Showing papers on "Ruby laser published in 1989"
TL;DR: In this article, the emission characteristics of laser-induced plasma, with the use of a Q-switched ruby laser of 1.5 J, were studied in argon atmosphere at reduced pressure.
Abstract: The emission characteristics of laser-induced plasma, with the use of a Q-switched ruby laser of 1.5 J, were studied in argon atmosphere at reduced pressure. The time- and spatially resolved emission profiles were measured. In argon atmosphere at reduced pressure, the emission period of plasma is elongated to over a hundred microseconds, and the emissive region expands to more than a few tens of millimeters above the sample surface. The emission intensities of atomic lines increase severalfold in an argon atmosphere, in comparison with those obtained in air at the same pressure. Moderate confinement of plasmas and a resultant increase of emission intensities are achieved at 50 Torr. These results are explained by the chemical inertness and the thermal characteristics of the argon atmosphere and the decrease in absorption of the laser pulse by the plasma plume. The re-excitation of emissive species by collisions with metastable argon atoms seems to be less important.
72 citations
TL;DR: In this paper, a nanosecond ruby laser with a detection system (a polychromator, an image intensifier and a linear position-sensitive detector) controlled by a microcomputer was constructed.
Abstract: Combining a nanosecond ruby laser with a detection system (a polychromator, an image intensifier and a linear position‐sensitive detector) controlled by a microcomputer, a convenient laser photolysis system has been constructed. Operating the image intensifier in gated or continuous mode, the time‐resolved absorption and emission spectra from the nanosecond to millisecond time regime can be recorded very easily by one or two excitation laser shots. The spectral resolution is 2.5 nm, while the shortest temporal resolution is 10 ns. Also, by simply turning a mirror in the polychromator, the multiple‐component decays of transient absorptions, fluorescences, and phosphorescences can be analyzed by means of a combination of a photomultiplier with an oscilloscope controlled by a microcomputer.
45 citations
TL;DR: In this article, the authors obtained Si 1- x Ge x /Si crystalline films via pulsed laser annealing of Ge-implanted silicon crystals, which were implanted in random geometry with 150 keV 74 Ge ions at doses of 5 × 10 16 and 10 17 ions cm -2 (17 at% maximum concentration).
41 citations
TL;DR: An unpredicted wavelength dependence of the injury threshold for single Q-switched pulses is demonstrated and there is no complete or obvious explanation for the significant variations of threshold with small changes in wavelength.
Abstract: Thresholds for laser chorioretinal injury in the red end of the visible spectrum and the near-infrared (IR-A) spectral regions are presented. An unpredicted wavelength dependence of the injury threshold for single Q-switched pulses is demonstrated. Four lasers were used to determine thresholds at 40 wavelengths between 532 nm and 1064 nm: a ruby laser, a neodymium:YAG-pumped dye laser, an erbium:YLF laser and an alexandrite laser. Despite many careful and repeated efforts to determine a cause for the variation due to possible variations in the lasers or other aspects of the experimental technique and due to biological absorption properties of the eye, there is no complete or obvious explanation for the significant variations of threshold with small changes in wavelength. The implications of these findings for laser safety standards are presented.
40 citations
TL;DR: In this paper, the dependence of the film properties on laser energy density, oxygen partial pressure during deposition and substrate bias has been investigated and optimum conditions have been brought out for obtaining single phase stoichiometric thin films.
37 citations
TL;DR: In this article, a data-treatment procedure was proposed for more accurate determination of electron temperatures and electron concentrations in analytical plasmas. But the method is not suitable for the measurement of electron energy.
34 citations
TL;DR: In this paper, thin films of boron nitride (500-1000A) were deposited on InP using a Q-switched ruby laser, and the minimum interface state density for the Al/BN/InP system was 6.2 × 1010 cm-2-1 0.5 below the conduction band.
Abstract: Thin films of boron nitride (500–1000A) were deposited on InP using a Q-switched ruby laser. Films were found to have a dielectric constant of 3.28, resistivity of 5 ×1011Ωcm and bandgap of 4.1eV. The minimum interface state density for the Al/BN/InP system was 6.2 × 1010 cm-2-1 0.5 below the conduction band.
17 citations
01 Dec 1989
TL;DR: In this paper, the nonlinear refractive index of benzene was determined by measuring the reduction of the beam divergence of picosecond ruby laser pulses when passing through a benzene sample.
Abstract: The nonlinear refractive index of benzene is determined by measuring the reduction of the beam divergence of picosecond ruby laser pulses when passing through a benzene sample. Time-integrated spatial beam profiles give an effective refractive index while time-resolved beam profiles measured with a streak camera allow the determination of the temporal evolution of the nonlinear refractive index.
14 citations
TL;DR: In this paper, the primary aberrations in standard in-line Fraunhofer holography with collimated beams of different recording and reconstruction wavelengths are described, and Marechal's criterion is then applied to establish the aberration limited size resolution of micro-objects.
Abstract: The primary aberrations in standard in-line Fraunhofer holography with collimated beams of different recording and reconstruction wavelengths are described. Marechal's criterion is then applied to establish the aberration limited size resolution of micro-objects. The resolution is described in terms of the recording and reconstruction wavelengths, the number of side lobes recorded, and the number of far-field distances. The particular case of a ruby laser recording with reconstruction by a HeNe laser is discussed in detail.
11 citations
TL;DR: Spectra from plasmas produced by focusing the output of a Q-switched ruby laser onto planar targets of metallic strontium have been photographed in the 40-500 AA region as mentioned in this paper.
Abstract: Spectra from plasmas produced by focusing the output of a Q-switched ruby laser onto planar targets of metallic strontium have been photographed in the 40-500 AA region. Lines arising from 4p-5s transitions in Sr VI and Sr VII have been identified. From the line profiles it is possible to estimate the mean kinetic energy of these particular ionic species in the plasma.
10 citations
TL;DR: In this article, the effect of changes in the initial thicknesses of poly Si and SiO2 layers on the duration of the melt on the SiO 2 surface, which determines the crystal growth, was analyzed.
TL;DR: In this article, the edge plasma density versus plasma radius function of the MT-1 Tokamak plasma is measured by a new laser blow-off method, where a thin film of sodium evaporated on a glass substrate is brown off by a Q-switched ruby laser pulse.
Abstract: The edge plasma density versus plasma radius function of the MT-1 Tokamak plasma is measured by a new laser blow-off method. A thin film of sodium evaporated on a glass substrate is brown off by a Q-switched ruby laser pulse. The enhanced shortening of the pulse of neutrals was observed along the beam propagation toward the plasma center by measuring the resonance light intensity of atoms excited by the plasma electrons. The density of the plasma is calculated from the measured exponential time decay of the blow-off-light pulse without any further calibrating measurements.
TL;DR: In this paper, the dynamics of a ruby laser pumped by a CW argon-ion laser is studied and the conditions needed for instability are discussed and homodyne spectra and temporal maps of the phase space attractors are obtained.
Abstract: A study of the dynamics of a ruby laser pumped by a CW argon-ion laser is presented. The ruby laser is predominantly stable but has two accessible unstable states. One state exhibits chaotic output, while the other results in regular self-pulsing. The conditions needed for instability are discussed and homodyne spectra and temporal maps of the phase-space attractors are obtained. In addition, a numerical simulation of nonlinear beam propagation in ruby is presented that shows that strong deviations from plane-wave behavior exist, and that transverse effects must be incorporated into theoretical models of the instability.
TL;DR: In this paper, the first observation of the Thomson scattering signals from ruby laser light from an excimer laser was made, and the results revealed the structure of the electron temperature, such as an increase of the temperature when the buffer gas was changed from helium to neon.
Abstract: The electron velocity distribution function is the key parameter for understanding chemical kinetics in plasmas of discharge-pumped excimer lasers. Local and unambiguous determination of the parameter is presently only possible by the Thomson scattering, and this letter describes the first observation of the Thomson scattering signals from ruby laser light from an excimer laser. The results revealed otherwise inaccessible structure of the electron temperature, such as an increase of the temperature when the buffer gas was changed from helium to neon.
TL;DR: The grating-like spatially periodic structures are produced on the (100) surfaces of the single crystal silicon by the trains of 10 ps mode-locked ruby laser pulses at the wavelength of 694.3 nm as discussed by the authors.
Abstract: The grating-like spatially periodic structures are produced on the (100) surfaces of the single crystal silicon by the trains of 10 ps mode-locked ruby laser pulses at the wavelength of 694.3 nm. The periods and orientations of the structures are consistent with the model which involves the interference of the incident light with the surface electromagnetic wave excited through the coupling by surface roughness. Previously unappreciated elliptic ripple patterns are found and explained as the trails of the capillary wave excited on the molten Si surface due to the radially non-uniform deposition of energy.
TL;DR: In this article, a Q-switched ruby laser, focused by means of a spherical-cylindrical lens combination, was used to irradiate massive planar carbon targets.
Abstract: A Q-switched ruby laser, focused by means of a spherical-cylindrical lens combination, was used to irradiate massive planar carbon targets. Intensity on target was maintained at 4*109 W cm-2 as the line focus length-to-width aspect ratio was varied. Measurements made with charge-collecting Faraday cups indicate a collimation of both integrated ion number flux and total ion energy in a plane orthogonal to the laser line focus length, the extent of collimation being dependent upon the line focus aspect ratio. Results are compared with a simple axisymmetric potential fluid flow model.
Journal Article•
TL;DR: A technique whereby a laser beam is converted to have a square and uniform output intensity distribution and emerges with a uniform intensity distribution over the cross-section at the end of the pillar is developed.
Abstract: Laser beams have been in common use for the treatment of hyperpigmented skin lesions. However, therapeutic efficacy has been limited mainly because the output is circular with a Gaussian distribution of intensity, which makes it difficult to apply a uniformly distributed dose to the lesions. We have developed a technique whereby a laser beam is converted to have a square and uniform output intensity distribution. The principle of this technique is that the divergent laser beam enters a glass square pillar, propagates through the pillar repeating the total reflection and emerges with a uniform intensity distribution over the cross-section at the end of the pillar. The device applied this technique is incorporated in a hand-piece and both ruby and argon laser systems have been developed. The ruby laser has been used for the treatment of the melanistic skin lesions such as nevus cell nevus and nevus spilus. In clinical application, 36 of 67 cases have shown remarkably effective results with an improvement rate of 53.7%. The argon laser has been used for the treatment of vasogenic skin lesions such as portwine stain. In clinical application, 44 of 66 cases have shown effective results and the improvement rate is 66.7%. These results are excellent when compared with the other methods of treatment and with laser therapy previously used.
10 Apr 1989
TL;DR: In this article, a single-step technique for local deposition of compound films with lateral dimensions down to the micrometer range from a multilayer structure on a transparent support as a source is presented.
Abstract: A systematic study on ruby laser processing of supported Ge/Se bilayer structures is reported. Depending on the sequence of the initial layers and processing parameters compound synthesis, total or partial ablation of one of the constituents or the compound formed and simultaneous transfer of the ablated material onto a separate substrate in close proximity is possible with one single laser pulse. The results establish a novel single step technique for local deposition of compound films with lateral dimensions down to the micrometer range from a multilayer structure on a transparent support as a source.
TL;DR: In this article, a theoretical analysis of the dynamics of intracavity Raman scattering and its influence on mode locking in a master laser was made on the basis of a spectral-mode description of the field in the resonator.
Abstract: Intracavity stimulated Raman scattering (STRS) in a cell containing compressed hydrogen placed inside a ruby laser resonator with active mode locking was investigated using an additional high-Q resonator locked to the frequency of the first Stokes component. A theoretical analysis of the dynamics of intracavity STRS and of its influence on mode locking in a master laser was made on the basis of a spectral–mode description of the field in the resonator. It was found that, depending on the nonlinear interaction between the modes governed by the hydrogen pressure and the length of a laser cell, it is possible to establish weak, optimal, or strong energy exchange between the laser and Stokes waves. An experimental study of STRS at various hydrogen pressures confirmed the calculations and showed that feedback at the Stokes frequency reduced the STRS threshold and increased the conversion efficiency.
TL;DR: The emission spectra of a laser plasma formed from tungsten were determined in the ultrasoft x-ray range (photon energy 60-130 eV) when the power density of the laser radiation was 30 GW/cm2 (ruby laser) of 5 and 2 GW/ cm2 (XeCl laser) as discussed by the authors.
Abstract: The emission spectra of a laser plasma formed from tungsten were determined in the ultrasoft x-ray range (photon energy 60–130 eV) when the power density of the laser radiation was 30 GW/cm2 (ruby laser) of 5 and 2 GW/cm2 (XeCl lasers).
31 Mar 1989
TL;DR: In this article, a frequency-doubled Nd:YAG laser with an unstable resonator is explored for its capabilities as a coherent light source for, holographicmeasurements.
Abstract: A frequency-doubled Nd:YAG laser with an unstable resonator is explored for its capabilities as a coherent light source for, holographicmeasurements. Test objects are cavitation nuclei (small air bubbles and particles in water) whose size distribution is to be determined in a water tunnel. The ultimate resolution of the system including size determination by the digital picture processing system designed at the Drittes Physikalisches Institut is at present limited to 30 μm by the aberrations caused by the windows (thick PMMA) of the cavitation tunnel. The Nd:YAG laser proved to be a good alternative to a ruby laser. Bright phase holograms with high resolution could be made. The evaluation of the holograms shows as a result that the density of bubbles with a diameter greater than 30 μm was less than 0.1 per mm3 even in gassy water.
TL;DR: It is shown that old surplus ruby laser components found in most large research establishments can be reassembled into a configuration yielding high energy pulses of optical quality.
Abstract: It is shown that old surplus ruby laser components found in most large research establishments can be reassembled into a configuration yielding high energy pulses of optical quality. The highquality, low cost, and flexible design is well suited for many experimental and educational purposes.(AIP)
TL;DR: In this paper, the authors used photoluminescence measurements for identifying energy levels introduced by p-type impurities in the diffusion layers and derived an energy density threshold for diffusion of about 0.3 J/cm2.
TL;DR: In this paper, the Strouhal number was shown to change from 0.14 to 0.20 when the angle of approach of the wind altered by approximately 5° at certain angles.
01 Jan 1989-International Journal of Radiation Applications and Instrumentation. Part C. Radiation Physics and Chemistry
TL;DR: In this article, the authors showed that the optical conversion from metastable self-trapped excitons at the lowest triplet state (STE L ) to F centers in NaCl single crystals has been observed in the picosecond range with time-delayed double excitation spectroscopy.
TL;DR: In this article, the authors observed that the hydrogenated amorphous silicon (a-Si:H) films deposited by glow discharge method on Corning glass are transformed from the ammorphous to crystalline state by the ruby laser irradiation.