energies increase with increasing halfwidths of the luminescence spectral bands. This dependence and other observations indicate that local structure changes or Nd(3+) nonequivalent centers are present in the studied crystals. Various mechanisms leading to the formation of Nd(3+) nonequivalent centers are discussed and it seems that the more probable mechanism is oxygen segregation and diffusion.

  14. Numerical Modelling of QCW-Pumped Passively Q-Switched Nd:YAG Lasers with Cr4+:YAG as Saturable Absorber

    WANG Yu-Ye; XU De-Gang; XIONG Jing-Ping; WANG Zhuo; WANG Peng; YAO Jian-Quan


    @@ Passively Q-switched quasi-continuous-wave (QCW) diode-pumped Nd:YAG laser with Cr4+:YAG as saturable absorber is numerically investigated by solving the coupled rate equations. The threshold pump rate for passively Q-switched QCW-pumped laser is derived. The effects of the pump rate and pump-pulse duration on the laser operation characteristics are studied theoretically. The pump power range can be estimated according to the number of output pulses. The numerical simulation results are in good agreement with the experimental results.

  15. Pulpal Thermal Changes following Er-YAG Laser Debonding of Ceramic Brackets

    Didem Nalbantgil


    Full Text Available Lasers are effective in debonding ceramic brackets. Unfortunately, while reducing the adhesive bond strength, lasers are also reported to increase pulpal temperature. The aim of this study was to evaluate the shear bond strengths and temperature increase levels after debonding ceramic brackets using an Er-YAG laser with or without water-cooling. Sixty polycrystalline upper premolar ceramic brackets were placed on the labial surface of sixty human premolar teeth which were randomly divided into three groups of twenty. A laser pulse at 5 W for 9 seconds was delivered to each bracket in both study groups either with water-cooling (water group or without water-cooling (waterless group using an Er-YAG laser. Debonding was performed 45 seconds after laser exposure and shear bond strengths were measured. Data comparison revealed a statistically significant difference between the groups. Mean temperature increases of 2.41°C and 4.59°C were recorded for the water and waterless laser groups, respectively. The shear bond strength value for the control group was 22.76 MPa and 10.46 and 6.36 MPa for the water and waterless laser groups, respectively. The application of Er-YAG laser with water-cooling was an efficient and safe method of debonding ceramic brackets.

  16. Effect of Nd:YAG laser capsulotomy on refraction in multifocal apodized diffractive pseudophakia.

    Vrijman, Violette; van der Linden, Jan Willem; Nieuwendaal, Carla P; van der Meulen, Ivanka J E; Mourits, Maarten P; Lapid-Gortzak, Ruth


    To evaluate the effect on refraction of neodymium:YAG (Nd:YAG) laser posterior capsulotomy for posterior capsule opacification (PCO), and to evaluate the correlation between automated and subjective refraction in multifocal apodized diffractive pseudophakia. A retrospective study of 75 pseudophakic eyes (50 patients) with multifocal apodized diffractive pseudophakia, treated for PCO with Nd:YAG laser posterior capsulotomy, was performed. Pre- and postintervention values of refractive and visual parameters were compared. The outcomes of autorefraction and subjective refraction were also compared. Uncorrected and corrected distance visual acuity improved significantly after Nd:YAG capsulotomy (Prefraction and autorefraction. Spherical equivalent changed significantly in autorefraction (P=.008), but not in subjective refraction. Autorefraction and subjective refraction were highly correlated in spherical equivalent, defocus equivalent, and blurring strength (r(2)>0.59). In approximately 7% of eyes, a change of more than 0.50 diopters in spherical equivalent in subjective refraction occurred. In most cases, Nd:YAG laser capsulotomy in patients with multifocal pseudophakia did not result in a change in refraction. However, 7% of eyes experienced a significant change in subjective refraction. Autorefraction correlated well with subjective refraction in apodized diffractive multifocal IOLs. Copyright 2012, SLACK Incorporated.

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

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


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

  18. Using transurethral Ho:YAG-laser resection to treat urethral stricture and bladder neck contracture

    Bo, Juanjie; Dai, Shengguo; Huang, Xuyuan; Zhu, Jing; Zhang, Huiguo; Shi, Hongmin


    Objective: Ho:YAG laser had been used to treat the common diseases of urinary system such as bladder cancer and benign prostatic hyperplasia in our hospital. This study is to assess the efficacy and safety of transurethral Ho:YAG-laser resection to treat the urethral stricture and bladder neck contracture. Methods: From May 1997 to August 2004, 26 cases of urethral stricture and 33 cases of bladder neck contracture were treated by transurethral Ho:YAG-laser resection. These patients were followed up at regular intervals after operation. The uroflow rate of these patients was detected before and one-month after operation. The blood loss and the energy consumption of holmium-laser during the operation as well as the complications and curative effect after operation were observed. Results: The therapeutic effects were considered successful, with less bleeding and no severe complications. The Qmax of one month postoperation increased obviously than that of preoperation. Of the 59 cases, restenosis appeared in 11 cases (19%) with the symptoms of dysuria and weak urinary stream in 3-24 months respectively. Conclusions: The Ho:YAG-laser demonstrated good effect to treat the obstructive diseases of lower urinary tract such as urethral stricture and bladder neck contracture. It was safe, minimal invasive and easy to operate.

  19. Effects of Nd:YAG laser pulpotomy on human primary molars.

    Liu, Jeng-fen


    The purpose of this study was to compare the effects of Nd:YAG laser pulpotomy to formocresol pulpotomy on human primary teeth. Patients with a primary tooth that required pulpotomy because of pulpal exposure to caries, were selected for this study. After removal of coronal pulpal tissue, Nd:YAG laser at 2 W, 20 Hz, 100 mJ or a 1:5 dilution of formocresol was introduced into the canal orifice for complete hemostasis. IRM paste was then placed over the pulp stump, and the tooth was restored either with composite resin or stainless steel crown. Sixty-eight teeth were treated with Nd:YAG laser and followed up for 6 to 64 months. Clinical success was achieved in 66 out of the 68 teeth (97 %), and 94.1 % were radiographically successful. In the control group, 69 primary molars were treated with formocresol and followed up for 9 to 66 months; 85.5 and 78.3% achieved clinical and radiographic success, respectively. The success rate of Nd:YAG laser pulpotomy was significantly higher than that of formocresol pulpotomy. The permanent successors of the laser-treated teeth erupted without any complications.

  20. Er:YAG laser ablation: 5-11 years prospective study

    Dostalova, Tatjana; Jelinkova, Helena; Nemec, Michal; Sulc, Jan; Miyagi, Mitsunobu


    The Er:YAG laser at 2940 nm has been proposed for use in dental cavity preparation and removal of carious enamel and dentin. The purpose of the present study was to determine the effect of the Er:YAG laser ablation in treating dental caries after a period from 5 to 11 years. For this study, 133 cavities were chosen, and for their reparation of it the three restorative materials were used. Baseline examination was made in the following intervals: one week, 1 year, and from 5 to 11 years after cavity preparation and placement of filling material. Clinical assessments were carried out in accordance with the US Public Health Service System. The follow-up included: the marginal ridge, marginal adaptation, anatomic form, caries, color match, cavo surface margin discoloration, surface smoothness, and postoperative sensitivity. Er:YAG laser ablation is an excellent method for treating frontal teeth, i.e., incisors, canines, premolars, and initial occlusal caries of molars. However, visual control of non-contact therapy is necessary. Er:YAG laser ablation is safe, and it strongly reduces pain. The laser treatment markedly decreases the unpleasant sound and vibration.


    Galia G. Zhegova


    Full Text Available The aim of this study was to evaluate adolescents’ acceptance and pain perception of Er-YAG laser preparation in comparison to conventional mechanical preparation. Material and methods: Forty four adolescents between the age of 16 and 18 years with bilateral matched pairs of carious permanent molars participated in this study. In each patient one of the 2 cavities was prepared conventionally, the other with the Er-YAG laser. All cavities were restored with light-cured composite resin following the application of acid etch and a bonding agent. The patients were instructed to rate pain (sensitivity during treatment according to visual analogue scale and to decide which method they would prefer for their future caries treatment. Results: The patients rated lower pain perception during laser treatment. It was found that 86.36 % of the adolescents indicated that they would prefer the Er:YAG laser preparation for further caries treatment. Conclusion: The application of the Er-YAG laser for carious tissue removal, compared to conventional mechanical preparation, is perceived as more comfortable and the adolescents prefer it for a future treatment.

  2. Evaluation of tissue tightening by the subdermal Nd: Yag laser-assisted liposuction versus liposuction alone

    Alberto Goldman


    Full Text Available Background: Skin tightening is a desirable outcome for skin flaccidity. Objective: We evaluated the applicability, safety, capacity and intensity of skin tightening with the subdermal 1,064 nm Nd: YAG laser application to the upper arms, and compared the results with liposuction. Materials and Methods: Patients with lipodystrophy and mild-to-severe skin laxity of the arms were included (n=28. In half of patients, a single treatment with a subcutaneous laser and liposuction was performed, while the other 14 had a regular liposuction. Treatment parameters, adverse effects and photographic documentation were recorded. Results: Aesthetic improvement and skin retraction was superior by laser lipolysis. The procedure was well tolerated without significant complications. Conclusions: The subdermal laser-assisted liposuction using a 1,064 nm Nd: YAG laser achieves improved skin tightening.

  3. Results of Endoscopic Treatment for Early Gastric Cancer by Nd-YAG Laser

    M. Tani


    Full Text Available We have introduced two endoscopic treatments for early gastric cancer: endoscopic mucosal resection using a cap-fitted panendoscope (EMRC, and endoscopic laser therapy using a Nd-YAG laser. Thirty-two patients (34 lesions with gastric cancer were treated by Nd-YAG laser; including 23 initial-therapy cases (25 lesions and 9 second-therapy cases representing failures of endoscopic mucosal resection or endoscopic ethanol injection. Endoscopic laser therapy was performed safely without complication in all patients. Three patients had residual cancer, and 2 of these required surgery. Six patients died from other disease. Endoscopic laser therapy can remove early gastric cancer even when the lesion has ulceration or submucosal invasion, and has a powerful hemostatic effect. It is a safe and effective treatment for early gastric cancer.

  4. The Overlapped Triple Circle Pulse Technique with Nd:YAG Laser for Refractory Hand Warts.

    Bingol, Ugur Anil; Cömert, Asuman; Cinar, Can


    Inadvertent superficial treatment of hand warts causes recurrence, whereas aggressive treatment can lead to tissue defects resulting in hand dysfunction. This study aimed to determine the effectiveness of a novel laser treatment modality for recalcitrant hand warts. The study included 51 patients who were treated for 146 recalcitrant hand warts using 1064 nm long-pulsed Nd:YAG laser between 2011 and 2014. The laser treatment method is novel because each treated wart was aligned at the intersection point of the circles of 3 laser pulses per session. Among the 146 hand warts, 88.35% were successfully treated with one session and 100% of those that required a second treatment session were treated successfully, based on the 12 month follow-up examination. Long-pulsed Nd:YAG laser treatment was observed to be a safe, rapid, and effective method for treating recalcitrant hand warts.

  5. A comparative SEM study between hand instrument and Er:YAG laser scaling and root planing.

    Moghare Abed, A; Tawakkoli, M; Dehchenari, M A; Gutknecht, N; Mir, M


    Scaling and root planing are one of the most commonly used procedures for the treatment of periodontal diseases. Removal of calculus using conventional hand instruments is incomplete and rather time-consuming. In search for more efficient and less difficult instrumentation, investigators have proposed lasers as alternatives or adjuncts for scaling and root planing. The aim of the present study was to compare the effectiveness of subgingival scaling and root planing with erbium: yttrium, aluminium, garnet (Er:YAG) laser and hand instrumentation in vitro. The mesial and distal surfaces of 15 periodontal loosed extracted teeth were treated randomly either by hand instrumentation or by Er:YAG laser irradiation. After choosing the "very long pulse mode" (pulse duration of about 700 micros), the output energy of 160 mJ with 920-microm beam diameter (RO7 Perio tip, Fidelis, Fotona, Slovenia) and frequency of 12 Hz were selected, both according to the best results of past studies. In addition, air water spray was used during the procedures. The morphology of the root surface was evaluated by three observers with a scanning electron microscopy in magnifications of 50x and 400x. The result of this setting showed that the rate of remained roughness on treated root surfaces in two groups of hand instruments and Er:YAG laser had a meaningful difference: The surface roughness in Er:YAG laser group was more than in hand instruments group. The present study could demonstrate the in vitro capability of the Er:YAG laser for scaling and root planing in periodontitis, although the effectiveness of this setting did not reach that achieved by hand instrumentation. It could be concluded that lower frequency and long pulse duration maybe more suitable for the micro-morphology of root surface after treatment. This theory is going to be tested with the same laser instrument in the next study.

  6. Effects of Nd:YAG laser radiation in cultured porcine vertebral disc tissue

    Thal, Dietmar R.; Werkmann, Klaus; Leheta, Fouad; Schober, Ralf; Ulrich, Peter


    Nd:Yag laser radiation is used for the treatment of protrusion of intervertebral discs. It is known that laser radiation leads to coagulation, vaporization and carbonization of the disk. Little is known about the early changes in vertebral discs after laser radiation. Therefore, we exposed cadaveric porcine vertebral discs by Nd:YAG laser radiation immediately after death. The discs were quartered and either formalin fixed after laser radiation or kept in culture for 1, 4 and 7 days and then formalin fixed. Immunohistochemistry was performed with antibodies directed against vimentin and amyloid precursor protein (APP). Results showed a jerky leak of notochordial remnant cells and mucopolysaccharides at the distal end of the application needle during laser radiation, which was interpreted as a bursting extrusion of damaged but not vaporized tissue. Histology and immunohistochemistry revealed an incomplete loss of nucleus pulposus and a large, almost complete necrosis of the notochordial remnant cells. In surviving notochordial remnant cells after laser radiation a slight increase of vimentin and APP could be seen without any other cellular reactions. The annulus fibrosus showed no significant changes except a defect with a small necrosis zone at the site of the application needle. Therefore, it can be concluded that Nd:YAG laser radiation leads to an increased volume reduction by the leak of nucleus pulposus and to a slight cellular reaction of surviving notochordal remnant cells detectable by vimentin and APP increase.

  7. Response of feline intradental nerve fibers to tooth cutting by Er:YAG laser.

    Chaiyavej, S; Yamamoto, H; Takeda, A; Suda, H


    The aim of this study was to investigate the response of intradental A- and C-fibers during tooth cutting by Er:YAG laser. Bipolar electrical stimulation was applied to the cat's canine to identify functional single nerve fibers of the inferior alveolar nerve. The tip of the canine tooth was cut in 0.5-mm steps until the pulp was exposed. Teeth were alternately cut by using Er:YAG laser (50 mJ, 5 pps) and micromotor under water cooling. The nerve response recorded from the single nerve fibers during laser cutting was compared with that during micromotor cutting. All 26 A-fibers responded to laser cutting with high frequency of nerve firings. The nerve firing rate was significantly higher during laser cutting compared with that during micromotor cutting of superficial dentin (Chi(2) test, P or = 0. 05). Nine of 11 C-fibers responded to laser cutting when the deep dentin was cut. Among those nine nerve fibers, three also showed a low frequency response to laser cutting of the superficial dentin. During the tooth cutting, Er:YAG laser was more effective in activating intradental A-fibers compared with micromotor and also caused the activation of intradental C-fibers. Copyright 2000 Wiley-Liss, Inc.

  8. Comparison of SHR Mode IPL System with Alexandrite and Nd: YAG Lasers For Leg Hair Reduction

    Şemsettin Karaca


    Full Text Available Objective: Multiple lasers and light sources are currently available for hair removal and many studies comparing efficacy and safety exist. SHR mode IPL is a technique that gives the total energy in divided doses with fewer side effects. We compared a SHR mode IPL system with alexandrite and Nd: YAG lasers for leg hair reductionMaterial and Methods: Twenty-five female participants with skin types II–IV, underwent treatment of unwanted hair on the cruris. Three selected areas were randomly treated with the SHR mode IPL system, Alexandrite laser and Nd: YAG laser in three sessions. Hair reduction was evaluated with digital photography by a blinded assessor every 6 weeks and 6 months after the last session. Pain severity, side effects and patient satisfaction analysis were also investigated. Results: Twenty-one participants completed the trial. The mean hair reductions in 6 weeks after the last treatment were 50% for the IPL system, 53% for Alexandrite and 39% for the Nd: YAG lasers. However after 6 months; 40%, 49% and 34% hair reduction was observed, respectively. The Alexandrite laser was the least painful system. Conclusion: Although there is no obvious advantage of one laser system over the others in terms of treatment outcome, the Alexandrite laser is still the most efficient and reliable way of hair removal in fair skinned individuals.

  9. Laser Cleaning Using Q-Switched Nd:YAG Laser of Low Carbon Steel Alloys

    S. N. Ali


    Full Text Available This paper represents the efforts to achieve the laser cleaning process of low carbon steel alloys AISI1005 and AISI1012 with 0.65 mm and 1 mm thickness, respectively. The cleaning experiments were performed with a Q-switched Nd:YAG nanosecond laser at wavelengths of 1064 nm and 532 nm. The parameters that have been selected for the present work are peak power which varies as 5, 15, 30, 40, and 50 MW and pulse repetition rate which varies from 1 to 6 Hz by 1 Hz increment. Effects of these parameters on the microstructure and the mechanical properties of the two alloys have been realized. Also predicted results of analytical model regarding the depth were compared with the experimental results which show a good agreement between both.

  10. Bouveret's syndrome complicated by distal gallstone ileus after laser lithotropsy using Holmium: YAG laser

    Rodgers John B


    Full Text Available Abstract Background Bouveret's syndrome is an unusual presentation of duodenal obstruction caused by the passage of a large gallstone through a cholecystoduodenal fistula. Endoscopic therapy has been used as first-line treatment, especially in patients with high surgical risk. Case presentation We report a 67-year-old woman who underwent an endoscopic attempt to fragment and retrieve a duodenal stone using a Holmium: Yttrium-Aluminum-Garnet Laser (Ho:YAG which resulted in small bowel obstruction. The patient successfully underwent enterolithotomy without cholecystectomy or closure of the fistula. Conclusion We conclude that, distal gallstone obstruction, due to migration of partially fragmented stones, can occur as a possible complication of laser lithotripsy treatment of Bouveret's syndrome and might require urgent enterolithotomy.

  11. Continuous-wave theory of Yb:YAG end-pumped thin-disk lasers.

    Jafari, Ahmad Khayat; Aas, Mehdi


    The fundamental principles of the operation of a thin-disk laser are presented. We derived equations from a set of coupled rate equations that predict that the characteristics of a laser are affected by the Boltzmann occupation factors of the pump and the laser states simultaneously. The model is used to investigate the influence of the effective parameters on the operational efficiency of an end-pumped Yb:YAG disk laser. Based on our results, we examined laser output power as a function of output coupler reflectivity, crystal thickness or doping concentration, number of the pump beam passes, and temperature.

  12. Basic studies on laser-assisted phacoemulsification using diode-pumped Er:YAG laser

    Hausladen, Florian; Wurm, Holger; Stock, Karl


    The aim of this study was to determine the potential of a novel diode-pumped Er:YAG laser for phacoemulsification in basic experimental investigations. An appropriate experimental setup was created, including a translation stage for sample movement, a sample holder, a water spray for sample humidification and a surgical microscope with a CCD camera for video documentation. The analysis of the laser cuts and histological sections was done by light microscopy. As samples porcine eye lenses hardened by formalin were used. In ablation experiments with different spot diameters and radiant powers and a constant repetition rate νr = 200 Hz the maximum ablation depths of (4.346 +/- 0.044) mm have reached at (Ø = 480 μm, Φ = 24.15 W) with a maximum extend of thermal damage of (0.165 +/- 0.030) mm. The average ablation efficiency is 0.241 mm3/J. With a spot diameter of 308 μm the maximum ablation depth is (4.238 +/- 0.040) mm at 24.65 W with a mean ablation efficiency of 0.293 mm3/J. The extend of the thermally damaged region is (0.171 +/- 0.024) mm at this laser power. Using a sapphire cylinder with a diameter of 412 μm (length 38.5 mm) in direct tissue contact with water spray for sample humidification the ablation depth reaches (1.017 +/- 0.074) mm at 4.93 W and (1.840 +/- 0.092) mm at 9.87 W with a mean efficiency of 0.261 mm3/J. A thermal damage zone of (0.064 +/-0.024) mm at 9.87 W was measured. Additionally, at this high power, a progressive contamination and destruction of the cylinder end facet was observed. In conclusion, the investigations show that the diode-pumped Er:YAG laser has considerable potential for cataract surgery.

  13. High-repetition-rate femtosecond dye amplifier using a laser-diode-pumped neodymium:YAG laser

    Zysset, B.; LaGasse, M.J.; Fujimoto, J.G.; Kafka, J.D.


    A high-repetition-rate femotosecond dye amplifier is demonstrated using a laser-diode-pumped Q-switched Nd:YAG laser. Amplification of wavelength-tunable 300-fs pulses from a synchronously mode-locked rhodamine dye laser is achieved with a saturated gain of 70 and a small gain of 200 at a repetition rate of 800 Hz. Maximum pulse energies of 40 nJ are obtained, and pulse compression to as short as 30 fs is demonstrated.

  14. [Use of the thermal laser effect of laser irradiation for cardiovascular applications exemplified by the Nd:YAG laser].

    Ischinger, T; Coppenrath, K; Weber, H; Enders, S; Unsöld, E; Hessel, S


    Techniques of percutaneous transluminal application of laser energy for vessel recanalization have been used clinically since 1983. The commonly used Nd:YAG and argon lasers achieve ablation of atherosclerotic plaques by thermal action (vaporization). In order to reduce undesirable thermal damage in the neighborhood of the target tissue and to avoid vessel perforation, optimal irradiation parameters, modified (atraumatic) fiber tips (hot tips, sapphires), and steerable catheter systems needed to be implemented. Favorable results from peripheral application have encouraged use in the coronary circulation. More recently, coagulative tissue effects of circumferential irradiation of the vessel wall during balloon dilatation have been used for stabilization of acute and late results after mechanical balloon angioplasty. Enhancement of the differential light absorption of atherosclerotic plaque by use of biological dyes may further improve selective intravascular laser application. Intraoperative ECG-guided laser coagulation of arrhythmogenic areas of myocardium is a method for treatment of malignant arrhythmias. Transluminal non-operative application of myocardial laser photocoagulation has now been tested experimentally and shown to be safe and effective. There was no arrhythmogenicity or thermal damage of coronary arteries associated with this method. Innovative techniques such as nanosecond pulsed excimer lasers (athermal action) and development of "intelligent" lasers--which are equipped with spectroscopy-guided feedback systems for plaque recognition--have opened new perspectives and will further improve safety and efficacy of clinical laser application. However, according to current experience, the thermally acting Nd:YAG laser is an effective and versatile mode of laser therapy for selected cardiovascular indications.

  15. Ureteropyeloscopy and homium: YAG laser lithotripsy for treatment of ureteral calculi (report of 356 cases)

    Wu, Zhong; Din, Qiang; Jiang, Hao-wen; Zen, Jing-cun; Yu, Jiang; Zhang, Yuanfang


    Objective: To evaluate the efficacy and safety of holmium YAG laser lithotripsy for the treatment of ureteral calculi. Methods: A total of 356 patients underwent ureteropyeloscopic lithotripsy using holmium YAG laser with a semirigid uretesopyeloscope, 93 upper, 135 middle, and 128 lower ureteral stones were treated. Results: The overall successful fragmentation rate for all ureteral stones in a single session achieved 98% (349/356). The successful fragmentation rate stratified by stone location was 95% 88/93 in the upper ureter, 99% (134/135) in the mid ureter , and 99%(127/128) in the distal ureter. 12 cases with bilateral ureteral stones which caused acute renal failure and anuria were treated rapidly and effectively by the holmium YAG laser lithotripsy. No complications such as perforation and severe trauma were encountered during the operations. 2 weeks 17months (with an average of 6.8 month ) follow up postoperatively revealed that the overall stone-free rate was 98%(343/349) and no ureteral stenosis was found. Conclusions Holmium YAG laser lithotripsy is a highly effective, minimally invasive and safe therapy for ureteral calculi. It is indicated as a first choice of treatment for patients with ureteral calculi, especially for the ones with mid- lower levels of ureteral calculi.

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

    Batishche, Sergei A.


    It is shown that infra-red ((lambda) equals 1064 nm) long pulse (approximately 100 microsecond(s) ) radiation of YAG:Nd laser, operating in free generation regime, effectively fragments gallstones, urinary calculus and kidney stones. The features of the mechanism of this process are investigated.

  17. Cutting and coagulation during intraoral soft tissue surgery using Er: YAG laser.

    Onisor, I; Pecie, R; Chaskelis, I; Krejci, I


    To find the optimal techniques and parameters that enables Er:YAG laser to be used successfully for small intraoral soft tissue interventions, in respect to its cutting and coagulation abilities. In vitro pre-tests: 4 different Er:YAG laser units and one CO2 unit as the control were used for incision and coagulation on porcine lower jaws and optimal parameters were established for each type of intervention and each laser unit: energy, frequency, type, pulse duration and distance. 3 different types of intervention using Er:YAG units are presented: crown lengthening, gingivoplasty and maxillary labial frenectomy with parameters found in the in vitro pre-tests. The results showed a great decrease of the EMG activity of masseter and anterior temporalis muscles. Moreover, the height and width of the chewing cycles in the frontal plane increased after therapy. Er:YAG is able to provide good cutting and coagulation effects on soft tissues. Specific parameters have to be defined for each laser unit in order to obtain the desired effect. Reduced or absent water spray, defocused light beam, local anaesthesia and the most effective use of long pulses are methods to obtain optimal coagulation and bleeding control.

  18. Stable mode-locking in an Yb:YAG laser with a fast SESAM

    Guifang Ju(居桂方); Lu Chai(柴路); Qingyue Wang(王清月); Zhigang Zhang(张志刚); Yonggang Wang(王勇刚); Xiaoyu Ma(马骁宇)


    Stable mode-locking in a diode-pumped Yb:YAG laser was obtained with a very fast semiconductor saturable absorber mirror (SESAM). The pulse width was measured to be 4 ps at the central wavelength of 1047 nm. The average power was 200 mW and the repetition rate was 200 MHz.

  19. Study on CW Nd:YAG infrared laser at 1319 nm

    Tao Wang (王涛); Jianquan Yao (姚建铨); Guojun Yu (禹国俊); Peng Wang (王鹏); Xifu Li (李喜福); Yizhong Yu (于意仲)


    A continuous wave (CW) Nd:YAG infrared laser at 1319 nm is reported in this paper. The energy level of 1319-nm wave was analyzed. The repression of 1064-nm lasing and enhancement of 1319-nm output power were discussed. Mirror coating and cavity structure were studied and a maximum CW output power of 43W at 1319 nm was achieved in experiments.

  20. Nd:YAG laser treatment of herpes and aphthous ulcers: a preliminary study

    Parkins, Frederick M.; O'Toole, Thomas J.; Yancey, John M.


    Previously herpes labialis and recurrent aphthous ulcers have not been successfully treated. A preliminary study with a pulsed Nd:YAG laser evaluated the results with a protocol of four minute non-contact exposures for both types of lesions. Most patients experienced relief of symptoms. The progress of herpes lesion was halted and aphthous lesions became desensitized.

  1. Nd:YAG laser in urogenital surgery of the dog and cat

    van Nimwegen, S.A.


    It was hypothesized that the fiber-guided Nd:YAG laser with its incisional and hemostatic action, could be useful for meticulous tissue dissection in a subcapsular partial prostatectomy in dogs, and in laparoscopic surgery of dogs and cats. Prior to clinical use, its action was investigated in vitro

  2. Nd:YAG laser in urogenital surgery of the dog and cat

    van Nimwegen, S.A.


    It was hypothesized that the fiber-guided Nd:YAG laser with its incisional and hemostatic action, could be useful for meticulous tissue dissection in a subcapsular partial prostatectomy in dogs, and in laparoscopic surgery of dogs and cats. Prior to clinical use, its action was investigated in

  3. Selective removal of carious lesion with Er:YAG laser followed by dentin biomodification with chitosan.

    Curylofo-Zotti, Fabiana A; Tanta, Gabriela Solano; Zucoloto, Miriane Lucindo; Souza-Gabriel, Aline E; Corona, Silmara A M


    The aim of this study was to evaluate the effect of Er:YAG laser for selective removal of carious lesion, followed by biomodification with chitosan gel where the subsurface microhardness, chemical composition, and morphological changes of the residual caries-affected dentin were examined. Artificial dentinal lesions were created by pH-cycling method (14 days) in 104 bovine specimens (5 × 5 mm). Specimens were randomly divided according to the carious removal method: bur (low-speed handpiece) or Er:YAG laser (250 mJ/4 Hz). Specimens were treated with 35% phosphoric acid and were subdivided into two groups according to dentin biomodification: without chitosan (control) and 2.5% chitosan. Forty specimens were restored with an adhesive system and composite resin. Subsurface microhardness tests were performed in sound dentin, caries-affected dentin, residual caries-affected dentin, and after the restoration. The other 64 specimens were subjected to SEM-EDS atomic analysis. Data were statistically analyzed (p carious lesions with Er:YAG laser (p  0.05). SEM analysis showed morphological changes on residual caries-affected dentin (p > 0.05). The selective removal of carious dentin with Er:YAG laser increased microhardness of residual caries-affected dentin, changing its surface morphology and chemical composition. The biomodification with chitosan did not influence the structural and chemical composition of residual caries-affected dentin.

  4. Study of diode-pumped Yb:YAG disk lasers at low temperature

    Jianlei Wang; Zhenhua Zhang; Xiaojin Cheng; Lei Li; Xiangchun Shi; Xiaolei Zhu; Weibiao Chen


    A Yb:YAG disk laser with V-shaped stable resonator and active-mirror configuration, end-pumped by a 940-nm InGaAs laser diode array, is demonstrated. Performances and optimization of the disk laser at low temperature over a range of 130-200 K are investigated theoretically and experimentally. Laser output energy of 1.46 J/pulse operating at 10-Hz repetition rate is obtained with the optimum output coupler transmission of 30%, and the corresponding optical-to-optical efficiency is 48.7%.%Yb:YAG[1-4],by virtue of its high quantum efficiency (>90%),long life time,no concentration quenching,no excite-state absorption,and no upconversion effect,has recently been considered as a suitable candidate for lasers with high average power and high efficiency[5-7].Due to their wide absorption band centered at 941 nm,Yb:YAG lasers are more acceptable for variation of pump laser diode (LD) wavelength.

  5. Photothermal ablation is the primary mechanism in holmium:YAG laser lithotripsy of urinary calculi

    Glickman, Randolph D.; Teichman, Joel M. H.; Corbin, Nicole S.; Vassar, George J.; Weintraub, Susan T.; Chan, Kin Foong; Welch, Ashley J.


    Because of the >= 250 microsecond(s) pulsewidth emitted by the Ho:YAG laser used in clinical lithotripsy, it is unlikely that stress confinement occurs within the irradiated stones. Experimental data supports a thermal mechanism for Ho:YAG laser stone ablation. Previous work has shown that stone fragmentation occurs soon after the onset of the laser pulse, is uncorrelated to cavitation bubble formation or collapse, and is associated with low pressures. Moreover, lithotripsy proceeds fastest with desiccated stones in air (data based on laser ablation of calcium oxalate monohydrate stones), indicating that direct absorption of the laser radiation by the stone material is required for the most efficient ablation. Lowering the initial temperature of calculi reduces the stone mass-loss following 20 J of delivered laser energy: 2.2 +/- 1.1 mg vs 5.2 +/- 1.6 mg for calcium oxalate monohydrate (COM) stones (-80 vs 23 degree(s)C), and 0.8 +/- 0.4 mg vs 2.2 +/- 1.1 mg for cystine stones (-80 vs 23 degree(s)C), p cystine; Ca2O7P2 from calcium hydrogen phosphate dihydrate, and cyanide and alloxan from uric acid. All of these observations are most consistent with a photothermal breakdown process induced by Ho:YAG laser lithotripsy.

  6. The applications of diode and Er:YAG lasers in labial frenectomy in infant patients.

    Gontijo, Isa; Navarro, Ricardo S; Haypek, Patrícia; Ciamponi, Ana Lídia; Haddad, Ana Estela


    This paper describes a clinical case of labial frenectomy using different high power lasers: diode (810 nm) and Er:YAG (2940 nm). Considerations are made about specific indications, surgery techniques, and advantages of labial frenectomy using these laser wavelengths. The diode laser has high absorbance by pigmented tissues with hemoglobin, melanin, and collagen chromophores. For this reason, this wavelength is well indicated for surgery in soft tissue (vaporization, incision, coagulation, hemostasis). It is not properly absorbed, however, and should never be used in contact with hard tissues (bone). The Er:YAG laser has high absorbance to water and mineral apatite, making this wavelength useful and safe for the ablation of hard tissues. In the labial frenectomy clinical procedure, a combined technique is suggested: using the diode laser in soft tissues and the Er:YAG laser in periosteal bone tissues and for removal of final collagen fibers. It is important for the professional to understand the physical characteristics of the different laser wavelengths and their interaction with biological tissues to assure that they are used in a safe way, and that the benefits of this technology can be provided to infant patients.

  7. Comparison of laser performance of electro-optic Q-switched Nd:YAG ceramic/single crystal laser

    Jianghua Ji; Xiaolei Zhu; Chunyu Wang; Yongwei Feng; Qihong Lou


    @@ An electro-optic Q-switched Nd:YAG ceramic laser operating at kHz repetition rate was demonstrated.Thermal induced lens' focus of ceramic rod was measured and compensated by plano-convex cavity structure. Depolarization loss at different output powers was measured in Nd:YAG single crystal and ceramic lasers. High-energy high-beam-quality laser pulse output was obtained in both laser structures. Pulse energy of about 20 mJ and pulse width of less than 12 ns were achieved, and the average power reached 20 W. The divergence of output laser beam was less than 1.2 mrad, and the beam propagation factor M2was about 1.4.

  8. Measurement of pulse lengthening with pulse energy increase in picosecond Nd:YAG laser pulses

    Cutolo, A.; Zeni, L.; Berardi, V.; Bruzzese, R.; Solimeno, S.; Spinelli, N.


    Taking advantage of a new technique, we have monitored the relative variations of time duration and mode size as a function of the pulse energy for 30-ps-long Nd:YAG laser pulses. In particular, by carrying out a statistical analysis, we have observed that the pulse time duration is an increasing function of the pulse energy, according to the theoretical modeling of passively mode-locked lasers. The measurements can be easily extended to the femtosecond regime.

  9. Clinical, radiographic, and histopathologic evaluation of Nd:YAG laser pulpotomy on human primary teeth.

    Odabaş, Mesut Enes; Bodur, Haluk; Bariş, Emre; Demir, Cem


    The purpose of this study was to compare clinical, radiographic, and histopathologic effects of Nd:YAG laser pulpotomy to formocresol pulpotomy on human primary teeth. Patients with at least two vital primary molar teeth that required pulpotomy, because of pulpal exposure to caries, were selected for this study. After hemorrhage control, complete hemostasis into the canal orifice was achieved by exposure to Nd:YAG laser (1064 nm) and an He-Ne laser (the aiming beam of the Nd:YAG laser) in noncontact mode at 2 W, 20 Hz, 100 mJ, or was achieved by applying 1:5 dilution of formocresol. Forty-two teeth in two groups were to be followed up clinically and radiographic at 1, 3, 6, 9, and 12 months. Eighteen teeth planned for serial extractions were selected for histopathologic study. The teeth were extracted at 7 and 60 days. The teeth in the laser group had a clinical success rate of 85.71% and a radiographic success rate 71.42% at 12 months. The teeth in the formocresol group had a clinical and radiographic success rate of 90.47% at 12 months. There were no statistically significant differences between laser and formocresol group with regard to both clinical and radiographic success rates. There was a statistically significant difference between 7- and 60-day laser groups with regard to inflammatory cell response criteria. Dentin bridge was absent in all samples. No stained bacteria were observed in any of these samples. In conclusion, Nd:YAG laser may be considered as an alternative to formocresol for pulpotomies in primary teeth.

  10. Frequency-stabilized diode-pumped Nd:YAG laser of high power

    Taccheo, S.; Laporta, P.; Longhi, S. [CNR, Milano (Italy). Centro di Elettronica Quantistica e Strumentazione Elettronica]|[Politecnico di Milano (Italy). Dipt. di Fisica; Svelto, C. [Politecnico di Milano (Italy). Dipt. di Elettronica e Informazione


    The authors describe a frequency-stabilized diode-pumped Nd:YAG laser of high power whose single-mode operation is obtained by suppressing the spatial hole burning through the twisted-mode technique. Active frequency stabilization is achieved by fringe side locking the laser beam to a reference Fabry-Perot cavity. Output power up to 800 mW in single-transverse and -longitudinal mode operation with a linewidth of less than 20 kHz is obtained.


    Brigita Drnovšek-Olup


    Full Text Available Background. In this study, a new type of Er:YAG laser, emitting irradiation with variable pulse duration, has been used for blepharoplasty and skin resurfacing in periocular region.More than 40 patients have been treated with second generation Er:YAG laser (Fotona Fidelis for blepharoplasty and skin resurfacing. A focused laser beam (diameter 0.4 mm with very short pulse width (100 µs, that is significantly below the thermal relaxation time of skin, leads to a precise cut with no observable thermal effect on surrounding tissue. The depth of the cut is approximately 1–2 mm, precision comparable to a surgical scalpel. The high repetition rate of consecutive laser pulses (50 Hz at 120 mJ energy accounts for accumulation of thermal load in tissue, and thus leads to complete hemostasis of the cut tissue. Due to improved cutting abilities of the Er:YAG laser, excision of orbital fat is also performed with one pass of the laser beam. By changing the laser parameters to short pulses (300 µs, energy 500 mJ, spot diameter 5 mm and repetition rate 12–15 Hz, skin resurfacing was performed. No special pretreatment therapy was used. Anesthesia: 2% Xylocain inj. subcutaneously. Non adhesive dressing for 24 hours was applied after surgery.Epithelisation was complete after ten days. Redness persists up to 5 weeks. Discomfort of patients was mild. Cosmetic results are satisfying.Conclusions. New generation of Er:YAG laser offers a possibility to cut and coagulate the tissue simultaneously, and by changing the parameters to ablate the tissue with heating influence on skin collagen.

  12. Dynamics of two coupled chaotic multimode Nd:YAG lasers with intracavity frequency doubling crystal

    Thomas Kuruvilla; V M Nandakumaran


    The effect of coupling two chaotic Nd:YAG lasers with intracavity KTP crystal for frequency doubling is numerically studied for the case of the laser operating in three longitudinal modes. It is seen that the system goes from chaotic to periodic and then to steady state as the coupling constant is increased. The intensity time series and phase diagrams are drawn and the Lyapunov characteristic exponent is calculated to characterize the chaotic and periodic regions.

  13. Nd:YAG laser bloodless tonsillectomy by fiber optic doppler coupled handpiece beam delivery

    Palmieri, Beniamino; Rottigni, Valentina


    Laser ablation of palatine tonsils is a relatively new technique recently performed in head and neck surgery departments, in order to treat recurrent tonsillar infections or obstructions from enlarged tonsils. In our study, we have investigated a new procedure using the fiber optic laser beam Nd:YAG to remove up to the 89% of tonsillar tissue, and leaving in place the capsule avoiding any hemorrhagic complication and limiting the pain.

  14. A Case Report of Telangiectatic Rosacea Treated with Long Pulsed Nd-YAG Laser

    Can Ergin


    Full Text Available Rosacea is a chronic enflammatory skin disease characterized by facial erythema, telangiectasia, papules and pustules. A variety of topical and systemic medications are used in the treatment of the disease. Recently, erythema and telangiectasia in rosacea patients have been frequently treated with laser applications. Herein, we present a case of rosacea whose telangiectasia were successfully treated with Nd-YAG laser treatment. 

  15. 2940-nm Er:YAG fractional laser enhanced the effect of topical drug for psoriasis.

    Li, Ruilian; Zhou, Jun; Su, Hui; Wang, Mei; Wang, Yongxian; Xiao, Shengxiang; Ma, Huiqun


    We observed the promoting effects of the 2940-nm erbium:YAG (Er:YAG) fractional laser in topical drug delivery for psoriasis. A total of five (four males and one female) recalcitrant psoriasis patients were given laser treatment eight times at 1-week intervals with the following parameters: 5-11% spot density and 100-μm energy depth. The psoriatic skin lesions on the left knee and the corresponding lesions at the right ones of each psoriasis patient were randomly divided into two groups: laser + topical drug group (L) and drug alone group (D). The psoriatic lesions in both groups were treated with the same topical treatment (calcipotriol ointment). The corresponding psoriatic lesions in the L group received extra 2940-nm Er:YAG laser irradiation before topical treatment. The photos of psoriatic lesions were taken before each treatment. The final photos were obtained from the patients at the seventh day after the final treatment. Drug alone or in combination with laser Er:YAG both reduced psoriatic lesions. However, with the increase in the number of treatments, increasing differences were observed between the treatment and the control sides. The therapeutic outcomes in the L groups were better than those in the D groups. Psoriasis area and severity index (PASI) scores for five cases of both groups were decreased. However, the scores in the L groups were lower than those in the D groups. The use of 2940 nm Er:YAG promoted the absorption of topical drugs for psoriasis, improving the therapeutic effect.

  16. Effect of Er:Yag laser on dentin demineralization around restorations.

    Chinelatti, Michelle Alexandra; Rocha, Cristiane Tomaz; Colucci, Vivian; Serra, Mônica Campos; Rodrigues-Júnior, Antonio Luiz; Corona, Silmara Aparecida Milori


    The aim of this study was to evaluate the effect of cavity preparation with Er:YAG laser on dentin adjacent to restorations submitted to cariogenic challenge in situ, by subsuperficial microhardness analysis. Bovine incisors were sectioned, flattened, and polished, resulting in 40 dentin slabs. The slabs were randomly assigned to four groups (n = 10), according to the cavity preparation method: I-high-speed handpiece (control); II-Er:YAG laser (160 mJ; 3 Hz); III-Er:YAG laser (260 mJ; 3 Hz); IV-Er:YAG laser (300 mJ; 3Hz). Cavities were restored with composite resin, and the specimens were fixed in intra-oral appliances, which were worn by 10 volunteers for 14 days for simulating cariogenic challenge in situ. During the experimental period, 20% sucrose solution was dripped over each specimen 6 times a day. Samples were removed, sectioned, and examined for subsuperficial Knoop microhardness at 100, 200, and 300 μm from the restoration and at 30 μm from dentin surface. Split-plot analysis of variance showed no significant difference among the cavity preparation techniques (p = 0.1129), among distances (p = 0.9030), as well as no difference in the interaction between the main factors (p = 0.7338). It was concluded that the cavity preparation with Er:YAG laser did not influence on dentin microhardness submitted to cariogenic challenge in situ.

  17. Role of Nd:YAG laser for prevention of neuroma formation: an in vivo experimental study.

    Elwakil, Tarek F; Elkharbotly, Ahmad


    Nerve transection is commonly followed by the development of neuroma at the proximal stump. It can be very painful especially at exposed sites. It may arise spontaneously or after mechanical irritation. Neuroma and its high recurrence rate might be resisting problems to treat. Various treatment modalities for neuroma and its recurrence have been proposed, but none has provided satisfactory results. The present study was conducted to evaluate the neodymium:yttrium aluminum garnet (Nd:YAG) laser (1,064 nm) nerve transection technique for prevention of neuroma formation. There were 48 facial nerves out of 24 Rex rabbits divided into two equal groups. The 24 left-sided facial nerves at group A were subjected to Nd:YAG laser for nerve transection, while the 24 right-sided facial nerves at group B were subjected to scalpel nerve transection. The results were grossly and histopathologically evaluated. Grossly, laser-transected nerves showed an infrequent incidence of neuroma formation. Histopathologically, laser-transected nerves showed photothermal degenerative changes of the axons and myelin sheaths with intact perineurium and endoneurium. No Schwann cell hyperactivity could also be elicited among laser-transected nerves. Nd:YAG laser was found to be an effective tool that could be applied, whenever it is possible, for division of major nerves to prevent the formation of the subsequent stump neuroma. Moreover, this technique should be considered during treatment of well-established neuroma to prevent the challenging reported high incidence of recurrence.

  18. Selective removal of dental caries with a diode-pumped Er:YAG laser

    Yan, Ruth; Chan, Kenneth H.; Tom, Henry; Simon, Jacob C.; Darling, Cynthia L.; Fried, Daniel


    Selective removal of caries lesions with high precision is best accomplished using lasers operating at high pulse repetition rates utilizing small spot sizes. Conventional flash-lamp pumped Er:YAG lasers are poorly suited for this purpose, but new diode-pumped Er:YAG lasers have become available operating at high pulse repetition rates. The purpose of this study was to measure the ablation rate and selectivity of sound and demineralized enamel and dentin for a 30 W diode-pumped Er:YAG laser operating with a pulse duration of 20-30-μs and evaluate it's potential for the selective removal of natural occlusal lesions on extracted teeth. Microradiography was used to determine the mineral content of the demineralized enamel and dentin of 300-μm thick sections with natural caries lesions prior to laser ablation. The ablation rate was calculated for varying mineral content. In addition, near-IR reflectance measurements at 1500-1700- nm were used to guide the laser for the selective ablation of natural occlusal caries lesions on extracted teeth.

  19. The analysis of the transient temperature distribution of double-slab Nd:YAG laser medium

    Yan Huang; Junqing Meng; Lingling Zhang; Qiquan Hu


    A novel double-slab Nd:YAG laser, which uses face-pumped slab medium cooled by liquid with different temperatures on both sides, is proposed. The thermal distortion of wavefront caused by the non-uniform temperature distribution in the laser gain media can be self-compensated. According to the method of operation, the models of the temperature distribution and stress are presented, and the analytic solutions for the model are derived. Furthermore, the numerical simulations with pulse pumping energy of 10 J and repetition frequencies of 500 and 1000 Hz are calculated respectively for Nd:YAG laser medium. The simulation results show that the temperature gradient remains the approximative linearity, and the heat stress is within the extreme range. Then the absorption coefficient is also discussed. The result indicates that the doping concentration cannot be too large for the high repetition frequency laser. It has been proved that the high repetition frequency, high laser beam quality, and high average output power of the order of kilowatt of Nd: YAG slab laser can be achieved in this structure.

  20. 1064 nm long-pulsed Nd:YAG laser treatment of basal cell carcinoma.

    Ortiz, Arisa E; Anderson, R Rox; Avram, Mathew M


    Standard surgical and destructive treatments for basal cell carcinoma (BCC) can result in significant morbidity and scarring, stimulating the investigation of alternative non-surgical options. The objective of this study was to determine the safety, clinical, and histological efficacy of pulsed, high-fluence 1064 nm Nd:YAG laser therapy for the treatment of BCC on the trunk and extremities. This was a prospective, non-randomized, open-label clinical trial. Ten subjects with a biopsy-proven BCC less than 1.5 cm in diameter on the trunk or extremities received one treatment with a 10 milliseconds pulsed 1064 nm Nd:YAG laser. Standard excision was performed 1 month after laser treatment to confirm histologic clearance. The laser treatment was quick and well tolerated. There was complete histologic clearance after one treatment in 92% of the BCC tumors, overall. At higher fluences, there was 100% histologic clearance after one treatment. No significant adverse events were seen, including scarring. The 1064 nm long-pulsed Nd:YAG laser may offer a safe alternative for treating BCC off the face. A larger study is highly warranted to confirm these preliminary results. Lasers Surg. Med. 47:106-110, 2015. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  1. Implant Surface Temperature Changes during Er:YAG Laser Irradiation with Different Cooling Systems.

    Monzavi, Abbas; Shahabi, Sima; Fekrazad, Reza; Behruzi, Roohollah; Chiniforush, Nasim


    Peri-implantitis is one of the most common reasons for implant failure. Decontamination of infected implant surfaces can be achieved effectively by laser irradiation; although the associated thermal rise may cause irreversible bone damage and lead to implant loss. Temperature increments of over 10ºC during laser application may suffice for irreversible bone damage. The purpose of this study was to evaluate the temperature increment of implant surface during Er:YAG laser irradiation with different cooling systems. Three implants were placed in a resected block of sheep mandible and irradiated with Er:YAG laser with 3 different cooling systems namely water and air spray, air spray alone and no water or air spray. Temperature changes of the implant surface were monitored during laser irradiation with a K-type thermocouple at the apical area of the fixture. In all 3 groups, the maximum temperature rise was lower than 10°C. Temperature changes were significantly different with different cooling systems used (Plaser with and without refrigeration. Thus, Er:YAG laser irradiation can be a safe method for treatment of periimplantitis.

  2. Use of a microsecond Er:YAG laser in laryngeal surgery reduces collateral thermal injury in comparison to superpulsed CO2 laser.

    Böttcher, Arne; Jowett, Nathan; Kucher, Stanislav; Reimer, Rudolph; Schumacher, Udo; Knecht, Rainald; Wöllmer, Wolfgang; Münscher, Adrian; Dalchow, Carsten V


    Despite causing significant thermocoagulative insult, use of the carbon dioxide (CO2) laser is considered gold standard in surgery for early stage larynx carcinoma. Limited attention has been paid to the use of the erbium:yttrium-aluminium-garnet (Er:YAG) laser in laryngeal surgery as a means to reduce thermal tissue injury. The objective of this study is to compare the extent of thermal injury and precision of vocal fold incisions made using microsecond Er:YAG and superpulsed CO2 lasers. In the optics laboratory ex vivo porcine vocal folds were incised using Er:YAG and CO2 lasers. Lateral epithelial and subepithelial thermal damage zones and cutting gap widths were histologically determined. Environmental scanning electron microscopy (ESEM) images were examined for signs of carbonization. Temperature rise during Er:YAG laser incisions was determined using infrared thermography (IRT). In comparison to the CO2 laser, Er:YAG laser incisions showed significantly decreased epithelial (236.44 μm) and subepithelial (72.91 μm) damage zones (p CO2 (878.72 μm) compared to Er:YAG (1090.78 μm; p = 0.027) laser. ESEM revealed intact collagen fibres along Er:YAG laser cutting edges without obvious carbonization, in comparison to diffuse carbonization and tissue melting seen for CO2 laser incisions. IRT demonstrated absolute temperature rise below 70 °C for Er:YAG laser incisions. This study has demonstrated significantly reduced lateral thermal damage zones with wider basal cutting gaps for vocal fold incisions made using Er:YAG laser in comparison to those made using CO2 laser.

  3. Characterization and laser performance of a new material: 2 at. % Nd:YAG grown by the Czochralski method.

    L'huillier, Johannes A; Bitz, Gunter; Wesemann, Volker; von Loewis of Menar, Patric; Wallenstein, Richard; Borsutzky, Annette; Ackermann, Lothar; Dupré, Klaus; Rytz, Daniel; Vernay, Sophie


    We report on the optical quality and laser performance of Czochralski-grown 2-at. %-doped Nd:YAG. Using a diode pumped laser in an end pumped configuration, we compare the laser performance of this material with the performance of 1-at. %-doped Nd:YAG and 0.7-at. %-doped Nd:YVO4 crystals. Experimental results show the superior performance of 2-at. % Nd:YAG over Nd:YVO4. With a pump power of 25.7 W, a maximum output power of 12.3 W with a slope efficiency of 57% and an optical-to-optical efficiency of 48% were achieved.

  4. Evaluation of the Effectiveness of Nd: YAG Laser under Urethroscope in the Treatment of Intraurethral Condyloma Acuminata (CA) in Males

    赵冬; 曾伟宏; 翟胜


    Objective: To evaluate the therapeutic effect of Nd:YAG laser under urethroscope for the treatment of intraurethral Candyloma Acuminata (CA) in males.Method: Nd:YAG laser under urethroscope was employed to remove the warts.Result: Seventeen patients out of eighteen cases with CA were cured after the first procedure. The ure rate was 94.4%.For second treatment, the cure rate was 100% and no relapse occurred after observation for 12 - 4 months.Conclusion: Nd:YAG laser by urethroscope is a very good method for the treatment of intraurethral CA.

  5. The measurement of capillary waves on a weldpool formed by a Nd:YAG laser

    Deam, R T; Harris, J


    Experiments were performed using an on-line pyrometer to measure the capillary waves on a weldpool formed by a Nd: YAG laser. The surface temperature measurements taken from the weldpool revealed strong temporal fluctuations. Fourier transform of the pyrometer data revealed distinct peaks, consistent with calculated resonant frequencies for capillary surface waves on the weldpool formed by the laser. The possibility of using on-line measurement of surface temperature fluctuations to control weldpool depth in laser welds is discussed. The work forms part of an on-going programme to develop closed loop control for laser processing at Swinburne University

  6. [Moist ablation of the corneal surface with the Er:YAG laser. Results of optimizing ablation].

    Bende, T; Jean, B; Matallana, M; Seiler, T; Steiner, R


    The Er:YAG laser, emitting light at 2.94 microns, may be an alternative to the 193 nm excimer laser for photorefractive keratectomy. Compared to the excimer laser, the ablation rate is very high. Surface roughness is also more pronounced than for the excimer laser. Using a precorneal liquid film, these two factors can be reduced, as shown in ablation experiments performed on porcine corneas. Thermal damage of the remaining corneal tissue is another side effect. There is no significant decrease in the amount of thermal damage with this new technique,--not even when the pulse length is reduced.

  7. Scale invariance and scaling law of Thomson backscatter spectra by electron moving in laser-magnetic resonance regime

    Fu, Yi-Jia; Wan, Feng; Sang, Hai-Bo; Xie, Bai-Song


    The Thomson scattering spectra by an electron moving in the laser-magnetic resonance acceleration regime are computed numerically and analytically. The dependence of fundamental frequency on the laser intensity and magnetic resonance parameter is examined carefully. By calculating the emission of a single electron in a circularly polarized plane-wave laser field and constant external magnetic field, the scale invariance of the radiation spectra is evident in terms of harmonic orders. The scaling law of backscattered spectra are exhibited remarkably for the laser intensity as well for the initial axial momentum of the electron when the cyclotron frequency of the electron approaches the laser frequency. The results indicate that the magnetic resonance parameter plays an important role on the strength of emission. And the rich features of scattering spectra found may be applicable to the radiation source tunability.

  8. Thomson scattering laser-electron X-ray source for reduction of patient radiation dose in interventional coronary angiography

    Artyukov, I. A.; Dyachkov, N. V.; Feshchenko, R. M.; Polunina, A. V.; Popov, N. L.; Shvedunov, V. I.; Vinogradov, A. V.


    It was medical applications that stimulated F. Carrol in the early 1990s to start the research of on relativistic Thomson scattering X-ray sources, as a part of the infrastructure of the future society. The possibility to use such a source in interventional cardiology is discussed in this paper. The replacement of X-ray tube by relativistic Thomson scattering Xray source is predicted to lower the patient radiation dose by a factor of 3 while image quality remains the same. The required general characteristics of accelerator and laser units are found. They can be reached by existing technology. A semiempirical method for simulation of medical and technical parameters of interventional coronary angiography systems is suggested.

  9. Novel technique to treat melasma in Chinese: The combination of 2940-nm fractional Er:YAG and 1064-nm Q-switched Nd:YAG laser.

    Tian, Wei Cheng Brian Anthony


    Melasma is one of the most common pigmented lesions in Chinese women. Although topical therapies are the mainstay treatment, lasers are being used increasingly to treat pigmented lesions. Laser treatment of melasma is however still controversial. This is because lasers have not been able to produce complete clearance of melasma and recurrence rates are high. Laser treatments also cause complications such as hypopigmentation and post-inflammatory hyperpigmentation. In this article, we report on a novel technique using a combination of fractional 2940-nm Er:YAG and 1064-nm Q-switched Nd:YAG lasers. We achieved a rapid improvement in two cases of melasma in Chinese type III skin. The improvement was seen rapidly within a month of treatment. Follow-up at 6 months showed sustained results with no complications. This novel technique is able to safely confer excellent and sustained clearance within a short treatment time.

  10. Effects of Nd:YAG laser irradiation on the hybrid layer of different adhesive systems.

    Ferreira, Leila S; Ferreira, Lisiane Soares; Francci, Carlos; Navarro, Ricardo Scarparo; Calheiros, Fernanda Calabró; Eduardo, Carlos de Paula


    The aim of this in vitro study was to evaluate the microtensile bond strength (microTBS) and hybrid layer morphology of different adhesive systems, either followed by treatment with Nd:YAG laser irradiation or not. Previous studies have shown the effects of Nd:YAG laser irradiation on the dentin surface at restoration margins, but there are few reports about the significance of the irradiation on the hybrid layer. The flattened coronal and root dentin samples of 24 bovine teeth were randomly divided into 8 groups, according to the adhesive system used -- Scotchbond Multi Purpose (SBMP) or Clearfil SE Bond (CSEB) -- and were either irradiated with Nd:YAG or not, with different parameters: 0.8 W/10 Hz, 0.8 W/20 Hz, 1.2 W/10 Hz, 1.2 W/20 Hz. The left sides of specimens were the control groups, and right sides were irradiated. A composite crown was built over bonded surfaces and stored in water (24 h at 37 degrees C). Specimens were sectioned vertically into slabs that were subjected to microTBS testing and observed by SEM. Control groups (27.81 +/- 1.38) showed statistically higher values than lased groups (21.37 +/- 0.99), and CSEB control group values (31.26 +/- 15.71) were statistically higher than those of SBMP (24.3 +/- 10.66). There were no significant differences between CSEB (20.34 +/- 10.01) and SBMP (22.43 +/- 9.82) lased groups. Among parameters tested, 0.8 W/10 Hz showed the highest value (25.54 +/- 11.74). Nd:YAG laser irradiation caused dentin to melt under the adhesive layer of both adhesive systems tested. With the parameters used in this study, Nd:YAG laser irradiation of the hybrid layer promoted morphological changes in dentin and negatively influenced the bond strength of both adhesive systems.

  11. Effect of Fluoride Varnish Combined with Er:YAG Laser on the Permeability of Eroded Dentin: An In Situ Study.

    Nemezio, Mariana Alencar; Carvalho, Sandra Chiga; Scatolin, Renata Siqueira; Colucci, Vivian; Galo, Rodrigo; Corona, Silmara Aparecida Milori


    This study evaluated the combined effect of fluoride varnish and Er:YAG laser on the permeability of eroded bovine root dentin. After initial erosive challenge followed by a remineralization period, the specimens were divided in two groups according to the treatment - fluoride varnish and non-fluoride varnish - and were subdivided according to the irradiation protocol: Er:YAG laser (100 mJ, 3 Hz, 12.8 J/cm2per pulse, non-contact and defocus mode) and non-irradiated. After a lead-in period, 7 volunteers wore a palatal device containing 4 specimens that were subjected to erosive challenges. At the first experimental phase, 4 volunteers used specimens treated with fluoride varnish and fluoride varnish+Er:YAG laser and 3 volunteers used specimens treated with non-fluoride varnish and non-fluoride varnish+Er:YAG laser. After a washout period, volunteers were crossed to treatments, characterizing a 2x2 crossover experiment. At the end of the experimental phase, the quantitative response variable was obtained by permeability analysis and the qualitative response by scanning electron microscopy (SEM). Two-way ANOVA and Tukey-Kramer's test revealed that specimens treated with fluoride varnish+Er:YAG laser showed the lowest permeability and a significant difference was found between this group and the others. When varnish (fluoride/non-fluoride) was applied in the absence of Er:YAG laser, higher permeability was found when compared to the laser-treated groups. SEM evaluations showed partially or completely obliterated dentinal tubules when specimens were treated with fluoride varnish+Er:YAG laser. It may be concluded that Er:YAG laser was able to control the permeability of eroded root dentin and the combination with fluoride varnish increased laser action.

  12. A comparison of diode laser and Er:YAG lasers in the treatment of gingival melanin pigmentation.

    Simşek Kaya, Göksel; Yapici Yavuz, Günay; Sümbüllü, Muhammed A; Dayi, Ertunç


    This study compared the use of diode and Er:YAG lasers in treating gingival melanin pigmentation (GMP) in terms of gingival depigmentation, local anesthesia requirements, postoperative pain/discomfort, depigmentation effectiveness, and total treatment duration. Twenty patients (13 female, 7 male) referred with GMP were enrolled in the study. Patients were randomly divided into 2 groups. Group 1 was treated with a gallium aluminum arsenide diode laser with a continuous wavelength of 808 nm, and group 2 was treated with an Er:YAG laser with a continuous wavelength of 2,940 nm. Gingival depigmentation was performed by applying the laser at 1 W. Treatment was administered on a weekly basis until a normal pink gingival color was observable in clinical examination and photographs. In addition, patients were asked to evaluate the procedure by using a self-administered questionnaire. Procedures were carried out without the need for any topical or local anesthetic, and no unpleasant events occurred during the actual procedure or the healing period. The total length of treatment was significantly shorter with the diode laser (group 1) than with the Er:YAG laser (group 2; P lasers administered at 1 W both result in satisfactory depigmentation of GMP. Copyright © 2012 Elsevier Inc. All rights reserved.

  13. Treatment of nevus of OTA by Q-switched, frequency doubled, ND: Yag laser

    National Skin and Hair Care Centre


    Full Text Available Nevus of Ota is a dermal melanocytic nevus for which hitherto no effective therapy was available. Lasers have been successfully tried for ablation. But there is no Indian experience till date. Q- Switched, Frequency Doubled, Nd: YAG Laser was installed at our centre an year ago. The first operated case, which has shown near complete pigment dilution, is being presented. The patient underwent three treatments with a minimum of 2 months between sessions. Pre and post therapy photographs were taken and side effects documented. The patient has shown near complete pigment dilution after 3 treatments. Q-Switched, Frequency Doubled, Nd: YAG Laser is effective in treating Nevus of Ota in the Indian skin types. There are no complications noticed till date in our experience.

  14. Soft-tissue applications of the holmium:YAG laser in urology

    Denstedt, John D.; Razvi, Hassan A.; Chun, Samuel S.; Sales, Jack L.


    The ideal surgical laser for the treatment of soft tissue pathology should possess both ablative and hemostatic abilities. As well, for use in urologic conditions the laser must also be suitable for endoscopic use. The Holmium:YAG laser possesses these qualities and in preliminary clinical use has demonstrated a variety of potential urologic applications. In this study we review our initial experience with the Holmium:YAG laser over a 18 month period. A total of 51 patients underwent 53 procedures for a variety of soft tissue conditions including: bladder tumor ablation (25), incision of ureteral stricture (15), incision of urethral stricture (6), treatment of ureteropelvic junction obstruction (3), incision of bladder neck contracture (2), and ablation of a ureteral tumor (2). Satisfactory hemostasis was achieved in all cases. Procedures were considered successful (no further intervention being required to treat the condition) in 81% of the cases. Two patients with dense bladder neck contractures required electroincision under the same anesthetic for completion of the procedure. A single complication, that of urinary extravasation following incision of a urethral stricture resolved with conservative management. In summary, the Holmium:YAG laser has demonstrated safety and proficiency in the treatment of a variety of urologic soft tissue conditions.

  15. Novel pressure sensor by diode-pumped birefringent Nd:YAG dual-frequency laser

    Huang, Chunning; Li, Yan; Zhang, Shulian; Guo, Hui


    The prototype of a novel sensor based on laser frequency splitting technology is presented in this paper and the results of a series of experiments are reported. A scheme of the novel pressure sensor by diode-pumped birefringent Nd:YAG dual-frequency laser is brought forward. As a result of the stress birefringence the laser's longitudinal mode is split to two with frequency difference. Both the theoretical analysis and the experiments indicate that there is a direct ratio relation between the frequency difference and the pressure imposed on the Nd:YAG crystal. Therefore when the external pressure is sensed by the Nd:YAG dual-frequency laser and the beat frequency is measured by the frequency counter, the pressure value can be obtained from the magnitude of the beat frequency. The laser can operate under single mode or complex modes with little error to the experiment results. Some research work under different pumping ways is finished and it indicates that the beat frequency has little relation with pumping ways. The experiment has a good linearity (R greater than 0.999) with satisfied precision, sensitivity (5.27 MHz/kPa) and stability, which provides a good academic and experimental foundation for further research.

  16. Effectiveness of an Er:YAG laser in etching the enamel surface for orthodontic bracket retention.

    Kim, Jung-Ho; Kwon, Oh-Won; Kim, Hyung-Il; Kwon, Yong Hoon


    The purpose of this study was to test the effectiveness of an Er:YAG laser in etching the enamel surface for orthodontic treatment. Bovine incisors were either acid-etched or laser-treated. An orthodontic bracket was attached on each treated surface using one-step dentin adhesive and self-curing resin. Tensile bond strength was then evaluated. In addition, the surface morphology of specimens treated with phosphoric acid/laser and self-etching primer, as well as the cross-section of enamel-primer-resin interfaces, were observed. One-Up Bond F-treated specimens after Er:YAG laser ablation showed statistically similar tensile bond strength (9.9 +/- 1.3 MPa) to that of phosphoric acid-etched specimens (11.8 +/- 1.7 MPa). Surface roughness and thickness of the enamel-primer-resin interfaces did not much affect the tensile bond strength of the tested specimens. In conclusion, Er:YAG laser ablation achieved clinically acceptable level of tensile bond strength when used with One-Up Bond F.

  17. Synthesis and Modeling of Temperature Distribution For Nanoparticles Produced Using Nd:YAG Lasers

    Mu’ataz S. Hassan


    Full Text Available Nanosecond pulses of Nd:YAG laser were employed to produce silver and silicon nanoparticles by laser ablation process in liquid. Two Nd:YAG laser systems of 6 and 10 nanoseconds pulse duration with variable laser energy in the range 700–760 mJ were employed. Morphological investigation using AFM and TEM reveals the formation of silver and silicon nanoparticles with uniform size distribution. It is found that mean nanoparticles sizes of 50 and 70 nm for silver and silicon, respectively, are produced under similar laser parameters. Moreover, theoretical model was used to estimate the temperature distributions for both silver and silicon nanoparticles. It is also found that the maximum temperature of about 50 k K° and 70 k K° for silver and silicon nanoparticles, respectively, is generated when Nd:YAG of 10 ns is used to prepare nanoparticles. Zeta potential measurements reveal that silver nanoparticles are more stable than those of silicon prepared by similar conditions.

  18. Nd:YAG laser-induced hyperthermia treatment of spontaneously occurring veterinary head and neck tumors.

    Panjehpour, M; Overholt, B F; Frazier, D L; Klebanow, E R


    Conventional hyperthermia treatment of superficial tumors in the oral cavity is troublesome due to difficulty in accessing the lesion. A new hyperthermia technique employing near-infrared radiation delivered through a flexible silica optical fiber is described. The system consisted of an Nd:YAG laser for tissue heating, a He-Ne laser for aiming beam, a computer-controlled optical shutter, an interstitial thermometer, computer, and a printer. A 3-m-long 600-microns silica fiber delivered laser energy to the tumor via surface illumination. Using the aiming beam, the spot size was adjusted to include 5 mm of surrounding normal tissue. A thermocouple implanted in the tumor base provided temperature feedback to maintain desired hyperthermic temperature within the lesion. Three spontaneously occurring canine (two squamous cell carcinomas on the gum, one pigmented melanoma on the hard palate) and one feline tumor (squamous cell carcinoma on the nose) have been treated with Nd:YAG laser hyperthermia. Hyperthermia was delivered at 43.5 degrees C for 1 h. All animals received standard radiation treatment prior to hyperthermia. Nd:YAG laser hyperthermia allowed effective and efficient delivery of heat to veterinary nasal and oral lesions otherwise not treatable with conventional heating techniques.

  19. Impact of pulse duration on Ho:YAG laser lithotripsy: fragmentation and dusting performance.

    Bader, Markus J; Pongratz, Thomas; Khoder, Wael; Stief, Christian G; Herrmann, Thomas; Nagele, Udo; Sroka, Ronald


    In vitro investigations of Ho:YAG laser-induced stone fragmentation were performed to identify potential impacts of different pulse durations on stone fragmentation characteristics. A Ho:YAG laser system (Swiss LaserClast, EMS S.A., Nyon, Switzerland) with selectable long or short pulse mode was tested with regard to its fragmentation and laser hardware compatibility properties. The pulse duration is depending on the specific laser parameters. Fragmentation tests (hand-held, hands-free, single-pulse-induced crater) on artificial BEGO stones were performed under reproducible experimental conditions (fibre sizes: 365 and 200 µm; laser settings: 10 W through combinations of 0.5, 1, 2 J/pulse and 20, 10, 5 Hz, respectively). Differences in fragmentation rates between the two pulse duration regimes were detected with statistical significance for defined settings. Hand-held and motivated Ho:YAG laser-assisted fragmentation of BEGO stones showed no significant difference between short pulse mode and long pulse mode, neither in fragmentation rates nor in number of fragments and fragment sizes. Similarly, the results of the hands-free fragmentation tests (with and without anti-repulsion device) showed no statistical differences between long pulse and short pulse modes. The study showed that fragmentation rates for long and short pulse durations at identical power settings remain at a comparable level. Longer holmium laser pulse duration reduces stone pushback. Therefore, longer laser pulses may result in better clinical outcome of laser lithotripsy and more convenient handling during clinical use without compromising fragmentation effectiveness.

  20. Analysis of apical sealing of canals irradiated with Er: YAG and Nd: YAG lasers and filled with AH Plus®

    Celso Luis Caldeira


    Full Text Available Introduction: Laser technology is gaining increasing importance in dental practice and also in the field of Endodontics with its ability to promote disinfection and experimentally in the preparation of root canal. The action of different types of lasers results in changes representing the increase in permeability of dentinal tissue (Er: YAG or sometimes by a decrease in melting and recrystallization of dentin (Nd: YAG. Objective: this study assessed through apical dye leakage, the influence of irradiation with two types of laser, regarding to the quality of apical sealing of endodontic fillings. Material and methods: Thirty-six single-rooted teeth were used after being prepared with the ProFile system up to size #40 instrument and then divided into four experimental and two control groups. The technique used previously to the filling was as follows: G1 – not irradiated; G2 – irradiated with Er: YAG; G3 – irradiated with Nd: YAG and G4 – irradiated with Er: YAG followed by Nd: YAG. After external waterproofing and dry, the specimens were filled with a cold vertical condensation technique, using AH Plus sealer, and immediately immersed into 0.5% methylene blue solution for subsequent cleavage. The linear values of apical marginal leakage were obtained with the aid of an optical microscope connected to a computer using the Image Lab® software. Results: Data analysis showed the non-existence of statistically significant (p = 0.05 differences between different groups. Conclusion: It was concluded that the laser does not have influence on the apical sealing.

  1. Combined application of Er:YAG and Nd:YAG lasers in treatment of chronic periodontitis. A split-mouth, single-blind, randomized controlled trial.

    Sağlam, M; Köseoğlu, S; Taşdemir, I; Erbak Yılmaz, H; Savran, L; Sütçü, R


    The aim of the present study was to compare the effectiveness of combined Er:YAG and Nd:YAG laser therapy to that of scaling and root planing with hand instruments in non-surgical treatment of chronic periodontitis. Twenty-five systemically healthy patients with chronic periodontitis were selected for this study. The quadrants were randomly allocated in a split-mouth design to either combined Er:YAG (160 mJ/pulse, 10 Hz) and Nd:YAG laser (100 mJ/pulse, 20 Hz) therapy (test group) or scaling and root planing alone (control group). At baseline, 1 month and 3 months after treatment, plaque index, gingival index, probing depth, clinical attachment level and bleeding on probing (%), were recorded and gingival crevicular fluid and subgingival plaque samples were taken. The gingival crevicular fluid levels of interleukin-1β and tumor necrosis factor-α were analyzed by enzyme-linked immunosorbent assay. Quantitative analysis of red complex bacteria was performed using quantitative real-time polymerase chain reaction. The clinical parameters had significantly improved for both groups after treatment. There were statistically significant differences in probing depth and clinical attachment level between the test and control groups only for deep pockets (≥7 mm) (Pnd microbiological parameters at any time points (P>.05). The present study suggests that a combined course of Er:YAG and Nd:YAG laser therapy may be beneficial particularly in inaccessible areas such as deep pockets on a short-term basis. Further, well-designed studies are required to assess the effectiveness of the combination of these lasers. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  2. Nd:YAG laser in endodontics: filling-material edge bordering on a root channel laser cavity

    Belikov, Andrei V.; Sinelnik, Yuri A.; Moroz, Boris T.; Pavlovskaya, Irina V.


    For the very first time it is represented a study of filling material edge bordering upon root channel cavity modified with a laser. As a filling material it is used a glass ionomer cement. It is demonstrated that Nd:YAG laser radiation effects on increase of grade of edge bordering on the average of 20 - 30% at temperature rise of no more than 2 - 3 degrees in periodontium area in a period of operation.

  3. Comparative study of excimer and erbium:YAG lasers for ablation of structural components of the knee

    Vari, Sandor G.; Shi, Wei-Qiang; van der Veen, Maurits J.; Fishbein, Michael C.; Miller, J. M.; Papaioannou, Thanassis; Grundfest, Warren S.


    This study was designed to compare the efficiency and thermal effect of a 135 ns pulsed-stretched XeCl excimer laser (308 nm) and a free-running Erbium:YAG laser (2940 nm) with 200 microsecond(s) pulse duration for ablation of knee joint structures (hyaline and fibrous cartilage, tendon and bone). The radiant exposure used for tissue ablation ranged from 2 to 15 J/cm2 for the XeCl excimer and from 33 to 120 J/cm2 for Er:YAG. The excimer and Er:YAG lasers were operated at 4 and 5 Hz respectively. The ablative laser energy was delivered to tissue through fibers. Ablation rates of soft tissues (hyaline and fibrous cartilage, tendon) varied from 8.5 to 203 micrometers /pulse for excimer and from 8.2 to 273 micrometers /pulse for Er:YAG lasers. Ablation rates of soft tissues are linearly dependent on the radiant exposure. Within the range of parameters tested all the tissues except the bone could be rapidly ablated by both lasers. Bone ablation was much less efficient, requiring 15 J/cm2 and 110 J/cm2 radiant exposure for excimer and Er:YAG lasers to ablate 9.5 and 8.2 micrometers tissue per pulse. However, excimer laser ablation produced less thermal damage in the tissues studied compared to Er:YAG at the same laser parameters. The authors conclude that both lasers are capable of efficient knee joint tissue ablation. XeCl excimer laser requires an order of magnitude less energy than Er:YAG laser for comparable tissue ablation.

  4. Spatially resolved Thomson scattering measurements of the transition from the collective to the non-collective regime in a laser-produced plasma

    Schaeffer, D. B.; Constantin, C. G.; Bondarenko, A. S.; Everson, E. T.; Niemann, C.


    We present optical Thomson scattering results that image for the first time in a single measurement the spatial transition from collective to non-collective scattering. Data were taken in the Phoenix laser laboratory at the University of California, Los Angeles. The Raptor laser was used to ablate a carbon plasma, which was diagnosed with the frequency-doubled Phoenix laser serving as a Thomson scattering probe. Scattered light was collected from the laser plasma up to 10 cm from the target surface and up to 10 us after ablation, and imaged with high spatial and spectral resolutions. The results show a strong Thomson collective feature close to the target surface that smoothly transitions to a non-collective feature over several mm.

  5. Treatment of peri-implantitis around TiUnite-surface implants using Er:YAG laser microexplosions.

    Yamamoto, Atsuhikp; Tanabe, Toshiichiro


    Implant therapy can lead to peri-implantitis, and none of the methods used to treat this inflammatory response have been predictably effective. It is nearly impossible to treat infected surfaces such as TiUnite (a titanium oxide layer) that promote osteoinduction, but finding an effective way to do so is essential. Experiments were conducted to determine the optimum irradiation power for stripping away the contaminated titanium oxide layer with Er:YAG laser irradiation, the degree of implant heating as a result of Er:YAG laser irradiation, and whether osseointegration was possible after Er:YAG laser microexplosions were used to strip a layer from the surface of implants placed in beagle dogs. The Er:YAG laser was effective at removing an even layer of titanium oxide, and the use of water spray limited heating of the irradiated implant, thus protecting the surrounding bone tissue from heat damage.

  6. Role of surface tension and roughness on the wettability of Er:YAG laser irradiated dentin: In vitro study


    Introduction: The aim of this “in vitro” study was to evaluate the role of surface tension and surface roughness in the wettability, considered essential for a good adhesion, comparing Er:YAG laser - to bur-prepared dentin.

  7. Advantages of fulguration of posterior urethral valves by Nd: YAG laser

    D K Gupta


    Full Text Available Posterior Urethral Valves (PUV are one of the com-monest urolgical problems seen in children and the electro-coagulation, which is the most widely preferred modality to ablate the valves, may not be feasible in small-for-date and low-birth-weight neonates as the suitable size resec-toscope/cystoscope may not available. With the availa-bility of Nd: YAG laser at our institute recently, we started performing the laser fulguration instead of electrocoagu-lation of the valves. We reviewed our experience with the emerging role of the Nd: YAG laser in the fulguration of PUV, comparing the results with a historical control group who underwent the classical electrocoagulation of the PUV. The boys (n=50 diagnosed to have PUV by VCUG were confirmed by Wolf 8.5 size cystoscope, underwent Nd: YAG laser fulguration of the valves with a bare fiber, as a day-care procedure without postoperative catheteri-zation. Historical controls (n=50 who had undergone classical electrocoagulation using 9.5 size Wolf resectos-cope served as the controls. The mean age was 1.3 y and 2.6 y in laser and electrocoagulation group respectively. The mean hospital stay of the electrocoagulation group was 3.8 d. Three patients after electrocoagulation devel-oped hematuria and 4 required refulguration whereas in the laser group 5 required refulguration and none devel-oped hematuria. In conclusion, endoscopic laser fulgura-tion of PUV is technically feasible even in neonates and small children. Laser offers excellent results that are com-parable to the time-honored electrocoagulation procedure. This has the additional advantage forfulgurating the PUV in smaller caliber urethra as this can be performed with the smaller available cystoscope that has a side channel, admitting the laser fiber.

  8. Enamel surface roughness and dental pulp response to coaxial carbon dioxide-neodymium: YAG laser irradiation.

    Arcoria, C J; Steele, R E; Wagner, M J; Judy, M M; Matthews, J L; Hults, D F


    The purpose of this study was to evaluate the effect of a coaxial carbon dioxide/neodymium:yttrium aluminium garnet laser beam on enamel surface roughness and the dental pulps of mongrel dogs. In four dogs, four maxillary left posterior teeth were irradiated at 16 cm source-tooth distances. Two teeth were irradiated with 16 W CO2/16 W Nd:YAG and the remaining two with 16 W CO2/40 W Nd:YAG. Two maxillary right teeth were untreated controls. In addition, mandibular premolars were irradiated at the same distance and power levels, extracted, and analysed for surface roughness. Significant differences in surface roughness were found between control samples and either power level, but not between enamel surfaces at the two power levels. Maxillary teeth were removed at 10 days postoperatively, sectioned and stained (H & E). The reaction of pulpal cells to irradiation was scored. Data analysis revealed statistically significant differences between the control and lower power Nd:YAG groups and between the control and higher power Nd:YAG groups. The difference in pulpal response between both laser groups approached significance.

  9. Er:YAG Laser: A New Technical Approach to Remove Torus Palatinus and Torus Mandibularis

    J. P. Rocca


    Full Text Available Objective. The aim of this study was to assess the ability of Er:YAG laser to remove by excision torus mandibularis and to smooth torus palatinus exostosis. Materials and Methods. Torus mandibularis (TM and torus palatinus (TP were surgically eliminated via the Er:YAG laser using the following parameters: TM: output power ranging from 500 to 1000 mJ, frequency from 20 to 30 Hz, sapphire tips (diameter 0.8 mm, air-water spray (ratio 5/5, pulse duration 150 μsec, fluence ranging from 99592 J/cm2 to 199044,586 J/cm2. TP: a peeling technique was used to eliminate TP, as excision by slicing being impossible here. Results. TM: excision was obtained after 12730 pulses. TP: smoothing technique took more time compared with excision. Once peeling was considered to be accomplished, the use of a surgical rasp was necessary to eliminate bone spicules that could delay the wound to heal in good conditions. Conclusion. Er:YAG excision (TM or Er:YAG peeling (TP are safe clinical techniques easy to practice even if the time required for excision or surface smoothing is more than the time required with bony burs and high speed instruments.

  10. Er:YAG Laser: A New Technical Approach to Remove Torus Palatinus and Torus Mandibularis

    Rocca, J. P.; Raybaud, H.; Merigo, E.; Vescovi, P.; Fornaini, C.


    Objective. The aim of this study was to assess the ability of Er:YAG laser to remove by excision torus mandibularis and to smooth torus palatinus exostosis. Materials and Methods. Torus mandibularis (TM) and torus palatinus (TP) were surgically eliminated via the Er:YAG laser using the following parameters: TM: output power ranging from 500 to 1000 mJ, frequency from 20 to 30 Hz, sapphire tips (diameter 0.8 mm), air-water spray (ratio 5/5), pulse duration 150 μsec, fluence ranging from 99592 J/cm2 to 199044,586 J/cm2. TP: a peeling technique was used to eliminate TP, as excision by slicing being impossible here. Results. TM: excision was obtained after 12730 pulses. TP: smoothing technique took more time compared with excision. Once peeling was considered to be accomplished, the use of a surgical rasp was necessary to eliminate bone spicules that could delay the wound to heal in good conditions. Conclusion. Er:YAG excision (TM) or Er:YAG peeling (TP) are safe clinical techniques easy to practice even if the time required for excision or surface smoothing is more than the time required with bony burs and high speed instruments. PMID:22792500

  11. Fabrication, optical properties and laser outputs of Nd:YAG ceramics based on laser ablated and pre-calcined powders

    Osipov, V. V.; Maksimov, R. N.; Shitov, V. A.; Lukyashin, K. E.; Toci, G.; Vannini, M.; Ciofini, M.; Lapucci, A.


    Transparent Nd:YAG ceramic was fabricated by the solid-state reaction method with an additional round of pre-calcining using nanopowders of 1 at.% Nd:Y2O3 and Al2O3 synthesized by laser ablation. The pre-calcining step and addition of tetraethyl orthosilicate was found crucial for fabricating high optical quality Nd:YAG ceramic from such nanoparticles. The transmittance of the obtained 2-mm-thick Nd:YAG ceramic was 83.6% at the wavelength of 1064 nm, which is very close to the theoretical value. The uniformity of the optical quality of ceramic was mapped by analyzing the point-by-point transmission of a focused laser beam. The average volume of the scattering centers in the obtained ceramic was evaluated by direct count method to be 17 ppm. The Nd distribution was determined by fluorescence imaging to be homogeneous throughout the sample. Output power of 4.9 W with a slope efficiency of 52.7% was obtained in 1.5-mm-thick Nd:YAG ceramic under a quasi-continuous wave (QCW) laser diode end pumping at 805 nm.

  12. 1.06-μm Nd:YAG laser coagulation tonsillectomy: an animal study

    Wang, Zhi; Pankratov, Michail M.; Volk, Mark S.; Perrault, Donald F., Jr.; Shapshay, Stanley M.


    Tonsillectomy is one of the most frequently performed surgeries which is not free from post- operative morbidity. We have developed a non contact photocoagulation technique using 1.06 micrometers Nd:YAG laser and tested its safety and efficacy in an animal model. Eight animals were divided into the laser coagulation group (6 animals) and the laser excision group (2 animals). Tonsils of the laser coagulation animals were irradiated with 8 - 10 W of laser power for 5 - 6 min in a slow painting-like motion over the surface of a tonsil until slight blanching of mucosa was noticed. Tonsils of the laser excision group were resected with 25 - 30 W of 1.06 micrometers Nd:YAG laser power through a contact fiber. The animals were examined endoscopically at 1.5 hrs and at 2, 5, 12, 30, and 42 days post treatment. Atrophic process was followed until total disappearance of tonsillar tissue was observed. The animals were sacrificed at various time intervals and the tonsillar specimens were collected for gross and histological examination. The thermal damage to mucosa and adjacent tissues was minimal which we attribute to a low laser power and cooling from preoperative injection of saline into subcapsular space. The potential advantages of this technique include intact mucosa with no intra- or post-operative bleeding, less pain, and avoidance of general anesthesia. These advantages may enable this surgery to become an in-the-office procedure.

  13. Influence of Nd:YAG or Er:YAG laser surface treatment on microtensile bond strength of indirect resin composites to resin cement. Lasers surface treatment of indirect resin composites.

    Caneppele, T M F; de Souza, A C Oliveira; Batista, G R; Borges, A B; Torres, C R G


    This study evaluated the influence of the surface pretreatment of indirect resin composite (Signum, Admira Lab and Sinfony) on the microtensile bond strength of a resin cement. Sixty samples made of each brand were divided into 6 groups, according to surface treatment: (1) control; (2) controlled-air abrasion with Al2O3; (3) Er:YAG Laser 200 mJ, 10 Hz, for 10s; (4) Er: YAG Laser 300 mJ, 10 Hz, for 10 s; (5) Nd:YAG 80 mJ, S15Hz for 1 min; (6) Nd:YAG 120mJ, 15 Hz for 1 min. After treatments, all the groups received an application of 37% phosphoric acid and adhesive. The pair of blocks of the same brand were cemented to each other with dual resin cement. The blocks were sectioned to obtain resin-resin sticks (1 x1 mm) and analyzed by microtensile bond testing. The bond strength values were statistically different, irrespective of the surface treatment performed, with highest values for Sinfony (43.81 MPa) and lowest values for Signum (32.33 MPA). The groups treated with the Nd:YAG laser showed the lowest bond strength values and power did not interfere in the results, both for Nd:YAG laser and Er:YAG. Controlled-air abrasion with Al203 is an efficient surface treatment method and the use of the Nd:YAG and Er:YAG lasers reduced bond strength, irrespective of the intensity of energy used.

  14. Nd:YAG Ceramic ThinZag (registered trademark) High-Power Laser Development


    CHAPTER 9 Nd:YAG Ceramic ThinZag® High-Power Laser Development Daniel E. Klimek Principal Research Scientist, Textron Defense Systems, Wilmington...ThinZag High-Power Laser Development 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER...Power Laser Development N d : Y A G C e r a m i c T h i n Z a g ® H i g h - P o w e r L a s e r D e v e l o p m e n t 209 over the years at

  15. Impulse transfer to the surface of aluminum and copper from a pulsed Nd: YAG laser

    Xu, Bingzhang; Wang, Qingpu; Zhang, Xingyu; Zhao, Shenzi; Xia, Yueyuan; Mei, Liangmo; Wang, Xiangtai; Wang, Gongtong


    Impulse coupling coefficients in air from 1.06 μm, 10 ns, Nd: YAG pulsed-laser radiation to aluminum and copper targets are measured using the ballistic pendulum method in the laser power-density range from 2.0×108 W/cm2 to 4.0×109 W/cm2. A modified laser-supported detonation (LSD) wave and cylindrical blast wave theory incorporating the vaporization model is proposed to calculate the impulse coupling coefficients. It is found that the theoretical results obtained with the modified model agree well with the experimental data.

  16. Bleb failure and intraocular pressure rise following Nd: Yag laser capsulotomy.

    Diagourtas, Andreas; Petrou, Petros; Georgalas, Ilias; Oikonomakis, Kostantinos; Giannakouras, Panagiotis; Vergados, Athanasios; Papaconstantinou, Dimitrios


    To report the negative effect of Nd: Yag (Neodymium-doped: Yttrium Aluminium Garnet) laser capsulotomy on the intraocular pressure (IOP) and the trabeculectomy bleb integrity, in a small series of eyes, both trabeculectomised and pseudophakic, following the laser application for the management of posterior capsular opacification (PCO). This is a retrospective, non-comparative interventional case series study, in which 20 trabeculectomised and pseudophakic eyes from 15 patients, with otherwise well functioning blebs, were presented with uncontrolled IOP, in a variable distance of time following the application of YAG laser capsulotomy. Student paired t-test confirmed a statistically significant difference (P nd the respective one, 2 to 6 months after Nd: Yag capsulotomy (34.5 ± 11 mmHg). All of the cases failed to respond to conservative treatment and were successfully managed with the implantation of Ahmed drainage devices. All patients showed flat filtering bleb and uncontrolled IOP (34.5 ± 11 mmHg), under maximum topical treatment, in a period of 2 to 6 months following Nd: YAG laser caspulotomy. The implantation of Ahmed valve proved to be effective treatment for these patients (IOP nd usually is done without second thought, in this series of eyes, it is postulated that it may be responsible for the deregulation of the filtering bleb and subsequent loss of IOP control. We consider that laser capsulotomy should be performed with caution, especially in eyes with previous trabeculectomy. Also close monitoring of the intraocular pressure and assessment of eventual bleb morphology variations in the follow-up period is mandatory. Further studies are needed in order to confirm our findings.

  17. Selective removal of dental composite with a diode-pumped Er:YAG laser

    Fried, William A.; Chan, Kenneth H.; Darling, Cynthia L.; Fried, Daniel


    Selective removal of dental composite with high precision is best accomplished using lasers operating at high pulse repetition rates focused to a small spot size. Conventional flash-lamp pumped Er:YAG lasers are poorly suited for this purpose, but new diode-pumped Er:YAG lasers have become available operating at high pulse repetition rates. The purpose of this study was to compare the ablation rates and selectivity of enamel and composite for a 30 W diode-pumped Er:YAG laser operating with a pulse duration of 30-50-μs and evaluate it's suitability for the selective removal of composite from tooth surfaces. The depth of ablation and changes in surface morphology were assessed using digital microscopy. The fluence range of 30-50 J/cm2 appeared optimal for the removal of composite, and damage to sound enamel was limited to less than 100-μm after the removal of composite as thick as 700-800-μm. Future studies will focus on the use of methods of feedback to further increase selectivity.

  18. Effects of Er:YAG laser on mineral content of sound dentin in primary teeth.

    Guler, Cigdem; Malkoc, Meral Arslan; Gorgen, Veli Alper; Dilber, Erhan; Bulbul, Mehmet


    The aim of the present study was to evaluate the mineral content of sound dentin in primary teeth prepared using an Er:YAG laser at two different power settings. Thirty-six primary second molars were used in this study. Three dentin slabs were obtained from each tooth, and the slabs were randomly divided into three groups: Group A, control; Group B, Er:YAG laser at 3.5 W, 175 mJ, and 20 Hz, short pulse mode; and Group C, Er:YAG laser at 4 W, 200 mJ, and 20 Hz, medium-short pulse mode. One dentin slab per group was used to evaluate the dentinal morphology and surface roughness values using SEM and profilometer, respectively. Mineral content in the dentin slabs were calculated by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The data were analyzed by one-way analysis of variance and Tukey's HSD tests. No significant differences in Ca, K, Mg, Na, and P levels or Ca/P ratio were found among the groups (P > 0.05). SEM micrographs showed that surface irregularities increased with a higher power setting. The surface roughness after laser treatment in Group B and Group C was found to be similar, unlike Group A.

  19. Sub ablative Er: YAG laser irradiation on surface roughness of eroded dental enamel.

    Curylofo-Zotti, Fabiana Almeida; Lepri, Taísa Penazzo; Colucci, Vivian; Turssi, Cecília Pedroso; Corona, Silmara Aparecida Milori


    This study evaluated the effects of Er:YAG laser irradiation applied at varying pulse repetition rate on the surface roughness of eroded enamel. Bovine enamel slabs (n = 10) were embedded in polyester resin, ground, and polished. To erosive challenges, specimens were immersed two times per day in 20mL of concentrated orange juice (pH = 3.84) under agitation, during a two-day period. Specimens were randomly assigned to irradiation with the Er:YAG laser (focused mode, pulse energy of 60 mJ and energy density of 3.79 J/cm(2) ) operating at 1, 2, 3, or 4 Hz. The control group was left nonirradiated. Surface roughness measurements were recorded post erosion-like formation and further erosive episodes by a profilometer and observed through atomic force microscopy (AFM). Analysis of variance revealed that the control group showed the lowest surface roughness, while laser-irradiated substrates did not differ from each other following post erosion-like lesion formation. According to analysis of covariance, at further erosive episodes, the control group demonstrated lower surface roughness (P > 0.05), than any of the irradiated groups (P dental enamel eroded. The AFM images showed that the specimens irradiated by the Er:YAG laser at 1 Hz presented a less rough surface than those irradiated at 2, 3, and 4 Hz. © 2015 Wiley Periodicals, Inc.

  20. Endoluminal Nd:YAG laser application in ex vivo biliary porcine tissue.

    Rea, Roberta; Di Matteo, Francesco Maria; Martino, Margareth; Pandolfi, Monica; Saccomandi, Paola; Rabitti, Carla; Crescenzi, Anna; Costamagna, Guido


    Adequate biliary drainage with endoscopic or percutaneous placement of self-expandable metal stents represents the goal of palliation in patients with inoperable malignant obstruction of the biliary tree. As an adjunct to stenting, various tissue ablation treatments have been proposed with conflicting results. The aim of this study was to test the effect on biliary tissue of a new ablation technique based on Nd:YAG laser light delivery. The study was conducted on ex vivo specimens of 18 healthy farm pigs, using cystic ducts that are the simplest biliary structures to isolate and cannulate ex vivo. A 22G cannula was positioned into the cystic duct and a quartz optical fibre, with a prototypal cooling system, was inserted into the cannula. Nd:YAG laser output powers of 10, 12, and 15 W were tested, with a total delivered energy of 1000 J in continuous mode in each case. After laser treatment, histological analysis was performed. At macroscopical examination, no lesions of the external wall of the cystic ducts were detected. At histopathological examination, a coagulative necrosis involving the entire mucosa up to the muscolaris propria without significant changes of periductal tissues was observed in all specimens. This study shows the possibility of using Nd:YAG laser on ex vivo porcine biliary ducts with the effect of obtaining a coagulative necrosis involving the whole mucosa.

  1. Long-pulse Nd:YAG 1064-nm laser treatment for onychomycosis

    ZHANG Rui-na; WANG Dong-kun; ZHUO Feng-lin; DUAN Xiao-han; ZHANG Xiao-yan; ZHAO Jun-ying


    Background Recent research shows that lasers can inhibit fungal growth and that Nd:YAG 1064-nm lasers can penetrate as deep as the lower nail plate.The aim of this study was to observe the effect of a long-pulse Nd:YAG 1064-nm laser on 154 nails of 33 patients with clinically and mycologically proven onychomycosis.Methods Thirty-three patients with 154 nails affected by onychomycosis were randomly assigned to two groups,with the 154 nails divided into three sub-groups (Ⅱ degree,Ⅲ degree,and Ⅳ degree) according to the Scoring Clinical Index of Onychomycosis.The 15 patients (78 nails) in group 1 were given eight sessions with a one-week interval,and the 18patients (76 nails) in group 2 were given four sessions with a one-week interval.Results In group 1,the effective rates at 8 weeks,16 weeks,and 24 weeks were 63%,62%,and 51%,respectively,and the effective rates in group 2 were 68%,67%,and 53% respectively.The treatment effect was not significantly different between any sub-group pair (P >0.05).Conclusions Long pulse Nd:YAG 1064-nm laser was effective for onychomycosis.It is a simple and effective method without significant complications or side effects and is expected to become an alternative or replacement therapy for onychomycosis.

  2. Er:YAG and alexandrite laser radiation propagation in the root canal and its effect on bacteria

    Jelinkova, Helena; Dostalova, Tatjana; Duskova, Jana; Miyagi, Mitsunobu; Shoji, Shigeru; Sulc, Jan; Nemec, Michal


    The goal of the study was to verify differences between the alexandrite and Er:YAG laser energy distribution in the root canal and in the surrounding dentin and bone tissues. For the experiment, two lasers were prepared: the Er:YAG laser (λ=2.94 μm) with a delivery system fluorocarbon polymer-coated silver hollow glass waveguide ended by a special sapphire tip and the alexandrite laser (λ=0.75 μm) with a silicon fiber. The Er:YAG laser was operated in a free-running mode, the length of the generated pulses was 250 μsec and the output energy ranged from 100 to 350 mJ. The pulse length of the free- running alexandrite laser was 70 μsec and the output energy was ranged from 80 up to 200 mJ. For the experiment prepared root canals of molars were used. It was ascertained that the radiation of the alexandrite laser passes through the root canal and hits the surrounding tissue. Nocardia asteroids, Filaments, Micrococcus albus, Lactobacillus sp and Streptococcus sanguis colonies were treated by the Er:YAG or alexandrite laser radiation. The surface was checked by scanning electron microscopy. From the result it follows that the Er:YAG laser destroyed microbial colonies but the differences is in the depth of the affected area.

  3. Effects of root surface debridement using Er:YAG laser versus ultrasonic scaling - a SEM study.

    Miremadi, S R; Cosyn, J; Schaubroeck, D; Lang, N P; De Moor, R J G; De Bruyn, H


    Despite promising results of Er:YAG laser in periodontal debridement, to date there is no consensus about the ideal settings for clinical use. This experimental clinical trial aimed to determine the effects of debridement using Er:YAG laser and to compare with ultrasonic treatment. Sixty-four teeth were divided into two in vivo and in vitro subgroups. Each tooth received ultrasonic treatment on one side and Er:YAG laser debridement at either 60, 100, 160 or 250 mJ pulse(-1) and at 10 Hz on the other side on a random basis. All samples were morphologically analyzed afterwards under scanning electron microscope for surface changes and dentinal tubules exposure. Treatment duration (d) was also recorded. Laser debridement produced an irregular, rough and flaky surface free of carbonization or meltdown while ultrasound produced a relatively smoother surface. The number of exposed dentinal tubules (n) followed an energy-dependent trend. The number of exposed tubules among the in vivo laser groups was n 60 mJ = n 100 mJ lasers led to significantly more dentinal exposure than ultrasound under in vivo condition. Within the in vitro laser groups, dentinal tubules exposure was n 60 mJ laser treatments at 100, 160 and 250 mJ led to significantly more dentinal denudation than ultrasound. Treatment duration (d) for the in vivo groups was d 60 mJ > d 100 mJ > d Ultrasound = d 160 mJ > d 250 mJ (P ≤ 0.046), while for the in vitro groups it was d 60 mJ > d 100 mJ = d Ultrasound = d 160 mJ >d 250 mJ (P ≤ 0.046). Due to excessive treatment duration and surface damage, Er:YAG laser debridement at 60 and 250 mJ pulse(-1), respectively, is not appropriate for clinical use. Although laser debridement at 100 and 160 mJ pulse(-1) seems more suitable for clinical application, compared to ultrasound the former is more time-consuming and the latter is more aggressive. Using a feedback device or lower pulse energies are recommended when using laser in closed field. © 2014 John Wiley

  4. Histological and SEM analysis of root cementum following irradiation with Er:YAG and CO2 lasers.

    Almehdi, Aslam; Aoki, Akira; Ichinose, Shizuko; Taniguchi, Yoichi; Sasaki, Katia M; Ejiri, Kenichiro; Sawabe, Masanori; Chui, Chanthoeun; Katagiri, Sayaka; Izumi, Yuichi


    Recently, the Er:YAG and CO(2) lasers have been applied in periodontal therapy. However, the characteristics of laser-irradiated root cementum have not been fully analyzed. The aim of this study was to precisely analyze the alterations of root cementum treated with the Er:YAG and the CO(2) lasers, using non-decalcified thin histological sections. Eleven cementum plates were prepared from extracted human teeth. Pulsed Er:YAG laser contact irradiation was performed in a line at 40 mJ/pulse (14.2 J/cm(2)/pulse) and 25 Hz (1.0 W) under water spray. Continuous CO(2) laser irradiation was performed in non-contact mode at 1.0 W, and ultrasonic instrumentation was performed as a control. The treated samples were subjected to stereomicroscopy, scanning electron microscopy (SEM), light microscopy and SEM energy dispersive X-ray spectroscopy (SEM-EDS). The Er:YAG laser-treated cementum showed minimal alteration with a whitish, slightly ablated surface, whereas CO(2) laser treatment resulted in distinct carbonization. SEM analysis revealed characteristic micro-irregularities of the Er:YAG-lased surface and the melted, resolidified appearance surrounded by major and microcracks of the CO(2)-lased surface. Histological analysis revealed minimal thermal alteration and structural degradation of the Er:YAG laser-irradiated cementum with an affected layer of approximately 20-μm thickness, which partially consisted of two distinct affected layers. The CO(2)-lased cementum revealed multiple affected layers showing different structures/staining with approximately 140 μm thickness. Er:YAG laser irradiation used with water cooling resulted in minimal cementum ablation and thermal changes with a characteristic microstructure of the superficial layer. In contrast, CO(2) laser irradiation produced severely affected distinct multiple layers accompanied by melting and carbonization.

  5. Dual-cavity Nd:YAG laser with Laguerre-Gaussian (LG0n) mode output

    Kim, D. J.; Kim, J. W.


    Direct excitation of an arbitrary Laguerre-Gaussian (LG0n) mode with helical wavefronts in a diode-end-pumped solid state laser employing a dual-cavity configuration is reported. Through simple adjustments of the intra-cavity apertures in the dual-cavity laser configuration, the spatial gain distribution and the cavity loss could be optimized for the targeted LG0 n mode. This approach has been applied to a diode-pumped Nd: YAG laser to achieve selective lasing of the LG01, LG02, and LG03 modes. Also, an optical vortex laser beam was produced directly from the laser resonator by determining the wavefront handedness of each LG mode output using an intra-cavity etalon. The prospects of further power scaling and laser performance improvements will be discussed.

  6. Vortex and LG01-mode Nd:YAG laser involving a circular Dammann grating

    Xu, Yun; Han, Xiahui; Li, Guiyun; Liu, Jinyu; Xia, Kegui; Li, Jianlang


    By introducing a circular Dammann grating (CDG) into the pump unit, we demonstrated an end-pumped Nd:YAG laser that emitted a vortex and first-order LG mode with high laser efficiency and high power. In our scheme, the CDG was used to reshape the pumping light into an annular profile, and the adaptation of it was realized easily by inserting it into the pump unit of a conventional end-pumped solid-state laser; the laser cavity was simple, compact, and consisted of only a laser crystal and an output coupler. The beam power of this laser reached 1.86 W at an absorbed pump power of 6.38 W with a slope efficiency of 34.5%.

  7. Periodic surface structures on crystalline silicon created by 532 nm picosecond Nd:YAG laser pulses

    Trtica, M.S. [Physical Chemistry Department, Vinca Institute of Nuclear Sciences, P.O. BOX 522, 11001 Belgrade (Serbia)], E-mail:; Gakovic, B.M. [Atomic Physics Department, Vinca Institute of Nuclear Sciences, P.O. BOX 522, 11001 Belgrade (Serbia); Radak, B.B. [Physical Chemistry Department, Vinca Institute of Nuclear Sciences, P.O. BOX 522, 11001 Belgrade (Serbia); Batani, D.; Desai, T.; Bussoli, M. [Dipartimento di Fisica ' G. Occhialini' , Universita degli Studi di Milano Bicocca, Piazza della Scienza 3, 20126 Milano (Italy)


    Creation of laser-induced morphology features, particularly laser-induced periodic surface structures (LIPSS), by a 532 nm picosecond Nd:YAG laser on crystalline silicon is reported. The LIPSS, often termed ripples, were produced at average laser irradiation fluences of 0.7, 1.6, and 7.9 J cm{sup -2}. Two types of ripples were registered: micro-ripples (at micrometer scale) in the form of straight parallel lines extending over the entire irradiated spot, and nano-ripples (at nanometer scale), apparently concentric, registered only at the rim of the spot, with the periodicity dependent on laser fluence. There are indications that the parallel ripples are a consequence of the partial periodicity contained in the diffraction modulated laser beam, and the nano-ripples are very likely frozen capillary waves. The damage threshold fluence was estimated at 0.6 J cm{sup -2}.

  8. Clinical evaluation of Er:YAG laser caries treatment

    Dostalova, Tatjana; Jelinkova, Helena; Kucerova, Hana; Krejsa, Otakar; Hamal, Karel; Kubelka, Jiri; Prochazka, Stanislav


    To prepare the enamel, the energy used was mainly 345 mJ and repetition rate 2 Hz, for dentine the optimal energy of Er:YAG drilling machine was 200 mJ and repetition rate from 1 to 2 Hz, depending on cavity depth. Subject of treatment were caries of enamel and dentine and it was possible to remove the old insufficient fillings. The average number of pulses was 111.22, ranging from 16 to 489. During preparation, vibrations of microexplosions were felt by 8 patients, however, neither pain or unpleasant sensations were experienced. The filling materials used were composite resins and glassionomer cements. Their clinical evaluation 6 months post insertion was similar to that of the classical drilling system.

  9. Freeze frame analysis on high speed cinematography of Nd/YAG laser explosions in ocular tissues.

    Vernon, S A; Cheng, H


    High speed colour cinematography at 400 frames per second was used to photograph both single and train burst Nd/YAG laser applications in ox eyes at threshold energy levels. Measurements of the extent and speed of particle scatter and tissue distortion from the acoustic transient were made from a sequential freeze frame analysis of the films. Particles were observed to travel over 8 mm from the site of Nd/YAG application 20 milliseconds after a single pulse at initial speeds in excess of 20 km/h. The use of train bursts of pulses was seen to increase the number of particles scattered and project the wavefront of particles further from the point of laser application.

  10. Inner structure detection by optical tomography technology based on feedback of microchip Nd:YAG lasers.

    Xu, Chunxin; Zhang, Shulian; Tan, Yidong; Zhao, Shijie


    We describe a new optical tomography technology based on feedback of microchip Nd:YAG lasers. In the case of feedback light frequency-shifted, light can be magnified by a fact of 10(6) in the Nd:YAG microchip lasers, which makes it possible to realize optical tomography with a greater depth than current optical tomography. The results of the measuring and imaging of kinds of samples are presented, which demonstrate the feasibility and potential of this approach in the inner structure detection. The system has a lateral resolution of ~1 μm, a vertical resolution of 15 μm and a longitudinal scanning range of over 10mm.

  11. Healing of bone in the rat following surgery with the erbium-YAG laser

    Dickinson, Mark R.; Devlin, Hugh; El Montaser, Monsour A.; Sloan, Philip


    Background and objectives: the aim of this study was to examine the pattern of healing in rat calvarial defects prepared with the erbium-YAG laser, using the 'guided tissue regeneration' technique. Materials and method: PTFE membranes were placed over lased skull defects, and the skin wounds sutured. Rats were killed humanely at intervals after surgery, and the skulls processed for paraffin wax histology. A further group of mature rats were also killed humanely and the calvariae removed. Slots were prepared using the erbium-YAG laser and immediately examined under the environmental scanning electron microscope (ESEM) in hydrated conditions, which avoided drying artifacts. Results: An amorphous, mineral-rich carbon layer surrounds the lased bone defect, which in the in vivo experiments was seen as a basophilic zone which was resistant to resorption.

  12. Dual-rod Yb: YAG laser for high-power and high-brightness applications

    Honea, E C; Beach, R; Mitchell, S C; Skidmore, J A; Emanuel, M A; Sutton, S B; Payne, S A; Avizonis, P V; Monroe, R S; Harris, D G


    The authors describe a diode-pumped Yb:YAG laser producing 1,080 W cw with 27.5% optical-optical efficiency and 532 W Q-switched with M{sup 2} = 2.2 and 17% optical-optical efficiency. The laser uses two composite Yb:YAG rods separated by a 90 degree quartz rotator for bifocusing compensation. A microlensed diode array end-pumps each rod using a hollow lens duct for pump delivery. By changing resonator parameters, they can adjust the fundamental mode size and the output beam quality. Using a flattened gaussian intensity profile to calculate the mode fill efficiency and clipping losses, the authors compare experimental data to modeled output power vs beam quality.

  13. Yb:YAG ceramic-based laser driver for Inertial Fusion Energy (IFE)

    Vetrovec, John; Copeland, Drew A.; Litt, Amardeep S.


    We report on a new class of laser amplifiers for inertial confinement fusion (ICF) drivers based on a Yb:YAG ceramic disk in an edge-pumped configuration and cooled by a high-velocity gas flow. The Yb lasant offers very high efficiency and low waste heat. The ceramic host material has a thermal conductivity nearly 15-times higher than the traditionally used glass and it is producible in sizes suitable for a typical 10- to 20-kJ driver beam line. The combination of high lasant efficiency, low waste heat, edge-pumping, and excellent thermal conductivity of the host, enable operation at 10 to 20 Hz at over 20% wall plug efficiency while being comparably smaller and less costly than recently considered face-pumped alternative drivers using Nd:glass, Yb:S-FAP, and cryogenic Yb:YAG. Scalability of the laser driver over a broad range of sizes is presented.

  14. Clinical assessments of the erbium:YAG laser for soft tissue surgery and scaling.

    Watanabe, H; Ishikawa, I; Suzuki, M; Hasegawa, K


    We evaluated the clinical usefulness of an erbium:YAG laser for soft tissue surgery, and scaling. Thirty-one patients with soft tissue lesions (13 males and 18 females from 24 to 71 years old), and 60 patients with calculus deposits (21 males and 39 females from 19 to 72 years old) were treated with the laser. The clinical parameters evaluated were pain, redness, swelling of the gingiva, and the subjective patient comfort parameters including uneasiness with the sound and vibration associated with laser treatment. Additionally, hemorrhage and wound healing during and after the surgery, the roughness of the root surface after scaling, and the effectiveness of scaling using the laser were examined. Laser surgery caused less hemorrhage and resulted in better wound healing when compared with conventional methods. It was easy to remove calculi from the root surface with the laser in 95% of the cases. Although the scaled site showed some irregularity, it was not clinically significant in 98% of the cases. Only a few patients complained about the unpleasant sound and vibration. There were no complications or side effects during this clinical trial. Thus, this study suggests that an Er:YAG laser is useful for soft tissue surgery and scaling.

  15. Polycarbonate surface cell's adhesion examination after Nd:YAG laser irradiation

    Ramazani, S.A. Ahmad, E-mail: [Polymer Group, Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Mousavi, Seyyed Abbas, E-mail: [Department of Chemistry, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Seyedjafari, Ehsan [Department of Biotechnology, University College of Science, University of Tehran (Iran, Islamic Republic of); Poursalehi, Reza [Department of Physics, University of Shahed, Tehran (Iran, Islamic Republic of); Sareh, Shohreh [Research Center of Iranian Blood Transfusion Organization, Tehran (Iran, Islamic Republic of); Silakhori, Kaveh [Laser Research Center, Atomic Energy Organization, Tehran (Iran, Islamic Republic of); Poorfatollah, Ali Akbar [Research Center of Iranian Blood Transfusion Organization, Tehran (Iran, Islamic Republic of); Shamkhali, Amir Nasser [Department of Chemistry, Sharif University of Technology, Tehran (Iran, Islamic Republic of)


    Nd:YAG laser treatment was used in order to increase surface cell adhesion aspects of polycarbonate (PC) films prepared via melt process. The treatment was carried out under different wavelengths and beam diameters. ATR-FTIR and UV spectra obtained from different samples before and after laser treatment in air showed that laser irradiation has induced some chemical and physical changes in surface properties. The irradiated films were also characterized using scanning electron microscopy (SEM) and contact angle measurements. Effect of pulse numbers on the surface properties was also investigated. Cell culture test was used to evaluate cell adhesion property on the PC films before and after treatment. The results obtained from this test showed that after laser treatment, the cells were attached and proliferated extensively on the Nd:YAG laser treated films in comparison with the unmodified PC. Moreover, it was revealed that a decrease in the laser beam diameter and an increase in the irradiated pulse numbers increased surface wettability and caused a better cell attachment on the polymer surface. The obtained results also showed that a decrease in the laser beam diameter and an increase in the irradiated pulse numbers increased surface wettability and caused a better cell attachment on the polymer surface.

  16. Pulsed laser deposition process of PLZT thin films using an infrared Nd:YAG laser

    Garcia, T. [CCADET-UNAM, A.P. 70-186, Mexico D.F., C.P. 04510 (Mexico)]. E-mail:; Posada, E. de [IMRE-Physics Faculty, Havana University (Cuba); Bartolo-Perez, P. [CINVESTAV-IPN Unidad, Applied Physics Department, A.P. 73 Cordemex, Merida, Yuc. (Mexico); Programa de Corrosion del Golfo de Mexico, UAC, Compeche (Mexico); Pena, J.L. [CINVESTAV-IPN Unidad, Applied Physics Department, A.P. 73 Cordemex, Merida, Yuc. (Mexico); Diamant, R. [UAM-Unidad Iztapalapa, D.F. (Mexico); Calderon, F. [IMRE-Physics Faculty, Havana University (Cuba); Pelaiz, A. [IMRE-Physics Faculty, Havana University (Cuba)


    Pulsed laser depositions of PLZT thin films were performed using an Nd:YAG (1064 nm) laser. The growths took place in vacuum or in an oxygen background. Room temperature and 500 deg. C were the used substrate temperatures. The X-ray diffraction analysis revealed a preferential crystallographic orientation in the films grown at room temperature in vacuum. Such result is discussed. The velocity distribution functions of the species in the plasma plume were obtained from a time of flight study using optical emission spectroscopy. The maximums of these distributions functions fall around 10{sup 6} cm/s, equivalent to an energy range of 18-344 eV. Ionic species of heavy elements (like lead) achieved higher velocities than other lighter species. This result is linked to the creation of an accelerating spatial charge and to the thermal nature of the target material extraction that allows some elements to be released first than others. Chemical state variations of the elements present in the films were analyzed. Under these different growing conditions, lead chemical states varied the most.

  17. Analysis of therapeutical effects of Er:YAG and CO2 laser post treatments of small hemangiomas

    Remlová, E.; Vránová, J.; Rosina, J.; Navrátil, L.


    The main goal of our study was the evaluation of treatment efficiency of two types of ablative laser-CO2 and Er:YAG (or ERB) treatment. 183 patients (Er:YAG—105 patients, CO2—78 patients) were analyzed to compare the curative effects and adverse events, such as loss of pigment and appearance of scars caused by these two lasers. The results of the study showed the slightly better effectiveness of Er:YAG laser radiation in comparison with CO2 laser in the case of treatment of small hemangiomas up to 3 mm in diameter. In the Er:YAG laser application the curative effect was in 99%, hypo-pigmentation occurred in 18%, and scars in 70% of all treatments. In the CO2 laser application the curative effect was in 97%, hypo-pigmentation in 52%, and scars in 77% from all treatments.

  18. 8-mJ TEM(00) diode-end-pumped frequency-quadrupled Nd:YAG laser.

    Feugnet, G; Pocholle, J P


    A frequency-quadrupled Nd:YAG laser pumped by a commercially available high-brightness stack is described. A master oscillator power amplifier configuration was implanted, and the laser delivered energy of 8 mJ at 0.266microm . The laser was air cooled for easy use.

  19. Digital laser mode amplification using ND: YAG amplifier

    Bell, Teboho


    Full Text Available the power of the mode when it is transmitted through the amplifier. INTRODUCTION The DPSSDL has attracted widespread attention due to ability of generation on- demand laser modes [1]. Diode lasers are the preferred pump for high power lasers, due to better... since they are manufactured for a fixed mode. The DPSSDL has a power limitations, since the end-mirror of the resonator is an SLM, which have low damage threshold. Due to the SLM's efficiency and low damage threshold, the output beam of digital laser...

  20. Corneal photoablation in vivo with the erbium:YAG laser: first report

    Jean, Benedikt J.; Bende, Thomas; Matallana, Michael; Kriegerowski, Martin


    As an alternative to far-UV lasers for corneal refractive surgery, the Erbium:YAG laser may be used in TEM00 mode. The resulting gaussian beam profile leads to a certain amount of myopic correction per laser pulse. Although animal data suggest that the clinical outcome should be comparable to the UV-lasers, no human data were available until now. We performed Erbium:YAG laser areal ablation in 5 blind human eyes. In TEM00 mode, the laser parameters were: effective diameter of laser spot equals 3.4 mm, fluence equals 380 mJ/cm2, pulse duration equals 250 microsecond(s) , Repetition rate equals 4 Hz, Number of applied laser pulses equals 15. Four patients with no light perception, one with intact light projection on one eye (some of them scheduled for enucleation) were treated under topical anaesthesia. Patient selection and informed consent were agreed to by the University's independent Ethics Committee. Prior to laser irradiation, corneal epithelium was removed. A postoperative silicone cast of the cornea was analyzed with a confocal laser micro-topometer for the ablation profile. The eyes were treated with antibiotic ointment until the epithelium was closed. Clinical appearance and, where possible, profilometry of the ablated area was observed. The ablation profile in cornea was gaussian shaped with a maximal depth of 30 micrometers . During laser treatment, the corneal surface becomes opaque, clearing in a matter of seconds. Epithelial healing and clinical appearance was similar to excimer laser treatment. However, during the first week, the irradiated area shows subepithelial irregularities, resembling small bubbles, disappearing thereafter.

  1. 1.32 μm Nd3+∶YAG Pulse Laser

    WANG Zhaoying; WU Xing


    Using specially coated mirrors, an output energy of 0.97 J at 1.32 μm from a Nd3+∶YAG pulse laser is obtained with pumping energy of 66 J. The repetition rate is 1 pulse/sec and the slope efficiency is 1.7%. The repetition rate can be changed from 1 pulse/sec to 10 pulses/sec.

  2. Electro-optical cavity-dumped Ce:Nd:YAG laser for aesthetic medicine

    Lv, Yuandong; Liu, Jiaqi; Hao, Lijun


    An electro-optical cavity-dumped 20 Hz Ce:Nd:YAG laser with an optimized thermal-insensitive concavo-convex cavity for aesthetic medicine was demonstrated. The pulse width remained constant at 6.0 ns. The maximum output energy and peak power were 120 mJ and 20 MW, respectively. The average output energy was very stable. The fluctuations of average output energy within 6 cycles and 10 min were 0.89% and 7.9%, respectively.

  3. Polarization Self-Modulation Phenomenon in a Free Oscillated Nd: YAG Laser

    YANG Qian-Suo; LUO Geng-Xing; ZOU Nian-Yu; YANG Guo-Wei; ZHU Nai-Yi


    @@ Polarization self-modulation effect in a free oscillated Nd:YAG laser is investigated after a quarter wave plate is introduced independently in the two positions of the cavity. As described in the previous experiments, the intensity components in the orthogonal directions are modulated with a period of the round-trip time or twice.Different pulse shapes reveal that the seed field from the spontaneous emission is not uniform and seems to be stochastic for each pulse.

  4. Diode-pumped Solid-state Cr4+∶Nd∶YAG/KTP Green Laser

    YU Ting; CUI Junwen; LU Yutian; HU Qiquan


    A diode-pumped solid-state Cr4+∶Nd∶YAG/KTP green laser with intracavity second harmonic generation is reported. Stable quasi-cw output of 1.03 W in average power, 100 kHz of repetition rate and about 25 ns of pulse width were obtained. Repetition rate and pulse width were studied experimentally and analyzed under different conditions.

  5. Effects of Er:YAG laser irradiation on the microtensile bond strength to bleached enamel.

    Leonetti, Eduardo dos Santos; Rodrigues, José Augusto; Reis, André Figueiredo; Navarro, Ricardo Scarparo; Aranha, Ana Cecília Correa; Cassoni, Alessandra


    The objective of this study was to evaluate the influence of different Er:YAG laser (λ = 2.94  μm) energy parameters on the microtensile bond strength (μTBS) and superficial morphology of bovine enamel bleached with 16% carbamide peroxide. Laser irradiation could improve adhesion to bleached enamel surfaces. Sixty bovine enamel blocks (7 × 3 × 3  mm(3)) were randomly assigned to six groups according to enamel preparation procedures (n = 10): G1-bleaching and Er:YAG laser irradiation with 25.52  J/cm(2) (laser A, LA); G2-bleaching and Er:YAG laser irradiation with 4.42 J/cm(2) (laser B, LB); G3-bleaching; G4-Er:YAG laser irradiation with 25.52  J/cm(2); G5-Er:YAG laser irradiation with 4.42 J/cm(2); G6-control, no treatment. G1 to G3 were bleached for 6  h during 21 days. Afterwards, enamel surfaces in all groups were slightly abraded with 600-grit SiC papers and G1, G2, G4 and G5 were irradiated according to each protocol. Enamel blocks were then restored with an etch-and-rinse adhesive system and a 4-mm thick composite buildup was made in two increments (n = 9). After 24  h, restored blocks were serially sectioned with a cross-section area of ∼1  mm(2) at the bonded interface and tested in tension in a universal testing machine (1  mm/min). Failure mode was determined at a magnification of x100 using a stereomicroscope. One treated block of each group was selected for scanning electron microscopy (SEM) analysis. μTBS data were analyzed by two-way ANOVA and no statistical differences were observed among groups. Mean bond strengths (SD) in MPa were: G1-30.4(6.2); G2-27.9(8.5); G3-32.3(3.9); G4-23.7(5.8); G5-29.3(6.0); G6-29.1(6.1). A large number of adhesive failures was recorded for bleached and irradiated enamel surfaces. Bleached enamel surfaces μTBS values were not significantly different from those of unbleached enamel. Even though Er:YAG laser irradiation with both parameters had no influence on μTBS for bleached

  6. Effect of Nd: YAG laser irradiation on surface properties and bond strength of zirconia ceramics.

    Liu, Li; Liu, Suogang; Song, Xiaomeng; Zhu, Qingping; Zhang, Wei


    This study investigated the effect of neodymium-doped yttrium aluminum garnet (Nd: YAG) laser irradiation on surface properties and bond strength of zirconia ceramics. Specimens of zirconia ceramic pieces were divided into 11 groups according to surface treatments as follows: one control group (no treatment), one air abrasion group, and nine laser groups (Nd: YAG irradiation). The laser groups were divided by applying with different output power (1, 2, or 3 W) and irradiation time (30, 60, or 90 s). Following surface treatments, the morphological characteristics of ceramic pieces was observed, and the surface roughness was measured. All specimens were bonded to resin cement. After, stored in water for 24 h and additionally aged by thermocycling, the shear bond strength was measured. Dunnett's t test and one-way ANOVA were performed as the statistical analyses for the surface roughness and the shear bond strength, respectively, with α = .05. Rougher surface of the ceramics could be obtained by laser irradiation with higher output power (2 and 3 W). However, cracks and defects were also found on material surface. The shear bond strength of laser groups was not obviously increased, and it was significantly lower than that of air abrasion group. No significant differences of the shear bond strength were found among laser groups treated with different output power or irradiation time. Nd: YAG laser irradiation cannot improve the surface properties of zirconia ceramics and cannot increase the bond strength of the ceramics. Enhancing irradiation power and extending irradiation time cannot induce higher bond strength of the ceramics and may cause material defect.

  7. Clinical and bacteriological study of the effect of Nd:YAG laser in gingivitis therapy

    Colojoara, Carmen; Mavrantoni, Androniki; Miron, Mariana I.


    The relationship between dental plaque and gingivitis was verified. Nonspecific gingivitis is an inflammatory process, frequently caused by enzymes and toxins liberate by bacteria form dental plaque. Loose plaque has come under a great deal of investigation because of its role in attachment loss. The current methods used in the treatment of non specific gingivitis encompass the use of antibiotics and conventional surgical techniques. Treating gingivitis with laser energy may further reduce the gingival inflammation and decrease the wound healing time. The lack of correlation between the quantity of dental plaque and the intensity of gingivitis determined us to study the effect of Nd:YAG pulsed laser in reduction of gingival inflammation and wound healing. The aim of this work is to evaluate clinically the anti- inflammatory and wound healing effect of pulsed Nd:YAG laser and to compare the appearance and the levels of the bacteria in the supergingival and subgingival plaque in adolescents with tooth crowding after Nd:YAG laser. The experimental procedure consisted of a clinical and bacteriological study which was undertaken in 20 patients presenting moderate gingivitis. A group of 10 patients was the subject of a bacteriological study and the other group of 10 was used for clinical and histological examination. For each group the clinical criteria of evaluation were: the gingival index, papillary bleeding index, spontaneous aches. Each patient was tested before and after laser exposure or conventional therapy for bacteriological analyses. The results prove that early gingivitis exposure to laser registers a decrease of bacterial colony number and absence of loss of attachment as compared to the application of the conventional treatment. Clinical study has shown that the combination of scaling and root planning with laser therapy is enough to provide improvement in clinical indices and reduction in the number of bacterial colonies.

  8. Argon green-Nd: YAG dual laser posterior hyaloidotomy: An innovative approach toward treatment of premacular hemorrhage

    Ashish Sharma


    Full Text Available Background: Neodymium: YAG (Nd: YAG laser and argon laser has been used to treat premacular hemorrhage either alone or rarely in combination. Materials and Methods: We describe a new technique of treating premacular hemorrhage by performing hyaloidotomy using a combination of argon green-Nd: YAG laser. We utilized subthreshold energy levels of Nd: YAG laser of 2.0 mJ as compared to the normal recommendation of 3.6-50 mJ. Results and Conclusions: This technique is easy, effective, and safe to manage premacular hemorrhage. The principle behind this combined laser treatment was to make the internal limiting membrane (ILM taut by initial exposure to argon green laser, which allowed us to employ the subthreshold energy levels of Nd: YAG laser. We would like to assess the role of this combined treatment modality in comparison to other modalities, including solitary laser therapy in the management of premacular hemorrhage by performing a prospective, randomized long-term study.

  9. Generation of bright attosecond x-ray pulse trains via Thomson scattering from laser-plasma accelerators.

    Luo, W; Yu, T P; Chen, M; Song, Y M; Zhu, Z C; Ma, Y Y; Zhuo, H B


    Generation of attosecond x-ray pulse attracts more and more attention within the advanced light source user community due to its potentially wide applications. Here we propose an all-optical scheme to generate bright, attosecond hard x-ray pulse trains by Thomson backscattering of similarly structured electron beams produced in a vacuum channel by a tightly focused laser pulse. Design parameters for a proof-of-concept experiment are presented and demonstrated by using a particle-in-cell code and a four-dimensional laser-Compton scattering simulation code to model both the laser-based electron acceleration and Thomson scattering processes. Trains of 200 attosecond duration hard x-ray pulses holding stable longitudinal spacing with photon energies approaching 50 keV and maximum achievable peak brightness up to 1020 photons/s/mm2/mrad2/0.1%BW for each micro-bunch are observed. The suggested physical scheme for attosecond x-ray pulse trains generation may directly access the fastest time scales relevant to electron dynamics in atoms, molecules and materials.

  10. Fluorescence imaging of lattice re-distribution on step-index direct laser written Nd:YAG waveguide lasers

    Martínez de Mendívil, Jon; Pérez Delgado, Alberto; Lifante, Ginés; Jaque, Daniel [Departamento de Física de Materiales, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049 (Spain); Ródenas, Airán [Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, Tarragona 43007 (Spain); Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Benayas, Antonio, E-mail: [Departamento de Física de Materiales, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049 (Spain); Institut National de la Recherche Scientifique, Centre – Énergie Matériaux et Télécommunications, 1650, Boul. Lionel Boulet Varennes, Quebec J3X 1S2 (Canada); Aguiló, Magdalena; Diaz, Francesc [Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, Tarragona 43007 (Spain); Kar, Ajoy K. [Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom)


    The laser performance and crystalline micro-structural properties of near-infrared step-index channel waveguides fabricated inside Neodymium doped YAG laser ceramics by means of three-dimensional sub-picosecond pulse laser direct writing are reported. Fluorescence micro-mapping of the waveguide cross-sections reveals that an essential crystal lattice re-distribution has been induced after short pulse irradiation. Such lattice re-distribution is evidenced at the waveguide core corresponding to the laser written refractive index increased volume. The waveguides core surroundings also present diverse changes including slight lattice disorder and bi-axial strain fields. The step-index waveguide laser performance is compared with previous laser fabricated waveguides with a stress-optic guiding mechanism in absence of laser induced lattice re-distribution.

  11. Fluorescence imaging of lattice re-distribution on step-index direct laser written Nd:YAG waveguide lasers

    Martínez de Mendívil, Jon; Ródenas, Airán; Benayas, Antonio; Aguiló, Magdalena; Diaz, Francesc; Pérez Delgado, Alberto; Lifante, Ginés; Jaque, Daniel; Kar, Ajoy K.


    The laser performance and crystalline micro-structural properties of near-infrared step-index channel waveguides fabricated inside Neodymium doped YAG laser ceramics by means of three-dimensional sub-picosecond pulse laser direct writing are reported. Fluorescence micro-mapping of the waveguide cross-sections reveals that an essential crystal lattice re-distribution has been induced after short pulse irradiation. Such lattice re-distribution is evidenced at the waveguide core corresponding to the laser written refractive index increased volume. The waveguides core surroundings also present diverse changes including slight lattice disorder and bi-axial strain fields. The step-index waveguide laser performance is compared with previous laser fabricated waveguides with a stress-optic guiding mechanism in absence of laser induced lattice re-distribution.

  12. Selected area laser-crystallized polycrystalline silicon thin films by a pulsed Nd:YAG laser with 355 nm wavelength

    Duan Chunyan; Liu Chao; Ai Bin; Lai Jianjun; Deng Youjun; Shen Hui


    Selected area laser-crystallized polycrystalline silicon(p-Si)thin films were prepared by the third harmonics(355 nm wavelength)generated by a solid-state pulsed Nd:YAG laser.Surface morphologies of 400 nm thick films after laser irradiation were analyzed.Raman spectra show that film crystallinity is improved with increase of laser energy.The optimum laser energy density is sensitive to the film thickness.The laser energy density for efficiently crystallizing amorphous silicon films is between 440-634 mJ/cm2 for 300 nm thick films and between 777-993 mJ/cm2 for 400 nm thick films.The optimized laser energy density is 634,975 and 1571 mJ/cm2 for 300,400 and 500 nm thick films,respectively.

  13. Morphological changes produced by acid dissolution in Er:YAG laser irradiated dental enamel.

    Manuela Díaz-Monroy, Jennifer; Contreras-Bulnes, Rosalía; Fernando Olea-Mejía, Oscar; Emma Rodríguez-Vilchis, Laura; Sanchez-Flores, Ignacio


    Several scientific reports have shown the effects of Er:YAG laser irradiation on enamel morphology. However, there is lack of information regarding the morphological alterations produced by the acid attack on the irradiated surfaces. The aim of this study was to evaluate the morphological changes produced by acid dissolution in Er:YAG laser irradiated dental enamel. Forty-eight enamel samples were divided into four groups (n = 12). GI (control); Groups II, III, and IV were irradiated with Er:YAG at 100 mJ (12.7 J/cm(2) ), 200 mJ (25.5 J/cm(2) ), and 300 mJ (38.2 J/cm(2) ), respectively, at 10 Hz without water irrigation. Enamel morphology was evaluated before-irradiation, after-irradiation, and after-acid dissolution, by scanning electron microscopy (SEM). Sample coating was avoided and SEM analysis was performed in a low-vacuum mode. To facilitate the location of the assessment area, a reference point was marked. Morphological changes produced by acid dissolution of irradiated enamel were observed, specifically on laser-induced undesired effects. These morphological changes were from mild to severe, depending on the presence of after-irradiation undesired effects.

  14. [Use of airway stent subsequent to endoscopic Nd-YAG laser treatment in central airway obstruction].

    Akaogi, E; Yuasa, H; Ishibashi, O; Inage, Y; Dai, Y; Sato, Y; Ishikawa, S; Morita, R; Onizuka, M; Mitsui, K


    Ten cases of central airway obstruction mainly caused by extrinsic compression due to the growth of extratracheal malignant tumors or longitudinal extension of tracheal adenoid cystic carcinomas, underwent palliative intubation subsequent to endoscopic Nd-YAG laser treatment. Mean length of the severe stenosis in these cases was 4.4 cm (3-7 cm). Sole application of endoscopic Nd-YAG laser to the stenosis failed relief of the symptom and an immediate palliative intubation was recommended. Mean time of the temporary intubation was 7 days (4-11 days). Airway was maintained by this intubation and also retained enough after extubation. Therefore, it seemed that, in a palliative treatment of the central airway severe stenosis, usefulness of the combination management of Nd-YAG laser with following temporary intubation was revealed. However, in order to maintain the airway for recurrence of the obstruction, use of indwelling airway stents seemed a better application. The longest period of follow-up in the cases treated by indwelling airway stents was 6 months and one of the cases is a now in comfortable state.

  15. Surface nanomorphology of human dental enamel irradiated with an Er:YAG laser

    Ţălu, Ş.; Contreras–Bulnes, R.; Morozov, I. A.; Rodríguez-Vilchis, L. E.; Montoya-Ayala, G.


    To determine the effects of Er:YAG laser irradiation on the surface nanomorphology of human dental enamel. Materials and methods: five samples of human dental enamel were divided into five groups: (a) I and II were irradiated with Er:YAG & water irrigation (12.7 J cm-2 and 25.5 J cm-2, respectively); (b) III and IV were Er:YAG laser irradiated & no water irrigation (12.7 J cm-2 and 25.5 J cm-2, respectively); (c) V or control (no laser irradiation). Nanomorphological changes were observed on 1 μm  ×  1 μm areas by AFM (contact mode and air). The partition functions and multifractal spectra were calculated. The graphical results showed that the larger the spectrum width Δα (Δα  =  α max  -  α min) of the multifractal spectra f(α) the more non-uniform the surface nanomorphology. One way analysis of variance (ANOVA) was performed (P  roughness parameters, and multifractal analysis provided useful information about the surface nanomorphology and optimal surface characteristics. This approach could be extended to other enamel surfaces in order to characterize its structural 3D microrelief.

  16. Single session of Nd:YAG laser intracanal irradiation neutralizes endotoxin in dental root dentin

    Archilla, José R. F.; Moreira, Maria S. N. A.; Miyagi, Sueli P. H.; Bombana, Antônio C.; Gutknecht, Norbert; Marques, Márcia M.


    Endotoxins released in the dental root by Gram-negative microorganisms can be neutralized by calcium hydroxide, when this medication is applied inside the root canal for at least seven days. However, several clinical situations demand faster root canal decontamination. Thus, for faster endotoxin neutralization, endodontists are seeking additional treatments. The in vitro study tested whether or not intracanal Nd:YAG laser irradiation would be able to neutralize endotoxin within the human dental root canal in a single session. Twenty-four human teeth with one root were mounted between two chambers. After conventional endodontic treatment, root canals were contaminated with Escherichia coli endotoxin. Then they were irradiated or not (controls) in contact mode with an Nd:YAG laser (1.5 W, 15 Hz, 100 mJ and pulse fluency of 124 J/cm2). The endotoxin activity was measured using the limulus lysate technique and data were statistically compared (p≤0.05). The concentration of active endotoxin measured in the negative control group was significantly lower than that of the positive control group (p=0.04). The concentrations of endotoxin in both irradiated groups were significantly lower than that of the positive control group (p=0.027) and similar to that of negative control group (p=0.20). A single session of intracanal Nd:YAG laser irradiation is able to neutralize endotoxin in the dental root tissues.

  17. In vitro studies of morphological changes in enamel surface after Er:YAG and Nd:YAG laser irradiation, by SEM; Estudo in vitro do efeito do laser Nd:YAG e Er:YAG sobre o esmalte dental humano atraves de microscopia eletronica de varredura

    Verlangieri, Eleonora Jaeger


    The caries prevention by using laser irradiation has been investigated by many authors using various lasers with different irradiations conditions. The purpose of this study was to investigated the morphological changes in enamel surface after Er:YAG and Nd:YAG laser irradiation, in vitro, by SEM. Fifteen freshly extracted, intact, caries-free, human third molars, were used in this study. The coronary portions were sectioned, from buccal to lingual direction, in two half-parts. Each one was irradiated by a different laser. The first one was irradiated with water-air spray, by a Nd:YAG laser, at 1.084 nm wave length, at 10 W, 10 Hz, 100 mJ for 60 sec., with an optical fiber in contact mode (0,32 mm of diameter); and the other half, with water-air spray by an Er:YAG laser at 2,94 micrometers wave length at the parameters of 4 Hz, 80 mJ, 24.95 J/cm{sup 2} for 60 sec. The results of this study suggested that both lasers promoted morphological changes in the enamel surface enhancing resistance and can be an alternative clinical method for caries preventions. (author)

  18. Short-pulse Er:YAG laser increases bond strength of composite resin to sound and eroded dentin

    Cersosimo, Maria Cecília Pereira; Matos, Adriana Bona; Couto, Roberta Souza D.'Almeida; Marques, Márcia Martins; de Freitas, Patricia Moreira


    This study evaluated the influence of the irradiation with a short-pulse Er:YAG laser on the adhesion of composite resin to sound and eroded dentin (SD and ED). Forty-six samples of occlusal dentine, obtained from human molars, had half of their surface protected, while the other half was submitted to erosive cycles. Afterward, 23 samples were irradiated with Er:YAG laser, resulting in four experimental groups: SD, sound irradiated dentine (SID-Er:YAG, 50 μs, 2 Hz, 80 mJ, and 12.6 J/cm2), ED, and eroded irradiated dentin (EID-erosion + Er:YAG laser). A self-etching adhesive system was used, and then cylinders of composite resin were prepared. A microshear bond strength test was performed after 24 h storage (n=20). The morphology of SD and ED, with or without Er:YAG laser irradiation, was evaluated under scanning electron microscopy (n=3). Bond strength values (MPa) were subjected to analysis of variance followed by Tukey's test. Statistically significant differences were found among the experimental groups: SD (9.76±3.39 B), SID (12.77±5.09 A), ED (5.12±1.72 D), and EID (7.62±3.39 C). Even though erosion reduces the adhesion to dentin, the surface irradiation with a short-pulse Er:YAG laser increases adhesion to both ED and SD.

  19. Parametric Optimization of Nd:YAG Laser Beam Machining Process Using Artificial Bee Colony Algorithm

    Rajarshi Mukherjee


    Full Text Available Nd:YAG laser beam machining (LBM process has a great potential to manufacture intricate shaped microproducts with its unique characteristics. In practical applications, such as drilling, grooving, cutting, or scribing, the optimal combination of Nd:YAG LBM process parameters needs to be sought out to provide the desired machining performance. Several mathematical techniques, like Taguchi method, desirability function, grey relational analysis, and genetic algorithm, have already been applied for parametric optimization of Nd:YAG LBM processes, but in most of the cases, suboptimal or near optimal solutions have been reached. This paper focuses on the application of artificial bee colony (ABC algorithm to determine the optimal Nd:YAG LBM process parameters while considering both single and multiobjective optimization of the responses. A comparative study with other population-based algorithms, like genetic algorithm, particle swarm optimization, and ant colony optimization algorithm, proves the global applicability and acceptability of ABC algorithm for parametric optimization. In this algorithm, exchange of information amongst the onlooker bees minimizes the search iteration for the global optimal and avoids generation of suboptimal solutions. The results of two sample paired t-tests also demonstrate its superiority over the other optimization algorithms.

  20. The effect of Er:YAG laser irradiation on the surface microstructure and roughness of hydroxyapatite-coated implant


    Purpose The present study was performed to evaluate the effect of erbium:yttrium-aluminium-garnet (Er:YAG) laser irradiation on the change of hydroxyapatite (HA)-coated implant surface microstructure according to the laser energy and the application time. Methods The implant surface was irradiated by Er:YAG laser under combination condition using the laser energy of 100 mJ/pulse, 140 mJ/pulse and 180 mJ/pulse and application time of 1 minute, 1.5 minutes and 2 minutes. The specimens were exam...

  1. Stable single-mode operation of injection-seeded Q-switched Nd:YAG laser by sine voltage modulation

    Yongfei Gao; Junxuan Zhang; Huaguo Zang; Xiaolei Zhu; Yingjie Yu; Weibiao Chen


    Based on the modified ramp and fire technique,a novel injection seeding approach with real-time resonance tracking is successfully demonstrated in a single-frequency Nd:YAG pulsed laser.Appling a high-frequency sinusoidal modulation voltage to one piezo actuator and an adjustable DC voltage to another piezo actuator for active feedback,single-mode laser output with high-frequency stability is obtained,and the effect of the piezo hysteresis on the frequency stability can be eliminated for a laser diode pumped Q-switched Nd:YAG laser at a repetition rate of 400 Hz.

  2. Shear test of composite bonded to dentin: Er:YAG laser versus dental handpiece preparations

    Visuri, Steven R.; Gilbert, Jeremy L.; Walsh, Joseph T., Jr.; Wigdor, Harvey A.


    The erbium:YAG laser coupled with a cooling stream of water appears to be an effective means of removing dental hard tissues. However, before the procedure is deemed clinically viable, there are several important issues of safety and efficacy that need to be explored. In this study we investigated the surface that remains following laser ablation of dentin and compared the results to the use of a dental handpiece. Specifically, we studied the effect the laser radiation had on the bonding of composite to dentin. The crowns of extracted human molars were removed revealing the underlying dentin. An additional thickness of material was removed with either a dental handpiece or an Er:YAG laser by raster scanning the samples under a fixed handpiece or laser. Comparable surface roughnesses were achieved. A cylinder of composite was bonded onto the prepared surfaces following the manufacturer's directions. The dentin-composite bond was then shear stressed to failure on a universal testing apparatus and the maximum load recorded. Preliminary results indicated that laser irradiated samples had improved bond strengths. SEM photographs of the surfaces were also taken to compare the two methods of tooth preparation.

  3. Ultrasound-guided interstitial Nd:YAG laser therapy of cavernous hemangiomas

    Hoffmann, Peter; Offergeld, Christian F.; Huettenbrink, Karl-Bernd; Hackert, I.; Scholz, A.


    Preoperative embolization and excision used to be standard therapy amongst a wide range of other more or less successful methods for the treatment of voluminous hemangiomas. Nowadays a combination of argon, tunable dye, copper vapor and Nd:YAG laser therapy achieves better cosmetic and functional results. Due to its limited penetration depth percutaneous laser therapy can only be utilized for superficial vascular malformations. Interstitial laser therapy, as performed with the Nd:YAG laser, allows treatment of voluminous hemangiomas in their full extent. The localization of these vascular lesions is evaluated by high resolution ultrasound with a new anular array scanner which ensures the precise intraoperative placement of the laser light fiber in the target tissue. Modified new light applicators improve the interstitial thermotherapy of hemangiomas. The tip design of the scattering-dome fiber allows diffuse circumferential irradiation with larger defined coagulation volume and minimized carbonization. Continuous intraoperative sonographic monitoring lowers the risk of damaging adjacent intact anatomical structures, helps to reach all tumor areas an to estimate the effect of the applied laser light caused by changes of sonomorphology. The postoperative outcome is evaluated by B-mode sonography and the new technique of ultrasound color angiography.

  4. Removal of graffiti from the mortar by using Q-switched Nd:YAG laser

    Sanjeevan, Poologanathan; Klemm, Agnieszka J.; Klemm, Piotr


    This paper presents part of the larger study on microstructural features of mortars and it's effects on laser cleaning process. It focuses on the influence of surface roughness, porosity and moisture content of mortars on the removal of graffiti by Nd:YAG laser. The properties of this laser are as follows: wavelength ( λ) 1.06 μm, energy: 500 mJ per pulse, pulse duration: 10 ns. The investigation shows that the variation of laser fluence with the number of pulses required for the laser cleaning can be divided into two zones, namely effective zone and ineffective zone. There is a linear relationship observed between number of pulses required for laser cleaning and the laser fluence in the effective zone, while the number of pulses required for the laser cleaning is almost constant even though the laser fluence increases in the ineffective zone. Moreover, surface roughness, porosity and moisture content of mortar samples have influence on the laser cleaning process. The effect of these parameters become however negligible at the high level of laser fluence. The number of pulses required for the laser cleaning is low for smooth surface or less porous mortar. Furthermore, the wetness of the samples facilitates the cleaning process.

  5. Experimental investigation on cleaning of corroded ancient coins using a Nd:YAG laser

    Zhu, Huazhong; Lu, Jian; Ni, Xiaowu; Shen, Zhonghua


    The objective of the work reported is to study experimentally on the removal of corrosion layer from the ancient coins using laser beam as the conservation tool. With the use of Q-switched Nd:YAG laser radiation at 1064 nm, dry laser cleaning, steam laser cleaning and chemical-assisted laser cleaning were used to find out a more suitable and efficient laser treatment for corrosion removal. Cleaning tests were performed on ancient Chinese coins. Experimental results shows that the dry laser cleaning was not successful at removing all types of corrosion crust. It was possible to remove the outer thicker layer of the corrosion products (typically known as patina), but failed on the thinner layer of cuprite. The steam laser cleaning could decrease the initial removal threshold and improve the removal efficiency especially for the oxidation with powdery structure. As for chemical-assisted laser treatment, the cleaning results demonstrate that the combination of laser and chemical reagent could provide a considerable improvement in corrosion removal compared with the conventional laser treatments. Most of the corrosion contaminant was stripped, even the cuprite layer. Moreover, no secondary pollution was formed on the cleaned surface. X-ray fluorescence was applied to determine the variation of composition of surface layer and bulk metal before and after the coins cleaned. It shows that all of the three laser treatments were efficient to reduce the chlorine concentration on the surface of the coins more than 75%.

  6. Marginal microleakage in vitro study of occlusal fissures sealing prepared and etched or not with Er: YAG laser; Avaliacao in vitro da microinfiltracao marginal em selamentos oclusais preparados e condicionados ou nao pelo laser de Er:YAG

    Youssef, Fernanda de Almeida


    The aim of this in vitro study was to evaluate the degree of marginal microleakage in occlusal sealing by invasive techniques, after preparation with Er:YAG laser followed or not by Er:YAG laser etching and compared to the conventional technique. Thirty human premolars were divided into three groups: A (control group) - cavities were prepared with high speed and etched with 37% orthophosphoric acid; group B - cavities were prepared with Er:YAG (350 mJ, 4 Hz and 112 J /cm{sup 2}) and etched with 37% orthophosphoric acid; group C - cavities were prepared with Er:YAG laser (350 mJ, 4 Hz and 112 J/cm{sup 2}), and etched with Er:YAG laser (80 mJ, 4 Hz and 25 m/cm{sup 2}). All cavities were treated with the same adhesive system and restored with flow composite according to manufacturer instructions. Teeth were submitted to thermal cycling procedures and immersed in 50% Silver Nitrate Solutions for 8 hours in total darkness. Teeth were sectioned longitudinally in the bucco-lingual direction, in slices of 1 mm thick. Each slice was immersed into photo developing solution under 16 hours of fluorescent light. Slices were photographed and microleakage was scored from 0 to 7 J by three standard examiners. Results showed statistically significant differences for group C (Er:YAG laser preparation and etching). We concluded that Er:YAG laser can be used for cavity preparation of occlusal sealing, like the conventional high speed method. However, this laser, used as enamel etching agent, could not promote an adequate surface for adhesive procedures. (author)

  7. Radially polarized and passively Q-switched Nd:YAG laser with composite structure of gain medium

    Kegui Xia; Jianlang Li


    We report on a radially polarized and passively Q-switched Nd:YAG/Cr4+:YAG laser.The bulk Nd:YAG crystal is bonded with two undoped YAG crystal end caps to weaken the thermal lens effect and thus,enhance the extraction of stored energy in the bulk gain material.In the absence of active water cooling,the average laser power reaches 383 mW with 33% slope efficiency,and the laser pulse achieves 1.457-W peak power,18.9-ns duration,and 13.9-kHz repetition rate with 97.6% polarization purity.The radially polarized laser beam shows axial symmetry both in amplitude and polarization[1-3].The beam is applied in a variety of fields[3-8] such as particle trapping and acceleration[5],high-resolution microscopy[6],and material processing (e.g.,metal cutting or drilling).Because radially polarized light is globally of the ptype with respect to the cutting surface,the material absorption to the irradiation could be maximized,the significant effect of the cutting depth and cutting speed can be facilitated[7,8].This advantage has created a high demand for high power and radially polarized lasers.%We report on a radially polarized and passively Q-switched Nd:YAG/Cr4+:YAG laser. The bulk Nd:YAC crystal is bonded with two undoped YAG crystal end caps to weaken the thermal lens effect and thus, enhance the extraction of stored energy in the bulk gain material. In the absence of active water cooling, the average laser power reaches 383 mW with 33% slope efficiency, and the laser pulse achieves 1.457-W peak power, 18.9-ns duration, and 13.9-kHz repetition rate with 97.6% polarization purity.

  8. Investigation of lasing characteristics of domestic Yb : YAG laser ceramics

    Snetkov, I. L.; Palashov, O. V.; Osipov, V. V.; Mukhin, I. B.; Maksimov, R. N.; Shitov, V. A.; Luk'yashin, K. E.


    We report on the synthesis and laser characteristics of Yb3+-doped yttrium aluminium garnet (Y3Al5O12) optical ceramics. The ceramics was produced by solid-phase reactive sintering of a mixture of Yb (5 at %) : Y2O3 and Al2O3 nanopowders synthesised by laser ablation, using additional calcination of the mixture before compaction. In a thin disk geometry, multiwatt laser oscillation was obtained at a wavelength of 1030 nm with a power of 5.2 W and a slope efficiency of 37.0% at a pump pulse period-toduration ratio of 5.72.

  9. Comparison of Dentin Permeability After Tooth Cavity Preparation with Diamond Bur and Er:YAG Laser

    Masoumeh Hasani Tabatabaei


    Full Text Available Objectives: The aim of this study was to compare the permeability of dentin after using diamond bur and Er:YAG laser.Materials and Methods: Seventy-two recently extracted, intact, and restoration-free human permanent molars were used in this study. The samples were randomly divided into three groups of 24 each and class I cavities were prepared as follows. Group 1: High speed diamond bur with air and water spray. Group 2: Er:YAG laser. Group 3: Er:YAG laser followed by additional sub-ablative laser treatment. Each group consisted of two subgroups with different cavity depths of 2mm and 4mm.  The entire cavity floor was in dentin. Two samples from each subgroup were observed under scanning electron microscope (SEM. The external surfaces of other samples were covered with nail varnish (except the prepared cavity and immersed in 0.5% methylene blue solution for 48 hours.  After irrigation of samples with water, they were sectioned in bucco-lingual direction. Then, the samples were evaluated under a stereomicroscope at ×160 magnification. The data were analyzed using two-way ANOVA and Tukey’s HSD test.Results: Two-way ANOVA showed significant difference in permeability between groups 2 and 3 (laser groups with and without further treatment and group 1 (bur group. The highest permeability was seen in the group 1. There was no significant difference in dentin permeability between groups 2 and 3 and no significant difference was observed between different depths (2mm and 4mm.Conclusion: Cavities prepared by laser have less dentin permeability than cavities prepared by diamond bur.


    王立清; 胡盛涛; 李澎; 谢峰; 吴清玉; 郭加强


    Objective. To study the mechanism and effects of blood perfusion to the acute ischemic region of myecardium through Ho-YAG laser channels with myocardial contrast echocardiography Methods. To produce the model of acute myocardial ischemia, we partially ligated the left anterior decending (IAD)coromry artery of canine hearts between 1st. and 2nd. diagonal branches and then performed transmyocardial revasmgafizafion in this region with Ho- YAG laser. Myocardial contrast echecardingmphy was made with a new gen-eration of ultrasound contrast agent and second harmonic imaging of this region before,after ischemia and after laser revascalarizafion. Pictures were taken with “R” wave trigger skill. Results. Acoustic demity derterming in the ischemia region (anterior wall)with MCE(myocardial contrast e-checardiography) was obviously decreased(5.40 ± 1.81) after the LAD was ligated,as compared with before( 11.69± 1.61, P 0.05). There were no dif-ferences in acoustic density in the lateral wall(as control)among these comprehensive three periods (P > 0.05). Con-trast in the laser region developed one cardiac cycle ahead of that in the non-iscbemic normal region. Conclusion. Acute ischemic myecardium can be perfused by oxygenated blood from the left ventricle through Ho-YAG laser channels. Evidenee of blood perfusion through laser channels during systolic phase was detected,and my-ocardial cormast ultrasonngtaphy using intravenous perfluorocarbon-exposed sonicated dextrose albumin may be regard-ed as a reliable method in the study of tranmlyecardial revasculariztion.

  11. Continuous 1052, 1064 nm dual-wavelength Nd:YAG laser

    Wang, Xiaozhong; Yuan, Haiyang; Wang, Mingshan; Huang, Wencai


    Dual-wavelength lasers are usually obtained through balancing the net gain of the two oscillating lines. Competition between transitions 1052 nm, 1061 nm and 1064 nm is utilized to realize a continuous wave 1052 and 1064 nm dual-wavelength Nd:YAG laser firstly in this paper. A specially designed Fabry-Perot band-pass filter is exploited as output coupler to control the thresholds of the oscillating wavelengths. The maximum power of the dual-wavelength laser is 1.6 W and the slope efficiency is about 10%. The power instability of the output dual-wavelength laser is smaller than ±4% in half an hour. The mechanism presented in this paper may provide a new way to obtain dual-wavelength lasers.

  12. Microstructural and Hardness Study of Pulsed Nd:YAG Laser Surface Alloyed Aluminum with Iron

    Ansari, Mohammad; Soltani, Reza; Heydarzadeh Sohi, Mahmoud; Valefi, Zia


    In the present study, the feasibility of the formation of surface layers containing hard iron aluminides on AA6061-T6 aluminum via pre-plasma spraying with iron and subsequently double surface melting by pulsed Nd:YAG laser is studied. The effects of single and double laser surface melting on microstructure, phase formation, and hardness of the treated layers are examined. Single-step laser treatment resulted in the presence of undissolved iron particles surrounded by lump-like Al5Fe2 and needle-like Al3Fe intermetallic compounds. Double laser surface melting dissolved the retained undissolved irons and resulted in the formation of Al-Al3Fe eutectic structure. Microhardness profiles along cross section and top surface of the treated layers indicated that laser surface alloying with iron enhanced the hardness of the aluminum to more than twice of that of the base material.

  13. Simultaneous Q-switching and mode-locking in the CW Nd:YAG laser

    Kuizenga, D. J.; Phillion, D. W.; Siegman, A. E.; Lund, T.


    The theory of transient mode-locking for an active modulator in a laser with a homogeneously broadened line is presented. The theory is applied to simultaneously Q-switched and mode-locked Nd:YAG lasers and good agreement between theory and experiment is obtained. The main conclusion is that under usual Q-switched operating conditions the mode-locking process does not have sufficient time to build up to steady-state conditions. We also present a method to overcome this problem by allowing the laser to prelase before the Q-switch is opened. Mode-locked pulses whose width approaches the steady-state value are obtained. The transient mode-locking theory presented here also applies to actively mode-locking TEA CO2 lasers and to other types of simultaneously pulsed and mode-locked lasers.

  14. Dynamics of Efficiency Change by Temperature in Diode Pumped Nd:YAG Heat Capacity Laser

    WANG Xiao-Jun; TANG Bing; SHU Xiao-Jian


    We investigate the influence of temperature on the efficiency of diode pumped Nd:YAG heat capacity laser is studied. It is shown that the efficiency of such a laser system is greatly reduced at higher temperature. This bad behaviour is mainly caused by the doped-ion redistribution among various Stark levels of the ground state, and by a thermal equilibrium between the upper laser level and the pump level. Meanwhile, the thermal excitations from the ground state to the lower laser level also play a role. We derive a model to describe those effects, with the considerations of emission spectrum of laser diodes, the subtle Stark structures and the linewidth of absorption and of simulated-emission.

  15. Assessing microleakage of composite restorations in class V cavities prepared by Er:YAG laser irradiation or diamond bur

    Sakineh Arami


    Full Text Available Introduction: The aim of this study was to make a comparison between microleakage of conventionally restored class V cavities using bur and acid etchant and, the ones prepared and conditioned by Er:YAG laser. Materials and Methods: 30 recently extracted intact caries and filling free human permanent molars were used for this study. Then, Cold cure acrylic resin was used to seal the apices. The samples were randomly assigned to 5 groups of six each. Class V cavities were prepared one on buccal and one on lingual surface of each sample. Group 1: cavity preparation by diamond bur and turbine + acid etch, Group 2: cavity preparation by Er:YAG laser + acid etch, Group 3: cavity preparation by Er:YAG laser + Laser etching, Group 4: cavity preparation by diamond bur and turbine + laser etching, Group 5: cavity preparation by Er:YAG laser with no conditioning procedure. The cavities restored with restorative composite resin. Samples were then immersed in 2% methylene blue solution for 24 hours. The data were then analyzed using Wilcoxon signed ranks test and Kruskal-Wallis statistical tests. Results: The Kruskal Wallis test showed a significant difference (P < 0.05 between enamel and cementum margin microleakage, while the higher microleakage was related to the cementum margin of restorations. Conclusion: There was no significant difference in evaluating microleakeage degree of cavities prepared by Er:YAG laser and diamond bur.

  16. Nd:YAG Laser-aided ceramic brackets debonding: Effects on shear bond strength and enamel surface

    Han Xianglong [State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610041 (China); Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Liu Xiaolin [Department of Orthodontics, Stomatology Hospital, Dalian University, Dalian 116021 (China); Bai Ding [State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610041 (China); Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China)], E-mail:; Meng Yao; Huang Lan [Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China)


    In order to evaluate the efficiency of Nd:YAG laser-aided ceramic brackets debonding technique, both ceramic brackets and metallic brackets were bonded with orthodontic adhesive to 30 freshly extracted premolars. The specimens were divided into three groups, 10 in each, according to the brackets employed and the debonding techniques used: (1) metallic brackets with shear debonding force, (2) ceramic brackets with shear debonding force, and (3) ceramic brackets with Nd:YAG laser irradiation. The result showed that laser irradiation could diminish shear bond strength (SBS) significantly and produce the most desired ARI scores. Moreover, scanning electron microscopy investigation displayed that laser-aided technique induced little enamel scratch or loss. It was concluded that Nd:YAG laser could facilitate the debonding of ceramic brackets and diminish the amount of remnant adhesive without damaging enamel structure.

  17. Nd:YAG Laser-aided ceramic brackets debonding: Effects on shear bond strength and enamel surface

    Han, Xianglong; Liu, Xiaolin; Bai, Ding; Meng, Yao; Huang, Lan


    In order to evaluate the efficiency of Nd:YAG laser-aided ceramic brackets debonding technique, both ceramic brackets and metallic brackets were bonded with orthodontic adhesive to 30 freshly extracted premolars. The specimens were divided into three groups, 10 in each, according to the brackets employed and the debonding techniques used: (1) metallic brackets with shear debonding force, (2) ceramic brackets with shear debonding force, and (3) ceramic brackets with Nd:YAG laser irradiation. The result showed that laser irradiation could diminish shear bond strength (SBS) significantly and produce the most desired ARI scores. Moreover, scanning electron microscopy investigation displayed that laser-aided technique induced little enamel scratch or loss. It was concluded that Nd:YAG laser could facilitate the debonding of ceramic brackets and diminish the amount of remnant adhesive without damaging enamel structure.

  18. Effective shortening of picosecond pulses emitted by a YAG:Nd/sup 3 +/ laser

    Dianov, E.M.; Karasik, A.Y.; Mamyshev, P.V.; Onishchukov, G.I.; Prokhorov, A.M.; Stel' makh, M.F.; Fomichev, A.A.


    A 15-fold reduction in the duration of YAG:Nd/sup 3 +/ laser pulses was achieved under conditions of active mode locking and Q switching at a pulse repetition frequency approx.1 kHz. Phase self-modulation in a single-mode quartz fiber waveguide of length 10 m resulted in broadening of the laser emission spectrum right up to approx.10 cm/sup -1/ at the waveguide exit. The pulses were then shortened in a system with a diffraction grating. The pulse duration was measured by a correlation system in which the second harmonic was generated.

  19. Vapor emissions resulting from Nd:YAG laser interaction with tooth structure.

    Gelskey, S C; White, J M; Gelskey, D E; Kremers, W


    The Neodymium:yttrium aluminum garnet (Nd:YAG) dental laser has been cleared by the United States Food and Drug Administration (FDA) for marketing in intraoral soft tissue treatment. The efficacy and safety of the Nd:YAG laser in the treatment of hard dental tissue as well as the effects of dental irradiation on the pulp and periodontium have been investigated. Odors resulting from laser irradiation have been reported, but the nature and toxicity of associated decomposition vapors is unknown and the health consequences of their inhalation have not yet been studied. The purpose of this in vitro study was to identify vapors emitted during interaction of the Nd:YAG laser with carious human enamel and dentin and sound enamel and dentin coated with organic ink. Vapor emissions were collected from prepared sections of extracted human teeth receiving laser irradiation of 100 mJ and 10 Hz for a duration of 1, 10, or 60 s. Emissions were collected by means of charcoal absorption tubes, and subsequently analyzed using a Gas Chromatograph equipped with Mass Selective (GC/MS) and Flame Ionization Detectors to identify the chemical constituents of the vapors. No compounds were identified in Nd:YAG laser-treated caries, enamel and dentin. No volatile vapors were identified from samples of tooth materials exposed to the laser for 1 or 10 s. Camphor was positively identified in the test sample which consisted of India ink-coated dentin and the reference sample of India ink-coated glass beads, both exposed to the laser for 60 s. 2,5-norbornadiene was tentatively identified in these samples. The Threshold Limit Value (TLV) of camphor is 2 ppm with a Lethal Dose Level (LDLo) of 50 mg/kg (human oral), while the TLV and LDLo of 2,5-norbornadiene is unknown. Occupational and public health safety measures are discussed in this article. Further research is needed to quantify the compounds produced and to determine their toxicity to patients and to dental care providers.

  20. Effect of Er:YAG laser on debonding strength of laminate veneers

    Iseri, Ufuk; Oztoprak, Mehmet Oguz; Ozkurt, Zeynep; Kazazoglu, Ender; Arun, Tulin


    Objective: The purpose of this study was to evaluate the debonding strength of laminate veneers after using erbium-doped: yttrium aluminium garnet (Er:YAG) laser. Materials and Methods: A total of 60 bovine mandibular incisor teeth were divided into two groups (n = 30). Cylindrical specimens (0.7 mm × 5 mm) were fabricated from Empress II ceramic. Then, they were cemented to incisors using dual-cured resin cement (Variolink II). In the first group, no laser application was performed. The Er:Y...

  1. Regenerative amplification and bifurcations in a burst-mode Nd:YAG laser.

    Mance, Jason G; Slipchenko, Mikhail N; Roy, Sukesh


    An Nd:YAG-based burst-mode regenerative amplifier laser was developed that offers high extraction efficiency at high repetition rates with low seed energies. The regenerative amplification technique, combined with the burst-mode laser technology, shows promise as an efficient method for amplification of femtojoule-nanojoule pulses up to millijoule energies at repetition rates exceeding 100 kHz. Output energies at repetition rates near the inverse upper state lifetime are limited by bifurcations in the pulse energies of the burst. A model is developed and advantages and limitations are discussed.

  2. Nd:YAG laser induced E' centers probed by in situ absorption measurements

    Cannas, M.; Messina, F.


    We investigated various types of commercial silica irradiated with a pulsed Nd:YAG laser radiation (4.66 eV), with exposure time ranging up to 10000 s. Transient E' centers were probed in situ by measuring the amplitude of the optical absorption band at 5.8 eV (due to E' centers) both during and after irradiation. The laser-induced absorption is observed only in natural samples, whereas the synthetic materials exhibit high toughness to radiation effect. The reported results evidence that the ...

  3. Diffractive optics for reduction of hot cracking in pulsed mode Nd:YAG laser welding

    Bagger, Claus; Olesen, Søren; Roos, Sven-Olov


    In order to reduce the susceptibility to hot cracking in pulsed mode laser welding of austenitic stainless steel, an optical system for reduction of the cooling rate is sought developed. Based on intensive numerical simulations, an optical system producing three focused spots is made. In a number...... of systematic tests, the applicability of this system is tested on an industrial 1 kW Nd:YAG laser. Three separate series of tests are conducted, one with the diffractive optical system at 500 W and two without the diffractive system at 400 W and 500 W, respectively. In principle the diffractive, optical system...

  4. 550-W diode-pumped Nd:YAG disk laser

    Zhenyu Yao; Jianfeng Jiang; Bo Tu; Tangjian Zhou; Lingling Cui


    When a thin laser crystal disk is used with a nearly flat-top pump profile, the heat flux can be considered to be one-dimensional. This results in a homogeneous temperature and stress profile within the laser medium leading to reduction of thermal effects. A nearly flat-top pump profile is achieved with a two-pass cylindrical-lens coupling system. An average output power of 550 W is obtained by an average pumping

  5. High Efficient Continuous-Wave Ho: YAG Laser Pumped by a Diode-pumped Tm: YLF Laser at Room Temperature

    DUAN Xiao-Ming; YAO Bao-Quan; ZHANG Yun-Jun; SONG Cheng-Wei; GAO Jing; JU You-Lun; WANG Yue-Zhu


    We present a high efficient continuous wave Ho:YAG laser pumped by a diode-pumped Tm:YLF laser with a Fabry-Perot etalon tuning at 1.91 μm. The maximum output power reaches 7.2 W when the absorbed pump power is 10.8 W.The slope efficiency (relative to the absorbed power) is 74.1%,and the Tm:YLF to Ho:YAG optical conversion efficiency of 60%,then the diode-to-Holmium optical conversion efficiency achieved is 21.0%.The wavelength is 2090 nm when the transmission of output coupler is larger than 20%.The beam quality factor is M2 ~ 1.15 measured by the travelling knife-edge method.

  6. Efficient second harmonics generation of a laser-diode-pumped Nd:YAG laser and its applications. Laser diode reiki Nd:YAG laser no kokoritsu daini kochoha hassei to sono oyo

    Kubota, S.; Oka, M. (Sony Corp., Tokyo (Japan))


    Stabilization of the second harmonics in a laser-diode-pumped Nd:YAG laser and its application are described. The laser is a quantum noise limiting laser, in which a mode competing noise is generated from an interaction between the laser medium Nd:YAG and the type II nonlinear optical crystal KTiOPO{sub 4} when generating a second harmonics in the resonator. However, the quantum noise limiting second harmonics was obtained by means of inserting (1/4) wave length plate in the resonator to release the bond between two intersecting inherent polarization modes. This stabilized green laser is of a single lateral mode is nearly free of aberration. Therefore, an optical disc prototype having three times as much of the currently used density was made using an objective lens having high number of openings to collect lights, which was verified capable of regeneration at a high signal to noise ratio. In addition, higher output is possible by means of parallelizing the excitation, and high output is realized from edge excitation at a fiber bundle. 18 refs., 3 figs.

  7. Water content contribution in calculus phantom ablation during Q-switched Tm:YAG laser lithotripsy.

    Zhang, Jian J; Rajabhandharaks, Danop; Xuan, Jason Rongwei; Wang, Hui; Chia, Ray W J; Hasenberg, Tom; Kang, Hyun Wook


    Q-switched (QS) Tm:YAG laser ablation mechanisms on urinary calculi are still unclear to researchers. Here, dependence of water content in calculus phantom on calculus ablation performance was investigated. White gypsum cement was used as a calculus phantom model. The calculus phantoms were ablated by a total 3-J laser pulse exposure (20 mJ, 100 Hz, 1.5 s) and contact mode with N=15 sample size. Ablation volume was obtained on average 0.079, 0.122, and 0.391  mm3 in dry calculus in air, wet calculus in air, and wet calculus in-water groups, respectively. There were three proposed ablation mechanisms that could explain the effect of water content in calculus phantom on calculus ablation performance, including shock wave due to laser pulse injection and bubble collapse, spallation, and microexplosion. Increased absorption coefficient of wet calculus can cause stronger spallation process compared with that caused by dry calculus; as a result, higher calculus ablation was observed in both wet calculus in air and wet calculus in water. The test result also indicates that the shock waves generated by short laser pulse under the in-water condition have great impact on the ablation volume by Tm:YAG QS laser.

  8. Comparative study of microstructural characteristics of electrospark and Nd:YAG laser epitaxially growing coatings

    Xie, Yu-jiang; Wang, Mao-cai; Huang, Da-wei


    As low-heat input welding processes, electrospark deposition and pulsed Nd:YAG laser cladding can be commonly used to prepare epitaxially growing coatings. However, these two processes have quite different characteristics in the energy input, the amount of materials involved, and the temperature gradient, and hence might result in dissimilar microstructural characteristics. In this paper, a comparative study has been made between microstructural characteristics in epitaxial growth coatings prepared by electrospark deposition and pulsed Nd:YAG laser cladding. Some interesting results have been achieved. Firstly, epitaxial growth coatings can be commonly achieved by these two techniques. Secondly, microstructural morphologies of these two epitaxial growth coatings are obviously different, cellular columnar structure prevails in the electrospark coating while columnar dendritic structure occupies most of the laser coating thickness, more importantly, electrospark coating remains fully columnar in the whole layer whereas laser coating tends to change from columnar to equiaxed at the top of the layer. Thirdly, electrospark coating possesses finer and more homogeneous microstructure than laser coating.

  9. Surface Profiling Of Paper Radiated With Focused Infra-Red Nd:yag Pulsed Laser

    Ahmad Hadi Ali


    Full Text Available A Nd:YAG pulsed laser with wavelength of 1.06 mm can cause a tremendous damage when interacts with material. In this study the effects of Nd:YAG laser interactions onto paper are reported. A combination lens technique was used with different focal length of lens. The target material that is a photographic paper was positioned at a focal spot of the laser beam. IR laser pulsed with peak power up to megawatt (MW is brought to focus thus interacts with the photographic paper. This high-power impact of the laser pulsed shockwave caused a tremendeous damage on the photographic paper. Measurement of the impact was base on the surface size of the damage. From the observation result it shows that the maximum damage diameter for short lens system is 0.613 mm at peak power of 21.93 MW, whereas the maximum damage diameter for long lens system is 1.224 mm at 22.25 MW peak power.

  10. Single-mode, All-Solid-State Nd:YAG Laser Pumped UV Converter

    Prasad, Narasimha S.; Armstrong, Darrell, J.; Edwards, William C.; Singh, Upendra N.


    In this paper, the status of a high-energy, all solid-state Nd:YAG laser pumped nonlinear optics based UV converter development is discussed. The high-energy UV transmitter technology is being developed for ozone sensing applications from space based platforms using differential lidar technique. The goal is to generate greater than 200 mJ/pulse with 10-50 Hz PRF at wavelengths of 308 nm and 320 nm. A diode-pumped, all-solid-state and single longitudinal mode Nd:YAG laser designed to provide conductively cooled operation at 1064 nm has been built and tested. Currently, this pump laser provides an output pulse energy of >1 J/pulse at 50 Hz PRF and a pulsewidth of 22 ns with an electrical-to-optical system efficiency of greater than 7% and a M(sup 2) value of <2. The single frequency UV converter arrangement basically consists of an IR Optical Parametric Oscillator (OPO) and a Sum Frequency Generator (SFG) setups that are pumped by 532 nm wavelength obtained via Second Harmonic Generation (SHG). In this paper, the operation of an inter cavity SFG with CW laser seeding scheme generating 320 nm wavelength is presented. Efforts are underway to improve conversion efficiency of this mJ class UV converter by modifying the spatial beam profile of the pump laser.

  11. [Gingival depigmentation for aesthetic purposes using erbium:YAG laser: rationale and technique].

    Tal, H; Oelgiessr, D; Tal, M


    Melanin, carotene and hemoglobin are the most common natural pigments contributing to the normal color of the gums. Although physiologic and ethnic melanin pigmentation is not a medical problem, complains about "black gums" are common. Gingival depigmentation has been carried out using surgical, chemical, electrosurgical and cryosurgical procedures. Recently, Laser Ablation has been recognized as one of the most effective, pleasant and reliable techniques. Effective depigmentation of the gingival requires removal of all or most of the melanocytes from the basal layer of the gingival epithelium. Using non-specific radiation means ablation of all the epithelial cell layers, as well as connective tissue rete pegs, leaving behind only remnants of the epithelial rete ridges. CO2, Nd:YAG and Erbium:YAG lasers, meeting most of these requirements and being available in the dental office, seems to be the lasers of choice for this procedure. Five patients (3 F; 2 M) who were referred to the TAUSDM for cosmetic therapy of "black gums" were treated using Erbium-YAG laser. The laser beam was set up at 850 mj/10 pulses per second producing peak power of 2.13 kwand peak power density of 30.43 kw/sq/cm. The beam was defocused to produce a 3 mm diameter circle, thus reducing the beam penetration while increasing the treated surface. Using the "brush" technique, 800-2,000 pulses were required per patient, with an average of 500-1,100 pulses per 1, depending on the thickness of the epithelium and the intensity of the pigmentation. Treatment required only topical anesthesia. Healing was uneventful and required no supportive therapy. Three months follow up has shown no repigmentation in any of the patients. Patients' evaluation analysis showed that the results were pleasing; no pain was experienced during lasing as well as during healing. Two patients were interupted by the lasing burning smell, which may be reduced or eliminated by operating a power suction during the procedure.

  12. Cellulite: a new treatment approach combining subdermal Nd: YAG laser lipolysis and autologous fat transplantation.

    Goldman, Alberto; Gotkin, Robert H; Sarnoff, Deborah S; Prati, Clarissa; Rossato, Flávia


    Cellulite is an alteration of the topography of the skin that occurs in body areas where fat deposition seems to be under the influence of estrogen: mainly the hips, buttocks, thighs, and abdomen. The presence of cellulite is a significant source of patient dissatisfaction. There is currently no cure or consistently effective treatment for cellulite. The authors sought to show that the subdermal application of the neodymium-doped yttrium aluminium garnet (Nd:YAG) laser combined with autologous fat transplantation is a safe and effective treatment for cellulite. From January 2003 to December 2006, 52 female patients with Curri grade III to IV cellulite were treated with subdermal 1064-nm Nd:YAG laser lipolysis combined with autologous fat transplantation. Patient assessment was collected for data analysis. After the treatment, tissue samples were obtained in some subjects in order to ascertain the histologic effects of the laser treatment. This treatment resulted in significant clinical improvement in cellulite. The adverse effects were mild and temporary, and the postoperative period was well tolerated. A majority of patients (84.6%) rated the results of treatment as either good or excellent. The treatment of severe cases of cellulite (Curri grades III and IV) by a combination of 1064-nm Nd:YAG laser lipolysis and autologous fat transplantation proved to be both safe and effective. In addition, subdermal laser lipolysis has the advantage of inducing neocollagenesis and stimulating postoperative skin tightening. This represents a new treatment option for the ubiquitous cellulite disorder. Although this treatment has shown promising results in this pilot study, further studies are necessary in order to draw final conclusions.

  13. Temperature-related performance of Yb3+:YAG disc lasers and optimum design for diamond cooling

    Cao Ding-Xiang; Yu Hai-Wu; Zheng Wan-Guo; He Shao-Bo; Wang Xiao-Feng


    In this paper the temperature-related performances of the Yb3+:YAG disc laser has been investigated based on quasi-three level rate equation model. A compact diamond window cooling scheme also has been demonstrated. In this cooling scheme, laser disc is placed between two thin discs of single crystal synthetic diamond, the heat transfer from Yb3+:YAG to the diamond, in the direction of the optical axis, and then rapidly conducted radically outward through the diamond to the cooling water at the circumference of the diamond/Yb3+ :YAG assembly. Simulation results show that increasing the thickness of the diamond and the overlap-length (between diamond and water) decreases the disc temperature. Therefore a 0.3-0.5 mm thick diamond window with the overlap-length of 1.5-2.0 mm will provide acceptable cost effective cooling, e.g., with a pump intensity of 15 kW/cm2 and repetitive rate of 10 Hz, to keep the maximum temperature of the lasing disc below a reasonable value (310K), the heat exchange coefficient of water should be about 3000 W/m2K.

  14. Optical spectroscopy in channel waveguides made in Nd:YAG crystals by femtosecond laser writing

    Torchia, G.A. [Grupo de Optica, Departamento de Fisica Aplicada, Universidad de Salamanca, Plaza de la Merced s/n, 37008 Salamanca (Spain); Centro de Investigaciones Opticas (CIOp), CIC-Conicet, CC 124 La Plata (1900) (Argentina)], E-mail:; Mendez, C.; Roso, L. [Grupo de Optica, Departamento de Fisica Aplicada, Universidad de Salamanca, Plaza de la Merced s/n, 37008 Salamanca (Spain); Tocho, J.O. [Centro de Investigaciones Opticas (CIOp), CIC-Conicet, CC 124 La Plata (1900) (Argentina)


    In this work, we present an optical characterization of channel waveguides fabricated by means of femtosecond laser writing on Nd:YAG substrates. These guiding structures show a refractive index increment of about 1x10{sup -3} which allows TE propagation. By pumping with a CW solid-state laser at 532 nm reaching the {sup 2}G{sub 9/2} and {sup 4}G{sub 7/2} manifolds of Nd{sup 3+} ions, we have explored the emission band corresponding to {sup 4}F{sub 3/2}{yields}{sup 4}I{sub 9/2} optical transitions (peaked at 890 nm). From data, we have found that emission showed similar characteristics for waveguide and bulk. On the other hand, the lifetime corresponding to the {sup 4}F{sub 3/2} metaestable level was determined to be 240 {mu}s for bulk and waveguide. Summarizing, we have made suitable channel waveguides in Nd:YAG crystals, by fs interaction, with similar spectroscopic properties to those of the bulk, a fact that boosters the photonics application of these devices. For the first time to our knowledge, a direct index increment waveguide made by interaction with ultra-short intense pulses in YAG crystals has been performed. This fabrication procedure can be an efficient tool to make several optical circuits in active materials by means of the one-step, fast and low-cost processing.

  15. Performance study of highly efficient 520 W average power long pulse ceramic Nd:YAG rod laser

    Choubey, Ambar; Vishwakarma, S. C.; Ali, Sabir; Jain, R. K.; Upadhyaya, B. N.; Oak, S. M.


    We report the performance study of a 2% atomic doped ceramic Nd:YAG rod for long pulse laser operation in the millisecond regime with pulse duration in the range of 0.5-20 ms. A maximum average output power of 520 W with 180 J maximum pulse energy has been achieved with a slope efficiency of 5.4% using a dual rod configuration, which is the highest for typical lamp pumped ceramic Nd:YAG lasers. The laser output characteristics of the ceramic Nd:YAG rod were revealed to be nearly equivalent or superior to those of high-quality single crystal Nd:YAG rod. The laser pump chamber and resonator were designed and optimized to achieve a high efficiency and good beam quality with a beam parameter product of 16 mm mrad (M2˜47). The laser output beam was efficiently coupled through a 400 μm core diameter optical fiber with 90% overall transmission efficiency. This ceramic Nd:YAG laser will be useful for various material processing applications in industry.

  16. The use of ultraviolet Thomson scattering as a versatile diagnostic for detailed measurements of a collisional laser produced plasma

    Tracy, M.D.


    Collective Thomson scattering from ion-acoustic waves at 266nm is used to obtain spatially resolved, two-dimensional electron density, sound speed, and radial drift profiles of a collisional laser plasma. An ultraviolet diagnostic wavelength minimizes the complicating effects of inverse bremsstrahlung and refractive turning in the coronal region of interest, where the electron densities approach n{sub c}/10. Laser plasmas of this type are important because they model some of the aspects of the plasmas found in high-gain laser-fusion pellets irradiated by long pulse widths where the laser light is absorbed mostly in the corona. The experimental results and LASNEX simulations agree within a percent standard deviation of 40% for the electron density and 50% for the sound speed and radial drift velocity. Thus it is shown that the hydrodynamics equations with classical coefficients and the numerical approximations in LASNEX are valid models of laser-heated, highly collisional plasmas. The versatility of Thomson scattering is expanded upon by extending existing theory with a Fokker-Planck based model to include plasmas that are characterized by (0 {le} k{sub ia}{lambda}{sub ii} {le} {infinity}) and ZT{sub e}/T{sub i}, where k{sub ia} is the ion- acoustic wave number, {lambda}{sub ii} is the ion-ion mean free path, Z is the ionization state of the plasma, and T{sub e}, T{sub i} are the electron and ion temperatures in electron volts respectively. The model is valid for plasmas in which the electrons are approximately collisionless, (k{sub ia}{lambda}{sub ei}, k{sub ia}{lambda}{sub ee} {ge} 1), and quasineutrality holds, ({alpha} {much_gt}1), where {alpha} = 1/k{lambda}{sub DE} and {lambda}{sub DE} is the electron Debye length. This newly developed model predicts the lineshape of the ion-acoustic Thomson spectra and when fit to experimental data provides a direct measurement of the relative thermal flow velocity between the electrons and ions.

  17. Fractional Carbon Dioxide, Long Pulse Nd:YAG and Pulsed Dye Laser in the Management of Keloids.

    Annabathula, Ashwini; Sekar, C Shanmuga; Srinivas, C R


    Keloids are abnormal wound responses characterised by excessive deposition of collagen and glycoprotein. They are both aesthetically and symptomatically distressing for most of the patients. There are reports of keloid management with pulsed dye laser (PDL), fractional carbon dioxide (CO2) laser and neodymium-doped yttrium aluminium garnet (Nd:YAG) laser individually and also in combination of CO2 with PDL and CO2 with Nd:YAG. Here, we discuss a combination of all the 3 lasers as a therapy for keloids. This study aims to assess the efficacy of fractional CO2 laser, long pulse Nd:YAG laser and PDL in the management of keloids. Fifteen patients with keloids were treated by fractional CO2 laser, followed by PDL and long pulse Nd:YAG laser at monthly intervals. Four patients discontinued the study and were lost for follow-up. Photographs were taken at the beginning of the treatment and at the end of five sessions. Clinical improvement was analysed based on a visual analogue scale graded by three blinded observers after assessing the clinical photographs for the improvement in size, colour and aesthetic impression. Of the 11 patients, one patient had excellent improvement, one patient had good improvement, four patients had moderate improvement, two patients had mild improvement and three had no improvement. Lasers may have a synergistic effect when combined with other modalities of treatment but cannot be used as monotherapy in the treatment of keloids.

  18. Preoperative Nd:YAG laser anterior capsulotomy in white intumescent cataracts: report of 11 cases Capsulotomia anterior pré-operatória com Nd:YAG laser em cataratas brancas intumescentes: relato de 11 casos

    Roberto Pinto Coelho


    Full Text Available Creating a continuous curvilinear capsulorhexis in eyes with white intumescent cataracts is a challenge due to the high risk of extension of capsular tears to the lens periphery. Several approaches have been described to avoid this complication and preoperative Nd:YAG laser anterior capsulotomy has been little reported as an optional technique. Eleven patients with white intumescent cataracts were submitted to preoperative Nd:YAG laser anterior capsulotomy. All patients had some degree of cortex falling in anterior chamber after laser application. No patient developed later complications. Thus, preoperative Nd:YAG laser anterior capsulotomy represents a safe and easy option for white intumescent cataracts.A realização da capsulorrexis curvilínea contínua em olhos com catarata branca intumescente é ainda considerada um desafio pelo alto risco de extensão da capsulotomia para a periferia do cristalino. Apesar da descrição de diversas técnicas cirúrgicas voltadas para a prevenção de tal complicação, o uso de Nd:YAG laser no pré-operatório tem raros relatos na literatura internacional. Onze pacientes com cataratas brancas intumescentes foram submetidos a capsulotomia pré-operatória com Nd:YAG laser. Todos os pacientes apresentaram, após a aplicação do laser, a saída de córtex liquefeito para a câmara anterior. Nenhum paciente apresentou complicações cirúrgicas com o procedimento. Desta forma, a capsulotomia anterior com Nd:YAG laser representa uma opção técnica fácil e segura no manejo de cataratas brancas intumescentes.

  19. Longitudinal Effect of Surface Treatments Modified by NaOCl-Induced Deproteinization and Nd:YAG Laser on Dentin Permeability.

    Esteves, Stella Renata Machado Silva; Huhtala, Maria Filomena Rocha Lima; Gomes, Ana Paula Martins; Ye, Qiang; Spencer, Paulette; De Paiva Gonçalves, Sérgio Eduardo


    The purpose of this study was to evaluate dentin permeability after dentin hypersensitivity treatments: fluoride, adhesive system, and collagen deproteinization with and without Nd:YAG laser exposure, and after erosive and abrasive challenges. Dentin permeability was assessed by measuring dentinal fluid flow using a permeability device. Eighty bovine dentin specimens (6 mm diameter/1 mm thickness) had permeability measured in the presence of the smear layer and after removal of the smear layer by ethylenediaminetetraacetic acid (EDTA). They were then divided into eight groups according to treatment (n = 10): Group C, control; Group L, Nd:YAG laser; Group F, fluoride; Group FL, fluoride plus Nd:YAG laser; Group A, adhesive; Group AL, adhesive plus Nd:YAG laser; Group D, 10% NaOCl plus adhesive; and group DL, NaOCl plus adhesive plus Nd:YAG laser. Nd:YAG laser was irradiated at 60 mJ/pulse/10 Hz/47.7 J/cm2/1 W and applied freehanded without contact for 60 sec. Permeability was measured 24 h after the treatments. The specimens were exposed to erosive and abrasive challenges for 5 days. Erosive challenge was done by immersion in Coca-Cola, four times a day/90 sec each. After the first and last erosive challenge of the day, the abrasive challenge was conducted by brushing the specimens (24,000 cycles/3.8 cm range/200 g weight), and permeability was measured again. Results were analyzed statistically using two factor ANOVA and Tukey tests (α = 0.05). With the exception of groups FL and A, all treatments reduced permeability. A significant reduction in permeability was seen when the treatments were combined with laser exposure. The association of adhesive and Nd:YAG laser led to the lowest rate of permeability after 24 h. NaOCl-induced deproteinization associated with Nd:YAG laser showed the lowest permeability rate after erosive/abrasive challenges. Dentin hypersensitivity treatments reduced dentin permeability when associated with Nd:YAG

  20. Iron plasma generation using a Nd:YAG laser pulse of several hundred picoseconds

    Tamura, Jun; Kumaki, Masafumi; Kondo, Kotaro; Kanesue, Takeshi; Okamura, Masahiro


    We investigated the high intensity plasma generated by using a Nd:YAG laser to apply a laser-produced plasma to the direct plasma injection scheme. The capability of the source to generate high charge state ions strongly depends on the power density of the laser irradiation. Therefore, we focused on using a higher power laser with several hundred picoseconds of pulse width. The iron target was irradiated with the pulsed laser, and the ion current of the laser-produced iron plasma was measured using a Faraday cup and the charge state distribution was investigated using an electrostatic ion analyzer. We found that higher charge state iron ions (up to Fe21+) were obtained using a laser pulse of several hundred picoseconds in comparison to those obtained using a laser pulse of several nanoseconds (up to Fe19+). We also found that when the laser irradiation area was relatively large, the laser power was absorbed mainly by the contamination on the target surface.

  1. A basic study of the interstitial laser prostatectomy using pulsed holmium: yttrium-aluminium-garnet (Ho:YAG) laser

    Daidoh, Yuichiro [National Defenese Medical Coll., Tokorozawa, Saitama (Japan)


    The efficacy of interstitial laser irradiation with a pulsed Ho:YAG laser ({lambda}: 2.1 {mu}m) was evaluated in the normal canine prostate. Pathological studies were performed up to 6 months after interstitial laser irradiation in 26 mongrel dogs. Two dogs without irradiation were as controls (control group). Prostate glands of the other 24 dogs were irradiated interstitially with a Ho:YAG laser. Four prostates were irradiated with 150-175 J/cm{sup 2} in fluence (low-fluence group) and 19 were irradiated with 500-600 J/cm{sup 2} in fluence (high-fluence group). Prostates glands were excised immediately, 1, 2, 3, or 6 months after irradiation and examined histologically. To investigate the influence of interstitial irradiation with a Ho:YAG laser on smooth muscle and/or on the adrenergic activity of the prostate, we also measured changes in intraluminal pressure of the prostatic urethra upon administration of epinephrine (10 {mu}g/kg) in 6 dogs before and after irradiation. In only the high-fluence group, smooth muscles and small vessels surrounded the ablated hole were destroyed, but the thickness of the thermal coagulation layer was only approximately 0.2 mm. These findings suggested that damage to the small vessels and smooth muscle may have been caused by laser-induced stress waves rather than by a thermal effect. In the high-fluence group, huge cavities were created in the laser-irradiated prostate gland 1 or 2 months after irradiation, prostatic volume was reduced, the cavities collapsed and prostatic volume was reduced by up to 50% at 6 months post-procedure. The prostatic urethra expanded following the reduction in volume. The maximal intraluminal change in pressure of the prostatic urethra decreased significantly after laser irradiation. Results indicate that interstitial irradiation of the prostate with a Ho:YAG laser with high-fluence may relieve the anatomical and functional obstruction of the prostatic urethra in benign prostatic hyperplasia. (H.O.).

  2. Pulsed dye laser versus long pulsed Nd:YAG laser in the treatment of angiokeratoma of Fordyce: A randomized, comparative, observer-blinded study.

    Ibrahim, S M


    Angiokeratoma of Fordyce is typically asymptomatic, blue-to-red papules with a scaly surface located on the scrotum, shaft of penis or labia majora. They can be treated with some locally destructive treatment modalities such as excision, electrocoagulation, cryotherapy and laser. To compare the effects of the pulsed dye laser versus long pulsed Nd:YAG laser in the treatment of angiokeratoma of Fordyce. Twenty tow patients with angiokeratoma of Fordyce were included in this study. All participants received three sessions of pulsed dye laser on the selected side or part of lesional area and long pulsed Nd:YAG laser on the other side or part of lesional area. Two dermatologists independently evaluated the photographs of the baseline and two-month follow-up after last session using a grade system in which treatment response was categorized into six grades. Both PDL and long pulsed Nd:YAG laser revealed statistically significant improvements in angiokeratoma of fordyce. Comparatively, there was a statistical difference between them (overall mean improvement with PDL, 61.8%, versus Nd:YAG, 77.63%; p laser are effective and safe in the treatment of angiokeratoma of Fordyce with better response in Nd:YAG laser than pulsed dye laser.

  3. Interaction of relativistic electrons with an intense laser pulse: High-order harmonic generation based on Thomson scattering

    Hack, Szabolcs [ELI-ALPS, ELI-HU Non-Profit Ltd., Dugonics tér 13, H-6720 Szeged (Hungary); Department of Theoretical Physics, University of Szeged, Tisza L. krt. 84-86, H-6720 Szeged (Hungary); Varró, Sándor [ELI-ALPS, ELI-HU Non-Profit Ltd., Dugonics tér 13, H-6720 Szeged (Hungary); Wigner Research Center for Physics, SZFI, PO Box 49, H-1525 Budapest (Hungary); Czirják, Attila [ELI-ALPS, ELI-HU Non-Profit Ltd., Dugonics tér 13, H-6720 Szeged (Hungary); Department of Theoretical Physics, University of Szeged, Tisza L. krt. 84-86, H-6720 Szeged (Hungary)


    We investigate nonlinear Thomson scattering as a source of high-order harmonic radiation with the potential to enable attosecond light pulse generation. We present a new analytic solution of the electron’s relativistic equations of motion in the case of a short laser pulse with a sine-squared envelope. Based on the single electron emission, we compute and analyze the radiated amplitude and phase spectrum for a realistic electron bunch, with special attention to the correct initial values. These results show that the radiation spectrum of an electron bunch in head-on collision with a sufficiently strong laser pulse of sine-squared envelope has a smooth frequency dependence to allow for the synthesis of attosecond light pulses.

  4. Experimental grounds for YAG:Er laser application to dentistry

    Bol'shakov, E. N.; Dolgikh, Robert A.; Zazulevskaya, Lidiya Y.; Zubov, Boris V.; Lobachyov, V. A.; Murina, T. M.; Prokhorov, Alexander M.


    Stornatologic service is most popular of all kinds of medical aid, since up to 90% of people suffer from caries, parodontosis holds the second place after such a widespread disease as cardiovascular pathology. The treatment of the tooth hard tissue, intervention into pulp and parodontium using conventional methods are accompanied with painfulness and unpleasant sensation. A lack of efficient methods of anesthesia and pulp devitalization, a high percentage of complica tions after pulpitis treatment made it necessary to search for new methods of treatment which exclude these negative aspects. Application of laser radiation may be one of the ways in resolving this problem. Such attempts have been made repeatedly with the development of laser technology.'3 However, not all of them turned out to be successful. The greatest difficulties occurred on surgical intervention into hard tooth tissue. The best results have been so far attained when using pulsed CO2 laser operated at the wavelength A =1O.61um. For instance, at pulse width 1O1us and frequency 10-20 Hz, the tooth channel drilling was efficient at energy density in pulse P . 10 JIcm2. 4'5 The electron-microscopic investigations have proved the tooth microstructure to be preserved for this laser operation mode. The traces of graphitization were observed only in the vicinity of the lateral walls of the channel.

  5. High Efficient LGp0 End Pumped Nd:YAG Laser

    Ngcobo, S


    Full Text Available The transformation of a single mode TEM00 Gaussian beam by forcing the laser to operate into a symmetrical single mode higher order TEMp0 Laguerre Gaussian beam intensity distribution is very useful in improving and substantially increasing...

  6. Pulsed Nd: YAG laser induces pulpal analgesia: a randomized clinical trial.

    Chan, A; Armati, P; Moorthy, A P


    This double-blind, randomized, clinical trial investigated the effectiveness and underlying mechanism of neural inhibition of pulsed Nd:YAG laser induction of pulpal analgesia compared with 5% EMLA anesthetic cream. Forty-four paired premolars from 44 orthodontic patients requiring bilateral premolar extraction from either dental arch were randomly assigned to the 'Laser plus Sham-EMLA' or 'EMLA plus Sham-Laser' treatment group. Analgesia was tested by an Electric Pulp Tester (EPT) and the cutting of a standardized cavity, which was terminated when participants reported sensitivity, and Visual Analogue Scale (VAS) and numbness were recorded. Statistical analyses were done by paired t test, McNemar's test, and a chi-squared test (p analgesia, by suppression of intradental nerve responses to electrical and mechanical stimuli. Such a laser provides an alternative for dental pain management (ANZ-Clinical Trial Registry: N12611001099910).

  7. Micro-Welding of Copper Plate by Frequency Doubled Diode Pumped Pulsed Nd:YAG Laser

    Nakashiba, Shin-Ichi; Okamoto, Yasuhiro; Sakagawa, Tomokazu; Takai, Sunao; Okada, Akira

    A pulsed laser of 532 nm wavelength with ms range pulse duration was newly developed by second harmonic generation of diode pumped pulsed Nd:YAG laser. High electro-optical conversion efficiency more than 13% could be achieved, and 1.5 kW peak power green laser pulse was put in optical fiber of 100 μm in diameter. In micro- welding of 1.0 mm thickness copper plate, a keyhole welding was successfully performed by 1.0 kW peak power at spot diameter less than 200 μm. The frequency doubled pulsed laser improved the processing efficiency of copper welding, and narrow and deep weld bead was stably obtained.

  8. Adaptable beam profiles from a dual-cavity Nd:YAG laser.

    Kim, D J; Mackenzie, J I; Kim, J W


    We report a technique to tailor a laser beam profile from a donut to quasi-top-hat intensity distribution, directly from the laser, simply achieved by simultaneous excitation and control of the relative contributions of the fundamental (TEM00) and first-order Laguerre-Gaussian (LG01) transverse modes. Exploiting a dual-cavity configuration with a single Nd:YAG gain element, adaptable continuous-wave laser beam profiles from the primary cavity could be obtained by varying the diffraction loss of an acousto-optic modulator in the secondary cavity. We investigate the resultant beam profiles as a function of pump power and the AOM diffraction loss, and discuss the prospects for tunable laser beams profiles.

  9. Critical power of keyhole formation in CW Nd:YAG laser deep penetration welding

    Qin Guoliang; Qi Xiukun; Lin Shangyang


    The energy model was founded to calculate the critical power of keyhole formation by using the limit principle in CW (continuous wave) Nd:YAG laser deep penetration welding process. The model was validated by experiments. The results show that there are two errors between the calculated critical power of keyhole formation and that of experiments: one is that the calculated results is less than those of experiments, which is caused by not considering the energy loss by heat conduction in the model of keyhole formation. The other is that there is 0.9 mm error between the axis of the calculated curve of critical power with location of laser focus and that of experimental curve, which is induced by the excursion of laser focus in laser deep penetration welding. At last, the two errors were revised according to the analyses of the errors.

  10. Transmission properties of all-silica fibres for high-power Nd:YAG lasers

    Reng, N.; Beck, T.


    The transmission properties of two different types of all-silica fibres, step index and graded-index fibres, are investigated using a multimode high-power cw Nd:YAG rod laser. The reflections from the fibre surface back into the laser cavity affect the laser power and the beam parameters, waist diameter and divergence. A set-up for simultaneously measuring these values in front of and behind a fibre is presented. The maximum laser power transmitted by fibres is dependent upon the beam parameters, the fibre design and the surface conditions. An upper limit for the maximum divergence which can be coupled into a fibre with a certain numerical aperture without loss is given. The beam parameters behind the fibre, related to the input parameters, are presented.

  11. Pilot in vivo animal study of bone regeneration by fractional Er: YAG-laser

    Altshuler, Gregory B.; Belikov, Andrey V.; Shatilova, Ksenia V.; Yaremenko, Andrey I.; Zernitskiy, Alexander Y.; Zernitckaia, Ekaterina A.


    The histological structure of the rabbit parietal bone during its regeneration after fractional Er: YAG-laser (λ=2.94μm) treatment was investigated by hematoxylin and eosin (H&E) stain. In 48 days after fractional laser treatment, bone samples contained micro-cavities and fragments of necrotic tissue with empty cellular lacuna and coagulated protein of bone matrix. In this case, necrotic lesions appeared around the periphery of micro-cavities created by laser radiation. Fragmentation of detrital mass and partial substitution of micro-cavities with fatty bone marrow were observed in bone samples in 100 days after fractional laser treatment, in contrast to the earlier period. Partial filling of micro-cavities edges by fibrous tissue with presence of osteoblasts on their inner surface was observed in 100 days also, that indicates regenerative processes in the bone.

  12. Hereditary haemorrhagic telangiectasia treated by pulsed neodymium:yttrium-aluminium-garnet (Nd:YAG) laser (1,064 nm).

    Werner, A; Bäumler, W; Zietz, S; Kühnel, T; Hohenleutner, U; Landthaler, M


    Hereditary haemorrhagic telangiectasia (HHT) is a familial, autosomal, dominant, multi-system, vascular, dysplasia. Besides repetitive epistaxis, cutaneous eruptive macules and nodules lead to recurring bleeding and cosmetic problems. We report on a pilot study of four cases of HHT in which cutaneous lesions were treated with a pulsed neodymium:yttrium-aluminum-garnet (Nd:YAG) laser (1,064 nm). Pulsed Nd:YAG laser treatment, without anaesthesia, was performed several times on eruptive angiomas on palmar and facial skin. Lesions on fingers and face mostly showed very good, or even complete, clearing after the first laser treatment. Several macules required multiple treatment; only a few lesions showed no effect. Pulsed Nd:YAG laser therapy (1,064 nm) appears to be an effective and safe treatment option for hereditary haemorrhagic telangiectasia on the skin of face and extremities.

  13. Evaluation of Er:YAG laser radiation cavity preparation under transmitted and polarized light and by electron microanalyser

    Dostalova, Tatjana; Krejsa, Otakar; Rokytova, Kveta; Jelinkova, Helena; Hamal, Karel


    The results of evaluation of Er:YAG radiation cavity preparation under transmitted and polarized light and by the electron microanalyzer are presented. We examined the longitudinal sections of intact teeth, teeth with early dental caries, teeth with laser preparation in enamel and teeth with Er:YAG laser preparation in enamel and dentine class I and V. We examined intact teeth and laser prepared teeth for the variation of mineralization. Phosphorus and calcium were regularly distributed. The margins of cavities had no necrosis zones. The defects of mineralization in caries depend on demineralization of hard tissues. In the structures was irregular loss of calcium and phosphorus. Thus, Er:YAG laser irradiation with water cooling has been found to be a non-invasive preparation technique.

  14. Computer modelling and numerical simulation of the solid state diode pumped Nd:YAG laser with intracavity saturable absorber

    Yashkir, Yuriy


    Stimulated emission in the Nd:YAG laser with a saturable absorber Cr:YAG is modelled as a superposition of interacting optical modes which are stable in a given optical cavity. The interaction of the active laser crystal and a passive Q-switch with diode pump and optical cavity modes is modelled with account of transversal two-dimentional variation of the pump field and of all participating optical modes. Each elementary volume of an active laser crystal and the Q-switching crystal in...

  15. Comparison of Q-switched Nd: YAG laser and fractional carbon dioxide laser for the treatment of solar lentigines in Asians.

    Vachiramon, Vasanop; Panmanee, Wikanda; Techapichetvanich, Thanya; Chanprapaph, Kumutnart


    Solar lentigines are benign pigmented lesions that occur mostly on sun-exposed areas. Q-switched and ablative lasers are effective for removing these lesions but the high incidence of postinflammatory hyperpigmentation raises concern in darker skin types. The objective of this study is to compare the efficacy and degree of postinflammatory hyperpigmentation with the Q-switched Nd:YAG and fractional carbon dioxide (CO2 ) laser for treatment of solar lentigines in Asians. Twenty-five Thai patients (skin phototype III-IV) with at least two lesions of solar lentigines on upper extremities were enrolled in this study. Two lesions were randomly selected for the treatment with a single session of Q-switched Nd:YAG or fractional CO2 laser. Outcomes were evaluated using physician grading scale, colorimeter, and patient self-assessment at 6 and 12 weeks after treatment. Side effects were recorded. A total of 532 nm Q-switched Nd:YAG laser showed significant improvement of pigmentation over fractional CO2 laser at 6th and 12th week by both colorimeter assessment and physician grading scale (P lasers was observed. In terms of patient self-assessment, 80% of the patients treated with 532 nm Q-switched Nd:YAG laser had excellent results compared to 8% in fractional CO2 laser group. However, fractional CO2 laser treatment had faster healing time and less pain score compared to Q-switched Nd:YAG laser. Q-switched Nd:YAG is superior to fractional CO2 laser for treatment of solar lentigines but requires longer healing time and produces more pain. The incidence of postinflammatory hyperpigmentation was not significantly different with both lasers. Further studies are needed to obtain the proper parameter and the treatment frequency of fractional CO2 laser in solar lentigines. © 2016 Wiley Periodicals, Inc.

  16. Microchannel fabrication on cyclic olefin polymer substrates via 1064 nm Nd:YAG laser ablation

    McCann, Ronán [Advanced Processing Technology Research Centre, Dublin City University, Glasnevin, Dublin 9 (Ireland); School of Mechanical and Manufacturing Engineering, Dublin City University, Dublin 9 (Ireland); Irish Separation Science Cluster, National Centre for Sensor Research, Dublin City University, Dublin 9 (Ireland); National Centre for Plasma Science and Technology, Dublin City University, Dublin 9 (Ireland); Bagga, Komal; Groarke, Robert [Advanced Processing Technology Research Centre, Dublin City University, Glasnevin, Dublin 9 (Ireland); School of Mechanical and Manufacturing Engineering, Dublin City University, Dublin 9 (Ireland); Irish Separation Science Cluster, National Centre for Sensor Research, Dublin City University, Dublin 9 (Ireland); Stalcup, Apryll [Irish Separation Science Cluster, National Centre for Sensor Research, Dublin City University, Dublin 9 (Ireland); School of Chemical Sciences, Dublin City University, Dublin 9 (Ireland); Vázquez, Mercedes, E-mail: [Advanced Processing Technology Research Centre, Dublin City University, Glasnevin, Dublin 9 (Ireland); Irish Separation Science Cluster, National Centre for Sensor Research, Dublin City University, Dublin 9 (Ireland); School of Chemical Sciences, Dublin City University, Dublin 9 (Ireland); Brabazon, Dermot [Advanced Processing Technology Research Centre, Dublin City University, Glasnevin, Dublin 9 (Ireland); School of Mechanical and Manufacturing Engineering, Dublin City University, Dublin 9 (Ireland); Irish Separation Science Cluster, National Centre for Sensor Research, Dublin City University, Dublin 9 (Ireland); National Centre for Plasma Science and Technology, Dublin City University, Dublin 9 (Ireland)


    Highlights: • Rapid single-step microchannel fabrication on optically transparent cyclic olefin polymer using IR Nd:YAG laser. • Ability to tailor channel depth between 12–47 μm demonstrated for single laser pass. • Use of multiple laser passes showed capability for finer depth control. • Potential applications in lab-on-chip and microfluidic devices. - Abstract: This paper presents a method for fabrication of microchannels on cyclic olefin polymer films that have application in the field of microfluidics and chemical sensing. Continuous microchannels were fabricated on 188-μm-thick cyclic olefin polymer substrates using a picosecond pulsed 1064 nm Nd:YAG laser. The effect of laser fluence on the microchannel morphology and dimensions was analysed via scanning electron microscopy and optical profilometry. Single laser passes were found to produce v-shaped microchannels with depths ranging from 12 μm to 47 μm and widths from 44 μm to 154 μm. The ablation rate during processing was lower than predicted theoretically. Multiple laser passes were applied to examine the ability for finer control over microchannel morphology with channel depths ranging from 22 μm to 77 μm and channel widths from 59 μm to 155 μm. For up to five repeat passes, acceptable reproducibility was found in the produced microchannel morphology. Infrared spectroscopy revealed oxidation and dehydrogenation of the polymer surface following laser ablation. These results were compared to other work conducted on cyclic olefin polymers.

  17. Experimental erbium: YAG laser photoablation of trabecular meshwork in rabbits: an in-vivo study.

    Dietlein, T S; Jacobi, P C; Schröder, R; Krieglstein, G K


    Photoablative laser trabecular surgery has been proposed as an outflow-enhancing treatment for open-angle glaucoma. The aim of the study was to investigate the time course of repair response following low-thermal Erbium: YAG laser trabecular ablation. In 20 anaesthetized rabbits gonioscopically controlled ab-interno photoablation of the ligamenta pectinata and underlying trabecular meshwork (TM) was performed with a single-pulsed (200 microseconds) Erbium: YAG (2.94 microns) laser. The right eye received 12-15 single laser pulses (2 mJ) delivered through an articulated zirconium fluoride fiberoptic and a 200 microns (core diameter) quartz fiber tip, the left unoperated eye served as control. At time intervals of 30 minutes, 2, 10, 30, and 60 days after laser treatment, eyes were processed for light- and scanning electron microscopy. The applied energy density of 6-4 J cm-2 resulted in visible dissection of the ligamenta pectinata and reproducible microperforations of the TM exposing scleral tissue accompanied by blood reflux from the aqueous plexus. The initial ablation zones measured 154 +/- 36 microns in depth and 45 +/- 6 microns in width. Collateral thermal damage zones were 22 +/- 8 microns. At two days post-operative, ablation craters were still blood- and fibrin-filled. The inner surface of the craters were covered with granulocytes. No cellular infiltration of the collateral thermal damage zone was observed. At 10 days post-operative, progressive fibroblastic proliferation was observed, resulting in dense scar tissue formation with anterior synechiae, proliferating capillaries and loss of intertrabecular spaces inside the range of former laser treatment at 60 days post-operative. Trabecular microperforations were closed 60 days after laser treatment in all rabbits. IOP in treated and contralateral eyes did not significantly change its level during whole period of observation. Low-thermal infrared laser energy with minimal thermal damage to collateral

  18. Orthogonally Linearly Polarized Dual Frequency Nd:YAG Lasers with Tunable Frequency Difference and Its Application in Precision Angle Measurement

    TAN Yi-Dong; ZHANG Shu-Lian


    The orthogonally linearly polarized dual frequency Nd:YAG lasers with two quarter wave plates in laser resonator are proposed. The intra-cavity variable birefringence, which is caused by relative rotation of these two wave plates in laser inner cavity, results in the frequency difference of the dual frequency laser also changeable. The theory model based on the Jones matrix is presented, as well as experimental results. The potential application of this phenomenon in precision roll-angle measurement is also discussed.

  19. Hypopigmentation Induced by Frequent Low-Fluence, Large-Spot-Size QS Nd:YAG Laser Treatments

    Wong, Yisheng; Lee, Siong See Joyce; Goh, Chee Leok


    The Q-switched 1064-nm neodymium-doped yttrium aluminum garnet (QS 1064-nm Nd:YAG) laser is increasingly used for nonablative skin rejuvenation or "laser toning" for melasma. Multiple and frequent low-fluence, large-spot-size treatments are used to achieve laser toning, and these treatments are associated with the development of macular hypopigmentation as a complication. We present a case series of three patients who developed guttate hypomelanotic macules on the face after receiving laser t...

  20. Nd:YAG Laser to obtain Irregularities on the Inner Surface of Porcelain.

    Porto, Thiago Soares; Porto, Betina Grehs; de Campos, Edson Alves; Porto-Neto, Sizenando de Toledo; da Silva, Monica Barros; Bhandi, Shilpa H; Tonetto, Mateus Rodrigues; Dinelli, Welingtom; Bandeca, Matheus Coelho


    The aim of this study was to evaluate the inner surface of two ceramic systems: IPS Empress II (Ivoclar Vivadent, Germany) and In-Ceram Alumina (Vita Zahnfabrick, Germany) submitted to surface treatments, especially by Nd:YAG laser. Fifty samples were prepared in pellet form for each ceramic system according to manufacturers' specifications. The samples were stored at room temperature and then be subjected to surface treatment: without treatment (T0) (control), hydrofluoric acid-etched (T1), hydrofluoric acid-etched associated with the airborne particle-abraded (T2); CoJet system (T3), Nd:YAG laser (T4). The data were performed the statistical analysis by ANOVA and Tukey's test (p treatment with hydrofluoric acid (T1), associated with hydrofluoric acid and airborne particle-abraded (T2) and Nd:YAG laser (T4), had no statistically significant difference, whereas for the IPS Empress System II treatment with hydrofluoric acid (T1) and hydrofluoric acid associated with airborne particle-abraded (T2), had no statistically significant difference between the system and also CoJet (T3) and hydrofluoric acid associated with the airborne particle-abraded (T2). Photomicrographs of scanning electron microscopy showed different characteristics to the treatments for each ceramic system. The IPS Empress II had the appearance of favoring the retention when treated with hydrofluoric acid, as well as its association with the airborne particle-abraded. Uncertainty in Alumina, treatment with hydrofluoric acid associated with the airborne particle-abraded and CoJet system and provided a surface with irregularities. With respect to the laser further studies should be performed for parameters that are ideal for your application. The ceramic restorations are attractive due of their excellent esthetics and the ability to stay for long periods. However, the retention of ceramic requires further study.

  1. Effects of Er:YAG laser treatments on surface roughness of base metal alloys.

    Kunt, Göknil Ergün; Güler, Ahmet Umut; Ceylan, Gözlem; Duran, Ibrahim; Ozkan, Pelin; Kirtiloğlu, Tuğrul


    We investigated the effects of different Er:YAG laser treatments on the surface roughness of base metal alloys. A total of 36 specimens were prepared of two base metal alloys (Wiron 99, Bellabond plus). The surfaces of the specimens were standardized by gradual wet grinding with 320-, 600-, 800- and 1,000-grit silicon carbide paper for 10 s each on a grinding machine at 300 rpm. Specimens of each alloy were randomly divided into six groups (n = 6) comprising a control group (group C), a group sandblasted with Al(2)O(3) powder at 60 psi for 10 s through a nozzle at a distance of 10 mm (group S), and four Er:YAG laser (Fotona AT) treatment groups. The laser treatment groups were as follows: 500 mJ, 10 Hz, 100 μs (group 500MSP); 500 mJ, 10 Hz, 300 μs (group 500SP); 400 mJ, 10 Hz, 100 μs (group 400MSP); and 400 mJ, 10 Hz, 300 μs (group 400SP). Surface roughness measurements (Ra) were performed using a profilometer. The data were analysed by two-way ANOVA, and mean values were compared using Tukey's HSD test (α = 0.05). According to the two-way ANOVA results, the base metal alloys and interaction between base metal alloy and surface treatment were not statistically significant different (p > 0.05), the surface treatments were significantly different (p Er:YAG laser treatment at 400 and 500 mJ/10 Hz is not an alternative method for surface roughening of base metal alloys.

  2. Treatment of Axillary Osmidrosis Using a Subcutaneous Pulsed Nd-YAG Laser

    Daejin Kim


    Full Text Available Background Axillary osmidrosis is characterized by an unpleasant odor, profuse sweating, andin some instances, staining of clothes that may socially and psychologically impair affectedindividuals. Various types of surgical procedures have been developed for the treatment ofaxillary osmidrosis. This study was undertaken to evaluate the effectiveness of subcutaneouspulsed neodymium: yttrium-aluminum-garnet (Nd-YAG laser treatment for the treatment ofaxillary osmidrosis.Methods Twenty-nine patients with axillary osmidrosis were included in this study. Patientswere categorized according to the results of an axillary malodor grading system, and asubcutaneous pulsed Nd-YAG laser was applied to all patients. The treatment area for theappropriate distribution of laser energy was determined using the iodine starch test (Minor’stest against a grid pattern composed of 2×2 cm squares. The endpoint of exposure was300 to 500 J for each grid, depending on the preoperative evaluation results. The resultswere evaluated by measurement of axillary malodor both pre- and postoperatively using thegrading system and iodine starch test.Results The average follow-up period was 12.8 months. Nineteen patients had a fair-togoodresult and ten patients had poor results. The postoperative Minor’s test demonstratedthat there were remarkable improvements for patients with mild to moderate symptoms.Complications including superficial second degree burns (n=3 were treated in a conservativemanner. A deep second degree burn (n=1 was treated by a surgical procedure.Conclusions Subcutaneous pulsed Nd-YAG laser has many advantages and is an effectivenoninvasive treatment for mild to moderate axillary osmidrosis.

  3. Experimental removal of subgingival calculus with the Er:YAG laser

    Keller, Ulrich; Hibst, Raimund


    The purpose of this study was to evaluate the effects of the Er:YAG laser removal of subgingival calculi in periodontal treatment and to describe laser-induced cementum surface alterations. Freshly extracted human teeth with adherent plaques and mineralized calculi were laser treated using modified quartz fiber tips in direct contact to the root surface. For the fiber tip tested, the ablation threshold was 6.5 mJ. An effective removal of calculi was possible with 50 mJ resp. 150 mJ for a triple fiber. For the latter, a mass loss with a mean of about 5.1. mg/min was achieved. Histologic examinations of the cementum surface showed smoothed appearance alternately with rough depressions of the fiber tips, which can be discussed as a good precondition for periodontal tissue regeneration. Maximum temperature increase of 1.4 K was reached in the pulp, if an additional water irrigation was applied to the root surface. From these results it can be concluded that with the Er:YAG laser an effective removal of subgingival calculi can be performed without thermal risk for the pulp.

  4. [Thermographic assessment of thermal effects of Er:YAG laser in periodontal surgery].

    Zmuda, Stanisław; Ignatowicz, Elzbieta; Stankiewicz, Justyna; Marczyńiska-Stolarek, Magdalena; Dabrowski, Mirosław


    An assessment of thermal effect of Er:YAG laser (KEYII, KaVo) on oral soft tissues in select procedures. Experimental researches were carried out on Wistar rats. To measure the temperature changes the thermal imaging camera (ThermaCAM SC3000, FLIR Systems) was used. There has been a significant increase of temperature observed on the end of optical fibre: the mean temperature ranged from 270 to 360 degrees C (at laser energy of 100 mJ and repetition rate of 25 Hz) and from 230 to 290 degrees C (300 mJ, 15 Hz). On the surface of oral mucosa thermal changes at the time of laser frenulectomy was analysed along the line of incision. The temperature above 50 degrees C was recorded on the length of 2 mm (at 100 mJ) and 3 mm (at 300 mJ). The temperature maintained on this level for about 0.4 s. On the surface of tongue during lingual mucosa excision the temperature above 40 degrees C was observed on the length of 1.6 mm (80 mJ, 2 Hz) or 2.5 mm (160 mJ, 2 Hz). The rate of cooling for both cases was lower than 0.5 s. To prevent undesirable thermal side effects from an Er:YAG laser optical fibre should be moved very fluently in non-contact mode.

  5. Optimizing the Yb:YAG thin disc laser design parameters

    Javadi-Dashcasan, M.; Hajiesmaeilbaigi, F.; Razzaghi, H.; Mahdizadeh, M.; Moghadam, M.


    Based on quasi-three-level system, a numerical model of continuous wave thin disc laser is proposed. The fluorescence concentration quenching (FCQ), refractive index depending concentration effects and temperature distribution in the gain medium have been taken into account in the model. The first and second phenomena are not included in previously models. The model is used to determine optimum design parameters and to calculate the influence of various parameters like temperature, number of pump beam passes, active ions concentration and the crystal thickness on the operational efficiency of the laser. This model shows that for higher doping concentrations (>15%) the optical efficiency is decreased due to fluorescence concentration quenching. Our results are excellently in agreement with experimental results.

  6. Diode end-pumped 1123-nm Nd:YAG laser with 2.6-W output power

    Zhiqiang Cai; Meng Chen; Zhigang Zhang; Rui Zhou; Wuqi Wen; Xin Ding; Jianquan Yao


    We present a compact and high output power diode end-pumped Nd:YAG laser which operates at the wavelength of 1123 nm. Continuous wave (CW) laser output of 2.6 W was achieved at the incident pump power of 15.9 W, indicating an overall optical-optical conversion efficiency of 16.4%, and the slope efficiency was 18%.

  7. Comparison of Q-switched Nd:YAG laser alone versus its combination with ultrapulse CO2 laser for the treatment of black tattoo.

    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 CO2 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 CO2 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 effect profile of both the groups. For refractory professional tattoos, combination of ultrapulse CO2 laser and QS Nd:YAG laser is superior to QS Nd:YAG laser alone.

  8. Waveguide and articulated arm for Er:YAG laser system: shape and depth of laser cavity in hard dental tissues

    Jelinkova, Helena; Dostalova, Tatjana; Miyagi, Mitsunobu; Wang, You; Shi, Yi-Wei; Dolezalova, Libuse; Hamal, Karel; Krejsa, Otakar; Kubelka, Jiri; Prochazka, Stanislav


    The aim of our study was to verify the efficiency of delivery systems for Er:YAG laser radiation which could be used in dentistry. The influence of increasing energy and number of pulses on a profile and depth of drilled holes was investigated. Er:YAG laser was operating in a free-running mode, generating a length of pulses 200 microsecond with a maximum energy of 500 mJ. The delivery systems investigated were an articulated arm and a fluorocarbon polymer-coated silver hollow glass waveguide. The prepared hard tissues were a sliced part of enamel, dentine and ivory. The laser radiation was directed on them by focusing optics (CaF2 lens) together with the cooling water to ensure that the tissues will not be burned. For the evaluation of shapes, depth and profiles of the prepared cavities the metallographic microscope, x-ray microtomograph and scanning electron microscope were used. From the results it was observed that the profile and depth of the cavities prepared by the laser radiation delivered by the various systems (waveguide or articulated arm) are not the same. The laser radiation delivered by waveguide produces a larger diameter cavity with a lower depth. The holes are smoother and without side effects.

  9. Evaluation of pneumatic versus holmium:YAG laser lithotripsy for impacted ureteral stones.

    Binbay, Murat; Tepeler, Abdulkadir; Singh, Avinash; Akman, Tolga; Tekinaslan, Erdem; Sarilar, Omer; Baykal, Murat; Muslumanoglu, Ahmet Yaser


    We prospectively analyzed and compared the effectiveness and complications of pneumatic lithotripter with a holmium:yttrium-aluminum-garnet (Ho:YAG) laser for the ureterorenoscopic management of impacted ureteral stones. From January 2006 to January 2008, we performed retrograde endoscopic treatment in 288 patients with ureteral stones in our clinic. The patients with impacted stones were randomized into two groups according to the lithotripter used to fragment the stone: pneumatic (n = 40) and laser (n = 40). The preoperative, operative, and post-operative follow-up findings were analyzed and compared. The average stone size was similar in both groups (118.8 ± 58.3 mm(2) vs. 110.7 ± 54.4 mm(2)). The calculi were located in the distal ureter in most of the patients in both groups (65% in pneumatic group and 52.5% in laser group). The operation time was significantly diminished in the laser group (P = 0.001). The stone-free rates after a single ureteroscopic procedure were 80 and 97.5% in the pneumatic and laser groups, respectively (P = 0.03). Auxiliary treatments were needed in seven patients in the pneumatic group, while only one patient in the laser group (P = 0.05) needed this treatment. After the additional procedures, a 100% success rate was achieved in both groups. The rate of double J stent insertion was significantly higher in the pneumatic group (P = 0.01). In the pneumatic group, four cases of stone up-migration and one case of post-operative stricture were seen, whereas only one case of stone up-migration was noted in the laser group. Our comparative study has shown that the use of Ho:YAG as an intracorporeal lithotripter during ureteroscopic management of impacted ureteral stones is highly efficient with high success rates, regardless of the stone location.

  10. SEM evaluation of the hybrid layer after cavity preparation with Er:YAG laser.

    de Barceleiro, Marcos Oliveira; Dias, Kátia Regina Hostílio Cervantes; Sales, Helena Xavier; Silva, Bárbara Carvalho; Barceleiro, Cristiane Gomes


    This study compared the thickness of the hybrid layer formed using Scotchbond Multi-Purpose Plus, Single Bond 2, Prime & Bond 2.1 and Xeno III on a dentin surface prepared with a diamond bur in a high speed handpiece or prepared with an Er:YAG laser used with two parameters of pulse energy (200 and 400 mJ) and two parameters of frequency (4 and 6 Hz). Flat dentin surfaces obtained from 20 human third molars were treated with the two methods and were then prepared with the dentin adhesive systems according to the manufacturers' instructions. After a layer of composite was applied, the specimens were sectioned, flattened, polished and prepared for Scanning Electronic Microscopy observation. Five different measurements of the hybrid layer thickness were obtained along the bonded surface in each specimen. The results were statistically analyzed using Analysis of Variance and Student-Newman-Keuls tests (p cavity preparation method, four groups were formed: Group I (diamond bur) > Group II (Laser 200 mJ/4 Hz) = Group III (Laser 200 mJ/6 Hz) > Group IV (Laser 400 mJ/4 Hz) > Group V (Laser 400 mJ/6 Hz). When comparing the dentin adhesive systems, there were no statistically significant differences. These results showed that the four tested dentin adhesive systems produced a 2.90 +/- 1.71 microm hybrid layer in dentin prepared with a diamond bur. This hybrid layer was regular and routinely found. In the laser groups, the dentin adhesive systems produced hybrid layers ranging from 0.41 +/- 1.00 microm to 2.06 +/- 2.49 microm, which were very irregular and not routinely found. It was also concluded that the Er:YAG laser, with the parameters used in this experiment, has a negative influence on the formation of a hybrid layer and cavity preparation methods influence formation of the hybrid layer.

  11. Problems of YAG nanopowders compaction for laser ceramics

    Bagayev, S. N.; Kaminskii, A. A.; Kopylov, Yu. L.; Kravchenko, V. B.


    Slip casting and colloidal slip casting at high pressure of yttrium aluminum garnet powders were investigated. It was found that the presence of residual pores in laser oxide ceramics was determined mainly by big size pores in the compact. The size of pore in compact is critical when it is greater than the mean size of initial particles. It was shown that formation of pores' structure in compact was controlled by appearance of quasi-particles in heavy loaded slurry. Pores concentration is critical for ceramics optical transmittance.

  12. Evaluation of surface topography of zirconia ceramic after Er:YAG laser etching.

    Turp, Volkan; Akgungor, Gokhan; Sen, Deniz; Tuncelli, Betul


    The aim of this study is to evaluate the effect of Erbium: yttrium-aluminum-garnet (Er:YAG) laser with different pulse lengths on the surface roughness of zirconia ceramic and airborne particle abrasion. Er:YAG laser treatment is expected to be an alternative surface treatment method for zirconia ceramics; however, the parameters and success of the application are not clear. One hundred and forty zirconia discs (diameter, 10 mm; thickness, 1.2 mm) were prepared by a computer-aided design and computer-aided manufacturing (CAD/CAM) system according to the manufacturer's instructions. Specimens were divided into 14 groups (n=10). One group was left as polished control, one group was air-particle abraded with Al2O3 particles. For the laser treatment groups, laser irradiation was applied at three different pulse energy levels (100, 200, and 300 mJ) and for each energy level at four different pulse lengths; 50, 100, 300, and 600 μs. Surface roughness was evaluated with an optical profilometer and specimens were evaluated with scanning electron microscopy (SEM). Data was analyzed with one way ANOVA and Tukey multiple comparison tests (α=0.05). For the 100 and 200 mJ laser etching groups, 50 and 100 μs laser duration resulted in significantly higher surface roughness compared with air-particle abrasion (p0.05). For the 300 mJ laser etching groups; there was no statistically significant difference among the Ra values of 50 μs, 100 μs, 300 μs, 600 μs, and air-particle abrasion groups (p>0.05). In order to increase surface roughness and promote better bonding to resin luting agents, Er:YAG laser etching may be an alternative to air-particle abrasion for zirconia ceramics. However, high levels of pulse energy and longer pulse length may have an adverse effect on micromechanical locking properties, because of a decrease in surface roughness.

  13. Pathomorphological distinction between Er:YAG and diode lasers on the excisional biopsy of the oral mucosa

    Georgi T. Tomov


    Full Text Available Background – In oral pathology, laser devices can provide important advantages, especially in the treatment of certain lesions. However, there is controversy about the use of some wavelengths in the analysis of suspected dysplastic or neoplastic lesions, raising doubt about the laser's suitability for use in biopsy procedures. The present pilot study evaluates the pathomorphological characteristics and suitability of Er:YAG and diode lasers for performing excisional biopsies in the oral mucosa with special emphasis on the extent of the thermal damage zone created. Material and Methods – 10 patients were randomly assigned to one diode or one Er:YAG laser groups. The Er:YAG laser(2940nm was used in a pulsed wave mode 200mJ/35Hz with a power of 7 W. Power settings for the diode laser(810 nm were 3 W in a pulsed mode. The thermal damage zone of the two lasers and intraoperative and postoperative complications were assessed and compared.All biopsy specimens were evaluated by optical microscopy by threeblinded pathologists. After establishing the pathomorphological diagnosis of the lesion assessed, the pathologists measured the maximal width of the peripheral thermal damage zone in the specimen in μm and classified it using appropriate index. Results – The peripheral thermal damage zone on the borders of the excisional biopsies was significantly smaller with the Er:YAG laser compared to the diode laser regarding values in μm or pathomorphological index scores. No postoperative complications occurred in any of the two groups. Conclusions – The Er:YAG laser seems to be appropriate for excisional biopsies of benign oral mucosal lesions. The Er:YAG laser offers clear advantages in terms of smaller thermal damage zones over the diode laser. Although in some samples thermal damage was minimally visible, in all samples histological evaluation was clearly possible. The study demonstrated that the Er:YAG laser can be safely used in oral biopsy

  14. Longitudinal Evaluation of Bond Strength to Enamel of Dental Adhesive Systems Associated with Nd:YAG Laser.

    Barcellos, D C; Batista, G R; Pucci, C R; Persici, E S; Borges, A B; Torres, C R G; Fonseca, B M; Gonçalves, S E P


    This study evaluated the durability of bond strength to enamel using total-etch (Single Bond/SB) and self-etch (Clearfil SE Bond/CSEB) adhesives associated with neodymium:yttrium-aluminu-garnet (Nd:YAG) laser irradiation through the uncured adhesives. Bovine incisors were worn to expose an area of enamel and were divided into four groups: group 1 (control) SB + polymerization; group 2 (control) CSEB + polymerization; group 3 (laser) - SB + Nd:YAG laser (174.16 J/cm(2)) + polymerization; and group 4 (laser) CSEB + Nd:YAG (174.16 J/cm(2)) + polymerization. Blocks of composite were fabricated and stored for 24 hours or 12 months, sectioned into beams, and submitted to microtensile tests. Results were analyzed by three-way analysis of variance (ANOVA) (adhesive, technique, and storage time) and Tukey tests. ANOVA revealed significant differences for adhesive × technique and technique × storage time (padhesive × technique (standard deviation) were as follows: SB/control = 35.78 (6.04)a; SB/laser = 26.40 (7.25)b, CSEB/control = 26.32 (5.71)b, CSEB/laser = 23.90 (7.49)b. For interaction technique × storage time the mean values were as follows: control/24 hours = 32.58 (6.49)a; control/12 months = 29.52 (8.38)a; laser/24 hours = 29.37 (5.71)a; laser/12 months = 20.92 (6.5)b. Groups with the same letters showed no statistically significant differences. Scanning electron microscope analysis showed evident areas of micromorphological alterations in lased samples after 12 months of water storage. Nd:YAG laser irradiation of enamel through unpolymerized total-etch adhesive significantly reduced bond strength compared with the control. Bond strength decreased when enamel samples irradiated with Nd:YAG laser through unpolymerized adhesives were stored in water for 12 months.

  15. Do Parameters Of Irradiation Influences The Apical Sealing Of Er:YAG Laser Apicetomies?

    Marques, Aparecida Maria Cordeiro; dos Santos, Jean Nunes; Pinheiro, Antonio Luiz Barbosa


    Failures on the sealing of the tooth apex are responsible for many failures of apical surgeries. The Er:YAG laser has been proposed as an alternative for the use of rotator instruments on surgical endodontics. 12 human extracted canines had root endodontic treatment being the apical limit was set at 1mm before the apical foramen and were distributed into 2 groups. On group I, apicectomy was performed with the Er:YAG laser (250 mJ/15 Hz). Apical cut was performed of perpendicular mode with 3mm from the apical foramen. On Group II, the same procedures and the same sequence as above was used, varying only the parameters of the Er:YAG laser (400 mJ/6 Hz). The specimens were divided into groups and fixed, by the cervical third, on wax. Impermeabilization of the residual root apical third was performed following the same procedures used in the cervical third but the residual apex was left free from the impermeabilization. After that, the roots were immersed in a 2% methylene blue solution and placed in a bacteriological oven for 48 h. The segments were visually observed and the one showing greatest level of dye leakage was selected and kept in individual container and coded accordingly. Apical staining was measured using a stereoscopic magnifying glass; a compass; and caliper. The results showed that Group I showed significantly different higher mean level of dye leakage (5.67±4.9, papicectomies carried out with 400 mJ/6 Hz showed the smallest infiltration value.

  16. Odontoblast response to cavity preparation with Er:YAG laser in rat molars: an immunohistochemical study.

    Shigetani, Yoshimi; Suzuki, Hironobu; Ohshima, Hayato; Yoshiba, Kunihiko; Yoshiba, Nagako; Okiji, Takashi


    This study aimed to examine the dynamics of odontoblast-lineage cells following cavity preparation with erbium:yttrium-aluminum-garnet (Er:YAG) laser in rat molars. Cavity preparation was made with Er:YAG laser in the mesial surface of the maxillary left first molar of 8-week-old Wistar rats. Contralateral first molar served as unirradiated control. Immediately, 6 and 12 h and 1, 2, 3, 5 and 7 days after the lasing (n = 5, each), specimens were collected and processed for immunohistochemistry for heat-shock protein (HSP)-25 and nestin as markers for odontoblast-lineage cells. Cell proliferation assay using bromodeoxyuridine (BrdU) labeling was also performed. Unirradiated teeth showed HSP-25- and nestin-immunoreactivity in odontoblasts. At 6-12 h after irradiation, the odontoblastic layer was disorganized and some of odontoblasts lost the immunoreactivity to HSP-25 and nestin. At 1-2 days, however, HSP-25- and nestin-immunoreactivities in the odontoblast layer showed a noticeable recovery, resulting in the rearrangement of odontoblast-like cells intensely immunoreactive to HSP-25 and nestin at 3-7 days. BrdU-positive cells showed a significant increase at 2 days (P cavity preparation with Er:YAG laser induced mild and reversible damage to odontoblasts. The reparative process was characterized by the rearrangement of HSP-25- and nestin-immunoreactive odontoblast-like cells, which took place subsequent to the odontoblastic layer disorganization with partial loss of these immunoreactivities.

  17. Modeling of end-pumped Yb:YAG thin-disk lasers with nonuniform temperature distribution.

    Zhu, Guangzhi; Zhu, Xiao; Zhu, Changhong; Shang, Jianli; Wan, Hailin; Guo, Fei; Qi, Lijun


    A plane wave model with nonuniform temperature distribution in the thin-disk crystal is developed to describe the dynamic behavior of an end-pumped Yb:YAG thin-disk laser. A set of couple-rate equations and 2D stationary heat-conduction equations are derived. The stable temperature distribution in the disk crystal is calculated using a numerical iterative method. The analytic expression is capable of dealing with more practical laser systems than previous works on this subject as it allows for nonuniform temperature distribution in the disk crystal. Based on these results, we examined laser output intensity as a function of pump intensity, dopant concentration, resonator coupler reflectivity, crystal thickness and temperature of cooling liquid.

  18. Intensity Tuning in Single Mode Microchip Nd:YAG Laser with External Cavity

    TAN Yi-Dong; ZHANG Shu-Lian


    We investigate the characteristics of intensity tuning in a single mode microchip Nd:YAG laser with an external cavity. The undulation of laser intensity in a period of λ/2 change of the internal cavity length is observed.Two different optical feedback cases are performed. One is an external cavity reflector perfectly aligned and the other is an external cavity reflector tilted. However, the fluctuation frequency of laser intensity in a period of λ/2 change of the internal cavity length in these two cases is found to be determined by the ratio of external cavity length to internal cavity length. Meanwhile, for the tilted external cavity, the fluctuation frequency is also related to multiple feedbacks in the tilted external cavity.

  19. Fragmentation process during Ho:YAG laser lithotripsy revealed by time-resolved imaging

    Beghuin, Didier; Delacretaz, Guy P.; Schmidlin, Franz R.; Rink, Klaus


    The stone fragmentation process induced during Ho:YAG laser lithotripsy was observed by time-resolved flash video imaging. Possible acoustic transient occurrence was simultaneously monitored with a PVDF needle hydrophone. We used artificial and cystine kidney stones. We observed that, although the fragmentation process is accompanied with the formation of a cavitation bubble, cavitation has a minimal incidence on stone fragmentation. Fragment ejection is mainly due to a direct laser stone heating and vaporization of stone organic constituents and interstitial water. The minimal effect of the cavitation bubble for fragmentation is confirmed by acoustic transients measurements, which reveal weak pressure transients. This is in contrast with the fragmentation mechanisms induced by laser of shorter pulse duration.

  20. Effectiveness of Er:YAG laser in cavity preparation for retrograde filling--in vitro study.

    Karlović, Zoran; Grgurević, Lovro; Verzak, Zeljko; Modrić, Vesna-Erika; Sorić, Pjetra; Grgurević, Josko


    The purpose of this study was to determine the sealing quality of Super EBA cement in laser prepared root-end cavities in comparison with root-end cavities classically prepared with steel burrs. Two groups of three millimeter root sections were prepared. The first group was prepared with the Er:YAG laser and the second group with a steel burr mounted on a surgical handpiece. The sections were filled with Super EBA cement and tested for leakage with fluid transport techniques. The sealing quality of Super EBA cement in the classically prepared root-end cavities was better, but there was no statistically significant difference between the two preparation techniques. The possible reason for greater leakage in the laser prepared root-end cavities was probably the irregular shape of the root-end cavity.

  1. Low loss depressed cladding waveguide inscribed in YAG:Nd single crystal by femtosecond laser pulses.

    Okhrimchuk, Andrey; Mezentsev, Vladimir; Shestakov, Alexander; Bennion, Ian


    A depressed cladding waveguide with record low loss of 0.12 dB/cm is inscribed in YAG:Nd(0.3at.%) crystal by femtosecond laser pulses with an elliptical beam waist. The waveguide is formed by a set of parallel tracks which constitute the depressed cladding. It is a key element for compact and efficient CW waveguide laser operating at 1064 nm and pumped by a multimode laser diode. Special attention is paid to mechanical stress resulting from the inscription process. Numerical calculation of mode distribution and propagation loss with the elasto-optical effect taken into account leads to the conclusion that the depressed cladding is a dominating factor in waveguide mode formation, while the mechanical stress only slightly distorts waveguide modes.

  2. High-power Er:YAG laser with quasi-top-hat output beam.

    Kim, J W; Mackenzie, J I; Hayes, J R; Clarkson, W A


    A simple method for simultaneously exciting the fundamental (TEM00) transverse mode and first order Laguerre-Gaussian (LG01) donut mode in an end-pumped solid-state laser to yield a quasi-top-hat output beam is reported. This approach has been applied to an Er:YAG laser, in-band pumped by an Er,Yb fiber laser, yielding 9.6 W of continuous-wave output at 1645 nm in a top-hat-like beam with beam propagation factor (M2)<2.1 for 24 W of incident pump power at 1532 nm. The corresponding slope efficiency with respect to incident pump power was 49%. The prospects of further scaling of output power and improved overall efficiency are considered.

  3. Nd:YAG Laser Cleaning of Red Stone Materials: Evaluation of the Damage

    Colombo, C.; Martoni, E.; Realini, M.; Sansonetti, A.; Valentini, G.

    Lasers have been tested, during the recent past, as a useful cleaning method in conservation treatments: this is due to selectivity and precision of its performance. Nevertheless some colour changes have been detected using Nd:YAG laser sources, especially on white and red coloured substrates. Colour changes on white marble and other white architectural materials have already been widely surveyed. This chapter focuses on the interaction of laser radiation with two kinds of red materials: red Verona limestone and terracotta. These materials have been chosen because of their large use in northern Italian architecture and in statuary. Red Verona limestone is not homogenous in hue, owing to the presence of calcareous nodules (lighter in colour) and clay veins (dark reddish colour).

  4. Operation of the nose using Nd-YAG and holmium laser

    Kukwa, Andrzej; Tulibacki, Marek P.; Zajac, Andrzej; Dudziec, Katarzyna


    During more than 5 years Nd:YAG and Holmium laser has been used in our ENT Department for the treatment of varies pathological changes. Most of our cases were previously treated many times because of recurrences of the nasal polyps. As a rule the treatment was given in one to three sessions. Each patient was very closely monitored. The time period between the session was 2-4 weeks. The consequent application of laser was dependent on healing process. All adults' patients were treated in local anesthesia using 1,5 percent of Cocaine and 10 percent Xylocaine applied in a spray; no other anesthetics were needed, although in some patients 10 mg Valium was administered before first session of laser application. We do not observe a severe bleeding needed sponge or a nose package. Among advantages we have to concentrate on two: the recurrences of nasal polyps are definitely much rare and patient may appear at work at the same day.

  5. Experimental investigation on CFRP milling by low power Q-switched Yb:YAG laser source

    Genna, S.; Tagliaferri, F.; Papa, I.; Leone, C.; Palumbo, B.


    In the present study, laser milling of CFRP plate by means of a 30W Q-Switched Yb:YAG fiber laser is investigated through statistical analysis. Milling tests were performed at the nominal power changing the pulse power; the scanning speed, the hatch distance and the released energy. Design of Experiments (DoE) and ANalysis Of VAriance (ANOVA) were applied with the aim to improve the process performances in term of material removal rate and heat affected zone extension. The results show that, the adopted laser is an effective solution for the CFRP milling. Moreover, adopting an accurate approach to the problem, process variability and material damages can be easily reduced.

  6. A high-power spatial filter for Thomson scattering stray light reduction

    Levesque, J. P.; Litzner, K. D.; Mauel, M. E.; Maurer, D. A.; Navratil, G. A.; Pedersen, T. S.


    The Thomson scattering diagnostic on the High Beta Tokamak-Extended Pulse (HBT-EP) is routinely used to measure electron temperature and density during plasma discharges. Avalanche photodiodes in a five-channel interference filter polychromator measure scattered light from a 6 ns, 800 mJ, 1064 nm Nd:YAG laser pulse. A low cost, high-power spatial filter was designed, tested, and added to the laser beamline in order to reduce stray laser light to levels which are acceptable for accurate Rayleigh calibration. A detailed analysis of the spatial filter design and performance is given. The spatial filter can be easily implemented in an existing Thomson scattering system without the need to disturb the vacuum chamber or significantly change the beamline. Although apertures in the spatial filter suffer substantial damage from the focused beam, with proper design they can last long enough to permit absolute calibration.

  7. Morphological change study on root surfaces treated with curettes, sonic instruments or Er:YAG laser; Estudo in vitro da alteracao morfologica em superficie radicular tratada com curetas, aparelho ultrasonico ou com laser de Er:YAG

    Guimaraes Filho, Arlindo Lopes


    Periodontal disease is caused by dental plaque and dental calculus on roots surfaces, specially on cervical areas. As dental plaque is the main cause and dental calculus a secondary one, it is practically impossible to separate one factor to the other one. In order to get periodontal tissue health it is necessary to eliminate dental plaque and calculus from root surfaces. In this sense, Er:YAG laser comes in as an excellent way to control periodontal disease, not only, by removing calculus and dental plaque but also for its bacteria reduction. The aim of this study is to compare, by S.E.M., root surfaces changing when they are treated with curettes and ultrasonic scaling or Er:YAG laser irradiation with two different energy levels of 60 mJ/pulse and 100 mJ/pulse and repetition tax of 10 Hz (in the display). It is also objective of this study to check a possible thermic damage to pulp tissue when the roots surfaces are irradiated with Er:YAG laser. We used for this study, five human dental roots, each one of them were cut into four samples, giving us a total of twenty samples, which were divided in five groups of four samples each one. The control group, we did not indicated any kind of treatment. The first group, the roots samples were scaled and planned with Gracey curettes 5/6 and 7/8. The second group, the roots samples were treated with ultrasonic instruments. The third group was irradiated with Er:YAG laser using 60 mJ/pulse , 10 Hz and energy density of 4 J/cm{sup 2} (approximated). The fourth group was irradiated with Er:YAG laser using 100 mJ/pulse, 10 Hz and energy density of 7 J/cm{sup 2} (approximated). The results analysis showed that roots scaling either with Gracey curettes or with ultrasonic instruments created smear layer covering roots surfaces; roots surfaces irradiated with Er:YAG laser showed few roughness in the third group; roots surfaces irradiated with Er:YAG laser showed no smear layer and the Er:YAG laser irradiation did not bring any

  8. Er:YAG laser ablation: evaluation after a two-year clinical treatment

    Dostalova, Tatjana; Jelinkova, Helena; Kucerova, Hana; Krejsa, Otakar; Hamal, Karel; Kubelka, Jiri; Prochazka, Stanislav


    The aim of the clinical study is to evaluate Er:YAG laser ablation after two year-long clinical treatment. One hundred fifty cavities were volunteered for checking. Three restorative materials were used following manufacturer's directions. For the experiment, an Er:YAG laser drilling machine was applied. The laser delivered energy from 100 to 450 mJ, repetition rate from 1 to 4 Hz. The length of the generated pulses was 200 microseconds. During our experiments cooling of the teeth was achieved by fine water mist. The number of pulses was from 16 to 489. Caries of enamel and dentin were treated. Old insufficient fillings were also removed (not amalgam or metal alloys). The experiments followed the guidelines of the Declaration of Helsinki (1964), Tokyo (1975), Venice (1983) and Hong-Kong (1989). Clinical evaluation of fillings after 6, 12, 18 and 24 months based on ADA recommendation was used. Eight criteria were applied for the restoration control. Composite resins and glassionomers could be used as filling materials.

  9. Relationship between the chemical and morphological characteristics of human dentin after Er:YAG laser irradiation.

    Soares, Luís Eduardo Silva; Martin, Ovídio César Lavesa; Moriyama, Lilian Tan; Kurachi, Cristina; Martin, Airton Abrahão


    The effects of laser etching on dentin are studied by microenergy-dispersive x-ray fluorescence spectrometry (μ-EDXRF) and scanning electron microscopy (SEM) to establish the correlation of data obtained. Fifteen human third molars are prepared, baseline μ-EDXRF mappings are performed, and ten specimens are selected. Each specimen received four treatments: acid etching (control-CG) or erbium:yttrium-aluminum-garnet (Er:YAG) laser irradiation (I-100 mJ, II-160 mJ, and III-220 mJ), and maps are done again. The Ca and P content are significantly reduced after acid etching (pmappings illustrated that acid etching created homogeneous distribution of inorganic content over dentin. Er:YAG laser etching (220 mJ) produced irregular elemental distribution and changed the stoichiometric proportions of hydroxyapatite, as showed by an increase of mineral content. Decreases and increases of mineral content in the μ-EDXRF images are correlated to holes and mounds, respectively, as found in SEM images.

  10. Human cornea wound healing in organ culture after Er:YAG laser ablation

    Shen, Jin-Hui; Joos, Karen M.; Robinson, Richard D.; Shetlar, Debra J.; O'Day, Denis M.


    Purpose: To study the healing process in cultured human corneas after Er:YAG laser ablation. Methods: Human cadaver corneas within 24 hours post mortem were ablated with a Q- switched Er:YAG laser at 2.94 micrometer wavelength. The radiant exposure was 500 mJ/cm2. The cornea was cultured on a tissue supporting frame immediately after the ablation. Culture media consisted of 92% minimum essential media, 8% fetal bovine serum, 0.125% HEPES buffer solution, 0.125% gentamicin, and 0.05% fungizone. The entire tissue frame and media container were kept in an incubator at 37 degrees Celsius and 5% CO2. Serial macroscopic photographs of the cultured corneas were taken during the healing process. Histology was performed after 30 days of culture. Results: A clear ablated crater into the stroma was observed immediately after the ablation. The thickness of thermal damage ranges between 1 and 25 micrometer. Haze development within the crater varies from the third day to the fourteenth day according to the depth and the roughness of the crater. Histologic sections of the cultured cornea showed complete re- epithelization of the lased area. Loose fibrous tissue is observed filling the ablated space beneath the epithelium. The endothelium appeared unaffected. Conclusions: The intensity and time of haze development appears dependent upon the depth of the ablation. Cultured human corneas may provide useful information regarding the healing process following laser ablation.

  11. Nd:YAG 1.44 laser ablation of human cartilage

    Cummings, Robert S.; Prodoehl, John A.; Rhodes, Anthony L.; Black, Johnathan D.; Sherk, Henry H.


    This study determined the effectiveness of a Neodymium:YAG 1.44 micrometers wavelength laser on human cartilage. This wavelength is strongly absorbed by water. Cadaveric meniscal fibrocartilage and articular hyaline cartilage were harvested and placed in normal saline during the study. A 600 micrometers quartz fiber was applied perpendicularly to the tissues with a force of 0.098 N. Quantitative measurements were then made of the ablation rate as a function of fluence. The laser energy was delivered at a constant repetition rate of 5 Hz., 650 microsecond(s) pulsewidth, and energy levels ranging from 0.5 joules to 2.0 joules. Following the ablation of the tissue, the specimens were fixed in formalin for histologic evaluation. The results of the study indicate that the ablation rate is 0.03 mm/mj/mm2 for hyaline cartilage and fibrocartilage. Fibrocartilage was cut at approximately the same rate as hyaline cartilage. There was a threshold fluence projected to be 987 mj/mm2 for hyaline cartilage and fibrocartilage. Our results indicate that the pulsed Nd:YAG laser operating at 1.44 micrometers has a threshold fluence above which it will ablate human cartilage, and that its ablation rate is directly proportional to fluence over the range of parameters tested. Fibrocartilage and hyaline cartilage demonstrated similar threshold fluence and ablation rates which is related to the high water content of these tissues.

  12. Nd:YAG laser hyaloidotomy for valsalva pre-macular haemorrhage.

    Kirwan, R P


    AIM: To report a case of successful drainage of a large pre-macular haemorrhage using laser photo-disruption of the posterior hyaloid membrane. MATERIALS AND METHODS: A case report. RESULTS: A 47-year-old man presented acutely to our emergency department complaining of a 24-h history of sudden onset, painless and persistent loss of vision in his left eye. Immediately before noticing this loss of vision, he had been vomiting violently from excessive alcohol intake. The left visual acuity was counting fingers. Dilated fundoscopy of the left eye revealed a large pre-macular haemorrhage which was 14 disc diametres in size. Clotting investigations were normal. A diagnosis of valsalva retinopathy was made and the patient elected to receive a prompt neodymium-doped yttrium aluminium garnet (Nd:YAG) laser posterior hyaloidotomy as an outpatient. At 1 week follow-up, the haemorrhage had drained completely into the vitreous space revealing a healthy macula and the visual acuity had improved to 6\\/12 unaided. At 6-month follow-up the left visual acuity stabilised at 6\\/9 unaided. CONCLUSION: Nd:YAG laser posterior hyaloidotomy is a useful outpatient procedure for successful clearance of large pre-macular haemorrhages that offers patients rapid recovery of visual acuity and the avoidance of more invasive intraocular surgery.

  13. Spectroscopic characterization of dynamical processes for Tm,Ho:YAG lasers

    Armagan, G.; Buoncristiani, A. M.; Edwards, W. C.; Inge, A. T.; Dibartolo, B.


    The energy transfer processes in Tm,Ho:YAG lasers were investigated in spectral studies and measurements of the temporal response to pulsed excitation. These processes include the population of the 3H4 pump band of Tm, cross-relaxation in Tm, the transfer of energy from Tm to Ho, and various loss mechanisms. It was found that the Tm cross-relaxation is due to a dipole-dipole interaction between Tm ions and that the rate of this process is a function of temperature and ion concentration.

  14. A 12.1-W SESAM mode-locked Yb:YAG thin disk laser

    Yingnan, Peng; Zhaohua, Wang; Dehua, Li; Jiangfeng, Zhu; Zhiyi, Wei


    Pumped by a 940 nm fiber-coupled diode laser, a passively mode-locked Yb:YAG thin disk oscillator was demonstrated with a semiconductor saturable absorber mirror (SESAM). 12.1 W mode-locked pulses were obtained with pulse duration of 698 fs at the repetition rate of 57.43 MHz. Measurement showed that the beam quality was close to the diffraction limit. Project supported by the National Key Basic Research Program of China (Grant No. 2013CB922402), the National Major Instrument Program of China (Grant No. 2012YQ120047), and the National Natural Science Foundation of China (Grant No. 61210017).

  15. Preliminary report on use of the neodymium-YAG laser in plastic surgery.

    Apfelberg, D B; Smith, T; Lash, H; White, D N; Maser, M R


    Thirty-four patients with 57 cutaneous lesions have been treated with the Nd:YAG laser under an experimental protocol over a year of study. The majority of treatments were done on an outpatient basis under local anesthesia. Capillary/cavernous hemangiomas of the oral cavity responded well, but hemangiomas of infancy responded poorly. Hypertrophic scars and keloids responded well only in conjunction with steroid treatment. Epistaxis in patients with hereditary hemorrhagic telangiectasia responded well for 4-5 months and then recurred. Areas with thin skin or mucosa have the potential for full-thickness injury with complications of scar, bony exposure, or septal perforation.

  16. Effects of output waveforms on penetration for Nd: YAG laser welding


    By using a Nd: YAG laser welding system devised for transmitting continuous, rectangular and pulsed waveforms, comprehensive and deep investigation is focused on the effects of several parameters of rectangular waveform and pulsed output wave superimposed on a rectangular waveform on the penetration depth of weld. Research results indicate that the average power, duty cycle, frequency and peak power of rectangular wave affect the weld penetration depth to different extent. Results of experiments and analysis also indicate that the pulse delay time, pulse width and the power ratio of pulse to rectangular waveform seriously influence the penetration when the pulsed wave is superimposed on a rectangular waveform.

  17. Application of YAG laser technique in the treatment of anal fistula

    Liu, Jian-xun; Zhang, Xinrong


    The method of treating anal fistula with YAG laser technique is described in this essay. One-hundred-twenty patients have been treated successfully with this method and no recurrence was found in our series. Anal fistula is a common disorder in the anus and rectum. The tunnel of fistula zigzags around the external or internal sphincters. If the drainage is poor, and the skin around the external opening grows rapidly, false healing may occur and cause recurrent abscess. In this case, a fistula can not be cured except by operation.

  18. Endoluminal non-contact soft tissue ablation using fiber-based Er:YAG laser delivery

    Kundrat, Dennis; Fuchs, Alexander; Schoob, Andreas; Kahrs, Lüder A.; Ortmaier, Tobias


    The introduction of Er:YAG lasers for soft and hard tissue ablation has proven promising results over the last decades due to strong absorption at 2.94 μm wavelength by water molecules. An extension to endoluminal applications demands laser delivery without mirror arms due to dimensional constraints. Therefore, fiber-based solutions are advanced to provide exible access while keeping space requirements to a minimum. Conventional fiber-based treatments aim at laser-tissue interactions in contact mode. However, this procedure is associated with disadvantages such as advancing decrease in power delivery due to particle coverage of the fiber tip, tissue carbonization, and obstructed observation of the ablation progress. The objective of this work is to overcome aforementioned limitations with a customized fiber-based module for non-contact robot-assisted endoluminal surgery and its associated experimental evaluation. Up to the authors knowledge, this approach has not been presented in the context of laser surgery at 2.94 μm wavelength. The preliminary system design is composed of a 3D Er:YAG laser processing unit enabling automatic laser to fiber coupling, a GeO2 solid core fiber, and a customized module combining collimation and focusing unit (focal length of 20 mm, outer diameter of 8 mm). The performance is evaluated with studies on tissue substitutes (agar-agar) as well as porcine samples that are analysed by optical coherence tomography measurements. Cuts (depths up to 3mm) with minimal carbonization have been achieved under adequate moistening and sample movement (1.5mms-1). Furthermore, an early cadaver study is presented. Future work aims at module miniaturization and integration into an endoluminal robot for scanning and focus adaptation.

  19. Graded Yb:YAG ceramic structures: design, fabrication and characterization of the laser performances

    Toci, Guido; Lapucci, Antonio; Ciofini, Marco; Esposito, Laura; Hostaša, Jan; Piancastelli, Andreana; Gizzi, Leonida A.; Labate, Luca; Ferrara, Paolo; Pirri, Angela; Vannini, Matteo


    Significant improvements in efficiency in high power, high repetition rate laser systems should come from the use of ceramic laser active elements suitably designed to mitigate the thermal and thermo-mechanical effects (TEs and TMEs) deriving from the laser pumping process. Laser active media exhibiting a controlled and gradual distribution of the active element(s) could therefore find useful applications in the laser-driven inertial confinement fusion systems, which are considered among the most promising energy source of the future (ultraintense laser pulses), and in medical applications (ultrashort laser pulses) The present work explores the flexibility of the ceramic process for the construction of YAG (Y3Al5O12) ceramic laser elements with a controlled distribution of the Yb doping, in view of the realization of structures modelled to respond to specific application. Two processing techniques are presented to prepare layered structures with a tailored modulation of the doping level, with the goal of reducing the peak temperature, the temperature gradients and also the thermally-induced deformation of the laser material, thus mitigating the overall thermal effects. Tape casting in combination with thermal compression of ceramic tapes with a varying doping level is one of the presented techniques. To make this process as more adaptable as possible, commercial micrometric ceramic powders have been used. The results are compared with those obtained using nanometric powders and a shaping process based on the subsequent pressing of spray dried powders with a different doping level. Laser performance has been characterized in a longitudinally diode pumped laser cavity. The laser efficiency under high thermal load conditions has been compared to those obtained from samples with uniform doping, and for samples obtained with press shaping and tape casting, under the same conditions.

  20. Pulsed Nd: YAG laser drilling of aerospace materials (Ti-6Al-4V)

    Bahar, N. D.; Marimuthu, S.; Yahya, W. J.


    This paper studies the influence of Nd:YAG (neodymium-doped yttrium aluminium garnet) laser process parameters on laser drilled hole quality. Ti-6Al-4V of 1 mm and 3 mm thickness were used as the workpiece substrate. The principal findings are mainly based on minimising the taper angle in laser drilled holes, reducing the heat affected zone and reducing the production of spatter. Identification of key process variables associated with laser drilling process is accomplished by trial experimentation. Using the identified key process variables, further experiments were then performed with the assistance of statistical design of experiment (DOE) to find the interaction and individual effects of various laser process parameters on laser drilled hole quality. The lowest taper angle of 1.8 degrees was achieved with use of nitrogen as the assist gas. Furthermore, from the laser process observations, it was found that laser power significantly affects the quality of the laser drilled hole. Increase in laser power would increase the hole size and result in more spatter on the entry hole surfaces. The nozzle focus position substantially influenced the laser drilled hole size. The amount of spatter deposits increased with decrease in the nozzle offset. Increase in laser frequency significantly increased the exit diameter, which resulted in smaller taper angle. Number of pulse required to drill through a workpiece depends on the material properties and physical properties of the material. For 1mm Ti-6Al-4V, a minimum of two pulses was required to successfully removed the material during drilling and a minimum of 4 pulses was required to drill through the same material with 3mm thickness.

  1. Compositional analysis of root cementum and dentin after Er:YAG laser irradiation compared with CO2 lased and intact roots using Fourier transformed infrared spectroscopy.

    Sasaki, K M; Aoki, A; Masuno, H; Ichinose, S; Yamada, S; Ishikawa, I


    The present study examines the dental root after Er:YAG laser irradiation, compared with CO2 lased and non-treated surfaces, using Fourier Transformed Infrared (FTIR) spectroscopy. Freshly extracted human teeth were irradiated by Er:YAG laser at an energy output of 40 mJ/pulse, 10 Hz (0.4 watts), with or without water coolant, and by CO2 laser at an energy output of 0.5 watts in continuous wave mode without coolant. The surfaces were chalky and smooth after irradiation by Er:YAG laser with water coolant, were charred and irregular after irradiation by Er:YAG laser without water coolant, and were completely carbonized after CO2 laser irradiation. The FTIR profiles from samples of the surfaces that were irradiated by Er:YAG laser with water coolant were similar to those from non-treated samples, except for a slight decrease on the OH and amide bands, which are mainly related to organic components. This decrease was observed to be extreme after CO2 laser irradiation and moderate after Er:YAG laser irradiation without coolant. The formation of new bands showing toxic substances was observed to a large extent after CO2 laser irradiation and to a smaller extent after Er:YAG laser irradiation without water coolant. In contrast, no such bands were detected after Er:YAG laser irradiation with water coolant. The present results show that these laser treatments selectively ablated more organic components than inorganic components and that Er:YAG laser irradiation with water coolant did not cause major compositional changes or chemically deleterious changes in either root cementum or dentin.

  2. Thomson Experiment

    This experiment, conducted by JJ Thomson in 1897, established the existence of the electron. Thomson won the Nobel physics prize for this work in 1906. A beam of electrons crosses the chamber emitting blue light. Adding an electric field (E) or a magnetic field (B) exerts a force on the moving electrons.Use switch E to turn on the electric field in the chamber. Then, by turning knob B, you can increase the current in the coils, generating a magnetic field. By balancing the electric and magnetic fields, Thomson was able to keep the electron beam level and deduce the ratio of the electron's charge to its mass.

  3. Evaluation of depth and profile cavity after laser ablation with different energy of Er:YAG laser radiation

    Dostalova, Tatjana; Jelinkova, Helena; Hamal, Karel; Krejsa, Otakar; Kubelka, Jiri; Prochazka, Stanislav


    Depth and profile cavity were studied after laser ablation with different energy of Er:YAG laser beam. Longitudinal sections of extracted human teeth were cut and polished to the flat surfaces. The thickness of layer of prepared teeth was from 3 to 5 mm. The check group contained glazed samples of ivory with the similar thickness. The Er:YAG laser drilling machine was operating in a free-running mode. For the preparation we used the energy up to 500 mJ. The repetition rate was 1 or 2 Hz. The laser radiation was focused on the tooth surface using CaF2 lens (f equals 55 mm). During the experiment, teeth were steady and the radiation was delivered by the mechanical arm which was fixed in a special holder. The fine water mist (water - 50 ml/min with the pressure to atm, air-pressure three atm) was used. Samples with the flat surfaces from the enamel, dentin and ivory were irradiated with five different energies from 100 to 500 mJ. Quantities of one, five, ten, twenty and thirty pulses were used. The depth of cavity and its profile were observed and measured. It was found that depth of cavity depends on the value of energy, type of hard dental tissue and number of pulses. With increasing energy or number of pulses the saturation effect in depth of holes in dentine or enamel were proved.

  4. Femtosecond-laser inscribed double-cladding waveguides in Nd:YAG crystal: a promising prototype for integrated lasers.

    Liu, Hongliang; Chen, Feng; Vázquez de Aldana, Javier R; Jaque, D


    We report on the design and implementation of a prototype of optical waveguides fabricated in Nd:YAG crystals by using femtosecond-laser irradiation. In this prototype, two concentric tubular structures with nearly circular cross sections of different diameters have been inscribed in the Nd:YAG crystals, generating double-cladding waveguides. Under 808 nm optical pumping, waveguide lasers have been realized in the double-cladding structures. Compared with single-cladding waveguides, the concentric tubular structures, benefiting from the large pump area of the outermost cladding, possess both superior laser performance and nearly single-mode beam profile in the inner cladding. Double-cladding waveguides of the same size were fabricated and coated by a thin optical film, and a maximum output power of 384 mW and a slope efficiency of 46.1% were obtained. Since the large diameters of the outer claddings are comparable with those of the optical fibers, this prototype paves a way to construct an integrated single-mode laser system with a direct fiber-waveguide configuration.

  5. Effects of Er:YAG laser on bond strength of self-etching adhesives to caries-affected dentin.

    Koyuturk, Alp Erdin; Ozmen, Bilal; Cortcu, Murat; Tokay, Ugur; Tosun, Gul; Erhan Sari, Mustafa


    The erbium:yttrium-aluminum-garnet (Er:YAG) laser may be effective the bond strength of adhesive systems on dentine surfaces, the chemical composition and aggressiveness of adhesive systems in clinical practice. The purpose of this study was to evaluate the effects of the Er:YAG laser system with the bonding ability of two different self-etching adhesives to caries-affected dentine in primary molars. Ninety mid-coronal flat dentine surfaces obtained from sound and caries-affected human primary dentine were treated with an Er:YAG laser or a bur. The prepared surfaces were restored with an adhesive system (Xeno V; Clearfil S³) and a compomer (Dyract Extra). The restored teeth were sectioned with a low-speed saw and 162 samples were obtained. The bond strength of the adhesive systems was tested using the micro-tensile test method. The data were statistically analyzed. A restored tooth in each group was processed for scanning electron microscopy evaluation. The values of the highest bond strength were obtained from the Clearfil S³-Er:YAG laser-sound dentine group in all groups. (24.57 ± 7.27 MPa) (P > 0.05). The values of the lowest bond strength were obtained from the Xeno V-Er:YAG laser-sound dentine group in all groups (11.01 ± 3.89 MPa). It was determined that the Clearfil S³ increased the bond strength on the surface applied with Er:YAG laser according to the Xeno V. Copyright © 2014 Wiley Periodicals, Inc.

  6. Direct laser writing of near-IR step-index buried channel waveguides in rare earth doped YAG.

    Rodenas, A; Benayas, A; Macdonald, J R; Zhang, J; Tang, D Y; Jaque, D; Kar, A K


    A new (to our knowledge) ultrashort laser pulse irradiation regime that allows us to directly modify and increase the refractive index of rare earth doped YAG polycrystalline ceramics has been identified. Single-mode buried channel waveguides in both Ho:YAG and Er:YAG ceramics at the near-IR wavelengths of 1.55 μm and 1.95 μm are demonstrated by fabricating positive square step-index cores. Minimum propagation losses of 1.5 dB cm(-1) at a 1.51 μm wavelength have been preliminarily obtained. Confocal microluminescence mapping reveals that the increased refractive index regions retain the near-IR spectral properties of Er3+ ions in the YAG crystalline matrix.

  7. Characterization of 1064 nm Nd:YAG laser-produced cu plasma

    Ilyas, B.; Dogar, A. H.; Ullah, S.; Nadeem, A.; Qayyum, A.


    The plasma was produced by focusing Nd:YAG laser pulses of 1064 nm wavelength on to a copper target at laser fluences of 5.35, 6.95, and 9.33 J/cm2. An ion collector placed along the target surface normal was used to record the time-of-flight (TOF) ion signal during plasma expansion in vacuum. The TOF ion pulses were deconvoluted using the Coulomb-Boltzmann-shifted function to estimate the available Cu ion charge states, equivalent plasma ion temperature, and accelerating potential in the nonequilibrium plasma. The maximum available ion charge state, equivalent plasma ion temperature, and accelerating potential are found to increase with laser fluence. In the local thermal equilibrium conditions, the accelerating potential can be supposed to apply across a distance of the order of the Debye length. The Debye length and, hence, the electric field in the laser produced plasma at three laser fluences values were estimated. The electric field was in the range of 1 MV/cm and increased with laser fluence. In the laser fluence range used in this work, the sum of thermal and adiabatic energy of the ion was slightly higher than its Coulomb energy.

  8. Experimental and theoretical investigation of the drilling of alumina ceramic using Nd:YAG pulsed laser

    Hanon, M. M.; Akman, E.; Genc Oztoprak, B.; Gunes, M.; Taha, Z. A.; Hajim, K. I.; Kacar, E.; Gundogdu, O.; Demir, A.


    Alumina ceramics have found wide range of applications from semiconductors, communication technologies, medical devices, automotive to aerospace industries. Processing of alumina ceramics is rather difficult due to its high degree of brittleness, hardness, low thermal diffusivity and conductivity. Rapid improvements in laser technologies in recent years make the laser among the most convenient processing tools for difficult-to-machine materials such as hardened metals, ceramics and composites. This is particularly evident as lasers have become an inexpensive and controllable alternative to conventional hole drilling methods. This paper reports theoretical and experimental results of drilling the alumina ceramic with thicknesses of 5 mm and 10.5 mm using milisecond pulsed Nd:YAG laser. Effects of the laser peak power, pulse duration, repetition rate and focal plane position have been determined using optical and Scanning Electron Microscopy (SEM) images taken from cross-sections of the drilled alumina ceramic samples. In addition to dimensional analysis of the samples, microstructural investigations have also been examined. It has been observed that, the depth of the crater can be controlled as a function of the peak power and the pulse duration for a single laser pulse application without any defect. Crater depth can be increased by increasing the number of laser pulses with some defects. In addition to experimental work, conditions have been simulated using ANYS FLUENT package providing results, which are in good agreement with the experimental results.

  9. Equation-of-state studies using a 10-Hz Nd:YAG laser oscillator

    Shukla, M.; Upadhyay, A.; Senecha, V. K.; Khare, P.; Bandyaopadhyay, S.; Rai, V. N.; Navathe, C. P.; Pant, H. C.; Khan, M.; Godwal, B. K.


    A commercial mode locked cavity dumped Nd:YAG dye laser operating at 10 Hz repetition rate is modified to produce a high contrast (>5000:1) single laser pulse while maintaining the energy stability and high beam quality. A trigger generator biases the cavity dumping photodiode, which is triggered externally by a pulse from the microprocessor-based control unit controlling a [similar]2 J/200 ps laser chain. In the laser chain, the high contrast (>5000:1) is achieved by an external pulse selector based on single Pockel's cell to select a single laser pulse of high contrast, which is a prerequisite for experimental study of the equation of state. Laser-induced shock velocity measurement in thin aluminum, gold on aluminum, and copper on aluminum foil targets using this modified laser system are also presented. The equation of state of Al, Au, and Cu obtained using an impedance matching technique are in agreement with the reported results of SESAME and simulation results.

  10. Microbial contamination in dental unit waterlines: comparison between Er:YAG laser and turbine lines.

    Sacchetti, Rossella; Baldissarri, Augusto; De Luca, Giovanna; Lucca, Paola; Stampi, Serena; Zanetti, Franca


    The investigation was carried out by evaluating the microbiological characteristics of the water before and after treatment with Er:YAG laser and turbine. The study was carried out in 2 dental surgeries. In both cases the laser and dental units were served by two independent circuits, fed by the same potable tap water. Samples were taken from the water supplying and the water leaving the turbine and laser before and after treatment on the same patient. Total heterotrophic plate count was measured at 36 degrees C and at 22 degrees C, and the presence of Staphylococcus species and non-fermenting Gram negative bacteria was investigated. Bacterial contamination was found within the circuit, especially in the laser device. Pseudomonas aeruginosa was detected in only 1 sample of supply water, in 11.1 % and in 19.4 % of the samples from the turbine and the laser respectively. No evidence of Staphylococcus aureus was found. The contamination of supply water was low, whereas that of the water leaving the handpieces of the 2 devices was high, especially in the laser. Attention should be paid to the control of the water leaving laser devices, given the increasingly wide use of such instruments in dental treatment exposed to risk of infection.

  11. Reducing temperature dependence of the output energy of a quasi-continuous wave diode-pumped Nd:YAG laser.

    Lee, Kangin; Kim, Youngjung; Lee, Sijin; Kwon, Jin Hyuk; Gwak, Jin Seog; Yi, Jonghoon


    It is demonstrated by numerical modeling that spectrally dispersed compound pumping diodes and low-loss pumping chamber reduced the temperature dependence of the output energy of quasi-continuous wave diode-pumped Nd:YAG lasers considerably. Several compound diodes with different spectral profiles were tested for pumping. The laser energy was calculated as a function of diode temperature from -30°C to 60°C. When a compound diode with a flat-top spectrum was used for pumping, the mean laser energy was 83% of the maximum energy of a Nd:YAG laser pumped by a diode with a narrow bandwidth. In addition, a compound diode with three emission lines was tested for pumping. When the wavelength gap between the adjacent emission lines of the pumping diode was in the range of 3-10 nm, the mean energy of the Nd:YAG laser became similar to that of a Nd:YAG laser pumped by a diode with a flat-top spectrum.

  12. Effect of Fluoride Varnish Combined with Er:YAG Laser on the Permeability of Eroded Dentin: An In Situ Study

    Nemezio,Mariana Alencar; Carvalho,Sandra Chiga; Scatolin, Renata Siqueira; Colucci,Vivian; Galo, Rodrigo; Corona, Silmara Aparecida Milori


    This study evaluated the combined effect of fluoride varnish and Er:YAG laser on the permeability of eroded bovine root dentin. After initial erosive challenge followed by a remineralization period, the specimens were divided in two groups according to the treatment - fluoride varnish and non-fluoride varnish - and were subdivided according to the irradiation protocol: Er:YAG laser (100 mJ, 3 Hz, 12.8 J/cm2per pulse, non-contact and defocus mode) and non-irradiated. After a lead-in period, 7 ...

  13. Effect of an Indirect Composite Resin Surface Treatment with Two Types of Lasers: Nd: YAG, Er:YAG and Acid Etching on the Microshear Bond Strength of a Resin Cement


    Introduction: In order to increase the bonding strength of the composite resin cements to the indirect composites, experiments such as the creation of surface roughness with sandblasting, acid-etching, silane application, laser, etc. have been carried out. However, there is no consensus about the results. Therefore, the purpose of this study was to investigate the effect of Er: YAG and Nd: YAG lasers and acid etching on microshear bond strength of an indirect composite resin. Methods: Aft...

  14. Study of cavitation bubble dynamics during Ho:YAG laser lithotripsy by high-speed camera

    Zhang, Jian J.; Xuan, Jason R.; Yu, Honggang; Devincentis, Dennis


    Although laser lithotripsy is now the preferred treatment option for urolithiasis, the mechanism of laser pulse induced calculus damage is still not fully understood. This is because the process of laser pulse induced calculus damage involves quite a few physical and chemical processes and their time-scales are very short (down to sub micro second level). For laser lithotripsy, the laser pulse induced impact by energy flow can be summarized as: Photon energy in the laser pulse --> photon absorption generated heat in the water liquid and vapor (super heat water or plasma effect) --> shock wave (Bow shock, acoustic wave) --> cavitation bubble dynamics (oscillation, and center of bubble movement , super heat water at collapse, sonoluminscence) --> calculus damage and motion (calculus heat up, spallation/melt of stone, breaking of mechanical/chemical bond, debris ejection, and retropulsion of remaining calculus body). Cavitation bubble dynamics is the center piece of the physical processes that links the whole energy flow chain from laser pulse to calculus damage. In this study, cavitation bubble dynamics was investigated by a high-speed camera and a needle hydrophone. A commercialized, pulsed Ho:YAG laser at 2.1 mu;m, StoneLightTM 30, with pulse energy from 0.5J up to 3.0 J, and pulse width from 150 mu;s up to 800 μs, was used as laser pulse source. The fiber used in the investigation is SureFlexTM fiber, Model S-LLF365, a 365 um core diameter fiber. A high-speed camera with frame rate up to 1 million fps was used in this study. The results revealed the cavitation bubble dynamics (oscillation and center of bubble movement) by laser pulse at different energy level and pulse width. More detailed investigation on bubble dynamics by different type of laser, the relationship between cavitation bubble dynamics and calculus damage (fragmentation/dusting) will be conducted as a future study.

  15. Cooperative Clinical Trial of Photodynamic Therapy for Early Gastric Cancer With Photofrin Injection® and YAG-OPO Laser

    Seishiro Mimura; Hiroyuki Narahara; Toshio Hirashima; Hisayuki Fukutomi; Akira Nakahara; Hiromasa Kashimura; Hirofumi Matsui; Hiroshi Tanimura; Yugo Nagai; Shigeru Suzuki; Yoko Murata; Kazunari Yoshida; Kaichi Isono; Teruo Kozu; Hiroko Ide


    Background and Objective: Photodynamic therapy (PDT) treats malignant tumors using photosensitizers and light. We employed a new pulse laser as the excitation light source for PDT, i.e. an optical parametric oscillator (OPO) system pumped by a Q-switched Nd:YAG laser, because it provides extremely high peak power. Study Design/Materials and Methods: The effects of PDT using the photosensitizer Photofrin® and the new laser were evaluated in 12 patients with early gastric cancer. Results: Compl...

  16. Micromorphology and adhesive performance of Er:YAG laser-treated dentin of primary teeth.

    Flury, Simon; Koch, Tamara; Peutzfeldt, Anne; Lussi, Adrian


    This study evaluated (1) the micromorphology by scanning electron microscopy (SEM) and (2) the adhesive performance by microtensile bond strength (μTBS) of diamond bur-treated dentin compared to Er:YAG laser-treated dentin of human primary teeth. (1) For qualitative SEM evaluation, dentin of 18 second primary molars (n = 3/method) was treated with either diamond bur as a control (group 1a: 40 μm diamond bur only (clinical situation); group 1b: grinding + 40 μm diamond bur) or with Er:YAG laser (group 2a (clinical situation, manufacturer's settings): 200 mJ/25 Hz (5 W) + 100 mJ/35 Hz (3.5 W) laser only; group 2b (experimental setting "high"): grinding + 400 mJ/20 Hz (8 W); group 2c (manufacturer's setting "finishing"): grinding + 100 mJ/35 Hz (3.5 W); group 2d (experimental setting "low"): grinding + 50 mJ/35 Hz (1.75 W)). (2) For evaluation of adhesive performance, 64 second primary molars were divided into four groups and treated as described for group 1b and groups 2b/c/d (n = 16/method), and μTBS of Clearfil SE/Clearfil Majesty Esthetic to dentin was measured. The SEM micrographs were qualitatively analyzed. The μTBS values were compared with a Kruskal-Wallis test. The significance level was set at α = 0.05. SEM micrographs showed the typical micromorphologies with a smear layer for the diamond bur groups and open dentin tubules for all laser-treated groups. However, in group 2d, the laser beam had insufficiently irradiated the dentin area, rendering the underlying ground surface partly visible. There were no statistically significant differences between μTBS values of the four groups (p = 0.394). This suggests that Er:YAG laser treatment of dentin of primary molars provides bond strengths similar to those obtained following diamond bur treatment.

  17. An Auto-Fluorescence guided surgical approach performed with Er:YAG laser and Nd:YAG Low Level Laser Therapy for Medication-Related Osteonecrosis of the Jaw

    Ilaria Giovannacci


    Full Text Available Medication-Related Osteonecrosis of the Jaw (MRONJ therapy remains an unresolved problem. The proposed conservative and surgical treatment regimens are associated to contradictory success rates. Surgical approach with Er:YAG laser is associated to significant better results compared to medical treatment and traditional surgical approaches. Objective: To describe a new surgical approach that couples the advantages of the Er:YAG laser and the usefulness of the AF in highlighting surgical margins. One of the difficulties encountered during surgical removal of a MRONJ is the precise individuation of necrotic bone margins. Case Report: A case of Stage III mandibular osteonecrosis treated with a new surgical approach is presented. The aim is to describe an auto-fluorescence (AF guided surgical approach performed with Er:YAG laser and Nd:YAG Low Level Laser Therapy (LLLT. After one month of follow-up, the complete mucosal healing was evident and symptoms was unobserved. Such a technique allowed a highly accurate and minimally invasive approach through the selective ablation of the non-/hypofluorescent areas. Conclusion: Taking into account the advantages of laser therapy and the possible effectiveness of the AF in highlighting surgical margins, this approach would probably achieve excellent outcomes.DOI: 10.14693/jdi.v22i2.486

  18. Root planing with Er:YAG laser X Gracey curette, a study in vitro in scanning electron microscopic study; Avaliacao em microscopia eletronica de varredura da superficie radicular, raspada e alisada com Er: YAG laser

    Mello, Fabiano Augusto Sfier de


    The Er:YAG laser has been studied as a periodontal therapies, used to remove subgingival calculus and its bactericidal effects. The proposal of this study is to evaluate the effectiveness of the Er:YAG laser in root planing in comparison to the traditional method, not surgical. Six recently extracted due to the disease periodontal, were cut longitudinally, tends like this two half of the root. These half were separate in four groups. The first group is the natural tooth (group controls negative), the second group (group controls) was accomplished to root planing with Gracey curette. And in the third to Er:YAG laser with a contact tip, using a 45 deg angle in relation to the root; in the fourth group was scraped and planned with Er:YAG laser and complemented root planing with Gracey curette. The used energy was of 100 mJ (out put) and the frequency of 10 Hz accomplished with irrigation. The obtained results were similar in the groups 2 and 3 in comparison to the amount of smear-layer. In group 4 however, better result was obtained, because the image (SEM) was much more regular and with less amount of smear-layer. The conclusion of the work is that with the association of the laser technique and Gracey curette the results are superior to the conventional treatment. (author)

  19. Effect of laser-assisted bleaching with Nd:YAG and diode lasers on shear bond strength of orthodontic brackets.

    Mirhashemi, Amirhossein; Emadian Razavi, Elham Sadat; Behboodi, Sara; Chiniforush, Nasim


    The aim of the present study was to assess the effect of laser-assisted bleaching with neodymium:yttrium-aluminum-garnet (Nd:YAG) and diode lasers on shear bond strength (SBS) of orthodontic brackets. One hundred and four extracted human premolars were randomly divided into four groups: group 1: No bleaching applied (control group); group 2: Teeth bleached with 40 % hydrogen peroxide; group 3: Teeth treated with 30 % hydrogen peroxide activated with Nd:YAG laser (1064 nm, 2.5 W, 25 Hz, pulse duration of 100 μs, 6 mm distance); and group 4: Teeth treated with 30 % hydrogen peroxide activated with diode laser (810 nm, 1 W, CW, 6 mm distance). Equal numbers of teeth in groups 2, 3, and 4 were bonded at start, 1 h, 24 h, and 1 week after bleaching. A universal testing machine measured the SBS of the samples 24 h after bonding. After bracket debonding, the amount of residual adhesive on the enamel surface was observed under a stereomicroscope to determine the adhesive remnant index (ARI) scores. The SBS in the unbleached group was significantly higher than that in the bleached groups bonded immediately and 1 h after laser-assisted bleaching (P laser-assisted bleaching, the SBS was found to be significantly lower than that in the control group. Significant differences in the ARI scores existed among groups as well. The SBS of brackets seems to increase quickly within an hour after laser-assisted bleaching and 24 h after conventional bleaching. Thus, this protocol can be recommended if it is necessary to bond the brackets on the same day of bleaching.

  20. Heldi Thomson


    Teaduspreemia autorite kollektiivile arstiteaduse alal töö "Vähktõbi Eestis 1968-1992: haigestumus, levimus, elulemus ja suremus" eest - Mati Rahu (kollektiivi juht), Tiiu Aarelaid, Kaja Gornoi, Heldi Thomson